Urbanization in Arid Central Arizona Watersheds Results in Decreased Stream Flashiness
Urbanization in Arid Central Arizona Watersheds Results in Decreased Stream Flashiness
复制标题
干旱的亚利桑那州中部流域的城市化导致溪流闪度降低
作者：
L. McPhillips;S. Earl;R. Hale;N. Grimm
人们普遍认为，城市化会导致河流水文发生巨大变化，例如高峰流量增加和洪水泛滥。然而，这还没有得到明确的测试干旱地区，其特点是这些非常相同的水文特性。我们分析了美国亚利桑那州中部19个流域的径流记录，以确定如何水文特征随城市发展而变化。使用线性混合效应模型，其中考虑了不透水性沿着与其他流域特性，我们评估了对径流制度指标计算每日和每日以下流量数据的影响。我们发现，闪光，变异系数，零流量天，和水文上升和下降率下降的不透性的程度，在以前的研究中观察到的相反的模式，主要是在潮湿地区。工程保留盆地是这种观察的一种解释，尽管干旱天气流的新城市来源也可能发挥作用。我们还发现这些水文指标与平均面积加权流量，流域面积和年降水量之间存在很强的关系。像在潮湿的系统中，我们确实观察到更多的高流量事件相比，非城市沙漠流在城市沙漠流。然而，这只是在较低的洪水阈值;随着城市的发展，较大的洪水并没有增加。总体而言，城市流综合征表现在这个干旱的系统不同：城市化增加了水的保留，并导致流生态系统中的流量变化较小。
There is broad consensus that urbanization results in dramatic changes in stream hydrology, such as higher peak flows and greater flashiness. However, this has not been definitively tested for aridlands, which are characterized by these very same hydrograph properties. We analyzed streamflow records from 19 watersheds of central Arizona, USA, to determine how hydrograph characteristics varied with urban development. Using linear mixed effects models, which factored in imperviousness along with other watershed characteristics, we evaluated influences on streamflow regime metrics calculated from daily and subdaily flow data. We found that flashiness, coefficient of variation, zero‐flow days, and hydrograph rise and fall rates decreased with extent of imperviousness—the opposite pattern to that observed in previous studies primarily in humid regions. Engineered retention basins are one explanation for this observation though novel urban sources of dry weather flows are likely also playing a role. We also found strong relationships between these hydrologic metrics and mean area‐weighted discharge, watershed area, and annual precipitation. Like in humid systems, we did observe more high flow events in the urban desert streams compared to nonurban desert streams. However, this was only at the lower flood threshold; there was no increase in larger floods with urban development. Overall, the urban stream syndrome manifests differently in this arid system: Urbanization increases water retention and leads to less variable flows in stream ecosystems.