1961—2015年雅鲁藏布江流域降雨侵蚀力

降雨是土壤侵蚀的主要动力,也是风水蚀复合区沙漠化的主要驱动力。研究降雨侵蚀力时空变化对雅鲁藏布江流域土壤侵蚀的监测、评估、预报和治理具有重要意义。利用1961—2015年雅鲁藏布江流域8个气象站日降雨量气象资料,采用趋势系数、气候倾向率、MK检验等研究方法对雅鲁藏布江流域降雨侵蚀力时空变化进行分析。结果表明:雅鲁藏布江流域年降雨侵蚀力平均值为758.1 MJ·mm·hm^-2·h^-1,变差系数Cv值为0.29,趋势系数r值为0.3140。空间分布呈现由东向西逐渐递减的特点,东部可达2 000 MJ·mm·hm^-2·h^-1以上,最西部仅为200MJ·mm·hm^-2·h^-1。雅鲁藏布江流域年降雨侵蚀力总体呈波动上升趋势,其中嘉黎和波密站年降雨侵蚀力上升趋势明显,日喀则、泽当站年降雨侵蚀力呈下降趋势。通过MK检验及滑动T检验得知,流域内年降雨侵蚀力在1982年发生突变,年侵蚀性降雨突变不显著。雅鲁藏布江流域年降雨侵蚀力与侵蚀性降雨相关性显著。

Rainfall Erosivity in Yarlung Zangbo River Basin during 1961-2015

Rainfall is one of the main driving factors of soil erosion, and also one of the main driving forces of aeolian desertification in the wind-water compound erosion area. The study of temporal and spatial variation of rainfall erosivity is of great significance for monitoring,assessment, prediction and control of soil erosion in the Yarlung Zangbo River Basin. Based meteorological data of 8 weather stations from 1961-2015 in the Yarlung Zangbo River Basin, using the method of trend coefficient, climate tendency rate and Mann-Kendall test, the variations of the temporal and spatial in the Yarlung Zangbo River Basin were discussed.The results show that average annual rainfall erosion force was 758.1 MJ·mm·hm^-2·h^-1, with the coefficient of variation Cv of 0.29 and the coefficient of changed trend r of 0.3140.The rainfall erosivity decreases gradually from east to west in the Yarlung Zangbo River Basin. It can reach more than 2000 MJ·mm·hm^-2·h^-1 in the east, and only about 200 MJ·mm·hm^-2·h^-1 in the far west.The annual rainfall erosivity generally showed a fluctuating increase trend. Lhari and Bomi showed obviously increasing trend, while Shigatse and Zetang showed declining trend. Analysis using Mann-Kendall test method and sliding T test showed that the annual rainfall erosivity has abrupt change in 1982, but the erosive rainfall abrupt changewas not significant. The annual rainfall erosivity is significantly correlated with erosive rainfall, and also greatly affected by the distribution of erosive rainfall.