Historic Christchurch City Council Benchmark Network
Historic Christchurch City Council Benchmark Network
Created by: Christchurch_City_Council
Last updated: Thursday, August 7, 2025
Description
NOTE: Christchurch City Council has officially adopted New Zealand Vertical Datum 2016 (NZVD2016) as its standard for height measurements. This marks the formal retirement of Christchurch Drainage Datum (CDD), which played a pivotal role in the region’s surveying and civil engineering history for the last 149 years. Formerly used for site level control and drainage infrastructure, CDD benchmark data is now retained solely for historical reference. Please be aware that CDD benchmarks are no longer physically maintained by Council.
NZVD2016 benchmark data is available at LINZ Geodetic Database
22 July 2025
What Are Benchmarks?
Benchmarks are levelled survey points assigned heights expressed in terms of a common datum (reference surface). In the case of Christchurch City Council, the datum used is known as Christchurch Drainage Datum (CDD).
What Are Benchmarks Used For?
Christchurch City Council Benchmarks enable the ready establishment of normal-orthometric heights in terms of CDD within the greater Christchurch area. For example; a benchmark would be used to physically establish design ground levels for subdivisions, invert levels for pipe works and specified floor levels for new buildings in terms of CDD.
History
The origin of CDD dates back to February 1876, the early days of the Christchurch Drainage Board where the need for a common level was evident very early in the quest to control Christchurch's drainage issues. An arbitrary figure of 50 feet (15.240m) above datum was chosen for the networks fundamental benchmark (A82), which was situated in the floor of ChristChurch Cathedral’s foyer. A value of 50 feet ensured that levels specified on engineering works in Christchurch City would be expressed as positive values, even when working in New Brighton and Sumner where infrastructure is often situated below sea level.
The earthquakes experienced in the Canterbury region between 4 September 2010 and 23 December 2011 put the integrity of the Council’s network of benchmarks in doubt. In response to each of the seismic events interim “emergency response” benchmark networks were established using Global Navigation Satellite System technology. A “recovery response” precise level network was established in January 2014 when seismic activity was believed to have subsided to a permissible level.
Fundamental Benchmark
The level value for A82 is now of historic interest only. It had a recorded height of 20.333 feet (6.197m) above Lyttelton Vertical Datum 1937 (mean sea level 1937) prior to the 4 September 2010 Darfield (Canterbury) earthquake. Land Information New Zealand’s Hagley Fundamental (AF30) has been adopted as the new fundamental mark for Christchurch Drainage Datum. The offset from Lyttelton Vertical Datum 1937 to Christchurch Drainage Datum is 9.043m.
What's In A Name?
Christchurch Drainage Datum was initially called Christchurch Drainage Board Datum but upon amalgamation of the Drainage Board and it's activities into the Christchurch City Council the name was changed to Christchurch Drainage Datum (CDD).
The Current Network
The new July 2019 Network replaces the January 2014 network, containing revised level values to account for the deformation caused by the 2016 Valentine’s Day earthquake and the 14 November 2016 magnitude 7.8 (Mw) Kaikoura earthquake. Level values were adjusted by Land Information New Zealand using LINZ reverse patch update version 20171201.
Map Credits
Christchurch City Council, Environment CanterburyAccess and Use Constraints
Any information, maps or data ("information") provided by the Christchurch City Council in association with this website is on the following basis:
- The preparation and provision of information has been made in good faith from a number of sources believed to be reliable.
- Reduced levels are normal-orthometric heights in terms of CDD.
- Benchmarks are current as at the date this website is accessed. The information supersedes any previously published information.
- Christchurch City Council shall continue to update Benchmarks and reserves the right to to add, remove or amend Benchmarks without prior notice.
- Any aerial imagery or geodetic codes provided as part of the information, may not be current. Interested parties should obtain their own advice to ensure the accuracy of aerial imagery and geodetic codes.
- Grid coordinates have been provided for location purposes only and should not be relied on without further investigation.
- Christchurch City Council makes no representation and provides no warranty, express or implied, regarding the accuracy, adequacy, reasonableness or completeness of the information contained or referred to in this website or in any supplementary materials. Christchurch City Council disclaims all liability and responsibility (including, without limitation, any liability arising from fault or negligence on the part of the Christchurch City Council) for any direct or indirect loss or damage which may be suffered by any recipient of the information in this website or any supplementary materials, through use of or reliance on or in connection with anything contained in, or omitted from, such information or materials, to the maximum extent permitted by law.
- The information should only be used for the purposes of determining Benchmarks and for no other purpose without prior written consent from Christchurch City Council.
Please address queries and feedback to benchmarks@ccc.govt.nz
To Subscribe to
Council benchmark network notices please click here
To view in a free client like Google Earth or ArcGIS Explorer as KML please click here
Map Contents
- {{layersInfo.baseMap.title}}: {{layer.url}}{{$last ? '' : '; '}}
- {{layer.title}}: {{layer.url}}