Untangling the effects of urban development on subsurface storage in Baltimore

Abstract

The impact of urban development on surface flow has been studied extensively over the last half century, but effects on groundwater systems are still poorly understood. Previous studies of the influence of urban development on subsurface storage have not revealed any consistent pattern, with results showing increases, decreases, and negligible change in groundwater levels. In this paper, we investigated the effects of four key features that impact subsurface storage in urban landscapes. These include reduced vegetative cover, impervious surface cover, infiltration and inflow (I&I) of groundwater and storm water into wastewater pipes, and other anthropogenic recharge and discharge fluxes including water supply pipe leakage and well and reservoir withdrawals. We applied the integrated groundwater-surface water-land surface model ParFlow.CLM to the Baltimore metropolitan area. We compared the base case (all four features) to simulations in which an individual urban feature was removed. For the Baltimore region, the effect of infiltration of groundwater into wastewater pipes had the greatest effect on subsurface storage (I&I decreased subsurface storage 11.1% relative to precipitation minus evapotranspiration after 1 year), followed by the impact of water supply pipe leakage and lawn irrigation (combined anthropogenic discharges and recharges led to a 7.4% decrease) and reduced vegetation (1.9% increase). Impervious surface cover led to a small increase in subsurface storage (0.56% increase) associated with decreased groundwater discharge as base flow. The change in subsurface storage due to infiltration of groundwater into wastewater pipes was largest despite the smaller spatial extent of surface flux modifications, compared to other features.

Coupling of the Water Cycle with Patterns of Urban Growth in the Baltimore Metropolitan Region, United States

“…Inputs to the ParFlow model included topographic data to derive surface drainage direction, and hydraulic conductivity and porosity for fractured bedrock, saprolite, soil, and Atlantic Coastal Plain aquifers and confining units. Data were derived from state well records, SSURGO (http://soildatamart.nrcs.usda.gov/USDGSM.aspx), and literature sources (see Bhaskar et al ., , for details). Input datasets for CLM included meteorological forcing data (derived from the North American Land Data Assimilation System Phase 2 (NLDAS‐2), http://mirador.gsfc.nasa.gov) as well as land cover, which affects evapotranspiration through properties such as leaf area index.…”

“…Input datasets for CLM included meteorological forcing data (derived from the North American Land Data Assimilation System Phase 2 (NLDAS‐2), http://mirador.gsfc.nasa.gov) as well as land cover, which affects evapotranspiration through properties such as leaf area index. For urban areas, we included fluxes of estimated lawn watering rates, water supply pipe leakage, infiltration and inflow of groundwater and rainwater into wastewater pipes, residential and municipal well pumping, and reservoir withdrawals (Bhaskar et al ., ).…”

“…Bhaskar et al . () used scenarios to isolate the effects of these urban processes and impervious surfaces on subsurface storage, finding that impervious surfaces play a relatively minor role in decreasing subsurface storage compared to loss of groundwater to the wastewater system. We used the final output from the simulation in which all urban processes were represented, referred to as the “base case” in Bhaskar et al .…”

Predictors of urban variable source area: a cross‐sectional analysis of urbanized catchments in the United States

“…Contrary to commonly held beliefs about limiting imperviousness of development in order to avoid negative changes in hydrologic regime, studies indicate that developed open space can also have limited ability to prevent flashy response. Reasons for this include the limited infiltrative capacity of compacted soils (Smith and Smith, ), high proportion of runoff response attributed to shallow subsurface flow under residential lawns (Wigmosta and Burges, ), subsurface saturation due to leaky water distribution infrastructure (Lerner, ) and decreased evapotranspiration associated with vegetation change (Bhaskar et al ., ). Figure shows an adaptation of the VSA to include urban run‐on from impervious areas and other potential sources of impacts to soil saturation in urbanized catchments (Miles and Band, ).…”

Urban outdoor water use and response to drought assessed through mobile energy balance and vegetation greenness measurements

“…USDA is an equal opportunity provider and employer.Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. and the effect of policies for managing water resources (Bhaskar et al 2015, Vahmani and Hogue 2014, Shaffer et al 2015, Pataki et al 2011a. With increasing droughts and competition for water among urban, agricultural, and in-stream uses, considering the water requirements embodied within ecosystem services is essential.…”