Category: Irrigation and Drainage


Tuesday, Jun 5
8:30 AM – 5:30 PM

Evapotranspiration is a key process of hydrological cycle and a sole term that links land surface water and energy balances. Its estimation provides useful information for several applications in water resources and agriculture management. Since the direct estimative of evapotranspiration is very difficult, there are several alternative models for representing this process. However, implementing these models in a consistent manner is difficult due to the large information requirements and data uncertainty. In this light, evapotranspiration assessment becomes a challenge especially in Brazil and other developing countries, where meteorological data are normally absent. To overcome this problem, simplified empirical methods for calculating evapotranspiration are widely used in order to generate inputs for hydrological models. However, even these models require a minimum monitoring that is usually not available and should be validated before its implementation for a specific location. Therefore, the main goal of this study was to evaluate Penman–Monteith (PM), Priestley-Taylor (PT) and seven simplified empirical methods to estimate reference evapotranspiration in ungagged basins based on two distinct approaches. The first approach replaced missing data by climatological and FAO56 suggestions and, the second one, used data from ERA-INTERIM reanalysis to estimate missing values. The results showed that filling data in the original PM and PT methods brings better results than using the empirical formulas and ERA-INTERIM’s data has a large potential to overcame data limitations.

Co-Authors: Pedro Ferreira, Santa Maria - Brazil – University of Santa Maria; Rutineia Tassi, Santa Maria - Brazil – University of Santa Maria

Daniel GUSTAVO.. Allasia

University of Santa Maria
Santa Maria - RS, Rio Grande do Sul, Brazil

Jessica Ribeiro Fontoura

Graduate research student
University of Santa Maria
Santa Maria, Rio Grande do Sul, Brazil