The long-term weather forecast can be summed up in one word: extreme. According to the Environmental Protection Agency (EPA), years of research into the impact of rising global temperatures indicates that extreme weather conditions are becoming more common. This includes heavy rainfall events that can lead to flooding. A Federal Emergency Management Agency (FEMA) analysis of flood data from 1965-2015 confirms this, showing that the overall frequency and severity of flooding events in rivers and streams has increased in many regions of the United States. A 2022 analysis of flooding events estimates that the annualized cost of flood damage in the U.S. is $32.1 billion and is projected to rise to $40.6 billion by 2050 if current warming trends continue.
For construction and engineering firms in the regions of the U.S. expected to be most impacted by inland flooding – the Northeast, Pacific Northwest, and Midwestern Great Plains, – effective risk analysis is more important than ever when planning projects for protecting people, property, and infrastructure.
However, most risk analyses rely on historical data. How can firms plan for unprecedented risks from natural disasters driven by climate change? Lumivero’s DecisionTools Suite makes it possible to conduct effective risk-benefit analysis for construction and engineering projects, even in scenarios where past data is scarce. Here are two examples of how one Seattle-based engineering firm used DecisionTools Suite to generate solutions based on probabilistic risk analysis.
Predicting Rock Fall Scenarios with Monte Carlo Simulation
The team at Wyllie and Norrish Rock Engineers has been using @RISK for engineering and construction risk analysis regarding rock falls and other hazards for more than 25 years. In a recent project described in a Lumivero case study, a client commissioned Wyllie to design a structure that would protect a road situated under a steep, rocky slope. The team had no previous data about rock falls in the area to draw on when evaluating the potential risks the structure would need to address. With @RISK, Wyllie was able to conduct a probabilistic analysis anyway.
Primed with data about the geology of the slope and equations for determining velocity and mass, the software used Monte Carlo simulation to generate a range of all possible rock fall events a road under such a slope would face. It also predicted the statistical likelihood of each scenario and expressed each outcome as an energy impact measured in kilojoules (kJ).
Then, using PrecisionTree, Wyllie could clearly explain the potential risks and payoffs of different solutions to the client through visualizations using decision tree modeling and recommend the best path forward. This helped inform the client’s decision to commission a protective fence above the road with the capacity to absorb 1,250 kJ of energy – enough to contain 90% of rock fall events predicted by the @RISK analysis.
Decision Tree Modeling for Debris Flow Mitigation Strategies
A case study of a separate project describes how Wyllie analyzed potential hazard mitigation solutions for a residential development located within the path of a potential debris flow source. A debris flow is a fast-moving landslide that occurs when heavy rain destabilizes soil on a hill or mountain, which then breaks loose and sweeps down into surrounding terrain. Debris flows can travel at speeds of 35 miles per hour and, according to the U.S. Geological Survey, “carry large items such as boulders, trees, and cars.”
Debris flows can cause catastrophic damage. A 2022 paper by a team of scientists from Malaysia, Indonesia, and Saudi Arabia reported that landslides, including debris flows, were responsible for at least 77,800 global fatalities from 1950-2011, and that the incidence of these events are expected to rise as climate change makes extreme rainfall events more common. Just last year, at least 1,700 people in Pakistan lost their lives in debris flows following extreme rainfall in the region, and several million people were displaced by the destruction.
In the case of the residential area below the debris-flow hazard, Wyllie’s construction risk analysis determined that there were three options available:
- Do nothing
- Construct a containment dam
- Relocate the homes
Information from a study of the site’s geographical features and geology generated a 60% probability that there would be a debris-flow event within a certain number of years. That information, combined with probabilistic analysis, helped determine the probability of each outcome, the extent of damage, and the estimated cost.
Using PrecisionTree, Wyllie was able to provide the client with probabilistic modeling that clearly visualized the risk-benefit analysis of their situation, guiding an informed decision for mitigation of the debris-flow hazard – in this case, construction of a containment dam.
Robust Risk-Benefit Analysis Solutions – Even in a Changing Environment
While there is no way to predict every effect that global warming could have on our built environment, DecisionTools Suite can help engineering and construction professionals make informed decisions in the face of unprecedented risks. With risk analysis and probabilistic modeling, it’s possible to develop plans that prioritize safety, even with the uncertainty of the environmental future.
Learn more about how DecisionTools Suite can help your engineering or construction firm plan for environmental risks by requesting a free trial today. For a quick start, download the free Decision Trees in Rock Engineering example model, created in partnership with Wyllie and Norrish Rock Engineers.