Spatiotemporal Variation of Runoff and Its Influencing Factors in the Yellow River Basin, China

Runoff is an important component of water resources and also the basis for regional water resources development and utilization. In order to explore the new characteristics of the spatiotemporal variation of runoff in the whole Yellow River Basin, the spatiotemporal variation of runoff in the Yellow River Basin from 1982 to 2012 was studied based on the measured runoff data of 14 representative basins in the upper, middle, and lower reaches of the Yellow River Basin. The results showed that the runoff depth of the Yellow River Basin from 1982 to 2012 showed a decreasing trend, with a decrease rate of 0.3 mm/a. Among them, the discharge depth decreased significantly (p < 0.01) from 1982 to 1999, with a rate of 1.55 mm/a. Most of the area of the basin has a discharge depth of 0–10 mm, which is relatively dry. The area of higher runoff depth (40–100 mm) is decreasing and gradually concentrating in high-altitude steep-slope areas, while the area of lower runoff depth (0–10 mm) is increasing and spreading to low-altitude gentle-slope areas. After 1999, the discharge in the four sub-basins in the upper reaches decreased, and most of the sub-basins in the middle reaches also showed a decreasing trend, while the discharge in a few sub-basins, such as Qinhe River and Yiluo River, increased. The discharge depth of the sub-basins in the lower reaches increased, but the magnitude and rate of change of most of the sub-basins were consistent with the overall trend of the Yellow River Basin, which showed a decreasing trend.