Site Visit One – Success Stories/Case Studies – Waterways
Kopurererua Wetland Restoration
The biggest wetland restoration project in the southern hemisphere. This is a 20-year project to transform 300 hectares of Kopurererua Valley from rough farmland into a natural landscape, including realigning the Kopurererua Stream back to its meandering course. The stream was straightened into a farming drainage channel at least 50 years ago, causing much distress to Maori because it was central to the hapu’s life and legend. An example of the community working together with the Council.
The Hairini wetlands, near the Maungatapu underpass, an NZTA run collaborative project where the expansion and restoration of two Tauranga wetlands will see more than 60,000 plants planted over the next five years on 50,000m2 of wetland at Ila Park and Hammond Street Reserve. During this time, the new business collective of three local hapu Te Ropu Aonui Hou will manage the restoration, including removing invasive weeds and non-native plantings, pest management, as well as the planting and care of the 60,000 new plants.
Te Ara o Wairakei
Tauranga City Council is implementing Te Ara o Wairakei – a project to enhance approximately 10km of stormwater drainage reserve in Papamoa. The Wairakei Stream has been heavily modified with land development over the last century and is the main stormwater receiving environment in Papamoa. Council worked with tāngata whenua and the community to implement a plan to restore native habitats, provide cultural acknowledgement and construct walkways and cycleways along the reserve. In this site visit, we’ll explain the history of this area and how this area has been transformed to improve stormwater management and recreational amenity.
Site Visit Two – Stormwater Management – Design Approach Innovation & Technology
Tauranga flood hazard mapping and solutions
In 2015 Tauranga City Council adopted a ‘safety to persons’ focussed Level of Service (LoS) as part of its approach to flood risk management. This approach provides for a reduction in risk to persons, rather than the more traditional approaches which focus on the protection of land and/or buildings. At-risk properties under the LoS are defined as those where a depth x velocity threshold of ≥0.4m2/s is exceeded within 8m of a building with a habitable floor for residential and rural-residential zoned private property, and ≥0.6m2/s for non-residential and non-rural residential zoned private property. At risk areas were identified through city-wide 2D hydraulic flood models which were then used as the basis for undertaking optioneering studies which considered methods to achieve flood reduction whilst considering resilience, safety, WSUD and other social or environmental benefits. This fieldtrip includes stops at four locations where solutions have been or will be implemented, showcasing the different approaches that can be used.
This is a project to upgrade the street to make it pedestrian/cycle friendly and link with new University of Waikato campus. It includes raingardens with soakage and also overflow into stormwater system, separate tree pits to allow easier renewal of rain garden media in the future, and it aims to treat stormwater to remove pollutants flowing into the nearby harbour. The street also has stormwater filters (at Elizabeth Street end) due to potential bus interchange.
Site Visit Three – Naturalising Te Ao Māori values
Kaituna River Re-diversion
The goal of the Kaituna River Re-diversion Project is to significantly increase the volume of water (particularly fresh water) flowing from the Kaituna River into Te Awa o Ngātoroirangi/Maketū Estuary in a way that maximises the ecological and cultural benefits (particularly wetlands and kaimoana) while limiting the economic cost and adverse environmental effects to acceptable levels. The $17M project was planned and designed following decades of estuarine degradation in response to drainage and flood protection works since 1956. The 12 new box culverts with hydraulically powered vertical slide gates provide 75m2 of cross-sectional hydraulic capacity, which will allow 600,000m3 of water to flow from the Kaituna River into the estuary on average tides and with average river flows. The effect of this is to replace the tidal prism volume in Maketū Estuary every 2.5 tides, rather than every 15 tides as was the case between 1956 and now. Project Manager Pim de Monchy will discuss the modelling and engineering behind the project, as well as the cultural, ecological and social context for it.
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