Dike Monitoring comparison between thermal camera and DTS systems for drought induced cracks on dikes.

Cracks occurring on dike surfaces due to droughts, are a big threat for the stability of flood defense infrastructure as they increase infiltration rates and reduce the resistance to mass rotational failure (slope stability). Conventional methods for crack detection heavily rely on visual inspections, drone technologies survey, or destructive techniques such as sampling and trenching. Most of them result sparse qualitative and labor-intensive assessments. Due to the increase of drought and high temperature events during summer, an effective, reliable and sustainable monitoring system for crack detection is of vital importance.

During the period May-September 2021, a semi-full-scale dike prone to cracks, was monitored using Thermal Imaging and Distributed Temperature Sensing (DTS); to collect temperature variations inside of an existing crack and at the surface of the dike. Both instruments were calibrated using temperature data from a TD-Diver datalogger and data from a nearby weather station. From the monitoring campaign it was observed that during daytime, the temperature difference between the dike surface and the crack, due to the solar radiation, becomes negligible when withdrawn from the thermal camera sensor. However, this is not the case for the DTS monitoring system. This pattern is inverted during nighttime for which the temperature differences are much more noticeable in the thermal images. Hence, we propose the thermal imaging and the DTS combined system as a good alliance to detect the spatially distributed formation and development of cracks on dikes.