Assessment of desertification in the brazilian semiarid region using time series of climatic and biophysical variables

Abstract

The municipality of Irauçuba, located in the Semiarid region of Ceará, Brazil, has faced the effects of desertification resulting from the scarcity of rainfall. This study aimed to assess the progression of desertification in the area from 2003 to 2020, using climatic and biophysical data collected during this period. We used supplementary data from automatic meteorological stations operated by the National Agency of Water and Basic Sanitation to determine the rainfall anomaly index of the historical series. Additionally, we performed annual scale validation of the CHIRPS data using statistical indicators such as Pearson Correlation Coefficient, Mean Error, Percentage BIAS, and Root Mean Square Error. Subsequently, we analyzed land cover and land use changes over the 17 years (2003-2020) in the municipality by processing CHIRPS, MODIS product (MOD16A2 and MOD11A2), and MapBiomas data in the Google Earth Engine digital platform and QGIS software. We analyzed land cover and land use changes using MapBiomas data. Finally, we analyzed the aridity index for the same 17-year period. The research findings revealed a significant correlation between rainfall and biophysical parameters, with the lowest aridity index of 0.255 observed between 2012 and 2014 and the highest of 0.464 between 2018 and 2020. The area's susceptibility to the desertification process was classified as high, which is consistent with the Semiarid climate of the region. The methodology employed during the research proved to be a sustainable technology of low economic cost and telling and easy access, which enabled the creation of a scientific contribution for future works in the region, besides being able to add knowledge for studies of environmental degradation.