An integrated method for the determination of set-back lines for coastal erosion hazards on sandy shores

Abstract Coastal hazards affect the majority of sandy shores worldwide, and are responsible for damage to, and destruction of, property and infrastructure. The research reported here presents an integrated method for defining set-back lines associated with coastal hazards on sandy shores for a 50-year period of interest. The method is based on a worst-case scenario approach, the shoreline evolutionary trend being the basis for the initial set-back line determination. Set-back lines are afterwards adjusted by incorporating changes associated with the acceleration of sea-level rise and the evaluation of the consequences (instantaneous shoreline retreat and overwash) of an extreme storm. The method considers different approaches depending on the shoreline behaviour (erosion, dynamic stability or accretion). The set-back lines as determined are plotted over rectified aerial photographs, allowing for a straight-forward interpretation of results. The method was applied to a test case within a barrier island system (Ancao Peninsula, Ria Formosa, Algarve, Portugal). This study area was chosen because it exhibits the three different types of shoreline evolution. The method easily shows the differences in erosion-related coastal hazards along the study area, being an important tool for coastal management. However, the method should be able to be refined at every 5–10 years, for a new 50-year period, by integrating new formulations based on advances in coastal science, and by including updated information and data about the areas to which the method is applied.

[1]  Jinrong Hu,et al.  Coastal Environments , 2020, Coastal and Marine Environments.

[2]  E. N. Buckley,et al.  Technological options for adaptation to climate change in coastal zones , 2001 .

[3]  Ana Vila-Concejo,et al.  The first two years of an inlet: sedimentary dynamics , 2003 .

[4]  J. Taussik,et al.  Partnership in coastal zone management. , 1996 .

[5]  Gerhard Masselink,et al.  Morphodynamics of meso- and macrotidal beaches: examples from central Queensland, Australia , 1995 .

[6]  O. Pilkey,et al.  Society and Sea Level Rise , 2004, Science.

[7]  J. S. Schoonees,et al.  Evaluation of 10 cross-shore sediment transport/morphological models , 1995 .

[8]  Charles Day,et al.  Sea-Level Rise Exacerbates Coastal Erosion , 2004 .

[9]  J. Houghton,et al.  Climate change 2001 : the scientific basis , 2001 .

[10]  Ó. Ferreira.  Morfodinâmica de praias expostas: aplicação ao sector costeiro Aveiro-Cabo Mondego , 1998 .

[11]  M. Pajak,et al.  Coastal Flood Hazards and the National Flood Insurance Program , 1999 .

[12]  John B. Herbich,et al.  Handbook of Coastal Engineering , 2000 .

[13]  W. J. Neal,et al.  Utilization of geoindicators for rapid assessment of coastal-hazard risk and mitigation , 1999 .

[14]  W. J. Neal,et al.  Coastal geologic hazards , 1988 .

[15]  Robert J. Nicholls,et al.  Climate change and coastal management on Europe's coast , 2005 .

[16]  L. Miller,et al.  Mass and volume contributions to twentieth-century global sea level rise , 2004, Nature.

[17]  P. Bruun.  Sea-Level Rise as a Cause of Shore Erosion , 1962 .

[18]  Shunqi Pan,et al.  The predictability of cross-shore bed evolution of sandy beaches at the time scale of storms and seasons using process-based Profile models , 2003 .

[19]  Robert G. Dean,et al.  Convolution Method for Time-Dependent Beach-Profile Response , 1993 .

[20]  Jurjen A. Battjes,et al.  RUN-UP DISTRIBUTIONS OF WAVES BREAKING ON SLOPES , 1971 .

[21]  M. Crowell,et al.  Shoreline-position forecasting: Impact of storms, rate-calculation methodologies, and temporal scales , 2001 .