Estimating Permeability Using the Parameter Estimation Method in a High-permeability Area of the Kurobe River Alluvial Fan, Japan

The parameter estimation (PEST) method was used to estimate the spatial distribution of permeability coefficients in a high-permeability area of the Kurobe River alluvial fan in Toyama Prefecture, Japan. We considered spatial resolution, estimated period, soil structure, recharge source, and boundary conditions in the model. Numerical experiments produced estimated permeability coefficients that were consistent with the observed data and those of previous studies under all conditions. However, the estimated groundwater levels were lower than those of previous studies. Spatial resolution and the number of foundation layers did not have a large effect on estimates of the vertical permeability coefficient (kz). However, recharge source and boundary conditions were important for estimating permeability coefficients. Finally, the estimates of specific storage (Ss) and specific yield (Sy) were similar to the observed data under all conditions.