广东北江流域降水集中度和集中期的时空变化特征

基于广东北江流域分布较均匀的18雨量站1965年-2009年日降水资料,统计出各站各年份降水集中度(PCD)和集中期(PCP)指标,然后基于该指标分析流域降水集中度和集中期多年均值、变化趋势、与年降水量相关性、丰水年枯水年合成分析的空间分布情况,以期研究流域降水年内非均匀分布的时空变化特征。结果表明:(1)降水集中度总体表现为从南向北递减;降水集中期主要表现为中北部的大部分区域较为提前,南部区域较为滞后。(2)大部分区域表现为年降水量随着降水集中度的下降而增加;南部区域年降水量随着降水集中期的滞后而减少,北部区域反之。(3)MK趋势检验表明,流域降水集中度、集中期均主要表现为上升,但不显著。(4)降水集中度空间分布上,丰水年与枯水年比较一致,但枯水年降水集中度更高;丰水年降水集中期差别较大,从流域平均来看,丰水年集中期较枯水年约滞后20天。

Spatio-temporal change characteristics of PCD and PCP in Guangdong Beijiang river basin

Based on the daily precipitation data between 1965 and 2009 from 18 rainfall stations in Guangdong Beijiang river basin and the definitions of Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP), this paper studied the intra-annual inhomogeneous distribution characteristics of the precipitation in the basin by analyzing the spatial distribution of the multi-year mean values, variation trend, correlation with annual precipitation, and wet-year and dry-year composite values of PCD and PCP. The results are as follows: 1) PCD generally decreased from south to north; PCP was earlier in most of the north-central basin, but relatively later in the southern basin. 2) Annual precipitation would increase as PCD decreased in most of the basin; as PCP delayed, annual precipitation in the southern basin would decrease but that in the northern basin would increase. 3) As the Mann-Kendall test showed, the PCD and PCP in the basin were mainly on the rise, but not in a significant manner. 4) The spatial distribution of PCD in wet years was similar to that in dry years, but the PCD of dry years was higher. The PCPs in wet years were much more varied than those in dry years. On average, the PCP in wet years lagged about 20 days behind that in dry years.