Summary Report HAWKE’S BAY, NEW ZEALAND: GLOBAL CLIMATE CHANGE AND BARRIER-BEACH RESPONSES Paul D. Komar and Erica Harris Consulting Oceanographers 3520 NW Elmwood Drive Corvallis, Oregon 97330 USA
[email protected] Report to the Hawke’s Bay Regional Council November 2014 SUMMARY: Elevations of the Hawke’s Bay beaches and backshore properties were altered by a major earthquake in 1931, tilted in the longshore direction such that at the north end of this shore they were raised by 2 metres, while elevations dropped by about 1 metre at its south end. Along the shore that had been elevated, the morphology was altered from a low-lying spit that had experienced frequent overwash occurrences during storms, into a gravel barrier ridge where the increased stability permitted the construction of homes, forming the communities of Westshore, Bay View and Whirinaki. The shore to the immediate south of Napier, which had experienced only a small degree of uplift, has remained susceptible to wave overtopping during major storms, while properties at the far south where subsidence occurred have experienced significant erosion impacts over the decades (the communities of South Haumoana, Te Awanga and Clifton). With projections of future accelerated rates of rising sea levels and increased storm intensities due to Earth’s changing climate, concerns are that the tectonically elevated stretch of the developed barrier gravel ridge will experience enhanced shorefront erosion, and potentially a return of wave overtopping during major storms, while the impacts where erosion problems already exist will experience still greater losses of properties and possibly the flooding of low-lying areas well inland from the barrier ridge.