GEOGRAPHIC INFORMATION SYSTEM AND MODELING APPROACH FOR GROUNDWATER SYSTEMS OF RECHNA DOAB, PAKISTAN

Abstract

Excessive groundwater pumping in Rechna Doab has caused a depletion of aquifer body. Efforts were made to identify the ground flow dynamics and recharge sources of Rechna Doab. Finite difference model technique was used to study the groundwater system under steady state. Visual MODFLOW 2000 was used to steady state simulation of study area. Simulation of groundwater flow over an area of about 35,217 km2 with a uniform grid size of 2500m by 2500m was done. Study area was divided into the grid of 138 rows and 100 columns. The seepage losses from canals, horizontal flows, recharge from precipitation and irrigation return flows were put to develop conceptual model. Discharge of canals, evapotranspiration and precipitation data was collected from local government agencies. Boundary conditions, hydraulic parameters and data of 50 observation wells were applied for model calibration. The zone budget study under steady state simulation showed that the total direct recharge to the aquifer was 645.48 MCM and total drought of the aquifer was 645.49 MCM. Based on results it was concluded that model was more sensitive to hydraulic conductivity and recharge parameters.