Bentley WaterGEMS CONNECT Edition Help

Modeling a Pumped Groundwater Well

A groundwater well is modeled using a combination of a reservoir and a pump. Set the hydraulic grade line of the reservoir at the static groundwater elevation. The hydraulic grade line can be entered on the reservoir tab of the reservoir editor dialog box, or under the Reservoir Surface Elevation column heading in the Reservoir Report.

Pump curve data can be entered on the Pump Tab of the Pump Editor. The following example will demonstrate how to adjust the manufacturer's pump curve to account for drawdown at higher pumping rates. Drawdown occurs when the well is not able to recharge quickly enough to maintain the static groundwater elevation at high pumping rates.

Pump Curve Accounting for Drawdown:

The pump manufacturer provides the following data in a pump catalog:

Head (ft.) Discharge (gpm)
1260 0
1180 8300
1030 12400
Based on field conditions and test results, the following drawdown data is known:
Drawdown (ft.) Discharge (gpm)
40 8300
72 12400

To account for the drawdown, the pump curves should be offset by the difference between the static and pumped groundwater elevations. Subtract the drawdown amount from the pump head, and use these new values for your pump curve head data.

The following adjusted pump curve data is based on the drawdown and the manufacturers pump data:

Head (ft.) Discharge (gpm)
1260 0
1140 8300
958 12400