Northland Civil Defence Emergency Management Plan, 2010

the failure is prolonged, there could be severe economic and social consequences.Human pandemic; the scenario evaluated was based on modeling that predicts a worst-case event with thefirst wave seeing 40% of people becoming ill in the first 8 weeks and 2% of these resulting in death.The next level of risk is posed by:A local volcano in the Bay of Islands which, while a relatively low probability event, could cause permanentdisplacement to people in a localised area and possibly have a significant impact on tourism and theNorthland economy.Telecommunications failure: The telecomms networks have more diversity than electricity or fuel andtherefore a lower probability of widespread failure, however the consequences on the economy are alsopotentially significant.Drought: A drought affecting the agricultural community could have major economic consequences. A worstcasescenario in an urban water supply drought is one which disrupts supply to the refinery (which relies onmains water supply to operate).2007 March and July flood eventsDuring both the March and July 2007 storms a low pressure system developed in the northern Tasman Sea andwas ‘blocked’ by high pressure systems further to the east of the country. This scenario caused a strengthening,very slow moving, northeast flow onto northland which caused heavy sustained rainfall.In the March storm, extremely heavy rainfall occurred over the eastern side of Northland with some rainfall totalsfor the two days exceeding 400 mm and in excess of 1/100 AEP 1 estimates (1 in 100 year return periods). Thisresulted in record high river flows in some east coast rivers and people were stranded by flood waters. One localBay of Islands woman was rescued by fire crew and volunteers from a tree above a swollen river.The July storm rainfall totals were less than those experienced during the March event, with only a few locationsrecording rainfall totals greater than 300 mm. However rainfall was more widespread across Northland with muchof the region receiving more than 100 mm in two days.The July storm was also associated with severe northeasterly gales which caused power outages across the districtwith gusts of up to 125km/hr recorded at Dargaville. The combination of gale force winds and high tides causedsignificant storm surge along the east coast.A state of local emergency was declared in the Far North district with 160 people being displaced at the height ofthe storm. Communities on the coastbecame stranded with roads beingblocked or washed away. Utilitiessuch as phone, power, water andsewage were cut and some areas inNorthland experienced a loss ofelectricity for up to 7 days. Extra staffhad to be brought in from otherregions to restore power toNorthland.There was no loss of life during eitherweather events but there wereseveral lucky escapes in hazardouscircumstances and many people werecaught unprepared.Damage to Old Russell Road, HelenaBay March 20071 An AEP is the annual excedence probability which is the probability of an event of a particular magnitude(characterised by a rainfall depth or peak flood size) being exceeded in any year.Northland Civil Defence Emergency Management Plan, 2010-2015 Page 22