Abstract:
As the construction of shallow well is cheap and possible almost everywhere, shallow well has long been exploited as ground water development for consumption since the ancient time. However there still lack of studies and proper technical guidelines about the yield characteristics of shallow well. Nowadays, the usage of shallow well is increasing and extends into farm irrigation which involves a sizable investment. This might probably lead to the risk of improper investment as well as reduction of benefit. This study presents a method for characterization and estimation of yield of shallow wells by using data from the pump test. Drawdown, well diameter and average grain size of soil layers of the aquifer are used as the characteristic parameters affecting the yield of a shallow well. Another characteristic parameter, i.e. the specific discharge, is introduced to ease the characterization of a shallow well. The study is made using data obtained by the pump test from 22 shallow wells in Amphoes Muang and Borabue in Changwat Mahasarakham. Several methods are proposed to analyse the correlation or relationship among the characteristic parameters in the forms of equations or graphs. The results reveal that the proposed parameters provides definite and proper characterization of a shallow well which can be used in practice. Furthermore, the relationships of the well discharge and drawdown and of the specific discharge and drawdown with some specific grain size are also given in the forms of log-log graphs. These relationships can be used as technical guidelines for the design and planning of the development of shallow wells. Such application may well lead to reduction of risk of such development.