How big is the Amazon?
Fresh water is a basic requirement for life, yet surprisingly, our knowledge of the volume and fluxes of water on floodplains and in rivers is poor. This is especially true outside of industrialized regions. Given this paucity of data, floodplain hydrology and flow hydraulics research are critical for understanding climate, biogeochemical fluxes, wetlands ecology, flood hazards, and water resource management. For example, the exchange of water between a river and its floodplain governs nutrient and sediment delivery necessary for ecological habitats whereas the vast floodplain water surface provides for both evaporation and CO2 evasion. Recent developments in satellite remote sensing promise more accurate monitoring of freshwater resources and better prediction of floods and droughts. Because of its size, the Amazon floodplain is a primary target. The GRACE satellite system provides a coarse, 3 degree by 3 degree spatial assessment of the volume on and flux of water through the floodplain at 15-day intervals. At a finer spatial resolution, our interferometric SAR measurements show that temporal changes in flood water heights (dh/dt) are more complex than typically assumed, and the water flows are not easily prescribed by discharge down the main channel and floodplain topography alone. Two-dimensional measurements of floodwater elevations and changes (dh/dt, and slope, dh/dx) are not routinely available, yet are critical to understanding the role of floodplains and wetlands in mitigating flood hazards, controlling biogeochemical cycles and promoting biodiversity. Thus, an international team is proposing the Surface Water Ocean Topography (SWOT aka WATER HM) satellite to routinely map the ever changing distribution of the world's water. Ohio State University through its Climate, Water, and Carbon Program is a partner in SWOT research and development.
Contact: Doug Alsdorf