ESTIMATING SOIL WATER INFILTRATION BASED ON PEDOFUNCTIONS / ESTIMATIVA DA INFILTRAÇÃO DE ÁGUA NO SOLO A PARTIR DE PEDOFUNÇÕES

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Knowledge on soil water infiltration is essential for the solution of problems concerning irrigation and drainage areas and those related to water and soil conservation research. In that regard, the aim of this paper was to model water infiltration rate and hydraulic conductivity in saturated soil by means of pedotransfer functions for soils of various physical characteristics in 16 sites in Rio Grande do Sul and 04 sites in Uruguay. For each site, the following variables were determined: water infiltration rate, density (soil and particle), soil porosity (macro, micro and total), texture (clay, silt and sand), initial soil moisture content, saturation and water content at 1, 6, 10, 100, 500, 1500 KPa, and hydraulic conductivity (which was measured in seven sites only). Experimental water infiltration rate was obtained by use of the Double-ring infiltrometer and data were adjusted with Kostiakovs and Hortons model. Artificial rainfalls were applied by using a simulator with stationary and oscillating nozzles. Six plots measuring 0,5 m2 were delimited by galvanized steel boards inserted into the soil. Each board was equipped with a gutter at the lower part to collect runoff water (measured at 5-minute intervals). Smiths mathematical model as modified by Cabeda was used to describe infiltration rate. Experimental hydraulic conductivity in saturated soil was carried out by using Guelphs parameter. Kostiakov1s, Hortons and Smiths parameters were adjusted by means of multivariate equations. In comparison to Kostiakovs, Hortons model resulted in overestimation of soil water capacity. For Argissolo 01 and 02 and Chernossolo, cross-comparison between Kostiakov and Hortons model and Smiths model revealed overestimation of water infiltration rate by use of Kostiakov and Hortons model. While for Latossolo 12, Neossolo, and Vertissolo 01, water infiltration values were underestimated. In determining multivariate equations for the estimation of Kostiakov and Hortons models parameters, physical-hydraulic variables adopted were density (soil and particle), soil porosity (macro, micro and total), texture (clay, silt and sand), initial soil moisture content and saturation, and water content at 1, 6, 10, 100, 500, 1500 KPa. Such equations performed suitably for all the soils investigated. The pedofunction originated from the correlation between water infiltration rate obtained by means of Kostiakov and Hortons pedofunctions and water infiltration rate obtained by means of Smiths model can adequately predict water infiltration rate as estimated by Smiths model. Obtaining pedofunction equations by use of multivariate equations for estimating hydraulic conductivity in saturated soil solo by Guelphs model is suitable for estimating the model parameters.

ASSUNTO(S)

infiltração de água pedofunction condutividade hidráulica hydraulic conductivity pedofunção ciencia do solo water infiltration

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