Threat and Impact Modeling

Fallen tree on snowy day downing a power line.

Sandia’s threat modeling work focuses on characterizing the wide-ranging impacts from natural hazards on our infrastructure sectors. Threats serve as the key input to resilience analysis, and accurate assessment of system performance depends on a knowledge of what is likely to go wrong when a disruption occurs. The threats are diverse – think hurricanes, wildfires, earthquakes, cold waves, or flooding – and the impacts are span across assets, space, and time. In many cases the threats themselves are well understood, but there is a need to better assess the impacts to infrastructure assets. By improving our understanding of both the expected disruptions from natural hazards and the likelihood of specific hazard occurrence, we provide input to foster better decisions for infrastructure planning and operations. 

Our work seeks to characterize and predict both direct and indirect impacts from specific threat types. We employ a mixture of physics-based failure models (such as established fragility curves), statistical impact models that are built using historical event data, and heuristics driven by knowledge of past events.

Given the prevalence of imperfect or missing data in this space, uncertainty quantification is a key aspect of any impact assessment. We often work to create scenarios that represent a likely range of potential impacts. This allows us to identify sensitivities or critical assets in the system to guide resilience investments and proactive planning.

Impact Assessment

Much of our work is focused on impacts to the electric grid, and we also aim to capture dependencies (and interdependencies) across other infrastructure sectors to ensure that we can provide a full view of what might go wrong. Only then can we start to determine the optimal set of decisions to improve resilience. Direct impacts from natural hazards include things like:

  • Damage to a generator from an earthquake
  • Downed power lines from hurricane-force winds
  • Icing on wind turbines, forcing them to shut down
  • Grid disconnections due to wildfire damage
  • Frozen natural gas wellheads during a cold wave event

Indirect impacts are often just as important and can be the key drivers of complications in preparation and recovery. These include things like:

  • Reductions in solar PV production due to wildfire smoke in the atmosphere
  • Forced generator outages due to fuel supply disruptions
  • Increased electricity demand during a heat wave event
  • Reduced thermal generator efficiencies due to warmer water used for cooling
  • Prolonged outages due to required repairs and recovery complications

By combining direct and indirect impacts, we can start to build multisector impact scenarios that provide a full picture, across space and time, of the factors at play to determine a system’s level of function and the consequences to customers from specific hazard events. Ideally, we can use these scenarios to analyze and improve resilience across the threat space.

Climate Change and Natural Hazards

Climate change is driving changes in the frequency and intensity of natural hazards and extreme weather events. Infrastructure assets are typically designed to function for decades, which means that the operational environment at the end of their lifespan may look very different than it does today. Thus, planning models need to explicitly account for climate change and the potential impacts on individual infrastructure assets and system demands. We are working to assess threat impacts both for today and as they evolve over time. Some examples of climate-induced threat considerations include:

  • Stronger hurricanes with greater precipitation potential
  • Changing precipitation patterns resulting in increased flood risk
  • Worsening drought conditions that may reduce hydropower supply
  • Increased frequency of heat waves that drive peak electricity demands
  • Increased frequency of cold waves due to a weakened jet stream
  • Heightened wildfire risk due to drought and high temperatures
  • Sea level rise putting assets at risk from storm surge

The hazard space is vast, and detailed characterization of all threats and all possible impacts is an active and ongoing area of research. Climate change adds a sizeable amount of uncertainty to the planning space, and we aim to create tools and data products that support decision-makers faced with these uncertainties.

Andrea Staid