Characterising and monitoring an unstable slope is crucial when it takes place in a reservoir, where 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 critical infrastructure. This study triggered a new investigation to characterize this landslide in the shortest possible time. Thus, it was applied a retrospective analysis to quantify the displacement rate of the landslide in the last years and to define in more detail its kinematics. One of the techniques applied was a multi-temporal DInSAR analysis applied through the Parallel Small Baseline Subset (P-SBAS) processing service available at the European Space Agency’s Geohazards Exploitation Platform (GEP). This service was very useful to obtain results in a short period of time and to check details not considered in the previous study.
The results obtained by GEP show that the landslide has had a continuos displacement from 2016 to 2020 (3.5 years) at 2 cm/yr in average. This velocity was validated through another technique that revealed that this rate was mostly constant for 22 years. Furthermore, the GEP results pointed out something that the previous InSAR analysis did not showed. Although the movement is constant for the entire landslide mass, the toe of the landslide is slightly influenced by the water oscilation in the reservoir. This is an important point arise from the GEP data because this demonstrate 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.
This case study is another example where GEP may have a significant impact on hazard analysis and risk management speeding up the data collection and decision making.
Unstable slope analyzed with GEP