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首页> 外文期刊>Journal of Hydrology >Combining sediment source tracing techniques with traditional monitoring to assess the impact of improved land management on catchment sediment yields
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Combining sediment source tracing techniques with traditional monitoring to assess the impact of improved land management on catchment sediment yields

机译：将泥沙源追踪技术与传统监测相结合，以评估改善土地管理对流域泥沙产量的影响

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This paper aims to demonstrate the potential value of combining sediment source tracing techniques with traditional monitoring approaches, when documenting the impact of improved land management on catchment sediment yields. It reports the results of an investigation undertaken in a small (1.19 km(2)) agricultural catchment in southern Brazil, which was monitored before and after the implementation of improved Land management practices. Attention focussed on 50 storm events that occurred between May 2002 and March 2006 and which reflected the behaviour of the catchment during the pre-change, transition and post-change periods. Improved [and management, involving minimum-till cultivation and the maintenance of good crop cover, was introduced in early 2003. The traditional monitoring provided a basis for evaluating the changes in storm runoff volume, storm hydrograph peak and storm-period sediment Load and mean suspended sediment concentration. The results indicate that both storm runoff volumes and peak flows associated with a given amount of rainfall provided evidence of a significant decrease after the introduction of improved land management. Storm-period sediment loads showed a similar reduction, with a reduction by as much as 80% for low magnitude events and of ca. 40% for events of intermediate magnitude. However, there was no significant change in mean suspended sediment concentrations, indicating that the reductions in sediment load were primarily the result of the reduced storm runoff volume. Sediment source fingerprinting was used to explore the changes in the relative and absolute contributions to the storm sediment loads from the three key sources, namely the surface of the fields under crops, the unpaved roads and the stream channels. A comparison of the load-weighted mean contributions for the pre- and post-treatment periods indicated that the contribution from the field surfaces and unpaved roads decreased from 63% and 36% to 54% and 24%, respectively, whereas the contribution from the stream channels increased from ca. 2% to 22%. By relating the absolute amounts of sediment mobilised from each individual source,group to variables representing the runoff and precipitation associated with the events, it was possible to identify changes in the response of the individual sediment sources to the changes in land management that occurred within the catchment. Sediment mobilisation from the stream channel during individual events increased substantially over the whole range of flows after the introduction of improved land management in the study catchment, whereas the amounts of sediment mobilised from the surfaces of the fields and the unpaved roads showed a significant decrease during events of low and intermediate magnitude. The short monitoring period associated with the study, coupled with inter-annual variations in rainfall, necessarily limit the scope and rigour of the study reported, but it is seen to provide a useful demonstration of how the coupling of sediment source tracing with more traditional monitoring techniques can provide an improved understanding of the impact of improved management practices on the sediment response of a catchment, as well as important information to inform the design and implementation of effective sediment management and control measures.
机译：本文旨在证明在记录改进的土地管理对流域沉积物产量的影响时，将沉积物源追踪技术与传统监测方法相结合的潜在价值。它报告了在巴西南部的一个小型（1.19 km（2））农业流域进行的调查结果，在实施改进的土地管理规范之前和之后均进行了监视。注意力集中在2002年5月至2006年3月之间发生的50次风暴事件上，这些事件反映了集水区在变更前，过渡和变更后期间的行为。 2003年初引入了改进的[和管理，包括最低耕作和维持良好的作物覆盖。传统的监测为评估暴雨径流量，暴雨水位图峰值和暴雨期沉积物的变化提供了基础。悬浮沉积物浓度。结果表明，在引入改进的土地管理后，与一定降雨量相关的风暴径流量和峰值流量都提供了明显减少的证据。暴风雨时期的泥沙负荷也显示出类似的减少，对于低强度事件，大约减少了80％。中度事件占40％。但是，平均悬浮沉积物浓度没有明显变化，表明沉积物负荷的减少主要是风暴径流量减少的结果。泥沙源指纹图谱被用于研究来自三个关键源（即农作物地表，未铺砌的道路和河道）三个对风暴泥沙负荷的相对和绝对贡献的变化。对治疗前后的负荷加权平均贡献的比较表明，田间地面和未铺砌道路的贡献分别从63％和36％降低到54％和24％，而流通道从约增加。 2％至22％。通过将从每个单独来源，组中调集的沉积物的绝对量与代表与事件相关的径流和降水的变量相关联，可以确定单个沉积物源对土地内部发生的土地管理变化的响应变化。集水。在研究流域引入改进的土地管理后，在单个事件中，河道中的泥沙迁移量在整个流量范围内显着增加，而在田间和未铺砌的道路上，泥沙迁移量显着减少。中低级事件。与该研究有关的监测期短，加上降雨的年际变化，必然会限制所报告研究的范围和严格性，但可以提供一个有用的例证，说明如何将泥沙源追踪与更传统的监测结合起来这些技术可以更好地了解改进的管理实践对集水区泥沙响应的影响，以及可以为有效的泥沙管理和控制措施的设计和实施提供重要信息的信息。

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