Delineate the unknown aquifer geometry and boundary condition using hydraulic tomography
Journal
Journal of Hydrology
Journal Volume
653
Start Page
132754
ISSN
0022-1694
Date Issued
2025-06
Author(s)
DOI
10.1016/j.jhydrol.2025.132754
Abstract
The geometric shape and boundary conditions of an aquifer are vital properties in many aspects of studies in water resources and hydrogeology. An accurate characterization of these hydraulic properties can help stakeholders manage water resources effectively and mitigate the negative impact of overexploited water resources on the environment. However, due to the complex subsurface hydrogeological characteristics and limited observations, it is challenging to effectively characterize the aquifer's geometric shape and boundary conditions. This study investigates the effectiveness of hydraulic tomography to identify unknown aquifer geometry and boundary conditions using a sandbox experiment. The results show that when the true no flux boundary is incorrectly assigned as a constant head, the low hydraulic conductivity (K) and high specific storage (Ss) zones manifest along the boundaries. The low K anomaly acts as an impermeable barrier, while the high Ss anomaly behaves as a water tank to prevent water flowing into the sandbox. Conversely, it is challenging to use the anomalous K and Ss zones to identify the constant head boundary when it is incorrectly assigned as a no flux. The estimated K values remain similar to those with the correct boundary while both anomalously high and low Ss values manifest in the vicinity of incorrectly assigned boundary. Therefore, to prevent misinterpretation, a constant head boundary should be used when the boundary condition is unknown. In addition, the transient state measurements provide a more reliable assessment of boundary conditions than the steady state measurements. The partially redundant temporal measurements offset the influences of measurement noise. Finally, the hydraulic tomography is effective in identifying no flux boundary conditions when both aquifer geometry and boundary type are unknown. The low K and Ss anomalies emerge near the locations of true no flux boundaries. However, identifying constant head boundary remains a challenge, as the K and Ss anomalies did not clearly correspond to the actual locations of constant head boundaries. These analyses aid in developing strategies to specify the unknown aquifer geometry and boundary conditions, enabling scenario analysis of regional water resources management.
Subjects
Groundwater
Hydraulic Tomography
Inversion
SDGs
Publisher
Elsevier BV
Description
Article number: 132754
Type
journal article