What are the most effective ways to assess landslide risk for construction sites?

1 Identify the landslide triggers

Assessing landslide risk begins with identifying the potential factors that can trigger or increase the likelihood of landslides at your site. These factors can be natural or human-induced, and vary based on the location, climate, geology, and topography. Common triggers include heavy rainfall or snowmelt that can saturate the soil, earthquakes or volcanic eruptions that can shake the ground, erosion or undercutting of the slope base by rivers, streams, or waves, changes in groundwater level or pressure, deforestation or vegetation removal, excavation or filling that can alter the slope geometry and load distribution, and construction activities or traffic that can generate vibrations or surcharges on the slope. To identify these triggers, you should conduct a site investigation that includes a geological survey, a hydrological analysis, a historical review, and a field inspection. Additionally, consulting with local authorities, experts, or communities can provide relevant information and data.

2 Evaluate the slope stability

In order to assess landslide risk, it is necessary to evaluate the slope stability of your site, which is the ability of the slope to resist failure under existing or expected conditions. To do this, you can collect and test soil samples, measure the slope geometry and groundwater level, and apply a method or tool based on the complexity and accuracy required. Qualitative methods such as the landslide susceptibility map (LSM) or the landslide hazard zonation (LHZ) can be used to classify the slope according to susceptibility to landslides. Semi-quantitative methods such as the infinite slope model (ISM) or rainfall threshold model (RTM) can estimate factors of safety (FOS) or probability of failure (POF). Quantitative methods such as limit equilibrium method (LEM) or finite element method (FEM) can simulate slope behavior and failure mechanisms under various scenarios. Ultimately, these tools and methods will help you evaluate the slope stability and provide valuable insights into improving your site's landslide risk.

3 Estimate the landslide consequences

The final step to assess landslide risk is to estimate the landslide consequences, which are the potential impacts or losses that can result from a landslide event in your site. These impacts or losses can range from physical, economic, social, or environmental and can affect a variety of stakeholders such as project owners, contractors, workers, residents, or the public. Commonly seen landslide consequences include damage to structures like buildings, roads, bridges, and utilities that can compromise their functionality, safety, or value. Additionally, injury or death to people exposed to the hazard or its aftermath may occur. Disruption or delay to the construction schedule, budget, or quality can also impact project performance or reputation. People living near the landslide area may be displaced or evacuated which can cause stress and trauma. Lastly, degradation or contamination of land, water, or air resources can harm the ecosystem or human health. Estimating these consequences requires assessing the exposure, vulnerability and resilience of affected elements and applying the appropriate method or tool such as the landslide risk matrix (LRM) or the landslide risk assessment (LRA) to quantify the risk level or expected loss for each element.

4 Here’s what else to consider

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