Aerial view of Kai Iwi Beach (Mowhanau)
Why we need to take action on our coast
Whanganui has a spectacular coastline which holds special significance for many of us. We want to take care of it for our community now and for coming generations. The key challenges facing our coast are erosion, significant natural sand movement and ecological degradation. These challenges are expected to grow as a result of climate change.
Castlecliff
To start with we are prioritising work in two areas of Castlecliff Beach – the North Mole and the Rangiora Street beach area. Works have been approved and are already underway for the North Mole. We will engage with community on the Rangiora Street area again in 2026.
Note: South beach area will be investigated for inclusion in the work programme after 2026.
Timeline
2022
- Early discussions and workshops with community and stakeholders, including a coastal survey which 505 people responded to.
- Management options developed for Castlecliff Beach.
2023
- The council endorsed community and hapū collective Nga Ringaringa Waewae to lead community engagement on a conslidated vision for Castlecliff (including the Coastal Action Plan work and a proposal to rejuvenate the North Mole area).
- Community engagement at Castlecliff (through focus groups and events led by Nga Ringaringa Waewae). Note: you can read about the outcomes of this engagement and a rejuvenation plan for the North Mole here
2024
- Funding approved for the Coastal Action Plan dune restoration and North Mole works through council’s Long-Term Plan 2024-2034
- Completion of a foredune restoration plan for the North Mole area.
- Dune planting begins at the North Mole.
2025
- Installation of a new foredune and carpark scheduled for the North Mole area.
2026
- Community engagement on options for the Rangiora Street beach area.
Beyond 2027
- Delivery of the agreed next steps for the Rangiora Street beach area (subject to council funding and approval).
Mowhanau/Kai Iwi Beach
Kai Iwi Beach is a naturally eroding coastline and this erosion is likely to speed up as a result of climate change. In the short to medium term, a worsening of coastal storm events may pose a threat to Archer’s Bridge and the beach access it provides. In the longer term (over the next 100 years) erosion poses a threat to council assets (such as the carpark and toilet block) and to a small number of residential Mowhanau properties and roads. The level of threat anticipated over this timeframe will depend in part on the management approach which is used.
The council’s work at Kai Iwi Beach is focusing on an adaptation plan in line with Ministry for the Environment guidelines. This plan will lay out possible management pathways for the future and provide guidance on when we need to change our approach and how to decide which approach to take. Over the next three years, the council will continue to maintain the existing rock revetment at Kai Iwi Beach, which has been successfully managing erosion to date.
Next steps for Kai Iwi
In early 2024 we commissioned an updated erosion hazard and risk assessment report from Tonkin and Taylor. Following the return of this report we will host a community meeting to outline the report’s findings and the proposed next steps for this work.
Beginning in 2025, a series of future oriented workshops will take place where community can contribute to both the adaptation plan (looking at how we respond to erosion) and a community spatial plan (which will look more broadly at the growth and development of Kai Iwi Beach into the future).