【摘要】 指定设计重现期或频率的水文设计值为随机变数 ,有一定的分布规律 ,表明它有相应的不确定性。文章采用统计试验法 ,分析计算了频率 P =0 .0 1%～ 2 0 %时水文设计值的统计参数 ,发现水文设计值不仅有随机的而且还有系统的偏差 ,系列愈短和偏态系数愈大时 ,其不确定性也呈愈大的趋势。为了减少不确定性 ,应尽可能延长系列 ,检查水文系列的代表性 ,对水文设计值在时空上作综合平衡分析 ,以期得到较为可靠的结果更多还原

【Abstract】 The hydrologic design values of specific design return period or frequency are random variables having certain distribution pattern,so there are some uncertainty in it. In this paper,the statistical testing technique is adopted,and the statitical parameters of the hydrologic design values are estimated for frequencies of P in 0.01%～20%.It is found that the hydrologic design values are not only of random bias,but also of systematic bias.Their uncertainty tends to increase as the series’ length is getting shorter and the skew coefficient larger.In order to decrease the uncertainty,the data series should be enlarged as possible,the representative of hydrologic series must be inspected,and comprehensive analysis of the hydrologic design values have to be carried out in time and space so that the more reliable results are expected.更多还原