1961—2014年鄱阳湖流域降雨侵蚀力时空变化特征

Spatial-Temporal Variation of Distribution of Rainfall Erosivity in the Poyang Lake Basin During 1961-2014

基于1961—2014年逐日降雨数据,引用集中度与集中期概念,借助数理统计及空间插值技术,分析鄱阳湖流域降雨侵蚀力分配特征。结果表明,鄱阳湖流域多年平均降雨侵蚀力为9 537. 9 MJ·mm·hm-2·h-1,年际变化呈上升趋势,但趋势不显著(P>0. 05)。空间上,降雨侵蚀力自西南向东北逐渐增加,倾向率的空间格局与降雨侵蚀力一致,但大多数站点趋势不显著(P> 0. 05)。降雨侵蚀力多年平均集中度为0. 49,多年平均集中期为152. 4°(对应6月),且集中度降低,集中期推迟,但两者变化均不显著(P>0. 05)。空间上,集中度自西南向东北方向逐渐增加,但集中期空间格局分散,无明显规律。1961—2014年降雨侵蚀力整体分布格局尚未改变,但高、低值区中心处于不断变化中;集中度各年代空间分布多为西南低东北高,而集中期空间格局特征不明显。

Rainfall erosivity reflects the potential ability of soil erosion caused by rainfall,which is the core of soil erosive risk assessment.The spatial-variations of rainfall erosivity in the Poyang Lake Basin were investigated based on daily rainfall data during 1961-2014.Results show that average value of rainfall erosivity was 9 537.9 MJ·mm·hm^-2·h^-1,and had an insignificant upward trend.Rainfall erosivity and its tendency rate increased from southwest to northeast of Poyang Lake Basin,but the trend for most of the stations was insignificant.The annual average value of concentration degree of the rainfall erosivity was 0.49 with an insignificant decreasing trend,while annual average concentration period was 152.4°(corresponding to June)with an insignificant increasing trend.Spatial distribution of concentration degree was similar to rainfall erosivity,while concentration period had no obvious distribution pattern in the Poyang Lake Basin.Spatial pattern of rainfall erosivity did not change in the recent six decade while the centre of the high(low)value area changed in different decades.Dynamic of concentration degree for the last six decade was in accord with rainfall erosivity,while concentration period had no evident distribution pattern.