Spatial and temporal distribution of soil moisture using remote sensing techniques

Abstract

The determination of soil moisture distribution is complex and timely, making it unable to describe the behavior of its spatial and temporal distribution on a regional scale. The objective of this study was to estimate and evaluate the spatial and temporal variability of soil moisture by means of the instantaneous evaporative fraction in the semi-arid region using remote sensing data. Three images of the Landsat 5 sensor satellite TM were used on September 21, 2008, June 20, 2009 and August 29, 2011, covering the area of study: Iguatu, Brazilian semiarid. These images were processed from the ERDAS imagine 9.1 software, where the radiometric calibration and the conversion to radiance and reflectance were performed through complementary surface data using the SEBAL algorithm. The thematic maps of the energy balance biophysical parameters: instantaneous evaporative fraction (FE) and the degree of soil moisture saturation (θ / θsat) were processed by ArcGis® 10.2.2 software. The descriptive statistics was used to determine the differences of FE and θ / θsat in relation to the anthropological actions and the local climate of the region. Therefore, the monitoring of these biophysical parameters, especially the degree of soil moisture saturation, showed to be an effective part of the energy balance, configuring before them the power to make decisions regarding environmental aspects. The estimation of the spatial pattern of the degree of soil moisture saturation presented consistent values for the different uses and occupations of the soil, showing a great relation with the values of the evaporative fraction in all the images studied.