2. Trend analysis of total precipitation and extreme precipitation indices in Ben Tre province

Abstract

Climate change is increasing rainfall variability and extreme precipitation events, posing significant pressure on water resources and natural disaster risks in the coastal provinces of the Mekong delta. This study presents the results of a trend analysis of rainfall and extreme precipitation in Ben Tre province over the period 1978 - 2021, based on rainfall data collected from six gauging stations. The non-parametric Mann - Kendall test, combined with Sen’s slope estimator, was used for trend analysis, while extreme precipitation indices were applied to identify extreme events. The results indicate that total annual rainfall at most stations in Ben Tre province exhibits a decreasing trend. Huong My station recorded the most significant decline, with a Sen’s slope coefficient of -15 mm/year, achieving statistical significance. Total rainfall during the rainy season shows a downward trend, whereas dry season rainfall tends to increase slightly but lacks statistical significance. Intensity and frequency indices for heavy rainfall (Rx1day, Rx5day, R50 mm) show an increasing trend at the Huong My and Binh Dai stations. The CDD (Consecutive Dry Days) index at these stations primarily fluctuated between 2 and 3 days, while the CWD (Consecutive Wet Days) index ranged from 8 to 9 days. These findings provide a scientific foundation for drainage planning, water storage regulation, seasonal crop scheduling, and the development of climate change adaptation solutions for Ben Tre province.