Water Table Drawdown

Experiment - Water Table Drawdown

When a water well is constructed a hole is drilled into the ground down to and below the water table. A well casing (metal pipe) is placed in the hole and a pump is lowered into and below the water table. The static water table is the level that water stands in the well when there is no pumping.

If you click the power switch on the pump you can see the effect the pump has on the water table. As more water is pumped the water level goes down around the pump. Water is flowing into the intake screen of the pump and is then pushed up and out of the well. Additional water must flow through the material comprising the aquifer (sand, gravel, limestone, etc.) to get to the pump so that it can be pumped out. The velocity that water moves to the pump is given by the saturated hydrologic conductivity of the aquifer material. The harder it is for water to flow through the aquifer material the greater is the drawdown. When the drawdown causes the water table to come down to the level of the intake screen of the pump the pump cannot pump any more water and must be turned off till the water table raises or the pump needs to be placed at a lower level. Sometimes this will require that the well be drilled deeper.

To conduct the experiment:

1. Select soil type
2. Turn on the pump

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