Variability of stream extents controlled by flow regime and network hydraulic scaling
Variability of stream extents controlled by flow regime and network hydraulic scaling
复制标题
由流态和网络水力缩放控制的河流范围的变化
作者：
D. Lapides;Christine D. Leclerc;H. Moidu;D. Dralle;W. Hahm
河流网络随着时间的推移而扩展和收缩，影响化学品出口、水生生物栖息地和水质。尽管最近的进展改进了基于汇水口流量(Q)对湿润河网(L)范围的预测，但对L时间变异性的控制仍然知之甚少，也没有量化。在这里，我们开发了一个定量的概念框架，以探索水流状况和河网水力比例因子如何共同决定L的相对时间变异性(这里表示为湿润河道总排水密度)。网络水力标度决定了L因Q的变化而变化的程度，而流态则描述了Q如何随时间变化。我们编制了同址动态河段图和流量的数据集，以使用所提出的框架来分析所有全球可用的经验数据。我们发现，尽管L的变化相对于Q的变化是普遍的抑制的(即，径流在时间上的变化比网络范围的变化相对更大)，但这种关系是弹性的，这意味着对于给定的Q变化的增加，水源集水区的L的变化的增加将大于成比例的增加。因此，在预期的气候转向更不稳定的降水的情况下，可以预期源头水系范围的相对变化的增加甚至比流量本身的相对变化更大。将L-Q关系推算出的河网范围与美国地质调查局地形图上的蓝线进行比较，结果表明，蓝线网络普遍低估了湿润河网。
Stream networks expand and contract through time, impacting chemical export, aquatic habitat, and water quality. Although recent advances improve prediction of the extent of the wetted channel network (L) based on discharge at the catchment outlet (Q), controls on the temporal variability of L remain poorly understood and unquantified. Here we develop a quantitative, conceptual framework to explore how flow regime and stream network hydraulic scaling factors co‐determine the relative temporal variability in L (denoted here as the total wetted channel drainage density). Network hydraulic scaling determines how much L changes for a change in Q, while the flow regime describes how Q changes in time. We compiled datasets of co‐located dynamic stream extent mapping and discharge to analyze all globally available empirical data using the presented framework. We found that although variability in L is universally damped relative to variability in Q (i.e., streamflow is relatively more variable in time than network extent), the relationship is elastic, meaning that for a given increase in the variability in Q, headwater catchments will experience greater‐than‐proportional increases in the variability of L. Thus, under anticipated climatic shifts towards more volatile precipitation, relative variability in headwater stream network extents can be expected to increase even more than the relative variability of discharge itself. Comparison between network extents inferred from the L‐Q relationship and blue lines on USGS topographic maps shows widespread underestimation of the wetted channel network by the blue line network.
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影响因子：
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通讯作者：
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