Presentation on theme: "Diana L. Duckworth Rustburg High School Campbell County Schools"— Presentation transcript:
1Diana L. Duckworth Rustburg High School Campbell County Schools GroundwaterDiana L. DuckworthRustburg High SchoolCampbell County Schools
2Key Concepts Porosity: percentage of the rock that is empty space Depends on grain size, shape, & sortingPermeability: ability of a rock to yield waterDepends on grain size (larger grains have larger pores), grain shape, & sortingLarge pores, less impact of frictionRounded grains, larger poresPoor sorting, small grains fill in pores & reduce permeability
3Distribution of Water Underground Zone of AerationPores filled with airWater TableSurface of Zone ofSaturationPore space filledWith waterWater infiltrates ground when it rains. Percolates downunder the force of gravity.
4Water table reaches surface at springs, rivers, & lakes Water table follows the shape of the land.Water flows downhill underground.LakesRiverSide ViewWater flows from high ground intostreams, lakes & marshes.
5Man’s Usage of Groundwater Two kinds of wells:Ordinary well that requires pumpingArtesian well where water rises to surface without pumpingRecharge AreaAquacludeArtesian Aquifer
6Two water levels Ordinary Wells Static water level Pumping water level DrawdownCone ofdepressionSide View
7Problems with Overexploitation Withdrawals in excess of recharge rates:Artesian wells lose pressure, must be pumpedOrdinary wells can produce overlapping cones of depressionLead to dewatering of aquiferLower stream levels in droughtSalt water intrusion in coastal areasislandoceanlagoonSalt water tableFresh waterfloats on salt water
8Hillside Springs Perched water table Spring Aquaclude Roaring Springs, North RimGrand Canyon
9Groundwater Budget Income = precipitation Outgo = runoff + evapotranspirationSurplus: precipitation is greater than evapo-transpiration & runoffWater table risesDeficit: precipitation is less than evapo-transpiration & runoffWater table fallsSteady state: precipitation = evapotranspiration & runoffWater table stays steadyWater Balance Equation P = E + R + GWhere G = change in water table
10Caves CO2 dissolves in groundwater Dry caves Becomes acidic Dissolves limestoneJoints enlarged into cavesDry cavesDripping water evaporatesCreates stalactites & stalagmites
11Sinkholes Roof of cave collapses Leaves circular depression May fill with waterMap viewsinkholecaveSIDE VIEW
12Groundwater Topography Karst topographySinkholesCavernsDisappearing streamsPonds with no surface outletLimestone terrain