Assessing vulnerability to sea-level rise using a coastal sensitivity index: a case study from southeast Australia

Many of the world’s coasts appear vulnerable to the impacts of climate change and sea-level rise. This paper assesses the application of a coastal sensitivity index (CSI) to the Illawarra coast, a relatively well-studied shoreline in southeast Australia. Nine variables, namely (a) rock type, (b) coastal slope (c) geomorphology (d) barrier type (e) shoreline exposure (f) shoreline change (g) relative sea-level rise (h) mean wave height and (j) mean tide range, were adopted in calculation of the CSI (the square root of the product of the ranked variables divided by the number of variables). Two new variables, shoreline exposure and barrier type, were trialled in this analysis and the extent to which these increased the discriminatory power of the index was assessed. Four iterations of the CSI were undertaken using different combinations of ranked variables for each of 105 cells in a grid template, and the index values derived were displayed based on quartiles, indicating sections of coast with very high, high, moderate and low sensitivity. Increasing the number of variables increased the discriminatory power of the index, but the broad pattern and the rank order were very similar for each of the iterations. Rocky and cliffed sections of coast are least sensitive whereas sandy beaches backed by low plains or dunes record the highest sensitivity. It is difficult to determine shoreline change on this coast, because individual storms result in substantial erosion of beaches, but there are prolonged subsequent periods of accretion and foredune rebuilding. Consequently this variable is not a good indicator of shoreline sensitivity and the index is unlikely to provide a clear basis for forecasting future recession of beaches. The results of this study provide a framework for coastal managers and planners to prioritize efforts to enhance the resilience or consider adaptation measures in the coastal zone within a study region. Sensitivity of the coast if considered in conjunction with other social factors may be an input into broader assessments of the overall vulnerability of coasts and their communities.

[1]  J. Hay,et al.  Coastal Systems and Low-Lying Areas , 2014 .

[2]  C. Sharples,et al.  Indicative Mapping of Tasmanian Coastal Vulnerability to Climate Change and Sea-Level Rise: Explanatory Report (Second Edition) , 2006 .

[3]  M. Doyle Clast shape and textural associations in peperite as a guide to hydromagmatic interactions: Upper Permian basaltic and basaltic andesite examples from Kiama, Australia , 2000 .

[4]  P. Cowell,et al.  GIS-Based Coastal Behavior Modeling and Simulation of Potential Land and Property Loss: Implications of Sea-Level Rise at Collaroy/Narrabeen Beach, Sydney (Australia) , 2004 .

[5]  J. Palutikof,et al.  Climate change 2007 : impacts, adaptation and vulnerability , 2001 .

[6]  Brian G. Jones,et al.  Stratigraphy and chronology of receding barrier-beach deposits on the northern Illawarra coast of New South Wales , 1979 .

[7]  O. V. D. Plassche,et al.  Coastal evolution -- Late Quaternary shoreline morphodynamics , 1995 .

[8]  J. Hansom Coastal evolution. Late quaternary shoreline morphodynamics , 1997 .

[9]  G. Perillo,et al.  Vulnerability to Sea-Level Rise on the Coast of the Buenos Aires Province , 2007 .

[10]  T. Wilbanks,et al.  Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change , 2007 .

[11]  B. Thom Transgressive and regressive stratigraphies of coastal sand barriers in southeast Australia , 1984 .

[12]  P. Abuodha Application and evaluation of shoreline segmentation mapping approaches to assessing response to climate change on the Illawarra Coast, South East Australia , 2009 .

[13]  N. White,et al.  Sea-level rise around the Australian coastline and the changing frequency of extreme sea-level events , 2006 .

[14]  C. Woodroffe,et al.  The Coast of Australia , 2009 .

[15]  Roshanka Ranasinghe,et al.  The Southern Oscillation Index, wave climate, and beach rotation , 2004 .

[16]  B. Sanderson,et al.  Future Directions for Wave Data Collection in New South Wales , 2005 .

[17]  William John Bamberry Stratigraphy and sedimentology of the late Permian Illawarra coal measures, Southern Sydney Basin, New South Wales , 1991 .

[18]  Colin D. Woodroffe,et al.  Australian approaches to coastal vulnerability assessment , 2008 .

[19]  K. Nageswara,et al.  Sea-level rise and coastal vulnerability: an assessment of Andhra Pradesh coast, India through remote sensing and GIS , 2008 .

[20]  J. Shaw,et al.  Sensitivity of the coasts of Canada to sea-level rise , 1998 .

[21]  E. Robert Thieler,et al.  National assessment of coastal vulnerability to sea-level rise; preliminary results for the U.S. Gulf of Mexico Coast , 2000 .

[22]  E. Robert Thieler,et al.  The Digital Shoreline Analysis System (DSAS) version 3.0, an ArcGIS extension for calculating historic shoreline cange , 2005 .

[23]  V. Gornitz Global coastal hazards from future sea level rise , 1991 .

[24]  Andrew D. Short,et al.  Handbook of beach and shoreface morphodynamics , 1999 .

[25]  E. Thieler,et al.  Coastal Vulnerability Assessment of Padre Island National Seashore (PAIS) to Sea-Level Rise , 2004 .

[26]  E. Robert Thieler,et al.  National assessment of coastal vulnerability to sea-level rise; U.S. Atlantic Coast , 1999 .

[27]  S. Cutter,et al.  Erosion Hazard Vulnerability of US Coastal Counties , 2005 .

[28]  P. Cowell,et al.  Coastal Evolution: Wave-dominated coasts , 1995 .

[29]  T. F. Lynch Stratigraphy and Chronology , 1980 .

[30]  R. Mclean,et al.  From Foreshore to Foredune: Foredune Development Over the Last 30 Years at Moruya Beach, New South Wales, Australia , 2006 .

[31]  P. Roy,et al.  Late Quaternary marine deposition in New South Wales and southern Queensland — An evolutionary model , 1981 .

[32]  P. Kanciruk,et al.  Assessment of global coastal hazards from sea level rise , 1989 .