ABSTRACT In humid regions, surface runoff is often generated by saturation-excess runoff mechanisms from relatively small variable source areas (VSAs). However, the majority of the current hydrologic models are based on infiltration-excess mechanisms. In this study, the AGricultural Non-Point Source Pollution (AGNPS) model was used to integrate the VSA concept using topographic wetness index (TWI). Both the original and AGNPS-VSA models were evaluated for a small agricultural field in Ontario, Canada. The results indicate that the AGNPS-VSA model performed better than original model. The AGNPS-VSA model predicted that only the saturated portion of the field with higher TWI values produced runoff, whereas the original AGNPS model showed uniform hydrologic response from the entire field. The results of this study are important for accurately mapping the locations of VSAs. This new model could be a powerful tool in identifying critical source areas for applying targeted best management practices to minimize pollutant loads to receiving waters.

中文翻译：

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使用 AGNPS-VSA 模型绘制径流生成区

摘要 在潮湿地区，地表径流通常是由来自相对较小的可变源区 (VSA) 的饱和过量径流机制产生的。然而，当前的大多数水文模型都是基于渗透过量机制的。在本研究中，农业非点源污染 (AGNPS) 模型用于使用地形湿度指数 (TWI) 整合 VSA 概念。原始模型和 AGNPS-VSA 模型都针对加拿大安大略省的一个小农田进行了评估。结果表明，AGNPS-VSA 模型的性能优于原始模型。AGNPS-VSA 模型预测只有具有较高 TWI 值的田地的饱和部分产生径流，而原始 AGNPS 模型显示整个田地的水文响应一致。这项研究的结果对于准确绘制 VSA 的位置很重要。这种新模型可以成为确定关键源区的有力工具，以应用有针对性的最佳管理实践，以尽量减少受纳水域的污染物负荷。