Variation of sediment flux to the sea in various grain-size fractions in relation with the delta accretion of the Huanghe River in China

On the basis of the data from the period 1955~1990,a study has been made of the temporal variation of sediment flux into the sea of the Huanghe River in vario us grain-size fractions in relation with the delta accretion.The results show that the sediment fluxes in all the four grain-size fractions tend to decrease.The significance of decrease of the sediment flux in the four fractions decreases with the grain-size, i.e,the decreasing trend of fine sediment flux is clearer than that of coarse sediment.Since the 1970s,area of soil and water conservation measures in the Huanghe River drainage basin has increased,drawn water from the river by man has also increased,and annual precipitation has decreased.All these result in a decrease in the sediment flux into the sea of the Huanghe River in various grain-size fractions.After the measures were taken of soil and water conservation,the decrease of the sediment flux into the sea in fine grain-size fractions was more than that in coarse fractions.