This study presents an analysis of long-term rainfall variability and trends in the summer monsoon region of Southeast Asia, encompassing Lao People’s Democratic Republic (Lao PDR), Thailand, Vietnam, Cambodia, and Myanmar, as well as their respective river basins. Utilizing Climate Hazards Group InfraRed Precipitation with Station Data (CHIRPS) having a spatial resolution of 5 km spanning from 1981 to 2021, rainfall variability and trends were examined. Data preprocessing and geospatial analysis were conducted using R-Studio and ArcGIS software. The Mann–Kendall (MK) test and Sen’s slope estimator were employed for annual and seasonal rainfall trend analysis. Myanmar exhibited the highest average annual rainfall of 2137 mm during the study period, while Thailand had the lowest (1641 mm). Over the past four decades, the Peninsula Malaysian Basin experienced the highest average annual rainfall (2691 mm), whereas the Chao Praya Basin recorded the lowest (1311 mm). Increasing trends in rainfall were observed across all five countries and nine major river basins. Vietnam displayed the highest annual rainfall trend of 5.63 mm/year, while Lao PDR exhibited the lowest trend (3.16 mm/year). Among the river basins, the Chao Phraya Basin demonstrated the maximum annual rainfall trend (11.21 mm/year), while the Peninsula Malaysia Basin had the minimum trend (1.21 mm/year). These findings could significantly contribute to climate change monitoring in the region and can aid policymakers in sectors such as agriculture, urban planning, and disaster management.

中文翻译：

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东南亚夏季风区长期降雨变化及气候风险管理趋势

本研究分析了东南亚夏季季风地区的长期降雨量变化和趋势，包括老挝人民民主共和国（老挝）、泰国、越南、柬埔寨和缅甸及其各自的流域。利用 1981 年至 2021 年空间分辨率为 5 公里的气候灾害组红外降水站数据 (CHIRPS)，检查了降雨量的变化和趋势。使用R-Studio和ArcGIS软件进行数据预处理和地理空间分析。采用Mann-Kendall (MK) 检验和Sen 斜率估计器进行年度和季节性降雨趋势分析。研究期间，缅甸的年平均降雨量最高，为2137毫米，而泰国的年平均降雨量最低（1641毫米）。过去四十年，马来西亚半岛盆地的年平均降雨量最高（2691毫米），而湄南河盆地的年平均降雨量最低（1311毫米）。所有五个国家和九个主要河流流域的降雨量均呈增加趋势。越南的年降雨量趋势最高，为 5.63 毫米/年，而老挝人民民主共和国的年降雨量趋势最低（3.16 毫米/年）。各流域中，湄南河流域的年降雨量趋势最大（11.21 毫米/年），马来西亚半岛盆地的年降雨量趋势最小（1.21 毫米/年）。这些发现可以极大地促进该地区的气候变化监测，并可以帮助农业、城市规划和灾害管理等部门的决策者。