Extreme rainfall trends over the Mekong Delta under the impacts of climate change

Abstract

<jats:sec> <jats:title content-type="abstract-subheading">Purpose</jats:title> <jats:p>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.</jats:p> </jats:sec> <jats:sec> <jats:title content-type="abstract-subheading">Design/methodology/approach</jats:title> <jats:p>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.</jats:p> </jats:sec> <jats:sec> <jats:title content-type="abstract-subheading">Findings</jats:title> <jats:p>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.</jats:p> </jats:sec> <jats:sec> <jats:title content-type="abstract-subheading">Originality/value</jats:title> <jats:p>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.</jats:p> </jats:sec>

Shifting crop planting calendar as a climate change adaptation solution for rice cultivation region in the Long Xuyen Quadrilateral of Vietnam

“…In the Long Xuyen Quadrilateral, rice is broadcasted in the paddies from two to three cropping seasons per year depending on the topographic conditions, irrigation water and local precipitation. The weather condition is consistent for planting rice crops with daily sunshine reach up to 6.3 h, air temperature varies from 27 to 29 °C, mean air humidity reach about 80% and mean annual precipitation reach approximately 1700 mm yr -1 (Vu et al, 2018;Lee and Dang, 2020). Rainy season often lasts from mid-May to late November and accounting for 85% of annual rainfall ( Figure 2).…”

“…In recent years, precipitation has strongly varied in many areas of the world (MNRE, 2016;Lee and Dang, 2019c), resulting in drought often appear in the dry season, flooding occur in the wet season (Asia Pacific Network, 2010;MNRE, 2016), and off-season precipitation leading to rice crop failure (Asia Pacific Network, 2010; Lee and Dang, 2020). Kotir (2011) stated that the potential risks for agriculture sector under the impacts of climate change (ICC) are attracting the attention of mankind in the 21 st century.…”

“…The rice paddies in the Long Xuyen Quadrilateral have faced drought, saline intrusion and off-season precipitation events over the last two decades, due to the ICC, resulting in crop yield decline (MNRE, 2016;Lee and Dang, 2020). Farmers must re-broadcast rice crops if a precipitation event with high intensity just occur after the seeds have broadcasted in the rice fields (Deb et al, 2016;Lee and Dang, 2020).…”

“…The rice paddies in the Long Xuyen Quadrilateral have faced drought, saline intrusion and off-season precipitation events over the last two decades, due to the ICC, resulting in crop yield decline (MNRE, 2016;Lee and Dang, 2020). Farmers must re-broadcast rice crops if a precipitation event with high intensity just occur after the seeds have broadcasted in the rice fields (Deb et al, 2016;Lee and Dang, 2020). Further, in the harvesting stage of the SA cropping season, heavy precipitation events with intensity reach up to 20 mm appear suddenly, resulting in the obtained crop yield to be strongly decreased (Asia Pacific Network, 2010;Deb et al, 2016).…”

Simulating rainfall IDF curve for flood warnings in the Ca Mau coastal area under the impacts of climate change

“…Rainfall is considered as one of the main factors of the hydrological cycle, which is closely related to human activities, especially in the agricultural sector (Al Saji et al, 2015;Lee and Dang, 2020).…”