Atrium Lobby (Hyatt Regency Baltimore on the Inner Harbor)
Understanding the effects of urbanization on the groundwater and the hydrologic cycle are important for effective water management. We present results from a regional water sustainability project in the Baltimore region. We present applications of ParFlow, a coupled three-dimensional, variably saturated subsurface and surface flow model to date at two scales: (1) the Gunpowder-Patapsco basin, which encompasses much of the Baltimore metropolitan region (13,200 sq km domain size), and (2) Dead Run, a small highly urban watershed embedded within the Gunpowder-Patapsco watershed, at the edge of Baltimore City (72 sq km domain size). At the smaller Dead Run scale, the model, and particularly the overland flow component, was highly sensitive to landscape form and urbanization. We found that enforcement of topographic slopes to follow channels was necessary as the topography alone was not adequate to define the drainage in this flat, urban domain. Furthermore, we found including some individual piped streams— features that do not register on any Digital Elevation Model (DEM)— was required for the domain to drain properly. Elevations from a DEM in an urban landscape may not be able to adequately define surface flow paths as streams may have been moved, channelized, piped underground, or otherwise modified. We also are quantifying human modifications of the water balance in urbanized watersheds, including water distribution pipe leakage, infiltration and inflow, and water withdrawals from reservoirs. Comparing these to the natural water balance components can be used to add the most significant human changes to the model of the Baltimore region, as well as answering the question of whether this urbanization is a net source or sink in the water balance. In future work, this watershed model will be coupled to an urban growth model of the Baltimore metropolitan region to explore the feedbacks between water availability and future development.
