Paleohydrological context for recent floods and droughts in the Fraser River Basin, British Columbia, Canada
Paleohydrological context for recent floods and droughts in the Fraser River Basin, British Columbia, Canada
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DOI：
10.1088/1748-9326/ac3daf
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发表时间：
2021-11
影响因子：
6.7
通讯作者：
Becky L. Brice;Bethany L Coulthard;Inga K. Homfeld;L. Dye;K. Anchukaitis
中科院分区：
文献类型：
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作者：
Becky L. Brice;Bethany L Coulthard;Inga K. Homfeld;L. Dye;K. Anchukaitis
最近不列颠哥伦比亚省弗雷泽河流域 (FRB) 的洪水和干旱加剧，产生了深远的文化、生态和经济影响，预计人为气候变化将进一步加剧这种影响。部分原因是仪器径流记录较短，人们对这一北美主要流域极端水文气候的长期平稳性仍知之甚少，这突出表明需要使用高分辨率古环境代理来了解过去的水流。在这里，我们使用树木年轮代理记录网络来开发 11 个子流域规模、互补的洪水和干旱季节重建，这在此类重建中尚属首次。重建明确针对每个流域内与管理相关的洪水和干旱季节，并同时进行检查，以提供对整个 FRB 极端事件的扩展评估，对水资源管理产生直接影响。我们发现，过去的高洪水季节流量比单独观测记录期间的流量更大，并且连续发生的年份更多。与最近的干旱时期相比，20世纪初干旱季节的低流量在持续时间和强度上都特别严重。我们的弗雷泽次流域规模重建为人为强迫之前的自然洪水和干旱变化提供了长期基准。这些重建表明，当前管理所依据的仪器径流记录可能低估了快速射电暴中极端季节性流量的全部自然强度、持续时间和频率，以及未来人为强迫事件的潜在严重性。
The recent intensification of floods and droughts in the Fraser River Basin (FRB) of British Columbia has had profound cultural, ecological, and economic impacts that are expected to be exacerbated further by anthropogenic climate change. In part due to short instrumental runoff records, the long-term stationarity of hydroclimatic extremes in this major North American watershed remains poorly understood, highlighting the need to use high-resolution paleoenvironmental proxies to inform on past streamflow. Here we use a network of tree-ring proxy records to develop 11 subbasin-scale, complementary flood- and drought-season reconstructions, the first of their kind. The reconstructions explicitly target management-relevant flood and drought seasons within each basin, and are examined in tandem to provide an expanded assessment of extreme events across the FRB with immediate implications for water management. We find that past high flood-season flows have been of greater magnitude and occurred in more consecutive years than during the observational record alone. Early 20th century low flows in the drought season were especially severe in both duration and magnitude in some subbasins relative to recent dry periods. Our Fraser subbasin-scale reconstructions provide long-term benchmarks for the natural flood and drought variability prior to anthropogenic forcing. These reconstructions demonstrate that the instrumental streamflow records upon which current management is based likely underestimate the full natural magnitude, duration, and frequency of extreme seasonal flows in the FRB, as well as the potential severity of future anthropogenically forced events.