1. LO: To describe and explain the features of artesian basins and aquifers. To explain the balance between extraction and recharge of these stores. To outline the impacts of groundwater abstraction.

2. Key Terminology Artesian Basin or Aquifer: A confined aquifer containing groundwater under positive pressure. This causes the water level in the well to rise to a point where hydrostatic equilibrium has been reached (the pressure on the aquifer is equal to the pressure exerted by the aquifer). In this diagram you can see that the artesian aquifer is trapped between 2 layers of impermeable rock (aquitards). The pressure of the water on these layers is equal to the pressure of water recharge (from the surface) and water abstraction (via drilling boreholes or wells). As a result, the water level is maintained.

4. Complete this systems diagram… GROUNDWATER (STORE) INPUTS (RECHARGE)OUTPUTS (ABSTRACTION) Artificial Naturall Natural https://www.youtube.com/watch?v=25sWFuAYSVc&t=575 https://www.youtube.com/watch?v=eCMOz70t2ZU&t=174

5. CAUSES OF GROUNDWATER ABSTRACTION OR RECHARGE Evapotranspiration from shallow stores (unconfined aquifers), capillary action will draw moisture up to near the surface. Natural discharge by springs into lakes, rivers and oceans. Artificial abstraction (removal) for domestic, industrial and agricultural use. Leakage into nearby aquifers. Inter-basin transfers. Geologic or tectonic movements. Artificial recharge. Either leakage from irrigation channels and reservoirs or the pumping of water into aquifers. Infiltration and percolation after precipitation or snow melt. Seepage from river channels, lakes and oceans. Excessively high precipitation. Leakage from nearby aquifers. Inter-basin transfers. Permeable or fractured geology.

6. Think back to the Sonoran Desert… Using the causes of RECHARGE or ABSTRACTION, identify what processes can affect the levels of groundwater in the Sonoran Desert.

7. An additional case study… Great Artesian Basin, Eastern Australia Describe its location. Explain why it is there. Outline why it is important to manage this water store. https://www.youtube.com/watch?v=wSdtIRGjiPk

8. Environmental impacts of groundwater abstraction… 1. Seawater Intrusion 2. Subsidence 3. Pollution (due to concentration levels) 4. Altered river hydrology http://www.eea.europa.eu/data-and-maps/indicators/saltwater-intrusion http://www.geotimes.org/july01/sinking_titanic_city.html http://www.sundaytimes.lk/141109/sunday-times-2/save-the-treasure-hidden-underground-126627.html http://www.livemint.com/Politics/55tZIXk1ov2ADNcLnVZRwN/Farmers-fight-CocaCola-as-Indias-groundwater-dries-up.html http://grist.org/article/table/