Nonpoint nông nghiệp ô nhiễm nguồn tài nguyên nước do thuốc trừ sâu, phân bón, chất thải động vật, và xói mòn đất là một vấn đề lớn trong nhiều của Đại Laurentian Lakes lưu vực sông, nằm giữa Hoa Kỳ và Canada. Điểm nhiễm bẩn nguồn, chẳng hạn như tràn thoát nước kết hợp (CSO), cũng có thêm các chất thải dòng chảy. Xói mòn đất và trầm tích làm giảm độ phì nhiêu của đất và năng suất nông nghiệp, giảm tuổi thọ của hồ chứa và hồ, và gia tăng lũ lụt và chi phí cho các. | 9 Spatially Distributed Watershed Model of Water and Materials Runoff Thomas E. Croley II and Chansheng He INTRODUCTION Agricultural nonpoint source contamination of water resources by pesticides fertilizers animal wastes and soil erosion is a major problem in much of the Laurentian Great Lakes Basin located between the United States and Canada. Point source contaminations such as combined sewerage overflows CSOs also add wastes to water flows. Soil erosion and sedimentation reduce soil fertility and agricultural productivity decrease the service life of reservoirs and lakes and increase flooding and costs for dredging harbors and treating wastewater. Improper management of fertilizers pesticides and animal and human wastes can cause increased levels of nitrogen phosphorus and toxic substances in both surface water and groundwater. Sediment waste pesticide and nutrient loadings to surface and subsurface waters can result in oxygen depletion and eutrophication in receiving lakes as well as secondary impacts such as harmful algal blooms and beach closings due to viral and bacterial and or toxin delivery to affected sites. The . Environmental Protection Agency EPA has identified contaminated sediments urban runoff and storm sewers and agriculture as the primary sources of pollutants causing impairment of Great Lakes shoreline waters USEPA 2002 . Prediction of various ecological system variables or consequences such as beach closings as well as effective management of pollution at the watershed scale require estimation of both point and nonpoint source material transport through a watershed by hydrological processes. However currently there are no integrated fine-resolution spatially distributed physically based watershedscale hydrological water quality models available to evaluate movement of materials sediments animal and human wastes agricultural chemicals nutrients etc. in both surface and subsurface waters in the Great Lakes watersheds. The Great Lakes .
