This work quantifies the impacts of urban development on groundwater storage and groundwater-surface water interactions using intensive data analysis and mathematical modeling. The monthly water balance for the period 2000-2009 for 65 Baltimore area watersheds was calculated using remote sensing data and the dense network of instrumented sites in this region. This analysis included estimation of spatially-distributed anthropogenic fluxes (water supply pipe leakage, lawn irrigation, and infiltration and inflow (I&I) of groundwater and stormwater into wastewater pipes) as well as natural fluxes of precipitation, streamflow, and evapotranspiration. Inflow fluxes of water supply pipe leakage and lawn irrigation were significant but small compared to precipitation, but I&I was approximately equal to gaged streamflow. Building on knowledge of the altered water balance, an integrated hydrologic model of the Baltimore metropolitan region was developed to quantify the impact of urban development on groundwater storage. The three-dimensional groundwater-surface water-land surface model ParFlow.CLM was implemented and a methodology to incorporate urban and hydrogeologic input datasets was developed. Using the model, the impacts of reduced vegetative cover, impervious surfaces, I&I, and other anthropogenic discharge and recharge fluxes were isolated. Removal of I&I led to the largest change in storage, and removal of impervious surface cover had the smallest effect. To investigate the relationship between pre-event water proportion, storage, and streamflow at small watershed scales spanning a gradient of urbanization, chemical hydrograph separation, hillslope numerical experiments, and simple dynamical systems analysis were utilized. From analysis of high-frequency specific conductance data, the pre-event water proportion of stormflow was found to be greatest for storms with higher total precipitation. Using the simple dynamical systems approach, watersheds with larger percentages of impervious surfaces were found to have the largest sensitivity of streamflow to changes in storage. HydroGeoSphere, a three-dimensional groundwater-surface water flow and transport model, was implemented in an idealized hillslope and showed that the relationship between streamflow and storage was clockwise hysteretic. Overall this work demonstrates the importance of infrastructure leakage on urban hydrologic systems and shows that pre-event water contributions of stormflow are primarily related to precipitation and not initial storage in urban watersheds.
|Commitee:||Eshleman, Keith, Ghosh, Upal, Maxwell, Reed M., Miller, Andrew J.|
|School:||University of Maryland, Baltimore County|
|Department:||Engineering, Civil and Environmental|
|School Location:||United States -- Maryland|
|Source:||DAI-B 75/05(E), Dissertation Abstracts International|
|Subjects:||Hydrologic sciences, Civil engineering|
|Keywords:||Anthropogenic, Groundwater, Modeling, Storage, Urban|
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