Watershed-Based Modeling with AGNPS for Storm Water Management

Abstract

A strategy for developing sediment transport information for storm water planning and management is described. The strategy links location-based and intensity-based development scenarios with potential water quality impacts to a stream system and at a watershed outlet and (1) is based on sediment transport calculations; (2) develops information that supports community decision making; and (3) is consistent with the Environmental Protection Agency (EPA) Phase II storm water requirements and other guidance on watershed management. The strategy is an effort to incorporate the impact of site-specific watershed characteristics into storm water ordinances. This effort was undertaken to provide a rational means for a community to differentiate the sediment contributions from alternative scenarios at alternative locations. One of the options available with differentiation information is the ability to negotiate and approve pollutant “trades” between different development practices in different locations such that water quality standards are maintained throughout the trading area. The Agricultural Non-Point Source (AGNPS) pollutant modeling system was used in the community of Ashland, Mo. to provide an example of the methodology.