![]() ![]() forgetting to keep units consistent (i.e. What would be a common error in this example? h Height of water table in unconfined aquifer (m). ![]() Transmissivity calculator allows variety of units) b Confined aquifer thickness (m). The results should look as follows (with units of m-d): The values in the drop-down menu in our transmissivity calculator are typical numbers within the ranges given below for clayey, silty, sandy, and gravelly soil. The test will run for 1 day, and monitoring will occur approximately every 3 hours. With a pumping rate of 2730 m 3/d, what would be the expected drawdown at a monitoring well 122 m away. The intention of the upcoming pump test is to double check these estimates. Use this moment to make a note of your pump’s flow rate and run time. While this is considered an estimate and more. Pump flow rate of 20+ GMP: 2.0 GPM of run time. If the well has an available drawdown of 50 feet, the maximum pumping rate would be 5 times 50 feet, or 250 gpm. Pump flow rate of 10-20 GPM: 1.5 GPM of run time. They have results from a pump test conducted two decades earlier, indicating a transmissivity of 1250 m 2/d and a storage coefficient of 1.9x10 -4. Pump flow rate of 0-10 GPM: 1.0 GPM of run time. Your browser does not support inline frames or is currently configured not to display inline frames.Ī consultant is preparing to conduct a pump test at a local well field. T (elapsed time since the start of pumping): The Cooper-Jacob approximation is given by: This calculator is good for anticipating results from pump tests. The Cooper-Jacob calculator presented here estimates the drawdown for a given well location over time. COOPER-JACOB APPROXIMATION An approximation of the Theissian Model for Pumping Test Interpretation Back to CalculatorsĬooper and Jacob (1946) developed an approximation for the Theis equation and a data analysis method which does not require type-curve matching. The Drawdown in aquifer for total drawdown is a term applied to the maximum lowering of the groundwater table caused by pumping or artesian flow is calculated using Change in Drawdown Total Drawdown-Well loss.To calculate Drawdown in aquifer for total drawdown, you need Total Drawdown (s t) & Well loss (CQ n). ![]()
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