FutureWater, Costerweg 1V, 6702 AA Wageningen, The Netherlands.
J Environ Manage. 2012 Nov 30;111:187-94. doi: 10.1016/j.jenvman.2012.07.022. Epub 2012 Aug 21.
Upstream soil and water conservation measures in catchments can have positive impact both upstream in terms of less erosion and higher crop yields, but also downstream by less sediment flow into reservoirs and increased groundwater recharge. Green Water Credits (GWC) schemes are being developed to encourage upstream farmers to invest in soil and water conservation practices which will positively effect upstream and downstream water availability. Quantitative information on water and sediment fluxes is crucial as a basis for such financial schemes. A pilot design project in the large and strategically important Upper-Tana Basin in Kenya has the objective to develop a methodological framework for this purpose. The essence of the methodology is the integration and use of a collection of public domain tools and datasets: the so-called Green water and Blue water Assessment Toolkit (GBAT). This toolkit was applied in order to study different options to implement GWC in agricultural rainfed land for the pilot study. Impact of vegetative contour strips, mulching, and tied ridges were determined for: (i) three upstream key indicators: soil loss, crop transpiration and soil evaporation, and (ii) two downstream indicators: sediment inflow in reservoirs and groundwater recharge. All effects were compared with a baseline scenario of average conditions. Thus, not only actual land management was considered but also potential benefits of changed land use practices. Results of the simulations indicate that especially applying contour strips or tied ridges significantly reduces soil losses and increases groundwater recharge in the catchment. The model was used to build spatial expressions of the proposed management practices in order to assess their effectiveness. The developed procedure allows exploring the effects of soil conservation measures in a catchment to support the implementation of GWC.
集水区上游的水土保持措施可以在减少侵蚀和提高作物产量方面产生积极影响，也可以通过减少泥沙流入水库和增加地下水补给来改善下游的情况。正在制定绿色水资源信用（GWC）计划，以鼓励上游农民投资于水土保持实践，从而对上下游的水资源供应产生积极影响。有关水和泥沙通量的定量信息是此类财务计划的基础，至关重要。肯尼亚大型且具有战略重要性的上塔纳流域的一个试点设计项目旨在为此目的制定一个方法论框架。该方法的核心是整合和利用一系列公共领域的工具和数据集：即所谓的绿色水资源和蓝色水资源评估工具包（GBAT）。该工具包用于研究在农业雨养土地中实施 GWC 的不同选择，作为试点研究的一部分。确定了植被等高条带、覆盖物和垄作的以下影响：(i) 三个上游关键指标：土壤流失、作物蒸腾和土壤蒸发，以及 (ii) 两个下游指标：水库泥沙流入和地下水补给。所有影响都与平均条件的基准情景进行了比较。因此，不仅考虑了实际的土地管理，还考虑了土地利用方式改变带来的潜在效益。模拟结果表明，特别是应用等高条带或垄作可以显著减少集水区的土壤流失并增加地下水补给。该模型用于构建拟议管理实践的空间表达，以评估其效果。所开发的程序允许探索集水区中水土保持措施的效果，以支持 GWC 的实施。
