Sensitivity of pasture soil moisture and evapotranspiration to drought in the Brazilian Amazon

Authors: Trent Biggs*, San Diego State University, Emily Deardorff, San Diego State University, Rina Cao, University City High School, San Diego, CA, Fernando de Sales, San Diego State University
Topics: Water Resources and Hydrology, Climatology and Meteorology, Spatial Analysis & Modeling
Keywords: evapotranspiration, pasture, Amazon, climate
Session Type: Virtual Paper
Presentation File: No File Uploaded


The Amazon basin has experienced droughts of increasing frequency and magnitude, but the impact of drought on soil moisture and evapotranspiration (ET) in pastures has not been thoroughly documented. Here, we apply a 1-D ecophysiological model (Brook90) forced by reanalysis climate data (GLDAS) to quantify the impact of drought on soil moisture and ET in pastures of the State of Rondonia in the Brazilian Amazon. Brook90 is calibrated to observations at a single location, and then used to quantify ET in pastures on various soil types in years of both normal precipitation, and during the droughts of 2005, 2010, and 2015. Modelled ET is compared with both normalized difference vegetation index (NDVI) and ET from satellite products (MOD16 and others). The findings underscore the importance of dry season precipitation and soil type on soil moisture status, and suggest that droughts adversely impact agricultural production in the Amazon.

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