TAILIEUCHUNG - Groundwater Pollution

The population elasticity is now slightly below one at . A higher rate of urbanization has the expected positive impact on emissions. The share of population in the economically active age groups now becomes marginally insignificant. The reason for this could be the high correlation between the two variables (partial correlation coefficient of ). Lastly, in column V we add the average household size to our model. Note that this variable is available for all countries in the sample, but not over the entire estimation period. Hence the number of observations is smaller in column V than in the other regressions. The population elasticity is again very close to unitary | Groundwater Pollution 1 Water Pollution III Types of Aquifers Groundwater Flow Physics -ỳ Darcy s Law and Hydraulic Gradient -ỳ Movement of Underground Plumes -ỳ Cleanup Stormwater Flows -ỳ Contamination Sources -ỳ Impacts Solutions 2 Groundwater Pollution Facts 1980 Comprehensive Environmental Response Compensation and Liability Act CERCLA more commonly known as Superfund. 300 000 - 400 000 sites need remediation. Many can be cleaned up for - 100 000 but some require millions. Total trillion dollars. -ỳ The annual Gross Domestic Product GDP is currently 10 trillion dollars. 3 To date roughly 10 billion has been spent on superfund site remediation. 1984 Resource Conservation and Recovery Act RCRA . This legislation hopes to avoid more superfund sites. Groundwater structure Unconfined aquifers typically bounded below by a non-porous layer but are not bounded above. Confined aquifers sandwiched between two rock layers. 6 The quantity of water in an aquifer is determined by its porosity. Porosity 77 volume of voids volume of voids and solids - Fails to account for the amount of water that will be retained due to surface tension at the solid interfaces. The specific yield tells the amount of water that can actually be withdrawn of the total volume . Material Porosity Specific Yield Clay 45 3 Sand 34 25 Gravel 25 22 Gravel and Sand 20 16 Sandstone 15 8 Limestone or Shale 5 2 Quartz or Granite 1 For an aquifer of sand with cross sectional area of 1 m2 and depth of 2 m the volume of water is Volume of water Porosity Vol. of material X 2 m3 m3 Yield of water Specific yield Vol. of material X 2 m3 m3 8 Groundwater Flow The hydraulic gradient is defined as Hydraulic gradient L Where hi are the vertical heights L is the horizontal distance. The gradient is dimensionless and can be expressed as Hydraulic gradient dL 9 Darcy s Law for flow through porous media Q KA - dL Q flow rate m3 day K hydraulic conductivity m day A cross-sectional area m2 .

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