Waterway assessments
Some of the spring-fed waterways across Kaikōura received extensive damage during the 2016 earthquakes. Bank slumping, riparian area lateral cracks, blocked drains, and increased sediment were all issues that had potential to cause ongoing problems to water quality if no remediation was identified.
Background
NIWA field trip to gather data that informed a report on recommendations for whole-catchment recovery
In January 2017 a stream walk along Lyell Creek / Waikōau and its connected drains was carried out, to collect information on the post-quake state and health of the catchment.
The stream walk was completed in teams of two, each team covering separate sections of Lyell Creek/Waikōau and its surrounding waterways.
The teams walked along the stream banks, in the stream, and in nearby drains, examining and recording information on:
- weeds, stream bed cover, and stream life
- vegetation along the stream banks
- signs of erosion next to the stream
- obvious earthquake damage, and
- opportunities for improvement.
The goal
Lyell Creek/Waikoau flowing adjacent to the main street of Kaikōura
The purpose of the stream walk was to gather information that would provide an overview of whole catchment recovery (as opposed to recovery for individual waterways), and identify areas where the team could best focus Kaikōura Plains Recovery Project (KPRP) funding, resource and advice.
Alongside the identification of target areas, the goal was to create a database of information on the catchment and its habitat, to inform KPRP and other agencies of any changes post-quake, and to create a baseline for change over time.
All information collected helped KPRP see where action was needed. It continues to guide a whole catchment approach adopted by our staff in Kaikōura.
The outcome
The survey helped identify hot spots for action and went on to form two reports (issues and recommendations) that were compiled by the National Institute of Water and Atmospheric Research (NIWA).
These reports helped provide the information needed for a whole catchment recovery approach and allowed KPRP to identify key areas of focus, including support for local farmers wanting to manage critical source areas, and explore new ways of operating to improve water quality.
Water testing being carried out by staff in the catchment
Alongside KPRP's collection of stream data, our scientists were undertaking further research to provide water quality updates to KPRP, and to collaborate on whole catchment recovery.
Research work included:
Lyell Creek/Waikōau and its catchment on the east coast of the South Island
The first report produced by NIWA with the stream data, focused on the main issues facing Lyell Creek/Waikōau and its connecting waterways.
Main issues identified for water and habitat quality:
- high sediment content in the stream bed
- bank erosion
- reduced macro-invertebrate quality
- poor stream health, with elevated concentrations of nitrate and dissolved reactive phosphorus
- new springs appearing in farm paddocks
- overland flow paths emerged, carrying runoff water from paddocks to waterways
- slumping of stream banks
- reduced shade over water due to riparian vegetation removal.
Lyell Creek/Waikōau values impacted:
- aesthetic quality of the stream network
- ecosystem health
- recreational values.
Taking a whole catchment approach to post-quake recovery will help to improve water quality in Lyell Creek/Waikōau (pictured) and its tributaries
The second report produced by NIWA provided recommendations for a whole catchment recovery approach. This was requested by KPRP to help guide their work in improving water quality and in-stream ecosystem health for Lyell Creek/Waikōau and its connecting waterways post-quake.
Recommendations to improve water and habitat quality, restore aquatic flora and fauna and reconnect people with the creek:
- conduct baseline monitoring to identify potential additional issues and determine specific locations of known issues
- deal with critical source areas
- gradually plant riparian areas, beginning with places most visible to the community and greatest habitat value for native fish
- remove or remediate any migration barriers for native fish
- enhance instream habitat for native fish and invertebrates
- remove legacy sediment
- gradually replace willows with native trees
- construct walkways and access points.
The recommendations report continues to assist organisations and landowners in the area, who are undertaking work to enhance and improve water quality.
