Drought Propagation in Brazilian Biomes Revealed by Remote Sensing

Drought events have been reported in all Brazilian regions every year, evolving slowly over time and large areas, and largely impacting agriculture, hydropower production, and water supplies. In the last two decades, major drought events have occurred over the country, such as the 2010 and 2015 events in the Amazon, the 2012 event in the Pampa, and the 2014 event in the Cerrado biome. This research aimed to understand drought propagation and patterns over these biomes through joint analysis of hydrological, climatic, and vegetation indices based on remote sensing data. To understand the drought cascade propagation patterns, we assessed precipitation, evapotranspiration, soil moisture (at surface and sub-surface), terrestrial water storage, land surface temperature, enhanced vegetation index, and gross primary productivity. Similar drought patterns were observed in the 2015 Amazon and 2012 Pampa droughts, with meteorological and agricultural droughts followed by a hydrological drought, while the 2014 event in the Cerrado was more associated with a hydrological drought. Moreover, the 2015 Amazon drought showed a different pattern than that of 2010, with higher anomalies in precipitation and lower anomalies in evapotranspiration. Thus, drought propagation behaves differently in distinct Brazilian biomes. Our results highlight that terrestrial water storage anomalies were able to represent the hydrological drought patterns over the country. Our findings reveal important aspects of drought propagation using remote sensing in a heterogenous country largely affected by such events.

Automated summary

This study analyzed remote sensing data on vegetation, climate, and hydrological indices to understand drought propagation and patterns in the Amazon, Pampa, and Cerrado biomes of Brazil. The findings showed that drought events in the Amazon and Pampa biomes followed a sequence of meteorological and agricultural droughts, while the Cerrado biome was primarily affected by hydrological drought. The 2015 Amazon drought exhibited different characteristics compared to the 2010 drought, with higher precipitation anomalies and lower evapotranspiration anomalies. Therefore, drought propagation varies across different Brazilian biomes.