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3nd International Geological CongressFlorence, Italia, August 20-28, 2004 – http://www.32igc.org

DATA BASE DESIGN COUPLED WITH A DATA BASE DESIGN COUPLED WITH A GIS FOR WATER SUPPLY PROSPECTION GIS FOR WATER SUPPLY PROSPECTION

IN FISSURED AQUIFER MEDIAIN FISSURED AQUIFER MEDIA

Eric BOEKER Eric BOEKER 11, Mahmoud BOUZELBOUDJEN , Mahmoud BOUZELBOUDJEN 22

University of Geneva, Switzerland University of Geneva, Switzerland 11

University of Neuchâtel, SwitzerlandUniversity of Neuchâtel, Switzerland 2

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The Problem...The Problem...

“Accumulation of data is meaningless unless it is underlain by a clear definition of our goals and our definitions about how we shall use and structure that science towards an informed, decision-making process.”

(Bruce Babbit, Chairman of the federal Data Committee, 21 May 1996)

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The goals and the problematicThe goals and the problematic

1. Help in decision making: where to direct the water exploration for maximum drilling success rate?

2. Spatial, qualitative and quantitative management of water points inventories

3. Spatial, qualitative and quantitative management of the application of groundwater geophysical exploration techniques

4. Hydrogeological data management from the drilling

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5. Hydrochemical data control and interpretation

6. Test pumping data management and interpretation model

7. Finally to have a platform for retrieving questioning manipulating and formatting data to be used in other specialized interpretation or data presentation software

The goals and the problematicThe goals and the problematic

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Where are areas of highest groundwater potential ?

Where to explore for the highest drilling success rate ?

What are the pertinent parameters to be used for improving and delineating the area of groundwater exploration for high yielding boreholes ?

Creating a tool to help decision makingCreating a tool to help decision making

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Conceptual model of boreholes and available information's for

the Data Base Concept of the spatial variable distributed in 2D and 3D

=> x,y Geographic coordinates link with a (GIS) Geographical Information System

=> Z (depth in m) variable spatially distributed

x

z

y

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Organization chart Organization chart

Spatial Data base with GIS

Raster Data

Vector data

Tables and attributs

Field dataDrilling data

Water points inventory, chemistry

Cartography, geology

Interpretation

Development of tabular data base

Existing maps, analogs or digital

Topographic maps

Geology maps

Other maps

Up to date

Up to date

Model

GIS analysis

Statistic analysis

Geological model

Professional judgement

Numerisation with Arc Info

Dynamic link

Hydrogeological model and prognostic

Selection of favorable exploration zone and targets

Test pumping test

Geophysical data

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Situation of the prospected Situation of the prospected area, existing maps, or area, existing maps, or imagesimages

Planning geophysical Planning geophysical surveysurvey

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Control of Data and its Control of Data and its geographical position geographical position correctnesscorrectness

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Regionalisation of Regionalisation of variables: variables:

The BEST TARGETS FOR DRILLING

-rock conductivity,-rock conductivity, or resistivity, or resistivity,-water chemistry and so on…-water chemistry and so on…

REINTERPRETATION

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Tabular Data Base to reach the goalsTabular Data Base to reach the goals ((7 modules, >20 forms, >300 data entries possibility)7 modules, >20 forms, >300 data entries possibility)

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2

3

4

5

6

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2.1

2.2

2.3

2.4

4.1

5.1

4.2

5.2

5.3

5.4

7.1

7.2

7.3

6.1

6.2

6.3

6.4

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Query example to show Data evolution as Query example to show Data evolution as function of time…a tool for decision makingfunction of time…a tool for decision making

Number of meters drilled for Logistical queries

– Temporal evolution

Add a drilling machin in order to finisch work in time

Nomber of screen casings with diam … used since date of…each month

Lin

ea

r m

ete

rs d

rille

d p

er

mo

nth

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Query:Average weathered thickness per district and regionQuery:Average weathered thickness per district and region

Number of well bore per district and or region

Average thickness of the weathered zone per district and or region

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ApplicationApplication: Burkina Faso : Burkina Faso

Study areaStudy area: South East : South East Prospected zone > 70 000 kmProspected zone > 70 000 km2 2

> 720 boreholes integrated in > 720 boreholes integrated in the Data Basethe Data Base

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The five steps followed during our explorationThe five steps followed during our exploration

1. Defining the pertinent variables in order to answer the question: where are the zones with most groundwater potential located

2. Delineation of pertinent variables in exploration zones

3. Exploratory analysis of the pertinent variables

4. Study of the spatial distribution of the punctual measured variable: choice of the optimal interpolation method (stochastic or deterministic methods)

5. Delineation of the favourable zones for siting borehole with algebric cartography selection

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Choice of pertinent variables => Choice of pertinent variables =>

aquifer model in basement aquifer aquifer model in basement aquifer 3 selected variables :

Thickness of the weathered zone

Depth to SWL Thickness of the saturated

weathered zone

• 3 possible cases :

WL in base rock (C) WL in the fractured zone (B) WL in the weathered zone (A)

WL

WL

WL

WL WL

WL

WL

WL

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Finding the areas with: Weathered zone < 30 m Depth to WL < 10m Saturated weathered

thickness >10m

Delineation of pertinent variables for the exploration zone Delineation of pertinent variables for the exploration zone based on the pragmatic experience of Iwaco 1993based on the pragmatic experience of Iwaco 1993 (Valid for (Valid for Burkina and sub regions)Burkina and sub regions)

Combination of the 3 constraints =favourable zone for siting boreholes

Thickness of the weathered zone

(m)

De

pth

to W

L (m

)

ass

ass

MEDIUM

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1. Saturated weathered zone > 10 m

2. Weathered zone < 30 meters

3. Water level < 10 m

Favorable zones for borehole drilling (in red) according of the 3 constraints (Iwaco 1993)

Derived map @ time tDerived map @ time tii from the combinaison of 3 maps (constraint) for from the combinaison of 3 maps (constraint) for Optimization of exploration zones and boreholesOptimization of exploration zones and boreholes sitingsiting

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2

3

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Desk study

Tabular Data BaseGIS

Drilling Results data

Targeting drilling sites

Spatial data control, visualisation of queries

Geostatistic, Regionalisation of variables

• Quantitative and qualitative Management of the drilling campaign

GIS linkaerial photographs, satellite images, existing digitalised maps

Test pumping tests and water chemistry data

Geophysical field work data

(re) Interpretation of data @ time tiand data control

Water Points inventory data

ConclusionsConclusions

• Creation of Thematic maps to help decision making at different time t I

Yes or No

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ConclusionsConclusions

Questioning the Data Base (DB) with cross queries or temporal queries for drilling campaign management and reports

Iterative process for controlling data and creation of maps for water exploration and siting boreholes

Because of the dynamic link between the DB and the GIS procedures, thematic analyses on different variables can be easily executed. Once Those maps combined new maps for decision making can be derived.

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Bibliography

Barazzuoli P., Bouzelboudjen M., Cucini S., Király L., Menicori P., Salleolini M., 1999. Olocenic alluvial aquifer of the River Cornia coastal plain (southern Tuscany, Italy) : database design for groundwater management. Environmental geology 39 (2), pp.123-143, Springer-Verlag.

Böker E., 1996. Evaluation multicritères de 40 sites de la qualité d’implantation géophysique en zone de socle en prévision de forage d’eau (Niger, département de Maradi). Hydrogeology Master Thesis, University of Neuchâtel (Switzerland).

Böker E., 2003. Développement d’une base de données hydrogéologiques liée aux forages en milieu fissuré et analyse géospatiale par systèmes d’information géographique, 42p., 26 fig., Geomatic specialized certificate , University of Geneva (Switzerland).

Burrough P.A., McDonell R. A., 1998. Principles of Geographical Information Systems. Spatial Information Systems and Geostatistics. Oxford University Press, 333 p.

Bouzelboudjen M., Kimmeier F. (1998). GIS Vector and Raster Database, Advanced Geostatistics and 3-D Groundwater Flow Modelling in Strongly Heterogeneous Geologic Media : An Integrated Approach. The Eighteenth Annual Environmental Systems Research Institute Users Conference. San Diego, California, USA - 27-31 July 1998, 4p., 18 fig.

iWACO 1993. Notice explicative de la carte hydrogéologique du Burkina Faso, Ouagadougou, sept. 1993

Kimmeier F., Bouzelboudjen M., Ababou R., Ribeiro L., 2001. Travel path uncertainty : a case study combining stochastic and deterministic hydraulic models in the Rhône valley, Switzerland. 3rd International Conference on Future Groundwater Resources At Risk, Lisbon, Portugal, 9 fig., 1 ann., pp. 195-208.