Bretherton, E.; Horspool, N.A.; Syed, Y.I.; Miller, V.L.; Paulik, R. 2023 Riskscape™ case studies : informing land-use planning through natural hazard and climate-change risk modelling. GNS Science report 2023/18. doi: 10.21420/DDFC-KA58
Abstract
Aotearoa New Zealand faces substantial challenges to respond to natural hazard risk and climate change. This is compounded by the need to provide residential zoned land for urban housing needs, commercial and industrial land for economic development and also maintain rural land for primary production. Scalable processes and frameworks are needed to support effective and efficient decision-making that is both robust and replicable. Therefore, tools that can be used to face these challenges and avoid maladaptation are needed. This report demonstrates ways in which RiskScape™, an open-source spatial data processing application used for multi-hazard risk analysis, can be used to produce evidence-based risk assessments incorporating different land-use planning directions, hazard mitigation and adaption strategies and risk acceptance/tolerance thresholds.Four challenges encountered by planning practitioners have been explored: Greenfield development with multiple hazards. Policy interventions (protect, avoid, reduce and accept) within an urban flood plain. Climate-change interventions and scenarios, land-use intensification settings and adaptation options in a coastal setting. A component of a Dynamic Adaptive Policy Pathway (DAPP) approach for a coastal settlement. The focus of this study was on the Auckland region and included four case studies to highlight the capability of RiskScape™. While content for these cases has been developed in collaboration with Auckland Council to provide applied and relevant examples, the outputs do not represent or consist of direction or recommendation for Auckland Council to implement, nor do they represent possible changes to policy settings, such as level of tolerable risk being considered by Auckland Council. These cases were selected as they are replicable and relevant across Aotearoa New Zealand and demonstrate the ways in which RiskScape™ can be used to support consultation, cost-benefit analysis, adaption options and, ultimately, decision-making.The results from these cases include: identification of hazards (none/one/multiple) in a future development area to inform further spatial planning. Flooding in an urban area with an output of a range of options showing how different adaptation options could reduce the risk by targeting specific high-risk areas, while still allowing for some development potential to be retained. In the coastal context, understanding that the impact on risk from climate change and intensification – the impact of retreat / no further intensification – could reduce the overall risk in an area to an acceptable level. Also, understanding with increased certainty when some residential dwellings can expect ongoing disruption to access due to coastal inundation, as well as the suitability of triggers in a DAPP process.
