1960-2017年重庆市不同量级降雨侵蚀力R值的时空变化特征

Spatio-temporal Variations of Rainfall Erosivity R Values of Different Magnitudes in Chongqing from 1960 to 2017

降雨是引起土壤侵蚀的主要动力之一,探究不同量级降雨侵蚀力的时空变化特征,以期为重庆市水土流失防治提供参考。选取1960—2017年重庆市及周边42个站点24 h降雨数据,按雨量等级表将其划分为不同量级降雨,利用简易模型计算R值,应用气候倾向率、变异系数、普通Kriging插值分析重庆市各量级降雨侵蚀力的时空演变特征。结果表明:(1)研究期内重庆市年均R值为5 751.55(MJ·mm)/(hm^(2)·h·a),变异系数为0.19,属中等变异;(2)不同量级降雨侵蚀力对年均R值的贡献率为大雨(34.82%)>暴雨(30.53%)>中雨(23.93%)>大暴雨(10.53%),其中大暴雨侵蚀力的气候倾向率最大,对年降雨侵蚀力的上升贡献率最高;(3)降雨侵蚀力年内分配极度不均,54.19%集中分布在夏季,仅有0.91%分布在冬季;(4)年均降雨侵蚀力和各量级降雨侵蚀力空间分布呈东高西低的格局。通过对重庆市不同量级降雨侵蚀力的分析,明确了发生土壤侵蚀可能性较高的时期和地区,为因地制宜制定水土保持措施提供参考。

Rainfall is one of the main driving forces of soil erosion. In order to explore the spatial-temporal variations of rainfall erosivity with different magnitudes, the 24 h rainfall data of 42 meteorological stations in Chongqing and its surrounding stations from 1960 to 2017 were selected so as to calculate the R value by the daily rainfall erosivity model. And the spatial-temporal variation of different magnitudes rainfall erosivity in different time scales were analyzed by utilizing the climate tendency rate, variation coefficient and ordinary Kriging. The results showed that:(1) The average annual R value of Chongqing was 5 751.55(MJ·mm)/(hm^(2)·h·a) in 58 a, and the variation coefficient of the average annual R value was 0.19, which between 0.1 and 1, belonging to a medium variation.(2) The order of contribution rate of rainfall erosivity of different magnitudes to annual R value was heavy rain(34.82%)>rainstorm(30.53%)>moderate rain(23.93%)>downpour(10.53%), and the increasing trend of downpour erosivity was dominant in annual rainfall erosivity.(3) The distribution of annual R value was extremely uneven, with 54.19% concentrated in summer and only 0.91% in winter.(4) The annual and each magnitude rainfall erosivity showed a decreasing trend from east to west. This study clarifies the periods and areas with high possibility of soil erosion, protective measures are supposed to take to control soil erosion according to local conditions.