The Potential of Radiomagnetotellurics for Detecting Dike Instabilities

With rising sea levels and frequent heavy rainfall, water retention structures such as dikes become increasingly susceptible to failure. Therefore, there is a need to monitor such structures in a time and cost-efficient manner, and sufficient resolution. Electromagnetic geophysics could potentially be used for this purpose, since instability features such as water underflow or animal paths change the electrical conductivity inside the dike. In this project, we study if the Radiomagnetotelluric method can be used to investigate dikes for instability features.  First, we perform forward and inverse simulations with a synthetic dike model to verify the feasibility of the method for the purpose of detecting dike instabilities. Next, we will define suitable frequencies and measurement setups through a synthetic survey design study. Subsequently, we will apply the newly acquired knowledge from the synthetic experiments to conduct a Radiomagnetotelluric survey on a dike in the Netherlands. Dikes are often situated in populated areas, which means that significant cultural noise must be accounted for during the data processing. Through 2D and 3D inversions we will generate resistivity models of the Radiomagnetotelluric data and compare them to a resistivity model obtained from ERT data to validate the results. The final objective is to evaluate the potential of the method for practical dike monitoring and give recommendations for its implementation.