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首页> 外文期刊>Canadian Water Resources Journal >Modelling Future Streamflow Extremes ― Floods and Low Flows in Georgia Basin, British Columbia
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Modelling Future Streamflow Extremes ― Floods and Low Flows in Georgia Basin, British Columbia

机译：模拟未来的极端水流-不列颠哥伦比亚省乔治亚盆地的洪水和低流量

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摘要

The Georgia Basin is one of the most hydrologically complex areas of Canada. Variations in temperature, precipitation and elevation influence the amount and form of water that drives Streamflow in its rivers and streams. Climate change could have major regional effects on air temperature, precipitation, evapotranspiration, and ultimately runoff. In previous work, zones of homogenous hydrologic processes were delineated within the basin. Watersheds were separated into three types: rainfall―driven streams, snowmelt―driven streams, and hybrid (mixed rainfall― and snowmelt-driven) streams. Climate change was shown to have major regional effects on each type of watershed, affecting the amounts and patterns of runoff. In the current study we consider changes in extreme hydrologic events, floods and low flows, in these watersheds. Climate data downscaled from the Canadian Coupled General Circulation Model for future time periods are used as inputs to a hydrologic model optimized for mountain watersheds. The discrepancies between observed and modelled streamflows are examined. While the model reproduces central tendency measures well, there are significant biases in the ability of the models to reproduce extremes. Output from the hydrologic model is used to assess relative changes in the frequency, timing, and magnitude of floods and low flows between present and future (2020, 2050 and 2080) climate scenarios. The models suggest that frequency of floods will increase in all watersheds under the projected climate scenarios. In rainfall―driven streams, flood events increase in number, but not in magnitude. In hybrid streams, winter events occur more often while summer snowmelt flood events occur less often. In snowmelt-driven streams, the magnitude and duration of summer floods increase. Low flows in rainfall―driven streams maintain the same frequency and magnitude but occur over an extended period of time during summer. Hybrid streams show an increase in frequency, a decrease in magnitude, and a shift in time of occurrence of low flows to summer rather than winter. In snowmelt-driven streams, low flow events occur less often largely moderated by increased flow due to an overall increase in winter Streamflow in a warmer climate.
机译：乔治亚盆地是加拿大水文最为复杂的地区之一。温度，降水和海拔的变化影响驱动河流和溪流中水流的数量和形式。气候变化可能会对气温，降水，蒸散和最终径流产生重大的区域影响。在以前的工作中，在盆地内划出了均匀水文过程的区域。流域分为三种类型：降雨驱动流，融雪驱动流和混合（混合降雨和融雪驱动）流。事实证明，气候变化对每种流域都有重要的区域影响，影响径流量和模式。在当前的研究中，我们考虑了这些流域中极端水文事件，洪水和低流量的变化。从加拿大耦合总循环模型对未来时间段缩减的气候数据被用作针对山区流域优化的水文模型的输入。检查观察到的流量与建模流量之间的差异。虽然模型很好地再现了集中趋势测度，但是模型再现极端情况的能力存在重大偏差。水文模型的输出用于评估当前和未来（2020年，2050年和2080年）气候情景之间洪水和低流量的频率，时间和幅度的相对变化。这些模型表明，在预计的气候情景下，所有流域的洪灾频率将增加。在降雨驱动的河流中，洪水事件数量增加，但幅度没有增加。在混合流中，冬季事件发生的频率较高，而夏季融雪洪水事件的发生频率较低。在融雪驱动的河流中，夏季洪水的数量和持续时间增加。降雨驱动的河流流量低，保持相同的频率和大小，但夏季会持续较长时间。混合流显示出频率增加，幅度减小以及发生少量水流的时间转移到了夏季而不是冬季。在融雪驱动的溪流中，由于冬季气温升高，冬季溪流总体增加，因此流量增加引起的低流量事件较少发生。

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