HUMAN IMPACTS ON HYDROLOGICAL CHANGES IN THE MEKONG BASIN IN THAILAND AND VIETNAM

บทคัดย่อ

The Mekong River basin comprises the most significant rivers in Southeast Asia, including China, Myanmar, Lao PDR, Thailand, Cambodia, and Vietnam. The cascade of hydropower dams drastically affects the river's natural hydrology, limiting downstream flow and trapping crucial nutrients. Mega-dams (since 2010-2020), including those in China, Lao PDR, and Cambodia, have been constructed along the river. Thailand and Vietnam in the Mekong River basin, on the other hand, provide a fascinating case study due to the lack of dam development. The objective of this review study was, therefore, to explore socio-hydrological impacts on the Mekong River basin in Thailand and Vietnam. Monthly river discharge and water level changes in the Mekong River basin were obtained from the Mekong River Commission’s readings from 1960 to 2020, which were analyzed for the link among population density, poverty level, and the drought of 2019-2020. The reports indicated that the dams, including Xiaowan and Nuozhadu, significantly impacted water levels and river discharge, with data from 1960 to 2020 showing an increase in river discharge of up to 98% during the dry season and a decrease of up to -35% during the wet season. In addition, Chinese interests planned to extend navigation beyond Chiang Saen to Luang Prabang by removing the Khon Pi Luang rapids. This change in hydrology has destroyed fish habitats and migration patterns in the Mekong River, negatively affecting the productivity of fisheries for people living along the riverbanks, and is also linked to poverty levels; specifically, low population density correlates with low poverty levels, while high population density is associated with high poverty levels. The construction of mega-dams along the Mekong River may signal an alternative to the river's natural flow, influencing seasonal patterns and downstream ecosystems in Thailand and Vietnam.