气候自然变异在气候变化对水资源影响评价中的贡献分析——Ⅰ.基准期的模型与方法

Evaluation on the influence of natural climate variability in assessing climate change impacts on water resources:Ⅰ. Model and methodology in baseline period

基于气候变化影响的水资源评价对水资源规划和管理具有重要意义,随着全球气候变化影响的加剧,这一研究显得越来越紧迫。在目前的气候变化研究中,很少考虑气候自然波动的影响(气候自然变异),常将所有的变化单独归因于气候变化的影响,这在气候变化的影响评价中可能导致错误的理解与判断。气候自然变异分析由于缺乏超长系列的数据资料而长期被人为避开。针对这一问题,本研究提出模型方法体系,通过历史基准期的长系列模拟来分析气候自然变异的影响。选取常用的1961～1990年水文系列作为基准期,提出一种基于拉丁超立方体抽样技术的季节分段抽样模拟方法,实现对气候自然变异的模拟。应用水文模型TOPMODEL对基准期的径流系列进行模拟,基于不确定性分析GLUE方法对基准期内水文模型参数不确定性进行分析,并探讨了气候自然变异的影响。研究结果表明,在气候变化影响评价中,气候自然变异的影响不可忽略,应在气候变化的影响中加以区分和界定。

Water resources assessment impacted by climate change is very important to water resources planning and management.This issue is becoming more urgent as evidences of intensifying climate change are growing.In the current research of climate change impact,climate natural fluctuation（variability） has seldom been studied separately.It keeps attributing all changes（runoff,e.g.） to climate change,which may lead to wrong understanding of climate change impact assessment.Since without long enough historical series,impacts of climate variability have been always avoided deliberately.Aiming at this issue,this study proposed a type of simulation methodology,which could analyze the effect of climate natural variability by means of reproducing long series based on the baseline period resampling.The wide used time horizon（1961-1990） was selected as baseline period.Based on Latin Hypercube Sampling（LHS） technique,a block sampling approach was proposed for climate variability simulation.TOPMODEL（TOPography based hydrological MODEL） as a hydrological model was employed,while GLUE（Generalized Likelihood Uncertainty Estimation） for hydrological model parameters calibration and uncertainty,and climate variability uncertainty was estimated.The results show that changes from climate variability has a comparable magnitude with that from climate change,which highlights the importance to separate impacts of climate variability from the total variation in assessing climate change,instead of attributing all changes to climate change solely.