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Ministry of Mines The Islamic Republic of Afghanistan

THE STUDY

ON GROUNDWATER RESOURCES POTENTIAL

IN KABUL BASIN

IN THE ISLAMIC REPUBLIC OF AFGHANISTAN

SECTOR REPORT 6 CAPACITY DEVELOPMENT PROGRAM

March 2011

JAPAN INTERNATIONAL COOPERATION AGENCY (JICA)

SANYU CONSULTANTS INC.

GED

JR

11-077

SECTOR REPORT 6. CAPACITY DEVELOPMENT PROGRAM

Contents

CHAPTER 1. Introduction ...................................................................................................... 6-1

1.1. Background of the Study......................................................................................................6-1

1.2. Objective of the Study..........................................................................................................6-1

1.3. The Study Area.....................................................................................................................6-2

1.4. On the Sector Report 6 .........................................................................................................6-2

CHAPTER 2. Capacity Development Program .....................................................................6-3

2.1. Outline..................................................................................................................................6-3

2.2. Theme 1. Groundwater Development ................................................................................6-4

2.2.1. Groundwater General, Main Text ...............................................................................6-4

2.2.2. Groundwater Analysis, Main Text ...........................................................................6-24

2.3. Geophysical Prospecting ..................................................................................................6-52

2.3.1. Main Text 1. .............................................................................................................6-52

2.3.2. Geophysical Prospecting, Main Text 2 ....................................................................6-69

2.3.3. Geophysical Prospecting, Text 3. Operation Manual ...............................................6-79

2.4. Drilling Techniques ..........................................................................................................6-91

2.4.1. Drilling Technique General (Introduction to Well Drilling) ....................................6-91

2.4.2. Drilling Technique 2 (Casing Work & Full-hole Cementing) ..................................6-99

2.5. Well Logging and Pumping Test .................................................................................... 6-111

2.5.1. Well Logging, Main Text ....................................................................................... 6-111

2.5.2. Pumping Test, Main Text .......................................................................................6-122

2.5.3. Pumping Test, Analysis ..........................................................................................6-136

2.6. Cost Estimation and Tendering ......................................................................................6-155

2.6.1. Cost Estimation and Tendering, Main Text ............................................................6-155

2.7. Supervising and Project Evaluation ...............................................................................6-172

2.7.1. Supervising and Project Evaluation, Main Text .....................................................6-172

Photo Album

Photo Album 1. Scene of Capacity Development Seminar

Photo Album 2. Scene of Capacity Development Training

The Study on Groundwater Resources Potential in Kabul Basin in Afghanistan

Sector 6-1

Chapter 1. Introduction

1.1. Background of the Study

In the Islamic Republic of Afghanistan (hereinafter referred to as Afghanistan), its religious, political and military conflict has been settled and the efforts towards its restoration have just been initiated. The population of the Capital, Kabul City, had been by far below two million during the conflict, but recently it might have already reached three million as a result of repatriation of refugees after the cease-fire. There exists very old pipe-borne water supply covering almost entire part of the old city in Kabul and some local water supply systems by city-quarter constructed by late Soviet Union. As a result of lingered conflict, the rate of water supply coverage currently remains at about 20%. Many of the citizens who are not equipped with proper tap water facility utilize insanitary shallow groundwater through more than 3,500 (reportedly) of hand-pump wells, natural springs, or standing water of Kabul River. However, not only because of insanitary water qualities of those but steadily lowering groundwater level caused by random and haphazard development, the water supply system of Kabul City is facing to a severe calamity of water resources shortage. Now a day, it is already worried about the diminishing of groundwater resources in the Kabul Basin, unless any proper counter measures to save groundwater resources immediately.

Under such circumstance, the newly born Government of Afghanistan has requested to the Japanese Government a technical support through Development Study, based on the concept that it is indispensable to investigate the volume of existing groundwater resources and to explore newly available aquifers, taking the current water supply condition and increasing water demand of Kabul City into an account.

1.2. Objective of the Study

The objectives of the Study include the following three purposes:

1) to evaluate the potential of groundwater resources exploitable for drinking use in the Study area

2) to collect information necessary to formulate groundwater resources development program for the Study area

3) to transfer the techniques and methodologies of the Study on groundwater resources to the Counterparts of Ministry of Mines and relevant organization, during the course of Study.

The last objective was modified later, the target of technical transfer was enlarged to other governmental agencies concerned to groundwater development.


Sector 6-2

1) North Kabul Geohydrolic Area 2) Pole-Charkhy Geohydrolic Area 3) Darlaman－Chehilston Geohydrolic Area 4) Afshar Geohydrolic Area 5) Kabul Center Geohydrolic Area 6) Bagrami- Logar Geohydrolic Area 7) Neocene Plain Geohydrolic Area 8) Northeast Airport Geohydrolic Area 9) Logar River ~ Kabul River Geohydrolic Area

1.3. The Study Area

The Study area covers Kabul Basin in a narrow sense, in the center of which Kabul City is located. Further, the areas to survey deep groundwater resources were originally classified into nine (9) geo-hydraulic sub-zones as shown below.

However, the Study areas were re-classified into four (4) sub-basins by the Study Team through own review on the existing data and information. These were as follows:

1) North Kabul, 2) Pol-e-Charkhy, 3) Logar, and 4) Darlaman.

A location map is shown in the head of the report, where the four sub-basins are roughly delineated.

1.4. On the Sector Report 6

The Sector Report 6, “Capacity Development Program”, presents texts on all Capacity Development Programs conducted in the Study.

References include English main text, Dari version of the Text, Power Point presentations, and some photographs on the committee. Appendixes on these texts are not contained, because all of Appendix data and information are already attached in each Sector Report.


Sector 6-3

Chapter 2. Capacity Development Program

2.1. Outline

“Capacity Development Program on Groundwater Development” was added in the Study in the end of second Study Year (December, 2007), and actually started since the third Study Year (October, 2008).

Actual theme of the program were as follows:

a. Groundwater Development plan (2 terms):

a-1. Groundwater Development General; a-2. Groundwater Analysis and Evaluation;

b. Geophysical Prospecting (1 term): c. Drilling Work and Technique (3 terms):

c-1. Well Construction General; c-2.3. Casing Work & Well Completion;

d. Logging, and Pumping Test (2 terms):

d-1. Well Logging; d-2. Pumping Test

e. Cost Estimation, and Bidding (a half term): f. Supervising and Evaluation of Construction ( a half term):

Originally, the target agency to be involved in the transfer of technologies and capacity building program was only the DGEH. However, the targets were later expanded to include the following agencies.

- Department of Geo-Engineering and Hydrogeology: DGEH, Ministry of Mines,

- Afghanistan Geological Survey: AGS, Ministry of Mines,

- Central Authority of Water Supply and Sewerage: CAWSS, Ministry of Urban Development,

- Kabul Municipality, Ministry of Interior,

- Department of Irrigation and Water Resources: DIWR, Ministry of Energy and Water,

- Department of Rural Water Supply & Sanitation: Ministry of Rural Rehabilitation & Development.

In this Section, all of the Seminar Texts on Capacity Development Program, both English and Dari are presented one by one.


Sector 6-4

2.2. Theme 1. Groundwater Development

2.2.1. Groundwater General, Main Text

JICA Capacity Development Program, Lecture Text 2-1. Aspect: GROUNDWATER GENERAL

Contents 1. Fresh Water on the Earth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 Fresh water resources 1.2 Natural water circulation 1.3 Green Water and Blue Water

2. Water Resources Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1 Sustainable water resources development 2.2 Conventional water resources development 2.3 Non-conventional water resources development 2.4 Groundwater resources development 2.4.1. Groundwater occurrence 2.4.2. Groundwater resources development

3. Groundwater Investigation and Investigation Plan. . . . . . . . . . . . . . . . . . . . . . . . 11 3.1 Investigation for Groundwater Development

3.1.1 Investigation general 3.1.2 Data collection and review 3.1.3 Surface hydrogeological investigation 3.1.4 Subsurface hydrogeological investigation

3.2 Formulation of Groundwater Investigation Plan 3.2.1 Outlines 3.2.2 Area to Local investigation 3.2.3 Rough to Detail investigation 3.2.4 Monitoring 3.2.5 Reporting

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .16


Sector 6-5

1. Fresh Water on the Earth

1.1 Fresh water resources

Water, in particular fresh water, is one of the most precious and substantial properties of the earth. Sandra Postel said in her writing “Pillar of Sand1)”, “Water has two fundamental traits that distinguish it from any other resources. First, it is a prerequisite for life – no plant or animal, humans included, can survive without it. Second, there are no substitutes for water in most of its uses.”

Our Earth is called “Aqua-planet” or “Planet of Water”, and it means the earth has enough plenty of water. However, such quite plenty of water on the earth is sea water, and it can not be utilized by human beings and most of the living natures as it is.

The table 1.1.1 shows the water volume existing on the earth2). As shown in the table, the total water volume is around 1,386 million cubic kilometer (Mkm3), about 97% of it (1,351 Mkm3) is saline water like as sea water or salt lake water. Remaining is mostly fresh water, excepting very small amount of water existing as vapor or in livings. The amount of freshwater is roughly 35 Mkm3, around 2.48% of the total amount of water.

Such volume of fresh water among the total water volume is illustrated in a pie chart as shown in Figure 1.1.1. As easily understandable from the chart, the share of fresh water existing on land is quite small comparing with sea water. Further, the large part of the fresh water is ice or snow fixed in the North and South Polar Regions or at the top of high mountains such as the Himalaya Mountains, and those are also can not be utilized by plants, animals and human beings as they are. Thus, the amount of fresh water we can use it easily, such as groundwater, river water or water in lake and pond, is

Table 1.1.1 Water Volume on EarthCategory Volume Percentage

(103 km3) (%)Saline Water

Sea 1,349,929 97.5Salt-lake 94 0.007Subtotal 1,350,023 97.507

Fresh WaterIce 24,487.4 1.75Lake water 125 0.009River water 1.15 0.0001Soil retention 25 0.002Groundwater 10,100 0.72Subtotal 34,738.55 2.4811

Vaper 12.6 0.001Livings 1.2 0.0001Others - 0.0108

Total 1,384,775.35 100.0

Figure 1.1.1 Abandance Retio of Fresh Water

Water on Earth

97.5%

0.0%2.5%

Sea Water Vaper Fresh Water

Fresh Water

70.5%

29.1%

0.4%0.1%

0.0%

Snow/Ice Groundwater Lake, Pond

Soil-retain River


Sector 6-6

further small as only 10.25 Mkm3 (less than 30% of total fresh water volume), and it is equivalent to only 0.74% of the total water volume on the Earth.

1.2 Natural water circulation

Water is circulating in the natural condition, and because of this situation, water is fortunately renewable. The figure below3) shows the concept of natural water circulation on Earth.

As shown in the figure, the natural water circulation is started from a precipitation, rainfall or snow, falls on the land or the sea. A large part of the precipitation shall be evaporated or lost by transpiration through plant or vegetation. Remaining of the precipitation runs down the ground surface as rivers to pour into the sea and only some portion infiltrates into the ground to recharge groundwater. Groundwater shall also run down through underground and finally pour into the sea. In the sea, a huge volume of water is evaporating and some part of it is transferred to the land by wind. Vapor yielded by evaporation is, then, condensed into water in the sky to form clouds and again falls down on earth as rain or snow. Thus, the water circulation is closed.

Water in this natural circulation is renewable, or from other viewpoint, it can be developed in sustainable condition. The other water than naturally circulating, such as permanent ices in both poles or fossil water, are non-renewable, which must not be developed in general.

Previously, we discussed on the existing water volume on the earth, and now we discuss on the

Figure 1.2.1 Natural Water Circulation


Sector 6-7

circulating water volume, which is more important than the former because it is directly relating with the renewable water.

The following table (Table 1.2.1) shows the circulating water volume on the earth4) in each phase.

Water volume in vapor phase through evaporation and evapo-transpiration is around 577 x 103 km3, only 0.042% of the total water on Earth. Evaporation from sea is overwhelming.

A liquid phase of water is divided into three modes: precipitation, flow water, and soil retentions. Water volume in the mode of precipitation is same as the vapor, 577 x 103 km3. Then, the total water volume of surface and groundwater is about 45 x 103 km3, which is roughly 7.8% of precipitation. The water in this mode is called as “Blue Water” in line with water resources development. Among the modes, the volume of surface water is far larger than groundwater, more than 19 times.

Water volume retained in soil is another important, called as “Green Water”. The concepts of green water and blue water are to be described in the following section.

1.3 Green Water and Blue Water

The concept of “Green Water” and “Blue Water” is discussed in the “World Water Vision5)” reported in the 2nd World Water Forum (Hague, 2000). Followings are the extractions from the report:

Green Water: The rainfall that is stored in the soil and then evaporates or is incorporated in plants and organisms – is the main source of water for natural ecosystems and for rainfed agriculture, which produce 60% of the world’s food. Blue Water: Renewable surface water runoff and groundwater recharge – is the main source for human withdrawals and the traditional focus of water management.

World Water Vision said, the blue water available totals about 40,000 km3/year. Of this, an estimated 3,800 km3, roughly 10%, was withdrawn for human uses in 1995. Of the water withdrawn, about 2,100 km3 was consumed, and the remainder was returned to streams and aquifers, usually with significant reductions in quality.

It said also the volume of Green Water of around 60,000 km3. As shown in the table 1.2.1, the total

Table 1.2.1 Volume of Circulating WaterPhase Category Volume Percentage*

(103 km3) (%)Evaporation (inc. transpiration)

Land 74.2 0.0054Sea 502.8 0.0363

PrecipitationLand 119 0.0086Sea 458 0.0331

Runoff (Blue Water)Surface water 42.6 0.0031Groundwater 2.2 0.0002

Water in Soil (Green Water) 60 0.0043 *: % to the total water volume on Earth.


Sector 6-8

volume of “Green and Blue Water” is around 104,800 km3, and groundwater – the main theme of the Seminar – is only 2,200 km3.

1.4 Water shortage

In the beginning section, the volume of fresh water existing on the earth was discussed. That was only 10.25 Mkm3, only 0.74% of the total water volume on the Earth. The volume of 10.25 Mkm3 is sure a quite small amount in comparison to the total water volume on the earth; however, the volume is, practically, still rather huge volume for human. It is the volume which can cover the all land area6) on the earth with around 70m of water thickness as calculated below:

10.25 x 106 x 109 m3 / 147.2 x 106 x 106 m2 = 69.6 m

The world population as the end of 20 century was around 6 billion, and if simply allocated, the volume is around 1,750,000 m3/capita. The volume is too much enough for human consumption. Up to just recent, the water was assumed as infinite natural resources like as the air, in particular in the Asian countries.

But why water shortage nowadays?

It means, the human has at last noticed that the water on the Earth is not inexhaustible but the water which can be consumed is only within the volume that is renewable, and the fresh water resource is not only for mankind but for all living beings on the Earth.

As it was discussed so far, the total fresh water volume is, in quite simple calculation, still huge volume as 1,750,000 m3/capita, but the renewable water volume (Blue Water + Green Water) is about 104,800 km3/year in the world, which is converted to 17,470 m3/capita/year in an average. It became around less than 1/1,000 of the former. Even this, of course not all of the Blue Water is actually available, the amount seems to be enough for, at least, human kind.

If so, why the shortage of water is loudly argued recently?

For the question, I’d like to say there are two reasons. At first, because of the increasing population, enlarging production activities, and leveling up of living standard, the total fresh water demand for mankind is drastically increased. Secondly, the fresh water resources, represented with rainfalls, are quite unevenly distributed, or lost through an ill-management by the human.

The misdistribution of fresh water is classified into two categories: a specific misdistribution and a temporal misdistribution.

Specific misdistribution In the world, there are many and wide dry zones classified into “B” by Köppen’s Climatic Map,


Sector 6-9

which have less than 500 mm/year of precipitations, but there are also many countries in these zones. The specific water shortage is, thus, caused in the dry countries by the people who live in absolutely dry zone.

Temporal misdistribution In some of the countries, rainy seasons are in winter, from October to March. However, the most high water demand for irrigation use occurs from spring to autumn (in the Northern Hemisphere) and the irrigation demand is the largest fresh water requirement. Thus, the water shortage happens even though the yearly total fresh water resource is enough to cover all of those requirements. This is a temporal misdistribution.

There is another kind of water shortage caused by ill-management by human. Further in this category, there are two types: one is the major problem in developing countries and the other is major problem in developed countries.

Among the developing countries, some countries are suffered from chronic water shortage nevertheless they have rather enough yearly precipitation, only because they can not provide water supply facilities with economical, technical, or political poorness. The World Water Vision, explained above, showed the concept of “Economic Water Scarcity7)” and this is very near to the type I. The economic water scarcity means that countries have sufficient water resources to meet their needs but will have to increase water supplies through additional storage, conveyance, and regulation systems by 25% or more to meet their needs in 2025. These countries face to severe financial and capacity problems in meeting their water needs.

In the developed countries, they developed both surface and groundwater resources disorderly through their quite rapid economical and technical growth in the late 20th century. In the course of ill-managed water resources development, many rivers or aquifers were damaged or destroyed by over withdrawal and artificial contamination. Some of the groundwater systems were too much deteriorated to utilize any more, and reduced the water resources potential artificially.


Sector 6-10

Table 1.4.1 Relationship between abuse of water and environment

Industry

Agriculture

Living

Over Withdrawal

Hazardous Waste

Domestic Waste

Lake, Pond

River

Soil

Groundwater

Sea

Marine contamination

Lake contamination

River contamination

G.Water contamination

Soil contamination

Lake dim inishing

River losing

G.water level down

Aspect Means Objects Results

Table 1.4.1 shown above indicates the relation between abuse of water and Environmental issues. Major aspects causing abuse of water are industry, Agriculture, and living. Major means to abuse are over withdrawal, hazardous waste, and domestic wastes. Objects of the abuse are Sea, Lake/pond, River, Groundwater, and Soil, and then there are many results of those actions.

Finally, we must discuss with an international conflict and armed clash, such as Palestinian issue, Afghanistan, and Iraqi issues. Such social or political problems, especially violence deteriorate the water resources and keep the people away from the access to appropriate water source. They shall cause another type of water scarcity.

1.5 Measuring Water Shortage

Up to the previous section the water shortage was discussed through its definitions and qualitative aspects. Now it is to be shift to its quantitative aspects.

There are several methods or indexes to measure the water shortage (see Table 1.5.1).

The most popular and prevailing measurement is the “Falkenmark Indicator”.

This is presented by Malin Falkenmark8) as an index to show the water stress. The indicator is renewable water resources per capita per year, often on a national scale. She said, water stress begins with when there is less than

Tablle 1.5.1 Measurement of Water Shortage

・ The Falkenmark Indicator・ The Critical Ratio of Withdrawal・ The Current Basin Use Factor・ The Potential Basin Use Factor・ Water Poverty Indez (WID)・ Others


Sector 6-11

1,700 m3/capita/year for all major functions (domestic, industrial, agricultural, and natural ecosystems) and becomes severe when there is less than 1,000 m3/capita/year. When there is only less than 500 m3/capita/year of water, it is called as absolute water scarcity. But the Falkenmark indicator does not account for the temporal variability in water availability or for actual use. Its advantage is that the data are widely available.

The capacity ratio of withdrawals for human use to renewable resources is an indicator that does account for actual use. This ratio is used for the United Nations Comprehensive Freshwater Assessment. Nor does the ratio take into account available water infrastructure and water management capacity. For example, the ratio shows Belgium and the Netherlands as having very high water stress (actually they have not high water stress).

A more precise (but much harder to estimate) indicator is the current basin use factor. It relates total consumptive use to the primary water supply. When this factor is low – say, 30% – water could be saved and put to more consumptive use. When this factor is around 70% it is difficult and often undesirable to consume more water.

Potential basin use factor relates total consumptive use to the usable water supply. The distinction between the renewable resources in a basin and the primary water supply allows distinctions between physical and economic water scarcity.

Water Poverty Index (WPI) is a new holistic water management tool developed by Keele University and adopted by UK. The index is based on a holistic framework. During the participatory development process, five key components: resources, access, capacity, use, and environment, are indicated in order to capture the wide range of issues which are relevant. This needs some complicated procedure but it can assess the water poverty condition of the country exactly, and quite suitable to monitor the process of development of water resources.

Table 1.5.2 shows the worst ten countries in water scarcity, measured by the three methods of Falkenmark, Critical Ratio, and WPI9).

Because of the difference of calculation, the sets of worst countries are a little different, but most of them are located in Africa and Middle East.


Sector 6-12

In comparison through the Falkenmark Index, the worst country in the world is Seychelles with the index of nothing, followed by Kuwait and Palestine. On the contrary, the most rich country is Iceland (599,944 m3/capita/year) followed by Guyana in the South America (314,963 m3/capita/year) and Congo in Africa (259,547 m3/capita/year).

In comparison through the Critical Ratio, the worst country is Kuwait of more than 3,000%, followed by UAE (1,600%) and Saudi Arabia (95%). The rich countries are Bhutan, Cambodia, Myanmar, and Laos in Asia, Iceland in Europe, Angola, Cameroon, Central Africa, Congo, Guinea, Guinea-Bissau, Liberia, Mozambique, and Sierra Leone in Africa, Bolivia, Colombia, Paraguay, and Suriname in South America. These countries have the C.R of almost 0.

Then in comparing with the WPI, the most water rich country is Finland of 79.9 point followed by Suriname of 78.6 and Iceland of 74.4 point.

Table 1.5.1. Countries in Water ShortageWorst Falkenmark Index Critical Ratio WPIorder Country (m

3/y/c) Country (%) Country (-)

1 Seychelles - Kuwait 3,098 Haiti 32.72 Quiet 10 U.A.E 1,614 Ethiopia 34.03 Palestine 52 Saudi Arabia 955 Burkina Fasso 35.94 U.A.E 58 Libya 801 Niger 36.05 Bahamas 66 Oman 181 Eritrea 36.96 Qatar 94 Jordan 151 Burundi 37.47 Maldives 103 Uzbekistán 132 Chad 37.88 Libya 113 Egypt 127 Malawi 38.09 Saudi Arabia 118 Yemen 123 Benin 38.8

10 Malta 129 Turkmenistán 116 Serra leone 40.9


Sector 6-13

2. Water Resources Development

2.1 Sustainable water resources development

Reflecting the disordered water resources development in late 20 century, the concept of “sustainable development” is emphasized nowadays. For the sustainable development of water resources, it is required to make a development plan to withdraw water less than the renewable amount based on the natural water circulation on the target area.

Figure 2.1.1 shows the modeled natural water circulation10), which is the same with basic concept of “Synthetic Storage Model (SSM)”, one of the main themes in this lecture.

Non-groundwater Basin Groundwater Sub-Basin 1 Groundwater Sub-Basin 2

RF ET Groundwater Sub-Basin 3

S. Dam RF ET Sea h SF R. Intake RF ET

h SF　　　　A(1,2) R.Dam RF ET

SI h SF　　　　　A(1,2)

SR SI 　　　　　A(1,2)

SR

ET 　　　A(1,1) SR SF

PC SF　　　 A(2,2) ET 　　　　A(1,1) SR OF

SI PC SF　　A(2,2) ET 　　　　A(1,1)

SI PC SF ET

SI PC

SR

　　　A(2,1) SR SF

　　　A(2,1) SR OF

　　　A(2,1)

Common W.Resources RE

Development Scheme G.W. Withdrawal RE A.Recharging AR

a. Storage Dam DF1 DF1 RE U. Dam

b. River Intake H1 H1 　Spring

c. Spring Intake H1 　　　　　SP

d. G.W. Withdrawal SY1 　　　　　GA1 SY1 　　　　　GA1 　　　　GA1 　Ground Surface M.Spr.

Sea Intake

Aggressive W.Resources GR1 GI1 GR1 GI1 GR1

Development Scheme 　　L(1/2) H2 　　L(1/2) H2 　　　L(1/2) Sea-bottom Spring

a. Recharge Dam DF2 DF2 DF2 H2 　　　　　　SPS

b. Artificial Recharging

c. Underground Dam LR1 LR1 LR1

d. Marine-spring Intake

　　　　　GA2 　　　　　GA2 GA2

GR2 GI2 GR2 GI2 GR2

H3 　L(2/3) H3 　L(2/3)　　L(2/3) 　　DF3 H3

LR2 LR2 LR2

　　　GA3

　　　　　GA3

GR3 GI3 GR3 GI3 GR3

Figure 2.1.1 Hydrological Circulation Model & Concept of Water Resources Development

Surface System

SY3

SY3

SY3

SY2

SY2

Unconfined Aquifer

Confined Aquifers

SY2

Almost all of the water resources development schemes can be explained in this model.

In the past, surface water was taken from a river directory or through a dam after once stored. Groundwater was taken directory through Qanat (or Kalese in the region) or withdrawn through wells with manpower or pump. All of these intake methods are quite simple, taking water as it was.

Recently, some other kinds of approach to develop water resources are raising gradually, called as “Aggressive Development”. These schemes intend to take water not in natural condition but quite positively, treating its existing mode sometimes.


Sector 6-14

2.2 Conventional water resources development

Conventional water resources development schemes are common development schemes applied for long time. This scheme includes a storage dam, a direct river intake, and a direct spring intake, a simple groundwater withdrawal through wells or other systems, and so forth as indicated in the figure.

Then, so-called “Aggressive Development” includes a recharge dam, an artificial recharging, an underground dam, a development of marine spring, etc. These were rather recently developed but substantially included in the conventional water resources development scheme in the meaning to develop the natural water resources, although they were heavily extended from their original development methods.

Recharge dam is constructed to infiltrate surface water into the ground forcibly, having no purpose to storage water. This is quite efficient when it is combined with underground dam at its downstream.

Artificial recharging is to increase groundwater recharge forcibly. The recharge dam, mentioned above, is also one of this scheme. A detour channel recharging is included in this category. Besides them, an artificial recharging through wells is another main category in this scheme. This is to inject excess water in rainy season or flooding into a certain aquifer which has enough storage capacity through recharging well, and to withdraw the injected water later when it is needed.

Underground dam scheme is to store groundwater in certain aquifer by constructing a cutoff wall in the course of groundwater flow. In Japan, there were several underground dams recently constructed by MOAFF or ex MOC. Underground Dam scheme shall be discussed in the other occasion.

2.3 Non-conventional water resources development

All of these development schemes explained so far are just natural surface water or groundwater resources development schemes. But in some regions, these traditional water resources development schemes are already or just approaching to the limit of application. Thus, new types of water resources development schemes are seriously considered recently, called as “non-conventional water resources development”.

A representative of this scheme should be “Desalination”. It’s almost becoming in a ripening

Table 2.3.1. Classicication of Desalination System

・Multi Stage Flash (MSF)

・Multi Effact (TVC-ME)

・Mechanical Vapor Compression

(MVC)

・Reverse Osmosis (RO)

・Electric Dialysis (ED)

ThermalProcess

MembraneProcess

DesalinationSystem


Sector 6-15

period technically, and so many desalination plants are in-service widely in the world. Table 2.3.1 shows the classification of desalination systems. Nowadays, the Reverse Osmosis system (RO) in membrane process is coming up to the mast prevailing desalination system.

Another major non-traditional water resources development scheme is “Water Reuse Loop”, and main two items in this category is sewerage water reuse loop and reuse loop of industrial waste water. The latter, reuse of industrial waste water is already prevailing in the developed countries, but the former is on going in most of the countries in the world.

Finally, there is unique water resources development scheme; to import fresh water itself. In the past, water was traded widely in the mode of virtual water, mostly as a food such as meet or vegetable, but recently, water is going to be traded directly as water. Right now, two types of water transporting means are considered, one is a pipeline as same as an oil pipeline and another is shipping (See the picture11)).

2.4 Groundwater Resources Development

2.4.1 Groundwater occurrence

Figure 2.4.1 is a schematic cross section of the upper portion of the earth’s crust for explanation of the groundwater occurrence12). Near the surface in the zone of unsaturated (aeration) pore spaces contain both air and water. Water in the zone is known as suspended or soil retention water. The thickness of the unsaturated zone varies from practically zero in swampland to some hundred meters in arid regions with substantial relief.


Sector 6-16

Occasionally local zones of saturation exist as perched groundwater above a locally impervious stratum. Sometimes a body of groundwater is overlain by an impervious stratum (confining layer) to form confined or artesian water. Confined groundwater is usually under pressure because of the weight of the overlying soil and hydrostatic head (indicated as piezometric head in the figure). If a well penetrates the confined aquifer, water will rise to the piezometric level, the artesian equivalent of the water table. If the piezometric surface is above ground level, the well discharges as a flowing well. To understand the groundwater occurrence and the existing condition is very important to make up any groundwater resources development scheme.

2.4.2 Groundwater resources development plan

The groundwater resources are, excepting fossil water, renewable resources in the natural water circulation fortunately. Fossil water is groundwater which is trapped in the strata in old geological time and separated from the current natural water circulation, or has been recharged continuously for long time at the remote recharging site but quite small amount. Continental Intercarail, extended widely in the North Africa, is one of the typical fossil water. That is quite excellent aquifer but not renewable so that it should be vacant at any day if it is continuously withdrawn.

Sustainable water resources development is to develop water in the natural water circulation and within the amount of renewable. In the case of groundwater resources development, the renewable amount is equivalent to the volume of recharge from the surface system. In this meaning, it is quite important to evaluate the volume of groundwater recharge.

Practically, groundwater resources development schemes are classified as shown in Table 2.4.1.


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And the positions of them sharing in the natural water circulation should be recognized through the Figure 2.1.1.

Table 2.4.1 Groundwater Development SchemesCategory Method Site Withdrawal Type Development Scheme

(Direction)Direct use

In-situ In-land Artesian Spring UtilityOffshore Artesian Submarine Spring

Withdraw (Hirozintally) Gravity Qanat (Kalase, Falaj, etc.)(Vertically) Manual Dug Well

Manual pump Well with handpumpEngine pump Single Well with engine pump

Group Well FieldWithdraw (Hor./Vertical) Engine pump Collection Well

Collection ConduitIndirectuse

Storage In-land Intake facility Underground Dam inlandShore side Intake facility Underground Dam shoreside

Increasingrecharge

(combination use with abovedevelopment schemes)

Naturalseepage

River side Intake facility Detour Seepage

Tentativestorage

River route Intake facility Retention Dam

Injection In-land Intake facility Artificial Recharging

The most simple groundwater use is a direct use of spring, because a spring is an outcrop of groundwater. Mankind must have begun to utilize groundwater by direct spring use, and then they contrived to use groundwater by “Hand Dug Well” or “Qanat” in where there is no spring. A quite primitive concept of “Underground Dam” is also said to be date back to the Roman Age.

Groundwater development schemes included in the direct use are rather traditional methods to utilize groundwater. The items classified in the indirect use are modern underground dam schemes, different from the one mentioned above. Together with the items in “Increasing recharge”, these are recently developed in accordance with the progresses of construction technique and, in particular, with the computer simulation technique.

To formulate a groundwater development plan, the purpose of the plan must be defined clearly together with the target area and a project period at first, then, the suitable development scheme as shown in Table 2.4.1. shall be identified under the consideration of hydrogeological condition of the area obtained through a preliminary data collection and review on them. Based on the purpose of the plan and development scheme, actual hydrogeological investigation plan shall be formulated and conducted. Groundwater development plan shall be formulated finally based on the results and evaluation of the hydrogeological investigation. Depending upon the results of such investigation, the development scheme may be changed or modified.

Hydrogeological investigation methods and formulation of the investigation plan shall be explained in the following chapter.


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3. Groundwater Investigation and Investigation Plan

3.1 Investigation for Groundwater Development

3.1.1. Investigation general

There are many geological investigation schemes and method, and among them, investigation schemes concerning to a groundwater development scheme are called as “hydrogeological investigation.”

Hydrogeological investigation schemes are, almost same with common geological investigations, classified roughly into two categories: Surface investigations and Subsurface investigations. Surface investigations include geologic methods, remote sensing, and geophysical exploration. Subsurface investigations include a test well drilling, and several in-situ tests conducted in the wells.

Besides those actual investigation schemes, data collection and review on them, performed prior to the actual investigation or in the course of investigation, is another important scheme for both formulating an investigation plan and groundwater development plan.

3.1.2. Data collection and review

Data to be collected and reviewed are also classified into two categories of a. Direct hydrogeological data and b. Meteor-hydraulic data. The former are required to formulate a groundwater development plan or an investigation plan, and the latter are needed to groundwater balance study or evaluate a groundwater resources potential through a simulation study. Items and kinds of data to be collected and reviewed are shown bellow:

a. Direct hydrogeological data 1. Maps; - topo-maps in several scales, -geological map, hydrogeological map, - landuse map, -vegetation map, geographical map, etc. 2. Aerial photos; - aerial photos in some scales, -satellite images, etc. 3. Study reports; - geological investigation, -hydrogeological study, -groundwater study, - environmental study, -meteoro-hydraulic study, etc. 4. Geological references; - published geological books.

b. Meteor-hydraulic data 1. Meteorological data; - daily rainfall, -daily snowfall, -daily temperature (max. min. ave.),


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- evapo-transpiration (or evaporation) 2. Groundwater data; - groundwater level in the target area, -groundwater temperature, - groundwater quality, -well inventory, -spring inventory, - groundwater withdrawal, etc. 3. Hydraulic data;

- river water runoff records at required station.

3.1.3. Surface hydrogeological investigation

As explained above, surface hydrogeological investigations include a. geologic methods, remote sensing, and geophysical explorations. Each scheme includes several investigation methods as shown bellow;

a. Geologic methods; 1. Field geological reconnaissance survey, -geological mapping, -geo-morphological mapping,

b. Remote sensing; 1. Aerial photo interpretation -geo-morphology, -lineaments, -structure lines, -vegetation cover, -drainage system, -springs, -marsh/ponds/lakes, -artificial water features, etc. 2. Satellite image analysis -pseudo-color image, -surface moisture analysis, -vegetation cover, -lineaments, etc.

c. Geophysical exploration; -Geo-electric sounding, -electro-magnetic prospecting, -seismic exploration, -gravity exploration, -magnetic exploration, -ground temperature exploration, etc.

3.1.4. Subsurface hydrogeological investigation;

a. Drilling and In-situ tests; 1. Investigation boring: -all core boring, -non core boring, -tests in borehole (logging, permeability test, yield test, etc), -groundwater tracing. 2. Test well and observation well(s) -tube well, -dug well, -radial well, -collecting conduit, -observation well, etc. 3. Test well field -well field, -group pumping test.


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b. Tests in well; 1. Well logging; -electric logging, -spontaneous potential logging, -gamma ray logging, -temperature logging, -caliper logging, -acoustic logging, borehole camera, etc. 2. Pumping test; -preliminary test, -step drawdown test, -continuous discharge test, -recovery test, etc. 3. Water quality analysis; -chemical analysis, -micro biological analysis, -physical analysis, -isotopic analysis, -in-situ water quality tests, etc. 4. Water level measurement; -periodical water level measurement, -simultaneous water level measurement, -continuous water level measurement, -spring yield measurement, etc.

3.2 Formulation of Groundwater Investigation Plan

3.2.1. Outlines

Groundwater investigation plan should be formulated to obtain good enough information to build up a groundwater development plan. The information required to build up a groundwater development plan are quite varying depending upon the development schemes, and therefore, those are very important that what’s are required to formulate a certain groundwater development scheme, and what’s are obtained from any investigation schemes or methods.

Almost all of hydrogeological investigation scheme and/or methods are listed up in the previous section. The method itself, how to conduct and how to report, and what’s are obtained from, are to be studied by yourself. In this section, only some basic policies on formulating investigation plan, such as “area to local”, “rough to detail”, and so on, are explained. Further, two big items of “well logging,” and “pumping test,” shall be discussed more through individual seminars and field trainings.

3.2.2. Area to Local investigation

The most basic policy on formulating investigation plan is to investigate rather wide area surrounding the target site at first, and then, to investigate the target site or point. Hydrogeological condition of a certain area, site, or point, is widely extending to surrounding area, or outer site but gradually changing in most of the cases. However, it’s suddenly changing based upon geological discontinuity sometimes. In both cases, a wide area investigation can show an exact situation of the target area or the site among a natural circumstance.


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Local investigation only for the target area or site is economical, but it can not indicate the situation of the target site among wide hydrogeological tendency, and may fail to catch an abrupt hydrogeological change near the site sometimes. Only for a very small scale groundwater development plan, such as a sole well drilling, a local investigation may be allowed. Scale of the wider area is also depending upon the scheme of development plan and original area of development, but it shall be around double of the original area, in most of the cases.

3.2.3. Rough to Detail Investigation

The second policy for investigation planning is to make investigation roughly at first, and then, make more and more in detail step by step. Of course, this policy shall be combined with the first policy mentioned above. Wide and rough investigation to local detail investigation is the most basic policy on almost all investigation or research projects.

Rough investigation means, usually, to make rough its investigation density. For example, to set one VES point in 4 km2 in a rough investigation step and set it in 1 km2 or 0.25 km2 in a detail investigation step. Besides this, there are some investigation schemes suitable for a rough investigation, e.g. a data collection and review, a remote sensing, a field hydrogeological reconnaissance survey, and a geophysical prospecting. While, typical hydrogeological investigation schemes for a detail investigation are investigation boring, test well/observation well drilling, and in-situ tests in these boring or wells.

Usually, the cost of detail investigation is higher than the rough investigation, and therefore, it is important to make a balance on rough and detail investigation. In the case of this JICA study, the first year was spent for a rough investigation, and both the second and third years shall be appropriated to a detail investigation.

3.2.4. Monitoring

Hydrogeological monitoring is another important scheme for both hydrogeological investigation and groundwater development plans. There are two kinds of hydrogeological monitoring; a groundwater monitoring during the investigation period and a monitoring after the completion of groundwater development project. The former is to obtain hydrogeological information to grasp the groundwater condition of the target area and to serve for groundwater simulation study. And the later is for checking groundwater behavior, such as groundwater level, quality, well yield, etc., for a certain period after completion of the groundwater development project. This is very important to evaluate the project, whether it is going well along its purpose and there is any adverse reaction or not.

3.2.5. Reporting

Results of the hydrogeological investigation must be analyzed, evaluated, summarized, and


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reported properly. In the case of common investigation work for small scale groundwater development project, individual report on each investigation or combination report of some investigation results shall be prepared. In the case of large investigation work such as JICA development study, several reports are to be prepared and submitted occasionally;

a. Inception report: at the beginning of the study, b. Progress report 1: at the period progressed a quarter, c. Interim report: at the period progressed a half, d. Progress report 2: at the period progressed three quarters, e. Draft final report: after completion of the study, f. Final report: after explanation and discussion with a client.


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References 1) Sandra Postel (1999) “PILLAR OF SAND”, W.W.NORTON & COMPANY

2) Kayane Isamu (1980) “Mizuno Junkan”, Kyoritu-shuppan

3) Translated from Ohnishi Ikuzou (1990) “Chikasui no kagaku I”, Doboku-kougaku-sha, pp7

4) Morisawa Sinsuke (2003) “Chikyuu Mizusigenn no Kanri-gijutu”, Korona-sha, pp9

5) Kawa to Mizu IInkai (2001) “WORLD WATER VISION”, Sankai-dou, pp78

6) F. Machatsuchek (1975) “Geomorphology”, Gihou-dou-shuppan, pp1

7) W.J. Cosgrove & F.R. Rijsberman (2001) “WORLD WATER VISION”, EARTHSCAN

8) Population Action International Sustaining Water “Population and Water Stress” ： http://www.cnie.org/pop/pai/water-12.html

9) F.I: UNESCO PRESS (2003), C.R: World Resources, 2002-04, WPI: Keele Economic Research, 2002

10) Ryoichi Kawasaki “APPLICATION OF SYNTHETIC TANK MODEL SIMULATION ON THE AREA WITH POOR BASIC HYDROLOGICAL DATA AVAILABILITY” Simanto Ryuiki Gakkai No.2, Vol2 (2003), pp17

11) Nippon Yusen (2000) “News Release”: http://www.nykline.co.jp/2000/20000524/20000524.htm

12) Modified & Translated from Kaisuikyou (2001) “Presentation for MOFA”


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2.2.2. Groundwater Analysis, Main Text

JICA Capacity Development Program, Lecture Text 2-2. Aspect: EVALUATION OF GROUNDWATER POTENTIAL

SYNTHETIC STORAGE MODEL 1. INTRODUCTION OF SYNTHETIC STORAGE MODEL (SSM) . . . . . . . 1

2. SUGAWARA’S TANK MODEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3. SYNTHETIC STORAGE MODEL (SSM) . . . . . . . . . . . . . . . . . . . . . . . . . . 2

4. SSM & UNDERGROUND DAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

5. CONCEPT OF SSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

6．CHARACTERISTICS OF SSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

7． PROCEDURES OF SSM SIMULATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

8． DATA PREPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

9． MODEL CONSTRUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

10． VERIFICATION OF THE MODEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

11． WATER BALANCE SIMULATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

12. FUNCTIONS OF SSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

13. CONBINATION USE WITH OTHER SIMULATION MODEL . . . . . . 24

14. SSM PROGRAMME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26


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SYNTHETIC STORAGE MODEL

1． INTRODUCTION OF SYNTHETIC STORAGE MODEL (SSM) Quite simply saying, the Synthetic Storage Model (SSM) is an extended application of the Tank Model to subsurface system. I have been developing the integrated water flow/balance simulation model to combine surface and groundwater system using SSM, and could have the conviction that the model is particularly effective to analyze a comprehensive water balance in the area where not enough basic hydrological data available.

2． SUGAWARA’S TANK MODEL The Tank Model is one of the world famous simulation models of surface water runoff analysis,

developed by Dr. M. Sugawara (National Technical Center of Disaster Prevention, 1972) [1].

As it is well known, the model is a serial storage type runoff system.

The surface runoff system is explained by plural tanks connected vertically. Those tanks usually consist of three levels. Every tank has some orifices on its side and bottom. The side-flow from the upper tank indicates flood or a high surface flow; the one from the middle tank means a normal river flow; and it from the lowest tank is a base flow. The water infiltrating from the lowest tank recharges the groundwater [2].

Since the model was published, it was adopted by many official agencies in charge of water resources development or

management in and out of Japan, owing to a

simple and easily understandable model, and nevertheless, it indicates very accurate response for surface runoff. By the same reasons, several applications for runoff analysis or water balance simulation were developed. The Synthetic Storage Model (SSM) introduced herein is one of the applications of it, extended to the groundwater system.


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3． SYNTHETIC STORAGE MODEL (SSM) The SSM was developed by M. Yoshikawa (1976, [3]) and established through the course of

development of Underground Dam Scheme, under the closed cooperation with the Ministry of

Agriculture, Forestry and Fishery (MOAFF), Japan [4]. After the completion of the “Minafuku Experimental Underground Dam” in Okinawa, it was established and applied by the Ministry formally as one of the effective water balance simulation models. Then, the model was applied for several projects in the world under Japan’s ODA, e.g. in Nepal [5], Lebanon [6], Syria [7], and etc.

4． SSM & UNDERGROUND DAM

The model is, as mentioned above, originally the extension of “Tank Model Simulation” to the groundwater system. “Tank Model” explains the surface system with one or plural tanks with some orifices on the bottom and side. SSM is simply the extension of the tanks to groundwater system as shown in the figure.

In the Figure 2, RF means Rainfall, SI is Surface Inflow, and SF is Surface outflow (Runoff). ET means Evapotranspiration, SR is Soil Retention. PC, RE, and DF are Percolation, Recharge, and Drafting, respectively, and SY is Specific Yield.

As I explained above, the SSM has been developed in close relation with an underground dam scheme cooperated with MOAFF of Japan. The figures show the Miyako Island and Minafuku Experimental Underground Dam constructed by MOAFF in 1979.

SI

RF

ET

A(1

,3)

SF

SF

SR A(1

,2)

A(1,1) Surface

PC Syatem

ET

SF

SR A(2

,2)

A(2,1)

RE

DF1LEGEND

SY1

RF: Rainfall H1 UnconfinedET: Evapotranspilation Groundwater

SI: Surface Inflow GA

1 System

SF: Surface Runoff GI1 GR1

SR: Soil Retention L(1/2)

PC: Percolation B(1/2) H2DF2

RE: Recharge

LR2

GI: G.W. Inflow

SY2

GR: G.W. Runoff

DF: G.W. Draft GA

2

LR: Leaky Recharge GI2 GR2 Confined

H: G.W. Head L(2/3) Groundwater

SY: Specific Yield B(2/3) H3 SystemDF3

A: Runoff CoefficientLR3

GA: ditto for G.W.

SY3

L: Leakance

B: Aquiclude Thickness GA

3

GI3 GR3


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5． CONCEPT OF SSM Basic concept of SSM is the quite faithful embodiment of natural water circulation on the Earth.

The figure is a simple natural water circulation model. As shown in the Figure, the natural water circulation is started from a precipitation, rainfall or snow fall. A large part of the precipitation shall be evaporated or lost by transpiration through plant or vegetation. Remaining of the precipitation runs down the ground surface as rivers to pour into sea

and only some portion infiltrates into the ground to recharge groundwater. Groundwater shall also run down through underground and finally pour into sea. In the sea, a huge volume of water is evaporating.


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The SSM is shown above. As shown in the figure, the model embodies the natural water circulation honestly. The model equips every unit basin with functions of a precipitation (RF in the figure), an evapo-transpiration (ET), a surface runoff (SF), an infiltration (PC) or recharging (RE) and a groundwater flow (GR).

In the model, the water circulation is started from a precipitation (RF). Some part of the precipitation is lost through an evapo-transpiration returning back to the air (ET), some portion is captured in the soil as a retention water (SR), some portion is percolated into the deeper unsaturated zone (PC), and the remain flows out to the downstream zone (SF). In the next (Downstream) zones also, they have a precipitation, losses by ET, SR, PC, and a gain of inflow from

upstream zone. Those upper tank series in the figure are called as “Surface System”. The second row of tanks within the surface system is called as “Delay System” but practically it means unsaturated zone. In some particular regions, the second tanks are lacking because of the situation of foundation geology.

Normally through the second tanks, or directly from the uppermost tanks, some portion of the

precipitation infiltrates into saturated zone, as a recharging of groundwater (RE). The groundwater system is divided into two categories: unconfined aquifer system of the uppermost raw, and confined aquifer system of the lower rows.

Groundwater table (H1) of the unconfined aquifer is simply decided by the gains of groundwater in a certain sub-basins such as groundwater inflow minus outflow (GR1), recharge amount (RE), and its storage coefficient (SY1). Further, some part of groundwater is leaking into confined aquifer system (LR).

Confined aquifer has no groundwater table but has a piezometric head (H2) decided by the balances of inflow and outflow (GR2), and leakance (LR) under the condition of storage coefficient (SY2).

In both of surface and groundwater systems, the precipitation water pours into the sea finally. In the case of groundwater, when the water table intersects the ground surface, groundwater comes out to

the ground as a spring (SP). Under the sea also, if the aquifer has enough high water head than the depth of the sea, it springs out to the bottom of the sea, forming a submarine spring (SPS).

6． CHARACTERISTICS OF SSM

(a) Characteristics of SSM Simulation The Model (SSM) makes a quite simple calculation as; in every sub-basin at daily basis,

“(RF) – (ET) – (SR) － (SF) = (RE)”.

Groundwater system starts through the Recharge from the surface tanks. In the groundwater tank, the recharge amount is converted into the increasing of the groundwater level in

accordance with a Strativity (or Specific Yield: SY) of the ground, such as: “(RE) / (SY)” =


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increasing groundwater level (H)”. Groundwater flow is to be decided by the comparison of groundwater levels (H1) in between neighboring sub-basins, and

groundwater runs from high to low level sub-basin, in accordance with “Darcy’s Low”.

Generally, in the hydraulic analysis which applies the potential solution methods such as FEM and FDM (for example “MODFLOW”), the water head is initially solved, and

then the water storage is secondarily defined. On the contrary, SSM solves initially the

change of storage (balance) of an aquifer in a sub-basin through the recharge from Tank Model, and water head is driven through the relationship between the storage and head which has been previously defined. This methodology is the big particularity of the model, and is the origin of the model’s name10).

Because of the characteristics, the model can analyze both surface and groundwater balance simultaneously under the condition of minimum available data sets. It needs only rainfall data and some runoff observation data at least enough to make (Surface) Tank Model Simulation, then, it can estimate roughly the groundwater system and balance.

(b) Merits and Demerits

SSM has several merits as listed below, and these are quite useful or convenient to analyze the comprehensive water balance in the developing countries, those lack or have too short hydrogeological data or records.

a. The model embodies honestly a natural water circulation, so it is easily understandable.

b. The model can analyze water balance, both surface and groundwater, under the condition of minimum available data sets.

c. The model deals with the target area into sub-basins arbitrarily, so that it can divide the area into preferable sub-basins.

d. The model has a function which can express the spring phenomena.

e. The model has a function that can express a tunnel or canal that conveys water from a certain basin to another basin.

f. It has strong pumping simulation function, so it can make any stories of future pumping simulation13).

g. The model has the function of “underground dam” simulation, because it has been developed for.

h. The major outputs of the simulation are rainfall, evapo-transpiration, runoff, spring


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out, etc., in each sub-basin, at daily basis.

i. It calculates groundwater level and groundwater flow of each sub-basin at daily basis.

j. The SSM Program is written using Visual Basic (Microsoft); therefore, it is very easy to understand the program.

Those are some of the merits of SSM simulation, and the reason why the model was adopted in most of hydrogeological studies. On the other hand, SSM and its simulation have also demerits. These are mainly for methodology on operation and structures, such as:

a. The target area of the Study shall be divided into desired shaped sub-basins and the calculation and verification shall be conducted on sub-basin basis, therefore, the number of sub-basins has practically a limitation.

b. Verification of the surface system is a pattern matching between actual runoff records and model outputs through tank model simulation. Pattern matching is a kind of trial and error approach, and it needs some patient works and sense to obtain smooth and good results. Some users do not like these procedures.

c. Verification of the groundwater system is called “Direct Verification” and it is also a pattern matching between the model outputs and actually observed groundwater hydrograph. And, this procedure has the same problem mentioned above.

7． PROCEDURES OF SSM SIMULATION To carry out the SSM simulation, the procedures are divided into major four steps: 1) Preparation of the data sets, 2) Construction of the model, 3) Verification (or Calibration) of the model, and 4) Water balance simulation, as summarized in the Figure.


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8． DATA PREPARATION Three sets of data are required for the SSM Study; 1) data set for model construction, 2) data set for input data, and 3) data set required for the model verification.

(a) Data for Model Construction Data set for model construction include a) topographical information such as 1/50,000 topo-map, 1/200,000 geographical map or satellite imagery, b) geological and hydrogeological information such as geological map, hydrogeological map, and geological cross sections, c) meteor-hydrological information such as isohyets map or location maps of meteorological stations or river floe gauging stations, and d) aquifer information such as aquifer structure, aquifer constants, or groundwater quality.

(b) Data for Input As the basic input data, the model requires daily precipitation records. In the case of cold region, the snow fall records (both daily snowfall and snow depth) are also required for exact water balance simulation.

SSM Model required evapo-transpiration data also, but in monthly basis. When the data set on evapo-transpiration is not available, data set of pan evaporation shall be adopted as a supposition of evapo-transpiration multiplied by 1.1 (or increasing 10 % of it).


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(c) Data for Verification To verify the constructed model, two kinds of data sets are required: Runoff data to verify the surface system and Groundwater hydrograph to verify the groundwater system.

For the verification of surface system, it is no need to prepare runoff data for all river basins but for only typical or major river basins. Other river basins can be applied the same structure. In the case of subsurface system, data sets on groundwater hydrograph

for all major sub-basins are required to make a direct verification. If there is not enough hydrograph, for the observation period or number of monitoring, so-called

“Passive Verification” shall be adopted.

The passive verification is a kind of compromised verification method, that is, if the groundwater level of model output keeps a reasonable range of depth in a certain sub-basin for enough long period such as more than 30 years or 40 years, it is considered the groundwater model of the sub-basin is properly constructed (it shall be explained later)

9． MODEL CONSTRUCTION

(a) Plane Model (Sub-basin Division) To construct a plane model is to sub-divide the target area into proper number of sub-basins (the unit basin for analysis). This procedure is the most important process, which determines almost all of the quality of the model such as the applicability and accuracy. Mathematical model of the Program is a “Differential Element Method”, so the number of the sub-basin division is the more, the better. However, it has a limit from the capacity of computer, for most of personal computer around 100 sub-division is the maximum for a while. Then, by the same reason, it is expected that every sub-basin has almost same area and same shape, of course as possible.

After the Sub-basin division, the relationship of all sub-basins shall clearly be defined: up and down stream relation in the surface system and connected or disconnected in the


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subsurface system. Some of the examples of sub-basin division are to be shown in the figure.

(b) Vertical Model After the sub-basin division was completed, each sub-basin is given its vertical structure. At first, the topographic cross-sections of all of river basins are taken; then, the boundary elevations and the representative elevation are examined. The former are the elevations of the upper and the lower ends of each sub-basin, and the later is the elevation of central part of the sub-basin which can represent the elevation of whole sub-basin, and the groundwater level is measured from this elevation.

After setting the sub-basin boundaries into the cross-section, the aquifer structure is to be consider such as an impervious foundation boundary, positions and thickness of aquicludes (bottom of unconfined aquifer), and so forth. However, even

in the multi-aquifer system actually, it has no meaning to set the multi-aquifer structure (separation of the unconfined and confined aquifer) when there is no groundwater hydrograph on each aquifer observed separately, because there is no way to verify the structure.

Inter-sub-basin connections are usually calculated as shown in the right figure, when the shapes or depths are considerably different. The image of vertical model stored in computer is just like as the left figure.


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(c) Allocation of Precipitation, Evapotranspiration In the case that the target area is not so wide and there is only one precipitation data set, the data set shall be applied in all sub-basins. When the target area is so wide and enough number of precipitation data sets is available, a typical precipitation data set shall be adopted in respective zones. For the data set on evapo-transpiration, the same consideration shall be taken.

(d) Current Water Intakes Current surface water intakes or groundwater withdrawals are other important water volumes to be considered in the water balance analysis. In general, to catch the exact volumes of current intakes from the surface system or groundwater discharges in total, for every sub-basin, is a little difficult. However, these volumes should be put into the analysis even though they are only estimations; excepting the case they are as small as negligible.


Sector 6-35

10. VERIFICATION OF THE MODEL

(a) Verification of Surface System Surface water system is usually modeled by a series of tanks, simply called as “Tank Model”. In the case of SSM (by the latest version), a new concept of “River System” is introduced. The tank model can simulate the recharge and surface flow-out system very well, however, the flow-out from a certain tank is spread out to the next tank (sub-basin), resulting the over estimation of evapo-transpiration. The SSM has a spring system, and the spring is usually come out into a river or it makes an origin of river. Thus, the model has both surface tank and river tank. Structure of the surface tank is consisted of two or three stories of tanks with orifices, usually one at the bottom and plural at the side. The bottom orifice means a percolation downward, and side orifices means a surface out-flow to the downstream. River system is modeled by a tank with bottom orifice and overflow notch. Inside of the river system is divided into some stories, and each story has a depth and flow rate. The bottom orifice indicates the percolation through the river bottom.

Verification of the surface system is, usually, carried out by so-called “Pattern Matching” as shown in the figure below. Calibration procedures are just “try and error approach”. A certain set of tank parameter such as number of orifices, runoff coefficient of each orifice, and infiltration coefficient, and run the program. Then, the outputs of the model and the actual records (verification data) are compared. If they are not matched, the parameters are


Sector 6-36

modified and run the program. In case of the latest version of SSM (it has a spring out system); the modification of spring out elevation is also one of the quite important factors of verification. Thus, the modifying of parameters is continued until the model outputs become almost same with the verification data.

When there is no snowfall data in the cold region, the pattern matching procedure can not be applied because the runoff pattern is delayed by snow and snow-melting. In this case,

so-called “Volume Matching” is to be adopted: to adjust the tank parameters through the volume of annual runoff of the basin, in the standard year. The outputs from the model in daily or monthly bases are not accurate in this case, but the surface structure can be verified roughly in yearly basis even though there is no snowfall data.

(b) Image of Subsurface System The image of subsurface system is shown left. The unconfined aquifer system is modeled with a series of open boxes connected through open conduit. As shown in the figure, the groundwater flow from a sub-basin (a box) to the next sub-basin (next box) is controlled by Darcy’s Law. Each sub-basin has groundwater table. While, the confined aquifer system is modeled with a series of closed

C.L C.L

l

b α=kb/l

h

h1 zh2

(1) IN CASE OF UNCONFINED AQUIFER

C.L C.Ll

h1

h2

b

t

(2) IN CASE OF CONFINED AQUIFER

α'=ktb/l


Sector 6-37

boxes connected through a pipe. There is no groundwater table in this case but only piezometric head. To verify the subsurface model, every permeability coefficient in every groundwater link is modified in accordance with its output and observation record.

As explained above, the unconfined aquifer has open groundwater table, and the water table in each sub-basin shall be decided through the balance of groundwater storage and Strativity of the aquifer. In the case of confined aquifer, there is no groundwater table but the piezometric head shall also be decided through the balance of storage and Strativity.

In the verification procedure, the value of Strativity shall also be modified in accordance with its output and the record.

(c) Verification of Subsurface System

The sub-basins which have groundwater hydrograph can be verified directly by “Direct Verification”, which is also a curve matching method as same as the pattern matching mentioned above. The following figure shows the direct verification result. In the figure, a thick line is actual observation and thin but sharp line shows the groundwater level by the model output.

Sub-basins those have no verification data but are seemed to have a similar structure with the one verified by Direct Verification can be applied the structure verified at other

h

q = λｖ

v = f(d)d = h - z

0(1) IN CASE OF UNCONFINED AQUIFER

h

h q = q 0 1 + S ( h - z )

0 q0 q(2) IN CASE OF CONFINED AQUIFER

z

q or v

h max

z

q m

ax

aquifer


Sector 6-38

sub-basins.

In the case there is few verification data for the target area, the Direct Verification can not be

applied. However, in this case the sub-basins are verified by so-called “Passive Verification”. The Passive Verification is a kind of compromised verification method, that is, if the groundwater level of model output keeps a reasonable range of depth in a certain sub-basin for enough long periods such as more than 30 years or 40 years, it is considered the groundwater model of the sub-basin was properly constructed. In case of the groundwater system, the modification of permeability coefficient of each groundwater link is the main works.

The groundwater level is going up when the permeability to the downstream link is reduced, and going down when the permeability is increased.

10． WATER BALANCE SIMULATION

(a) Simulation under current condition

When the model was calibrated under the current condition, the water balance simulation under the current condition is completed. The SSM calculates the infiltration (recharge), evapo-transpiration, surface runoff, river runoff, spring out, and current intakes under the daily rainfall for 40 years, to calculate the surface water balance.

The model calculates the recharging volume, groundwater level of each sub-basin, spring


Sector 6-39

out, groundwater inflow, groundwater outflow, volume of stored water, and current discharge volume by daily basis for 40 years, to calculate the groundwater balance.

(b) Simulation under natural condition

The SSM which was once verified under the current condition is to be modified to make a simulation under the natural condition, without pumping and without intake. The modification is quite simple, only the current discharge data and intake volume files are erased from the model. The model calculates again the surface water balance and also groundwater balance, in daily basis and for every sub-basin for 40 years (depending upon the period of input data). Outputs of the model, under the natural condition, indicate the maximum volume of surface water and groundwater existing in the target area.

Table 4.1.3 NATURAL WATER BALANCE

Area 92-01 Ave. Basin (Km2) Rain RunIn Spring Recharge Evap RunOff Intake

Kebir [1-5] 333.5 251,520 0 9,180 118,913 91,014 53,240 -2,467 Ostuene [6-9] 169.6 127,962 0 13,062 45,970 45,950 49,978 -875 Akkar [10-13] 133.1 100,429 0 13,437 44,305 32,646 38,269 -1,353 Bared [14-17] 266.3 200,761 0 138,488 114,204 59,346 167,123 -1,425 Abou Ali [18-22] 484.9 365,627 0 153,598 187,412 109,125 226,098 -3,411 Jouz [23-26] 186.3 137,862 0 11,468 69,876 45,991 35,100 -1,638 Ibrahim [27-30] 346.7 259,532 0 301,024 149,687 86,978 326,882 -2,991 Kelb [31-33] 254.9 192,166 0 117,496 69,621 63,056 178,751 -1,762 Beirut [34-37] 309.9 228,052 0 34,336 118,189 78,362 68,866 -3,029 Damour [38-41] 186.2 139,555 0 102,140 66,816 45,097 131,413 -1,630 Awali [42-45] 334.5 248,681 0 83,170 62,434 85,897 186,910 -3,389 Saintaniq [46-48] 161.9 116,582 0 2,653 68,955 40,787 10,993 -1,499 Zahrani [49-51] 104.1 75,831 0 8,947 48,152 26,282 11,462 -1,119 A Assouad [52-53] 160.1 112,279 0 5,665 63,712 48,952 8,259 -2,979 Litani [54-64] 2,231.3 1,661,272 0 584,914 1,317,408 662,952 280,971 -15,146 Assi [65-69] 1,848.8 1,393,617 0 153,074 686,114 469,108 396,868 -5,400 Hasbani [70-73] 587.4 442,789 0 11,305 203,224 160,240 92,895 -2,266 S.TOTAL 73 8,099.5 6,054,517 0 1,743,957 3,434,991 2,151,782 2,264,080 -52,379Percentage (%) 80.4% 100.0% 0.0% 28.8% 56.7% 35.5% 37.4% -0.9%Coastal Basin [74-97] 1,690.7 1,213,947 0 86,752 605,518 474,825 237,950 -17,594 Individuals [98-99] 286.0 215,575 0 94,871 138,318 68,736 107,029 -3,637S.TOTAL 26 1,976.7 1,429,522 0 181,623 743,836 543,560 344,978 -21,231.4Percentage (%) 2.8% 100.0% 0.0% 12.7% 52.0% 38.0% 24.1% -1.5%G.TOTAL 99 10,076 7,484,039 0 1,925,580 4,178,827 2,695,343 2,609,058 -73,610 Percentage (%) 100.0% 100.0% 0.0% 25.7% 55.8% 36.0% 34.9% -1.0%

30.1%

In Out SurfBal

Surface Water Balance

Table 4.1.2 CURRENT WATER BALANCE (Unit: 1,000 m3)

Area 92-'01 Ave. Basin (Km2) Recharge GInflow PmpUp SprUp GOutflow

Kebir [1-5] 333.5 118,751 0 30,147 38 114,687 -16,906 10,909,330Ostuene [6-9] 169.6 45,749 65,792 15,225 10,331 90,917 -20,216 3,942,469Akkar [10-13] 133.1 44,278 16,145 7,289 8,728 49,559 -16,167 2,971,683Bared [14-17] 266.3 112,912 45,218 27,867 111,835 30,183 -11,755 7,860,158Abou Ali [18-22] 484.9 187,479 98,569 18,413 159,877 123,450 -17,790 14,920,980Jouz [23-26] 186.3 69,852 6,708 4,825 9,983 74,616 -24,311 5,413,656Ibrahim [27-30] 346.7 149,276 197,813 9,660 282,647 63,088 -15,192 6,297,798Kelb [31-33] 254.9 69,512 119,864 10,544 106,203 87,096 -7,315 5,728,840Beirut [34-37] 309.9 118,119 18,409 9,025 28,427 119,991 -15,854 8,122,575Damour [38-41] 186.2 66,285 115,207 13,886 84,472 85,350 8,089 6,344,904Awali [42-45] 334.5 96,448 105,784 9,487 100,908 97,590 -5,752 6,211,775Saintaniq [46-48] 161.9 68,948 1,882 13,620 1,844 67,360 -11,995 4,650,250Zahrani [49-51] 104.1 48,119 11,019 3,680 7,346 54,588 -10,653 3,030,097A Assouad [52-53] 160.1 63,388 876 15,030 1,107 51,229 6,459 7,382,489Litani [54-64] 2,231.3 931,747 858 197,244 85,811 870,582 -221,032 78,590,310Assi [65-69] 1,848.8 683,504 58,698 119,292 73,595 715,287 -57,736 70,195,820Hasbani [70-73] 587.4 204,071 34,156 6,584 5,857 287,808 -62,022 23,107,250S.TOTAL 73 8,099.5 3,078,436 896,998 511,818 1,079,009 2,983,379 -500,148 265,680,384Percentage (%) 80.4% 100.0% 29.1% 16.6% 35.1% 96.9% -16.2%Coastal Basin [74-97] 1,690.7 605,034 168,117 92,756 58,007 675,378 -59,176 41,326,900Individuals [98-99] 286.0 137,750 106,971 6,511 85,020 180,815 -27,625 12,442,920S.TOTAL 26 1,976.7 742,784 275,088 99,266 143,027 856,193 -86,802 53,769,820Percentage (%) 2.8% 100.0% 37.0% 13.4% 19.3% 115.3% -11.7%G.TOTAL 99 10,076 3,821,220 1,172,086 611,084 1,222,035 3,839,572 -586,950 319,450,204Percentage (%) 100.0% 100.0% 30.7% 16.0% 32.0% 100.5% -15.4%

Groundwater BalanceIn Out Balance Volume


Sector 6-40

(c) Assessment of Water Resources Potential

The water volumes exist in the area, both for surface and groundwater, are calculated through the SSM simulation under the natural condition. They are just existing water volumes and they suggest the upper limit volume of the water resources but do not show the water resources development potential. In the case of surface water, the water resources potential can be calculated from the base flow of a certain river at the 10years return period of drought, and the development potential is the volume minus current utilized volume (which means already developed).

In the case of groundwater, the maximum resources volume is just same with yearly recharging volume in a 10 years return period drought year. However, the development potential of groundwater system must carefully be assessed basin by basin from the view point of sustainable development, and it is recommendable not to exceed 1/3 of the net yearly recharge volume.

For the coastal basins, the groundwater development potential must be less than the volume

Figure 4.3.1 CONCEPT OF GROUNDWATER POTENTIAL

Ground surfaceUnsaturated zone

Groundwater tableDevelopment Potential

Net Development Potential

Current Pumping Volume

Renewable Groundwater(Resources Potential in narrow meaning)

Existing Groundwater(Resources Potential in wide meaning)

El. -500m

Rainfall Evapotranspiration

Intake

100

RunoffAvailable water = 100+2,100+1,200 = 3,400 mcm/y

Spring Recharge 1,200

Groundwater-flow Pumping up

Available water = 600+2,700/3 = 1,500 mcm/y

700

Supplement from Storage

Figure 4.9 A Sample of Comprehensive Water Balance

Surface System

Groundwater System

7,500 2,700

2,100

3,800

2,700

600


Sector 6-41

which causes the drawdown of groundwater level to elevation 0m to avoid the sea water intrusion.

The left figures show a sample of pumping simulation at the coastal sub-basin. The first is a pumping pattern normally used in this region, mainly comes from an irrigation demand. The lower is simulation results with pumping pattern and water level calculated.

However, in the case of development of offshore submarine spring, the development potential can be the same volume with the groundwater outflow to the sea. The table in next page shows a sample of Groundwater potential assessment.

Basic Pumping Pattern

0 0 0

52.78

168.41

206.00194.63

215.97

130.49

31.72

0 00

50

100

150

200

250

Jan. Feb. Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

Pum

ping

Rat

e (T

CM

/mon

th)


Sector 6-42

Table 4 .3 .1 . (Unit: 1000m3 )

Basin Recharge Spring OutNet

Recharge

TotalDevelopment

PotentialExisting

W ithdrawal

NetDevelopment

PotentialKebir inland 113,782 9,180 104,602 34,867 18,412 16,455

coast 32,000 11,735 20,265Ostuene inland 36,502 13,062 23,441 7,814 4,633 3,180

coast 30,000 10,592 19,408Akkar inland 39,004 13,438 25,566 8,522 4,439 4,083

coast 17,000 2,849 14,151Bared inland 110,150 138,487 -28,337 0 26,309 -26,309

coast 7,000 1,559 5,441Abou Ali inland 140,767 153,598 -12,830 0 12,621 -12,621

coast 41,000 5,792 35,208Jouz inland 57,456 11,468 45,987 15,329 4,212 11,117

coast 42,000 613 41,387Ibrahim inland 134,761 301,024 -166,263 0 9,018 -9,018

coast 15,000 643 14,357Kelb inland 50,741 16,040 34,701 11,567 9,954 1,612

coast 100,000 590 99,410Beirut inland 114,167 34,298 79,868 26,623 7,170 19,453

coast 5,000 1,854 3,146Damouar inland 65,517 102,140 -36,623 0 12,481 -12,481

coast 15,000 1,205 13,795Awali inland 51,096 19,205 31,891 10,630 3,694 6,936

coast 62,000 5,792 56,208Saintaniq inland 63,957 2,653 61,303 20,434 5,928 14,506

coast 5,000 7,692 -2,692Zahran i inland 41,693 8,947 32,746 10,915 1,224 9,691

coast 40,000 2,456 37,544Abou Assouad inland 38,867 5,665 33,202 11,067 1,996 9,071

coast 32,000 13,034 18,966Litani inland 943,387 458,804 484,583 161,528 191,624 -30,096

coast 55,000 5,620 49,380Assi inland 686,114 153,072 533,042 177,681 119,292 58,389Hasban i inland 203,224 11,305 191,919 63,973 6,584 57,389Rivers Total inland 2,891,184 1,452,386 1,438,798 560,950 439,591 121,359

coast 498,000 72,027 425,973Oliant inland 2,132 0 2,132 711 24 686

coast 12,000 15,127 -3,127Abda inland 14,890 0 14,890 4,963 1,165 3,799

coast 5,000 3,190 1,810Minie inland 13,659 0 13,659 4,553 156 4,397

coast 3,000 6,702 -3,702Chekka inland 24,632 0 24,632 8,211 521 7,690

coast 55,000 1,491 53,509Batrouan inland 56,991 0 56,991 18,997 4,473 14,524

coast 24,000 1,949 22,051Jounie inland 17,230 0 17,230 5,743 256 5,487

coast 45,000 1,478 43,522Aaramoun inland 42,116 211 41,904 13,968 3,312 10,656

coast 13,000 525 12,475Barja coast 21,000 1,236 19,764Sarafand inland 28,777 0 28,777 9,592 933 8,660

coast 47,000 13,876 33,124Sour inland 115,906 0 76,472 25,491 4,360 21,131

coast 100,000 31,982 68,018Yammoune inland 99,629 9,478 90,151 30,050 6,300 23,751Kfer Kouk inland 38,688 85,393 -46,705 0 211 -211Non-R iver inland 454,649 95,083 320,133 122,279 21,711 100,568

coast 325,000 77,556 247,444

Groundwater Resources Development Potential


Sector 6-43

(d) Simulation under Development Scenarios Once the SSM has been constructed (and verified), it can be utilized as a decision making tools. If any kind of water resources development plan was raise up, the water volume required for the plan, a kind of resources (surface water or groundwater), and the location of intake (target basin) are put into the model and run the program for another 40 years (depends on data), using the existing rainfall set though. The model easily outputs the volume which can be taken out actually and the effects of such intake in the case of surface water development. The model also outputs the water volume can be pumped up and then the changing of groundwater level if such volume of groundwater was withdrawn. Thus, the planner can know the available water volume and effects of the water resources development roughly, before conducting a Feasibility Study.

12. FUNCTIONS OF SSM

12.1. Two-phases Density Flow (Sea-water Intrusion)

Two phases density flow consisted of sea water and fresh water, commonly seen near around a sea shore, can be simulated through SSM, under the condition that the aquifer is unconfined and these two phases shall not be mixed nor diffused each others. The image of two-phase density flow is shown as the following figures.

The behavior of fresh water, in a x-y plane rectangular coordinate, is expressed through the following differential equations (refer to the figure.);

h

Freatic Surface

hf

Fresh Water(ρf) Sea Level

qfx

x

Interfacehs

qsx

z

Sea Water

(ρs)

Aquiclude

y

Subbasin(4) ly(4)

lx(4)

Subbasin(1) Subbasin(0) Subbasin(2) ly(1) ly(0) ly(2)

lx(1) lx(0) lx(2)

Subbasin(3) ly(3)

lx(3)

x

h Subbasin(1) Subbasin(0) Subbasin(2)

hf(1)hf(0)

hf(2)=hs(2) ρf

Qfx1 ρf

k(1/0) hs(0) k(0/2)

hs(1)k(1/0)

k(0/2)

lx(1) lx(0)

lx(2)x

ρs

ρs

ρs

Qfx0

z(1)z(0)

Qsx1

z(2)Qsx0


Sector 6-44

( )

( )

− = + +

= − ⋅ ⋅

= − ⋅ ⋅

λ∂∂

∂∂

∂∂

ϕ∂∂

ϕ∂∂

hft

qfxx

qfyy

R

qfx k hf hs fhfx

qfy k hf hs fhfy

LLLLLLLLLLLLLL

LLLLLLLLLLLLLL

6

7

( )

( )

The upper one (6) is so-called “Continuity Equation”, and the lower two (7) define the condition of movement.

While, the behavior of sea water phase is, in the same manner with above, expressed as follows;

( )

( )[ ]

( )[ ] ( )

− = +

= −⋅ + −

= −⋅ + −

λ∂∂

∂∂

∂∂

∂ ϕ ϕ ϕ∂

∂ ϕ ϕ ϕ∂

hst

qsxx

qsyy

qsx k hs zf hf s f hs

x

qsy k hs zf hf s f hs

y

LLLLLLLLLLLLLLL

LLLLLLLL

8

9

( )

( )

where qfx qfy, : flow vectors of fresh water qsx qsy, : flow vectors of sea water

k : permeability (same for fresh & sea water, and same for x and y direction)

ϕ ϕf s, : specific gravity of fresh & sea

water R : Supplement to fresh water

Adding the equations of (6) and (8) above mentioned, the following equation is resulted;

( )10LLLLLRy

qsyx

qsxy

qfyx

qfxt

hst

hf++++=⎟⎟

⎠

⎞⎜⎜⎝

⎛+−

∂∂

∂∂

∂∂

∂∂

∂∂

∂∂λ

As shown in the figure, when the target groundwater basin was divided into optional quadrangular unit basins (sub-basins), with average widths of l lx y, in major two dimensions, the water

balances of both fresh and sea water in a certain quadrangular pillar (of the unit basin) can be calculated through the equations of (7) and (9). Then, based on the changes of storage volume of

them, water heads of fresh water (hf) and sea water (hs) at a definite time (Δ ′t ) later can be


Sector 6-45

obtained.

The equations of (7) and (9) can be solved through differential solution. Using the marks in Figure 5.2., the derivative of qfx is expressed as follows;

( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )

( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) 20/20

2022001101/01

010011:

20

01

xxhfhffyyhshfhshfkQfxo

xxhfhffyyhshfhshfkQfxi

where

QfxoQfxix

qfx

ll

ll

LLLLll

ll

+−

⋅+⋅−+−⋅=+−

⋅+⋅−+−⋅=

−=

→

→

ϕ

ϕ

∂∂

And for sea water;

( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) [ ] ( ) ( ) ( )

( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) [ ] ( ) ( )

∂∂

ϕ ϕ ϕ

ϕ ϕ ϕ

qsxx

Qsxi Qsxo

Qsxi k hs z hs z y y

f hf hf s f hs hs x x

Qsxo k hs z hs z y y

f hf hf s f hs hs x x

= −

= ⋅ − + − ⋅ + ⋅

− + − − +

= ⋅ − + − ⋅ + ⋅

− + − − +

→

→

1 0

0 2

1 1 0 0 1 0

1 0 1 0 1 0 12

0 0 2 2 0 2

0 2 0 2 0 2

l l

l l L

l l

l l

/

/

In the same manner, the derivatives for y direction also be obtained, and thus, the right side of the equation (10) shall be solved.

12.2. Cutoff Wall (Underground Dam)

In the storage model, a storage coefficient between neighboring two unit basins (sub-basins) is, as expressed by the equation (3), equal to the quotient of averaged Transmissivity of the two basins divided by center to center distance. Herein, the effectiveness of cutoff wall which set in between these two unit basins is to be evaluated.


Sector 6-46

As illustrated in the figure, when the permeable area (A) of each section is approximately same, the groundwater flow (q) from a-section to c-section and the flow from c-section to e-section shall also be nearly same and expressed by the equations below;

( )

( ) ( )

q k Ah h

q k Ah h

= ⋅ ⋅−

= ⋅ ⋅−

11 2

1

22 3

2

13

l

lLLLLLLLLLLLLLL

Where k k1 2, are the permeability of sub-basin (1) and (2). These are modified to;

( )

h hqk A

h hqk A

1 21

1

2 32

2

14

− =⋅⋅

− =⋅⋅

l

lLLLLLLLLLLLLLLLL

Then, these two were added and resulted into;

( )

( ) ( )

h h qA k k

q

k k

A h h

1 31

1

2

2

1

1

2

2

1 3

15

1 16

− = +⎛⎝⎜

⎞⎠⎟

=+

⋅ ⋅ −

l lLLLLLLLLLLLLL

l lLLLLLLLLLLLL

Thus, the averaged permeability k’ between a- and e-sections is equivalent to;

Subbasin(1) Subbasin(2) Basin center Basin center

l(1) l(2) l(3)

Cutoff Wall

h(1)

h(5) h(3)

k(1)k(2)

a b d e

h(6)

c

h(4)

h(2)

k(3)


Sector 6-47

( )′ =+

+k

k k

l l

l lLLLLLLLLLLLLLLLLL1 2

1

1

2

2

17

And when a cutoff wall has set in between these two sub-basins, the condition of water flow is expressed, in the same manner with above, as follows;

( )h h

qk A

h hqk A

1 41 3

1

4 53

3

2− =

−⋅

− =⋅⋅

l l

l

( ) ( )h h

qk A5 62 3

2

218− =

−⋅

l lLLLLLLLLLLLLLL

Adding above three equations and re-arranging of the result shall lead into the following equation;

( ) ( )q

k k k

A h h=−

+ +−

⋅ ⋅ −1

2 219

1 3

1

3

3

2 3

2

1 6l l l l lLLLLL

Consequently, the average permeability k” from a- to e-section through the cutoff wall (b- to d-section) shall be calculated out as shown below;

( )′′ =+

−+ +

−k

k k k

l l

l l l l lLLLLLLLLLL1 2

1 3

1

3

3

2 3

2

2 220

13. CONBINATION USE WITH OTHER SIMULATION MODEL

As mentioned above, when SSM is built up, with accurate enough and reliable data sets, the model outputs can give appropriate water balances of both surface and groundwater, and further, they can offer the boundary conditions of other detailed mathematical model simulations (or potential solution) through FDM or FEM, e.g. “MODFLOW” or “GMS”.

The most popular case of the combination use of SSM in the groundwater model simulation is the combination with “MODFLOW” or “MOD-PATH” application (USGS), as shown in the following figure.


Sector 6-48

To solve the equation through FDM or FEM, the following three types of boundary conditions are required17):

b) Dirichlet’s Boundary (no-flow boundary)

There is no flow ( 0=∂∂

nh ).

c) Neumann’s Boundary Inflow (or outflow) value is known.

d) Steady Head Boundary The water head is steady and known.

Those boundary conditions, especially b) and c) conditions, are obtained from the outputs of SSM, and further FDM solution can be conducted9).

14. SSM PROGRAMME

14.1. History

The original simulation program for SSM, developed by Mr. M. Yoshikawa at 1977, was written by FORTRAN-IV and it was just for main frame computer. For rather long time, this kind of simulation was analyzed through the SSM on the main frame computer.

According to the drastic improvement of the ability of a personal computer, the simulation program


Sector 6-49

was transferred into MS-FORTRAN, to operate it on the desk-top personal computer on 1991. Continuously, the program was progressed, and then, the “Visual Basic Version” on Windows 95 has been developed recently, because of the easiness to treat a graphical interface.

14.2. Flow Chart

The process of simulation study, a flow of the program is shown in the Figure 14.1. As shown in the Figure, the simulation program itself is consisted of two parts named “Super” and “Sub”, treating for surface and subsurface system respectively. And actually, the simulation process is divided into three steps of a) Preparation, b) Run Super program, and c) Run Sub Program.

As mentioned before, since the SSM simulation is basically curve fitting method through trial runs, the major works in the simulation is a repeating of an adjusting the parameters and run to compare the result. Thus, the main routines for the simulation are shown by double-line. In this connection, the program of Visual Basic Version is fully contrived for easiness to compare the simulation output (response from the model) and the verification data in both routines.

Those three steps mentioned are to be explained roughly, at the following sections, and the detail on actual operation shall be presented as an operation manual, attached in the paper but separately.

14.3. Preparation Works

Before running the program, several data files must be prepared; those are meteorological data, verification data, and model structure files. In the case of pumping simulation, the pumping pattern file is required besides them.

The required meteorological data are;

Figure 8.2.1 FLOW CHART ON SSM SIMULATION

Denied NO

YES

NO YES

Start

Formulating of try-file, ini file

Preparation ofdata files

Verification ofSurface System

Construction ofSurface Medel

Construction ofSubsurface Medel

Verify

Verification ofSubsurface System

Verify

Run "Sub"subroutine

Modify theparameter

Identify Current WaterBalance

Run withoutintake/pump-up

Identify Natural WaterBalance End


Sector 6-50

- Rainfall (daily base, as long as possible), - Evapotranspiration potential (monthly base, same duration with rain), - Tidal data (daily in average, as long as possible).

As the verification data for a surface system, daily surface runoff data of any surface drainage, as many points and long period as possible, shall be required. If any reservoir dam(s) be exiting, the monitoring data of reservoir water elevation (with H-Q curve) or inflow data, intake amount, and spilling amount, shall be one of the verification data. And as the verification data for a groundwater system, groundwater monitoring data in daily base (or weekly base), for each aquifer system if there are plural aquifer systems, are to be prepared in a certain format.

Initial model structures, for both surface and groundwater systems are arranged and described in so-called “ini-file” (the file with suffix of *.ini). The details of the file and its format are shown in the Manual but it contains the names of meteorological data files prepared, the number of surface and groundwater sub-basins, the tank structures for a surface system, the aquifer structures for a groundwater system, the current pumping amount through existing wells if any, etc. Besides those, the ini-file has information on graphic display. In the case to make a pumping simulate, information on cutoff wall and pumping shall also be described here.

So-called “try-file” which has the same name with the ini-file but followed by the suffix of “try” also is prepared. The file defines the detail of surface tank structure such as the number and heights of orifices, the runoff coefficients of them, and so forth. The prototype of the try-file shall be constructed by the Surf program automatically, and the detail of contents shall be modified when the trial run started.

14.4. Trial Run

In any case, the simulation study is to be started from the calibration of the model constructed, and then, the effectiveness of cutoff, the condition of sea water intrusion, or the groundwater behavior under pumping shall be simulated if they are required. As the major works in the calibration of the model, trial runs of several hundred times or more shall be repeated until the response of the model fits to the verification model. Basically, two times of calibration works are required; once for the surface system, and once for the groundwater system.

The calibration of surface system, through Super Program, is to be conducted at first, and the groundwater recharge file (so-called q-file) shall be created through the Super based on the surface tank model calibrated. Then, the trial run of Sub Program is to be carried out. The program calculates the groundwater level of each sub-basin in daily base (or more finite depending upon the request) based on the sub-basin structures, aquifer parameters, and the recharging amount from the surface system which are defined in the q-file. The trial run is also repeated until the response of


Sector 6-51

the model fits to the groundwater monitoring data.

Sometimes, it may need to modify the surface tank model again when the model response based on the recharging file can not fit to the actual data any more. In this case, it’s need to leave the Sub Program at once, and the surface model must be reconsidered again.

After completion of the calibration work, the simulation of groundwater behavior or total water balance under several conditions shall be carried out, according to the purpose of the study. In the case of underground dam scheme, a condition of cutoff is to be set in the ini-file, and the conditions of intake facility such as the position, pumping rate, etc., must be defined in the ini-file in the case of pumping simulation.

14.5. Reporting & Printout

The program creates several files as the result of calculation, those are; “q-file” for recharge, “p-file” for groundwater runoff, “h-file” for groundwater head of each sub-basin, “gio-file” for total water balance, “uio-file” for groundwater balance under pumping condition, and so forth. And these are available to summarize and report the results of simulation.

Besides the files created through the program run, the structures of surface tank, and calculated and/or actual groundwater hydrograph can be printed out as a color graph through Super and Sub Programs respectively.


Sector 6-52

2.3. Geophysical Prospecting

2.3.1. Main Text 1.

The Study

0n Groundwater Development Resources Potential

in Kabul Basin

in the Islamic Republic of Afghanistan

Capacity Development Plan on Groundwater

Development

G E O P H Y S I C A L P R O S P E C T I N G

TEXT 1

GEOPHYSICAL PROSPECTING

FOR

GROUNDWATER SURVEY

SEPTRMBER 2008

JICA STUDY TEAM


Sector 6-53

CONTENTS

I INTRODUCTION........................................................................................ 6-54 II SUMMARY OF GEOPHYSICAL PROSPECTING ................................ 6-54

1 SEISMIC REFRACION PROSPECTING........................................... 6-54 2 SEISMIC REFLECTION PROSPECTING......................................... 6-58 3 ELECTRIC REFLECTION PROSPECTING..................................... 6-60 4 ELECTROMAGNETIC PROSPECTING........................................... 6-61 5 GRAVITY PROSPECTING................................................................... 6-66 6 RADIOMETRIC ELECTRIC PROSPECTING ................................. 6-67

III REFARENCE ............................................................................................... 6-68


Sector 6-54

I INTRODUCTION

The geophysical prospecting has been applied for groundwater exploration to define the hydrogeological structure such as, 1) Subsurface general geological structure, 2) Depth to aquifer and thickness of aquifer, 3) Distribution, strike and inclination of fault, 4) Depth to bed rock, 5) Cracks and fissures of rocks, applying their difference of geophysical characteristics.

Most efficient and direct method to confirm hydrogeological characteristic and capacity of aquifer, quality of groundwater etc is borehole digging with geophysical logging and pumping test. However by the economical limitation, geophysical prospecting is proceeded to borehole digging to estimate widely, approximately and indirectly hydrogeological structures. Frequently applied methods of geophysical prospecting are electric, electromagnetic, gravity and seismic prospecting.

In this seminar at first, type and outline of geophysical prospecting will be explained. Then electric prospecting method will be explained in detail with on the job training (OJP) of vertical electric survey (VES) using the Model 3244 specific earth resistance tester.

The schedule of the seminar will be: The first day is general explanation of geophysical prospecting and explanation of electric prospecting in detail. The second and the third day is OJP of VES on field. The final day is explanation for analysis of survey data and, interpretation and application of survey result.

II SUMMARY OF GEOPHYSICAL PROSPECTING

1 SEISMIC REFRACTION PROSPECTING

Seismic prospecting aims to analyze geological structure of underground defining elastic wave velocity of each rock/geology. Seismic refraction is applicable in area where the deeper layers, such as bedrock, have higher seismic velocities than the overlying layers.

There are tow types of body waves, namely compression or P-wave and shear or S-wave. P-wave is generally used for most near surface seismic refraction survey, because they are much easier to generate than S-wave. The applicability of the seismic refraction can be usually determined from an assessment of existing geological information. The estimation of the seismic velocity in each layer is combination of factors, such as rock type, compaction, degree of weathering/alteration, cracks, etc. Seismic refraction can determine depth of bedrock and generally useful for groundwater survey to analyze out line of deeper geological structure such as basin structure in Kabul basin.

Seismic refraction records seismic signal which have been returned to surface after having undergone refraction at the boundaries between layers with different seismic velocities.


Sector 6-55

The typical configuration for a field system is shown in Fig.1.1.

Explosives are normally used as seismic soured because of their high-energy output. Therefore it is required to obtain permission of blasting.

Data processing and analysis is conducted usually following procedure

Measurement of first arrival travel time

Preparation of travel time curve

Examination and adjustment of travel time data

Preparation of velocity profile

Fig.1.2 shows an example of travel time curve and velocity profile.


Sector 6-56

The final product of seismic refraction is velocity profile prepared by the analysis. It is essential to estimate the likely subsurface conditions using correlation between seismic velocities and various geological and geotechnical parameters, as well as available information on the local geological conditions. Fig.1.3 shows the relation between effective porosity and P-wave velocity of rocks. The seismic velocity increases with decreasing porosity. Fig.1.4 shows the approximate P-wave velocity of each rock.


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2 SEISMIC REFLECTION PROSPECTING

The seismic reflection was developed as a geophysical tool mainly for the field of oil and gas exploration, whose depth of investigation is typically several thousands of meters. On the other hand, shallow seismic reflection has been developed for civil engineering, and for prevention of earthquake disasters, especially for characterization of active faults (especially buried ones). It depth of investigation is usually from several tens to several hundreds of meters.

When seismic waves (P- or S- waves) generated on the surface reach a boundary in acoustic impedance, they will undergo refraction, transmission and reflection. Some of the energy reflects back to the surface. The seismic reflection makes use of the reflected wave to image the subsurface (Fig.2.1).

Acoustic impedance is a physical property of rock, equal to seismic velocity multiplied by density. Boundaries with greater acoustic impedance contrast will generate larger reflected waves.


Sector 6-59

The main purposes of the shallow seismic reflection are as follows:

1) To visualize subsurface structure as a seismic reflection profile and then to study geological structure and physical properties of the formation. Hydrogeological properties of formation also can be analyzed through reflection profile.

2) To be able to image a low velocity layer underneath a higher velocity one that can not be detected by the seismic refraction.

After data processing and interpretation the seismic reflection depth section is prepared.


Sector 6-60

3 ELECTRIC PROSPECTING

There are several methods of electrical survey including the resistivity method, spontaneous potential (SP) method, induced polarization (IP) method, and so on.

The spontaneous method: is mainly applied for investigation of groundwater flow or sulfide bodies by measuring distribution of electrical potential in the ground arising from natural causes.

The resistivity method: is based on transmitting current into the ground through electrodes, and measuring the electrical potential with electrodes to determine the electrical resistivity properties of the earth.

The induced polarization method: is used for determining other ground parameters by measuring the secondary electrical potential produced after a constant-current transmitted into the ground is turned off, or in the frequency domain by measuring changes in phase and amplitudes with frequency. This method mainly use for metallic ore deposit investigation.

For groundwater survey, the resistivity method is most widely used technique. This method can be of form of horizontal profiling, vertical sounding and two-dimensional prospecting 8such as high-density electrical prospecting, resistivity imaging method, etc.

Similar to the resistivity method, the electromagnetic survey is used to determine the electrical resistivity distribution of the ground, and is described in a separate chapter.

Schematic diagram of the resistivity method is shown on Fig. 3.1


Sector 6-61

The resistivity of the grounds changes due to the type of soil and rocks, porosity, water saturation, resistivity of the groundwater, amount of clay minerals produced by weathering and alteration, temperature and so on.(see Table 2.1). For example, generally, if the resistivity of groundwater (pore water) is lower caused by salt water contamination, resistivity of rock and soil changes to the lower, and if degree of water saturation is higher resistivity of rock and soil changes to lower.

The penetration depth of the resistivity method is usually up to around 300 meters depending on the used survey equipment, geological conditions and so on. For deeper surveys, it is recommended to use other method such as electromagnetic survey.

More detail for resistivity method such as selection of survey method, electrode configuration, survey line, equipment, procedure of field operation, data processing, analysis and interpretation is explained on another chapter.

Table 2.1 The relation between rock and soil conditions and resistivity (S.E.G..J 2000)

Conditions

Change of rock & soil resistivity

Low →

High

Remarks

Resistivity of groundwater and pore water

Low → High

Salinity, salt water wedge

Degree of water saturation High → Lower

Groundwater

Porosity (saturated) High → Lower

Clay fraction Many →

Few Soil type

Degree of weathering and alteration

Strong →

Slight

Temperature High → Low

Geothermal

4 ELECTROMAGNETIC PROSPECTING

The electromagnetic prospecting (defined as EM prospecting) is a geophysical exploration technique to investigate sub-surface electrical conductivity or resistivity distribution, similar in some ways to the electrical resistivity method.

EM prospecting is applied for exploration deeper targets such as groundwater, geothermal, hot spring because of measurement availability with large penetration depth, simple manner of measurement and availability for two-dimension analysis with computer. On the


Sector 6-62

other hand, EM methods are not suitable, in general, for survey near power lines, telecommunication lines, radio stations, factories, power plants, urban are and so on since electromagnetic waves radiated from these constructions and metallic objects influence the EM measurements. .

Typical EM methods for groundwater survey are as follows:

CSAM (Controlled Source Audio-frequency Magneto-Telluric)

TEM/ TDEM (Transient Electromagnetic/ Time Domain Electromagnetic)

Loop-Loop (SLINGRAM)

Each characteristic of these method such as application, survey depth, analysis method and so on is explained as follows: .

4-1 CSAMT and TEM/TDEM

In CSAMT and TEM stratified resistivity layers below the measurement points are generally sounded similar to vertical electric resistivity (VES) soundings. The penetration depths are normally around 1000m deeper than VES. They are suitable for reconnaissance of geological and hydrogeological structure below hundred meters from ground surface.

The CSAMT and long-offset TEM have deeper penetration and required fix large scale source of transmission out of the survey area. In case of TEM, some kind of loops are distributed as transmitting and receiving coil (refer to Fig. 4.1 and Fig.4.2). In the JICA study, TDEM was introduced as main geophysical prospecting and 200 survey points are conducted. Equipments introduced the study were TEM-47 for shallow prospecting upper 200m, TEM-57 for middle depth around 400m, and TEM-67 for deep prospecting of more than 600m. Spreading of a transmitter loop was 100m x 100m square as a rule. Even such rather large loop, enough exact response from the earth could not be obtained from some measuring points because of buried pipes, metal scraps on the ground, high voltage power lines passing near by, or high power radio stations every where. Trials to enlarge transmitter loop to get more strong and deep response were almost in vain because not only private housings but many security-concern organizations, international donor organizations, official and governmental agencies were occupying wide areas enclosing by high wall, especially in North Kabul, Pol-e-Charkhy, and Darlaman areas. However, around 80 % of all measuring points can be analyzed in enough accuracy.


Sector 6-63

In the JICA study all of the measurement records were interpreted into a combination of “Time-Resistivity Curve” and “Geo-electric Section” Combination figures of these two are shown as Fig.4.2.1. All of the Geo-electric sections are consisted of major three portions; the surface, the middle, and the base layers. All of the Geo-electric sections are consisted of major three portions; the surface, the middle, and the base layers. In almost all of the


Sector 6-64

analysis, the surface layer means Alluvial Deposits considered from their position, depth and apparent resistivity. Also in most of the cases, the middle layers, are consisted of two or three, some times much more sub-layers and considered to be Neogene in the Kabul basin.

As a result of the TDEM interpretation the maps of supposed isobathic contours of bedrock were made as Fig. 4.2.2.

0 . 1 1 1 0 1 0 0

1

1 0

1 0 0

1 0 0 0 N K - 1

A p p a r e n t R e s i s t i v i t y ( O h m - m )

T i m e ( m ) 1 1 0 1 0 0 1 0 0 0

4 1 0

1 0

1 0 0

1 0 0 0

D e p t h ( m )

R e s i s t i v i t y ( O h m - m )

U . T O N E

0 . 0 1 0 . 1 1 1 0 1 0 0

1

1 0

1 0 0

1 0 0 0 N K - 2 - 1

A p p a r e n t R e s i s t i v i t y ( O h m - m )

T i m e ( m ) 0 . 1 1 1 0 1 0 0 1 0 0 0

1

1 0

1 0 0

1 0 0 0

D e p t h ( m )

R e s i s t i v i t y ( O h m - m )

U . T O N E

Fig. 4.2.1 TDEM Time-resistivity curve& Geo-electric section (3rd

JTC)


Sector 6-65

4-2 Loop-Loop method

Loop-Loop method (also known as the Slingram method) is introduced as a kind of horizontal profiling for shallow portion of subsurface by potable equipment shown in Fig.4.3. This method has been applied for exploration of conductive ore-bodies and also for to map fault and shear zones for groundwater exploration.

5 10 15 20 25 30 1 0

1 5

2 0

2 5

3 0 Figure-3. By TDEM, Step-1 Fig.4.2.2 Iso-bathic contour of bed rock


Sector 6-66

5 GRAVITY PROSPECTING

The gravity prospecting is a method by which the subsurface density distribution is estimated from observed gravity anomalies (Bouguer anomalies), and the subsurface geological structure is inferred from the density distribution. In the gravity prospecting, generally, the term “gravitational acceleration” and “absolute gravity value” are used interchangeably, while “gravity anomaly”, and “Bouguer anomaly”, and “gravity value” are used for values calculated from observations.

The gravity prospecting has conventionally been used for large scale investigation of subsurface structure, such as in sedimentary basin survey for oil, natural gas and coal resources, and also large scale groundwater basin structure survey.

Examples of interpretation of gravity prospecting shown as Fig.5.1 and 5.2


Sector 6-67

6 RADIOMETRIC ELECTRIC PROSPECTING

Radiometric survey method can be used to detect geological anomalies such as fault or shear zones by measuring changes in intensity of natural radiation from the earth’s surface. Gamma rays are generally used in radiometric surveys for geological applications and the method has been used for the siting of boreholes for development of either groundwater or hot spring resources associated with fracture zone.

Car-borne survey is generally used for groundwater investigation. The method is conducted along roads with spectrometer equipment mounted on a motor vehicle.

The result of the survey is shown as gamma ray profile see Fig. 6


Sector 6-68

III REFARENCE

Seminar texts are arranged referring following texts, manuals and handbooks. The text for outline of geophysical prospecting and electric prospecting are made mainly referred with “Application of geophysical methods to engineering and environmental problems by The Society of Engineering Geophysicists of Japan (S.E.G.J.). The text for O.J.T arranged mainly by “Instruction manual for Model 3244 Specific Earth Resistance Tester” by Yokogawa M&C corp..

1) S.E.G.J.: Application of geophysical methods to engineering and environmental problems, 2000

2) S.E.G.J: Handbook for geophysical prospecting (Japanese), 1998

3) Yokogawa M$C corp.: Instruction manual Model 3244 Specific Earth Resistance Tester

4) K. Shimizu and S. Kawasaki: Hydrogeological Study of the Soraku Hill in Kyoto Prefecture (Japanees), Engineering Ge0logy 17-2 1976

5) Rowland B. French, P.D., R.G.; Time-Domain El electromagnetic Exploration, Northwest Geophysical Associates, Inc


Sector 6-69

2.3.2. Geophysical Prospecting, Main Text 2

The Study


in Kabul Basin



Development


TEXT 2

ELCTRIC PROSPECTING RESISTIVITY METHOD

FOR

GROUNDWATER SURVEY

SEPTRMBER 2008

JICA STUDY TEAM


Sector 6-70

CONTENTS

1. Selection of survey method...................................................................................... 71

2. Electrode configuration ........................................................................................... 71

3. Penetration depth, selection of survey line and survey point ............................... 72

4. Electrode spacing ..................................................................................................... 73

5. Equipment................................................................................................................. 73

6. Procedure of field operation.................................................................................... 74

7. Analysis ..................................................................................................................... 74

8. Interpretation ........................................................................................................... 75

9. Outcome and report................................................................................................. 75


Sector 6-71

1. Selection of survey method

The resistivity method includes vertical sounding, horizontal profiling and two-dimensional prospecting (refer to Fig. 1.1.). Vertical sounding is a cost-effective method to investigate the vertical resistivity distribution when subsurface structure is comprised of nearly horizontally layers. Horizontal profiling is used for surveying horizontal discontinuities in near surface formation such as fault and dyke rock. Two-dimensional prospecting is a survey method that combines vertical sounding and horizontal profiling, and is used for investigation of two-dimensional distribution of resistivity.

.

2. Electrode configuration

Typical electrode configurations used for resistivity method are Wenner array, Scchlumberger array, dipole-dipole array, pole-dipole array, pole-pole array and so on (see Fig.1.2). The Wenner and the Schlumberger are most commonly used for vertical sounding. The Wenner, the pole-dipole and pole-pole and dipole-dipole are suitable for horizontal profiling. For two-dimensional prospecting, the Wenner, dipole-dipole and pole-pole are commonly used.

The Wenner is an appropriate electrode configuration for shallow survey, while the Schlumberger is more suited for deeper survey. The pole-pole is popular due to its ease of operation when many measuring points are required.

The resistivity value ρa measured by various type of electrode configuration can be calculated with following equation using measured current I and potential V.

ρa = G*(V/I)

Where G is called “Geometric factor”, and it is a coefficient determined by type of electrode array, electrode spacing (a) and separation factor (n) (see Fig.1.2.). The resistivity calculated here is called apparent resistivity since it means average resistivity.


Sector 6-72

3. Penetration depth, selection of survey line and survey point

Sounding depth (Plot point of apparent resistivity: “a” in Fig. 1.2.) depends on spacing between potential and current electrode. In case of Wenner array, “a” is just spacing


Sector 6-73

between each electrodes but in case of Schlumberger array “a” is half length of spacing between outer electrode A and B. The maximum penetration depth for vertical sounding or two-dimensional prospecting is generally assumed to be one-fifth of spacing between the outer electrodes used for each measurement (see Fig. 1.3.).

For the case that the target depth is more than 100meters deep, resistivity sounding may be less practical since the penetration depth and length of survey line will be considerably longer.

In case of vertical sounding, it is better to select direction of survey line along the direction to keep topographically flat or/and geologically uniform. For example, in case of alluvial plan along river, survey line should be selected along river course.

In case of vertical sounding, space of survey point is planned considering horizontal change of subsurface geology and required accuracy of investigation.

4. Electrode spacing

In vertical sounding, the electrode spacing is expanded from center of survey line increasing penetration depth. In this case, progress of spread is generally arranged as a logarithmic increase. For example; in case of the Wenner array; “a” is arranged; 1m to 10m each 1m, 12m to 30m each 2m, 34m to 70m each 4m, 80m to 200m each 10m.

5. Equipment

Resistivity equipment consists of a transmitter and power supply, resistivity meter units, electrode, cables and so on. Model 3244, Specific Earth Resistance Tester is now using for resistivity survey by DGEH. This equipment was introduced by JICA expert Mr. Sugino and now was discontinued production. In the field demonstration of resistivity method will be operated by this equipment. Now some types of equipments for resistivity method have


Sector 6-74

been developed for example,:

SYSCAL (Kid, Junior, R1 PLUS, R2). (IRIS, France)

McOHM-EL (OYO, Japan)

TERRAMETER SAS1000/VES (ABEM, Sweden)

6. Procedure of field operation

The field operation is carried out in order of setting survey lines and stations with the topographic survey, installing electrodes and spreading cables, measuring, clearing equipment away finally.

In installing electrodes, special care should be taken to minimize ground contact resistance between the electrode and the earth. As occasion demands ground contact resistance may be reduced by use of several stakes as an electrode, water sprinkled over the electrodes or use of bentonite mud.

Cable should be connected tightly to electrodes, and the junctions should not be in connect with the surface since it may cause leakage of current.

During the measurement, the measurement data should be monitored in oder to chech the acquired data is of adequate quality. When abnormal data is found, the measurement should be repeated.

During and just after the measurements, it is important to judge the quality of the acquired data by brief evaluation of the measurement result on site.

Attention to accidental electtic shocks should be paid during measurement, since high voltage is impressed to electrodes and a high electric current flows though cables.

7. Analysis

For vertical sounding, it is possible to determine the resistivity of each layer and its boundary depth from an apparent resistivity curve. The graphical analysis method (curve fitting method) using master curves or one-dimension analysis (linear filter method) using computer is generally used in data analysis.

The curve fitting method can be used to determine resistivity and thickness of each layer successively downward from the top layer by considering measured result (curve), master curve (theoretical curve of apparent resistivity for horizontal two-layer model) and auxiliary curve (which converts upper two layers to one equivalent layer for three-layer model). However graphical methods have largely been replaced by computer methods such


Sector 6-75

as the linear filter method). The linear filter method assumes an initial resistivity model, and then iterates to obtain a final resistivity image by minimizing residuals between calculated and measured potential values.

In two-dimensional prospecting, it is common to calculate the resistivity section below survey by two-dimensional resistivity analysis. Two-dimensional resistivity analysis is performed by iterative inversion method (non-linear inversion method) using computer. This method simulates the measuring conditions on site as an analysis model, then adjusts the resistivity model so that theoretical value agree with measured value. The final resistivity section when convergence conditions are satisfied should be displayed with color-filled contour. Typical methods of theoretical calculation are Finite difference method, Finite element method, alpha-center method, and so on.

8. Interpretation

Generally, it is difficult to make a unique interpretation of geological/hydrogeological structure by its resistivity distribution. Therefore, it is important to review existing materials prior to interpretation of survey result. Typical useful materials are report of geological/hydrogeological observation on surface ground, result of drilling survey, geological and geophysical logging data, other geophysical survey result and so on. Specially, resistivity logging data are important. Resistivity of groundwater, rock and soil samples should be measured. The resistivity range for major minerals, rocks, and soils etc. shown in Fig.1.4 shows the ranges of resistivity at various soil and rocks.

9. Outcome and report

The following outcomes should be included in the survey report

(1) Outline of the survey (with survey layout map) (2) Methodology and equipment used

(3) Output image (in case of vertical sounding; ρa－a curve) (4) Survey result (with geological/hydrogeological profile and iso-bathic map)

In vertical sounding, for example of output image, ρa － a curve with analyzed result is shown like a style of drilling log (Fig. 1.5), comparison between analyzed resistivity and geological logging is shown as Fig.1.6. and geological/hydrogeological profile is shown as Fig.1.7.


Sector 6-76


Sector 6-77


Sector 6-78


Sector 6-79

2.3.3. Geophysical prospecting, Text 3. Operation Manual

The Study


in Kabul Basin



Development


TEXT 3

OPERATION MANUAL

FOR

MODEL 3244 SPECIFIC EARTH RESISTANCE

TESTER

SEPTRMBER 2008

JICA STUDY TEAN


Sector 6-80

CONTENTS

1. INTRODUCTION................................................................................................... 81 2. SPECIFICATION ................................................................................................... 81

2-1 System............................................................................................................... 81 2-2 Specification ..................................................................................................... 81

3. OPERATING PRINCIPAL OF TYPE 3244.......................................................... 82 4. CONSTRUCTION .................................................................................................. 83 5. OPERATING PROCEDURE................................................................................. 85

5-1 Measuring Procedure for Specific Resistance Prospecting.......................... 85 5-2 Measuring `rocedure for Specific Resistance Logging ................................. 86 5-3 Operational Note and Maintenance ............................................................... 86

6. ANALYTICAL PROCEDURE FOR SPECIFIC RESISTIVITY PROSPECTING (WENNER ARRAY) ............................................................................................... 87

6-1 Graphical method (Curve fitting method)..................................................... 87 6-2 Liner filter method........................................................................................... 89

6-2-1 Convenient analytical method for VES.................................................. 89 7. EXAMPLE MEASUREMENT .............................................................................. 90


Sector 6-81

1. INTRODUCTION

TYPE 3244 SPECIFIC EARTH RESISTANCE TESTER is a portable instrument which is designed to achieve measurement of the specific earth resistance quickly and accurately. This equipment was introduced by Mr. SUGINO who was employed as JICA expert of groundwater development for DGEH MOM and has been used various case of electric prospecting for groundwater development by DGEH..

2. SPECIFICATION

2-1 System

(1) Principle of measurement AC potentiometer (free of polarization, and capable of direct reading of earth

resistance).

(2) Method of power supply Transistorized low-frequency inverter. Driven by storage battery or dry batteries.

(3) Galvanometer Micro lead relay and highly sensitive taut band meter.

2-2 Specification

(1) Measuring range: 0-0.3/3/30/300Ω Scale; 0-30Ω, 0.5Ω/division

Multiplier dial ; x0.01,x0.1,x1,x10

(2) Measuring accuracy ±3% of indicated value between 10Ω and 30Ω of scale

±1% of full scale value below 10Ω of scale.

(3) Output voltage setting dial: 150/300/600V (4) Measuring current

About 200mA where one N-30 storage battery is used at 1kΩ of load resistance.

About 100mA where eight(8) SUM-1 dry batteries are used.

(5) Measuring frequency 10 - 4Hz of square wave (which may vary with magnitude of load and kind of power supply)

(6) Power supply used External power supply of DC 12V;

Eight(8) SUM-1 dry batteries (1.5V) or one NS-30 storage battery (12V, 30AH).


Sector 6-82

The former may suffice or measuring depths up to about 50m, but the latter is recommendable for greater measuring depth.

(7) Volt-ammeter: 15V (DC)/ 500mA (AC). (8) External dimensions and Weight: 247x348x211mm, 8.1kg (9) Attachment

Electrode spikes (5) and electrode spike hammer (4)

(10) Optional accessories (for 200m depth) Measuring lead wires (330m x 2set, 110m x 2 set and 5m )

3. OPERATING PRINCIPAL OF TYPE 3244

The operating principle of Type 3244 is depicted in Fig. 1. In the figure, OS denotes a trans storized oscillator and B a battery serving as the power supply for the oscillator. T1 denotes a voltage transformer, T2 a current transformer, Rv a slide rheostat, RY a synchronous rectifier, and M2 a galvanometer, respectively.

The oscillation voltage of OS is boosted by T1, causing the alternating current I (amp) to be supplied to the underground from the outer electrodes C1 and C2.

The potential difference V to be created by the earth resistance R (Ω) between the electrodes P1 and P2 is expressed as follows.

V = RI (volt)

Because of the current I, an electric current proportional to I will flow to the slide rheostat on the secondary side of T2. The potencial difference V0 occurring in the portion havig a length of L in Rv is therefore expressed as follows.

V0 = K * Rv * I * L/Lm (Volt)

(where, K is a constant of proportion and Lm denotes the maximum slideing length of the slide rheostat, when the value of resistance is Rv.) When the deflection of M2 is completely eliminated by sliding the brush so as to inverse the directions of V and V0, one obtain the bellow equations.

V = V0

RI = K * Rv * I * L/Lm


Sector 6-83

R = K * Rv * L/Lm (Ω) -------------- (4)

Thus, R can be indicated by the position of brush, L/Lm. As is apparent from the preceding formula, the indicated value has nothing to do with I and, because the electric current of M2 is O, shows the earth resistance with little reference to the earth contact resistance of C1, C2, P1 and P2. Thus, measurement can be achieved up to 10 kΩ of earth contact resistance of each electrode generally. When the electrode spike attached to this equipment is driven to a depth of about 20cm, the earth contact resistance RE of the spike will be below 10 kΩ,except where there occurs dry sand or rock/

RE = 3ρ （Ω）

(where ρ denotes the specific earth resistance in Ω-m on the ground surface)

4. CONSTRUCTION

The outside appearance of the instrument is shown in Fig.2. The function of each component is as described below.

(1) The Guard terminal (G) This guard functions to prevent the influence of possible induction within instrument.

(2) Measuring terminal This terminal serves to connect the electrode spike with the measuring lead wire.

(3) Power supply terminal This terminal serves to establish connection with the battery (12V).

(4) Volt-ammeter (M1) and volt-ampere changeover switch (S2) When S2 is set to V, M1 indicates the voltage of the battery.

When S2 is set to mA, M1 indicates measuring current I.

(5) Output changeover switch (S3) When S3 is switched to L, M and H, the secondary number of turns of T1 is changed correspondingly to cause the output voltage between the terminals, C1 and C2, to be varied to about 150, 300 and 600V respectively. Suitable range must be selected depending on the amount of earth contact resistance of the current electrode spiked.

(6) Range changeover switch (4) This switch serves to change the measuring range.


Sector 6-84

he changeover of the measuring range can be accomplished by varying the constant K of the formula (4).

(7) Push on→lock switch (S1) and pilot lamp (PL1) When S1 is depressed, the connection is established to the power supply, so that the oscillator is actuated and the PL1 is lit up. When S1 is released up, the oscillator stops and PL1 is put out. For continuation of the oscillation, the S1 must be locked by being turned to the right while in the depressed position.

(8) Galvanometer (M2) and slide rheostat (RV4) These functions are described in the preceding section.

Measuring

Volt – ampere meter Guard

Output changeover

switch (S3)

Galvanometer

Slide rheostat

(RV4)

Range changeover switch (S4) Pilot lamp

(PL1)

Push on –

Lock switch

(S1)

Power

supply

t i l

Volt-am

pere

changeo

ver

Fig.2 Outside appearance of 3244


Sector 6-85

5. OPERATING PROCEDURE

5-1 Measuring Procedure for Specific Resistance Prospecting

(1) When the point of measurement is fixed, let the symbol “G” denote that point. Then drive the electrode spikes as shown in Fig.3 and connect them with TYPE 3244 by means of measuring lead wires.

(2) Where the electrode spikes offer the earth contact resistance higher than 10kΩ wet them with water to lower the earth contact resistance.

(3) Set the volt-ampere changeover switch to V. (4) Set the output changeover switch to L. (5) Set the range changeover switch to *10. (6) Depress the push –on→lock switch. In this case, assure that pilot lamp is lit up.

(7) Assure that the power voltage is in the range of 5V ～ 13V indicated by a blue mark. If the voltage is below 5V, replace the battery.

(8) Turn and the volt–ampere changeover switch to mA. (9) Set the indication of the galvanometer accurately to “0” by adjusting the range

changeover switch and the slide rheostat. The each resistance R (Ω) is the product of the multiplicity of the range changeover switch multiplied by the indication of the slide rheostat.

(10) Calculate the specific earth resistance, ρ (Ω-m) according to the following formula. ρ = 6.28 aR a : (m)

(11) When the measuring sensitivity is more or less insufficient, set the output changeover switch to M or H, so that the measurement may be made where the measuring current (mA) is highest.


Sector 6-86

(12) When the measurement is completed, release the push-on→lock switch. In this case, assure that the pilot lamp is put off.

The steps of (3), (4), (5) and (7) require checking just once at the beginning of operation.

5-2 Measuring Procedure for Specific Resistance Logging

Resistance logging can be operated by the equipment with two or three electrode device. This item is skipped in the seminar and will be explained in the seminar for electrical logging.

5-3 Operational Note and Maintenance

(1) Operational note Max. 600V voltage is applied and approx. 200mA current is passed between the current electrodes C1 and C2. Depress the PUSH-ON button to LOCK after confirming through driving of the metal spikes into the ground. The used of rubber boots and groves is recommended for a person who will touch the metal spike.

(2) Judgment of earth condition The indication of the ammeter (mA) can be a guide to tell whether or not the earth condition of the electrode spikes is satisfactory. For the sum (100Ω – 10kΩ of earth contact resistances of C1C2, the standard indications of the ammeter are about 150 – 20mA in the case of UM-1 dry battery (fresh supply) or about 400 – 25mA in the case of NS-40 storage battery (after charging).

(3) Checking function of this instrument Set the output changeover switch to L, have all the measuring terminals short-circuited, and depress the push-on→lock switch. If the pointer of ammeter swings beyond 100mA, the oscillation circuit is functioning normally. If the voltmeter pointer stops within the blue-mark zone, the battery voltage is sufficient. Normal functioning of the measuring circuit of this instrument is ascertained by assuring that the galvanometer swings adequately when the slide rheostat is moved from 0Ω.

(4) Influence of earth current If the point of measuring happens to be selected close to power or communication system, the earth current originating from such system may possibly cause the galvanometer of this instrument to swing. If this occurs at all, suitably manipulate


Sector 6-87

the instrument so that the center of such swing will fall on the scale “0” of the galvanometer.

(5) Life of battery Under the standard use condition, the service life (total houres) of battery is as follows:

SUM-1 dry batteries About 0.5h

NS-40 storage battery About 5h

With this mind, avoid missing the time of replacement or recharging of battery.

(6) Calibration of the instrument Because of the operating principle and the construction, this instrument requires substantially no calibration. If it is found necessary for some reason, measure the standard resistance magnitude Rs in the model circuit as shown in Fig. 4.

6. ANALYTICAL PROCEDURE FOR SPECIFIC RESISTIVITY PROSPECTING (WENNER ARRAY)

6-1 Graphical method (Curve fitting method)

Plot the relation of apparent resistance ρ and electrode separation a on the semi-transparent log-log section paper, which should be equal size with “standard curve” and “auxiliary curve” (see, Fig. 6). Analysis will be described on the example curve a, b, c, d in Fig.5.

(1) Drive the curve in increasing and decreasing part respectively.

(2) Place the curve upon the standard curve, and search the most identical one to the a, b portion by trying to slide in various way (curve 1). Trace the original point 01 (ρ/ρ1 = 1, a/d1*1) on the curve under analysis. The value of a and ρ of this point 01 in scale of the curve under analysis represents specific resistivity ρ1 and depth d1 of the first layer. ρ2 can be calculated from ρ2/ρ1 of the most identical standar curve and ρ1.

(3) Place ρ1 upon the original point (ρ2’/ρ1=1, d2/d1=1) of auxiliary curve, and trace a curve which has the same value of ρ2/ρ1 as one ofρ2/ρ1 of the curve (1), (chain line II) on the curve under analysis.

(4) Again place it on the standard curve and search a curve II which in most identical to


Sector 6-88

the b, c portion sliding the original point of standard curve on the curve II. This trace it 02 gives apparent specific resistance ρ2’ of equivalent signal layer of the first layer and second layers and d2 of the second layer in unit of a and ρ. Since ρ3 /ρ2’ is, in this case, corresponding to the ρ2/ρ1of the standard curve, ρ3 can be calculated from ρ3/ρ2’ and ρ2’.

(5) Trace the curve (IV) by means of the same method as described in (3).

(6) O3 is obtained by means of the same method of (4). O3 gives ρ3’ and d3 of the third layer. Same ρ4 / ρ3’ is, in this case. Corresponding to the ρ2 / ρ1 of the standard curve, ρ4 can be calculated from ρ4 / ρ3’ and ρ3’.


Sector 6-89

6-2 Liner filter method

The graphical method has been largely replaced by computer method such as liner filter method. The liner filter method assumes an initial resistivity model, and then iterates to obtain a final resistivity image by minimizing residual between calculated and measured potential values.

Two methods are introduced in the seminar, one is Convenient analytical software for VES, another is RESIX developed by INTERPEX Co.

6-2-1 Convenient analytical method for VES

This method was developed by Mr. S. SUGIYAMA to analyzed measured data by VES using convenient computer software and now introduced in VES conducted by DGEH.

The measured data is processed on Microsoft Excel file and MS-DOS prompt with liner

filter method and shown with ρ － a curve and standard curve. The Wenner and the Schlumberger array are available for the software. The analysis procedure is (see Fig.7);

1) Selection of electrode arrangement


Sector 6-90

2) Type of measured data, resistivity (R). 3) Type assumption of resistivity layer 4) Push “Data export” button 5) Execute “go on” file on the DOS prompt window 6) Push “Read Culc. Result” button 7) Change assumption layer and repeat 2) to 6) if necessary

. Fig. 7 Convenient analytical method for VES

7. EXAMPLE MEASUREMENT

Analysis of example measurement data on OJT using above three analytical method will be conducted on the desk work of OJT.

the study on groundwater resources potential in … · and south polar regions or at the top of...

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