GIS Technology Group, Oak Ridge National Laboratory, PO Box 2008, MS 6237, Oak Ridge, Tennessee 37831-6237, USA, US.
Environ Manage. 2000 Dec;26(6):643-58. doi: 10.1007/s002670010122.
Land-use change, dominated by an increase in urban/impervious areas, has a significant impact on water resources. This includes impacts on nonpoint source (NPS) pollution, which is the leading cause of degraded water quality in the United States. Traditional hydrologic models focus on estimating peak discharges and NPS pollution from high-magnitude, episodic storms and successfully address short-term, local-scale surface water management issues. However, runoff from small, low-frequency storms dominates long-term hydrologic impacts, and existing hydrologic models are usually of limited use in assessing the long-term impacts of land-use change. A long-term hydrologic impact assessment (L-THIA) model has been developed using the curve number (CN) method. Long-term climatic records are used in combination with soils and land-use information to calculate average annual runoff and NPS pollution at a watershed scale. The model is linked to a geographic information system (GIS) for convenient generation and management of model input and output data, and advanced visualization of model results.The L-THIA/NPS GIS model was applied to the Little Eagle Creek (LEC) watershed near Indianapolis, Indiana, USA. Historical land-use scenarios for 1973, 1984, and 1991 were analyzed to track land-use change in the watershed and to assess impacts on annual average runoff and NPS pollution from the watershed and its five subbasins. For the entire watershed between 1973 and 1991, an 18% increase in urban or impervious areas resulted in an estimated 80% increase in annual average runoff volume and estimated increases of more than 50% in annual average loads for lead, copper, and zinc. Estimated nutrient (nitrogen and phosphorus) loads decreased by 15% mainly because of loss of agricultural areas. The L-THIA/NPS GIS model is a powerful tool for identifying environmentally sensitive areas in terms of NPS pollution potential and for evaluating alternative land use scenarios for NPS pollution management.
土地利用变化，主要表现为城市/不透水区域的增加，对水资源有重大影响。这包括对非点源（NPS）污染的影响，NPS 污染是美国水质恶化的主要原因。传统的水文模型侧重于估计高强度、间歇性暴雨的峰值排放和 NPS 污染，并成功解决了短期、局部尺度的地表水管理问题。然而，小而低频暴雨的径流量对长期水文影响占主导地位，现有的水文模型在评估土地利用变化的长期影响方面通常作用有限。本研究采用曲线数（CN）法开发了一种长期水文影响评估（L-THIA）模型。该模型结合长期气候记录、土壤和土地利用信息，计算流域尺度的平均年径流量和 NPS 污染。模型与地理信息系统（GIS）相链接，方便模型输入和输出数据的生成和管理，并对模型结果进行高级可视化。将 L-THIA/NPS GIS 模型应用于美国印第安纳州印第安纳波利斯附近的小鹰溪（LEC）流域。分析了 1973 年、1984 年和 1991 年的历史土地利用情景，以追踪流域内的土地利用变化，并评估流域及其五个子流域的年平均径流量和 NPS 污染的影响。在整个流域 1973 年至 1991 年间，城市或不透水区域增加了 18%，导致年平均径流量估计增加了 80%，铅、铜和锌的年平均负荷估计增加了 50%以上。估计的营养物（氮和磷）负荷减少了 15%，主要是因为农业面积的减少。L-THIA/NPS GIS 模型是一种强大的工具，可用于确定具有 NPS 污染潜力的环境敏感区域，并评估替代土地利用情景，以管理 NPS 污染。
