Presentation on theme: "GROUNDWATER RECHARGE AND FATE OF GROUNDWATER STORAGE OF"— Presentation transcript:
1 GROUNDWATER RECHARGE AND FATE OF GROUNDWATER STORAGE OF THE WEYBO RIVER CATCHMENTWELAYITA-HADIYA ZONES SOUTHERN ETHIOPIA
2 BACKGROUND Most activities come to rely on groundwater resources than on surface water resources mainly due to their sustainability and quality The Potentialities of Groundwater resource is mainly factored by the Rate of Recharge Changes in the Geo-Environment of the catchment and the entire Omo-Gibe Basin is manifested by changes in Recharge Rates
3 OBJECTIVESEstimating the Optimum Groundwater RechargeShowing the Temporal-Trend of Recharge w.r.t. the Temporal Changes of the Hydro- Meteorological ParametersAssessing the Fate of Groundwater StorageTo Show the Major Controlling Parameter of Groundwater Recharge in the Catchment
5 Elevated areas are found in the boundaries of the area PHYSIOGRAPHY 50% of the area has a slope 2-6%, 25% has 0-2%,15% has 6-12%, 6% has 12-24%Elevated areas are found in the boundaries of the areaTopographic relief ranges from m from the highest peak Damota to the lowest Weybo valley
6 GEOLOGYThe main lithologic units that are outcropped in the study area and near to its adjacent watersheds are the teritiary volcanicsThe Nazareth Groups (of Miocene to Pliocene age) and the flood basalts (Eocene to early Miocene age) are the dominant units that widely cover the study areaAbout 90% of the area is covered by the Nazareth Group, which comprises of a series of rhyolite-trachyt flows, ignimbrites, pumice and ash fallsThe Nazareth Group unconformably overlies the early flood basalts
8 HYDROGEOLOGIC UNITS AND AQUIFER SYSTEMS AQUIFER FORMATION HYDROGEOLOGYHYDROGEOLOGIC UNITS AND AQUIFER SYSTEMSAQUIFER FORMATION-Weathered and fractured ignimbrite/welded tuff-Sediments associated with weathered pumice-Weathered and fractured rhyolites and TrachytesTYPES OF AQUIFERS IN THE CATCHMENT-Dominantly leaky aquifers
10 Geological structures and hydraulic conductivity values HYDRAULIC CHARACTERISTICS Correlation has been made betweenGeological structures and hydraulic conductivity values A greater extent of the study area possessesa low permeability zone.
11 GROUND WATER FLOW SYSTEMS AND POTENTIOMETRIC CONTOURS Regional, intermediate and local flow systems
12 RECHARGE AND DISCHARGE ZONES Zonation based on topography
13 Flow lines tend to diverge from recharge areas and Zonation based on peizometric patternsFlow lines tend to diverge from recharge areas andconverge toward discharge zones
19 THE OPTIMUM GROUND WATER RECHARGE ESTIMATION BASED ON GROUNDWATER BUDGETESTIMATED GROUNDWATER OUTFLOW = 78.56GW INFLOW ESTIMATED FROM WATER BALANCE AND SEASONAL RECESSION METHOD = 81.5mmTHE OPTIMUM GROUND WATER RECHARGE = 81.5
21 FATE OF GROUNDWATER STORAGE Equating the linear equation: y = -587xGroundwater storage will be heavily affected and appreciable change in storage will be seen after 30 years now on
22 RECHARGE TREND W.R.T. CONTROLLING HYDRO-METEOROLOGICAL PARAMETERSMean precipitation is slightly decreasing,however, its rate of declination is not comparable
23 mean temperature shows an increasing trend mean wind speed shows an increasing trend
24 potential evapotranspiration is slightly increasing
25 CONCLUSION -Groundwater recharge is computed using 4 different Methods -Groundwater recharge is computed using 4 different Methodsand four different values are obtained. The optimum=81.5mm-The decline in groundwater recharge is highly attributed tochanges in the environment-Measurable changes in groundwater storage will be seen ina 30 years period of time if environmental changes arekeeping on the same rateCONCLUSIONCONCLUSION-The groundwater recharge estimated from measurements of chloride yields an over estimated result.
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