Abstract:
Precise estimation of unsaturated hydraulic
properties of porous media is indispensable in various
study areas, such as analyzing the moisture flow, the drying
process occurring from the surface, and the pollutant
migration beneath the ground surface. Although many
empirical/theoretical models describing the unsaturated
hydraulic properties have been proposed by several previ ous researchers, the best model for the different types of
soil/rock may not be identical. Thus, the model selection
process and the estimation technique of the parameters
included in the models should be developed. In the present
study, the inverse technique based on the transient evapo ration change was investigated to select the model and
estimate the model parameters. The experimental work was
based on a relatively low permeable soft rock and a rela tively high permeable sandy soil (Toyoura standard sand).
Experimental equipment was developed to precisely mea sure the evaporation rate for the high permeable sandy soii. The Genetic Algorithm (GA) was adopted in the inverse
technique as an optimization tool. In order to simplify the
problem, only the drying process from the saturated con dition was considered. It was established that the infor mation concerning the transient evaporation change could
be used for the model selection and parameter estimation.
Further, the saturation distribution could be used for the
selection of the models. The present study provides
important information for the development of the model
selection process
