GROUND WATER FLOW AND WATER BUDGET FOR THARTHAR LAKE

Groundwater inflow to Tharthar lake and leakage from it, in time and space, were evaluated using hydrologic data and simulation model (Processing Modflow Pro) of the groundwater system adjacent to the lake. The temporal parameters include the time unit, stress period, time steps, and transport steps. The spatial parameters include the initial hydraulic head, horizontal and vertical hydraulic conductivities, and effective porosity. The simulation model indicates that groundwater inflow to the lake and leakage from the lake to the groundwater system are the dominant components in the total inflow (precipitation, surface water inflow, and groundwater inflow) and total outflow (evaporation, surface water outflow, and leakage) budgets of Tharthar lake. Simulated groundwater inflow and leakage were approximately (5 ) and (10 ) times larger than precipitation plus surface water inflow to the lake and evaporative losses plus surface water outflow respectively, during the years 1992-1996. The exchange of water between Tharthar lake and the groundwater system was larger than the atmospheric lake exchange. A consistent pattern of groundwater inflow was also evident throughout the study period. The residence time for groundwater discharged at Tharthar lake was estimated to be within a range of (4 ) to (11 ) years. Flow-path evaluations indicated that the Lower Fars formation probably has negligible influence on the groundwater inflow to Tharthar lake. The water budget and flow-path evaluation provide critical information for developing the budgets for Tharthar lake ...