Water well testing consists of pumping groundwater from a well, usually at a constant rate, and measuring water levels in the pumped well and any nearby wells (observation wells) or surface water bodies during and after pumping.
A pumping test is a practical, reliable method of estimating well performance, well yield, the zone of influence of the well and aquifer characteristics (i.e., the aquifer’s ability to store and transmit water, aquifer extent, presence of boundary conditions and possible hydraulic connection to surface water).
Aquifer test and aquifer performance tests (APT) are alternate designations for a pumping test. In petroleum engineering, a pumping test is referred to as a drawdown test.
Purpose of conducting Aquifer Tests:
Hydrogeological studies include the determination of aquifer parameters by conducting pumping tests on dug/bore/tube wells and analysis of pumping test data.
Basically, pumping tests are conducted for a wide variety of reasons, including the following:
- To determine the reliable long-term yield (or ‘safe’ yield) of a borehole.
- To assess the hydraulic performance of a borehole, usually in terms of its yield-drawdown characteristics. How much drawdown does it take to yield a certain amount of water?
- To derive the hydraulic properties of the aquifer.
- Pumping tests are the classic (and perhaps the only) way to derive in situ aquifer hydraulic properties, such as transmissivity and the storage coefficient, or to reveal the presence of any hydraulic boundaries.
- To test the operation of the pumping and monitoring equipment.
- To determine the effects of abstraction on neighboring abstractions (sometimes referred to as derogation).
- To determine the environmental impact of the abstraction.
- To provide information on water quality. Is the water quality suitable for the intended use? Are there likely to be any problems such as drawing in saline or polluted water after extended periods of pumping?