【摘要】 "水文法"是目前分析黄河水沙变化原因的常用方法,而黄河泥沙多产生于黄土高原的暴雨洪水期,雨量集中、历时短、强度大,以往建立的降雨输沙模型中采用的降雨因子多基于日尺度降雨数据计算,不足以反映短历时的暴雨集中程度。基于无定河降雨摘录资料,以5 min为统计时段,采用动态泰森多边形法计算了短历时降雨特征指标,并通过MK法分析了降雨指标的变化趋势。采用双累积曲线法及MWP法等识别了无定河流域天然下垫面代表时期,构建了无定河流域天然时期降雨输沙经验模型,并与基于日降雨数据的天然输沙量计算结果进行对比。结果表明:①无定河流域0.1、0.4、0.5 mm/5 min等3种雨强以上降雨总量的变化趋势不显著;②1970年以前可作为无定河流域天然下垫面代表时期;③基于降雨摘录数据的降雨输沙模型更能体现黄土高原暴雨洪水的产沙特性。更多还原

【Abstract】 "Hydrological method"is a common method to analyze the cause of water and sediment variation of the Yellow River, while the sediment mainly comes from the loess plateau during storm flood period, with concentrated rainfall and great intensity in short duration. Most of rainfall factors used in previous models of precipitation-sediment are calculated with daily time scale rainfall data, which is not enough to reflect concentrative degree of rainstorm with short duration. This paper calculated rainfall index with dynamic thiessen polygon method based on short duration rainfall data of Wuding River, of which statistical time range is five minutes and it analyzed the trend of the rainfall index by MK method. It identified representative period of natural state by curve of double cumulate method and MWP method and it constructed empirical model of precipitation-sediment under natural state. Through comparing the natural sediment amount with that calculated by the model based on daily rainfall data, the results showthat a)the variation trend of rainfall capacity more than 0.1 mm, 0.4 mm and 0.5 mm per 5 minutes is not significant in Wuding River basin; b)the period before 1970 can be adopted as representative period of natural underlay in Wuding River basin; c)that model of precipitation-sediment based on rainfall extract data can better reflect characteristics of sediment yielding in the loess plateau during storm flood.更多还原