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WETLAND AND WATER RESOURCE MODELING AND ASSESSMENT: A Watershed Perspective - Chapter 12

12 Predictive Modeling of Lake Nitrogen, Phosphorus, and Sediment Concentrations Based on Land Use/Land Cover Type and Pattern Pariwate Varnakovida, Narumon Wiangwang, Joseph P. Messina, and Jiaguo Qi 12.1 INTRODUCTION In watershed management and planning, one of the major problems in lakes is the need to reduce nonpoint source pollution.1 Specific land use and land cover (LULC) types, such as “cropland” and “urban”, are associated with human activities and their physical characteristics often affect water quality.2 Land use practices and water resources are unequivocally linked. The type and the intensity of land use have a strong influence on the receiving water resource, especially in. | 12 Predictive Modeling of Lake Nitrogen Phosphorus and Sediment Concentrations Based on Land Use Land Cover Type and Pattern Pariwate Varnakovida Narumon Wiangwang Joseph P. Messina and Jiaguo Qi 12.1 INTRODUCTION In watershed management and planning one of the major problems in lakes is the need to reduce nonpoint source pollution.1 Specific land use and land cover LULC types such as cropland and urban are associated with human activities and their physical characteristics often affect water quality.2 Land use practices and water resources are unequivocally linked. The type and the intensity of land use have a strong influence on the receiving water resource especially in lakes.3 Since agricultural land is dominant in many watersheds of the upper Midwest of the United States it is considered a leading source for nonpoint source pollutants primarily sediments and nutrients. Agricultural erosion occurs when fields are cleared of vegetation to prepare for crop planting. The physical erosion potential of some soil types such as fine sandy loam may be exacerbated by nonconservation agricultural practices which may reduce the soil s chemical fertility. The angle and length of slopes on the land also influence the rate and amount of runoff and in turn influence erosion. As soil fertility declines farmers tend to increase their application of fertilizers. This intensive application of fertilizer then becomes a major source of culturally driven eutrophication in lakes and streams.4-6 Urbanization is another factor that impacts water quality. Catchment or subwatershed increases in impervious areas cause a direct impact on stream quality.7 An impervious area is any area that no longer allows rainfall to soak into the ground such as roads sidewalks rooftops and driveways. When a site is developed it loses its natural storage potential for rainfall. Consequently rain that previously infiltrated 141 2008 by Taylor Francis Group LLC 142 Wetland and Water Resource Modeling and .