Análises geoespaciais da dinâmica das secas vegetativas na bacia do Alto Rio Paraíba-PB entre 2001 e 2017

Abstract

Drought is a very complex natural phenomenon that affects water supply and consequently impacts on agricultural and socioeconomic activities, causing social and political crises. This phenomenon is one of the most important factors that cause degradation in vegetation. Determining areas with more drought sensitive vegetation can be effective in managing drought risk. Thus, different indices based on remote sensing products have been used to evaluate the impacts of drought on vegetation. Thus, this study used drought indices based on data from the MODIS sensor on the TERRA-AQUA satellites, referring to the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) to estimate the Vegetation Supply Water Index (VSWI) indices and Vegetation Health Index (VHI) and analyze vegetative droughts. This study also used rainfall data from the Tropical Rainfall Measuring Mission (TRMM) to estimate Rain Anomaly Index (IAC) and to characterize the rainfall regime in the Upper Paraíba River basin for the period 2001-2017 and to characterize spatiotemporally. The vegetative droughts in the basin. In this sense, the objective of this study is to analyze spatially and temporarily the droughts and their impact on the vegetation cover of the Upper Paraíba River basin. The IAC results showed the dry and wet periods of the basin and were classified according to their intensities. Thus, from 2001 to 2017, the IAC defined the occurrence of extreme droughts in 2012 and 2015, as well as an extremely wet year in 2009. The dry and wet periods that occurred with different intensities were used to analyze the impact in the vegetation. With the estimated values of VSWI and VHI to analyze the vegetative droughts, it was observed for the years of higher humidity and drought spatial and temporal conditions of different droughts. These rates ranged from 0 to> 40 for the basin, where values closer to or> 40 indicated normal humidity conditions for the vegetation, and therefore no water stress, and values close to zero indicated extreme drought conditions in the basin vegetation. Based on estimates of vegetative drought based on VSWI and VHI, VSWI showed better drought in the basin, as it reflected the decrease in vegetation vigor (NDVI) and the increase in surface temperature (LST) to indicate drought and vegetation did not underestimate vegetation with lower water stress as occurred in VHI estimates.