Pervasive changes in stream intermittency across the United States
Pervasive changes in stream intermittency across the United States
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DOI：
10.1088/1748-9326/ac14ec
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发表时间：
2021-08-01
影响因子：
6.7
通讯作者：
Allen, Daniel C.
中科院分区：
文献类型：
--
作者：
Zipper, Samuel C.;Hammond, John C.;Allen, Daniel C.
非常年河流是广泛存在的，对生态系统和社会至关重要，也是当前政策辩论的主题。以前对河流间歇性的大规模研究一直基于长期平均，通常使用每年聚集的数据来表征高度可变的过程。因此，人们还不能很好地了解非常年河流的水文是否、如何或为什么会发生变化。在这里，我们调查了三个间歇特征的趋势和驱动因素，这三个特征描述了整个美国大陆(CONUS)河流间歇的持续时间、时间和枯竭时期。一半的仪表在三种间歇性特征中至少有一种表现出明显的随时间变化的趋势，并且无流动持续时间的变化最为普遍(41%的仪表)。许多河流的间歇性变化很大，在研究期间，7%的量具出现了超过100天的年无流量持续时间的变化。明显的区域变化模式很明显，康涅狄格州南部普遍干旱，北部湿润。这些模式与干旱的变化相关，尽管时空变化的驱动因素在三种间歇性特征中是不同的。枯水期与流域土地利用和地形的关系最为密切。我们的结果表明，在大多数CONUS中，非常年性疾病的患病率正在增加，而“常年性”和“非常年性”的二进制分类并不能准确地反映这种变化。水管理和政策应反映当前和未来不断变化的间歇性变化的性质和不同的驱动因素。
Non-perennial streams are widespread, critical to ecosystems and society, and the subject of ongoing policy debate. Prior large-scale research on stream intermittency has been based on long-term averages, generally using annually aggregated data to characterize a highly variable process. As a result, it is not well understood if, how, or why the hydrology of non-perennial streams is changing. Here, we investigate trends and drivers of three intermittency signatures that describe the duration, timing, and dry-down period of stream intermittency across the continental United States (CONUS). Half of gages exhibited a significant trend through time in at least one of the three intermittency signatures, and changes in no-flow duration were most pervasive (41% of gages). Changes in intermittency were substantial for many streams, and 7% of gages exhibited changes in annual no-flow duration exceeding 100 days during the study period. Distinct regional patterns of change were evident, with widespread drying in southern CONUS and wetting in northern CONUS. These patterns are correlated with changes in aridity, though drivers of spatiotemporal variability were diverse across the three intermittency signatures. While the no-flow timing and duration were strongly related to climate, dry-down period was most strongly related to watershed land use and physiography. Our results indicate that non-perennial conditions are increasing in prevalence over much of CONUS and binary classifications of 'perennial' and 'non-perennial' are not an accurate reflection of this change. Water management and policy should reflect the changing nature and diverse drivers of changing intermittency both today and in the future.