Soil moisture and its applications in the Mekong River Basin

Surface soil moisture is an important variable in studies related to the environment, affecting the water-energy nexus through land-atmospheric interactions. However, collecting soil moisture data is challenging due to the lack of ground-truth observations, highlighted in many studies. This issue is particularly prominent in the Mekong River Basin (MRB), Southeast Asia, where it has been indicated as a major task to solve in recent years. Over various proposed solutions, using remote sensing-based products is considered relatively reliable for capturing the spatial and temporal variations of this variable. Notably, recent advancements in satellite remote sensing technology have helped improve the performance of current remote sensing products. In this chapter, we aim to provide a comprehensive overview of the developments in remote sensing-based soil moisture in the MRB and its neighboring regions, mainly focusing on: (1) a review of current and near-future soil moisture products; (2) common soil moisture-derived techniques along with their strengths and weaknesses; and (3) evaluations of soil moisture and its applications in environmental-related studies. Our fundamental objective is to provide a general understanding of this variable and its current, common uses that could be applied to studies in the MRB. This could thus support stakeholders and decision-makers in planning sustainable strategies in this region for local and regional development.