Wairau/ Awatere Resource Management Plan Simplified Hazard Evaluation for the Wairau/Awatere Likely Exceedence Interval Hazard Category Less Than 100 Years Greater Than 100 Years Seismic Ground shaking and local damage Ground rupture on Wairau Fault to small magnitude (M<6.0) event or Alpine Faults with L within District, or to large accompanying large magnitude magnitude (M>6.0) event outside (M>6.9) earthquake effects in L L the District. Blenheim. Subsidence or raising of land resulting in change to drainage pattern and potential flooding from rivers or sea. Note: Major forest fires in rural areas are excluded from classification, but can be expected to have a recurrence interval of less than 100 years. 17.2 Meteorological 17.2.1 Issue Adverse effects arising from extreme meteorological events. There are a number of meteorological events which have the potential to cause damage and destruction and for which little can be done. These hazard events which warrant consideration are damage by snowstorms, windstorms and drought. Windstorms can result in damage to exotic forests and structures, stock losses (in conjunction with heavy precipitation) and loss of topsoil (losses of up to 5 tones/ hectare have been calculated in extreme events). Dealing with the effects of windstorms requires appropriate responses in terms of structural standards for wind loading and emergency preparedness. Further research is required to assess actual damage that occurs in this part of the district due to extreme wind to determine the value of developing mitigation strategies. Snowstorms can result in large stock losses, damage to horticulture and disruption of road, rail and other communication systems. Drought may be defined in many different ways. Easiest of all is by applying the concept of “lack of rainfall”. If agriculture is the primary concern then “soil moisture deficit” might be a more appropriate measure. In a hazards context, the way in which a population is able to adjust to drought potential is a factor of importance when considering the question of risk and need for a response. Nevertheless the impacts of severe droughts are generally widespread and the cost to the district often becomes difficult to separate from the cost to the Country. The greatest losses usually occur in agriculture and power generation. Because drought develops relatively slowly, is long lasting and often widely dispersed in extent, the range of immediate and appropriate options is limited. The most pressing need is for improved forecasting for both seasonal and several year time scales, and the use of this information. Such information should be built into strategic management strategies such as water storage and augmentation schemes and the encouragement of flexible agricultural regimes. 17 - 2