Evaluation of evaporation methods for modelling rainfall interception in a dry tropical forest

Abstract

The simulation of rainfall interception by vegetation is essential to water resource management, considering both changing land use and climate change effects. In the rainfall interception models, the evaporation rate is frequently estimated by means of the Penman-Monteith method, but the Priestley-Taylor equation appears as a promising approach with fewer input requirements. In this study these both formulations were evaluated with the sparse Gash model with variable parametrization for estimating rainfall interception by four tree species in a Brazilian dry tropical forest. The Penman-Monteith equation was used with the canopy resistance set to zero, and the momentum method was applied for estimating the aerodynamic resistance. The Priestley-Taylor formulation was tested with the proportional coefficients (α) of 1.26 and 1.34. The results of rainfall predictions were compared with the measurements by statistical indicators, which pointed slightly favorable to Penman-Monteith method. The Priestley-Taylor with α = 1.26 resulted in predictions better than with α = 1.34. Most of the simulations were classified as good (CMRE varying from 5.5 − 9.3%). The Priestley-Taylor method can be used for estimating the evaporation rate in simulations based on the sparse Gash model with variable parametrization in the studied dry tropical forest, under situations with restrictions of micrometeorological measurements or minimal processing time requirement.