Analysis on Characteristics and Reasons of Sediment Discharge Variation of the Yellow River in Last 50 Years

It collects the data of sediment discharge and runoff depth of key hydrometric stations of the Yellow River and its main tributaries in the last 50 years and studies the normal variation of absolute value of sediment discharge and relative runoff depth by using mathematical statistics.The outcomes show that the variation trends of absolute value of sediment discharge and relative runoff depth of all stations of the main river reduces or basically keeps the same except Tangnaihe Station on the upper reaches which the trend of sediment discharge increases comparing with the runoff depth.This is mainly caused by the debris-retaining reservoirs and soil and water conservation measures.The variations of absolute value of sediment discharge and relative runoff depth of each tributary are also mainly reduced or kept the same.While the sediment discharge of main tributaries situated in sediment contributing area of the middle river has no obvious changes comparing with the runoff depth under the conditions of runoff depth reduction.