RiskScape, a joint venture between GNS Science and NIWA, is a tool for analysing potential economic and human impacts and losses from multiple natural hazards. It can be used to balance the cost of protection measures (such as flood defences, earthquake strengthening or insurance cover) against these losses.
RiskScape converts asset and hazard information into likely impacts on a locality or region - predicting, for example, building damage and replacement costs, human casualties, economic losses, business disruption, and the numbers of people injured and displaced.
New Zealand is vulnerable to a wide variety of natural hazards, from volcanoes and earthquakes to floods and tsunamis. If we are to prioritise resources to combat these hazards, we need to know which hazards have severe impacts on our communities.
Impacts are much wider than direct damage to our built environment - they include effects on people and society. Indirect losses include the disruption of economic and social activities both within and beyond the area of immediate direct physical impact.
The quantitative assessment of both direct and indirect natural hazard impacts provides the public, planners and emergency managers with a comprehensive and detailed overview of possible consequences. This enables them to assess the relative risk of different hazards and optimise mitigation measures and response strategies, saving lives, money and minimising community disruption when a disaster occurs.
NIWA, in partnership with GNS Science, has developed RiskScape - a multi-hazard impact and risk assessment tool for New Zealand.
RiskScape combines current scientific and engineering knowledge about New Zealand's natural hazards, the built environment, land uses, and the social characteristics of communities. This knowledge has been used to develop a powerful loss-modelling software tool for quantifying the potential impacts of events within different localities or regions.
One of the strengths of RiskScape is the ability to incorporate existing databases (e.g., building attributes and road networks), hazard models (e.g. tsunami inundation extent, volcanic ash fallout), and hazard-loss curves (e.g. the damage from flooding on a 1960's weatherboard house). These are then used to estimate the impact or loss when the assets are exposed to a given hazard of a given magnitude.
This provides the flexibility to use existing hazards and risk studies within RiskScape rather than having to start from the beginning each time.
Another advantage is that consequences such as damage to buildings are calculated for each individual asset and are then be aggregated to larger areas (for example, a suburb), dependent on the requirements and any confidentiality aspects of the asset databases.
The RiskScape model
The RiskScape model is based on the generic model for calculating risk from natural hazards. This can be summarised as:
Risk depends on Hazard & Exposure of Assets & Consequences
There is no risk if there is no hazard, no assets or no consequences.
Risk is present when a hazard (e.g. flooding) exposes assets (e.g. buildings) to hazardous processes (e.g. flood depth, velocity and duration). If assets are vulnerable (e.g. damage depends on earthquake intensity), this results in consequences (e.g. monetary losses).
The RiskScape tool comprises Hazard, Asset and Vulnerability modules. Each module contains information on a component of the risk calculation process:
- the Hazard Module contains data on hazard intensity (e.g. wind speed)
- the Asset Module contains data on asset types and attributes exposed to the hazard (e.g. residential building - timber, 1 story, age pre 1960)
- the Vulnerability Module contains models of the consequences or impacts resulting from the hazards interacting with the assets (e.g. % building damage from shaking intensity X).
The resulting risk for individual assets is aggregated over an area containing multiple assets, to lessen some of the uncertainties involved in modelling risk for individual assets.
The main sequence of operations for a RiskScape model run is shown on the right, from simulating the natural hazard through to calculating damages and losses for vulnerable communities and assets.
RiskScape currently covers five natural hazard types:
- flooding (river)
- volcanic ash fall
- coastal storm-tide inundation.
Enhancements in the near future will include extending the list of hazards:
- landslides (both earthquake and rainfall triggered)
- proximal volcanic hazards (pyroclastic flows and lahars)
- snow storms
- climate change effects,
RiskScape's initial goal is to become a useful tool for government, emergency management groups, utility companies and other organisations involved in managing the impacts of natural hazards. To achieve this, we have partnered with three diverse geographical areas - Westport (Buller District Council, West Coast Regional Council), Napier/Hastings (Hawke's Bay Regional Council, Hastings District Council, Napier City Council) and Christchurch (Christchurch City Council and Environment Canterbury) - to use the tool in modelling the impacts of natural hazards on their assets (people, buildings and infrastructure). From these partnerships, the RiskScape model prototype has been developed and is available for evaluation by appropriate users. The RiskScape website has more details.
RiskScape model outputs can support a number of natural hazard management activities that need a quantitative impact or risk assessment.
- comparative risk assessment
- land use planning
- civil defence emergency management planning
- emergency response exercises and plans
- recovery planning
- public education
- earthquake prone building policy formulation
- asset management
- infrastructure management
- natural hazard insurance
- local government risk and assurance.