Use of the Geographic Information System and remote sensing data for the estimation of real evapotranspiration at a regional scale

The present study had a general purpose to establish the possibility for mapping on a regional scale the actual evapotranspiration (ETR) in the Tunis region using remote sensing and mapping data. It relied on Landsat and SPOT image processing to obtain land-use cover. NOAA-AVHRR data was used to estimate surface temperature. Atmospheric and geometric correction must be used in order to transform the measured radiance levels into surface temperature, albedo and vegetation index. Moreover, thematic data was obtained from satellite images and related with multisource data (e.g. geographical and meteorological data) within a GIS. The authors tried to validate an ETR estimation method using remote sensing in soil measures. A comparison was made between ETR calculated from satellite-derived surface temperature and field measurement. These analyses have shown that the estimates of the ETR obtained from remote sensing are sufficiently accurate to be used for the monitoring of the water budget of the superficial layer of the soil.