基于流域储水量精细化模拟的干旱指数构建及应用

Construction of drought index based on high-resolution simulation of watershed water storage and its application/

为构建一种客观反映河道槽蓄量、水库蓄水量和土壤含水量联合亏缺的干旱指数,以秦淮河流域为研究区,基于500 m×500 m分辨率的VIC-FLASH模型,通过精细化模拟流域河道、水库和土壤中存储水量的变化过程,构建了标准化流域储水指数(SWSI),并应用SWSI对1980—2019年秦淮河流域历史干旱事件和干旱特征进行分析,验证了其可靠性和应用优势。结果表明:高分辨率VIC-FLASH模型可以较好地模拟流域储水量时空分布,流量过程模拟结果平均相对误差为10.6%,流域内6座水库实测与模拟蓄水量相关系数为0.53~0.86;SWSI可以准确识别干旱事件和反映区域干旱严重程度,干旱烈度与实际受旱面积的相关系数为0.88;1980—2019年逐日SWSI与标准化径流指数和土壤含水量距平指数的相关系数分别为0.89和0.98;SWSI不仅可以定量反映流域储水量的亏缺状态,而且可以更加客观地反映旱情时空演变过程。

In order to construct a drought index that can reflects the combined water deficit of river channel water storage,reservoir water storage,and soil moisture content,a standardized watershed water storage index(SWSI)was constructed based on VIC-FLASH(variable infiltration capacity-flexible large scale hydrological routing)model with a resolution of 500 m×500 m.The reliability and advantages of SWSI were verified through its application in the Qinhuai River Basin to identify historical drought events and analyze drought characteristics from 1980 to 2019.The results showed that the high-resolution VIC-FLASH can well simulate the spatiotemporal distribution of water storage in the basin,with the average relative error of the flow process simulation being 10.6%,and the correlation coefficients between the measured and simulated water storage of six reservoirs in the basin were 0.53 to 0.86.SWSI can accurately identify drought events and reflect the severity of regional drought,with the obtained correlation coefficent between the drought severity and the actual area affected by drought reaching 0.88,and the correlation coefficients of daily SWSI with standardized runoff index and soil moisture anomaly percentage index from 1980 to 2019 were 0.89 and 0.98,respectively.SWSI can not only quantitatively and objectively reflect the deficit state of water storage in the basin,but also describe the spatiotemporal evolution process of drought more objectively.