Graduate school of life and environmental sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba City, Ibaraki 305-8577, Japan.
Faculty of life and environmental sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba City, Ibaraki 305-8577, Japan.
Sci Total Environ. 2018 Mar;616-617:1-16. doi: 10.1016/j.scitotenv.2017.10.290. Epub 2017 Nov 3.
Soil erosion can be reduced through the strategic selection and placement of best management practices (BMPs) in critical source areas (CSAs). In the present study, the Soil Water Assessment Tool (SWAT) model was used to identify CSAs and investigate the effectiveness of different BMPs in reducing sediment yield in the Joumine watershed, an agricultural river catchment located in northern Tunisia. A cost-benefit analysis (CBA) was used to evaluate the cost-effectiveness of different BMP scenarios. The objective of the present study was to determine the most cost-effective management scenario for controlling sediment yield. The model performance for the simulation of streamflow and sediment yield at the outlet of the Joumine watershed was good and satisfactory, respectively. The model indicated that most of the sediment was originated from the cultivated upland area. About 34% of the catchment area consisted of CSAs that were affected by high to very high soil erosion risk (sediment yield >10t/ha/year). Contour ridges were found to be the most effective individual BMP in terms of sediment yield reduction. At the watershed level, implementing contour ridges in the CSAs reduced sediment yield by 59%. Combinations of BMP scenarios were more cost-effective than the contour ridges alone. Combining buffer strips (5-m width) with other BMPs depending on land slope (> 20% slope: conversion to olive orchards; 10-20% slope: contour ridges; 5-10% slope: grass strip cropping) was the most effective approach in terms of sediment yield reduction and economic benefits. This approach reduced sediment yield by 61.84% with a benefit/cost ratio of 1.61. Compared with the cost of dredging, BMPs were more cost-effective for reducing sediment loads to the Joumine reservoir, located downstream of the catchment. Our findings may contribute to ensure the sustainability of future conservation programs in Tunisian regions.
通过在关键源区（CSAs）战略性地选择和布置最佳管理措施（BMPs），可以减少土壤侵蚀。在本研究中，使用土壤水评估工具（SWAT）模型来识别 CSA，并研究不同 BMP 在减少突尼斯北部 Joumine 流域农业河流集水区泥沙产量方面的有效性。使用成本效益分析（CBA）来评估不同 BMP 情景的成本效益。本研究的目的是确定控制泥沙产量的最具成本效益的管理方案。该模型在模拟 Joumine 流域出口处的径流量和泥沙产量方面表现良好，分别为满意和满意。该模型表明，大部分泥沙来源于耕地。约 34%的集水区属于 CSA，这些 CSA 受到高到极高的土壤侵蚀风险（泥沙产量>10t/ha/年）的影响。等高线垄被认为是减少泥沙产量最有效的单项 BMP。在流域层面上，在 CSA 中实施等高线垄可减少 59%的泥沙产量。BMP 方案的组合比单独的等高线垄更具成本效益。根据土地坡度（>20%坡度：转换为橄榄园；10-20%坡度：等高线垄；5-10%坡度：草带种植），将缓冲带（5 米宽）与其他 BMP 结合使用，是减少泥沙产量和经济效益的最有效方法。这种方法可减少 61.84%的泥沙产量，效益/成本比为 1.61。与疏浚成本相比，BMP 更能有效地减少泥沙负荷到 Joumine 水库，位于集水区下游。我们的研究结果可能有助于确保突尼斯地区未来保护计划的可持续性。
