The effect of sea-level rise is particularly felt during storm surges. 30-40cm of sea-level rise from 2005 will mean that what was historically a 1 in 100-year event is very likely to happen every year. The extremes become the new average and new thresholds for extreme events will evolve through time.
We are attempting to project future coastal change that will interact with sea-level rise. Our research is likely to include examination of wave projections, erosion and progradation, estuarine change, mapping dunes and cliff tops, and understanding the impact of storm surges so we can try and map the evolution of the shoreline over the next few decades.
From this we will then develop and apply modelling frameworks to assess the impact of climate change at the coast. The models will focus on assessing the sediment budget at the coast and will project change over the long-term accounting also for the effect of sea-level rise.
Develop downscaled (5km resolution) wave climate projections at the national scale
We will couple two well established numerical models of wave dynamics (Wavewatch III and SWAN), and downscale the projections from global climate models for the whole coast of Aotearoa New Zealand. The projections of five global climate models will be used to generate wave characteristics (e.g., height, period, direction) for an historic and future (2080-2099) period, under shared socio-economic pathways 8.5 and 4.5. This unique dataset will be made freely available to users through our data visualisation tools.
Develop a hydrodynamic model on an unstructured grid to provide projections of storm surge at a national scale and for selected regional case studies
We will address the problem of establishing a reliable database of projections from storm surge by developing a novel unstructured model that will allow us to achieve unprecedented resolution (<10 km) for the coastline of Aotearoa New Zealand. The projections of five global climate models will be used to generate changes in water levels driven by storm surge for an historic and future (2080-2099) period, under socio-economic pathways 8.5 and 4.5. This unique dataset will be made freely available to users through our data visualisation tools.
Develop a high-level sediment budget for open coasts at the national scale
We will simulate coastal change out to 2050 using a large-scale sediment budget with predictions generated from this project on erosion data, local sea-level rise, wave climate, tide and storm surge. The model will account for scenarios of varying sediment input from the catchments as well as the effect of sea-level rise and varying wave climate. This modelling will provide the backbone for the regional case studies.
Develop a high-level sediment budget and landform evolution for estuaries at the national scale
We will simulate estuarine change out to 2050 using a large-scale sediment budget. The model will account for scenarios of varying sediment input from the catchments as well as the effect of sea-level rise on the evolution of tidal flats and estuarine morphodynamics.
Predict short-term (decadal-scale) shoreline evolution using data-driven models at selected regional scales
Building on previous Ministry of Business, Innovation and Employment funded projects and using the projections of sea-level rise and wave climate generated in this project, we will tackle the problem of predicting long-term shoreline change using established models (e.g., SHOREFOR, SPADS) and recently developed convolutional neural networks. The data necessary to simulate shoreline change will be acquired from available shoreline-from-satellite databases.
Develop models to examine erosion along steeper open coastlines and the sedimentary response at selected regional scales
Waves undercut coastal hillslopes over time, progressively destabilising them. However, we cannot confidently predict future land sliding nor quantify the increases in frequency and magnitude that are likely to occur under climate change. This is because we can’t yet directly attribute each landslip to the causes of the slip itself. We have selected a study site in Taranaki where coastal erosion and land sliding is occurring at among the fastest rates in Aotearoa New Zealand. This gives us the smallest possible window between driver (e.g. wave undercutting) and response (e.g. land sliding). We have devised a monitoring programme with the potential to provide synchronised high frequency measurements of landslide activity with a large suite of environmental drivers that could be responsible for these failures.
Our Team
Giovanni Coco, University of Auckland, and Karin Bryan, University of Auckland, are world-leading coastal scientists and together will lead the hydrodynamic shoreline and sediment transport modelling. Mark Dickson, University of Auckland, and Saskia de Vilder, Earth Sciences New Zealand (formerly GNS Science), bring expertise in coastal cliff erosion and landslide hazard assessment and close collaboration with the Resilience to Nature’s Challenges National Science Challenge. Tom Durrant, Oceanum Ltd, and Peter McComb, Oceanum Ltd, will develop the national wave climate model.