The welenchiti area is an extensive flat plain in the north Main Ethiopian Riftrnbounded by Western highland escarpment to the north and volcanic mountainsrnto the south. It is situated between 390 14â€™ 57â€ to390 33â€™ 16â€ East and 8o27â€™ 37â€rnto 80 48â€™ 18.85â€ North covering a total area of 780 km2. The average monthlyrntemperature and the mean annual precipitation in the area are 21.1 oc and 874rnmm respectively. Potential evapotranspiration for the area was calculated usingrnPenman and Thornthwaite gives annual potential evapotranspiration value ofrn1481mm/year and 577 mm/year respectively. Actual evapotranspiration for thernarea estimated, from Turc method gives value of 697mm.While weighted actualrnevapotranspiration from soil water balance is 842mm which is almost close tornthe annual precipitation. The annual surface water out flow, estimated usingrnrunoff coefficient methods, resulted 129.5 Mm3. The overall water balance ofrnthe study area was computed with an aim of estimating the amount of annualrnrecharge to the ground water. Accordingly; annual recharge to the ground waterrnof the study area is approximated to be 8.58 Mm3. The study area isrncharacterized by deep groundwater systems encountered at an average depth ofrn170m. Their hydraulic characteristics are spatially variable, which is the resultrnof the complex nature of the lacustrine sediments and the degree of fracturingrnof the volcanic rocks. Fractured basalts, scoraceous basalts and fracturedrnignimbrites are the main aquifer units in the area. These aquifers were found tornbe good groundwater potential zones. The general trend for groundwater flowrnobserved from pieziometric heads is from northern highland toward the plain inrnthe direction of north west to south east of the study area. Groundwater type ofrnthe area evolves from Ca-Na HCO3 water type in areas close to northernrnescarpment into Na-HCO3 water type in the southern tip of the study area.