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Diana L. Duckworth Rustburg High School Campbell County Schools

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Presentation on theme: "Diana L. Duckworth Rustburg High School Campbell County Schools"— Presentation transcript:

1 Diana L. Duckworth Rustburg High School Campbell County Schools
Groundwater Diana L. Duckworth Rustburg High School Campbell County Schools

2 Key Concepts Porosity: percentage of the rock that is empty space
Depends on grain size, shape, & sorting Permeability: ability of a rock to yield water Depends on grain size (larger grains have larger pores), grain shape, & sorting Large pores, less impact of friction Rounded grains, larger pores Poor sorting, small grains fill in pores & reduce permeability

3 Distribution of Water Underground
Zone of Aeration Pores filled with air Water Table Surface of Zone of Saturation Pore space filled With water Water infiltrates ground when it rains. Percolates down under the force of gravity.

4 Water table reaches surface at springs, rivers, & lakes
Water table follows the shape of the land. Water flows downhill underground. Lakes River Side View Water flows from high ground into streams, lakes & marshes.

5 Man’s Usage of Groundwater
Two kinds of wells: Ordinary well that requires pumping Artesian well where water rises to surface without pumping Recharge Area Aquaclude Artesian Aquifer

6 Two water levels Ordinary Wells Static water level Pumping water level
Drawdown Cone of depression Side View

7 Problems with Overexploitation
Withdrawals in excess of recharge rates: Artesian wells lose pressure, must be pumped Ordinary wells can produce overlapping cones of depression Lead to dewatering of aquifer Lower stream levels in drought Salt water intrusion in coastal areas island ocean lagoon Salt water table Fresh water floats on salt water

8 Hillside Springs Perched water table Spring Aquaclude
Roaring Springs, North Rim Grand Canyon

9 Groundwater Budget Income = precipitation
Outgo = runoff + evapotranspiration Surplus: precipitation is greater than evapo-transpiration & runoff Water table rises Deficit: precipitation is less than evapo- transpiration & runoff Water table falls Steady state: precipitation = evapotranspiration & runoff Water table stays steady Water Balance Equation P = E + R + G Where G = change in water table

10 Caves CO2 dissolves in groundwater Dry caves Becomes acidic
Dissolves limestone Joints enlarged into caves Dry caves Dripping water evaporates Creates stalactites & stalagmites

11 Sinkholes Roof of cave collapses Leaves circular depression
May fill with water Map view sinkhole cave SIDE VIEW

12 Groundwater Topography
Karst topography Sinkholes Caverns Disappearing streams Ponds with no surface outlet Limestone terrain

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