Abstract

TREZZA, Ricardo. Evapotranspiration from a remote sensing model for water mngement in an irrigtion system in Venezuela. INCI [online]. 2006, vol.31, n.6, pp.417-423. ISSN 0378-1844.

This paper explores the feasibility of the use of an energy balance model for the estimation of evapotranspiration from satellite data in a large irrigated area, the Río Guárico irrigation system, in Venezuela. A large water reservoir stores the water coming from the Guárico River and provides for irrigation of ~60,000ha. Rice is the main crop grown in the area. Despite water availability, the agricultural potential of the area has been limited by lack of appropriate water management and distribution. The satellite-based energy balance model used in this study was SEBAL (Surface Energy Balance Algorithm for Land), an image-processing model for calculating evapotranspiration (ET) as a residual of the surface energy balance, developed in the Netherlands, that has been applied in many developing countries. SEBAL uses satellite data collected by the LANDSAT Thematic Mapper (TM) or other satellite sensors collecting visible, near-infrared and thermal infrared radiation. The main advantage of SEBAL is the need of a minimum amount of ground data. The original model was modified and adapted for use with the specific conditions of the study area in Venezuela, using the FAO-56 methodology. The results suggest that SEBAL can be considered as an operational and feasible method to predict actual ET from irrigated lands having limited amount of ground information, which is a common situation in Venezuela.

Keywords : Evapotranspiration; Energy Balance; Irrigation; Satellites.