Optimal strategies for assigning prior boundary settings in Hydraulic Tomography analysis

•An iterative algorithm is developed to estimate optimal prior boundary head values.•Boundary size matters less for Hydrologic Tomography outcomes, regardless of data adequacy, while boundary condition type significantly impacts inversion.•Increasing boundary size can mitigate errors from incorrect boundary type assumptions. Hydraulic Tomography (HT) is a high-resolution method for identifying aquifer hydraulic property heterogeneity. Despite decades of development leading to a relative maturation of HT, the influence of prior boundary information on HT estimations warrants further investigation. In this study, HT methods were applied to a synthetic heterogeneous aquifer to examine the impact of prior boundary types, sizes, and head values on parameter estimations. Results indicate that while boundary size has limited impact on HT outcomes regardless of data adequacy, the boundary condition type is a significant factor in HT inversion. Increasing boundary size can mitigate errors from incorrect boundary type assumptions. The SimSLE-HCA iterative algorithm effectively estimates optimal boundary head values given sufficient HT survey data. For practical application, in cases where the boundary size is unknown, a moderate expansion of the simulation area is recommended. In situations where the boundary type is uncertain, designating it as a constant head boundary proves practical.