RISKCOAST characterize a potential threat to a critical infrastructure to the coast of Granada (Spain)

Characterising and monitoring an unstable slope is crucial when it takes place in a reservoir or the coast.

In these cases, the landslides usually lead to risky situations that may result in human, material, and/or economic losses (see examples in Schuster 2006).

Recently, Reyes-Carmona et al. (2020) identified a large landslide in the western slope of the Rules Reservoir (Southern Spain) that may represent a threat for this infrastructure that is critical to the coast of Granada province (i.e. Costa Tropical). This study triggered a new investigation under the RISKCOAST project to characterize this landslide in the shortest possible time. Thus, a retrospective analysis was applied to quantify the displacement rate of the landslide in the last years and to define in more detail its geology and kinematics. A multi-technique approach was applied integrating DInSAR, Georadar (GPR) and Drone photogrammetry (UAV-DP). This approach was very useful to obtain results in a short period of time and to check details not considered in the previous study.

Grenade landslide Rules reservoir
Unstable slope analyzed by the team of the RISKCOAST project.

$Grenade open fracture Rules reservoir$
Open fracture (in the foreground) detected in the unstable slope.

The results obtained show that the landslide has had a constant displacement for 22 years at 2 cm/yr on average. Furthermore, the InSAR results pointed out something that the previous InSAR analysis did not show. Although the movement is constant for the entire landslide mass, the toe of the landslide is slightly influenced by the water oscillation in the reservoir. This is an important point that arises from the InSAR data because this demonstrates that Rules dam operations can affect the slope and provoke the acceleration of the detected movement.

Infrastructure managers of the regional government (Junta de Andalucía) were informed about the results of the study and they are taking matters into their own hands to monitor the unstable slope and take decisions regarding the potential risk.

RISKCOAST project demonstrates with this case the importance of applying up-to-date techniques in geological hazard studies in order to improve hazard assessments and risk management.

The results of the investigation have just been published in the journal Landslides. The preprints of the paper are freely available at: Rapid characterisation of the extremely large landslide threatening the Rules Reservoir (Southern Spain)

If you want to get more information about this case please contact c.reyes@igme.es or jpgalve@ugr.es.