Analysis of precipitation characteristics on the loess plateau between 1965 and 2014, based on high-density gauge observations

The Loess Plateau is ecologically vulnerable and one of the most severely eroded areas in China. In this study, we used daily precipitation data from 170 meteorological stations for the period 1965 to 2014 to systematically analyze the spatiotemporal variability of annual precipitation on the plateau, and to determine the dominant factors influencing changes in annual precipitation. The average annual precipitation is between 400 mm and 600 mm in most regions of the plateau, and precipitation is concentrated in the summer months (June to August). The greatest precipitation is in the southeastern region, but the amount has declined over the past 50 years. Morever, there have been decreases in extreme precipitation events in the southeastern region, and only minor changes in the continuous drought. Erosive rainfall is closely related to the total annual precipitation across the Loess Plateau region, and has decreased along with the decreases in annual precipitation, especially in the southeastern region. Changes in erosive rainfall account for >80% of interannual precipitation variability over large areas of the Loess Plateau. The variability in annual precipitation on the plateau is mainly affected by changes in the intensity and frequency of precipitation; changes in the length of the rainy season have only a minimal effect. Precipitation frequency contributes about 30% to interannual precipitation variability across the region as a whole. However, the eastern region is predominantly affected by changes in precipitation intensity, which contributes about 70% of the variability. These results provide valuable information to determine the dominant factor(s) influencing annual precipitation on the Loess Plateau, and may also be useful in the prevention and control of drought and soil erosion on the plateau.