The MacGillivray/Haines district on Kangaroo Island has topography whereby surface water runoff from the surrounding catchment is collected by a number of lagoons, with no outfall to the ocean. This area experienced a significant rainfall event in June 2013, the impact of which was compounded by above average rainfall recorded for a number of months for that year. The event resulted in elevated water levels within numerous lagoons that inundated public roads and access into properties, inundated agricultural land and prevented access to some tourist/accommodation destinations. The damage resulting from this event has been estimated to total $10 million.
In response to the 2013 event, the Kangaroo Island Council, Island Agencies, Emergency Services and local community members formed the Kangaroo Island Flood Recovery Committee. The Committee recently engaged Southfront to develop a Flood Mitigation Options Study, in order to assess whether there are any practical options to lessen the effects of similar events in the future.
The Study is proving to be an extremely interesting and unusual technical challenge. The flood impact is different in that it occurs over an extended period – measured in months to years – and the sheer quantity of floodwaters and unfavourable terrain are such that conventional flood mitigation responses would be on a far greater scale than that which is commonly contemplated in South Australia. The Study is making use of high resolution digital terrain models and aerial photography to better understand the scope of the problem, to identify what works might be reasonable, and what other supporting land use strategies might be required.