11. Natural Hazards Volume One river channel edge. For other rivers, it is necessary for vegetation to be removed to provide for the free flow of flood water. Access to carry out river control works in the channel, such as gravel extraction, rock placement, aquatic vegetation removal or stop bank maintenance, may also be required. Council control of vegetation and access to and along a river bed can therefore be important. Vegetation control and access can be achieved through the creation of esplanade reserves and esplanade strips as part of the subdivision consent process. The waterbodies identified in (a) and (b) are those where multiple landowners or a community would benefit from the flood mitigation works identified above. In this way, the policy acts to provide greater certainty about when the Council will utilise the esplanade reserve provisions of the RMA for flood hazard mitigation purposes. [D] Policy 11.2.5 – The width of any esplanade reserve or esplanade strip set aside for flood hazard mitigation shall generally be 8 metres, except on land adjoining the Wairau River, Omaka River, Waihopai River, Pelorus River or Rai River, where the width shall be 20 metres. Under the RMA (Section 230), esplanade reserves of 20 metres width are required where any allotment of less than 4 hectares is created when land is subdivided. The Council has the discretion to vary this requirement for esplanade reserves or strips. The policy identifies that in many circumstances a reduction in width is appropriate if the reserve or strip is being taken for flood hazard mitigation. In most circumstances, 8 metres is sufficient to undertake river control works and to access the river for this purpose. Exceptions are set out in the policy and include larger rivers which, because of their scale, require a wider reserve or strip to undertake river control works. Regard should also be had to the special circumstances identified in policies in Chapter 15 - Resource Quality (Water, Air, Soil), Chapter 8 - Indigenous Biodiversity and Chapter 9 - Public Access and Open Space. [R, D] Policy 11.2.6 – When considering any application for resource consent or notice of requirement for hazard mitigation works, have regard to: (a) the likely effectiveness of the mitigation works and the residual risks remaining after mitigation works are in place; (b) whether non-structural or soft engineering methods are a more appropriate option; (c) the cumulative effects of isolated structural mitigation works; (d) any adverse effect on existing hazard mitigation works; (e) responsibility for the ongoing maintenance of the mitigation works to the required standard; and (f) the method and effects of construction on the surrounding environment. Although hazard mitigation works act to protect the community, the construction and ongoing presence of these works can themselves have adverse effects on the environment. Where they involve substantial modification to the natural character of the waterbody, these effects can be significant. Recognising the potential for adverse effects, this policy provides direction to ensure that any proposed new works are effective in the first instance and that the method of hazard mitigation is the most appropriate. These principles can be applied when processing resource consent applications required to undertake the work or any notice of requirement application to provide for the work. This will ensure that any adverse effects, including those on existing hazard mitigation works, are avoided or mitigated, and that mitigation works are maintained in an effective state on an ongoing basis. 11 – 12