赣江上游平江流域降雨侵蚀力的时空分布特征

目的]研究赣江上游平江流域降雨侵蚀力的时空变化规律,为流域治理措施的制定提供参考。方法]利用平江流域内10个雨量站点1989—2018年共30 a的日降雨量数据,采用降雨侵蚀力日降雨简易计算模型和Mann-Kendall趋势检验等方法,对平江流域降雨侵蚀力的时间分布规律进行研究;借助ArcGIS 10.1中的克里金插值法对平江流域的降雨侵蚀力进行空间分析。结果]平江流域降雨侵蚀力在1989—2018年间平均值为4 233 MJ·mm/(hm~2·h·a),最大值为6 766.5 MJ·mm/(hm~2·h)(2015年),最小值为2 191 MJ·mm/(hm~2·h)(2003年);流域内30 a降雨侵蚀力变化较为平稳,年际间呈现出不显著的增加趋势,年内分布同降水量一致,表现为双峰型,分别在6月和8月。降雨侵蚀力在空间上表现为由东北向中南方向递减,而后向西南方向递增,最大值出现在北部城冈站附近,最小值出现在中南部龙口站附近。结论]平江流域降雨侵蚀力的时空分布特征与流域内降水时空分布基本一致。对流域水土流失防治工作而言,春季应尤其注意降雨侵蚀力较大且出现上升趋势的流域北部地区,夏季和冬季应更加注意流域西南部。

Spatiotemporal Variation of Rainfall Erosivity at Pingjiang Basin in Upstream of Ganjiang River

Objective] This study assessed the temporal and spatial variation of rainfall erosivity at Pingjiang basin in the upstream of Ganjiang River to provide a basis for the formulation of watershed management measures in this area.Methods] Daily precipitation data from 1989 to 2018 from ten stations in the Pingjiang basin were used. Rainfall erosivity was calculated using a simple algorithm, and temporal variation in rainfall erosivity was analyzed using the Mann-Kendall method and climate tendency rate. The spatial variation of rainfall erosivity was analyzed via the Kriging interpolation method using ArcGIS 10.1.Results] Annual rainfall erosivity from 1989 to 2018 at Pingjiang basin was 4 233 MJ·mm/(hm²·h·a), while the maximum value6 766.5 MJ·mm/(hm²·h·a)] occurred in 2015 and the minimum value2 191 MJ·mm/(hm²·h·a)] occurred in 2003. Rainfall erosivity at Pingjiang basin from 1989 to 2018 was relatively stable, showing an insignificant increasing trend in interannual distribution over the study period. The annual distribution was consistent with precipitation levels, showing a bimodal pattern in June and August. The spatial variation of rainfall erosivity at the basin showed a decreasing trend from the northeast to the central south and an increasing trend to the southwest. The maximum value appeared near Chenggang station at the north of the basin, and the minimum value appears near Longkou station at the south central of the basin.Conclusion] The spatiotemporal variations of rainfall erosivity in the Pingjiang basin are largely consistent with precipitation levels. For the prevention and control of soil and water loss, attention should be focused on the northern part of the basin in spring, and the southwestern basin during summer and winter.