Investigation of precipitation trends in Lower Mekong Delta River Basin of Vietnam by innovative trend analysis methods

Abstract

Precipitation is a crucial hydro-meteorological variable for the protection and sustainability of water resources, and it has been significantly affected by climate change. Hence, it is essential to evaluate the effects of climate change on precipitation for effective water resource planning and development. This study aimed to evaluate trends of monthly precipitation in the Lower Mekong Delta River Basin (LMDRB) in southern Vietnam using innovative trend analysis methods. Monthly total precipitation data of eight stations in the basin observed from 1989 to 2018 were used. Mann-Kendall (MK) test, Innovative Polygon Trend Analysis (IPTA), and Improved Visualization of Innovative Trend Analyses (IV-ITA) methods were applied after homogeneity tests to the time series of the stations determined to be homogeneous. The IPTA method examined possible monthly precipitation transitions and seasonal changes, while the IV-ITA method examined the trend of the low and high precipitation categories. The IPTA method was more sensitive than the MK Test method in trend detection as it detected a trend in 85% (approximately 50% increase and 35% decrease) of the 84 (12*7) months. In almost all stations, an increasing trend was observed in September and December at low values, while a significant decrease was observed in April at high values. Continued increases and decreases in precipitation due to climate change impacts will significantly affect rice production in the LMDRB. This study provides valuable insights into the impact of climate change on precipitation in the basin, which could help in effective water resource planning and development.