A Computer software package to estimate the unsteady groundwater flow condition using the Theis method

The graphical solution using the Theis Method for unsteady groundwater flow condition is very tedious and involves the preparation of two curves, namely the type curve and the data curve. Two approaches are used to calculate the aquifer storage characteristics, (T) the transmissibility and (Sc) the storage coefficient. Approach 1 is conducted by taking the Napier logarithm of the type curve and the data curve. The curves are then plotted on separate graphs of the same origin and normal scale. Approach 2 is conducted by plotting the type curve and the data curve on separate logarithmic papers of the same scale. A computer software procedure is proposed to accurately prepare and plot the type curve and the data curve, using the Microsoft Excel spread sheet graphical capabilities. The two curves are then copied and pasted to another powerful graphical program, Adobe Illustrator Creative Suite 5 (CS5). The type curve and the data curve are superimposed by reducing the transparency of the data curve to 50% and the match area is marked. The procedure is fast and accurate and relief the students/ designers from the burden of hand calculation and plotting. A website has been developed to provide an example of the procedure.