Second-Pass Assessment of Potential Exposure to Shoreline Change in New South Wales, Australia, Using a Sediment Compartments Framework

Abstract

Abstract:The impacts of coastal erosion are expected to increase through the present century, and beyond, as accelerating global mean sea-level rise begins to enhance or dominate local shoreline dynamics. In many cases, beach (and shoreline) response to sea-level rise will not be limited to passive inundation, but may be amplified or moderated by sediment redistribution between the beach and the broader coastal sedimentary system. We describe a simple and scalable approach for estimating the potential for beach erosion and shoreline change on wave-dominated sandy beaches, using a coastal sediment compartments framework to parameterise the geomorphology and connectivity of sediment-sharing coastal systems. We apply the approach at regional and local scales in order to demonstrate the sensitivity of forecasts to the available data. The regional-scale application estimates potential present and future asset exposure to coastal erosion in New South Wales, Australia. The assessment suggests that shoreline recession due to sea-level rise could drive a steep increase in the number and distribution of asset exposure in the present century. The local-scale example demonstrates the potential sensitivity of erosion impacts to the distinctive coastal geomorphology of individual compartments. Our findings highlight that the benefits of applying a coastal sediment compartments framework increase with the coverage and detail of geomorphic data that is available to parameterise sediment-sharing systems and sediment budget principles. Such data is crucial to reducing uncertainty in forecasts by understanding the potential response of key sediment sources and sinks (e.g., the shoreface, estuaries) to sea-level rise in different settings.

A Regional Scale Approach to Assessing Current and Potential Future Exposure to Tidal Inundation in Different Types of Estuaries

“…Comparatively, our results show the potential future growth of exposure to inundation within estuaries to be a far greater problem in NSW than that of exposure to open coast erosion, which while nevertheless significant 52 , is an order of magnitude less than the results presented here. Overall this exposure assessment finds esturine tidal inundation to be a major coastal management issue, highlighting the need for coastal and floodplain management and planning to manage risk to current development and to avoid the unnecessary growth of risk into the future.…”

“…The geocoded urban and rural address system (GURAS) 66 was used to identify properties that were predicted to be exposed to inundation under each scenario using a similar approach to that adopted in the recent 2 nd pass erosion assessment 52 . The GURAS database stores address point data within cadastral lots.…”

Wave and Tidal Controls on Embayment Circulation and Headland Bypassing for an Exposed, Macrotidal Site

“…A key component in assessing the dynamic behaviour of a coastal cell [1,2] is knowledge of the sediment budget [3][4][5], including sediment fluxes in the cross-shore and alongshore. Cross-shore transport includes sediment movement to and from dunes (e.g., [6]), through the intertidal to sub-tidal beach (e.g., [7]) and out to and beyond the depth of closure (e.g., [8]).…”

Maximising the potential for citizen science in New South Wales

“…Beach erosion and shoreline recession caused by large storms and the gradual and ongoing redistribution of coastal sediments may result in damage to or total loss of coastal properties, infrastructure, recreational amenity, and natural habitats (Harley et al 2017;Kinsela et al 2017). Projected sea-level rise under future climate scenarios is expected to increase the impacts of storm-related beach erosion events and enhance shoreline recession along unstable coasts (Fitzgerald et al 2008).…”