Infrastructure Strategy Options to address it Implications of the options (financial and non- Options to address it Implications of the options (financial and non- financial) financial) damage only Avoids capital costs of upgrades. Costs of managed retreat. Costs Possible reputational damage from flood damage. Additional damage to wave band protection and adjacent land. Additional remedial costs and maintenance. 3 Most likely scenario Loss of some existing land uses over time. In 2019 the Council will start the review the core Wairau River Floodway Management Plan, and take climate change into account as well as the 25 years of additional flow data records collected since the plan was originally prepared. Once the flood risk data has been updated the Council will undertake a major public consultation exercise with Potential impacts of climate change on flood flows the key stakeholders on an updated plan for the key Wairau works through to 2050. The objective is to gain more understanding of the desired level of service and Options to address it Implications of the options (financial and non- willingness to pay for future flood protection works. financial) PREFERRED OPTION Benefits The current thinking is that relatively minor upgrades will be required to preserve existing levels of service to about 2050 but after that time other options, including Community involvement in decision-making. accepting increased flood risk or retreat from some very low lying areas, may need to Undertake a Retains ability to adapt to changes over time. be considered. comprehensive review of Include the most recent climate change projections and This plan is likely to be implemented through a range of activities including building the Lower Wairau Flood high quality hydraulic modelling. and maintaining stopbanks, river diversions, detention dams, stopbank erosion Protection Scheme protection (rock and trees), river channel clearing, channel excavation, channel including climate change Decision making using high quality information. training, and use of flow control gates. scenarios and to consult with the community on Costs both the desired levels of Consultancy costs to perform analysis and modelling. A climate change allowance is already built into all current Blenheim stormwater flood protection and their design and planning. The flood risk associated with the Picton rivers was recently willingness to pay. Potential delay in decision making. reviewed, following the very large Waitohi and Waikawa River floods in 2004. Financial and practical resources will be required for In Picton, further upgrade of the Waitohi triple culverts will be required to meet the monitoring and for adaptation to changing flood flows desired 50 year flood standard. This work can only be cost effectively completed if it and frequencies of flood events. can be fitted in with upgrade plans within the KiwiRail shunting yard and Interislander Accept lower levels of Benefits parking area. flood protection over time Recognises ongoing and increasing nature of climate in areas where climate change. In the interim, the flood hazard risks in the Dublin Street area and adjacent to the Kent change increases the Street drain (Buller Street branch), will be identified in the Council’s hazard register, magnitude and frequency Costs with some building restrictions applying to this area (mainly minimum floor levels). of flood events. Flood damage to private property and public Over the longer term, further investigation of upgrading costs and also of possible infrastructure. funding sources for these upgrades is required as a part of the planned review of the Loss of some existing land uses over time. Wairau River Floodway Management Plan followed by discussion with the affected community. 2018-2028 Long Term Plan Page 211