Dethier Evan N, Sartain Shannon L, Renshaw Carl E, Magilligan Francis J
Department of Earth Sciences, Dartmouth College, 6105 Hinman, Hanover, NH 03755, USA.
Department of Geography, Dartmouth College, 6107 Hinman, Hanover, NH 03755, USA.
Sci Adv. 2020 Dec 4;6(49). doi: 10.1126/sciadv.aba5939. Print 2020 Dec.
Complex hydroclimate in the United States and Canada has limited identification of possible ongoing changes in streamflow. We address this challenge by classifying 541 stations in the United States and Canada into 15 "hydro-regions," each with similar seasonal streamflow characteristics. Analysis of seasonal streamflow records at these stations from 1910 to present indicates regionally coherent changes in the frequency of extreme high- and low-flow events. Where changes are significant, these events have, on average, doubled in frequency relative to 1950 to 1969. In hydro-regions influenced by snowmelt runoff, extreme high-flow event frequency has increased despite snowpack depletion by warming winter temperatures. In drought-prone hydro-regions of the western United States and Southeast, extreme low-flow event frequency has increased, particularly during summer and fall. The magnitude and regional consistency of these hydrologic changes warrant attention by watershed stakeholders. The hydro-region framework facilitates quantification and further analyses of these changes to extreme streamflow.
美国和加拿大复杂的水文气候条件限制了对河川径流可能正在发生的变化的识别。我们通过将美国和加拿大的541个站点划分为15个“水文区域”来应对这一挑战，每个水文区域都具有相似的季节性河川径流特征。对这些站点1910年至今的季节性河川径流记录进行分析表明，极端高流量和低流量事件的发生频率存在区域一致性变化。在变化显著的地区，相对于1950年至1969年，这些事件的发生频率平均增加了一倍。在受融雪径流影响的水文区域，尽管冬季气温升高导致积雪减少，但极端高流量事件的频率仍有所增加。在美国西部和东南部易干旱的水文区域，极端低流量事件的频率有所增加，尤其是在夏季和秋季。这些水文变化的幅度和区域一致性值得流域利益相关者关注。水文区域框架有助于对这些极端河川径流变化进行量化和进一步分析。
