Development of spatiotemporal waste load allocation (WLA) protocols for regulatory water quality planning and management

摘要

Water quality modeling and regulatory management guideline study was conducted of a 1499-ha (3,700 acres) watershed in the Naval Security Group Activity (NSGA) Northwest base at the Virginia/North Carolina border, USA. NSGA Northwest is a Navy Communications Facility on which the Navy, the Marines, the Coast Guard and the Noth Atlantic Treaty Organization (NATO) have facilities. The watershed has a baseline nonpoint source pollution (NPS) contributing to the Northwest River that eventually influxes to the Chesapeake Bay. Stormwater runoff discharge from the watershed influxes to the Northwest River, approximately 6.44 km (4 miles) upstream of the intake from the City of Chesapeake's potable water supply. A distributed parameter water quality model and Geographic Information System (GIS) framework was implemented to develop a spatiotemporal waste load allocation (WLA) protocols and total maximum daily load (TMDL) estimation to abate the current level of NPS pollution at the same time to preserve the quality of drinking water supply at the Northwest River. A Unix-based Arc/INFO GIS was linked to an event-based, large problem domain distributed parameter water quality model to generate runoff synthesis and subsequent transport of pollutants and sediment from the watershed. Linking such models to GIS can facilitate better data manipulation and analysis than conventional methods of manually and separately preparing data. This bilateral linkage framework resulted in a powerful, up-to-date tool that would be capable of monitoring and instantaneously visualizing the transport of any pollutant as well as effectively identifying critical areas of the NPS pollution. The framework was also used to simulate various "what if" scenarios of event-based and background load (BL) of pollutants to develop WLA and TMDL through regulatory best management practice (BMP) protocols. Results showed that the optimal BMP scenario achieved an average reduction of about 41percent in soluble and sediment-attached nitrogen and about 62percent reduction in soluble and sediment phosphorous from current NPS pollution levels.