Department of Biosystems and Agricultural Engineering, Michigan State University, 524 S. Shaw Lane, Room 216, East Lansing, MI 48824, USA.
Department of Biosystems and Agricultural Engineering, Michigan State University, 524 S. Shaw Lane, Room 216, East Lansing, MI 48824, USA.
J Environ Manage. 2017 May 1;192:184-196. doi: 10.1016/j.jenvman.2017.01.059. Epub 2017 Feb 2.
Freshwater resources are vital for human and natural systems. However, anthropogenic activities, such as agricultural practices, have led to the degradation of the quality of these limited resources through pollutant loading. Agricultural Best Management Practices (BMPs), such as wetlands, are recommended as a valuable solution for pollutant removal. However, evaluation of their long-term impacts is difficult and requires modeling since performing in-situ monitoring is expensive and not feasible at the watershed scale. In this study, the impact of natural wetland implementation on total phosphorus reduction was evaluated both at the subwatershed and watershed levels. The study area is the Saginaw River Watershed, which is largest watershed in Michigan. The phosphorus reduction performances of four different wetland sizes (2, 4, 6, and 8 ha) were evaluated within this study area by implementing one wetland at a time in areas identified to have the highest potential for wetland restoration. The subwatershed level phosphorus loads were obtained from a calibrated Soil and Water Assessment Tool (SWAT) model. These loads were then incorporated into a wetland model (System for Urban Stormwater Treatment and Analysis IntegratioN-SUSTAIN) to evaluate phosphorus reduction at the subwatershed level and then the SWAT model was again used to route phosphorus transport to the watershed outlet. Statistical analyses were performed to evaluate the spatial impact of wetland size and placement on phosphorus reduction. Overall, the performance of 2 ha wetlands in total phosphorus reduction was significantly lower than the larger sizes at both the subwatershed and watershed levels. Regarding wetland implementation sites, wetlands located in headwaters and downstream had significantly higher phosphorus reduction than the ones located in the middle of the watershed. More specifically, wetlands implemented at distances ranging from 200 to 250 km and 50-100 km from the outlet had the highest impact on phosphorus reduction at the subwatershed and watershed levels, respectively. A multi criteria decision making (MCDM) method named VIKOR was successfully executed to identify the most suitable wetland size and location for each subwatershed considering the phosphorus reduction and economic cost associated with wetland implementation. The methods introduced in this study can be easily applied to other watersheds for selection and placement of wetlands while considering environmental benefits and economic costs.
淡水资源对人类和自然系统至关重要。然而，农业活动等人为活动通过污染物负荷导致这些有限资源的质量下降。湿地等农业最佳管理实践 (BMP) 被推荐为去除污染物的一种有价值的解决方案。然而，由于原位监测成本高昂且在流域尺度上不可行，因此评估其长期影响具有挑战性且需要建模。在这项研究中，评估了在子流域和流域层面实施自然湿地对总磷减少的影响。研究区域是苏必利尔河流域，这是密歇根州最大的流域。本研究在该研究区域内一次实施一个湿地，评估了四个不同湿地规模（2、4、6 和 8 公顷）对总磷减少的影响，这些湿地位于被确定为具有最高湿地恢复潜力的区域。子流域水平的磷负荷通过校准的土壤和水评估工具 (SWAT) 模型获得。然后将这些负荷纳入湿地模型（城市雨水处理和分析综合系统-SUSTAIN）中，以评估子流域水平的磷减少，然后再次使用 SWAT 模型将磷输送到流域出口。进行了统计分析，以评估湿地规模和位置对磷减少的空间影响。总体而言，2 公顷湿地在总磷减少方面的性能明显低于较大规模的湿地，无论是在子流域还是流域水平。关于湿地实施地点，位于源头和下游的湿地在磷减少方面明显高于位于流域中部的湿地。更具体地说，距离出口 200 至 250 公里和 50-100 公里范围内实施的湿地分别对子流域和流域水平的磷减少影响最大。成功执行了一种名为 VIKOR 的多标准决策制定 (MCDM) 方法，以根据磷减少和与湿地实施相关的经济成本，为每个子流域确定最合适的湿地规模和位置。本研究中介绍的方法可以轻松应用于其他流域，以在考虑环境效益和经济成本的情况下选择和放置湿地。
