Presentation on theme: "Groundwater What is it and why is it important?"— Presentation transcript:
1Groundwater What is it and why is it important? Click on any number for an explanationAdapted from: “Groundwater Interactive”The Kesab Watercare Club
21. What is Groundwater? Water that runs below the earth’s surface Water found in most water bodies such as lakes, rivers, streams and wetlands is known as surface water
32. AquiferIf it weren’t for aquifers we’d be wading in water up to our waistsWater runs off into streams, lakes, ponds and aquifersAquifers are underground reservoirsWater that enters aquifersUsually is much cleaner than surface waterContains almost no bacteriaMany pollutants are filtered outTwo types of Aquifers: confined and unconfined
43. Confined AquiferAn aquifer below the surface that is saturated with waterContains layers of impermeable material both above and belowThese layers cause the water to be under pressureIf penetrated by a well the water will rise above the top of the aquifer
54. Unconfined AquiferAllows water to enter freely from above and belowCloser (generally) to the surface than confined aquifersImpacted by drought conditions sooner than confined aquifers
65. Porosity & Permeability (1) The amount of water that can be stored in an aquifer depends on two factors:Porosity: refers to the amount of pore spaces or fractures in an aquiferPorous aquifers consist mainly of loose gravel, sands and siltsWater fills any space between the gravel, sand and silt
76. Porosity & Permeability (2) Refers to the rate of infiltrationSandy soils allow quick infiltration of rainfallClay soils quickly saturate and surface flow removes most of the rainfallOnly all small portion reaches groundwaterImpermeable rock would not allow water to enter
87. Groundwater WellsGroundwater is obtained by drilling a well into an aquiferA casing or pipe is placed inside the well to stop the wall from falling inwardThe space between the casing and rough wall is filled with concrete to prevent leakingWell screen at the bottom is used to filter out sand and gravel
97. Groundwater Wells (cont’d) Once this is done a pump is inserted into the wellA well can become contaminated if not properly constructedTwo types of wellsArtesian: Comes from a confined aquiferUnconfined : comes from an unconfined aquifer
119. Groundwater Use Groundwater Industry uses: beer, soft drinks, spring water, pulp and paper. EtcMay be used as the sole water supply for stock and domestic purposesRequires minimal treatment
1210. Threats to Groundwater Groundwater is usually of excellent qualitySince it is naturally filterer it is usually clear colorless, and free from microbial contaminationA threat to groundwater is now posed by a number of soluble chemicals from urban, industrial and agricultural activitiesThese chemicals can not be completely removed by the natural filtration process
1311. Groundwater Contamination Many of the pollutants of surface water also contaminate groundwaterSurface pollutants can move through the soil and find their way into aquifersExamples are:PesticidesFertilizersMotor oilGasolineUntreated waste
1412. Groundwater SalinityThe most common cause is the replacement of perennial, deep-rooted native plants with crops and grasses
1513. Saltwater IntrusionThe key to controlling this problem is to maintain the proper balance between water being pumped from the aquifer and the amount of water recharging it.
1614. Threats to QuantityOverdraft occurs when groundwater is removed faster than recharge can replace it. This can result in;A permanent loss of some of its storage capacity.Contamination of clean water with low quality water.Drawdown A temporarily lowered water table generally caused by pumping.The water table only recovers when the supply is replenished.SubsidenceIs one of the dramatic results of over pumping.As the water table declines, water pressure is reduced.This causes the fine particles that hold water to become compacted.In addition to permanently reducing storage capacity, the land above the aquifer can dramatically be effected causing it to sink.This can damage property and fields.