Regional implementation of coastal erosion hazard zones for archaeological applications

Abstract

Abstract
Coastal archaeological heritage is in danger of being lost to coastal erosion, the risk of which is amplified by accelerating sea-level rise (SLR). In Aotearoa/New Zealand, coastal archaeological heritage is closely associated with indigenous ancestral communities, but our understanding of the spatiotemporal variability in coastal erosion risk for cultural heritage is limited. Coastal erosion hazard zones have typically been implemented to manage erosion risk to modern infrastructure at regional scales. In this study, we applied a hazard zone methodology in the context of coastal archaeological heritage for a selected region of Aotearoa (Te Tai Tokerau/Northland). Historical coastal change analyses reveal that most beaches in the region have been stable or slightly accretionary over the past ∼80 years, but a reversal of this trend is likely under the projected SLR, which is expressed in the coastal erosion hazard zones. Our analyses indicate that ∼8 % (155) of coastal archaeological sites in Te Tai Tokerau/Northland may be at risk of erosion with a relatively modest 20 cm of SLR, which is expected for the region by 2040, and ∼19 % (356) of sites are threatened by 1 m of SLR. Scenarios are presented that should assist a broad range of stakeholders to assess heritage risk and provide an opportunity for coastal managers to include heritage within adaptive planning pathways.

Highlights
• Hazard zone methodology: The paper employs a hazard zone methodology, typically used for managing erosion risk to modern infrastructure, to assess and manage the risk to coastal archaeological heritage.

• Coastal archaeological heritage at risk: Coastal archaeological heritage in Aotearoa/New Zealand is under threat from coastal erosion, with accelerated risk due to rising sea levels.

• Projected sea-level rise impact: The study predicts that a relatively modest 20 cm of sea-level rise, expected by 2040, may put around 8 % (155) of coastal archaeological sites at risk, and a more significant 1 m of sea-level rise could threaten approximately 19 % (356) of sites.

• Connection to indigenous communities: The coastal archaeological heritage is closely tied to Māori, the indigenous ancestral communities of Aotearoa/New Zealand.

• Adaptive planning pathways: Scenarios are presented to assist stakeholders in assessing heritage risk, providing an opportunity for coastal managers to incorporate heritage considerations into adaptive planning pathways.