Abstract:
Background The annual sediment transport in the Yellow River is the expression carrier for soil erosion on the Loess Plateau of the middle reaches of the Yellow River, with an average of 1.6×109 t/year in weak soil erosion control. As of 2015, the comprehensive management measures of soil and water conservation in the Loess Plateau of the middle reaches of the Yellow River reached 260 000 km2, and the degree of governance exceeded 62%. The annual sediment transport volume of the Yellow River has not exceeded 5×108 t/year in more than 10 years, and the minimum volume of the annual sediment transport is < 108 t/year. At present, China takes the protection and management of the Loess Plateau area in the Yellow River basin as an important strategic measure, therefore, it is of great practical significance to study the response characteristics and degree of annual sediment transport in the Yellow River to soil and water conservation.
Methods 22 rainfall factors and soil erosion control factors were selected, and regression analysis was used and the statistical analysis of the annual sediment transport of the Yellow River in 1954 to 2015 was conducted in three periods.
Results 1) From 1954-1966, only a factor of "July to August rainfall in Hekouzhen-Wubao section" "interpreted" the change of the annual sediment transport of the Yellow River by 78%. 2) During the period from 1967 to 1987, a nonlinear regression model composed of soil erosion control degree and three rainfall factors were selected by stepwise regression. 3) From 1988 to 2015, a factor of "controlled percentage of soil erosion" solely "interpreted" the change of the annual sediment transport of the Yellow River by nearly 80%. The changes of the calculated results in the three periods indicated that the response of annual sediment transport amount to soil and water conservation in the four stations of the Yellow River was from not obvious to significant with the increase of soil erosion control degree. Among them, before 1960s, the annual sediment transport of the Yellow River was insensitive to soil and water conservation. 1960s to 1980s, the effect of soil and water conservation on reducing the annual sediment transport of the Yellow River appeared, the annual sediment transport of the Yellow River responded to the degree of soil erosion control, the degree of soil erosion control was the main factor that causes the fluctuation and decrease of annual sediment transport in the Yellow River.
Conclusions Since the mid-1980s, soil and water conservation plays a significant role in reducing the annual sediment transport of the Yellow River, The annual sediment transport of the Yellow River has a strong response to the degree of soil erosion control; when the controlled percentage of soil erosion is more than 60%, with a confidence of 95%, the annual sediment transport of the Yellow River is less than 600 million t/year; In recent years, the amount of annual sediment transport reduction by the soil and water conservation has exceeded 109 t/year.