Department of Geosciences, Middle Tennessee State University, TN, USA.
Department of Geosciences, Middle Tennessee State University, TN, USA.
J Environ Manage. 2024 Dec;371:123278. doi: 10.1016/j.jenvman.2024.123278. Epub 2024 Nov 11.
Conservation practices have been recognized as an important mitigation tool to reduce soil loss and sediment transport from agricultural fields. Multiple conservation structures and farming practices have been proposed to target erosional processes with varying results of sediment trapping efficiency. The quantification of their performance at the watershed scale when multiple integrated and spatiotemporal varying processes occur, remains a challenge. In this study, the impact of conservation practices on erosion from sheet/rill and ephemeral gully sources at field and watershed scales were investigated on a USDA Conservation Effects Assessment Project (CEAP) watershed draining into the Chesapeake Bay. Three periods were identified: 1990-2000, 2010-2020, and 2000-2010 representing before, after, and a transition period of conservation practices implementation, respectively. Ephemeral gullies and conservation practices were characterized at raster grid scale and evaluated at field and watershed scales. The AnnAGNPS watershed pollution model was used to quantify sediment loads before and after actual conservation practices were implemented. Simulation results indicated a potential reduction from implemented conservation practices of approximately 10% from ephemeral gully sources and 30% from sheet/rill sources in annual average sediment loads, or by 60% overall when comparing annual averages expressed as sediment concentration. Analysis of sediment loads indicates that the implemented practices are less effective in deterring sediments from ephemeral gully sources. Two significant precipitation events with an estimated recurrence interval greater than 250 years were estimated to be responsible for adding 25% (151.73 Mg) to the 11-year annual average sediment load prompting the need for future research on the impact of extreme events on soil loss. Using customized soil erosion prediction technology designed for the quantification of diverse source and sink of sediment is a valuable resource for stakeholders seeking to develop erosion mitigation strategies.
保护实践已被公认为减少农田土壤流失和泥沙输移的重要缓解工具。已经提出了多种保护结构和耕作措施来针对侵蚀过程，其泥沙截留效率的结果也有所不同。当多个综合和时空变化的过程发生时，在流域尺度上量化它们的性能仍然是一个挑战。在这项研究中，在美国农业部保护效果评估项目 (CEAP) 流域中，对从片流/细沟和短暂性冲沟源到田间和流域尺度的侵蚀进行了研究，该流域排入切萨皮克湾。确定了三个时期：1990-2000 年、2010-2020 年和 2000-2010 年，分别代表保护措施实施之前、之后和过渡时期。短暂性冲沟和保护措施在栅格网格尺度上进行了特征描述，并在田间和流域尺度上进行了评估。使用 AnnAGNPS 流域污染模型来量化实际保护措施实施前后的泥沙负荷。模拟结果表明，从实施的保护措施中，每年平均泥沙负荷中，短暂性冲沟源减少了约 10%，片流/细沟源减少了 30%；如果将每年的平均泥沙浓度作为比较，那么总体减少了 60%。泥沙负荷分析表明，实施的措施在阻止短暂性冲沟源泥沙方面效果较差。估计两次具有大于 250 年重现期的重大降水事件导致每年平均泥沙负荷增加了 25%（151.73 Mg），这促使人们需要对极端事件对土壤流失的影响进行未来研究。使用为量化不同泥沙源和汇而设计的定制土壤侵蚀预测技术，是利益相关者寻求制定侵蚀缓解策略的宝贵资源。
