Chapter 17 - Natural Hazards obligation to carry out regular maintenance to minimise storm damage costs and closure times. Although much is known about the different types of land failures which affect different parts of the Wairau/ Awatere further research is required in order to develop a more comprehensive picture of the risks associated with different kinds of slope failures. In particular research is required to establish: • Historical Data Base Collation of records of past rainstorm-generated slope failures, with a view to gaining a better understanding of frequencies and triggering rainfalls. • Rainfall Records The extreme variability in magnitude/ frequency/ duration for different parts of the Region requires assessment. • Threshold Moisture Levels Determination of threshold soil moisture levels for the loessial soils of the Wairau Catchment is needed, with a view to providing emergency services warnings when widespread slope failures can be anticipated. • Landslide Hazard Zoning The zoning of areas according to risk of slope failure is also required, with priority being given to the Wither Hills area because of the greater urban population involved. • Landslide Monitoring Existing landslides which move in response to increases in soil moisture should be monitored on a regular basis to provide an improved data base, and to facilitate remedial measures. • Vulnerable Localities Areas at risk from slope movement and extensive soil erosion hazards, specifically transportation routes and population centres, should be identified in consultation between Transit New Zealand, Tranz Rail and the Council. 17.5.2 Objectives and Policies Objective 1 Avoid loss of life, and avoid, remedy or mitigate damage to property and infrastructure as a result of slope instability. Policy 1.1 Locate works and structures to avoid their damage from the effects of slope instability. Policy 1.2 Establish and maintain protection works designed to avoid, or mitigate the effects of natural hazards, where the benefits outweigh the costs. Policy 1.3 Define areas at risk from slope instability, including sea level rise, within a Natural Hazards Register to assist future sustainable management of resources. 17 - 11