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首页> 外文期刊>Journal of Hydrology >Is worst-case scenario streamflow drought underestimated in British Columbia? A multi-century perspective for the south coast, derived from tree-rings
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Is worst-case scenario streamflow drought underestimated in British Columbia? A multi-century perspective for the south coast, derived from tree-rings

机译：在不列颠哥伦比亚省，最坏情况下的河流径流干旱是否被低估了？树环派生出的对南海岸的跨世纪视角

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摘要

Recent streamflow droughts in south coastal British Columbia have had major socioeconomic and ecological impacts. Increasing drought severity under projected climate change poses serious water management challenges, particularly in the small coastal watersheds that serve as primary water sources for most communities in the region. A 332-year dendrohydrological record of regionalized mean summer streamflow for four watersheds is analyzed to place recent drought magnitudes in a long-term perspective. We present a novel approach for optimizing tree-ring based reconstructions in small watersheds in temperate environments, combining winter snow depth and summer drought sensitive proxies as model predictors. The reconstruction model, estimated by regression of observed flows on Tsuga mertensiana ring-width variables and a tree-ring derived paleorecord of the Palmer Drought Severity Index, explains 64% of the regionalized streamflow variance. The model is particularly accurate at estimating lowest flow events, and provides the strongest annually resolved paleohydrological record in British Columbia. The extended record suggests that since 1658 sixteen natural droughts have occurred that were more extreme than any within the instrumental period. Flow-duration curves show more severe worst-case scenario droughts and a higher probability of those droughts in the long-term reconstruction than in the hydrometric data. Such curves also highlight the value of dendrohydrology for probabilistic drought assessment. Our results suggest current water management strategies based on worst-case scenarios from historical gauge data likely underestimate the potential magnitudes of natural droughts. If the low-flow magnitudes anticipated under climate change co-occur with lowest possible natural flows, streamflow drought severities in small watersheds in south coastal British Columbia could exceed any of those experienced in the past similar to 350 years. Crown Copyright (C) 2016 Published by Elsevier B.V. All rights reserved.
机译：不列颠哥伦比亚省南部沿海地区最近的河水干旱对社会经济和生态产生了重大影响。在预计的气候变化下干旱严重程度的提高给水资源管理带来了严峻的挑战，特别是在沿海小流域，该流域是该地区大多数社区的主要水源。分析了四个流域的区域平均夏季水流的332年水文记录，从长远角度分析了最近的干旱程度。我们提出了一种在温带环境中的小流域优化基于树轮的重建的新颖方法，将冬季雪深和夏季干旱敏感的代理结合在一起作为模型预测指标。重建模型是通过对观察到的美洲杉圆环变宽的流量回归分析和帕尔默干旱严重度指数的树轮古记录进行估算的，该模型解释了64％的区域性水流变化。该模型在估计最低流量事件时特别准确，并且提供了不列颠哥伦比亚省最强的年度解析古水文学记录。扩展的记录表明，自1658年以来发生了16次自然干旱，其干旱程度超过了工具时期。流量持续时间曲线显示，与水文数据相比，在长期重建中，更严重的最坏情况干旱和更高的发生概率。这样的曲线也突出了树状水文学对概率干旱评估的价值。我们的结果表明，基于历史测量数据中最坏情况的当前水管理策略可能会低估自然干旱的潜在强度。如果气候变化下的低流量幅度与自然流量最低同时发生，那么不列颠哥伦比亚省南部沿海小流域的河流径流干旱严重程度可能会超过过去350年来的最高水平。官方版权（C）2016，由Elsevier B.V.保留所有权利。

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