The impacts of flooding include the obvious visible damage to housing and businesses, but they also affect people in terms of health. Health impacts can include physical injuries, lack of access to healthcare and medication, and mental health problems such as post-traumatic stress, anxiety and depression.

Our research on the mental health and wellbeing of the community following devastating flooding in northern NSW in 2017 showed that:

• The mental health and wellbeing impacts of flooding affected people who were directly impacted by the flood (by having flood water in their home for example), as well as people who were indirectly affected (by having disrupted access to health and social care for example)
• The mental health and wellbeing impacts of the flood were long-lived
• People who were disadvantaged were more likely to be evacuated, displaced and suffered worse mental health and wellbeing outcomes than people who were not disadvantaged
• People with stronger feelings of belonging and informal social connectedness had better mental health than those with less belonging or informal social connectedness.

In terms of mental health and wellbeing, to help people to stay safe, services/providers can:

• Provide support for those indirectly as well as directly impacted
• Provide support over the longer term
• Look out for disadvantaged people impacted by the flood
• Provide opportunities for social networking

Driving through floodwater and playing/recreating in floodwater are the two behaviours most associated with deaths in floods in Australia. In our national survey (2019/20), 55 per cent of the public reported that they had driven through floodwater in the last five years. This behaviour is often normalised, with those who do it being likely to do it more than once/repeatedly.

Most people claim to have driven through floodwater after ‘careful consideration’ rather than it being a spur of the moment thing, also social pressure to keep going and not turn around comes into play.

Based on research, it is likely that the majority of people will comply with requests to not drive through floodwater whilst water levels are rising and flooding is in progress. However, once the rain stops and/or water starts to recede, this is when people are likely to take risks. They are keen to ‘get on with things’ and ‘press on’– whether that’s clearing up or checking on things, or just getting back to normal. This is often when accidents happen.

Frequencies of La Ninas and El Ninos has been impacted by climate change, plus the intensity of extreme precipitation has increased significantly. We could be seeing flooding perhaps because we’re entering a back to back La Nina year where antecedent conditions are already wet, increasing the magnitude of the flood peak considerably.

Policy makers must not lose sight of what is important here – climate change impacts both flood and drought extremes, and both anomalies can be managed as they have been for so many years – all we need is the will of taking actions with clarity and conviction.

Major flooding is occurring along the Lachlan River. This will no doubt give voice to those in favour of the $2 billion+ NSW Government proposal to raise Wyangala Dam on the upper Lachlan River near Cowra to increase its water storage capacity by 50%. However, this flood is not particularly unusual or high, rather the flood risk has been poorly managed by the NSW Government.

 This flooding is awful news for the people whose homes, farms and other businesses will be badly impacted. However, raising the dam is the wrong way to manage flood risk along the Lachlan River for three reasons:

1. Flood ‘control’ infrastructure usually makes flood damage worse, not better;
2. There are cheaper, more effective flood management alternatives; and
3. The high water levels generate a lot of socio-economic and environmental benefits that would be lost if medium sized floods are captured by a higher dam.

In more detail:  

Flood ‘control’ infrastructure makes flood damage worse

Raising the dam will inevitably make flooding impacts worse. Globally this phenomenon is known as the “levee paradox”. This is where flood control infrastructure results in development on the floodplain that makes damage worse when inevitably there is a big flood that is not contained by infrastructure. An egregious Australian example is that the flood control capacity built into the Wivenhoe Dam in Queensland after the 1974 floods was insufficient to prevent extensive damage in the 2011 Brisbane floods because too much development was permitted in the floodplain. In general, learning to live with floods is safer than fighting floods and failing.

Better alternatives

Any flood impacts are due to years of NSW Government neglect in not implementing their own three Floodplain Management Plans along the Lachlan, which have particularly recommended actions to enable low level flood waters to pass safely by and not build up behind floodplain infrastructure (like road, railway and irrigation canal embankments). Despite anecdotal claims of flooding in the valley being a major problem, the few recent publicly available assessments (e.g. on NSW SES website) of flooding in the valley demonstrate only modest impacts that could be significantly reduced at little cost if the NSW and local governments thoroughly implemented their findings.
Two egregious examples of NSW Government agencies failing to take sensible flood risk reduction activities stand out:

1. The NSW Government’s Lachlan River Gooloogong to Jemalong Gap Floodplain Management Plan (2011) says that “A major restriction to flood flows is the Forbes/Stockinbingal Railway. Inexplicably, the NSW Government has not asked the Inland Rail Track Corporation as (re-) construction of the railway line commences to rebuild this section with more culverts for the safe passage of flood water.
2. Past floods cutting the Newall Highway have been anecdotally cited as a major socio-economic impact. However, Transport for NSW’s Newell Highway Corridor Strategy (2015) does not prioritise the Lachlan floodplain crossing for action to reduce impacts, e.g. raising the carriageway.

These sorts of flood risk reduction interventions would be much cheaper and faster than raising the dam.

Benefits from floods need to be maintained

High water levels in the Lachlan River, which have some negative impacts, are also a boon to the region’s environment, communities and industries. The Lachlan Valley has 470,000 hectares of nationally significant wetlands that depend on beneficial flooding to remain healthy, such as the Great Cumbung swamp. These wetlands ecosystems are vital for supporting fish and waterbird populations. Fishing is one of the major recreational activities that supports tourism in the Lachlan Valley. The inundation of the floodplain is especially beneficial for pastoralists along the river, and can significantly enhance livestock turnoff. Crucially in a dry region, the inundation of the floodplain is vital for recharging aquifers that supply farms and towns with high quality water. Indigenous nation’s cultural and economic values depend in large part on the environmental benefits of wetland inundation.
 
Raising Wyangala Dam would jeopardise these benefits for people and the environment. The proposal to raise Wyangala Dam is a knee-jerk, pork barrelling proposal that will fail any independent cost-benefit analysis. Ecosystem based climate change adaptations, such as giving rivers room to flood safely, will provide more benefits to society."

Forbes has a long history of flooding, which has commonly occurred during Spring. The highest flood recorded occurred in June 1952 peaking at 10.8 metres. Current predictions are for the river height at Forbes to peak near 10.65 metres. After peaking at Forbes, flooding will move downstream over the coming days potentially isolating small rural communities for several weeks. During the 2016 flood, the Newell Highway was closed for several weeks significantly disrupting freight transport.

Forbes typically receives several days of warning allowing damages to be minimised and evacuations conducted. The greatest concern is people driving through floodwater. In an observational study 84 per cent of motorists chose to ignore road closure signs and drove through floodwater. Between 1960 and 2015, 49 per cent of Australia’s 546 flood fatalities resulted from people driving into floodwater totalling some 229 vehicle-related fatalities.
 
There is a strong likelihood that further storms and floods will impact communities over the coming months and now is the time to make sure homes and businesses are prepared.

Backed by the latest research, there has been a transformation in recent years in the role of the community working with the emergency services in preparing for flood. We know from this research that if you live in an at risk area, the best thing you can do to keep your family safe is to enact your plan and stay informed on the latest warnings – which is exactly what the New South Wales SES is asking residents to do. Do not wait and see what may happen, as by then it will be too late, and you will be risking the safety of yourself and of the emergency services.

With climate projections showing that extreme weather is becoming more likely, research has a key role to play in protecting our homes, businesses and roads. Science has already taught us so much, but there is more to learn, particularly around what and who is at risk as communities undergo change, along with the climate. This is why we need new knowledge and research to help inform decision makers and communities.

We cannot say that this particular event is related to climate change, but we know that with greenhouse warming there is an increased chance for more extreme events to happen in many regions.

There are a combination of factors that are conducive to intense rain in the region.
 
Since this winter, the Indian Ocean temperatures have been in a negative phase of the Indian Ocean Dipole (IOD), which was responsible for the record breaking rains in September 2016. A negative IOD means that ocean temperatures in the east Indian Ocean, close to Australia, are warmer than normal, while ocean temperatures are cooler in the west, closer to Africa. This pattern tends to enhance rainfall for the southern and south-eastern parts of Australia, but the negative IOD has weakened in the past two weeks.

There is a high chance for a La Nina to develop because temperatures in the Pacific are cooler than normal. As a result, warm water is closer to Australia in the western Pacific and this can increase the chances of extreme rain and floods.

Another contributor is the Southern Annular Mode (SAM) which has been in its positive phase since mid-October and that is generally associated with increased rainfall in east and southeast Australia during spring and summer.