Department of Biosystems and Agricultural Engineering, Michigan State University, 524 S. Shaw Lane, Room 216, East Lansing, MI 48824, USA.
J Environ Manage. 2013 Oct 15;128:735-48. doi: 10.1016/j.jenvman.2013.06.019. Epub 2013 Jul 12.
Non-point source pollution from agricultural lands is a significant contributor of sediment pollution in United States lakes and streams. Therefore, quantifying the impact of individual field management strategies at the watershed-scale provides valuable information to watershed managers and conservation agencies to enhance decision-making. In this study, four methods employing some of the most cited models in field and watershed scale analysis were compared to find a practical yet accurate method for evaluating field management strategies at the watershed outlet. The models used in this study including field-scale model (the Revised Universal Soil Loss Equation 2 - RUSLE2), spatially explicit overland sediment delivery models (SEDMOD), and a watershed-scale model (Soil and Water Assessment Tool - SWAT). These models were used to develop four modeling strategies (methods) for the River Raisin watershed: Method 1) predefined field-scale subbasin and reach layers were used in SWAT model; Method 2) subbasin-scale sediment delivery ratio was employed; Method 3) results obtained from the field-scale RUSLE2 model were incorporated as point source inputs to the SWAT watershed model; and Method 4) a hybrid solution combining analyses from the RUSLE2, SEDMOD, and SWAT models. Method 4 was selected as the most accurate among the studied methods. In addition, the effectiveness of six best management practices (BMPs) in terms of the water quality improvement and associated cost were assessed. Economic analysis was performed using Method 4, and producer requested prices for BMPs were compared with prices defined by the Environmental Quality Incentives Program (EQIP). On a per unit area basis, producers requested higher prices than EQIP in four out of six BMP categories. Meanwhile, the true cost of sediment reduction at the field and watershed scales was greater than EQIP in five of six BMP categories according to producer requested prices.
农田的非点源污染是美国湖泊和溪流泥沙污染的一个重要来源。因此，量化流域尺度上单个田间管理策略的影响为流域管理者和保护机构提供了有价值的信息，以增强决策能力。在本研究中，比较了四种方法，这些方法采用了一些在田间和流域尺度分析中最常被引用的模型，以找到一种实用且准确的方法来评估流域出口处的田间管理策略。本研究中使用的模型包括田间尺度模型（修正的通用土壤流失方程 2-RUSLE2）、空间显式坡面泥沙输送模型（SEDMOD）和流域尺度模型（土壤和水评估工具-SWAT）。这些模型用于开发里弗赖因流域的四种建模策略（方法）：方法 1）在 SWAT 模型中使用预定义的田间尺度子流域和河段层；方法 2）采用流域尺度的泥沙输送比；方法 3）将从田间尺度 RUSLE2 模型获得的结果作为点源输入纳入 SWAT 流域模型；方法 4）将 RUSLE2、SEDMOD 和 SWAT 模型的分析结果相结合的混合解决方案。方法 4 被选为研究方法中最准确的方法。此外，还评估了六种最佳管理实践（BMPs）在水质改善和相关成本方面的有效性。使用方法 4 进行经济分析，并比较了生产者对 BMPs 的要求价格与环境质量激励计划（EQIP）定义的价格。在单位面积基础上，在六个 BMP 类别中有四个类别中，生产者的要价高于 EQIP。同时，根据生产者的要求价格，在五个 BMP 类别中有五个类别中，田间和流域尺度的泥沙减少的真实成本高于 EQIP。
