Coupled Urban Change and Natural Hazard Consequence Model for Community Resilience Planning

This paper presents a new coupled urban change and hazard consequence model that considers population growth, a changing built environment, natural hazard mitigation planning, and future acute hazards. Urban change is simulated as an agent-based land market with six agent types and six land use types. Agents compete for parcels with successful bids leading to changes in both urban land use-affecting where agents are located-and structural properties of buildings-affecting the building's ability to resist damage to natural hazards. IN-CORE, an open-source community resilience model, is used to compute damages to the built environment. The coupled model operates under constraints imposed by planning policies defined at the start of a simulation. The model is applied to Seaside, Oregon, a coastal community in the North American Pacific Northwest subject to seismic-tsunami hazards emanating from the Cascadia Subduction Zone. Ten planning scenarios are considered including caps on the number of vacation homes, relocating community assets, limiting new development, and mandatory seismic retrofits. By applying this coupled model to the testbed community, we show that: (a) placing a cap on the number of vacation homes results in more visitors in damaged buildings, (b) that mandatory seismic retrofits do not reduce the number of people in damaged buildings when considering population growth, (c) polices diverge beyond year 10 in the model, indicating that many policies take time to realize their implications, and (d) the most effective policies were those that incorporated elements of both urban planning and enforced building codes. Plain Language Summary Natural hazards negatively impact communities resulting in significant infrastructure damages. Natural hazard mitigation planning attempts to reduce these damages and modeling can be used to measure how effective different mitigation plans can be. A new modeling framework is presented that accounts for population growth, a changing built environment, natural hazard mitigation planning, and future hazards. The model is applied to a testbed community with a large tourist population that is exposed to earthquake and tsunami hazards. Using this model, we consider different combinations of policies such as limiting the number of vacation homes in the community, relocating community assets, limiting new development, and enforcing building codes. Interestingly, we show that while placing a cap on the number of vacation homes does free up housing for full time residents, this also results in more visitors in damaged buildings. It is also shown how even with building codes in place, population growth contributes to an increased number of people in damaged buildings. Lastly, we show how the most effective policies incorporate elements of both urban planning and building codes.

Automated summary

This paper presents a new coupled urban change and hazard consequence model that considers population growth, a changing built environment, natural hazard mitigation planning, and future acute hazards. The model is applied to Seaside, Oregon, and shows that the most effective policies are those that incorporate elements of both urban planning and enforced building codes.