北京市近40年来降雨侵蚀力时空变异特征

Temporal and Spatial Variations of Rainfall Erosivity in Beijing in Recent 40 Years

[目的]降雨侵蚀力可以反映降雨对土壤侵蚀的潜在作用,是评价区域土壤侵蚀风险的重要指标。分析北京市1981—2020年降雨侵蚀力时空变异特征,对科学评估和防治区域水土流失风险具有重要意义。[方法]基于1981—2020年北京市及周边地区119个雨量站点逐日降水数据,采用Kriging插值、Mann-Kendall非参数检验、小波分析等方法对北京市年降雨侵蚀力和中雨(10~25 mm)、大雨(25~50 mm)、暴雨(≥50 mm)降雨侵蚀力的空间分布、趋势变化以及周期变化特征进行分析。[结果]北京市1991—2020年年降雨侵蚀力范围为1691.51~3914.89(MJ·mm)/(hm^(2)·h·a),年降雨侵蚀力与大雨和暴雨的降雨侵蚀力的空间分布特征相似,与中雨的降雨侵蚀力的空间分布特征有所差异。空间整体上表现为从东北向周围递减的趋势。近40年来,北京中雨侵蚀力呈显著增加趋势,年降雨侵蚀力、大雨、暴雨以及夏季7,8月的降雨侵蚀力变化趋势均不显著,且均没有发生显著的突变。局部区域如密云、平谷一带的年降雨侵蚀力下降趋势相对较大。年降雨侵蚀力以及中、大、暴雨的降雨侵蚀力变化的主周期约为25年,且存在2~3次“低-高”交替变化。[结论]研究结果可为北京开展水土保持工作、农业和生态保护等工作提供科学依据。

[Objective]Rainfall erosivity serves as an indicator to assess the potential impact of rainfall on soil erosion,playing a crucial role in evaluating regional soil erosion risk.Therefore,analyzing the temporal and spatial variations of rainfall erosivity in Beijing from 1981 to 2020 holds significant importance for scientifically assessing and preventing regional soil erosion risks.[Methods]This study employed Kriging interpolation,Mann-Kendall non-parametric test,and wavelet analysis based on daily precipitation data collected from 119 rainfall stations in Beijing and its surrounding areas between 1981 and 2020.These methods were utilized to analyze the spatial distribution,trend changes,and periodic fluctuations of annual rainfall erosivity as well as erosivity associated with moderate rain(10~25 mm),heavy rain(25~50 mm),and extreme rain(≥50 mm)in Beijing.[Results]The annual rainfall erosivity in Beijing ranged from 1691.51 to 3914.89(MJ·mm)/(hm^(2)·h·a)during the period from 1991 to 2020.The spatial distribution characteristics of annual rainfall erosivity exhibited similarities with heavy rain and rainstorm but differed from moderate rain patterns.Overall,there was a decreasing trend observed from northeast regions towards the surrounding areas.Over the past four decades,moderate rainfall erosivity demonstrated a significant increasing trend in Beijing;however,no significant mutations or trends were observed for annual rainfall erosivity,heavy rain events,rainstorms or July-August summer precipitation erosivity.Notably large decreasing trends were identified for annual rainfall erosivity within local areas such as Miyun and Pinggu districts.The main cycle for both annual rainfall erosivity and medium-to-heavy intensity precipitation lasted approximately twenty-five years with two to three alternating“low-high”changes.[Conclusion]The study can offer a scientific foundation for soil and water conservation,agricultural practices,and ecological preservation in Beijing.