The value and interpretation of groundwater level measurements

Abstract

AbstractThe measurement of water levels in the ground is a routine part of groundwater resource assessments and most site investigations. However the techniques used are often inadequate to reveal the true behaviour of aquifers, often resulting in inadequate data or a large number of expensive but useless readings. Continuous recording of groundwater levels using both float-operated chart recording and electric pressure transducers have been made on a wide range of observation wells to determine the most economical frequency of measurement for different aquifers and different purposes. The results of the investigation revealed a number of factors which are relevant in the observation of groundwater levels and these are discussed. Of these the construction of the observation point in the form of an open observation well, tube well, standpipe or one of a variety of piezometers is of fundamental importance. The behaviour of the aquifer as confined, or unconfined, with or without perched water tables, has considerable bearing on the results obtained. Barometric, tidal, fluvial, seasonal and abstraction effects on groundwater levels are discussed with reference to the amplitude of groundwater fluctuation and its rate of change. Finally suggestions are made for the design of observation points and the frequency of readings for different applications.