抚河流域气象干旱向水文干旱传播的影响机制研究

Influencing mechanism of meteorological drought to hydrological drought propagation in the Fuhe River Basin

气象干旱是水文干旱发生的前兆,探究影响气象干旱向水文干旱传播的主要因素对建立有效的基于气象干旱的水文干旱监测预警具有重要意义。以抚河流域为例,采用标准化降水指数和标准化径流指数分别评估气象干旱和水文干旱,并构建基于流域分布式二元水循环模型的干旱传播评估方法,采用多因素综合影响贡献量分解法量化气候变化和人类活动对干旱传播变化的贡献。结果表明:建立的抚河流域分布式二元水循环模型模拟流域出口断面流量的纳什效率系数大于0.85,相对误差在5%之内;气象干旱向水文干旱传播关系变化的时间是1980s—1990s。相对于1956—1990年,1991—2019年气象干旱向水文干旱的传播率降低了8.3%;在气象干旱向水文干旱传播的影响中,气候变化的减缓作用占主导地位,贡献量为-9.9%;其次是人类活动的加剧作用,贡献量为1.6%;降水作为干旱的主要致灾因子,变化期增加了144.3 mm,这对于减弱气象干旱向水文干旱传播的敏感性起到主要作用。

Meteorological drought serves as a precursor to the occurrence of hydrological drought,so exploring the main factors influencing the propagation of meteorological drought to hydrological drought is of vital significance to the establishment of an effective monitoring and early warning system for hydrological drought based on meteorological drought.In the case of the Fuhe River Basin(hereinafter referred to as FRB),the evaluation of meteorological drought and hydrological drought was conducted respectively using the standardized precipitation index and the standardized runoff index.To quantify the impact of climate change and human activities on the propagation of drought,a drought propagation assessment method was developed.This method employed a distributed binary water cycle model,namely WEP-L model,and incorporated a multi-factor integrated impact contribution volume decomposition approach.Through this framework,the contributions of climate change and human activities to the changes in drought propagation could be accurately measured.The findings indicate that a distributed binary water cycle model was successfully constructed for the FRB.The Nash efficiency coefficients of the simulated flow at the basin outlet section were all above 0.85,and the relative errors were all within 5%.The analysis revealed a shift in the relationship between meteorological drought and hydrological drought propagation during the period from the 1980s to the 1990s.Comparing the period from 1991 to 2019 with the reference period of 1956 to 1990,the propagation rate decreased by 8.3%.The dominant factor mitigating the propagation of meteorological drought to hydrological drought was climate change,contributing-9.9%;whereas human activities had a exacerbating effect,contributing 1.6%.Notably,precipitation,as the primary driver of drought,increased by 144.3 mm during the study period,playing a significant role in reducing the sensitivity of meteorological drought to hydrological drought propagation.