A GIS Based Water Balance Study of Africa - Physical Land Resources

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394.2.3. GROUNDWATER RECHARGERecharge is a naturally occurring process whereby permeable soil or rock allows water toreadily seep into the aquifer. This takes place intermittently during and immediately followingperiods of rain. This depends on the rate and duration of rainfall, the conditions at the upper landsurface boundary, soil moisture conditions, the water table depth and the soil type. Monitoring ofgroundwater recharge is very important because it allows for estimation of its temporalvariability and areal distribution.The estimated groundwater recharge simulated by WetSpass is presented on Fig 4.6. The valuesrun from 0-1856mm/yr with means of 34mm/yr and standard deviation 107mm. The variabilityof groundwater recharge is influenced by precipitation and runoff. The equatorial region appearsto be a high groundwater recharge area. In the drier areas, most of the little short annual rainfallcan not infiltrate to the vadose zone. Higher values are simulated for regions with lowtopography and permeable soils such as the Central and Western parts of Africa. The relief hereis gentler than in the eastern and southern parts. Normally, the recharge around the Congo basinshould have been much higher. This is certainly not the case probably because the thick tropicalrainforest sucks up much of the water that comes from precipitation and transpires it back to theatmosphere. Also, the huge forest canopy intercepts much of the rainfall from reaching the soilsurface preventing it from infiltrating into the aquifer.
30° 30° 10° 10° 30° 50° 30°40Reyear0 - 11 - 1010 - 2020 - 5050 - 200200 - 400400 - 2000No Data70°(mm)10° 10°NWE3000 0 3000 6000 MilesS10° 10°Figure 4.6: Groundwater recharge Map of Africa30° 30° 10° 10° 30° 50° 70° 30°
Page 5 and 6: 4LIST OF FIGURESFigure 1.1: Flowcha
Page 7 and 8: 6SUMMARYNkezeah, A.J., 2010. A GIS
Page 9 and 10: 81.2. OBJECTIVE OF THE RESEARCHThe
Page 11 and 12: 101.4. ORGANISATION OF THE REPORTTh
Page 15: 14independent water balances. Thus
Page 18 and 19: 17c is the vegetation coefficient [
Page 20 and 21: 19GROUNDWATER RECHARGERecharge refe
Page 22 and 23: 21CHAPTER 3MATERIALS AND METHODS3.1
Page 24 and 25: 233.3.1. TOPOGRAPHY AND SLOPEThe to
Page 26 and 27: 25textural types were dominated by
Page 29 and 30: 283.3.4 PRECIPITATION INPUT DATAThe
Page 31 and 32: 30° 30° 30° 10° 10° 30° 50°
Page 33 and 34: 32CHAPTER 4RESULTS AND DISCUSSION4.
Page 35 and 36: 30° 30° 10° 10° 30° 50° 30°3
Page 37 and 38: 30° 30° 10° 10° 30° 50° 30°3
Page 39: Figure 4.5: Annual average Runoff M
Page 43 and 44: 30° 30° 10° 10° 30° 50° 30°4
Page 45 and 46: 70°(mm)444.2.6. TRANSPIRATIONTrans
Page 47 and 48: 46areas of Cental-West Africa. The
Page 49 and 50: 48variations of these components ar
Page 51 and 52: 50CHAPTER 5CONCLUSION AND RECOMMEND
Page 53 and 54: 52REFERENCESAlemaw, B.F., and Chaok
Page 55 and 56: 54Stone, D.B., Moomaw, C.L., Davis,

A GIS Based Water Balance Study of Africa - Physical Land Resources

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