湄公河流域降水量时空分布特征分析
Analysis of Spatiotemporal Distribution Characteristics of Precipitation in the Mekong River Basin

利用2019~2023年老挝南欧江流域50个站的降水观测资料，分析了流域降水量的时空变化特征。结果表明：(1) 南欧江流域年平均降水量为1252.7 mm，呈现北多南少分布，年降水量主要集中在夏季；一级至七级流域年平均降水量为双峰型，三级流域和七级流域为两个波峰，其中七级流域降水量较其余流域大。(2) 雨季年平均暴雨日数东部流域多，西部流域少，二级流域河谷地区是暴雨日数最多的地区。(3) 流域出现暴雨时伴有短时强降水出现的站次占暴雨总站次的57.1%。流域8月伴有短时强降水的暴雨站次最多，10月最少。(4) 一级流域北部，二级、三级、四级流域南部，五级、七级流域东部雨季各站暴雨日中出现短时强降水的占比均在80%以上。(5) 海拔500 < H ≤ 1000 m区间流域累计暴雨站次最多，500 < H ≤ 1000 m海拔区域内的累计暴雨站次最少，但伴有短时强降水的暴雨站次占总暴雨站次的比例最大。
Using the precipitation observation data from 50 stations in the Nam Ou River basin in Laos from 2019 to 2023, the spatial and temporal variation characteristics of precipitation in the basin were analyzed. The results showed that: (1) The annual average precipitation in the Nam Ou River basin is 1252.7 mm, with a distribution of more precipitation in the north and less in the south, and the annual precipitation is mainly concentrated in summer; The annual average precipitation of the first to seventh-level basins is bimodal, with two peaks for the third-level and seventh-level basins, with the seventh-level basin having a higher precipitation than the other basins. (2) In the rainy season, the average number of rainstorm days is higher in the eastern basin and lower in the western basin. The valley area of the secondary basin has the highest number of rainstorm days. (3) The number of stations with short-term heavy precipitation during rainstorms in the basin accounted for 57.1% of the total number of rainstorms. The number of rainstorm stations with short-term heavy rainfall in the basin is the highest in August and the lowest in October. (4) In the northern part of the first-level basin, the southern part of the second-, third-, and fourth-level basins, and the eastern part of the fifth- and seventh-level basins, the proportion of short-term heavy precipitation in rainstorm days at each station during the rainy season is over 80%. (5) The number of accumulated rainstorm stations in the basin with an altitude of 500 < H ≤ 1000 m is the largest, while the number of accumulated rainstorm stations in the area with an altitude of 500 < H ≤ 1000 m is the smallest, but the proportion of rainstorm stations with short-term heavy precipitation to the total number of rainstorm stations is the largest.