The most common methods of measuring water level are as follows: The basic equipment to measure the two parameters in pumping test (water level in the pumped borehole and the rate at which water is being pumped) are as follows: From the logs of these wells, it may be possible to derive approximate values of the aquifer’s transmissivity and storativity and their spatial variation Data on the groundwater-flow system: horizontal or vertical flow of groundwater, water table gradients, and regional trends in groundwater levels.Any lateral recharge boundaries (e.g., where the aquifer is in direct hydraulic contact with a deeply incised perennial river or canal, a lake, or the ocean) or any horizontal recharge boundaries (e.g., where percolating rain or irrigation water causes the water table of an unconfined aquifer to rise, or where an aquitard leaks and recharges the aquifer).The aquifer may be bounded laterally by barrier boundaries of impermeable material (e.g., the bedrock sides of a buried valley, a fault, or simply lateral changes in the lithology of the aquifer material).The thickness and lateral extent of the aquifer and confining beds:.The type of aquifer and confining beds.The geological characteristics of the subsurface i.e., all those lithological, stratigraphic, and structural features that may influence the flow of groundwater.Information about the borehole or well that is about to be tested.To optimize operational pumping regimes (especially from multiple-borehole sources), including selecting the most suitable pumping plant for long-term use, and estimating probable pumping and/or treatment costs.īefore commencing any pumping test, there are certain basic preparations that should be made.Is the water quality suitable for the intended use? Is it stable in the long term? Are there likely to be any problems such as drawing in saline or polluted water after extended periods of pumping? To provide information on water quality. All groundwater abstraction eventually has an impact it is only a matter of where, when and whether or not the impact is acceptable. To determine the environmental impact of the abstraction.To determine the effects of water abstraction on neighboring abstractions.To test the operation of the pumping and monitoring equipment, to make sure that everything is working safely and efficiently, and if applicable, to confirm that the contractors have done their job properly.To derive the hydraulic properties of the aquifer, such as transmissivity and the storage coefficient, or to reveal the presence of any hydraulic boundaries.How much drawdown does it take to yield a certain amount of water? To assess the hydraulic performance of a borehole, usually in terms of its yield-drawdown characteristics.To determine the reliable long-term yield (or ‘safe’ yield) of a borehole, and therefore whether or not the borehole can be regarded as a ‘success,’ and how many people it will be able to supply.Pumping tests can be undertaken for a wide variety of reasons, including the following: The way in which the water levels respond to the pumping is then analyzed to derive information about the performance characteristics of the borehole and the hydraulic properties of the aquifer. Two sets of equations are presented, one for assumed laminar flow and one for assumed turbulent flow.Pumping tests or aquifer performance tests is a field experiment in which a well is pumped at a controlled rate and water-level response (drawdown) is measured in one or more surrounding observation wells and optionally in the pumped well (control well) itself. These are plotted logarithmically and evaluated according to the procedures outlined in the report. The SDT consists of 4 to 5 pumping stages of 30 to 120 minutes each. The suggested field procedure for a complete well test is to first carry out an air-lift pumping test, then a 1-hour discharge test, then the SDT, then the recovery test. The Step Draw-Down Pumping Test (SDT) was developed by Jacob to determine aquifer transmissivity and well properties in cases where the standard method is inapplicable, for example, the absence of observation wells. Water and engineering technical information bulletinĪquifers, hand pumps, models, testing, well yield
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