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

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7CHAPTER 1INTRODUCTION1.1. GENERAL INTRODUCTIONWater is a resource of critical importance for sustaining life on this planet. In Africa especially,where a greater part of the population depend on agriculture as a source of livelihood, theimperative to properly manage water resources has become even more demanding. The rapidpopulation growth and climatic changes throughout the continent in recent years have furtherhighlighted this concern.While there is a growing demand for water resources in Africa, there is limitation to currentmanagement arising from amongst others lack of sufficient knowledge about the resource. Theestimation and quantification of hydrologic parameters such as surface runoff, actualevapotranspiration and ground water recharge are key factors to the sustainable management ofwater resources. Unfortunately, parameters such as evapotranspiration or runoff are rarelymeasured directly (Nicholson et al., 1997). The few measurements that are available are at localor basin scale and out of scale with the current reality. Evapotranspiration is generally calculatedfrom empirical formulas or energy balance approaches. Runoff is usually calculated as aresidual. The problem for Africa is the general lack of data for continental scale comparisons ofwater cycle studies.With the advent of Geographic Information Systems (GIS), physical-based hydrologic modelinghas become important in contemporary hydrology for assessing these parameters as well as theimpact of human intervention and/or possible climatic change on basin hydrology and waterresources (Alemaw and Chaoka, 2003). Information gathered from these models can greatlyenhance the decision making process in these regions. Unfortunately, poor knowledge aboutthese technologies in addition to the expensive nature of some GIS software packages hasretarded progress on the Continent as a whole. However, most Governments have begundedicating many resources in acquiring these software and hardware packages for researchpurposes. This research is partly motivated by these policy changes.
81.2. OBJECTIVE OF THE RESEARCHThe specific objectives of this research are threefold:1. To estimate in quantitative terms the annual average water balance components (surfacerunoff, actual evapotranspiration, groundwater recharge, soil evaporation etc) for theentire continent of Africa using a GIS-based approach.2. To present a general overview of the variability of these components across Africa.3. To demonstrate that despite the general lack of hydrological datasets on the continentresearch on the water cycle is still possible with the few data available.
Page 5 and 6: 4LIST OF FIGURESFigure 1.1: Flowcha
Page 7: 6SUMMARYNkezeah, A.J., 2010. A GIS
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 and 40: Figure 4.5: Annual average Runoff M
Page 41 and 42: 30° 30° 10° 10° 30° 50° 30°4
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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