The Council has commissioned several coastal hazard assessments over a period of years as new information becomes available to ensure that we have a strong understanding of coastal processes and hazards.

2017 Coastal Hazard Assessment

The 2017 Coastal Hazard Assessment [PDF, 8.1 MB] for Christchurch and Banks Peninsula provides information on coastal flooding and erosion for the main inhabited coastal parts of the Christchurch District. Four climate change and sea-level rise scenarios have been considered out to 2065 and 2120.

The report is the result of a thorough and independent peer review of the 2015 Coastal Hazards Assessment. A peer review panel made recommendations for changes to the 2015 Assessment and further investigations. These recommendations have been addressed in the 2017 report.

The report has been independently peer reviewed to ensure it met the panel’s recommendations.

We've put together a summary of the report [PDF, 1.9 MB] to help you understand the key terms, the methodologies, and an overview of the mapping information across our different coastal environments.

Please note a correction to Figure H-38 in the report:  The line type (seawall) shown at the Bridge Street bridge is incorrect. The line shown at the bridge represents the practical ‘upstream’ extent of the coastal hazard inundation modelling where inundation from the sea is likely to dominate flooding derived from catchment flooding. Further upstream flooding is a combination of Avon River catchment flooding and sea flooding.

2017 Coastal Hazard Assessment appendices

You can view coastal erosion hazard maps in appendix H, and coastal flooding maps in Appendix I.

Appendix Title Description
A

Site location plan [PDF, 2.2 MB]

 Coastal areas of Christchurch covered by the 2017 Coastal Hazard Assessment Report
B Beach profile output plots [PDF, 1.5 MB] Beach profiles for 26 locations from Waimairi Beach to Southshore from 1990 through to 2016
C SBEACH assessment [PDF, 126 KB] SBEACH is a model that defines storm-cut beach material volumes and the horizontal movement of the toe of dunes. Appendix C gives the SBEACH results, used in the coastal hazard erosion assessment.
D Storm cut matrix [PDF, 389 KB] Inter-survey storm cut distances since 1990 along the open coast (excluding Sumner) in southern Pegasus Bay.
E DSAS maps including beach profile locations [PDF, 17 MB] Digital Shoreline Analysis System (DSAS) is a model used to evaluate long-term shoreline trends.  Presents maps showing the rate of shoreline change at 10 metre intervals along the open coast, and the location of the beach profiles, along with shoreline positions from 1940 to 2010 with respect to the 2011 shoreline.
F Assessment of input parameters for long-term distribution [PDF, 276 KB] Detailed explanation of the methods used to determine the long-term rate of coastline movement.
G Site specific assessments of the Lyttelton and Akaroa Harbour environments [PDF, 3.3 MB]  Site inspection and aerial photograph information specific to four bays in Akaroa Harbour (Wainui, Duvauchelle, Takamatua and Akaroa) and four bays in Lyttelton Harbour (Alandale, Teddington, Charteris Bay and Purau).
H CEHZ result maps [PDF, 209 MB](external link) Coastal erosion hazard zone maps for the open coast and harbour coasts (the Avon-Heathcote Estuary and Brooklands Lagoon, and Banks Peninsula). Please note a correction to Figure H-38in the report:  The line type (seawall) shown at the Bridge Street bridge is incorrect.  The line shown at the bridge represents the practical ‘upstream’ extent of the coastal hazard inundation modelling where inundation from the sea is likely to dominate flooding derived from catchment flooding.  Further upstream flooding is a combination of Avon River catchment flooding and sea flooding.  Flood hazard information for the Avon River catchment flooding in South New Brighton and Southshore is available here. 
I CIHZ result maps [PDF, 106 MB](external link) Coastal inundation hazard zone maps for the open coast and harbour coasts (the Avon-Heathcote Estuary and Brooklands Lagoon, and Banks Peninsula).
J TUFLOW model description [PDF, 482 KB] Description of the TUFLOW model used to more accurately define potential coastal inundation in low-lying and wide flat areas.
K Open Coast CHEZ probabilistic model outputs [PDF, 772 KB] Full set of  the histogram and cumulative distribution function graphs from the probabilistic assessment output for each site along the open coast for the average sediment budget and reduced sediment budget scenarios

You can also view the presentation [PDF, 1.4 MB] from the Council meeting on 9 November 2017 where the 2017 Coastal Hazard Assessment was received. 

2015 Coastal Hazard Assessment

The 2015 Coastal Hazard Assessment [PDF, 12 MB] identified areas susceptible to coastal flooding and erosion for the main coastal settlements in the Christchurch District over both a 50 year (2065) and 100 year (2115) timeframe.

A peer review of the assessment methodology and reporting was undertaken by Hume Consultancy Ltd.

All the suggested amendments documented in the peer review were included in Version 2 of the Assessment.

2013 Coastal Hazard Assessment

The 2013 Coastal Hazard Assessment [PDF, 14 MB] undertook a sea level rise literature review, provided an assessment of the effects of land movement due to the earthquakes on coastal processes, provided an assessment of the impacts of sea level rise, and identified possible mitigation solutions for the potential impacts of sea level rise.

1999 Coastal Hazard Assessment

The 1999 Coastal Hazard Assessment [PDF, 819 KB] gains an overview of potential effects of sea level rise on Ōtautahi Christchurch based on best knowledge at the time.