Floods in New South Wales facts for kids

Australian rivers have faced many big floods, especially in New South Wales. We have records of these floods going all the way back to when Australia was first settled. Most floods in New South Wales happen because too much water flows into the rivers there. Sometimes, floods also come from rivers in Queensland and Victoria. Floods can cause huge problems for towns and cities, and they can really hurt the local economy.

The main natural feature in New South Wales is the Great Dividing Range. This is a series of low mountains and plateaus that run from north to south, close to the coast. Flooding happens on both sides of these mountains. However, floods are usually worse and happen more often on the eastern side, closer to the coast. This is because more water flows there, and many more people live in those areas. The main weather event that causes these floods is called an Australian east coast low.

Australia had some very big floods in 2010 and 2011. There were floods in Queensland and Victoria in March 2010. Then, more floods hit Victoria in September, and Queensland from December 2010 to February 2011. Finally, Wollongong in New South Wales also experienced floods in March 2011. Even though some of these floods were in other states, the ones in Victoria and Queensland were considered some of the worst Australia and New South Wales had ever seen.

Major Flood Events in New South Wales

Gundagai: A Town and Its Floods

Gundagai is a small country town. It sits right on the banks of the Murrumbidgee River in the South West Slopes area. This town has been hit by many floods over the years, especially in the 1800s. The Murrumbidgee River has risen more than 7 metres (23 ft) at Gundagai nine times between 1852 and 2010. This means it flooded about once every eleven years. Since 1925, most floods have been small. But in 1974 and December 2010, the river rose very high, reaching 10.2 metres (33 ft) in 2010.

The Gundagai floods on June 25, 1852, were some of the worst in Australian history. The town was completely cut off and soaking wet after almost three weeks of heavy rain. It's thought that at least 89 people died in these floods. This is the highest number of deaths from flooding ever recorded in Australia. At that time, only about 250 people lived in Gundagai. This means more than a third of the town's population was lost. After the 1852 floods, the town was rebuilt on higher ground to be safer.

In 1925, four people died when the Murrumbidgee River flooded Gundagai. The flood lasted for eight days. Another major flood happened in March 2012 along the Murrumbidgee River. This flood also affected Wagga Wagga, which is downstream from Gundagai. The river peaked at 10.56 metres (34.6 ft) in Wagga Wagga on March 6, 2012. This was just a little bit lower than the 1974 flood level of 10.74 metres (35.2 ft).

Hunter Valley: The Big Flood of 1955

Heavy rain had been falling across eastern Australia since October 1954. Then, on February 23, 1955, a strong monsoon storm moved south from Queensland. Extremely heavy rain began to fall, especially in parts of New South Wales from Warren to Cassilis. Some areas received more than 250 millimetres (9.8 in) of rain in just 24 hours. This is a huge amount for that region. The heavy rains then moved east over the Liverpool Range and into the Hunter Valley. Because the ground was already very wet, the Hunter River and other rivers quickly reached record-high levels.

The Hunter Valley flood on February 23, 1955, caused 24 deaths. Most of these deaths happened in Singleton and Maitland. Five people died from electrocution while trying to rescue others. A total of 7,000 buildings and homes were damaged. The total cost of the flood was about A$1.3 billion dollars. Cleaning up after the flood took many months, but eventually, homes were fixed and businesses reopened.

Murray River: The Long Flood of 1956

No one died in the 1956 flood of the Murray River. However, it was still a very important flood because it lasted for a very long time – over seven months! It also had a big impact on the Far West Region of New South Wales. It also affected parts of Victoria and South Australia that are west of Wentworth. This is where the Murray River meets the Darling River. Because of this long flood, the Menindee Lakes were built. These lakes help control floods on the Darling River.

Hawkesbury and Georges River: Sydney's Wettest Day in 1986

In 1986, six people died, and 10,000 homes were damaged in floods affecting the Hawkesbury and Georges Rivers. The damage was estimated to be around $35 million. On this day, Sydney received 327.6 millimetres (12.90 in) of rain in just 24 hours, making it Sydney's wettest day ever recorded. The heavy rain caused a lot of problems. Roads were flooded, and many drivers had to leave their cars. Bus services were severely disrupted in the city, and trains stopped running because tunnels were flooded.

Hunter Valley and Central Coast: The 2007 Storm

A very strong storm system, called an east coast low, formed on June 8, 2007. For the next 36 hours, the Hunter Valley and Central Coast were hit by powerful winds and extremely heavy rain. This caused widespread flooding, damage, and sadly, loss of life. A large ship, 225-metre-long (738 ft), was even washed ashore. The strongest wind gusts recorded were 135 kilometres per hour (84 mph) at Norah Head and 124 kilometres per hour (77 mph) at Newcastle.

A family of four and their nephew died when a section of road collapsed under their car on the Pacific Highway at Somersby. Two people drowned when their four-wheel drive car was swept off a bridge by floodwaters at Clarence Town. Another man died near Lambton when he was swept into a storm-water drain. The next day, a man died when a tree fell onto his car at Brunkerville. Another man died in a house fire, which was thought to have started from a candle used during power outages caused by the storm. In total, ten people died.

On June 10, about 4,000 people living near the river in central Maitland, South Maitland, and Lorn were told to leave their homes. This was because people expected the Hunter River to break through its flood walls. Evacuation centers were set up at East Maitland and Maitland High School. However, by the morning of June 11, the floodwaters had reached their highest point without breaking the flood walls.

Wollongong: The 2011 Downpour

The March 2011 flood in Wollongong and the Illawarra region happened because of a large storm. This storm covered most of the southern parts of the state and brought very heavy rain to suburban Sydney and nearby areas. The Bureau of Meteorology warned about flash floods for the South Coast, Riverina, Illawarra, South West Slopes, Snowy Mountains, and Southern Tablelands. They expected the heavy rain to continue. In the first 48 hours of the flood (March 20–21), 160 millimetres (6.3 in) of rain fell in Wollongong. Robertson, in the Southern Highlands, recorded the state's highest rainfall on March 21 with 83 millimetres (3.3 in). This amount equaled the March record from 2003. Sadly, a man was believed to have drowned after his body was found at a stormwater bridge at Warilla.

Northern New South Wales: Floods in 2012

Heavy rain started falling in Queensland in early 2012. It then moved south, causing floods in central and western Victoria, New South Wales, and Tasmania. The flooding event in March 2012 meant that 75 percent of New South Wales was under flood warnings. This forced many people to leave their homes, and the government declared these areas natural disaster zones. It was estimated that 16,500 people across New South Wales were cut off by the floods. With so many parts of New South Wales still underwater, it was hard to know how much damage had been done to public and private buildings and roads. The cost could have been as high as A$1 billion dollars.

Northern New South Wales: Cyclone Oswald in 2013

On January 17, Tropical Cyclone Oswald formed in the Gulf of Carpentaria. This cyclone then caused 11 days of very heavy rain off the Queensland coast in the Wide Bay–Burnett area. Major flood warnings were issued for many rivers in New South Wales. These included the Bellinger, Kallang, Macleay, Manning, Nambucca, and Tweed Rivers. Warnings were also issued for Camden Haven, the Clarence Valley (including the Orara River), and Hastings. Severe weather warnings were also in place for much of the state, meaning there was a threat of heavy rains, very strong winds, and dangerous seas.

About 41,000 people in New South Wales were temporarily cut off by the flooding. In the Tweed Valley, the Tweed River reached 3.3 metres (11 ft) on January 28. This was the highest level recorded in 30 years. In Grafton, the Clarence River reached a new record height of 8.1 metres (27 ft). Records for the river height in Grafton go back to 1839. The city's flood wall helped prevent more serious flooding. Even so, about 1,500 people living near the Clarence River were asked to leave their homes on the night of January 28. Maclean was saved from flooding by its own flood wall. The Clarence Valley was not as lucky, with many properties cut off and without power. The area was officially declared a disaster zone, as was the Tweed Shire. Some minor flooding and road closures also happened in the Hunter Valley.

Northern NSW: After Cyclone Debbie in 2017

After Cyclone Debbie hit in March 2017, Northern New South Wales was again badly affected by floods. Lismore was the worst hit, with floodwaters reaching up to 3.5 metres (11 ft) through all businesses in the city center. The Wilsons River reached 11.6 metres (38 ft), and the flood wall, which was finished in 2005, was completely covered by water.

Central West and Riverina: The 2016 Floods

The Bureau of Meteorology announced that 2016 had the third-wettest winter on record. Unusual heavy rainfall across most of the state, especially in the area where the upper Lachlan River starts, happened during autumn and winter 2016. This caused Wyangala Dam to fill up from 38 percent to 90 percent of its capacity. By early August, the Bureau of Meteorology had issued flood warnings for the Orara, Macquarie, Bogan, and Lachlan rivers. In late August, Water NSW started releasing up to 10,000 megalitres (350×10^⁶ cu ft) of water per day from Wyangala Dam. This was done because more rain, between 20 to 40 millimetres (0.79 to 1.57 in) daily, was expected in the dam's area.

Moderate to major flooding first hit Forbes and Condobolin in early September. By mid-September, experts predicted widespread flooding across most of inland New South Wales. By late September, flooding in Forbes reached its highest point at 10.67 metres (35.0 ft). About 1,000 people had to leave their homes, and the Newell Highway was cut off both north and south of Forbes' main business area. The State Emergency Service and the Australian Defence Force provided help. As the Lachlan River flowed into the Murrumbidgee, major flooding happened downstream in late October and early November. This affected Hay, Darlington Point, Carrathool and Hillston. Sadly, the body of a man from Burcher was found, and it was believed he had drowned.

• December 2020 NSW North Coast Floodings