基于Budyko假设的沂河流域径流变化归因识别

Attribution Identification of Runoff Change in Yihe River Basin Based on Budyko Hypothesis

气候变化和人类活动是导致径流变化的主要原因,因此计算气候变化和人类活动对沂河流域径流变化的贡献率可为缓解沂河流域水资源紧张提供一定的参考依据。以山东省沂河流域为研究对象,基于1960—2016年的气温、风速、降水和流量等水文气象数据,首先采用Mann-Kendall、有序聚类分析法和累积平距法分析降水量及径流量的变化趋势及突变点,最后采用Budyko水热耦合平衡方程,定量计算了气候变化和人类活动对径流变化的贡献率。结果表明:1960—2016年沂河流域年径流深呈现显著减小趋势,且在1975年和2003年发生突变,因此将径流序列分为1960—1975年(基准期),1976—2003年(变化期Ⅰ)和2004—2016年(变化期Ⅱ)3个阶段。基于Budyko水热耦合平衡方程计算变化期Ⅰ和变化期Ⅱ中降水、潜在蒸散发和下垫面对径流变化的贡献率,发现导致沂河流域变化期Ⅰ径流减少的主要原因是下垫面条件和降水的改变,贡献率分别为51.42%,49.43%,潜在蒸散发的减少导致径流增加,贡献率为-0.85%;导致变化期Ⅱ径流减少的最主要原因是下垫面条件的改变,占73.11%,其次是降水,贡献率为42.53%,潜在蒸散发的减少导致径流量增加,占比为-15.64%。综上,沂河流域径流变化是人类活动和气候变化共同作用的结果,随着经济社会发展,下垫面条件改变对径流变化的影响越来越大。

Climate change and human activities are the main causes of runoff change. Therefore, calculating the contribution rate of climate change and human activities to runoff change in the Yi River basin can provide a certain reference for alleviating the water resources stress in the Yihe River basin. Based on the hydrometeorological data of temperature, wind speed and precipitation from 1960 to 2016, Mann-Kendall, ordered cluster analysis method and cumulative horizontal distance method were applied to analyze the variation trend and change point of precipitation and runoff in the Yihe Rver basin. Effects of climate change and human activities on runoff change were quantified by Budyko hydrothermal coupled equilibrium equation. The results showed that: the annual runoff depth of the basin decreased significantly from 1960 to 2016, and change points were in 1975 and 2003, respectively;Therefore, the runoff sequence of Yihe River was divided into three stages: 1960—1975(base period), 1976—2003(change period Ⅰ) and 2004—2016(change period Ⅱ);based on Budyko hydrothermal coupled equilibrium equation, the contributions of precipitation, potential evapotranspiration and underlying surface to runoff change in change period Ⅰ and Ⅱ were calculated, respectively;the results indicated that decreasing runoff in change period Ⅰ resulted from underlying surface and precipitation change, with contribution rates of 51.42% and 49.43%, respectively;the decreasing of potential evapotranspiration led to increasing runoff, with contribution rate of-0.85%;the main reason for decreasing runoff in the change period Ⅱ was the change of underlying surface conditions, accounting for 73.11%, followed by precipitation, accounting for 42.53%;the decrease of potential evapotranspiration led to the increase of runoff, and the contribution rate was-15.64%. The change of runoff in Yihe River Basin was impacted jointly by human activities and climate change. With the development of economy and society, the influence of underlying surface change of runoff was increasing.