Climate change and its impact on water availability of large international rivers over the mainland Southeast Asia

Abstract

Changes in climate and the resulting hydrologic variability are of great concern in international river basins. Based on observed station data, climate change and its impact on water availability in large international rivers across mainland Southeast Asia (MSA) were investigated by a combined method of trend detection and hydrologic budget balance analysis. This method can be applied easily to other studies to evaluate impacts of climate change on run‐off and water resources at the basin scale. Precipitation showed a decreasing trend in the MSA during 1960–2016, especially in the dry season. Decreasing precipitation and increasing evapotranspiration were the main reasons for severe droughts during recent years. Climate change was the main reason for run‐off changes over the MSA. The presence of dams in the upstream region was not enough to change the annual variability of natural run‐off in the Mekong River. Run‐off and precipitation changes showed significant variances in different basins and regions, and in different periods. The overall trend of precipitation and run‐off showed a periodicity of about 35 years. Nonprecipitation effects were also significant in some regions, including increasing irrigation water demand in the Red River and increasing glacial melt in the Brahmaputra River basin. Melt increased at least 75.2 × 108 m3/10a during 1960–2003, representing 1.2% of mean annual run‐off in the Brahmaputra River. The positive effect of glacial meltwater was almost equal to the negative effect of evapotranspiration on run‐off change in the Lancang River. Increasing evapotranspiration played a dominant effect on run‐off changes in the Yarlung Zangbo River basin during 1960–2010.

Assessing the Effect of Incorporating Environmental Water Requirement in the Water Stress Index for Thailand

“…The potential effect of climate change on the availability of water in the future, especially in the wet season which could potentially have less rainfall, should be considered in the long-term plans on water resource management and agriculture. This is the same as other studies on the impact of climate change on water availability which revealed that the impact of climate change becomes a significant factor influencing changes in precipitation and temperature [9,22,23]. Although the levels of water stress in some watersheds increase due to less rainfall, their environmental water is already safeguarded as the first priority is given to the environmental water in the WSI e2 approach.…”

Nonmonsoon Precipitation Dominates Groundwater Recharge Beneath a Monsoon‐Affected Glacier in Tibetan Plateau

“…Furthermore, the seasonal difference of groundwater recharge fluxes/rates may modify groundwater and surface water quality by influencing overland flow, erosion, and solute transport through subglacial soil/rocks (Jasechko et al, ; Vincent et al, ). A great amount of studies on climate change from 1960 to 2010 in the SETP has been carried out with the conclusions that (1) the annual average temperature and all the seasonal temperature increases with the maximum increasing in winter (Fan & He, ; Su et al, ) and (2) the annual precipitation changes little with significant increase in spring (Liu et al, ; Lutz et al, ). In response to the climate change, our study implies that more groundwater recharge during the nonmonsoon seasons could be expectedly induced by increased ice‐melt water and spring precipitation.…”

Hydro-Meteorological Trends in the Yarlung Zangbo River Basin and Possible Associations with Large-Scale Circulation

“…Although studies for investigating the hydro-meteorological changes over the YLZR basin are available in the literature, few can be found for exploring the trends of the runoff associated with large-scale circulation. Changes in regional air temperature have considerable impacts on the snow cover and glaciers within the YLZR basin [32][33][34], which in turn affects the water resources of the basin [30]. In recent decades, the air temperature within the YLZR basin has shown a significant trend of increase [16].…”