黄河下游洪水调控指标研究

依据200余场次洪水观测资料,应用统计分析、实体模型试验和数学模型计算等方法,对洪水按漫滩程度、水流含沙量高低、流量过程线形态特征和洪峰与沙峰相位差进行了分类;分析了塑造主槽的洪水关键因子;研究了黄河下游洪水过程调控关键技术指标。研究表明,黄河下游河槽高效输沙和塑造主槽作用较大的平滩流量约为4000m3/s,流量为4000m3/s条件下的洪水输送的临界含沙量为50kg/m3;对于不漫滩洪水,首选方案应按当时主槽的平滩流量控制,且平滩流量下的洪水流量过程以接近矩形波过程较好,峰前水量占洪水总水量的25%以上,洪水历时不小于7d;对于漫滩洪水,应控制洪峰流量大于平滩流量的1.5倍且大于洪水平均流量的1.2倍,同时应尽量控制洪水涨水期水量与洪水总水量之比不小于0.5,并保持洪峰与沙峰同步运行,洪水历时不小于7d;洪水调控分组含沙量大小主要取决于悬沙及床沙的级配;洪水来沙系数的调控指标视洪水类型而异,不漫滩洪水为0.012kg·s/m6,漫滩洪水为0.015kg·s/m6,同时还应控制分组泥沙的来沙系数。

Study on Regulation Indexes of Flood in the Lower Reaches of Yellow River

According to the grade of floodplain, the flow sediment concentration, the features of discharge process line, and the difference between flood peak and sediment peak, the flood is classified based on the data of more than 200 floods using statistical methods. The simulation experiments and mathematical models, and the key factors related with main channels formed by flood are discussed, and the key regulation indexes of flood in the lower reaches of Yellow River are studied. Results show that the flat beach discharge, which has an important effect on transport sediment and on the formation of main channels, is about 4 000 m3/s, the critical amount of transport sandiness is 50 kg/m3; the non floodplain flood or common floodplain flood should be controlled according to the flat floodplain discharge of the main channel first, and the flood discharge process would be better to take a form close to rectangular wave, and the water quantity before flood peak would be better to take a value greater than 25 % of the total water quantity, and the flood time would be better to last more than 7 d; the floodplain flood peak discharge should be controlled to be bigger than 1.5 times of flat floodplain flood peak discharge and bigger than 1.2 times of average flood discharge, and at the same time, the ratio between water quantity in swelling period and total flood should be more than 0.5, and the flood peak should be kept in step with the sandiness peak, and the flood time would be better to last more than 7 d; the content of sediment in different regulation floods is determined by the ratio of suspended sand and bed sand; the regulation indexes of flood incoming sediments should be changed according to the flood type, non floodplain flood sediment coefficient is 0.012 kg.s/m6, the common floodplain flood sediment coefficient is 0.015 kg.s/m6, and the incoming sediments of grouping sandiness should be controlled, too.