Department of Agricultural and Applied Economics, Virginia Tech, Blacksburg, VA, 24061, USA.
Department of Biological Systems Engineering, Virginia Tech, Blacksburg, VA, 24061, USA.
Environ Manage. 2019 Feb;63(2):173-184. doi: 10.1007/s00267-018-01133-8. Epub 2019 Jan 11.
Agricultural production is a major source of nonpoint source pollution contributing 44% of total nitrogen (N) discharged to the Chesapeake Bay. The United States Environmental Protection Agency (US EPA) established the Total Maximum Daily Load (TMDL) program to control this problem. For the Chesapeake Bay watershed, the TMDL program requires that nitrogen loadings be reduced by 25% by 2025. Climate change may affect the cost of achieving such reductions. Thus, it is necessary to develop cost-effective strategies to meet water quality goals under climate change. We investigate landscape targeting of best management practices (BMPs) based on topographic index (TI) to determine how targeting would affect costs of meeting N loading goals for Mahantango watershed, PA. We use the results from two climate models, CRCM and WRFG, and the mean of the ensemble of seven climate models (Ensemble Mean) to estimate expected climate changes and the Soil and Water Assessment Tool-Variable Source Area (SWAT-VSA) model to predict crop yields and N export. Costs of targeting and uniform placement of BMPs across the entire study area (423 ha) were compared under historical and future climate scenarios. Targeting BMP placement based on TI classes reduces costs for achieving water quality goals relative to uniform placement strategies under historical and future conditions. Compared with uniform placement, targeting methods reduce costs by 30, 34, and 27% under historical climate as estimated by the Ensemble Mean, CRCM and WRFG, respectively, and by 37, 43, and 33% under the corresponding estimates of future climate scenarios.
农业生产是非点源污染的主要来源，其向切萨皮克湾排放的总氮（N）的 44%。美国环境保护署（EPA）建立了总量最大日负荷（TMDL）计划来控制这一问题。对于切萨皮克湾流域，TMDL 计划要求到 2025 年减少 25%的氮负荷。气候变化可能会影响到实现这一减排的成本。因此，有必要制定具有成本效益的战略，以在气候变化下实现水质目标。我们根据地形指数（TI）调查最佳管理实践（BMP）的景观定位，以确定针对目标如何影响满足 Mahantango 流域 PA 的氮负荷目标的成本。我们使用两个气候模型（CRCM 和 WRFG）和七个气候模型的集合平均值（集合平均值）的结果来估计预期的气候变化，并使用土壤和水评估工具-可变源区（SWAT-VSA）模型来预测作物产量和 N 出口。在历史和未来气候情景下，比较了针对和在整个研究区域（423 公顷）均匀放置 BMP 的成本。与均匀放置相比，基于 TI 类别的 BMP 放置目标在历史和未来条件下相对于均匀放置策略可降低实现水质目标的成本。与均匀放置相比，在历史气候下，目标方法分别降低了 30%、34%和 27%的成本，而在未来气候情景的相应估计下，降低了 37%、43%和 33%的成本。
