珠江三角洲地区汛期降水时空演变特征

Spatiotemporal changes of precipitation characteristics in the Pearl River Delta region during flood season

科学认识降水时空演变特征对区域防洪减灾及水资源管理具有重要科学意义。利用珠江三角洲地区58个气象站点1961—2017年日降水资料,采用线性趋势、Mann-Kendall检验和空间地统计分析方法,探讨珠三角地区前、后汛期不同等级降水特征(降水量、降水日数及降水强度)时空演变规律。研究结果表明:(1)50多年来,珠三角地区前、后汛期降水量和降水强度均呈增加趋势,而降水日数则呈减少趋势;(2)除大暴雨外,前、后汛期各等级降水特征时间变化趋势相同,但存在明显的空间分布差异,珠江口附近、西南沿海及北部近山区是降水变化的敏感区;(3)前、后汛期降水事件均以小雨为主(占比>60%),而降水量主要来源于大雨事件(占比分别为28.7%和27.1%),但暴雨(5.6%和4.6%的降水日数贡献,25%和22.2%的降水量贡献)与大暴雨(1.3%和1.3%的降水日数贡献,12.6%和12.6%的降水量贡献)的相对贡献更为明显;(4)前、后汛期降水量的增加由大雨和暴雨降水量增加引起,降水日数减少是由于小雨降水日数减少,降水强度的增加来源于大暴雨以下等级降水强度增加。

The study of spatiotemporal changes of precipitation pattern is of great scientific significance for regional flood control and disaster reduction as well as water resource management.In this work,the daily precipitation data from 1961 to 2017 is collected from 58 meteorological stations in the Pearl River Delta region.Then the spatial-temporal changes of precipitation characteristics for different grades in early and latter rainy season are investigated by the linear trend,Mann-Kendall test and geospatial statistical methods.The results show that:(1)An upward trend is found both for the precipitation amount and precipitation intensity,while a downward trend is detected for the precipitation days,in early and latter rainy season;(2)All the precipitation grades,except for the heavy rainstorm,show the same tendency for the precipitation amount,precipitation days and precipitation intensity in early and latter rainy seasons,but show different spatial patterns,with the most sensitive for precipitation change located in the vicinity of the Pearl River Estuary,the southwest coastal region and the north near the mountainous area;(3)The precipitation events are dominated by light rain(more than 60%)in early and latter rainy season,while the precipitation amount is mainly contributed by heavy rain,accounting for 28.7%and 27.1%,respectively.However,the relative contributions of rainstorm and heavy rainstorm are more significant;(4)The increase of precipitation in early and latter rainy season is caused by the increase of heavy rain and rainstorm precipitation;the decrease of precipitation days is caused by the decrease of light rain precipitation days;and the increase of precipitation intensity is caused by the increase of precipitation intensity of grades below the level of heavy rainstorm.