In order to explore the effects of land-use and climate change on the runoff and sediment of the area in Loess Plateau

the Lanhe River basin in the upper reaches of Fenhe River was selected as the study area

where the ecological restoration effect was very significant. Based on the annual precipitation data

the annual runoff data and the annual sediment data of the Lanhe River from 1955 to 2018

the hydrological trend and the abrupt change were studied by Mann-Kendall test

Sliding t-test

and YAMAMOTO Index method. The law of the runoff and sediment change was analyzed by flow and sediment duration curve method

and the contribution of land-use and climate change to the runoff and sediment variation was quantitatively researched by double accumulation curve method. The results indicated that:From 1955 to 2018

precipitation had insignificant increasing trend

while both runoff and sediment load had significant reduction trends

with average annual change rates of —0.65 mm and —38.95 t/km2

respectively. Both of the runoff and sediment changed abruptly in 1983 and 1999 synchronously. Compared to the period 1 of base (1955-1982)

the average annual runoff and sediment load in the period 2 of soil and water conservation (1983-1998) decreased by 29.07 mm and 5 917.88 t/km2 respectively

and in the period 3 of Grain for Green project (1999-2018)

the amount of runoff and sediment load decreased by 33.18 mm and 6 967.34 t/km2 respectively. The runoff and sediment load were analyzed by the duration curves

it was found that both of the runoff and sediment load showed a decreasing trend no matter in flood period

mean-flow period or in drought period

and the decreasing degree of sediment load was much greater than the changing degree of runoff. The contribution rates of land-use change to runoff and sediment reduction in the period 2 of soil and water conservation were 83.21% and 83.52% respectively in the basin

and they were 117.88% and 103.48% respectively in the period 3 of Grain for Green project. It can be seen that the change of land-use was the dominant factor of the variation of runoff and sediment in different periods

while climate change had little effect in the basin. Under the background of global climate change

soil and water conservation measures based on vegetation restoration should be carried out by adjusting the land-use structure and optimizing the land use mode in the basin

which is the fundamental approach to soil erosion control and ecological protection on the Loess Plateau.