Abstract
The Mekong River Basin is one of the largest transboundary basins in the world. It is bordered by six countries: China, Myanmar, Thailand, the Lao People's Democratic Republic, Cambodia, and Vietnam. The hydrology, agriculture, ecosystem, and other watershed functions are continuously changing as a result of various human activities carried out in the basin to fulfill expanding population demands for food, energy, and water. We illustrate how external stressors such as climate change and variability, land cover and land use change, soil moisture, evapotranspiration, and streamflow affect the spatial distribution of soil moisture, evapotranspiration, and streamflow. Furthermore, the hydrological regime of the Mekong is altered by numerous dams, and the impact on environmental flows (EFs) is unknown. Monitoring the quality, quantity, and duration of water flows is crucial for maintaining freshwater ecosystem species, functions, and resilience, as well as the livelihoods of human communities who rely on healthy ecosystems. Understanding the features of river flows requires remote sensing-based storage estimations for reservoirs and their function in boosting irrigation and hydropower output, in case in-situ gauge data is not available. In an integrated climate-hydrology-systems dynamics framework, techniques for quantifying fluxes, water budget, sediments, salinity, and nutrients in this largely managed basin are described. Model and remote-sensing-based spatial estimates of evapotranspiration and soil moisture are addressed. The challenges identified by several ongoing studies, as well as solutions for better water resources management, are broadly discussed.
