Watershed-Scale Hydrological Modeling Methods and Applications

Pollution of surface water with harmful chemicals and eutrophication of rivers and lakes with excess nutrients are serious environmental concerns. The U.S. Environmental Protec‐ tion Agency (USEPA) estimated that 53% of the 27% assessed rivers and streams miles and 69% of the 45% assessed lakes, ponds, and reservoirs acreage in the nation are impaired (USEPA, 2010). In Mississippi, 57% of the 5% assessed rivers and streams miles are impaired (USEPA, 2010). These impairment estimates may increase when assessments of more water bodies are performed and water quality criteria are improved. The most common water pol‐ lution concerns in U.S. rivers and streams are sediment, nutrients (Phosphorus and Nitro‐ gen) and pathogens. Hydrological processes can significantly impact on the transport of water quality pollutants.