Variation Characteristics and Design Condition of the Yellow River Water and Sediment

Based on the actual measured water and sediment data of main hydrologic stations located on the tributaries and the Yellow River,the basic characteristics and the main variation of the Yellow River water and sediment were analyzed.Considering of present planning research,the Yellow River water and sediment in different level years were forecasted.The design condition and representative series of water and sediment applying to a comprehensive plan for river basin and special research were proposed.The results show that insufficient water,excessive sediment and imbalance of the two are the basic characteristics of the Yellow River.Since 1986,the water and sediment of the upper and middle reaches have been greatly reduced.The natural runoff proportion of flood season declines and the runoff condition which is beneficial to sediment transport reduces significantly.It is estimated that the Yellow River's mean annual natural runoff will be 51.98 billion and 51.48 billion m3 respectively,the mean annual natural sediment are 1.05 billion ~ 1.10 billion and 0.95 billion ~ 1.0 billion tons in 2020 and 2030 respectively.According to 1956-2000 water and sediment series of 2020 level year,the 1968-1979 combined with 1987-1996 are chose as representative series of water and sediment.In the series,the mean annual water and sediment of Longmen,Huaxian,Hejin and Zhuangtou are 27.803 billion m3 and 1.077 billion tons,of which,in the first 12 years,the mean annual water and sediment are 29.017 billion m3 and 1.148 billion tons and in the last 10 years,the mean annual water and sediment are 26.347 billion m3 and 0.993 billion tons.