Passive Microwave Radiometry for River Flow and Lake Monitoring in the Lower Mekong River Basin

The Mekong Basin’s rapidly growing population and changing water infrastructure (e.g., dams and canals) requires major improvements in observations of river discharge and reservoir storage changes. Floods and droughts can affect food supplies, requiring frequent and long-term observations for evaluation. We use satellite passive microwave radiometry (PMR) to monitor rivers and reservoirs, and compare performance at different frequencies and polarization combinations. PMR from TRMM, AMSR-E, AMSR2, GPM, SMOS, and SMAP sensitively monitors water surface area change at selected satellite gauging reaches (SGRs). These reaches can be measured globally at daily or near-daily intervals from 1998 to present. Rating curves that translate PMR signal to stage and discharge units can be obtained from nearby gauging stations (even if now discontinued) or from hydrologic modeling. We demonstrate the PMR capability to measure river stage/discharge/runoff and lake/reservoir water level as verified with in-situ gauging data for selected locations in the Lower Mekong Basin.