Kempsey Coastal Processes and Hazards Definition Study
This report, the Kempsey Coastal Processes and Hazards Definition Study, describes the coastal processes and interactions operating on the Kempsey Local Government Area (LGA) coastline (the Kempsey coastline) and the extent of the coastal hazards arising from these processes. This report documents a summary of coastal processes, the methodology used to assess the coastal hazards, approach to hazards definition mapping, and a beach by beach summary of analyses and outcomes (focussing on the coastal villages of Kempsey).
The report was prepared in accordance with the former Coastline Management Manual (CMM) (NSW Government, 1990) and the new Guidelines for Preparing Coastal Zone Management Plans (DECCW, 2010). The report documents the coastline structure in terms of regional geology and geomorphology and coastal processes in terms of wave climate, water levels, wind processes, and projected climate change. The interactions between all of these factors governs waterborne longshore and cross shore sediment transport and windborne transport to shape the coastline evident today.
The report also outlines the methodology used to assess coastal hazards relevant to Kempsey’s coastline. This includes our approach to beach erosion incorporating wave climate variability and the use of the “world’s best practice” Shoreline Evolution Model to assess shoreline recession due to sea level rise and shoreline structures (e.g. headlands, river breakwaters, reefs).
In accordance with the NSW Government’s Guidelines for Preparing Coastal Zone Management Plans, a risk based approach using the Australian Standard Risk Management Principles and Guidelines (AS/NZS ISO 31000:2009) has been adopted for defining hazards for this study. In order to transparently account for the uncertainty in hazards estimates, the likelihood of the beach erosion and recession and inundation hazards was defined. Following the Australian Standard Risk Management Principles and Guidelines (AS/NZS ISO 31000:2009), a likelihood scale of ‘almost certain’, ‘likely’, ‘possible’, ‘unlikely’ and ‘rare’ was adopted (although only ‘almost certain’, ‘unlikely’ as a best estimate and ‘rare’ as a worst case have been mapped).
As given in ISO 31000:2009, the level of risk is the combination of the ‘likelihood’ and ‘consequence’. The Kempsey Coastal Processes and Hazards Definition study provides the essential information regarding coastal hazards and their current and future likelihood, for use in land use planning and preparation of a Coastal Zone Management Plan. Within the risk assessment framework, the definition of the ‘consequences’ of coastal hazards would be undertaken during the Coastal Zone Management Plan phase for the Kempsey coast. The outcomes of the risk approach may be used to guide land use planning as appropriate to the level of risk from coastal hazards in each beach compartment.