Chapter 17 - Natural Hazards Zoning Zone land within the floodways and identify land on which significant flooding is known to occur as a flood hazard area with appropriate rules. Designations Floodway land will also be designated as required for river control works so as to control activities such as tree planting which might impair the functioning of the floodway. Rules For defined flood hazard areas rules will be used to ensure damage from the flood hazard is avoided by sensible location of structures outside the identified area or, to minimum floor levels. Monitoring Monitor the performance of the floodway system by measuring size of floods, recording flood levels along banks, inspecting banks for erosion damage and survey of flood events, especially following major floods. Regularly re-survey river channel bed levels and re- analyse the effects of changed channel conditions on waterway capacity. Use monitoring information to review expected flood size from time to time. Information Develop an information database relating to the location and extent of the flooding hazard. Education Promote community understanding of the severity of the flood hazard on the Wairau floodplain, of Wairau tributaries and other flood prone rivers. The historical modification for flood control purposes of the inter-related watercourses of the Wairau floodplain (below Waihopai confluence) is irreversible. The maintenance and upgrading of the river control floodways has to remain the primary method to reduce the flood hazard here. This is a public work that has to be done by the Council to a comprehensive and integrated plan. Even so there will be identifiable areas on the floodplain where the costs of flood control works exceed benefits and flood hazard avoidance measures are preferable. The efficient and effective operation of the floodways, many of which are on private land, may be compromised by activities of other parties. Defining acceptable activities within defined floodway zones will help maintain floodways to an effective standard. Outside the main Wairau floodplain the costs of structural flood hazard avoidance measures usually exceed the benefits. Here the location of houses and structures where they will not be damaged will be a more effective method of reducing loss and sustaining development. An information base on the frequency, location and extent of the flood hazard is required in the design of the Council flood control works; in the delineation of flood hazard areas and in rules for flood hazard areas and other zones. 17 - 7