lake haramaya groundwater recharge report
TRANSCRIPT
Estimation of Groundwater Recharge in the
Lake Haramaya Watershed
Tena Alamirew Agumassie
Institute of Technology
Haramaya University
December 2011
Haramaya
i
ACKNOWLEDGEMENT
We would like to acknowledge the financial support from Federal Ministry of
Water and Energy from the African Water Facility Project.
ii
Table of Contents
ACKNOWLEDGEMENTS ................................................................................................................... I
LIST OF FIGURES ............................................................................................................................. III
LIST OF TABLES ............................................................................................................................... IV
ABBREVIATIONS ............................................................................................................................... V
EXECUTIVE SUMMARY ................................................................................................................... VI
1. INTRODUCTION ........................................................................................................................ 1
1.1. General Background 1
1.2. The Problem Model and Its Significance 2
1.3. Objectives of the study 5
2. METHODOLOGY ........................................................................................................................ 6
2.1. Description of the Lake Haramaya Watershed 6
2.2. Data Collection and Analysis 9
2.2.1. Watershed Delineation 9 2.2.2. Chloride Mass Balance Method of Recharge Estimate 9 2.2.3. The Water Balance Method 10
3. RESULTS AND DISCUSSIONS ............................................................................................... 15
3.1. Rainfall Variability 15
3.2. Watershed Delineation 16
3.3. Groundwater Abstraction Estimate (2009) 27
3.4. Recharge Estimate using Water Balance Method 36
3.4.1. Change in Soil Moisture 36 3.4.2. Groundwater Discharge 38 3.4.3. Groundwater Recharge 46
3.5. Water Balance of Lake Haramaya Watershed 50
4. CONCLUSIONS AND RECOMMENDATIONS ..................................................................... 52
4.1. Conclusions 52
4.2. Recommendation 53
5. REFERENCES ............................................................................................................................ 55
iii
LIST OF FIGURES
Figure Page
1. Lake Haramaya Watershed (after Edo, 2009) ....................................................................... 7
2. Points where water level and moisture content measurement taken ............................... 13
3. Mean Monthly Rainfall of Lake Haramaya Watershed. ....................................................... 15
4. Delineated Watershed on Topo Map of the Study Area ..................................................... 17
5. Lake Haramaya Watershed Contour Map Generated (SRTM 2007) ................................... 17
6. Lake Haramaya Watershed DEM ......................................................................................... 18
7. Delineation of the Study Area from its Aerial Photo Images ............................................... 19
8. 3-D Visualization of Lake Haramaya Watershed ................................................................. 20
9. The Delineated Lake Haramaya Watershed before the Lake’s demise ............................... 21
10. The Delineated Lake Haramaya Watershed after the Lakes demise ................................. 22
11. Soil map of the study watershed ...................................................................................... 23
12. Slope map of Lake Haramaya watershed .......................................................................... 24
13. Land Use/Land cover 2000 ................................................................................................. 24
14. 1986 satellite Image of the Lake ........................................................................................ 25
15. 2000 satellite image of the Lake watershed ...................................................................... 25
16. Average Cl Concentration from sampled wells ................................................................. 34
17. Water level changes in ellas ............................................................................................... 40
18. Water ponding area of the Lake ........................................................................................ 45
19. Mass flow curve for the year 2009/2010 ........................................................................... 46
20. Daily rainfall of Lake Haramaya watershed ....................................................................... 48
21. Water table fluctuations during 2010 ................................................................................ 48
iv
LIST OF TABLES
Table Page
1. Rainfall coefficient of Lake Haramaya watershed 16
2. LULC changes for Lake Haramaya Watershed 26
3. Boreholes Owned by Haramaya University (Edo, 2009) 28
4. The Past Five Years Harar Town’s Water Supply (Edo, 2009) 29
5. Estimated Water Consumption for Agriculture 30
6. Water Consumption for People and Livestock 30
7. Precipitation chloride concentration in the 2008/09 season 31
8. Average chloride concentration of Haramaya University’s boreholes 33
9. Average chloride concentration of Harar boreholes 33
10. Average Chloride Concentration in Community’s Dug Wells 33
11. Average Groundwater Recharge 35
12. Average monthly measured soil moisture (volumetric base %) 37
13. Seasonal change in moisture for the watershed 38
14 Deep wells in the alluvial deposit 38
15. Working hours of Harari wells 39
16. Water abstraction for towns Harar, Awoday and Haramaya 39
17. Haramaya University water abstraction (Abebe, 2011) 41
18. Number of hand dug ponds "ella" and private motors in research site 42
19. Evapotranspiration loss from the watershed 44
20. Monthly surface evaporation during rainy season 45
21. Runoff generated from the watershed 47
22. Annual water balance of Lake Haramaya watershed 50
v
ABBREVIATIONS
HNRS-WSSSA Harari National Regional State Water Supply and Sanitation Service
Authority
GwBM Groundwater balance method.
CMB Chloride Mass Balance
HU Haramaya University
Mm3 Million Meter Cube
DEM Digital Elevation Model
SRTM Shuttle Radar Topography Mission
vi
EXECUTIVE SUMMARY
From 1960 up until 2004, the Harar, Haramaya and Awaday towns and its environs water
supply used to come from the dried up Lake Haramaya from 1960 to 2004. The system was
designed to serve the 70,000 population with 38 litres/day/person. Before the Lake’s demise
around 2004, the same system was serving a population of some 150,000. As a result, severe
water rationing, with many residents getting water for just a few hours every week had been a
norm.
As recently as the mid 1980s, the Lake’s maximum depth was around eight metres and it
covered 4.72 km2. The lake vanished because of converging forces of the ‘21
st century
environmental ills’: erosion and sedimentation, increased abstraction associated to population
increase, wasteful irrigation practice local government neglect and mismanagement in
enforcing lake conservation and restoration recommendations, and probably climate change.
When the lake vanished and treatment plant completely shut, with the support from the
Federal Government and international communities, the Harari Water Supply and Sewerage
Service Authority (HWSSSA) went in an all out campaign of digging boreholes into the
ephemeral lake beds, and drilled seven (2009/10) deep boreholes in the basin to provide water
to all the population which used to be supplied by the Lake. The rate of pumped abstraction
from the ephemeral lake bed was 71.2. l/s. This value is higher than the 60 l/s abstraction that
used to supply water for Harar, Haramaya and Aweday towns through the treatment plant.
Haramaya University also draws its water supply from boreholes. Reports showed that there
have been 20 boreholes of which 10 are in operation at the time of this study.
Though the dependence on this groundwater as a source of water supply is critical and
consequences of groundwater exhaustion believed to be catastrophic particularly for the
historical Harar town and Haramaya University, no worth mentioning effort has been made to
estimate the sustainable safe yield of the aquifer. If not wisely managed, the groundwater
resource of the aquifer could deplete to no recovery just as it happened to the Lake.
Unfortunately, the rate of water depletion in the aquifer cannot be visually seen. The
determination of groundwater potential and sustainable yield depends on estimation of
vii
groundwater recharge. If withdrawals exceed recharge, the water table in the aquifer will
decline. If this condition continues long enough, parts of the aquifer may be dewatered and
become unusable as a source of water. Regular and systematic monitoring of groundwater
resources is therefore of a paramount importance to all who depend on the groundwater. This
is particularly critical for the Harar town and Haramaya University.
The overarching question of this study was ‘how much is the safe/sustainable yield of the
aquifer? To answer this question, the watershed was delineated and the groundwater recharge
estimated using two methods – chloride mass balance (CMB) method and Groundwater
Balance Method (GwBM).
The CMB estimate resulted 123.4 mm/year (16.2%) of annual rainfall recharge.
Consequently, the total groundwater recharge obtained using the CMB is 6.38 Mm3. Given
that the catchment is closed, this method is expected be have underestimated the recharge.
The Groundwater Balance Method (GwBM) resulted 16.8 Mm3 (39.1% of the 828 mm 828
mm (43 Mm3), annual precipitation over the area) as recharge.
The water balance of the aquifer indicated that the discharges from the aquifer exceed the
recharge by 16.7%. This is obtained from runoff generated and direct precipitation. About
15.9 Mm3 water was lost in different ways naturally and artificially. The rest 3.7 Mm
3 water
was hold in the vadose zone. This amount is an interseasonal evaporation and cannot be
affected by human intervention. The GwBM showed a deficit of 2.8 Mm3/year. It was learned
that the amount of water balance depends on the water abstraction for irrigation which in turn
depends on the availability of water at shallower depth.
From this investigation, the first and most important recommendation is that the groundwater
system should be responsibly managed. The total amount of water falling in the watershed
could continue to provide reasonable amount of water for domestic consumption provided
that water abstraction for irrigation is ‘managed’. For this, a forum of stakeholders should be
established with immediate effect, and a binding bylaw developed. Looking into the prognosis
of rate of shrinking of the lake, both climate and population growth could not have such a
viii
drastic and sudden consequences. Irrigation water abstraction and evaporations seems to be
primary cause for the demise of the lake.
The ongoing HWSSSA’s water supply project from well fields around Dire Dawa is expected
to augment water abstractions from the ephemeral lake bed of Lake Haramaya. If it is possible
to check the irrigation water abstraction, it can even assist to revive the Lake.
Haramaya University should take a lead responsibility to mobilise aquifer recharge activities
and watershed protection. It should support more detail researcher so that the knowledge in
the aquifer system is as detail and complete as possible. It can and should provide detail
account of every drop of water falling in the catchment. Detail hydro-geological modelling
should be developed so that it will be possible to evaluate alternative scenarios. The
University should also bring all stakeholders in regular and purposeful forum.
The HWSSSA should also closely work with the University. It is dealing with a precarious
and difficult to predict with certainty resource base, and there is no time for complacency or
animosity. HWSSSA should also be in the driving seat in discussing the water issue, and
should involve in watershed development and protection activities. It is also wise of the
authority to keep on exploring alternative sources to supplement the current system.
The Haramaya Wereda Administrative authorities also need to play a pivotal role in
community mobilisation towards the watershed protection. Farmers are now ploughing the
ephemeral lake bed. This unrestrained encroaching of the wetland is expected to have an
adverse impact on the aquifer recharge.
When this three – HU, HWSSSA, Haramaya District Authorities - agree to the fact that the
Lake dried because of the combined failure or inaction, and failing to act on the proper
management of the groundwater will have a catastrophic consequence, they should organise
strong water uses committee with binding bylaw acceptable in court of law.
1
1. INTRODUCTION
1.1. General Background
Increasing population, rapid socio-economic development and urbanization, industrial
development, and intensification of irrigated production have led to freshwater shortages in
many parts of the world. Water resources of basins over the world remain almost constant
while the demand for water continues to increase because of increasing population and as a
result of economic development. In view of the increasing water demand for various
purposes and its limited availability, a greater emphasis is being laid for a planned and
optimal utilization of available water resources.
Groundwater in general is a high-value resource and is especially important as a source of
drinking water. IAH (2003) described that globally, 75 percent of drinking water supplies
come from groundwater sources, with peaks of up to 98 percent in Denmark (Stefano,
1999). In the United States, groundwater is the source of approximately 50 percent of all
drinking water, and 97 percent of that is used by the rural population (Taylor and Alley,
2001). Although in many countries, the most important use of groundwater is for drinking
water supply, in other countries or regions other uses may dominate. In Australia, for
instance, groundwater accounts for only 14 percent of domestic water use. However, it is
an important source of irrigation water and as a water supply for livestock. In India, 50
percent of the water which is used for irrigation comes from subsurface. Groundwater is
also important in maintaining the flow of rivers (known in hydrologic idiom as "base
flow") in dry periods and in contributing to the water balance of lakes and wetlands.
Groundwater abstraction has increased to complement the increasing water demand for
various purposes. Development of groundwater schemes has received considerable
attention in recent years in Ethiopia, particularly in providing drinking and irrigation water
supplies. Development efforts in Shinile zone of the Somali Regional Government and in
Central Rift Valley by Oromia Regional States are worth noting. However, in many such
instances, the expansion of groundwater development has not been preceded or
2
accompanied by systematic studies to evaluate the resource potentials of the respective
aquifers.
Increased groundwater exploitation will need appropriate knowledge of the groundwater
system, technology that suites the aquifer conditions and the water use options. The
sustainability of groundwater use is more affected by rate at which the groundwater is
pumped than the total cumulative use. Hence, quantifying recharge rates and patterns is
essential for sustainable groundwater abstraction in minimise aquifer exhaustion.
In order to derive the optimum benefit from a groundwater scheme and to keep the
resource as it is or to recover it, the primary task of recharge estimation or a proper
resource investigation is imperative. Assessing groundwater potential is generally useful to
quantifying groundwater resources within river basin districts, issuing of abstraction
licenses, assessing the groundwater contributions to rivers (base flow) and to sensitive
wetland habitats.
1.2. The Problem Model and Its Significance
Abdulaziz (2006) reported that the Harari town’s water supply used to come from the
protected “Sofi” spring. This supply became crucially inadequate due to the increasing
number of population in the town. Consequently, in 1960, a new system was developed,
based on Lake Haramaya. The system was supposed to serve the 70,000 population size
with a per capita consumption of 38 litres/pers/day. Before the lake’s demise around 2004,
the same system was serving a population of over 150,000 (including Haramaya and
Aweday Towns). As a result severe water rationing, with many residents getting water for
just a few hours every week had been a norm.
As recently as the mid-1980s, the Lake’s maximum depth was around eight metres and it
covered 4.72 km2. Since then Haramaya's water level drastically declined and completely
dried in 2004/5.
3
The lake vanished because of converging forces of the 21st century environmental ills:
erosion and sedimentation, increased abstraction associated to population increase,
wasteful irrigation practice for chat production, local government neglect and
mismanagement in enforcing lake conservation and restoration recommendations, and
probably climate change.
Increasing irrigation and domestic water use change in the local climate, and changes in the
surrounding land cover are believed to be the causes of the Lakes's demise. Agriculture
expanded dramatically starting in the mid-1970s due to improved infrastructure, increased
population, and changes in government policies toward production and marketing. Among
the crops grown is chat (Catha edulis). Catha edulis has become an exported cash crop and
pumped irrigation was economically rewarding. In addition, siltation caused by the
deforestation of the Haramaya watershed has reduced the capacity of already shallow lake.
A trend of warmer temperatures since the mid-1980s may also have increased the rate of
evaporation from the lake.
The shrinking of this already small lake had been the subject of many researchers (Tamire
1980, 1981; Heluf and Yohannes, 1997) in the past few decades though no tangible
attempts were been made to save it before it dried up completely. Solomon (2002), based
on erosion and sedimentation analysis predicted that Lake would dry up in fifteen years.
Indeed the lake did not live that long as it vanished in 2004/5. Shimelis (2003) showed that
increasing water abstraction for irrigation have resulted in the decreasing of the lake water
to the extent that it can no longer be used to supply water for domestic use to all its users.
When the lake vanished and treatment plant completely shut, with the support from the
Federal Government and international communities, the Harari Water Supply and
Sewerage Service Authority went in an all out campaign of digging boreholes into the
ephemeral lake beds, and drilled seven (by the year 2009/10) deep boreholes in the basin to
provide water to the population which used to be supplied by the Lake. Haramaya
University used also to get its water supply from boreholes. Reports showed that there have
been 20 boreholes of which 10 are in operation at the time of this study.
4
Water abstraction by the surrounding community particularly immediately after the rain
stops by digging shallow hand dug wells (illas) to irrigate chat fields and vegetables is a
common practice. This is believed to have significantly reduced aquifer recharging
capacity of the basin.
Though the dependence on this groundwater as a source of water supply is critical and
consequences of groundwater exhaustion believed to be catastrophic particularly for the
historical city of Harar and Haramaya University, no worth mentioning effort has been
made to estimate the sustainable safe yield of the aquifer. Previous works in the catchment
has been focused on the siltation (Solomon, 2002), lake water balance (Shimelis, 2003),
and surface water temporal analysis, and Groundwater Modelling of the Finkile-Adele-
Haramaya watershed (Wakgari, 2005; Abdulaziz, 2006; Geletu, 2006).
If not properly developed and managed, the groundwater resource of the watershed could
deplete to no recovery just as it happened to the lake. Unfortunately, the rate of water
depletion in aquifer cannot be seen by eyes unless scientifically monitored. The
determination of groundwater potential and sustainable yield depends on estimation of
groundwater recharge. The sustainability of groundwater use is more affected by the rate at
which the groundwater is pumped than the total cumulative use. If withdrawals exceed
recharge, the water table in the aquifer will decline. If this condition continues long
enough, parts of the aquifer may be dewatered and become unusable as a source of water.
Regular and systematic monitoring of groundwater resources is necessary for its effective
management to support the water needs of the environment and its beneficiaries. Haramaya
University believes that it should continue to air the challenges and catastrophic
consequences on the unsustainable utilisation of aquifer as it has been doing since 1980s.
The four major research questions in this study were:
What is the total catchment area contributing into the ephemeral lake bed aquifer
system?
Is there connectivity between water bodies of Finkle and Lake Haramaya?
How much is the recharge into the aquifer system?
5
How sustainable is the current abstraction?
The overarching hypothesis of the study was
The current rate of groundwater abstraction is not sustainable and will expose the
Harar town and the University to catastrophic consequences
Because of uncertainties associated in estimating aquifer yield, attempts were made to use
alternative methods through postgraduate thesis research work. In this report, the results
obtained using two methods; namely the Chloride Mass Balance (CMB), and Groundwater
Balance Method (GwBM) are presented. The third method, the water table fluctuation
method, is still ongoing.
The study will have significant practical contribution in responsibly managing the aquifer
by all parties. First and foremost, it will serve as starting point to initiate discussion among
all stakeholders. It also nudges all stakeholders to look the what if scenarios.
1.3. Objectives of the study
The main goal of this work has been to generate information on the sustainability of the
current groundwater management scenario and initiate discussion among the water
beneficiaries.
This study had the following specific objectives:
To delineate and characterise the Lake Haramaya watershed using GIS, and
To estimate groundwater recharge using water balance and chloride mass
balance methods, and
To evaluate the sustainability prevailing water management practice.
6
2. METHODOLOGY
Researchers have developed many practical methods for groundwater potential estimation
(Lernet et al, 1990, Larson, 2001, Lee, 1999; Scanlon et al, 2002, 2006; Sophocleous,
2004; Lawrence, 2006, Morville, 2007; Sandwidi 2007). However, inaccuracies observable
in hydrology due to the inherent difficulty in precisely estimating groundwater recharge
indicate that alternative methods should be used to validate the result obtained with one
method against other methods. Estimation of groundwater recharge, by whatever method,
is normally subject to large uncertainties and errors demonstrating that no single recharge
method can be assumed to be most appropriate over all scales and time periods. Geoffrey et
al., 2006 also confirms that because of the limitations and uncertainties of different
methods, the use of multiple recharge-estimation methods is beneficial and repeated work
in different time period and using different methods to reach good estimation is of
paramount importance.
With this understanding, recharge estimation using alternative methods; namely, Chloride
Mass Balance, and Water Balance methods were done by Edo (2009/10) and Abebe
(2010/11).
2.1. Description of the Lake Haramaya Watershed
Location of the Lake Haramaya Watershed
The Lake Haramaya watershed is located in the Eastern Highlands of Ethiopia, which is
administratively situated in the Haramaya Wereda of Eastern Hararghe Zone, Oromiya
National Regional State. It is found on the northern upper part of the Wabi Shebele River
Basin. It lies between 90 22' 03''- 90 27' 12'' N latitude and 410 58' 14'' - 42
0 05' 26'' E
longitude.
The watershed is situated on the main road from Addis Ababa to Harar at a distance of 500
km form Addis Ababa, and 14 km northwest of Harar town. The watershed covers almost
an area of 50 km2. It encompasses a small part of Town, the University Campus, Bate
7
town, three peasant associations (Damota, Ifa-Bate, and Tuji-Gebissa) fully, and another
two Ifa-Oromia (around 90%) and Guba-Selama (around 10%)) partially (Abdulaziz, 2006)
Figure 1. Lake Haramaya Watershed (after Edo, 2009)
Climate
The watershed experiences a nearly bimodal rainfall distribution. These are the Belg rains
(February to beginning of May) and Kiremt rains (June to September). The mean annual
rainfall has been reported to be in order of 760 mm (Edo, 2009). The elevation of the
catchment has resulted in moderate temperature; the annual mean being 180C with little
annual variation.
8
Farming System
Chat (Chata edulis) intercropped with sorghum, maize and haricot bean is the dominant
cropping system in the watershed. There is also a sizable pump irrigated vegetable
production specifically around what used to be the Lake shore.
Geology and Soils
The Hararghe Region is generally overlain limestone and sandstone deposits which began
during the Triassic period of the Mesozoic era and during the Jurassic and Cretaceious
Period of the same era (Heluf and Yohannes, 1997). According to Solomon (2002) the
highlands, including Lake Haramaya Watershed, lie over the crystalline bedrock of pre-
historic Gondwana continent, which became fractured at a much later time. The hard rocks
of the Gondwana continent (granite and genesis), which were formed the Pre-Cambrian lay
as pen plains below sea level for a longer period resulting in the deposits of very ancient
sedimentary rocks in the eastern region.
According to Tamire(1986) the Pre-Cambrian metamorphic rock, granite and to a lesser
extent genesis and mica schists, are particularly exposed on the surface throughout
Haramaya Watershed area. The steeper slopes have a large rounded boulders of granite
rocks exposed on the surface. This is a clear indication of severe erosion that has washed
away the surface soil and exposed weathering granite boulders on the land surface.
KEC (2005) identified three different types of rock the catchment area. These include the
unconsolidated sediment which cover 17 km2 of the watershed, Mesozoic (intrusive and
extrusive igneous rocks formed during Mesozoic era) and Precambrian rocks consist the
rest 33.3 km2.
9
2.2. Data Collection and Analysis
2.2.1. Watershed Delineation
Watershed delineation was first made by Edo (2009) using topographic base map (Karsa
(0941 D2) and Harar (0942 C1) prepared in 1999 from aerial photos of 1996 supported
intensive field campaign using GPS. Moreover, DEM from STRM (2007) used to verify
the delineation obtained through the physical delineation (Savant, 2002; Welhan, 2007).
Satellite image of 1986 TM and 2000 ETM were other data sets used to identify land use/
land cover of the watershed.
2.2.2. Chloride Mass Balance Method of Recharge Estimate
Rainwater samples collection
Edo (2009) collected samples using two litter capacity plastic collectors distributed all over
the watershed. Samples were collected at four different times for three consecutive days
with a total of 96 samples. The first 24 samples were collected from April 4-6, 2009, the
second May 12, 14, 15, 2009, the third June 20-22, 2009 and the fourth on July 16-17 and
19, 2009.
Groundwater samples collection
Groundwater samples were collected from five University’s and four Harar town’s active
boreholes and four active hand dug wells of Haramaya University’s surrounding
communities at four different times. The first round was collected on March 08, 2009, the
second trip was collected on May 20, 2009, the third was collected on June 13, 2009 and
the fourth was collected on July 13, 2009 from the total of 13 boreholes and hand dug
wells. The total 52 samples were collected and analyzed following the standard procedure.
The chloride concentration in the precipitation and groundwater was analyzed using
potentio-meteric selective electrode method (APHA, 1998).
10
The total deposition for a series of rainfall samples was estimated as a weighted average
using equations 2.1 (Ponce, 2006; Sangwe, 2001)
n
i
i
n
i
Pii
P
P
ClP
Cl
1
1 (2.1)
Where Clp [ML3] denotes the average chloride concentration in rainfall, i denotes a rainfall
sample, n denotes the total number of samples and Pi denotes an event rainfall (mm).
Then recharge was estimated using equation 2.2 ( Beekman and Xu, 2003; Sopholeous,
2004).
gw
p
Cl
ClPR (2.2)
Where R is the groundwater recharge flux (L T -1
); P is the average annual precipitation
(L T-1
), ClP is the average precipitation-weighted chloride concentration (M L-3
) and Clgw is
the average weighted chloride concentration in the basin groundwater (M L3).
2.3. The Water Balance Method
The methods described here are based on the works of Abebe (2010). Each of the water
balance components were computed as follows (de Varies and Simmers (2002);
Edummds(2002); Demonde et al (2010):
Recharge: the major source of groundwater recharge to the study aquifer was assumed to
be the runoff generated from the high elevated mountainous area and from precipitation on
part of the alluvial deposit covering 7.06 km2 of the whole watershed (KEC, 2005).
Runoff: There are no streams gauged in the watershed. Hence, runoff was estimated using
SCS method. Curve Numbers were calculated for the three types of soil identified in the
watershed (ERA, 2002).
11
Precipitation: The only source of water to the watershed, precipitation data, was collected
from Haramaya Meteorology Station located in the centre of the catchment. The data
collected were daily observation and converted to monthly data. The data was used mainly
to determine runoff generated in the basin as well as direct water input to the alluvial plain
(7.06 km2).
Evapotranspiration: Evapotranspiration loss from the watershed is one way of natural
water removal and it was evaluated separately to all type of crops. This was calculated
throughout the growing season of the crops growing using CROPWAT 8 model as
recommended in Allen et al (1998)
Evaporation from water surface: In rainy months during the study period, water
collected around the previous Lake area for about five months, from July to November.
This water partly escaped to the environment through evaporation and the rest join the
water table. The amount of evaporation from the water surface was estimated using
Thornthwaite method (McCabe and Markstrom, 2007) (equation 2.3)
E= (1.6(10Ta
I)6.75×10−7I3−7.71×10−5I2+1.79×10−2I+0.49)(
10
d) (2.3)
Where E is evaporation in mm/day, I is annual heat index (I=∑ i, i = (Ta
5)1.514), Ta is air
temperature (ºC) for Thornthwaite equation and d is number of days in month.
Evaporation from shallow water table: There is an area where water table is very
shallow and water from the aquifer is expected to evaporate. This was estimated using
equation 6 (Coudrain et al., 1998). The result from this equation is point estimate. Hence,
this was multiplied by shallow water table area delineated using GPS/GIS and Global
Mapper.
𝐸 = 71.9𝑍−1.49 (2.4)
Where E is the water table evaporation [mm/y] and z, the water table depth [m]; E where
the evolution of evaporation with water table depth shows that evaporation becomes
12
significant (> 10 mm/year) for shallow aquifers only (water depth < 3.7 m) (Dewandel et
al. 2010).
Water abstracted for different purpose: Water abstracted from the aquifer for different
uses – irrigation, drinking, livestock, etc were estimated through surveying with the help of
questionnaire and focus group discussions. Groundwater abstraction for agricultural
purpose (livestock and irrigation) was estimated with data collected from the Woreda.
Domestic uses estimated taking the household size and multiply with average per capita
water consumption.
Changes in soil moisture: In order to estimate moisture content of the soil throughout the
season, a profile probe was used. The Profile probe measures soil moisture content at
different depths within the soil profile. It consists of a sealed polycarbonate rod, 25 mm
diameter, with electronic sensors arranged at fixed intervals along its length.
Before starting measurement, calibration of the sensors was made at different soil type and
depth gravimetrically. The moisture content of the soil was measured for both rainy and
dry seasons at a depth of 20 cm, 40 cm, 60 cm and 100 cm. This was repeated for all five
types of soils (Cambisols, Fluvisols, Lithosols, Regosols and Vertisols) in the watershed
identified by Abdulaziz (2006).
The water storage S (m) between depths z1 and z2 ( z = z2 – z1) was computed per unit
area using equation 2.5.
𝑆 =𝜃(𝑍1)+𝜃(𝑍2)
2∆𝑧 (2.5)
Where is the water content (m3. m
-3) measured at depths z1, (m) (bottom) and z2 (m)
(top), respectively, of the layer under consideration.
The seasonal change in soil water storage S between the beginning of a dry season t1 and
the beginning of the next rainy season t2 for a layer of thickness z was evaluated using
equation 2.6.
∆𝑆 = 𝑆2 − 𝑆1 (2.6)
13
Changes in groundwater storage: Water level data of existing wells were collected using
water level sensors during the research period. Four wells were selected, and weekly
monitored. Three of the well being pumped while one had no pump and used for static
water level head monitoring. Data collected from these wells gave dynamic head. Here an
assumption of the change in groundwater storage between the beginning and end of the dry
season indicated the total quantity of water withdrawn from groundwater storage. The
change in storage (∆S) was computed using equation 2.6 (Kumars, 1987; Sami and
Hughes, 1996; Sandwidi, 2007)
∆𝑆 = ∆ℎ 𝐴 𝑆𝑦 (2.7)
Where Δh is change in water table elevation during the given time period, A is area
influenced and Sy is specific yield.
Figure 2. Points where water level and moisture content measurement taken
Data Analysis for the Water Balance Method
All water balance parameters computed with different methods was calculated with water
balance equation 2.8.
𝐼 − 𝑂 ± ∆𝑆 = 𝑅 (2.8)
14
Where, I is inflow into the aquifer in this case the run off generated from the whole
watershed and direct precipitation to the recharging area, O is out flow or abstraction of
water from the aquifer, R is recharge to the groundwater and ∆S is change in soil moisture.
The inflow into the aquifer is the sum of the precipitation and flow from the catchment.
𝐼 = 𝑃 + 𝑅𝑜𝑓𝑓 (2.9)
Where P is precipitation to the aquifer and Rof is runoff generated from the watershed.
This is with the premise that the groundwater system is completely closed system. The
outflow of groundwater from the aquifer was modelled using equation 2.10
.
𝑂 = 𝐻𝑈𝐴 + 𝐻𝐴 + (𝐼 + 𝐿)𝐴 + 𝐷𝑈𝐴 + 𝐸𝑇𝐶 + 𝐸𝑊𝑇 (2.10)
Where HUA is Haramaya University Abstraction, HA is Harari Abstraction, (I+L)A is
Irrigation and Livestock Abstraction, DUA is Domestic Use Abstraction, ETc is
evapotranspiration and EWT is Evaporation from water table.
The major source of groundwater recharge to the study aquifer is runoff generated from the
high elevated mountainous area and from precipitation on part of the alluvial deposit
covering 7.06 km2 of the whole watershed.
15
3. RESULTS AND DISCUSSIONS
In this section the rainfall of characteristics of the watershed, the catchment delineation,
recharge estimation using CMB and water table fluctuation method are presented and
discussed.
3.1. Rainfall Variability
Figure 3 shows the long term average monthly rainfall (1979-2009 (1994 missing)
distribution (Edo, 2009). The annual average rainfall was 762 mm, and the watershed
experiences a bimodal rainfall distribution with belg season peaks in April and May, and
main rainy season peak in August.
Figure 3. Mean Monthly Rainfall of Lake Haramaya Watershed.
The study watershed is characterized by four dry months and eight rainy months (Table 3).
The rainy months are from March to October. Dry months’ rainfall accounts only 7% (54
mm) of the average annual rainfall. Small rains occur in three months (March, June and
October) of the rainy seasons and the amount is 141.5 mm. Big rains occur in the
16
remaining five months (April, May, July, August and September) accounting close to 587
mm of which August giving the largest amount.
June is dry month in between two rainy months. Supplementary irrigation or in field soil
moisture conservation during this month will substantially contribute to the crop stand.
Table 1. Rainfall coefficient of Lake Haramaya watershed
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
MR 11.2 18.8 50.7 109.6 107.6 49.1 100.9 149.8 119.0 41.7 18.4 9.7
RC 0.2 0.3 0.8 1.7 1.7 0.7 1.5 2.3 1.8 0.6 0.2 0.1
MR- Mean monthly rainfall and RC- Rainfall coefficient- the ratio between the mean
monthly rainfall and one-twelfth of the annual mean.
The small rains account 18.6 % of the average annual rainfall and 24 % of the rains that
occurred in the rainy period. The big rains account 77 % of the average annual rainfall and
76 % of the rains that occurred in the rainy period.
3.2. Watershed Delineation
Topographic Map
Figure 8 shows the watershed delineated from the top map by Edo (2009). The delineated
watershed from the topo map has about 52 km2 with a perimeter of 38.40 km. The analysis
made on topographic map and GPS survey showed that more than 62% of the watershed
area lies in the altitude ranges of 2007 to 2100 m a.s.l.
17
Figure 4. Delineated Watershed on Topo Map of the Study Area
As per this watershed delineation, Haramaya and Tinike watersheds were classified under
different sub-watersheds. The maximum elevation point of the watershed was 2343 m and
the minimum elevation point from topographic map was 2035 m. (Figure 9).
Figure 5. Lake Haramaya Watershed Contour Map Generated (SRTM 2007)
The major challenge in delineating Lake Haramaya watershed was whether Lake Tinike
and Lake Haramaya are connected (Figure 5). The contour map generated from SRTM data
of 2007 supported with field observation, and discussion with local communities revealed
18
that the two sub-watersheds may or may not connect depending on the water level at Lake
Finkile. The surface runoff that originates from Gendeboy was divided into two parts.
Some of it joined Lake Haramaya Watershed and the rest joined Tinike watershed
depending on the line of divide of the watershed. The minimum elevation of Lake
Haramaya watershed is 2000 m a.s.l at the centre of the watershed. The maximum at the
line of divide for both watersheds is 2080 m a.s.l (from GPS and contour map generated
from SRTM data of 2007 (Figure 5, 6, and 7). So there is a small natural divide between
the watersheds.
The hilly and steep land in the east and northeast of the watershed covers only 8% of the
catchment area where as 71% of the catchment area was covered by undulating
topography. The remaining part is a flat land in the middle including the ephemeral lake
bed (Figure 6)
Figure 6. Lake Haramaya Watershed DEM
19
Aerial Photographs
The delineated watershed from aerial photos using mirror stereoscope is presented in
Figure 7. It was supported by 3-D visualization (Figure 8) and the streams found in the
watershed can be observed clearly after digitizing. Tip of the hills, streams flow directions,
roads and others were identified. Therefore, the line of divide of the watershed was
carefully identified and delineated which were overlaid and cross-checked with the
delineation from the topographic maps.
Figure 7. Delineation of the Study Area from its Aerial Photo Images
20
Figure 8. 3-D Visualization of Lake Haramaya Watershed
Combination Maps
Different combination maps were produced (Figure 9 and 10) by overlaying different
features (Figure 9, 10, 11, 12 and 13). A simple approximation of the Lake Haramaya
watershed boundaries (the location of the watershed divides) was generated from a map
that includes stream channels and elevations (Figure 9). Figure 9 and 10 show the
delineated watershed featuring drainage lines and Lake Haramaya. According to the results
from each delineation and overlaid at the end, the proportions of the area covering the land
feature consists 52 km2 out of which around 74% is under cultivation including chata
edulis.
21
Figure 9. The Delineated Lake Haramaya Watershed before the Lake’s demise
22
Figure 10. The Delineated Lake Haramaya Watershed after the Lakes demise
Soil and Slope Classification of the Study Watershed
Three major soils were identified as presented in Figure 11. These are chromic luvisols
covers eastern and southern central part, humicsols western and northern part and lithic
liptosols covers central part of the watershed with 35%, 33% and 32% of the total
watershed respectively. The bed of dried lake was chromic livisols and humic nitosols
(FAO, 1998).
23
Figure 11. Soil map of the study watershed
The slope map of the watershed generated from STRM 2000 DEM is shown in Figure 12.
The slope ranges from 0 – 37%, but the majority of the land mass falls in the 0-4%
category.
24
Figure 12. Slope map of Lake Haramaya watershed
Land Use/ Land Cover
The land use and land cover map of the watershed generated from 2000 Satellite Image is
shown in Figure 13. Figures 14 and 15 also show the change status of the land cover in
1986 and 2000. Both Figure 14 and 15 are exhibits how the surface water body shrank in a
space of less than 15 years.
Figure 13. Land Use/Land cover 2000
25
Figure 14. 1986 satellite Image of the Lake
Figure 15. 2000 satellite image of the Lake watershed
26
Table 2. LULC changes for Lake Haramaya Watershed
1986 2000 2009
S.No Class km2 % km
2 % km
2 %
1 Water Body 3.59 6.9 2.11 4.08 0 0
2 Marshy Area 0.52 1 1.29 2.49 0 0
3 Bare land/Settlement 11.8 23 12.3 23.8 11.57 22.39
4 Shrubs/ Cata edulis
Land
19 36 8.34 16.1 5.17 10
5 Forest Land 0.56 1.1 0.82 1.58 0.82 1.57
6 Grass Land 12.7 25 9.15 17.7 1.07 2
7 Agriculture 3.62 7 17.7 34.3 33.09 64.04
Total 51.7 51.7 51.72
From the independent image classification of the two episodic satellite imagery of 1986
TM and 2000 ETM+ (Figure 5 and 6), seven different land uses and land cover classes
(water body, marshy area, bare land/settlement, shrubs/chata edulis, forest land, grass land
and agriculture) were identified. The 1986 image classification results showed that 36.7%
was the maximum land use covered by shrubs/ Chata edulis and one percent was the
minimum land covered by marshy land as seen in Table 2. The water body (Lake
Haramaya) covered 6.9 % of the study watershed area. The classification result also shows
that 7% of the total area was covered by cultivated land excluding of chata edulis. During
the stated time, forest land covered 1.1% of the total land.
The 2000 image classification results also show that 34.3% was the maximum land use
covered by agriculture excluding of chat which was covered 16.1%. The forest land was
among the lowest with 1.6%. The water body (Lake Haramaya) covered 4.1 % of the study
watershed area as presented in Table 2. Because of afforestation in Haramaya University
27
campus, there was an increment of forest land size on satellite image of 2000, despite the
deforestation in the rest of the watershed.
The watershed was devoid of all the forest, grass and shrubs it had once; there is only shrub
land at the peaks of Gara-Damota and Eucalyptus plantation of the University’s Campus.
The consequence of deforestation is reflected on the shortage of fuel and construction
wood in the watershed.
The land use/land cover of the study also shows the maximum land covered by agriculture
64%and 1.57% was the minimum land covered by forest. According to the result, Catha
edulis shows a decreased trend from 2000 to 2009. It is classified under the same land use
with shrubs, because the spectrum reflected from shrubs and Catha edulis is similar. But, in
the actual trend, area coverage by shrubs decreased where as area coverage by Catha-edulis
increased.
3.3. Groundwater Abstraction Estimate (2009)
Haramaya University Abstraction
There were twelve boreholes in the lake watershed supplying water to Haramaya
University where ten of them were supported with submersible water pump and two of
them were not operational at the time of this research (2009). Each well has different
depths and discharge capacity (Table 3). As per the records of the University’s Technical
Service Division, groundwater is abstracted for 24 hours throughout the year with the
abstraction rate shown on Table 3. The abstracted water is used for all purpose carried out
in the University.
28
Table 3. Boreholes Owned by Haramaya University (Edo, 2009)
Well Description D(m) Q(L/S) GPS Location Status
BH-1 Workshop(Old) 25 1.2 38p0173616, 1042778 Functional
BH-2 Workshop(New) 45 1.5 38p0173621, 1042716 Functional
BH-3 Arboretum Bridge N/A 0.5 38p0175046, 1041810 Functional
BH-4 Arboretum 60 0.75 38p0174862, 1041867 Functional
BH-5 Meteorology 58 2 38p0174508, 1041851 Functional
BH-6 Rare 48 1 38p0174380, 1041877 Functional
BH-7 Farmers Training Building 52 1 38p0174158, 1041865 Functional
BH-8 Apiculture (Arab Wells) 60 2 38p0173919, 1041900 Functional
BH-9 Station (Right) 62 5 38p0173951, 1040858 Functional
BH-10 Station (left) 64 4 38p0173819, 1040877 Functional
BH-11 Vertisol Farmland N/A 2 38p0174508, 1041851 No Pump
BH-12 Apiculture 66 1.5 38p0174500, 1041921 No Pump
The maximum possible aggregated discharge was 18.95 l/s. Therefore, annual groundwater
abstraction by the University was 0.6 M m3. This amount in theory should be large enough
for the University community domestic consumption. On the other hand the University is
always seen rationing water even for student dormitories. The water management dimesion
may require a revisit.
29
Harar Town and Its Environment
According to the information from Harari National Regional State Water Supply and
Sewerage Service Authority, water discharge rate and utilization increased in the last five
years as seen in Table 4.
Table 4. The Past Five Years Harar Town’s Water Supply (Edo, 2009)
Sr. No Year (E.C) Total discharged Water (m3) Increment in m3 Increment %
1 1997 941,647
2 1998 1,171,857 230,210 24.45
3 1999 1,239,998 298,351 31.68
4 2000 1,299,641 357,994 38.02
5 2001 1,434,968 493,321 52.39
The latest (2008/9) yearly total groundwater abstraction by Harar town and its surroundings
by the investigation of this research was 1,434,968 m3. From this result, the daily water
supply of the Harar town and its surroundings for 150,000 people was around 26 l/day.
Local Communities Living in the Watershed
Edo (2009) reckoned the agricultural water abstraction to be as shown in Table 5. But his
premise grossly underestimated the amount of water abstracted for irrigation. The probable
reason might be his field sampling time was during the season where irrigation was not at
its peak as we shall see it in Section 3.5.
30
Table 5. Estimated Water Consumption for Agriculture
S.No Land Use Size in ha Water Required (m3)
1 Chat 205 518,400
2 Vegetable 121 156,816
Total 675,216
Table 6. Water Consumption for People and Livestock
S.No Water Users No of
Users
Daily Water
consumption(l/d)
Total water
Consumption (m3)
1 People 20000.00 20 146,000.00
2 Livestock 2000.00 8 5,840.00
Total 151,840.00
As presented in Table 5 the highest groundwater consumption from Lake Haramaya
watershed is for chat- edulis which covered 62.68% of the total water consumed by local
community surrounding the University. The groundwater abstracted for the purpose of
domestic consumption was only 17.65% (Table 6) of the total water abstracted by local
community.
The total groundwater abstraction from the watershed by the local community is the sum of
water for chat-edulis and vegetable irrigation and domestic and livestock use which is
estimated to be in the order of 0.87 Mm3.
The total water abstraction from the watershed by all beneficiaries is the sum of water used
by Haramaya University, Harar Town’s and surroundings and local community living in
Haramaya watershed. This is estimated to be 3.2 Mm3.
31
Chloride Content in Precipitation
The average chloride concentration measured for the rainwater from eight rainfall
collectors for four rounds is presented in Table 7.
Table 7. Precipitation chloride concentration in the 2008/09 season
The figure shows that chloride depositions over the study period from eight rainfall
collectors in four rounds for three consecutive days of rainfall. The minimum average
chloride concentration from eight rainfall collectors were 18.84 mg/l, 18.55 mg/l, 13.11
mg/l and 13.21 mg/l from first, second, third and fourth rounds, respectively. The
maximum average chloride concentration was also 21.0 mg/l, 19.4 mg/l, 18.6 mg/l and
13.8 mg/l from first, second, third and fourth rounds respectively.
S.No Round Day Average Chloride Concentration(mg/l)
1
1
1 21.04
2 2 19.42
3 3 18.84
Average 19.77
2
1 19.39
5 2 18.55
6 3 18.68
Average 18.87
7
3
1 18.60
8 2 16.11
9 3 13.11
Average 15.94
10 1 13.21
11 4 2 13.78
12 3 13.53
Average 13.84
Grand Average 17.11
32
The weighted average bulk deposition for the first, second, third and fourth rounds was
19.77 mg/l, 18.87 mg/l, 15.94 mg/l and 13.84 mg/l respectively, for eight rainfall collectors
that were distributed depending on the elevation of the watershed for three days in four
rounds. The overall average of the chloride concentration during the research was 17.11
mg/l.
Sandwidi (2007) reported the chloride concentrations ranging from 2 mg/l to 27.5 mg/l are
possible. The findings obtained in this study fall in this range and be thought safe. But
possible figures obtained from host of other researchers indicated that we rather be cautious
in using the figure reported by Edo (2009). Earlier figures include 0.5 mg/l by Larsen et al.
(2001) for western Zimbabwe, 0.28 mg/l for Bulawayo by Nyagwambo (2006); and 0.8
and 1.2 mg/l) for Mabenge by Sankwe (2001). Looking into these values, tracing possible
sources of chloride other than the rainfall might be important.
A probable reason for the difference of chloride concentration could be that the chloride
deposition depends on the part of the season when the samples are taken.
As stated by Sangwe (2001) the chloride bulk deposition shows a diminishing trend during
the course of the first showering to the last of the showering. Two reasons may be offered
for this trend. The first reason is that the early season rainfall contains dry deposition from
the dry season. Second, as stated by Makarau (1995) the rainfall between December and
April is partly due to cyclones. Such cyclones bring rain direct from the Indian Ocean and
the chances of high wet deposition are higher compared to the normal conventional rainfall
in which repeated moisture recycling plays a larger role in rainfall occurrence.
Chloride Concentration in Groundwater
The chloride concentration of Haramaya University (Table 8), Harar town (Table 9) and
community’s dug wells (Table 10) are presented hereunder.
33
Table 8. Average chloride concentration of Haramaya University’s boreholes
S.No Well Code Average chloride Concentration(mg/l)
1 W1 68.17
2 W2 70.17
3 W3 75.91
4 W4 87.98
5 W5 86.94
Average 77.83
Table 9. Average chloride concentration of Harar boreholes
S.No Well Code Average chloride Concentration(mg/l)
1 OW1 98.59
2 OW2 87.04
3 OW3 95.33
4 OW4 85.74
Average 91.68
Table 10. Average Chloride Concentration in Community’s Dug Wells
S.No Well Code Average chloride Concentration(mg/l)
1 LOW1 168.72
2 LOW2 152.92
3 LOW3 142.87
4 LOW4 136.09
Average 150.15
As seen on Table 8-10 the minimum average groundwater chloride concentration from four
different times sampling were 68.17 mg/l, 85.74 mg/l and 136.09 mg/l from University’s,
Harar Town’s and community’s boreholes, respectively. The maximum average chloride
concentration was also 87.98 mg/l, 98.59 mg/l and 168 mg/l from University’s, Harar
Town’s and community’s boreholes respectively. Thirteen wells have been used each
sampled four times with a total of fifty two samples.
34
Figure 16. Average Cl Concentration from sampled wells
The average chloride concentration measured was 77.83, 91.68 and 150.15 mg/l from
University’s, Harar Town’s and local community’s boreholes, respectively (Figure 17).
Böhlke (2002) reported that the major source of chlorides, among other chemicals, in
groundwater is agricultural fertilizer particularly potassium chloride (KCl) rather than
natural vegetation.
Böhlke (2002) also stated that cultivated areas have a higher concentration of groundwater
chloride compared to pasture and forested areas. More than 74% of Lake Haramaya
Watershed had been under cultivation where fertilizer is applied in the entire cultivated
land. Hence its potential impact in estimating capability of the chloride mass balance may
not have to be overlooked.
35
Table 11. Average Groundwater Recharge
Round Average Chloride Concentration(mg/l) Annual Recharge(mm/a) Annual Recharge (%)
RF GW
1 19.77 101.96 147.67 19.40
2 18.87 100.27 143.32 18.82
3 15.94 106.84 113.62 14.91
4 13.84 118.55 88.91 11.67
Average 17.11 106.91 123.38 16.20
The groundwater recharge has been calculated using Equation 2.6. A bulk deposition of
17.11 mg/l and groundwater chloride concentration of 106.91 mg/l has been used in the
calculations implying that the annual recharge estimate will be 123.38 mm (16.20%) of
annual rainfall (Table 12).
Consequently, the total groundwater recharge obtained using the CMB is 6.38 Mm3. From
this, the estimated abstraction is about 2.86 Mm3 which is nearly 45% of the total recharge.
As we will see in the second part of the report, the abstraction is highly underestimated.
More specifically the amount of water abstracted for irrigation and community abstraction
was noted later as very small.
36
3.4. Recharge Estimate using Water Balance Method
3.4.1. Change in Soil Moisture
Results obtained from soil moisture measurement done at different points of the watershed
was averaged on monthly basis and presented in Table 12. It is observed that soil moisture
was high in March, April, May, August, and September. Measurements done nearby
meteorological station (Fluvisols), stadium (Fluvisols) and in the woreda agricultural office
(Lithosols) of Hramaya district showed the smallest soil moisture retention. The highest
amount of moisture content were found on the alluvial deposite of the area indicated as
Arroji (Cambisols) and Ibsa (Cambisols) which are located west of the wetland. The
highest moisture content of these area resulted in generation of more runoff to the
recharging area of the unconfind aquifer. Those areas coded as Bate 1 and Bate 2 are
reported to be Regosols which is covering more than half of the watershed area (53%)
(Abdulaziz, 2006).
Soil type in the area coded as Bate 2, was found to be sandy loam textured (Abdulaziz,
2006) and the area is bare land which resulted in lower amount of change in soil moisture.
Therefore, the change in soil moisture of the upper vadose zone was found to be minimum.
This might be due to the nature of the soil and less vegetation cover in the area.
Change in soil moisture were calculated for the thickness (∆z ) of 90 cm (Table 13).
Change in soil moisture below that negelegible (Abebe, 2011). Dry season was considered
from December to March and wet season April to September and the change in soil
moisture in the two seasons was found to be 0.083 m3/m
3 while the calculated change in
moisture content was found to be 3.74 Mm3. The interpretation of this value in the whole of
the water balance is very useful in that it can not be manipulated as this is soil evaporation
driven by the sun.
37
Table 12. Average monthly measured soil moisture (volumetric base %)
B1 B2 G.B Aro Ib A.of Stad Met Stat
Dec. 37.28 28.87 31.22 40.95 37.38 30.00 23.05 25.17 42.10
Jan. 34.95 28.11 30.73 37.26 38.00 30.85 14.62 11.92 40.42
Feb. 36.43 30.68 33.85 43.08 44.00 32.24 28.59 20.92 40.23
Mar 40.64 30.36 33.83 50.87 51.58 33.75 36.77 26.75 45.38
Apr 42.73 27.58 34.42 53.69 50.56 34.33 34.31 23.38 46.22
May 44.26 28.63 35.48 58.01 52.86 33.70 35.01 25.69 52.78
Jun 27.32 28.37 28.77 40.70 33.92 26.65 20.98 19.97 32.53
July 27.13 29.43 26.60 37.85 34.22 25.83 20.47 18.02 29.57
Aug 40.68 0.00 34.31 56.97 50.59 32.43 29.34 26.62 44.08
Sep 49.75 0.00 35.67 62.28 56.08 35.65 38.37 32.58 56.70
Where
Code GPS Location Code GPS Location Code GPS Location
B1= 834870.706, 1042938.96 B2= 835604.681, 1042346.775 G.B= 833686.335, 1043347.6
Aro= 38p 0172898, 1042348 Ib= 38p 0172104, 1040466 A.of= 37p 0828663,1040538
Stad. = 38p 0174488, 1042383 Met. = 38p 0174267, 1041886 Stat= 38p 0173840, 1040878
No measurements were taken on well B2 for two months since the wells are damaged.
38
Table 13. Seasonal change in moisture for the watershed
Time B1 B2 G.B Aro Ib A.of Stad Met Stat Aver.
Dry season 0.253 0.229 0.172 0.256 0.260 0.262 0.188 0.093 0.302 0.224
Wet season 0.345 0.307 0.243 0.409 0.396 0.310 0.153 0.174 0.421 0.306
∆S(m3/m
3) 0.091 0.078 0.071 0.153 0.136 0.048 -0.035 0.082 0.119 0.083
3.4.2. Groundwater Discharge
Water abstraction for Harar, Awoday and Haramaya Towns
The rate of water abstracted by Harari National Regional State was shown in Table 14. The
combined rate of wells was 71.2 l/s. This shows that the amount of water currently
abstracted was higher than the 60 l/s abstraction while the lake was there.
Table 14 Deep wells in the alluvial deposit
Well code Discharge(l/s) Water Depth(m) GPS location Remark
1 13.5 46.5 0173288, 1041019 No generator
2 6.9 65 0173721, 1040537 With generator
4 12.3 52.3 0173624, 1041126 With generator
5 13.5 53 0173317, 1040706 No generator
6 15 39 0173400, 1042132 No generator
7 10 41 0173533, 1041629 No generator
Total 71.2 - -
Source: Personal communication with HRNS-WSSA
Estimated operating time of the wells is presented in Table 15. Since well 2 and 4 are
provided with standby generators, they are able to operate for 23 hours each.
39
Table 15. Working hours of Harari wells
Well number 1 2 4 5 6 7
Working Hour(hr) 17 23 23 15 15 16
From the above two Tables (Table 14 and 15) water abstraction for Harar, Awoday and
Haramaya towns was 1.65 Mm3/year.
The actual amount of water reached to the reservoir is presented in Table 16. The quarterly
report of HRNS-WSSA showed that 1.5 m3 water was distributed to these three towns
during the research year (2009/10).
Table 16. Water abstraction for towns Harar, Awoday and Haramaya
Quarters Water to
reservoir(m3)
Water to Haramaya
and Awoday (m3)
Water to Harar
town(m3)
loss
1st Quarter (July-Sept.) 281,000 127,000 93,000 61,000
2nd
Quarter (Oct.-
Dec.)
423,220 72,000 234,000 117,220
3rd
Quarter (Jan-Mar.) 417,277 - -
4th
Quarter (Apr.-Jun) 388,875 - -
Total (Yearly) 1,510,372
Source: Personal communication with HRNS-WSSSA
As far as loss is concerned, in the first and second quarter of the year 61,000 m3and
117,220 m3
of water was lost, respectively (which is about 21.7 % and 27.7 % of total water
distributed during the two quarters). These loses were observed during water distribution
from reservoir to stakeholders. The amount of water abstracted to these towns (Harar,
Awoday and Haramaya) was estimated to be 10.39 % of the total water abstraction from
the aquifer. The amount of water abstracted for the towns was low perhaps because during
the study period, the rainfall was fairly distributed throughout the year. Farmers have had
the opportunity to irrigate their chat throughout the year from their illa’s. Hence, the
amount of water abstracted for irrigation is relatively larger than that was pumped for
drinking water.
40
Water abstraction for Haramaya University
The estimated groundwater abstraction from this aquifer by Hramaya University is shown
in Table 17. It was found that there were 12 wells drilled in the University compound.
During the study period 2010/11, only nine of them were functional, and many of them
were operating far lower than the designed capacity. Three of them were fully abandoned.
The total amount of water abstracted from the University’s well was estimated at 0.5 Mm3.
This figure is less by 0.1 Mm3 from what was reported in Edo (2009).
Water abstraction for Irrigation and Livestock
There are tubeless wells excavated by farmers locally called “Ella”. Currently most part of
the watershed is being cultivated throughout the year for vegetable and “chat” production.
To get a better production, farmers dig more than one “Ella” per family, when the first well
gets empty, they start to pump the next (Figure 17)
A B
Figure 17. Water level changes in ellas
41
Table 17. Haramaya University water abstraction (Abebe, 2011)
Source:- Haramaya University Maintenance Division
When D (m) is well depth from surface in meter, NR is no record found, Q is discharge in liter/second and Qa is annual yield (m3/a)
Well Description D(m) Q(L/S) GPS Location Well Status Qa (m3/a)
BH-1 Around Workshop(Old) 25 1.2 0173616, 1042778 Functional 3,794.8
BH-2 Around Workshop(New) 45 1.5 0173621, 1042716 Functional 47,433.6
BH-3 Around Arboretum Bridge NR 0.5 0175046, 1041810 Functional 15,811.2
BH-4 Around Arboretum 60 0.75 0174862, 1041867 Functional 23,716.8
BH-5 Around Meteorology 58 2 0174508, 1041851 Functional 63,244.8
BH-6 Around Rare 48 1 0174380, 1041877 Functional 31,622.4
BH-7Around Farmers Training Building 52 1 0174158, 1041865 Functional 31,622.4
BH-8 Around Apiculture (Arab Wells) 60 2 0173919, 1041900 Disfunctioning 0
BH-9 Around Station (Right) 62 5 0173951, 1040858 Functional 158,112.0
BH-10 Around Station 64 4 0173819, 1040877 Functional 126,489.6
BH-11AroundVertisol Farmland NR 2 0174508, 1041851 No Pump 0
BH-12 Around Apiculture 66 1.5 0174500, 1041921 No Pump 0
Total 501,848
42
Ella is the principal source of water for irrigation and livestock production for local farmers.
Table 18 shows the number of Ellas in each Kebele in the watershed. There are about 15050
Ellas (Wereda water resource office, Personal communication 2009). Result obtained from
development agent and district experts shows the number of motor pumps in Damota kebele
were the highest. From the total 15050 Ellas in the Wereda, 804 are found in the watershed.
Table 18. Number of hand dug ponds "ella" and private motors in research site
No Name of kebele Number of Ella Number of motor pump
1 Tuji gebisa 500 143
2 Efa Bate 20 31
3 Damota 456 257
4 Finkile 512 287
5 Efa Oromia 316 118
Total 1,804 836
Source:- HWRO (personal communication)
Estimated water abstraction was done based on well surveys and estimated pumping hours.
The farmers used water from “Ella” to irrigate crops using small private motor pump with
discharge of 3 l/s to 7 l/s. Pumps purchased by farmers in the area are 3 to 4 l/s capacity
range.
About 1500 farmers were using pump in the watershed. More than 836 pumps were found
with an average discharge rate of 4 l/s with average pumping hours of 5 hr/day. The
estimated total abstraction rate for irrigation was 3.3 m3/s, daily abstraction of 28208 m
3/day.
Irrigation practice in the surrounding area usually occurred twice per annum. The first started
in November and ends in last February; the next irrigation occurred from mid April to mid
June. The estimated amount of water abstracted for both irrigation and livestock waters was
5.1 Mm3.
43
Water abstraction for Bate and Gende Je’e
Two deep wells that provide water for Bate and Gende Je’e villages abstract water at a rate of
100 m3/ day and 37.8 m
3/day respectively. The annual discharge from the two were 50434
m3/a.
Water abstraction for domestic use
There are more than 15 hand pumps installed but during the study period 10 werefunctional.
About 1355 households are dependent on the aquifer for domestic purpose. On average, the
size of the community was estimated to be six, making the number of people living in the
community to be 8,130. The average per capita consumption of developing country was
estimated to be 5 - 15 l/day/ person (Streeter and Portland, 2009). The estimation done after
oral discussion made with farmers also shows that it is in between 6 to 10 l/day/person.
Hence, the amount of water abstracted from the shallow wells for domestic consumption was
estimated with an average rate of 8 l/day/ person, and the abstraction found to be in the order
of 23,805 m3/a.
Evaporation from water table
During data collection, it was found that the water table in the area ranged between 0.4 m and
6 m in dry season. In the study time, the wet land in the well field was estimated to be 1.92
and 0.245 km2 (Figure 18). The estimated amount of water evaporated from water table was
85076 m3/a.
The wet land area on Figure 18 shows the shape of shallow water table area in the watershed.
The area exposed for shallow water table was 2.2 km2. The total water evaporated from the
water table was 39.3 mm or 85084 m3/a.
44
Evapotranspiration
Table 19 shows water lost or consumptively used by crops grown in the area is reckoned to
be as shown in Table 20.
Table 19. Evapotranspiration loss from the watershed
Land Use area coverage (ha) AET(mm/a) ET* 10(m3)
Chat
Annual
base
338 997.19 337049.3
Eucalyptus 82 1376.35 112860.7
Grass 107 1529.28 163633.0
Total (TEL) 613,543.00
Small vegetable for
growing
period
183 382.00 69906.0
Maize 234 326.02 76287.5
Sorghum 215 412.77 88745.6
Total (TEL) 234,939.10
AET = Annual evapotranspiration
TEL = Total evapotranspiration loss
ET = Evapotranspiration
Higher value in evapotranspiration loss was estimated from chat fields. As the area coverage
for chat is more than the rest plant. However, the estimated evapotranspiration loss rate of
grass was very high. Evapotranspiration from the first three plantations were calculated for
the whole year as they are categorized through permanent crop group. For the rest, it was
considered only their growing season and which makes the value for these crops less.
From the whole watersheds, evapotranspiration loss was 8.48 Mm3. The dominant losses
were 39.7 % for chat, 19.3 % for grass and 13.3 % for eucalyptus plantation.
Evaporation from surface water
The estimated monthly direct evaporation from water surface is shown in Table 18. The
results showed a value of as low as 1.82 mm in November to a high as of 3.33 mm in
September.
45
Table 20. Monthly surface evaporation during rainy season
Months July August September October November Total
Evaporation (mm) 3.26 3.27 3.33 2.49 1.82 14.17
The evaporation loss from surface of water body was estimated for five months when water
accumulates on part of the previous Lake site. The total amount of water evaporated was
found to be 14.17 mm.
Figure 18. Water ponding area of the Lake
Figure 18 shows the area where flood accumulated in rainy seasons in the upper area which
was estimated to be 1.87 km2. Water evaporating from this area in rainy season was found to
be 26 thousand cubic meter per year.
46
3.4.3. Groundwater Recharge
Inflow to the aquifer was summed up from direct precipitation to the aquifer recharging area
and runoff generated from the catchment. It is important to note that the groundwater is
assumed to be a closed aquifer with no connectivity to the neighbouring Finlele and Adele
aquifers.
Runoff generated by the catchment
The runoff generated estimated using US-SCS CN method is presented in Table 21, and
Figure 19 shows the mass flow curve estimated using the Model.
Figure 19. Mass flow curve for the year 2009/2010
The amount of flood observed in the result indicated that April, July and October gave 45.7
mm, 52.84 mm and 59.4 mm, respectively. March, April and the beginning of May are
known as belg rains while June to September are known as kiremt rain. Field observation
made during data collection time showed that these pick runoff build up ponding on the
empheral lake bed. The values of flood in some months were zero, i.e no occurance of flood
in months like December, February and June.
0
50
100
150
200
250
300
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Ru
no
ff f
rom
wat
ers
he
d in
mm
Months
Cumulative runoff
47
Table 21. Runoff generated from the watershed
S.No Months Flood in mm Area(km2) Flood in m
3
1 September 6.42342 44.94 288,668.375
2 October 59.3983 44.94 2,669,361.285
3 November 0 44.94 0.000
4 December 3.24724 44.94 145,930.969
5 January 0 44.94 0.000
6 February 1.70614 44.94 76,673.879
7 March 27.3082 44.94 1,227,230.732
8 April 45.71 44.94 2,054,212.928
9 May 7.25 44.94 325,871.572
10 June 0 44.94 0.000
11 July 52.81 44.94 2,373,395.319
12 August 40.567 44.94 1,823,101.298
Total 244.4203 10,984,446.356
The annual runoff generated during the 2009/10 year was higher than the average value
reported in Solomon et al. (2006) which was about 6.73 M m3/year. The estimated runoff
during this research time was 10.98 Mm3/year
Precipitation
Annual precipitation for the year 2009/10 was 828 mm. The value was more than the average
annual rainfall (761.6 mm) calculated for previous 30 years by Edo (2009) and annual rainfall
value of 751 mm reported in Tamiru, et.al (2006). For study year, a minimum rainfall value
of 2.70 mm in January and a maximum rainfall of 144.9 mm in July were recorded. Figure 20
shows the real time(2009/10) temporal rainfall distribution. Compared to the historical
records, the year was one of the wettest year (Abebe, 2010) with well spread temporal
distribution.
48
Figure 20. Daily rainfall of Lake Haramaya watershed
Groundwater Level of the Well Field Area of the Catchment
The results of water table depth fluctuation monitored during the study period is shown in
Figure 21.
Figure 21. Water table fluctuations during 2010
0
10
20
30
40
50
60
70
11
12
13
14
15
16
17
18
19
11
01
11
11
21
13
11
41
15
11
61
17
11
81
19
12
01
21
12
21
23
12
41
25
12
61
27
12
81
29
13
01
31
13
21
33
13
41
dep
th i
n m
m
day
10
12
14
16
18
20
22
24
11
-Fe
b
03
-Mar
23
-Mar
12
-Ap
r
02
-May
22
-May
11
-Ju
n
01
-Ju
l
21
-Ju
l
10
-Au
g
30
-Au
g
Wat
er
tab
le d
ep
th(m
)
Observation date
Well3
Well1
Well2
49
Figure 21 shows the value of water table observed from three observation wells starting from
mid of dry season(Feburuary) to mid of rainy season (August). The two wells (Well 1 and 2)
were functional and gave the dynamic water level. The third (Well 3) was not operational
hence the had no pump and it gave static water level. The value from well 3 was used to
estimate change in groundwater level. The result from this well showed that the change in
groundwater table was about only 1 m.
Change in groundwater storage for the alluvial deposit area was calculated from water table
data. The estimated specific yield for the study area ranges 10% -16% (Abebe 2010). The
average specific yield for the area was found to be 11% (KEC, 2005 and GWREM, 1997).
From measurement done the change in groundwater storage was found to be 1.8 Mm3 in the
research time from an aquifer area of 17 km2. This value is from one well and one season
sideline observation and should be used to make any conclusion. The value obtained here
need to be substantiated by recalculating the total aquifer area through a detail hydro-
geological survey. It is expected that the study using the water table fluctuation method could
substantiate this investigation using detail hydro-geological studies.
50
3.5. Water Balance of Lake Haramaya Watershed
After estimating all the necessary parameters water balance of the area was calculated. This
was done by adding inflows and subtracting it from the aggregated outflow from the
catchment. The water balance calculated using equation 2.7, 2.8 and 2.9 resulted in values
obtained in Table 11.
Table 22. Annual water balance of Lake Haramaya watershed
Parameters Estimation in m3 In M m
3
Precipitation (direct) 5,845,680 Inflow m3 16.8
Runoff 10,984,446.36
Surface Evaporation 26,494.65
Outflow m3
15.9
Evapotranspiration 8,484,820.60
Water table Evaporation 85,084
Domestic Use 23,805
Gende Je 13,834.80
Bate Town 36,600
Irrigation and Livestock 5,076,960
Haramaya University 501,848
Harari Wells 1,654,933
∆S 3,736,494 ∆S 3.7
R -2.8
In the table above inflow represents all water added to the aquifer (recharge) while outflow
represents water abstracted or taken from the aquifer naturally and artificially. ∆S is the
change in soil moisture for two seasons in vadose zone.
From the total water balance, the aquifer recharge was estimated to be in the order of 39 %
(16.8 Mm3/yr or 324 mm/yr) of the total precipitation over the area 828 mm/yr 43 Mm
3.
The water balance of the aquifer indicated that the discharges from the aquifer exceed the
recharge by 16.7%. About 15.9 Mm3 water was lost in different ways naturally and
artificially. The rest 3.7Mm3 water was hold in the vadose zone.
51
Tamru et. al (2006) reported that contradicts the finding of this author. They have found that
the water abstraction was 316% higher than effective precipitation. Our study and actual
observation on the resilience of the system demonstrated this to be an overreaction. Further
KEC (2005) reckoned that abstraction was 100% higher than the recharge.
The reason why the different values could not be reconciled clearly shows challenge in
estimating groundwater.
52
4. CONCLUSIONS AND RECOMMENDATIONS
4.1. Conclusions
The knowledge of the safe/sustainable groundwater yield could save both Harar town,
Haramaya University and surrounding communities from catastrophes. The saw lake
vanished, we failed to decisively act. We will not see when the groundwater system vanishes
until the consequence is too painful to bear.
The knowledge of contributing catchment is very important in calculating the water budget
precisely. Abebe (2010) estimated the area to be 50 km2 while Edo(2009) estimated it to be
52 km2. The deference is on agreeing the Fikle-Haramaya divide. An average value for
practical purpose could be conservative enough.
Two methods of groundwater recharge estimation were used to reckon the groundwater
recharge in the ephemeral lake beds of Lake Haramaya. The average recharge using the
chloride mass balance technique was 16% or 123.4 mm/yr; from this, the total recharge
volume was 6.4 Mm3. Given the fact that catchment is closed, the estimated rate of recharge
may be too small.
Using water balance method, from the total volume of 43 Mm3/year rainfall, the total
recharge to the groundwater was 16.8 Mm3/year. The amount of water abstracted via
different avenue was 15.9 Mm3/year. Much of the water is lost through evaporation (8.5
Mm3/year), irrigation (5 Mm
3/year), and Harari town water supply (1.7 Mm
3/year). The
amount of water stored in the soil profile was 3.7 Mm3/year. Based on this study, there is 2.8
Mm3/year deficits.
The rate of pumped abstraction from the ephemeral lake bed was 71.2. l/s. This value is
higher than the 60 l/s abstraction that used to supply water Harar, Haramaya and Aweday
towns.
Looking into the 2009 and 2010 studies, given the backdrop of the uncertainties in recharge
estimation groundwater sustainability, the amount of water abstraction is not sustainable. The
system is no more resilient.
53
Abstraction for irrigation depends on the presence of shallow water table. Farmers continue
to pump as long as water is at the pumping depth. Abstraction for irrigation decreases with
the depth of water table.
4.2. Recommendation
The first and most important recommendation is that the groundwater system should be
responsibly managed. The total amount of water falling in the watershed could continue to
provide reasonable amount of water for domestic consumption for all the communities
provided that water abstraction for irrigation is effectively managed.
Reflecting on the rate shrinking rate of the former lake, both climate change and population
increase could not be the most immediate driver. Water abstraction for irrigation seems to be
primary cause for the demise of the lake. Hence, it is therefore imperative that integrated
water management is important.
The ongoing Harari HWSSSA water supply project from Dire Dawa well fields is expected to
augment abstractions from the ephemeral lake bed. If it is possible to check the irrigation
water abstraction, it can even assist to revive the Lake. But this will remain a daunting
challenge. The chat market incentives, ease of access to irrigation pumps, and exposure of the
Woreda farmers will remain a serious challenge to enforce this policy recommendation.
There are a number assumptions made in estimating the recharge. Many of them require
detail hydro-geological study. The findings of the MSc students drew the attention of PhD
hydro-geologist researchers. This is expected to take us even closer. All equipment, material
and financial support by the Harari regional government, Haramaya University, and Ministry
of Water Resources should be provided.
June in the middle two months is dry. Many crops suffer due to paucity of moisture during
this time. Farmers could be encouraged to practice either in-situ moisture conservation.
The major stakeholders who should be in the forefront are Haramaya University, Harari
Regional Government, and Haramaya Woreda authorities. Those who pity the demise of the
54
lake blame the University for taking low profile to the incidence. But there is little that the
University could have done unless all stakeholders discuss and act together.
Haramaya University should take a lead role in artificially recharging the aquifer system.
Harari National Regional state should also contribute financially and materially towards this
end.
There is plenty of room to reduce the conveyance loss. Both Haramaya University and Harari
National Regional state have plenty do in this respect.
Finally the formation of an institution or water user board – must be the immediate task. The
Board in consultation with the community must establish bylaws enforceable in the court of
law.
55
5. REFERENCES
Abebe Mengistie, 2011. Groundwater recharge estimation for Lake Haramaya watershed
using groundwater balance approach. MSc thesis, Haramaya University, Ethiopia.
Abdulaziz Mohammed, 2006. Optimum groundwater utilization and management in Lake
Haramaya Watershed. MSc Thesis, Mekelle University. Ethiopia.
Allen, R.G., L.S. Pereira, D. Raes and M. Smith 1998. Crop evapotranspiration: guidelines
for computing crop water requirements. Irrigation and Drainage Paper n.56. FAO,
Rome, Italy, 300 pp
APHA, 1998. Standard method for examination of water and wastewater, 20th edition,
Washington DC, USA.
Beekman, H.E. and Y. Xu, 2003. Review of groundwater recharge estimation in arid and
semi-arid southern Africa. In: Xu Y and Beekman HE (eds) Groundwater Recharge
Estimation in Southern Africa. UNESCO IHP Series No. 64, UNESCO Paris, 3-18.
Böhlke, J-K, 2002. Groundwater recharge and agricultural contamination. Hydrogeol J.
10:153-179.
Bromley, J., W.M. Edmunds, E. Fellman, J. Brouwer, S.R. Gaze, J. Sudlow and J.D. Taupin,
1997. Estimation of rainfall inputs and direct recharge to the deep unsaturated zone of
southern Niger using the chloride profile method. Journal of Hydrology. 139-154.
Coudrain-Ribstein, A., B. Pratx, A. Talbi, and C. Jusserand, 1998. Is the evaporation from
phreatic aquifers in arid zones independent of the soil characteristics? Paris, C. R.
Acad. Sci. 326: 159-165.
De Vries, J.J. and I. Simmers, 2002. Groundwater recharge: an overview of processes and
challenges. Hydrogeol. J. 10: 1: 5-17.
Dewandel, B, Perrin, J., Ahmed, S. Aulong1, S., Hrkal, Z., Lachassagne1, P. Samad and M.
Massuel, S., 2010. Development of a tool for managing groundwater resources in semi-
arid. hard rock regions. Application to a rural watershed in south India.
EAH (Ethiopian Association of Hydrogeologists), 2007. Abstracts of the first Annual
Congress, Ghion Hotel, Addis Ababa, Ethiopia.
Edmunds, W.M. and S. C. Tyler, 2002. Unsaturated zones as archives of past climates:
toward a new proxy for continental regions. Hydrogeology Journal 10: 216-228.
Edo Baresa, 2009. Lake Haramaya Watershed Delination and Groundwater Recharge
Estimation Using Chloride Mass Balance Method. An MSc.Thesis, Haramaya
University, Ethiopia.
ERA (Ethiopian Roads Authority), 2002. Drainage Design Manual, Addis Ababa, Ethiopia.
56
Geletu Belay, 2006. Numerical Groundwater flow modeling of the Adelle – Haromaya dry
Lakes Catchment (East Hararghe, Oromia Regional State). An MSc. Thesis, Addis
Ababa University.
Geoffrey, N. and W. Dennis, 2007. Ground-Water Recharge in Humid Areas of the United
States--A Summary of Ground-Water Resources Program Studies. U. S. Geological
Survey Ground-Water Resources Program 411 National Center Reston, VA 20192.
Gieske, A.S.M., 1992. Dynamics of groundwater recharge: a case study in semi-arid eastern
Botswana. PhD Dessertation, Vrije Universiteit, Amsterdam, The Netherlands.
Grismer, M.E., S. Bachman and T. Powers, 2000. A comparison of groundwater recharge
estimation methods in a semi-arid, coastal avocado and citrus orchard (Ventura County,
California). Hydrol. Process. 14:2527-2543.
GWREM (Groundwater Resource Estimation Methodology), 1997. Report of the
Groundwater Resource Estimation Committee, Ministry of Water Resources,
Government of India, New Delhi.
Heluf Gebrekidan and Yohannes Ulloro, 1997. Soil and water conservation studies on soils
of Hararge highlands, Eastern Ethiopia, Haramaya University, Haramaya.
Karamara Engineering Consultancy (KEC), 2005. The Study of Groundwater Modeling at
Lake Alemaya Basin. Addis Ababa, Ethiopia.
Kumar, C. P. and Seethapathi, P.V., 1987. Assessment of Natural Groundwater Recharge in
Upper Ganga Canal Command Area, Part I - Groundwater Balance. National Institute
of Hydrology.
Kumar, C. P., 1987. Estimation of Natural Groundwater Recharge. ISH J. Hydraulic
Engineering, 3,1,61-74.
Larsen, F., R. Owen, T. Dahlin and P. Mangeya, 2001. A preliminary analysis of the
groundwater recharge to the Karoo formations, mid-Zambezi basin, Zimbabwe. 2nd
WARFSA Symposium: IWRM: Theory, Practice Cases; Cape Town, 30-31 Oct. 2001.
Lawrence, N., 2006. Groundwater Recharge Estimation and Water Resources Assessment in
a Tropical Crystalline Basement Aquifer. PhD Dissertation, Delft University of
Technology and of the Academic Board of the UNESCO-IHE Institute, the
Netherlands.
Lee, M., 1999. Surface hydrology and land use as secondary indicators of groundwater
recharge and vulnerability. An MSc thesis, Trinity College Dublin.
Lerner, D. A., A. S. Issar and I. Simmers, 1990. Groundwater Recharge. A guide to
understanding and estimating natural recharge. International Contributions to
Hydrogeology, Verlag Heinz Heise, Vol. 8: 245 pp.
McCabe, G.J. and S.L. Markstrom, 2007. A monthly water-balance model driven by a
graphical user interface: U.S. Geological Survey Open-File report 2007-1088, 6 p.
57
McCord, J.T., C.A., Gotway and S.H. Conrad, 1997. Impact of geologic heterogeneity on
recharge estimation using environmental tracers: Numerical modeling investigation.
Wat. Resour. Res. 33: 6: 1229-1240.
Morville, T. S. 2006. Groundwater Recharge and Capillary Rise in a Clayey Till Catchment
Ph.D. Thesis. Environment and Resources; Technical University of Denmark
Copenhagen, Denmark.
Ponce, V. M. 2006. Groundwater Utilization and Sustainability. Journal of Hydrologic
Engineering, http://groundwater.sdsu.edu/victor_ponce.php
Sami, K. and D.A. Hughes, 1996. A comparison of recharge estimates to a fractured
sedimentary aquifer in South Africa from a chloride mass balance and an integrated
surface-subsurface model. J Hydrol 124: 229-241.
Sandwidi, W. J-P., 2007, Groundwater potential to supply population demand within the
Kompienga Dam Basin in Burkina Faso. PhD. Dissertation, Bonn University,
Germany.
Sangwe, K. M., 2001. Recharge map of Zimbabwe and validation of rain gauges for country
wide total atmospheric chloride deposition studies. MSc WREM Thesis, Dept. of Civil
Engineering, Uni. of Zimbabwe. Harare, Zimbabwe.
Savant, G., L. Wang and D. Truax, 2002. Remote sensing and geospatial applications for
watershed delineation. Mississippi State University, Mississippi. USA.
Scanlon, B. R., R. W. Healy, and , P. G. Cook, 2002. Choosing appropriate techniques for
quantifying groundwater recharge. J. Hy.10:18-39.
Scanlon, B.R., K.E., Keese, A.L., Flint, L.E., Flint, C.B., Gaye, W.M., Edmunds and I.
Simmers, 2006. Global synthesis of groundwater recharge in semiarid and arid regions.
Hydro. Process. 20: 3335-3370. Wiley InterScience, UK.
Scanlon, B.R., R.W. Healy and P.G. Cook, 2002. Choosing appropriate techniques for
quantifying groundwater recharge. Hydrogeology Journal. 10: 18-39.
Scanlon, B.R., S.W. Tyler, and P.J. Wierenga, 1997. Hydrologic issues in arid, unsaturated
systems and implications for contaminant transport. Reviews of Geophysics, 35, 461-
490.
Shemelis Gebriye., 2003. Performance evaluation of small scale irrigation practices in Lake
Haramaya watershed and methods of improving water application efficiency. MSc
Thesis, Haramaya University.
Solomon Muleta, 2002. Soil erosion and sedimentation analysis of Lake Alemaya Catchment.
MSc thesis, Alemaya University. Ethiopia.
Solomon Multa, Yohannes F. and Rashid M., 2006. Soil Erosion Assessment of Lake
Alemaya Catchment, Ethiopia. Published online in Wiley InterScience
(www.interscience.wiley.com). DOI: 10.1002/ldr.713.
58
Sophocleous, M., 2004. Groundwater Recharge. Encyclopedia of Life Support Systems
(EOLSS), Developed under the Auspices of the UNESCO, Eolss Publishers,
Oxford,UK, [http://www.eolss.net].
Streeter, A. K. and O. Portland, 2009. We Use How Much Water? Scary Water Footprints,
Country by Country. Science and Technology (water).
Sun, X., 2005. A water balance approach to groundwater recharge estimation in Montagu
Area of The Western Klein Karoo. MSc Thesis, University of the Western Cape,
Bellville, South Africa.
Tamirie Hawando, 1980. Agro-ecological impacts on Soil fertility status and utilization of
agricultural lands in Hararge highlands, Eastern Ethiopia, AAU, College of Agriculture,
and Haramaya.
Tamirie Hawando, 1981. The role of improved soil, water and crop management practices in
increasing agricultural production in Ethiopia, AUA, Haramaya.
Tamiru A., F. Wagari and L. Dagnachew, 2006. Impact of water overexploitation on highland
lakes of eastern Ethiopia. Environ Geol 52:147–154.
Taylor, C. J. and , M. Alley, 2001. Ground-Water-Level Monitoring and the Importance of
Long-Term Water-Level Data U.S. Geological Survey Circular 1217 Colorado 2001.
Wahi, A.K., 2005. Quantifying mountain system recharge in the upper san pedro basin,
Arizona, using geochemical tracers. MSc Thesis. Arizona University, USA.
Wakgari Furi, 2005. Groundwater productivity and the hydrology of the dry lakes basin in the
north central sector of east Hararghe zone. An MSc. thesis, Addis Ababa University
Welhan. J, 2007. Watershed delineation procedures. Idaho Dept. of Water Resources. Idaho,
USA