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University of Nebraska – Lincoln (2019)

Drought Impacts Assessment in Brazil - A Remote Sensing Approach

Mariano, Denis Araujo

Titre : Drought Impacts Assessment in Brazil - A Remote Sensing Approach

Auteur : Mariano, Denis Araujo

Université de soutenance : University of Nebraska – Lincoln

Grade : Doctor of Philosophy (PhD) 2019

Résumé
Climate extremes are becoming more frequent in Brazil ; studies project an increase in drought occurrences in many regions of the country. In the south, drought events lead to crop yield losses affecting the value chain and, therefore, the local economy. In the northeast, extended periods of drought lead to potential land degradation, affecting the livelihood and hindering local development. In the southern Amazon, an area that experienced intense land use change (LUC) in the last, the impacts are even more complex, ranging from crop yield loss and forest resilience loss, affecting ecosystem health and putting a threat on the native population traditional way of living. In the studies here we analyzed the drought impacts in these regions during the 2000s, which vary in nature and outcomes. We addressed some of the key problems in each of the three regions : i) for the southern agriculture, we tackled the problem of predicting soybean yield based on within-season remote sensing (RS) data, ii) in the northeast we mapped areas presenting trends of land degradation in the wake of an extended drought and, iii) in southern Amazon, we characterized a complex degradation cycle encompassing LUC, fire occurrence, forest resilience loss, carbon balance, and the interconnectedness of these factors impacting the local climate. The studies integrated RS data of evapotranspiration, temperature, precipitation, soil moisture, albedo, and biomass-related indicators. Official data for population and agricultural statistics were also utilized to better connect climate extremes to human factors. Our results indicate that crop yield in southern Brazil can be predicted using RS data and therefore, provide valuable information for decision-makers in the agriculture value chain. In the northeast, extended drought associated with anthropogenic pressure for resources represent a threat to the ecosystem health by affecting soil and water quality, micrometeorological conditions and, thus, people’s livelihood. Finally, in southern Amazon, the LUC led to a regional LD which has positive feedback on the climate, causing even more damage as the degradation cycle advances, putting a threat on the local agriculture economic sustainability.

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