Water Resource Availability and Use in Mainland Southeast Asia

This chapter assesses water resource availability and use in the five countries in Mainland Southeast Asia (MSEA): Myanmar, Thailand, Laos, Cambodia, Vietnam. The total water resources in the region are estimated using a wide range of hydrometeorological data. Results show that the average annual runoff is about 1941.1 billion m³ in the region. Regarding spatial differences, rainfall and runoff in the southern coastal areas are generally higher than the ones in the central and northern inland areas, and the western coastal areas have more rainfall than the eastern coastal areas. Moreover, results indicate that the overall utilization rate of water resources in the region reached 9%, mainly used for hydropower development, agricultural irrigation, fishery and aquaculture, shipping and other aspects. Agriculture was the primary water user (about 92.2%) in the study area compared to industrial (about 3.6%) and domestic (about 4.2%) water users. The region is divided into different water resource zones, including 7 first-level water resources zones, 17 s-level water resources zones, and 138 third-level water resources zones. The division is done by considering the hydrology conditions, natural landforms, administrative divisions, and river systems in the study area. Particularly, results show that the seven firstlevel water resources regions are all transboundary basins, implying that the water resources management in the region needs the solid cooperation and overall planning of all countries. Results show that the total water demand in MSEA will reach 200, 208, and 225 billion m³ in 2025, 2030, and 2040, respectively. The prediction is obtained using the historical social and economic data. Social-economic developments are predicted to estimate the future water consumption. will assure a balance between the supply and demand of water resources in the study area, with asurplus of water resources supply ability.