Restoration and Betterment of a Unique Christchurch Waterway Catchment Post-Earthquake

The Christchurch earthquake series caused widespread land damage across Christchurch City, including damage to the city’s waterways. Impacts on the city’s waterways included bed heave, settlement, liquefaction and lateral spread of banks. Pattle Delamore Partners Ltd were engaged by Christchurch City Council to undertake a series of investigations to determine the extent of earthquake damage and its effects on the “six-values” (capacity, ecology, landscape, recreation, heritage and culture) in the Wairarapa Stream and Wai-iti Stream. The ultimate purpose of this project was to identify options to remediate these unique and valuable waterways to pre-earthquake condition, and identify opportunities for longer-term improvements.

In conjunction with site visits and stream surveys, a hydraulic capacity model of the streams was built using the MIKE modelling software. The purpose of the model was to identify and compare areas where post-earthquake capacity no longer meets the preearthquake capacity. This paper examines how the site visits, stream surveys and hydraulic model were used to develop options for longer-term betterment which would enhance all six values.