A Look at Amazon Basin Seasonal Dynamics with the Biophysical ...

Long-term Simulations of Discharge and Floods in the Amazon BasinMichael T. Coe 1 , Marcos Heil Costa 2 , Aurélie Botta 1 , and Charon Birkett 31 Center for Sustainability and the Global Environment, Institute for EnvironmentalStudies, University of Wisconsin, 1710 University Ave., Madison, WI, 53706,mtcoe@wisc.edu2Federal University of Viçosa, Viçosa, MG, 36571-000, Brazil3ESSIC, University of Maryland at College Park, Mail Code 923, NASA/GSFC,Greenbelt, MD, 20771A terrestrial ecosystem model (IBIS) and a hydrological routing algorithm (HYDRA) areused in conjunction with long time-series climate data to simulate the river discharge andflooded area of the Amazon/Tocantins River Basin over the last 60 years. Evaluating theresults of this modeling exercise over the entire basin against land and satellite basedobservations yields three major results: (1) Observations at 121 stations throughout thebasin show that discharge is well simulated for most tributaries originating in Brazil.However, the discharge is consistently underestimated, by greater than 20%, fortributaries draining regions outside of Brazil and the main stem of the Amazon. Thedischarge underestimation is most likely a result of underestimated precipitation in thedata set used as model input. (2) A new flooding algorithm within HYDRA captures themagnitude and timing of the river height, and flooded area in relatively good agreementwith satellite based observations, particularly downstream of the confluence of the Negroand Solimões Rivers. (3) Climatic variability strongly impacts the hydrology of the basin.Specifically, we find that short (3-4 year) and long (28 year) modes of precipitationvariability drive spatial and temporal variability in river discharge and flooded areathroughout the Amazon/Tocantins River basins.