基于Budyko假设的渭河径流变化归因识别

定量评价河川径流量变化特征,开展其归因识别研究是制定气候变化应对策略与合理利用水资源的基础。以渭河流域为研究区,采用Mann-Kendall趋势检验法、双累积曲线等方法分析渭河流域1958—2015年的气候、水文要素变化特征,采用基于Budyko水热耦合平衡理论的水量平衡法估算径流变化对各驱动因素的弹性系数,定量评价气候变化和人类活动对径流变化的贡献率。结果表明:渭河流域咸阳、张家山、状头站的年径流量呈显著减少趋势,径流深减少速率分别为:-1.520、-0.501、-0.322 mm/a。3个站控制流域面平均降雨量呈非显著性减少趋势,年潜在蒸散发呈非显著增加趋势。剧烈的人类活动如工农业用水、大规模水土保持措施的实施及退耕还林草等引起的下垫面变化是径流量减少的主要因素,渭河干流和泾河流域下垫面变化对径流减少的贡献率均超过了60%,降雨变化贡献次之,潜在蒸散发的影响最小。

Attribution of runoff variation in the Wei River basin based on the Budyko hypothesis

In recent years, numerous rivers around the world have shown significant changes in runoff due to climate change and human activities. Investigating the causes of changes in runoff is greatly helpful in adapting to climate change and intensive human activities. The present study applied the Mann-Kendall test and the double mass curve method to assess the temporal trends of hydro-climatic variables in the Wei River basin during 1958-2015. The results showed that annual runoff at all three hydrological stations (Xianyang, Zhangjiashan, and Zhuangtou) exhibited a significant decreasing trend (P < 0.05). Annual rainfall and potential evapotranspiration showed decreasing and increasing trends, respectively, but neither were significant. Double mass curve analysis between annual runoff and precipitation showed abrupt changes in annual runoff in the Wei River basin. The periods before abrupt-change points, when runoff retained relatively pristine status and was affected by limited human activities, were regarded as baseline periods. Using the abrupt-change points, we obtained baseline periods of 1958-1970, 1958-1996, and 1958-1992 at Xianyang, Zhangjiashan, and Zhuangtou stations, respectively. The runoff elastic coefficients at each station were estimated using the Budyko hydrothermal equilibrium equation. The results showed that runoff depth was sensitive to the changes in land surface. Compared with runoff in the mainstream Wei River and the Jing River, runoff in the Beiluo River was less sensitive to climate changes. Land surface changes played a dominant role in runoff reduction, followed by precipitation and potential evapotranspiration. Particularly in the mainstream Wei River and Jing River, land surface changes resulting from various human activities contributed more than 60% of runoff reduction.