SIMULATION OF TRANSIENT GROUNDWATER FLOW IN A WELL PENETRATING CONFINED AQUIFER IN SOUTHERN ROHRI COMMAND

A transient groundwater flow model is developed in the framework of FEM with standard Galerkin approach. The simulation model is applied to a real field problem comprising an area containing homogeneous, anisotropic type confined aquifer located over 75.69 km2 horizontal impervious layer in Southern Rohri command, at Tando Allahyar district of Sindh province Pakistan. The area is discritized into triangular elements of non-uniform sizes. The confined aquifer contains a sink with radial flow to the well that fully penetrates the aquifer. The model is run for 10 time steps to simulate the transient conditions. The radius of influence of the well after continuous pumping of 88 hours maximally goes up to 900 m. Performance of the model is tested at 4 nodes. The mean residual (i.e. the difference between the predicted and the observed values of piezometric heads) at these nodes on all the 10 time steps varies between 1.44  10-4 and 6.61  10-4 m. Performance of the model is measured by statistical parameters; ME varies between 0.0060819 and 0.0000014; RMSE varies between 0.009098 and 0.0000258; and Efficiency of the model is evaluated as 99.9 %.