A Global Assessment of Runoff Sensitivity to Changes in Precipitation, Potential Evaporation, and Other Factors
A Global Assessment of Runoff Sensitivity to Changes in Precipitation, Potential Evaporation, and Other Factors
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DOI：
10.1002/2017wr021593
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发表时间：
2017-10-01
影响因子：
5.4
通讯作者：
Woods, Ross A.
中科院分区：
文献类型：
--
作者：
Berghuijs, Wouter R.;Larsen, Joshua R.;Woods, Ross A.
降水量（P）和潜在蒸发量（E-p）通常是研究淡水供应量变化的驱动因素，因为干旱（E-p/P）解释了地球仪平均径流量90%的空间差异。然而，目前还不清楚，如果随着时间的推移，干旱的变化也是最重要的原因，在平均径流量的时间变化，以及这种程度的重要性如何在区域上变化。我们发现，以前的全球评估，解决这些问题没有适当考虑到由于降水的变化，从而大大低估了降水对径流的影响。为了解决这一缺点，我们提供了一个改进的Budyko为基础的全球评估的相对和绝对的敏感性的降水，潜在的蒸发，和其他因素的变化，平均年径流量。径流量对潜在蒸发量变化的绝对弹性始终小于对降水量变化的弹性。全球格局表明，83%的陆地网格单元径流对降水变化最敏感，而其他因素占主导地位的其余17%。降水的这种主导作用与以往的全球评估相矛盾，以往的全球评估将干旱变化的影响视为一种比率。我们强调，旱地地区的径流对降水量变化的绝对敏感性通常很高，但在旱地地区，径流对其他因素变化的相对敏感性（例如，气候变化、CO2-植被反馈和人为改变景观）往往要高得多。然而，在全球范围内，地表水资源对降水的时间变化最为敏感。
Precipitation (P) and potential evaporation (E-p) are commonly studied drivers of changing freshwater availability, as aridity (E-p/P) explains similar to 90% of the spatial differences in mean runoff across the globe. However, it is unclear if changes in aridity over time are also the most important cause for temporal changes in mean runoff and how this degree of importance varies regionally. We show that previous global assessments that address these questions do not properly account for changes due to precipitation, and thereby strongly underestimate the effects of precipitation on runoff. To resolve this shortcoming, we provide an improved Budyko-based global assessment of the relative and absolute sensitivity of precipitation, potential evaporation, and other factors to changes in mean-annual runoff. The absolute elasticity of runoff to potential evaporation changes is always lower than the elasticity to precipitation changes. The global pattern indicates that for 83% of the land grid cells runoff is most sensitive to precipitation changes, while other factors dominate for the remaining 17%. This dominant role of precipitation contradicts previous global assessments, which considered the impacts of aridity changes as a ratio. We highlight that dryland regions generally display high absolute sensitivities of runoff to changes in precipitation, however within dryland regions the relative sensitivity of runoff to changes in other factors (e.g., changing climatic variability, CO2-vegetation feedbacks, and anthropogenic modifications to the landscape) is often far higher. Nonetheless, at the global scale, surface water resources are most sensitive to temporal changes in precipitation.