Geohazard Assessment methodology involves a systematic approach grounded in geological and geotechnical studies conducted through successive steps: geohazards identification, risk evaluation, and mitigation solutions design. Each step is crucial for providing relevant information for accurate analyses. Specialists from various fields collaborate to ensure information is relevant throughout the whole study. Starting with geological surveys to identify hazards, the process utilizes safety analysis tools to estimate risks associated with these hazards and designs appropriate solutions with a geotechnical approach.
Field investigation vs desktop studies
In mountainous environments, systematic measurements are challenging due to wide surface areas and difficult to access cliffs. Geohazard experts are mobilized, first to characterize hazards based on their typologies and develop the appropriate methodology for conducting analyses. Data acquisition follows this methodology and three combined approaches are employed:
- Field acquisition: geologists conduct field studies to characterize the geology and geomorphology of geohazards. Field applications and database management are essential for organizing the survey and producing maps.
- Geophysics: various tools, such as Sisprobe, are useful for highlighting surface or underground limits, such as lithological unit contacts and structural discontinuities.
- Remote sensing: numerical tools combine well known technologies with AI assistance. Drones’ images and DMT/Lidar enable machine learning to automatically digitalize geohazard features.
The combination of field and desktop studies is necessary to ensure mutual quality control. Data is correlated, validated and extrapolated to cover the total study surface area.
Geohazards risk assessment
Identification of geohazards is based on observations of past events, where rocks and soils (ground) have demobilized and remobilized in naturally occurring events, revealing typical features in the landscape. Study of such features provides crucial information regarding the type, intensity and frequency of given geohazards. These parameters are required for the assessment of the risks associated with each identified geohazard.
- Geomorphological study: field surveys and DTM analyses crosscheck geological observations, especially structural measurements, with slope gradient maps to identify homogeneous zones with similar geohazards’ characteristics.
- Historical investigations: identification of historical records from human archives and compare old and recent aerial photos.
- Modeling: once parameters’ acquisition is completed, adapted software’s are used to run simulations of successive geohazards. Impacts of potential events are modelled.
Mitigating vs monitoring geohazards
Solutions to mitigating hazards depend on the risks identified, with designs proposed accordingly. The possibility of mitigating a geohazard is not systematic and can, for example, be influenced by factors such as the volumes of earth mobilized by the event. The possibility to predict, with precision, an event is not always possible, depending on the event’s sudden or progressive nature. Control of geohazards follows two main approaches:
- Elimination of the risk that could potentially impact a specific target involves:
- Removing the hazard by scouring.
- Retaining it with active systems such as cable nets, anchors, shotcrete, etc.
- Deviating or stopping it before impact installing passive systems such as barriers, shelter, etc.
Dimensioning of these systems involves geotechnical analyses based on slopes, density, kinetics, volumes. High-quality analyses based on accurate parameters guarantee appropriate and sustainable design.
- Predicting the risk and alerting about the imminent occurrence of an event involves:
- Monitoring movement utilizing advanced instrumentation, such as connected sensors or satellite interferometry.
- Detecting sudden events where it is only possible to communicate an alert to evacuate the impacted area might be possible.
- Data management, including transfer and treatment, relies on modern communication technologies to develop appropriate and effective emergency response plans.
Ultimately, geohazard assessment is a multifaceted methodology that integrates geological and geotechnical expertise across several systematic and comprehensive approaches. Along with collaboration among specialists and the use of cutting-edge technologies, robust, sustainable solutions are unlocked that enhance safety and resilience against geohazard threats in mountainous regions.
