Identifying opportunities for living shorelines using a multi-criteria suitability analysis

Abstract

The need to develop more sustainable solutions for coastal hazard risk reduction and to protect and restore degraded coastal habitats has led to an increased interest in living shorelines. A barrier to the wider implementation of living shorelines is a lack of guidance on where it is suitable to implement these solutions. We developed a shoreline suitability model to select areas of a representative coastline that would be either suitable for a soft (natural habitats only) or hybrid (natural habitats in combination with hard structures) approaches. We created species distribution models in MaxEnt to predict the potential distribution of 14 coastal species including four seagrasses, one mangrove, three saltmarsh, three shellfish and three dune species. These were combined in a multi-criteria analysis that also accounted for the accommodation (current space in the intertidal) and adaptation space (amount of space between the intertidal and nearest infrastructure) available to implement living shorelines at a 250 m resolution. This was done for the state of Victoria, Australia as a case study location where there is a high percentage of coastal infrastructure reaching the end of its design life. For the Victorian coastline 74% was suitable for hybrid approaches, while 65% was suitable for soft approaches and 4% of the coastline was not suitable for either approach. For the coastline already protected with hard defence structures, 67 and 69% would be suitable for at least one taxa, using a soft or hybrid approach, respectively. The percentage of coastline suitable for soft or hybrid approaches was similar in rural areas, however, suitability for hybrid was greater than soft approaches in urban and built-up areas, which could be due to a combination of habitat suitability and space available on the foreshore. This study has demonstrated how spatial multi-criteria analysis can be adapted to a complex coastal environment and inform more diverse coastal hazard mitigation actions to risk reduction and climate adaptation.