USDA-ARS Grassland, Soil, and Water Research Laboratory, Temple, TX 76502-6712, USA.
Environ Manage. 2010 May;45(5):1164-74. doi: 10.1007/s00267-010-9458-6. Epub 2010 Mar 7.
In the United States, many state and federally funded conservation programs are required to quantify the water quality benefits resulting from their efforts. The objective of this research was to evaluate the impact of conservation practices subsidized by the Oklahoma Conservation Commission on phosphorus and sediment loads to Lake Wister. Conservation practices designed to increase vegetative cover in grazed pastures were evaluated using Landsat imagery and the Soil and Water Assessment Tool (SWAT). Several vegetative indices were derived from Landsat imagery captured before and after the implementation of conservation practices. Collectively, these indicators provided an estimate of the change in vegetative soil cover attributable to conservation practices in treated fields. Field characteristics, management, and changes in vegetative cover were used in the SWAT model to simulate sediment and phosphorus losses before and after practice implementation. Overall, these conservation practices yielded a 1.9% improvement in vegetative cover and a predicted sediment load reduction of 3.5%. Changes in phosphorus load ranged from a 1.0% improvement to a 3.5% increase, depending upon initial vegetative conditions. The use of fertilizers containing phosphorus as a conservation practice in low-productivity pastures was predicted by SWAT to increase net phosphorus losses despite any improvement in vegetative cover. This combination of vegetative cover analysis and hydrologic simulation was a useful tool for evaluating the effects of conservation practices at the basin scale and may provide guidance for the selection of conservation measures subsidized in future conservation programs.
在美国，许多由州和联邦资助的保护项目都被要求量化其努力所带来的水质效益。本研究的目的是评估俄克拉荷马州保护委员会资助的保护措施对威斯特湖磷和泥沙负荷的影响。利用陆地卫星图像和土壤和水评估工具（SWAT）评估了旨在增加放牧牧场植被覆盖率的保护措施。从实施保护措施前后获取的陆地卫星图像中得出了几个植被指数。这些指标共同提供了一个归因于处理过的田间保护措施的植被土壤覆盖变化的估计值。在 SWAT 模型中，利用田间特征、管理和植被覆盖的变化来模拟实施保护措施前后的泥沙和磷的损失。总的来说，这些保护措施使植被覆盖率提高了 1.9%，预测的泥沙负荷减少了 3.5%。磷负荷的变化范围从 1.0%的改善到 3.5%的增加，这取决于初始植被条件。尽管植被覆盖率有所提高，但 SWAT 预测，在低生产力牧场中使用含有磷的肥料作为保护措施会增加净磷损失。这种植被覆盖分析和水文模拟的结合是评估流域尺度保护措施效果的有用工具，并可为未来保护计划中资助的保护措施的选择提供指导。
