1951-2018年韶关不同量级降雨侵蚀力变化

降雨是引起土壤水蚀的主要动力因子之一,为探讨韶关市不同量级降雨对土壤水蚀特征造成的影响,选取1951—2018年韶关市逐日降雨量数据,采用日降雨侵蚀力模型计算降雨侵蚀力,利用变异系数、趋势系数分析不同时间尺度各量级降雨侵蚀力的变化。结果表明:(1)68年来韶关市年均降雨侵蚀力为9 314(MJ·mm)/(hm~2·h·a),变异系数为0.29,属于中等变异;(2)年降雨量、降雨日数、侵蚀性降雨量和降雨日数均呈上升趋势,而非侵蚀性降雨量和降雨日数则呈下降趋势,且暴雨量和暴雨侵蚀力呈较明显上升趋势,说明韶关市降雨更为集中,降雨侵蚀力增加;(3)大雨以上量级的降雨日数和降雨量占总降雨日数和总降雨量的比例分别为43.91%,51.15%,而其引起的降雨侵蚀力占总降雨侵蚀力比例却高达77.05%。研究结果为韶关市的土壤侵蚀的监测和水土保持工作提供参考。

Variations of Rainfall Erosivity of Different Magnitudes in Shaoguan from 1951 to 2018

Rainfall is one of the main dynamic factors that cause soil water erosion. In order to explore the effects of different levels of rainfall on the characteristics of soil water erosion in Shaoguan City, the daily rainfall data of Shaoguan City from 1951 to 2018 were selected, the daily rainfall erosivity model was used to calculate the rainfall erosivity, and the variation coefficient and trend coefficient were used to analyze the changes of rainfall erosivity indifferent time scales. The results indicated that: (1) The average annual rainfall erosivity of Shaoguan City in 68 years was 9 314 (MJ·mm)/(hm²·h·a), and the variation coefficient was 0.29, which was a medium variation. (2) The annual rainfall, rainfall days, erosive rainfall and rainfall days showed an upward trend, while the non-erosive rainfall and rainfall days showed a downward trend, and heavy rainfall volume and rainstorm erosivity showed an obvious upward trend, indicating that rainfall was more concentrated and rainfall erosivity increased in Shaoguan City. (3) The proportion of rainfall days and rainfall over heavy rain to total rainfall days and total rainfall was 43.91% and 51.15%, respectively, while the proportion of rainfall erosivity caused by heavy rain to total rainfall erosivity was 77.05%. The results could provide reference for soil erosion monitoring and soil and water conservation in Shaoguan City.