Northeastern Section - 44th Annual Meeting (22–24 March 2009)

Paper No. 3
Presentation Time: 8:40 AM

A DECISION-SUPPORT TOOL TO ASSESS WATER AVAILABILITY AT UNGAGED SITES IN MASSACHUSETTS


ARCHFIELD, Stacey A.1, VOGEL, Richard M.2, STEEVES, Peter A.3, BRANDT, Sara L.3, WEISKEL, Peter K.3 and GARABEDIAN, Stephen P.4, (1)National Research Program, U.S. Geological Survey, Reston, VA 20192, (2)Civil and Environmental Engineering, Tufts University, Medford, MA 02155, (3)Massachusetts-Rhode Island Water Science Center, U.S. Geological Survey, Northborough, MA 01532, (4)Silvio O. Conte Anadromous Fish Research Laboratory, U.S. Geological Survey, Turners Falls, MA 01376, sarch@usgs.gov

Federal, State and local water-supply, regulatory, and planning agencies require easy-to-use, technically defensible decision-support tools that can evaluate the effects of existing and proposed water withdrawals, compute flow statistics, evaluate baseline streamflow conditions needed for sustaining the health of the ecosystem, and estimate inflows to drinking-water-supply reservoirs for safe yield analyses at ungaged locations. In cooperation with the Massachusetts Department of Environmental Protection, an interactive, point-and-click decision-support tool was developed in combination with a geographic-information system to address these needs.

This decision-support tool estimates unregulated and regulated daily streamflow at any user-selected location along a perennial stream in Massachusetts. Users can estimate water availability and test water-management scenarios for an ungaged basin by comparing estimated streamflows to user-specified, time-varying ecological-flow targets or by simulating changes in water use at individual withdrawal points. A spatially-referenced database of ground- and surface-water withdrawals, ground-water discharges, and National Pollutant Discharge Elimination System (NPDES) return flows was populated statewide. For a user-selected basin, the effects of ground- and surface-water withdrawals and discharges are subtracted and added, respectively, from the unimpacted, daily streamflow to obtain a time series of regulated, daily streamflow at an ungaged location. Users also have the option to apply an analytical solution to time-varying ground-water withdrawals and discharges that considers the effects of the aquifer properties on the timing and magnitude of streamflow alteration by water use. New methods were developed to estimate unregulated, daily flow-duration curves and time series of streamflows at ungaged sites. Estimated unregulated and regulated daily streamflows show good agreement with observed unregulated daily streamflows and compare reasonably well with the results obtained from a calibrated rainfall-runoff model.