Topographically delineated catchments are the common spatial unit to connect human activities and climate change with their consequences for water availability as a prerequisite for sustainable water management. However, inter-catchment groundwater flow and limited connectivity within the catchment results in effective catchment areas different from those suggested by surface topography. Here, we introduce the notion of effective catchment area quantified through an effective catchment index (ECI), derived from observed streamflow, precipitation and actual evapotranspiration estimates, to understand the prevalence and significance of substantial differences between topographic and effective catchment areas in a global dataset. We evaluate our ECI analysis by comparing it to hydraulic head simulations of a global groundwater flow model and to the Budyko framework. We find that one in three studied catchments exhibit an effective catchment area either larger than double or smaller...

中文翻译：

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流域的水文有效面积是多少？

划定轮廓的集水区是将人类活动和气候变化及其对水资源可用性的影响联系起来的常见空间单位，这是可持续水资源管理的前提。然而，集水区之间的地下水流和集水区内有限的连通性导致有效集水区不同于地表地形所建议的面积。在这里，我们介绍通过有效集水指数（ECI）量化的有效集水区的概念，该指数是从观测到的水流，降水和实际蒸散量估算得出的，以了解全球数据集中的地形和有效集水区之间存在实质性差异的普遍性和重要性。通过与全球地下水流模型的水头模拟和Budyko框架进行比较，我们评估了ECI分析。我们发现，研究的流域中有三分之一表现出的有效流域面积大于两倍或更小。