Parameterization of Groundwater Aquifer System

Abstract

In order to assess groundwater potential in any area, and/or to evaluate the impact of pumpage on the groundwater regime, it is essential to know the aquifer parameters. These are chiefly Transmissivity (T) and Storativity (S). These parameters are also vital for the management of the groundwater resources through the use of groundwater flow model. These parameters are estimated either by means of in-situ test or performing test on aquifer samples brought in the laboratory. The applicability of the result from the laboratory test has limitations while in-situ tests give representative aquifer parameters. The most common in-situ test is pumping test performed on wells, which involves the measurement of the fall and rise of water level with respect to time. The change in water level (drawdown/recovery) is caused due to pumping of water from the well. The change in water level with time is then interpreted to arrive at aquifer parameters. Theis (1935) was first to propose a method to evaluate aquifer parameters from the pumping test on a bore well in a confined aquifer. Since then, several methods have been developed to analyze the pumping test data (time-drawdown) under different conditions. Before we describe these methods in detail, let us recall some of the definitions, which are frequently used.