Avaliação de parâmetros biofísicos em anos seco, normal e chuvoso da bacia hidrográfica do riacho Exu no sertão de Pernambuco a partir de sensoriamento remoto

Abstract

Increasingly, we seek to investigate anthropic actions and their relationship with land use and occupation. The use of satellite images through remote sensing and the formulation of algorithms used in the modeling of biophysical parameters enable studies on meteorological phenomena, land use and occupation. There is a need to better understand and interpret the scales of rainfall variability as well as extreme events of droughts and humidity, so in this way, the monitoring of these extremes can be done through the use of vegetation indexes. The streamlet basin Exu is located in the city of Serra Talhada, semi-arid region of Pernambuco, where water scarcity is a present problem, being a fundamental unit to support planning with respect to natural resources. The present study aimed to identify years with extreme events to the precipitation of a series of 31 years (1986-2016) using quantis technique, index of rainfall anomalies and also to analyze biophysical data for the same series of years using orbital images of Landsat 5 - TM and Landsat 8 - OLI / TIRS. The biophysical parameters albedo of the surface, NDVI, SAVI, IAF and surface temperature were elaborated through the SEBAL algorithm implemented in ERDAS IMAGINE 9.1 software in the Model Maker tool. The images used went through atmospheric correction using the DOS method in QGIS 2. 18.9 software using the Semi-Automatic Classification Plugin. Of the 31 years evaluated by the technique of quantiles only 3 were classified as "Rainy", 19 as "Normal" and 9 years classified as "Dry". In the data evaluated using the Index of Rainfall Anomalies it was observed 16 years with positive indexes ranging from 0.47 to 8.24 and 15 years with negative deviations ranging from -0.32 to -7.17. The biophysical parameters of dry season images showed higher values of albedo and surface temperature compared to rainy season images, which in turn had higher values of vegetation index. It is concluded that the RAI and quantiles are relevant tools for classification and evaluation of rainfall variability while the analysis of the biophysical parameters of the surface albedo, NDVI, SAVI, IAF and surface temperature by means of the SEBAL allowed to evaluate effectively the spatial-temporal dynamics on the surface of the basin.