Aquifer Parameters, Pumping Test and the Yield

Abstract

The terms hydraulic conductivity (K), transmissibility (T) and storage coefficient (S) are useful for computation of yield. The hydraulic conductivity of an aquifer is its capacity to transmit and to yield it. The transmitting capacity for the entire thickness is known as transmissibility (T), and storage coefficient (S) of an aquifer is the volume of water discharged through unit prismatic volume. During pumping test, a time–drawdown curve is generated. From this curve, T and S values are calculated by different methods. As the drilling and pumping tests are expensive, time-taking and laborious geoelectrical measurements are used for alternate approach to estimate the aquifer characteristics. In this process, a few drillings are carried out in the area of investigation. The T and K are calculated in these boreholes with the help of pump test. Vertical electrical sounding (VES) is carried out near the boreholes. Transverse resistance (T′) and formation factors (F) are calculated from all the VES results. Then, a straight-line relation between transmissibility and transverse resistance and hydraulic conductivity and formation factor is brought out. Now, if the entire area is surveyed by VES and the T′ and F are calculated for each point, the hydraulic conductivity (K) and transmissibility (T) can be found out using the relations for the entire area of investigation. A contour can also be drawn for hydraulic conductivity and transmissibility for the area.