Use of vegetation index and surface temperature to estimate soil moisture in a semi-arid catchment in Brazil with limited monitoring

Wednesday, 17 December 2014
Tainá Martins Cunha1, Vitor Paiva Alcoforado Rebello1, Otto Correa Rotunno Filho1, Maria Claudia Barbosa1, Mariza Ramalho Franklin2 and Venkataraman Lakshmi3, (1)UFRJ Federal University of Rio de Janeiro, Rio De Janeiro, Brazil, (2)Institute for Radiation Protection and Dosimetry, Rio de Janeiro, Brazil, (3)Univ South Carolina, Columbia, SC, United States
During the last two decades, there have been numerous studies using remote sensing to study catchment energy and water balance. A well-known example is the combination of surface temperature (Ts) and the normalized difference vegetation index (NDVI), which can provide information on vegetation and moisture conditions at the land surface. Since the soil moisture is a key variable in hydrological modeling, this information is potentially useful in large watersheds and remote areas in developing countries, where little infrastructure and few resources still make continuous in-situ monitoring of environmental variables a difficult task, as well as in semi arid areas, where the lack of water may represent an obstacle to the regional economic and sustainable development. The basic methodology is to calculate soil moisture indexes by the scatter plots of NDVI and Ts and to analyze the Ts/NDVI slope, in order to estimate temporal patterns of soil moisture. We will utilize the standard vegetation index and surface temperature products from MODIS and NOAA – AVHRR, and the results will be compared with soil moisture derived from a hydrological model (Soil Moisture Accounting Procedure). This work will focus on a 18200 km² semi-arid catchment in Northeastern Brazil.