Variabilidade e tendência espaço-temporal da caatinga utilizando o IVDN e precipitação pluvial relacionadas com a degradação ambiental no Semiárido brasileiro

Abstract

The objective of this study is to analyze variability and trend spatiotemporal Caatinga using the Normalized Difference Vegetation Index and rainfall related to environmental degradation in the Brazilian semiarid region. The SPOT data were used in the temporal resolution of 10 days and space of 1 kilometer, in the periods of 1998-2012 and 2007-2014. Also of rainfall data were used, with spatial resolution of 0,25º (10 days) and 0,05º (monthly) for the periods 1998-2012 and 1981-2014. The work was divided into two methodologies. The first methodology was based on analysis of vegetation dynamics trend, by correlating SDVI and SPI-1 indices for the period 1998 to 2012. The second methodology was the interannual analysis of vegetation for the period 2007 to 2012, correlating NDVI with rainfall for the same period, relating to drought risk index and sub-indices of socioeconomic bias. In the first methodology analysis, the correlation was positive in almost all SAB with better lags in the period of 3-6 months. The SDVI showed positive tendencies north and isolated areas of BSA, on the other hand the SPI-1 showed weak in some areas and positive and greater void part. In the decision tree stood out two areas north of the SAB with degradation trends and greening. In the analysis of the second method, the NDVI showed areas with signs of degradation in some areas of central and northeastern SAB. While the inter-correlation between NDVI and precipitation showed a distribution of positive and significant correlation that extended from the central region north of the SAB, while the negative correlation was further south. Relating the variables with the sub-indices of socioeconomic bias, precipitation and the NDVI had positive correlation at all likely levels with a high degree of correlation in the level 3 (high) observed for the three sub-indices. The trend methodology is suggestive for further analysis to contribute adding value to the new monitoring of degraded areas of technical assigning new data with better spatial and temporal resolution, as well as indicators in order to improve analysis and more efficient results.