Increasing trends in rainfall erosivity in the Yellow River basin from 1971 to 2020

Hourly precipitation data from 1971 to 2020, collected from 98 stations distributed across the Yellow River basin, were analyzed to detect changes in characteristics on rainfall and rainfall erosivity for all storms and storms with extreme erosivity (greater than 90th percentile). Results showed that over the past 50 years, rainfall erosivity at both event and seasonal scales over the whole basin increased significantly (p < 0.05) with rates of 5.46% and 6.86% decade-1, respectively, compared to the 1981-2010 average values. Approximate 80% of 98 stations showed increasing trends and 20% of stations had statistically significant trends (p < 0.1). The increase of rainfall erosivity resulted from the significant increasing trends of average storm precipitation (p < 0.1), duration (p < 0.1), rainfall energy (p < 0.05) and maximum 1-h intensity (p < 0.05). In addition, the total extreme erosivity showed significant upward trends at a relative rate of 6.05% decade(-1) (p < 0.05). Extreme erosivity storms occurred more frequently and with higher rainfall energy during the study period (p < 0.05). Trends for seasonal total and extreme erosivity were also estimated based on daily rainfall data, and the changing magnitudes were similar to those based on hourly rainfall data, which suggested daily rainfall can be applied to detect interannual and long-term variations of rainfall erosivity in the absence of rainfall data with higher resolution. It was suggested that soil and water conservation strategies and vegetation projects conducted within the Yellow River basin should be continued and enhanced in the future.