ANÁLISE EXPERIMENTAL E VALIDAÇÃO DE CURVAS BIMODAIS DE RETENÇÃO DE ÁGUA NO SOLO PARA SOLOS ARENO-ARGILOSOS RESIDUAIS DA FORMAÇÃO ITAQUERI EM SÃO CARLOS – SP

Experimental analysis and validation of bimodal water retention curves in the soil for residual sandy clay soils of the Itaqueri Formation in São Carlos - SP

Abstract

This experimental study offers parameters to validate and adjust four models of soil water retention curve (SWRC) present in the literature. The experiment was performed in the soil of the campus of the Federal University of São Carlos, State of São Paulo, using tensiometers to monitor soil matrix suction and water content at different depths. Soil samples were collected to build the SWRCs using three Whatman No. 42 filter paper calibration techniques to obtain the matrix suction by soil moisture ratio. The SWRC models were used to adjust the water content values according to the bimodal SWRC proposal. The experiment was validated in the laboratory by measuring the moisture of the samples at each depth, obtained at different dates, and then correlating them with the respective suction pressure values obtained at the time of sampling. Van Genuchten's Bourdine-restricted SWRC model and filter paper from Oliveira and Marinho obtained the best fit in representing the water dynamics in the profile in terms of the global coefficients: R², Nash-Sutcliffe, EAPM and RMSE.