Assessment of alluvial aquifer heterogeneity and development of stochastic hydrofacies models for the Hat Yai Basin in Southern Thailand

In previous studies, the groundwater flow models formulated for the Hat Yai Basin were conventional and deterministic because the geologic heterogeneity of the alluvial aquifer system in the basin had not yet been assessed. This paper describes an effort to develop hydrofacies models, such that the spatial variability of the aquifer system can be represented in a systematic way. Variogram parameters that characterize the alluvial aquifer heterogeneity were determined. Based on these variogram parameters, an indicator-based geostatistical approach was used to develop hydrofacies models using sequential indicator simulation. The hydrofacies models indicate three distinct aquifer units, namely Hat Yai, Khu Tao, and Kho Hong aquifers, which is in good agreement with a conceptual model, and incorporates spatial variability as observed in field data from borehole logs. The hydrofacies models can be used in groundwater modeling and simulations.