Urbanization changes the natural response of watersheds by increasing rainfall runoff volume and reducing groundwater recharge. Groundwater is an important source of municipal and agricultural waters supplies, especially in arid regions like Southern California, and urban runoff is a significant source of surface water impairment. A method to mitigate these impact is to infiltrate stormwater using a drywell. The main advantages of a drywell are the limited need for space and minimal losses to evaporation. The primary disadvantage is clogging, which leads to reduced infiltration performance over time. A major source of clogging is colloidal solids that are often present in drywell influent. This study simulates the performance of an infiltration device receiving sediment laden inflow using Chain 2D, a vadose zone flow and transport model. The Chain 2D model was modified to incorporate changes in soil unsaturated hydraulic conductivity due to the transport and retention of colloidal solids in the grain matrix, which leads to clogging. The drywell simulations are used to predict the severity of clogging over a range of land use types and to assess the effectiveness of pretreatment to reduce clogging. For the simulations performed, biofiltration and media filtration were found to be effective in reducing clogging due to sediment laden runoff from commercial, transportation, or rural land uses.
|Commitee:||Leij, Feike, Bradford, Scott A., Sasidharan, Salini|
|School:||California State University, Long Beach|
|School Location:||United States -- California|
|Source:||MAI 81/4(E), Masters Abstracts International|
|Subjects:||Civil engineering, Engineering|
|Keywords:||Clogging, Colloidal, Drywell, Infiltraion, Unsaturated, Vadose zone|
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