Outline # 6 Groundwater H ydrology ESS 315/POE 313 I. Grou ndwater Suppl y and Hydrogeological Properties Groundwater Supply -Global Hydrologi c Cycle -groundwater recharg e = precipitatio n - (run off + ET) Think about what factor s influence soi l infi ltration? -National Use -Washington State Use Location an d Distributio n of Groundwater - zones o f aeration , saturation and water table -aquifers vs aquicludes -springs Hydrologic Properties -porosity: ratio ofthe volume ofpore spaces in a rock or othe r solid to the material’s total vol ume. -specific retention: ratio of volum e of water retain ed to tota l volume of rock/so -specific yield: water yielding capacity (volume ofwater, afte r saturation , that can be drained by gravity to the t otal volume of the aquifer , as a percentage) drained by grav ity to the tota l -permeability: measure ofvelocity of a flui d as it flowsthrough a porous medium. ( Darcy’s Law ) Q= K x I x A ; Q rate of flow, K hydraulic conductivity, I hydrauli c gradient , A cross-sectional area Groundwater Storage and Management -quantity o f water store d in the basin and sustained yield -groundwater minin g:amount of water withdraw n from aquifer exceeds aquifer sustained yield (e.g . High Plains aquifer) -saltwater intrusion: Ghyben-Herzberg lens Water Quality -potable water standards: (U.S. public health service) -dissolved substanc es -pollutants Conservation and A lternative Sources -conservation -desalinization -artifical recharge