Purpose

This study aims to investigate aspects related to the changing trends of the rainfall extremes in the entire Mekong Delta in the period of 32 years (1984-2015) applying rainfall extreme indices. First, the homogeneity tests were applied to assess the quality of observed rainfall data series. The authors, then, investigated three rainfall indices including the number of very heavy rainfall days 20 mm (R20), number of days above 50 mm (R50) and number of days above 100 mm (R100) applying the Mann-Kendall test and Sen’s slope estimate.

Design/methodology/approach

First, the homogeneity tests were applied to assess the quality of observed rainfall data series. The authors, then, investigated three rainfall indices including the number of very heavy rainfall days 20 mm (R20), number of days above 50 mm (R50) and number of days above 100 mm (R100) applying the Mann-Kendall test and Sen’s slope estimate.

Findings

The results of R20 pointed out that an insignificant upward tendency was found in the coastal provinces, whereas an insignificant downward tendency was also recorded in the inland provinces. Regarding the number of R50, a similar trend to R20 was recorded with five stations slightly increased and five stations slightly decreased. For the number of R100, the results recorded an absence of significant trends over the entire study area. Approximately 58.5% of stations show a slightly decreasing trend, while 41.5% of the remaining stations recorded a slightly increasing trend.

Originality/value

For the number of R100, the results recorded an absence of the significant trends over the entire study area. Approximately 58.5% of stations show a slightly decreasing trend, while 41.5% of the remaining stations recorded a slightly increasing trend. Of note is the fact that the number of R100 occurred more frequently in the northern provinces, which means the northern region is facing a high risk of flooding.

中文翻译：

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气候变化影响下的湄公河三角洲极端降雨趋势

目的

这项研究旨在利用降雨极端指数来调查与整个湄公河三角洲在32年（1984-2015年）内的极端降雨变化趋势有关的方面。首先，均质性测试用于评估观测降雨数据序列的质量。然后，作者使用Mann-Kendall检验和Sen's检验了三种降雨指数，包括20 mm（R20）的超强降雨天数，50 mm（R50）以上的超天数和100 mm（R100）以上的超日数。斜率估算。

设计/方法/方法

首先，均质性测试用于评估观测降雨数据序列的质量。然后，作者使用Mann-Kendall检验和Sen's检验了三种降雨指数，包括20 mm（R20）的超强降雨天数，50 mm（R50）以上的超天数和100 mm（R100）以上的超日数。斜率估算。

发现

R20的结果指出，沿海省份的上升趋势微不足道，而内陆省份的下降趋势微不足道。关于R50的数量，记录了与R20类似的趋势，五个站点略有增加，五个站点略有减少。对于R100的数量，结果记录了整个研究区域中没有明显的趋势。大约58.5％的台站显示略有下降的趋势，而其余41.5％的台站显示出略有上升的趋势。

创意/价值

对于R100的数量，结果记录了整个研究区域中没有明显的趋势。大约58.5％的台站显示略有下降的趋势，而其余41.5％的台站显示出略有上升的趋势。值得注意的是，R100的数量在北部省份发生的频率更高，这意味着北部地区面临洪水的高风险。