INTEGRATION OF URBAN RECHARGE ESTIMATES (AUSTIN, TEXAS) INTO A DECISION SUPPORT SYSTEM

Over 50% of the global population dwell in urban areas and this percentage is projected to increase over time. Concomittant increases in water resource demands and environmental consequences require effective analyses of urban groundwater systems that can be integrated into management and planned development of cities. Recent studies show that recharge can increase with urbanization due to anthropogenic sources that include utility lines, storm sewer systems, stormwater catchments, irrigation of lawns, parks, and golf courses. Stormwater catchments capture stormwater runoff in urbanized areas to filter out contaminants, lower overland flow, and recharge groundwater resources. Built to mimic pre-development hydrologic conditions, the effect of these structures in a particular watershed depends on the abundance, design of each structure, and proximity to the aquifer. Prior analyses using a groundwater decision support system (GWDSS) evaluated the effects of impervious cover on water balance in Austin, Texas, but incuded neither contributions to recharge from stormwater catchment basins nor the effect of secondary permeability of impervious cover. We refine the recharge calculation embedded within GWDSS by incorporating a range of hydraulic conductivities and infiltration rates. The updated parameterization for recharge was determined with both field measurements and literature data. The modified recharge calculations in the GWDSS generate candidate strategies for management and groundwater allocation policies. Analyses meld field measurements with simulation-optimization to delineate the role and significance of engineered stormwater catchment basins on urbanized watersheds and available aquifer yield. A set of 10,256 candidate solutions were compared using two different recharge scenarios: a baseline and a modified recharge verison. The modified version incoporated effects from stormwater ponds, the secondary permeablility of impervious cover, and utility lines. Results show that anthropogenic sources can significantly increase the sustainable yield of aquifers found in an urban setting.