Wairau/Awatere Resource Management Plan 23.2.1 Objectives and Policies Objective 1 That subdivision proposals be carefully assessed in localities where there are significant natural hazards, unless the effects of these can be adequately avoided, remedied or mitigated, and any such mitigation measures do not have significant adverse effects on the environment. Policy 1.1 Control subdivision of land subject to natural hazards such as inundation, erosion, subsidence, slippage and rock fall. Policy 1.2 Ensure that subdivision does not take place in a manner which could lead to land, waterways or drainage channels being placed at significant risk from sedimentation or scouring of river banks. Policy 1.3 Ensure that the adverse effects on the environment of measures to mitigate the effects of natural hazards on land subject to land subdivision are avoided, remedied or mitigated The Council has an obligation under Section 106 of the Act to decline consent to any subdivision in areas where these hazards cannot be adequately mitigated. Where mitigation measures are employed it must be ensured that they are in fact adequate to overcome the hazard. It is also necessary to consider the effects of the mitigation measures themselves which may also create adverse environmental affects. An example of this is the filling of land which may interfere with the functioning of natural flood plains or ponding areas. Much of the Lower Wairau is particularly vulnerable to potential flood hazard. There are also areas adjacent to the coastline which are anticipated to be subject to sea level rise over the longer term. The subdivision of land in some areas subject to potential flood hazard may be able to be overcome by the provision of works, or by the provision of standards relating to, for example minimum floor levels. However, the Council will ensure that in assessing subdivision applications in such areas, the intensity of subdivision is not such that it would give rise to relatively high densities of building activity on land subject to flooding or inundation. This is particularly important in the case of subdivision and the potential for dwellings in the rural area. Areas subject to potential sea level rise are likely in some cases to be protected by works, but there are areas where the cost of such protection would be prohibitive in respect to existing investment. Subdivision of land within areas subject to likely sea level rise will be discouraged should they contain proposals for intensive subdivision and associated investment in structures. There are many areas within the Wairau/Awatere which are particularly prone to erosion, and small areas are subject to slippage and rock fall. Here the concern is with the suitability of such land for subdivision at all, or whether portions of land should be excluded from subdivision to ensure subsequent land use activities involving buildings are not exposed to undue risk to life or property. Subsidence can similarly be a factor, particularly on land filled with unconsolidated material. It is usually possible to mitigate adverse effects caused by flooding, subsidence, slippage, alluvium (sediment buildup), avulsion (loss of land into a river) or erosion through the undertaking of various engineering measures. These measures may however have significant adverse impacts in themselves. 23 - 2