Watershed runoff and industrial and municipal effluents pollute streams and reservoirs. Mathematical models are needed to predict nonpoint-source pollution as affected by watershed characteristics, land use, conservation practices, chemical fertilizers, and climatic variables. Routing models are needed to determine the quality of water as it flows from nonpoint sources through streams and valleys to rivers and large reservoirs. Models are also needed to determine optimal strategies for planning land use, conservation practices, and fertilizer application to maximize agricultural production subject to water quality constraints. Three of the most important agricultural pollutants are suspended sediment, phosphorus, and nitrogen.
Sediment also transports other pollutants, like phosphorus and nitrogen.
These two elements are principally involved in lake eutrophication. The objective of this research was to develop models for use in managing large agricultural watersheds to obtain maximum agricultural production and to maintain water quality standards. Determine the optimal strategy for each subwatershed to maximize agricultural production for the entire watershed subject to water quality constraints. Generally, water-quality models are developed by adding chemical modeling components to existing runoff and sediment models because runoff and sediment provide transportation for chemicals. However, these models are not applicable to large watersheds because they have no routing mechanism.