Mekong River dry season changes due to hydropower dams and extractive processes: Making sense of contradictory community observations in Thailand, Laos and Cambodia

The Mekong is amongst the most important rivers in the world with regard to biodiversity and livelihood. Over the last few decades, however, the river has experienced dramatic hydrological changes, mainly due to the construction of large hydropower dams on the mainstream Mekong and its tributaries. Other potentially crucial factors include sand mining, erosion, embankment construction, and water extraction. In March and early April of 2024, we organised focus group interviews to discuss the changes that have occurred during the dry season with local people living in different communities along the mainstream Mekong River: 32 villages in eight provinces in northern and northeastern Thailand, 9 villages in Champassak Province, southern Laos, and 3 villages in Stung Treng Province, northeastern Cambodia. In this paper, we present some of the results of this research, particularly focusing on water level and turbidity changes, as local people along the Mekong River have varied understandings regarding whether there is more or less water in the Mekong River during the dry season. We argue that riverbed incision resulting largely from hydropower dam development and sand mining have, in particular, led many people living along the Mekong between northeastern Thailand and central Laos to incorrectly believe that there is less water in the Mekong River during the dry season compared to the past, while dry season water releases from upriver hydropower dams have led those in northern Thailand, lower northeastern Thailand, southern Laos, and northeastern Cambodia to assess that there is now more water in the Mekong River.