Trends of precipitation intensity and frequency in hydrological regions of China from 1956 to 2005

• We examine the precipitation pattern in hydrological regions in China.
• Significantly increasing trend is found in precipitation intensity.
• Significantly decreasing trend is found in precipitation frequency.
• These trends vary in different hydrological regions and different seasons.

Daily precipitation data of 741 meteorological stations ranging from 1956 to 2005 were used to run a preliminary investigation of changes in temporal and spatial distribution of precipitation intensity and frequency in ten hydrological regions in China. Average annual and seasonal spatial values of indices of precipitation characteristics (i.e. precipitation amount, intensity and frequency) were obtained using a Kriging interpolation method. Temporal tendencies were calculated by Mann-Kendall's method. The trends of extreme rainfall events and precipitation-based droughts were also discussed in ten hydrological regions using the maximum daily precipitation and dry spell duration in a year. Results show that precipitation intensity has significant increasing trends while precipitation frequency has significant decreasing trends over China. Meanwhile precipitation has a major decline in autumn and a slight increase in winter. Both extreme rainfall events and precipitation-based droughts show a general increasing trend. The aggravated spatial and temporal unevenly distributed precipitation leads to more water shortage as well as floods in China.