淮河流域近58年降水特征分析

为了更明确、具体地了解淮河流域降水的时空分布特征,基于1959～2016年淮河流域170个高密度站点逐日降水资料,采用Spearman秩次相关和对趋势分析较准确的成对斜率回归中值等统计方法,分析了流域不同级别降水的降水量、降水日数和降水强度等指标的时空分布特征。结果表明,淮河流域年降水南北差异较显著,由西北向东南递增,年降水量和降水日数最大的地区均位于流域最南部大别山地区,其值为最小值的2倍左右;平均日降水强度及年暴雨量和暴雨日数的分布相似,东部沿海地区和西南部山区为大值区,西北部海拔流域最高的地区为最小值分布区,在流域中部由西北向东南方向逐渐增多;平均暴雨强度的一个大值区位于流域中部偏西的河南驻马店地区,淮河流域极端强降水的发生地也集中在此地周围;流域整体年降水量有轻微下降趋势,降水日数明显减少(东北部地区尤其显著,干旱风险增加),导致平均日降水强度显著增加。这主要是由10mm以下的小雨尤其是0.1～1mm的微量降水的频数显著减少导致的,而50mm以上的暴雨各指标在流域整体上均无显著的变化趋势;流域春秋两季降水量呈减少趋势,夏冬两季降水量呈增加趋势,属于春秋变干、冬夏变湿的地区。

Analysis of Precipitation in Huaihe River Basin in Recent 58 Years

Based on the daily precipitation data at 170 high density stations in Huaihe River Basin, the Spearman rank correlation and the trend analysis methods were used to analyze the temporal and spatial characteristics of precipitation indicators in the basin. The results show that the annual precipitation in the Huaihe River Basin is significantly different spatially. The areas with the largest annual precipitation and precipitation days are in the southernmost part of the Dabie Mountains, with a value about twice of the minimum value. The average daily precipitation intensity and the distribution of annual rainfall/storm days are similar. The eastern coastal areas and the southwestern mountainous areas are with large value areas. The highest area in the northwest basins is the area with minimum value. The region with peak rainfall intensity is located in the west of the basin, which is the Zhumadian area, Henan Province, and the occurrence of extreme heavy rainfall is also concentrated around this area. The overall annual precipitation in the basin has a slight downward trend. The annual precipitation days decreased significantly, especially in the northeastern region, resulting in a significant increase in average daily precipitation intensity. This is mainly caused by the significant decrease in the frequency of the trace rainfall below 10 mm, especially from 0.1 mm to 1 mm. The indicators of the rainstorm above 50 mm have no significant trend overall. For the seasonal variations, the precipitation decreased in spring and autumn and increased in summer and winter during past several decades.