![Page 1: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/1.jpg)
Groundwater
Hydraulic Gradient
Groundwater
• Pore spaces
• Joints/fractures
Water Table
Recharge
Saturated zone
![Page 2: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/2.jpg)
Aquifers
Impermeable rock
Groundwater
Pore spaces unsaturated
Pore spaces saturated
![Page 3: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/3.jpg)
What rocks in the UK make good aquifers?
Sandstone40% porosity
30% specific yield
High permeability
Clay
45% porosity
3% specific yield
Low permeability
![Page 4: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/4.jpg)
Impacts of pumping water from aquifers
![Page 5: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/5.jpg)
Impacts of pumping water from aquifers
Drawdown
Hydraulic Gradient
Cone of Depression
![Page 6: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/6.jpg)
Impacts of pumping water from aquifers
Saline wedge
Control – reduce/stop abstraction, change pattern of abstraction ( winter not summer) or move borehole
Monitoring – chemical testing (boreholes/salinity testing)
![Page 7: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/7.jpg)
Agriculture
• Nitrates
• Pesticides
Industry
• Chemical leaks
• Chemical spills
• Contamination from chemical storage
Waste Disposal
• Leachates from landfill sites
• Radioactive waste
Contamination of aquifers
![Page 8: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/8.jpg)
Contamination of aquifers
Chloride content (milligrams per litre) of leachate
Monitoring
• chemical testing of water from boreholes, springs, extraction wells• ground penetrating radar (remote sensing methods)
• electrical resistivity analysis (oil pollutants = high resistivity)
• soil gas chemical monitoring (organic pollutants give off a vapour such as methane)
borehole
Most expensive
Cheapest
![Page 9: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/9.jpg)
Contamination of aquifers
1. Control
• clay liner
• synthetic liner
• leachate collection
total containment
![Page 10: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/10.jpg)
Contamination of aquifers
2. Control
• build barriers to plume
• trenches filled with concrete
• hammered piles injected with cement grout
Barrier to predicted depth of pollution
Pollution localised
10 – 20m max
![Page 11: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/11.jpg)
Contamination of aquifers
3. Control
• pump pollutant to surface for treatment/disposal
![Page 12: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/12.jpg)
Contamination of aquifers
4. Control
• direct polluted groundwater into to bioreactive barrier
• bioreactive barrier use naturally occurring bacteria to breakdown the pollutant
• oxygen & nitrates injected into barrier to encourage decay processes
factory
pollutant
Impermeable wall to direct groundwater
Bioreactive filter
![Page 13: Groundwater Hydraulic Gradient Groundwater Pore spaces Joints/fractures Water Table Recharge Saturated zone](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00f1a28abf838cca411/html5/thumbnails/13.jpg)
Key Terminology:
1.Aquifer2.Confined aquifer3.Groundwater4.Water table5.Porosity6.Permeability7.Specific yield8.Hydraulic gradient9.Recharge10.Cone of depression11.Drawdown12.Contamination plume13.Ground penetrating radar14.Electrical resistivity15.Soil-gas monitoring16.Bioreactive barrier