The Critical Flow-Storm Approach for Nitrate TMDL Developmentin the Muddy Creek Watershed, Virginia

摘要

One of the key challenges in the TMDL development is how to define the criticalrncondition for a receiving water body. When point sources and nonpoint sources arernconsidered in an “integrated” manner, the worst-case scenario is not obviously knownrnbecause of the fact that pollutant loads come from both constant flow point sources andrnstorm-driven, time-varying nonpoint sources. The main concern of using continuousrnsimulation approach is that the use of data during specific representative hydrologicrnperiod does not necessarily cover the most “critical” condition and it is very datarnintensive. A practical, event-based Critical Flow-Storm (CFS) approach was developedrnwith application in the Nitrate TMDL Development for Muddy Creek/Dry River inrnVirginia using BASINS/HSPF. As an alternative method for TMDL development, thernCFS approach gives reasonable results and explicitly addresses the critical condition as arncombination of stream flow, magnitude of the storm event and initial watershedrncondition.