Spatial evolution of land use and land cover for the Tatu-Bola Wildlife Refuge - Pernambuco, using orbital images

Abstract

This article aims the analyze NDVI (Normalized Difference Vegetation Index), NDWI (Normalized Difference Water Index), and NDBI (Normalized Difference Built-up Index) radiometric indices for TM and OLI sensor scenes aboard the LANDSAT satellite. The study area is the Tatu-Bola Wildlife Refuge, created in March 2015 through State Decree number 41,546, and its surroundings. The study aimed to monitor the spatial and temporal evolution of land use and land cover in a period before and after the implementation of the Armadillo-Bola Wildlife Refuge, using indices of vegetation (NDVI), moisture (NDWI), and exposed soil (NDBI) and its relationship with the surroundings. TM and OLI images (orbit and point 217-066) were used on board the LANDSAT satellite 5 (23-05-1987, 15-05-1996, and 01-02-2005) and 8 (28-01-2015 and 17- 03-2021), radiometrically and geometrically corrected and obtained by accessing EarthExplorer, with the calculation of radiance and reflectance being performed, and the indices applied. In order to better identify the area with vegetation and exposed soil, the RGB composition was performed, with NDBI, NDVI, and NDWI indices for Landsat images and fusion of multispectral and panchromatic bands in WPM sensor images from the CBERS-4A satellite from 23- 08-2020 (orbit and point 198-124) and 18-09-2020 (199-124). Digital numbers of cloud and shadow pixels were excluded through supervised classification. Between 1987 and 2021, it was possible to observe a decrease in vegetation cover, especially around the RVS Armadillo-balla, and an increase in area, with NDVI values lower than 0.40. The Refuge area in Petrolina has the largest amount of deforested area. The use of RGB composition of the indices and the merged images from the CBERS-4A satellite, with a spatial resolution of 2 m, present a significant improvement in identifying areas of exposed soil and dry vegetation.