Water Resources Research Act Program

Details for Project ID 2017CT306B

Integrating fine-scale field measurements with regional groundwater models to predict legacy nitrogen transport in Long Island Sound watersheds

Institute: Connecticut
Year Established: 2017 Start Date: 2017-03-01 End Date: 2018-02-28
Total Federal Funds: $13,831 Total Non-Federal Funds: $32,504

Principal Investigators: Ashley Helton, Jeffrey Starn, Martin Briggs

Abstract: Nitrogen (N) loading to the Long Island Sound (LIS) has been identified as the primary cause of seasonal hypoxia and is the focus of extensive management efforts. Despite substantial improvements in wastewater treatment, N loads in the LIS remain elevated. Recent work suggests that this lack of improvement may result from temporal and spatial lags between upland management actions and coastal load reductions introduced by groundwater transport. Our ongoing work focuses on developing a regional groundwater flow and N model to quantify the temporal and spatial lags of “legacy N” (N applied to land surfaces that is transported through the groundwater system before being discharged to surface waters) for the Farmington and Housatonic River watersheds, two tributaries to the LIS. However, existing datasets of groundwater discharge rates and chemistry are sparse, and typical model calibration and verification techniques do not incorporate finer-scale patterns of groundwater-surface water exchange that drive patterns of legacy N discharge to surface waters. Therefore, we propose creatively integrating fine-scale field measurements of groundwater discharge and chemistry with model downscaling techniques to develop predictions of the effects of legacy N on contemporary and future surface water quality. The improved model could allow LIS management plans to set goals and develop reduction initiatives that incorporate groundwater transport of legacy N.