Determinação da condutividade hidráulica pelo problema inverso do software Hydrus-1D

Abstract

Knowledge of soil hydraulic conductivity is essential for any study that involves the movement of water in the soil. Their determination can be made by several methods in the field or laboratory, and its high variability among replicates is often cited as an experimental problem. The determination of physical-hydric soil by direct methods in the laboratory and obtain these functions in the field, are time consuming and costly and involve considerable uncertainty. An alternative to the direct determination of these properties is to employ the method of parameter estimation using the reverse process (inverse method). This study aimed to determine an alternative to the saturated hydraulic conductivity Ks by solving an inverse problem for the model Hydrus-1D, from cumulative infiltration data collected in the field through an infiltration test with double ring infiltrometer and the use of a moisture probe FDR. To evaluate the effect of variation in initial conditions of soil and in the objective function values of Ks estimated by inverse method, as well as determine the unsaturated hydraulic conductivity of soil and evaluate the performance of the software. It was found that there is great variability in the values of Ks estimates. The inverse problem proposed method to determine unsaturated hydraulic conductivity for a wide range of values of soil moisture and module of the matric potential as appropriate for the soils. The inverse problem is adequately defined for the estimates of Ks in the 0-20 and 20-60 cm but did not allow a reliable estimate for the layer of 60-100cm.