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<br />CONCEPT 13: Pumping wells draw water toward them from all directions and <br />lower the water table (Qroundwater withdrawal). The unsaturated zone around <br />the well is called the cone of deoression or drawdown zone. <br /> <br />Action: Continue to pump water from one of the two pumping wells in the <br />unconfined aquifer. Watch the water level in the other pumping well and <br />the nearby piezometer. <br /> <br />Discussion: Pumping the well causes a zone around it to become <br />unsaturated. This unsaturated Zone is called the cone of depression. <br />The cone of depression is 3-dirnensional. <br /> <br />CONCEPT 14: DrawinQ water from a well can interfere with the ability of <br />neiQhborinQ wells to withdraw water when those wells are located in the same <br />aauifer. <br /> <br />'Action: Pump water from one of the pumping wells in the unconfined <br />aquifer. Observe the other well and any nearby piezometers and note <br />what happens to the water levels as you pump from the one well. <br /> <br />Discussion: The water levels will drop in the second pumping well and <br />one or more of the piezometers in the unconfined aquifer. If students <br />pump from the lower well, the upper well will go dry. <br /> <br />CONCEPT 15: Overdraft results when more groundwater is removed (withdrawn) <br />than is replaced (recharQed). <br /> <br />Action: Pump water from one of the wells and allow the one-liter bottle <br />to empty. As the students continue to pump water from the unconfined <br />aquifer, the water table will continue to drop. <br /> <br />Discussion: Any time people remove more water from the ground than is <br />put back into the ground, the water table will continue to drop. Wells <br />will have to be drilled deeper if the water level falls below the bottom <br />of their well. <br /> <br />CONCEPT 16: WithdrawinQ water from a well in the unconfined aauifer will not. <br />affect water in a well located in a confined aQuifer and vice versa. <br /> <br />Action: Keep the one-liter bottle inverted in the inlet. Pump water <br />from one of the pumping wells in the unconfined aquifer. Watch the <br />water level in the piezometer and pumping well in the confined aquifer. <br />There should be little or no change in the water levels. <br /> <br />Action: Keep the one-liter bottle inverted in the inlet. Pump water <br />from the pumping well in the confined aquifer. Watch the water level in <br />the piezometers and pumping wells located in the unconfined aquifer. <br />Their water levels should not change. <br /> <br />Discussion: The confining layer acts as a barrier between the confined <br />and unconfined aquifers. Therefore, removing water from the unconfined <br /> <br />5 <br />