Diagnosis of concentrated leakage channel embedded in dam base by means of hydraulic tomography

Concentrated leakage channels formed in dam foundations have severe impacts on the safety of hydraulic structures. Appropriate and effective measures of prevention and remediation rely on detecting the potential spatial location and direction of concentrated leakages. In this paper, a recently developed hydraulic tomography (HT) technique is introduced to detect and locate the channels. An HT process is composed of several sequential pumping tests, data collection, and hydraulic parameter inversion. Numerical experiments designed under different conditions are carried out to test the feasibility and accuracy of HT for investigating dam-concentrated leakages. Simulation results show that even with a few pumping wells, observation ports and known hydraulic conductivities (K), the preset leakage channel, which is represented by high-K zones, can be identified. By increasing the number of pumping wells and observation ports involved in the HT test, the channel becomes legible, and the heterogeneity in the estimated K field approaches that of the true K field.