A growing number of local governments recognize that it is as important to understand, measure, manage and account for natural assets as engineered ones. Doing so can enable local governments to provide core services such as stormwater management, water filtration and protection from flooding and erosion, as well as additional services such as those related to recreation, health and culture. The term municipal natural assets refers to the stock of natural resources or ecosystems that a municipality, regional district or other form of local government could rely on or manage for the sustainable provision of one or more local government services. A newly developed tool called the Coastal Toolbox (CT) is a first attempt to extend the natural assets methodology to coastal issues. As a leader in natural asset management, the Town of Gibsons recognizes the importance of understanding, measuring, managing and accounting for coastal natural assets. These assets have the potential to provide significant economic benefits by mitigating floods and erosion, reducing long-term maintenance costs compared to hard/grey alternatives and providing co-benefits such as habitat conservation or improvements to local recreation areas. The project team evaluated the performance of four selected natural asset options with an assumed sea level rise of 0.24 metres, based on current RCP 8.5 mid-point scenario for Gibsons (including tidal levels, and using different design storm scenarios). The analysis is based on RCP 8.5 for Gibsons Harbour from the Canadian Extreme Water Level Analysis Tool (EWLAT). The 2070 sea level rise horizon was selected because 50 years (2020-2070) is a typical lifespan for a coastal infrastructure project and it is also a strategic mid-point for the modelling, which covers a 100-year time horizon.
In 2020-21, the Municipal Natural Assets Initiative (MNAI) piloted the Coastal Resilience project in the Town of Gibsons, B.C. to address the impacts of climate change on aging infrastructure being facing by many coastal communities across Canada. The structures originally constructed to protect communities from storm surges are aging and unable to protect against bigger and more frequent storms caused by climate change. The Town of Gibsons is situated along the perimeter of the Salish Sea at the entrance to Howe Sound or Átl’ka7tsem. As of the 2016 federal census, the town was home to 4,605 residents. Because of its coastal vulnerability, the Town of Gibsons is actively pursuing climate adaptation planning to help mitigate future damages from forecasted sea level rise and increased storm severity and frequency. The project developed and tested a Coastal Toolbox (CT) model to determine how enhancing coastal natural assets like subtidal eelgrass, coastal vegetation or beach sediments could reduce flood and erosion impacts, especially if used alongside conventional grey infrastructure. The project team made comparisons using avoided damage costs to flooded structures and a non-monetary erosion index score. The latter compares the hypothetical beach retreat from erosion given beach elevation profiles, and a wave attenuation estimate that evaluates how much subtidal features like eelgrass will mitigate waves. Preparation of this project was carried out with financial support from Natural Resources Canada’s Climate Change Adaptation Program, the Sitka Foundation, the McLean Foundation and the Bullitt Foundation.