长江上游水文干旱评估及其不确定性分析

Hydrological drought assessment and uncertainty analysis for the Upper Yangtze River

在基于频率计算的水文干旱评估中,往往由于资料长度较短或不连续等原因,致使水文变量的参数估计存在抽样引起的不确定性。以长江干流宜昌站1882—2009年的日径流数据为对象,采用正态分布拟合中长时间尺度下各时段累积径流量,并以多种正态性检验方法检验拟合效果,计算了不同时间尺度的径流干旱指数SDI,采用Monte-Carlo随机模拟验证了干旱指数计算的抽样不确定性,分析了长江上游干旱演变特征和不确定性对干旱评估的影响。结果表明,根据干旱指标评估干旱量级时,考虑不确定性的影响,可为更加准确有效的抗旱决策提供理论支撑,以期规避可能造成的减灾能力不足或抗旱资源浪费。

Sampling uncertainty of hydrological variables parameter commonly exists in frequency analysis-based hydrologica drought indices calculation due to the limited data length and discontinuousness. Based on the daily streamflow data of the Yichang Gauging Station from 1882 to 2009, the runoff drought index SDI of different time scales was calculated, and the sampling uncertainty of drought index calculation was verified by Monte-Carlo stochastic simulation, analyzing the influence of drought evolution characteristics and uncertainty on drought assessment in the upper reaches of Yangtze River. The results show that when evaluating drought magnitude according to drought index, considering the influence of uncertainty can pro- vide theoretical support for more accurate and effective on drought resistance decision, to avoid the possible lack capacity of disaster reduction or resources waste of drought-resistant.