Queensland flooding health risks

by Jeni Bone on 11 Jan 2011 Along with loss of property, possessions and lives, the flash flooding in Toowoomba and other regions in Queensland will have massive impact on the state's economy and the health of its residents, according to scientific experts.

Commenting today on yesterday’s flash flooding in southern Queensland which has left at least eight people dead and more than 70 others still missing, Tony Weber, National Practice Leader - Water Quality for BMT WBM (Engineering and Environmental Consultants) and Visiting Fellow at the Integrated Catchment Assessment and Management Centre, Fenner School, Australian National University, believes there is a risk of more major runoff events.

'With the whole catchment now in a state of complete saturation, any subsequent rainfalls, even though they may not be record rainfalls, will likely result in extreme runoff events as we have seen in Toowoomba and the Lockyer Valley. Until sufficient drying of the catchment occurs (likely to be in the order of several weeks with no further major rainfall), there will continue to be a very high risk of further major runoff events.'

Professor Neville Nicholls, an Australian Research Council Professorial Fellow in the School of Geography & Environmental Science at Monash University and President of the Australian Meteorological and Oceanographic Society, says the conditions that come with La Niña are to blame.

'The Queensland floods are caused by what is one of the strongest (if not THE strongest) La Niña events since our records began in the late 19th century http://www.amos.org.au/news/id/105

Our understanding of the La Niña and its impacts meant that the Bureau of Meteorology, as early as October, was warning of substantially increased chances of above average rain across eastern Australia

http://www.bom.gov.au/climate/ahead/archive/rainfall/20100923.shtml.

The La Niña is also associated with record warm sea surface temperatures around Australia and these would have contributed to the heavy rains. The extent to which any of this (the floods, the warm oceans, or the very strong La Niña) is linked to global warming is unknown, because the requisite studies to test this have simply not been done yet.'

According to Professor Tony McMichael, a Professor and NHMRC Australia Fellow in the National Centre for Epidemiology & Population Health at The Australian National University, disease and post-traumatic disorders are now concerns for Queenslanders, those affected directly and indirectly.

'There is an increased risk of outbreaks of Ross River virus and dengue infections in post-flood Queensland, particularly in these warm and humid conditions. Mosquito populations will now have much greater breeding opportunities. (Whereas the Ross River virus is endemic in Queensland, outbreaks of dengue require 'seeding' of the virus into the population - usually from a returned overseas traveller.)

More generally, the risk of epidemic infection outbreaks after such disasters is proportional to the disruption of natural and built environments, human population crowding and contact, and displacement of communities. From flood experience elsewhere the most frequently reported outbreaks are:
* Diarrhoeal (gastroenteritis) diseases
* Respiratory illnesses (prominent after Hurricane Katrina in the USA)
* Skin infections

'Flooding also has a range of adverse effects on mental health. Long-term post-traumatic stress disorders are common. Deaths and serious injuries cause anguish, and bereavement often progresses to depression. 'Survivor guilt' may afflict those who are less affected or unscathed.'

Professor McMichael cites recent studies in Britain that have documented the mental health risks.

In one study, comparing flood-affected and unaffected households, up to three-quarters of those affected by flooding (especially older persons) had a subsequent mental health disorder. In a longer-term follow-up study in southeast England, in the wake of a major river flood, adults had rates of psychological distress four times greater than the general population.

'Similarly, in a large survey of flood-affected persons in 30 locations around England and Wales, their self-reported health-indicator scores revealed considerably higher levels of mental health problems than in the population at large.'