Response of Runoff and Sediment Discharge to Precipitation Variation in the Kuye River Basin

The Kuye River basin is the first-order tributary of the middle Yellow River, water resources are important for the environment and development in this region. Since 1960s, runoff of the Kuye River basin has been dramatically decreased and the river basin has been facing serious water resources problems. In this study, we found that annual precipitation and different level precipitation had no significant change trend from 1966 to 2012, the runoff and sediment discharge had a significant decrease trend for the same period. There was an abrupt change for runoff in 1998 and for sediment discharge in 1999. The relationships between runoff, sediment discharge and precipitation had been changed obviously for the two periods, before and after the runoff transition point. For the later period, there was much less runoff or sediment discharge according to the observed data under the same precipitation, the runoff or sediment discharge was not sensitive to precipitation change. Precipitation is not the main cause of runoff and sediment discharge change, buthuman activities were responsible for runoff and sediment discharge decrease.