The floods occurred less than 18 months after Australia was affected by the Black Summer bushfires, impacting many towns still recovering from that disaster. They had been preceded by five months of severe weather associated with La Niña, which resulted in minor to major flooding in many parts of northern New South Wales. New South Wales State Emergency Service (NSW SES) had 100 days of operational response activities in the five months before this flood event. The extreme weather conditions delivered incredible amounts of rain in a rapid period over an already well-drenched landscape and catchments, causing evacuations, isolations, and disruption to communities at a time when the state was also being challenged by the COVID-19 pandemic. At one stage, flood warnings covered an area of New South Wales that included a population of six million people. Across the event, over 25,500 residents were subject to evacuation orders.

Weather systems

A major rain event affected significant areas of Australia in the second half of March 2021. The highest rainfall totals occurred in eastern New South Wales, with almost the whole coastline and adjacent ranges receiving significant falls. Extensive heavy rainfall also occurred over large areas of inland New South Wales. In total, 30 of 37 river catchments in New South Wales experienced significant flooding because of this rainfall.

Moist easterly flow became established over coastal New South Wales on 17 March, associated with a strong, slow-moving highpressure system in the southern Tasman Sea. This onshore flow persisted for nearly a week. Troughs formed near the coast from time to time, and a small low-pressure system moved slowly south along the New South Wales coast on 19 and 20 March, reinforcing the easterly flow on its southern side.

Some of the heaviest rain occurred during these two days. The low did not reach the intensity required to be formally classified as an East Coast Low.

Meanwhile, a separate area of low pressure formed over central Australia on 22 March, with a trough and associated north-west cloud band extending from the Kimberley in north-western Australia to the far south-west of Queensland. This consolidated over the following 24 hours into a low-pressure system over inland areas of southern Queensland and northern New South Wales. The low then moved south over inland New South Wales, reaching Bass Strait early on 24 March.

Significant rain began along parts of the New South Wales coast on 17 and 18 March, with heavy falls in the Port Stephens area on 18 March. There was also significant thunderstorm activity in northern inland New South Wales during this period, with locally heavy falls. The heaviest rain began on 19 March, focused on the Mid North Coast, with significant falls covering much of the coast from the Illawarra northwards. Heavy falls extended south to the Sydney region on 21 and 22 March, and northwards to inland NSW and south-east Queensland on 22 and 23 March. The South Coast received regular rain during this period, with its heaviest falls on 24 March as a low approached it from inland. By 25 March rain had largely cleared from New South Wales, except for isolated severe thunderstorm activity on parts of the South Coast that afternoon.

The influx of moisture from a high-pressure system in the Tasman Sea and a low-pressure system in the Timor Sea led to very high daily rainfall totals on several days during the event across south-east Australia. Daily totals exceeded 150 mm somewhere in New South Wales on each day from 18 to 24 March. One of the most significant aspects of this event in coastal NSW was its persistence, which resulted in many very high multi-day rainfall totals. Many locations received several days of heavy rain, particularly on the Mid North Coast, where several sites had four consecutive days with 100 mm or more.

The heaviest rainfalls away from the coast occurred on 23 March, with daily totals exceeding 100 mm in the Northwest Slopes and Upper Western regions of New South Wales. The town of Moree received 150 mm of rain on 23 March – more than it did in the entire severe drought year of 2019 (125.4 mm). Daily totals above 50 mm were widespread through other parts of inland New South Wales.

Several records were broken during this flood event. New South Wales had its second wettest day, third wettest week and second wettest March on record since 1900.

Flooding

The extent of the March flooding in New South Wales was vast and numerous flood records were broken. Several locations saw almost record flood levels (see Table 3). The heavy rain fell against a backdrop of relatively wet antecedent conditions across most of the affected regions, associated with a La Niña which developed in the second half of 2020. Soils became more saturated during 2020, and water storage levels generally increased. This contributed to flooding being more widespread and severe than had been the case during a broadly comparable rain event in February 2020.

In the Northern Rivers area of New South Wales there was minor to major flooding along several river systems. Communities impacted included Grafton, Ulmarra, Maclean, Glenreagh, and Coutts Crossing. NSW SES issued three evacuation orders and a further evacuation warning for communities in the area, affecting approximately 800 people. A total of 16 communities were isolated due to flooding.

Numerous communities in the Mid North Coast were impacted by flooding including Thora, Bellingen, Bowraville, Macksville, Kempsey, Smithtown, Wauchope, Settlement Point, Wingham, Taree, Gloucester, and Laurieton. Numerous evacuation warnings and orders were issued in this area, impacting over 18,000 people. A total of 23 communities and locations were isolated due to flooding, requiring resupply by NSW SES.

Rainfall in the Hunter-Central Coast area resulted in major flooding along the Hunter River at Bulga and moderate flooding at Singleton. Moderate flooding was also experienced in the Tuggerah Lakes area. Communities impacted included Bulga, Wollombi, Singleton and Tuggerah Lakes. Evacuation warnings were issued for areas in Dungog, Singleton and the Upper and Lower Mooney Dams. None of these warnings progressed to evacuation orders. The community of Whittingham, consisting of 16 dwellings, was isolated due to flooding.

Flooding in the Hawkesbury-Nepean Valley and across Sydney impacted numerous communities. The Warragamba Dam spilt, the first significant overflow of the reservoir since 1990, which contributed to the flooding. The Hawkesbury River had multiple flood peaks with waters receding and then rising again in several communities. Communities impacted included Pitt Town, Grono’s Point, Cornwallis, Freemans Reach, North Agnes Banks, Windsor, McGraths Hill, Wilberforce, Colebee Stonecutters Ridge, Marsden Park, Mulgrave, Vineyard, Clarendon, Londonderry, Colo, Wisemans Ferry, parts of Jamisontown, Mulgoa, Penrith, North Richmond, and Eastern Creek. Caravan parks along the Hawkesbury River were also flooded.

Approximately 65,000 people were subject to evacuation warnings and evacuation orders across Sydney, with the majority in the Hawkesbury-Nepean Valley. A total of 35 communities were isolated for varying lengths of time because of the flooding.

Whilst there were no flood warnings provided for the Parramatta River, flash flooding did occur and warnings were issued from the flash flood warning system (Flood Smart) to residents subscribed to this system.

Flooding in the river systems in western parts of NSW was much slower moving. Towns and communities along the Darling, Paroo and Barwon River systems faced flooding and subsequent isolation for approximately six weeks after the rainfall and flooding impacted the eastern coast of NSW. The final flood warnings for these rivers were issued at the end of May 2021.

The township of Moree was severely affected by flooding in western New South Wales. Major flooding impacted low-lying areas of the town, resulting in NSW SES issuing an evacuation order which impacted approximately 4,000 residents. Other areas of the township were isolated during the flooding, with NSW SES assisting residents with resupply.

The response to the severe weather

NSW SES received over 14,557 requests for assistance during this flood event, with over 26,000 calls to 132 500. There were 1,052 flood rescue activations across the impacted communities.

More than 940 flood warnings were issued by NSW SES, approximately half of which were for the northern part of the state.

This flood event saw the largest number of people covered by NSW SES evacuation warnings and orders in any one weather event. A total of 28 evacuation warnings were issued, impacting approximately 62,000 people. There were 24 evacuation orders issued, impacting over 25,500 residents. There were 33 evacuation centres activated across the impacted areas with 2,854 people registering at these evacuation centres.

Over 4,100 members from across NSW SES were deployed in response to the flooding. This included field teams, flood rescue operators, aviation support personnel and Incident Management Team members. Other emergency services from across the state provided support including flood rescue, storm response and incident management teams. These included NSW Police Force, Fire and Rescue NSW, Ambulance NSW, Volunteer Rescue Association, Marine Rescue NSW, and Surf Lifesaving NSW. All functional areas provided support at Incident Control Centres, Emergency Operations Centres, and the State Emergency Operations Centre. Interstate support was also provided by the AFAC National Resource Sharing Centre, with over 350 personnel deployed from across Australia to support NSW SES and the communities of New South Wales. The Australian Defence Force provided aircraft to assist with search and rescue and resupply and was also deployed to assist with relief and recovery efforts in many of the impacted communities.

Aircraft were used to support the response to the flooding with tasks including resupply, reconnaissance, moving personnel into isolated communities and evacuations. Spontaneous volunteers helped their fellow community members filling sandbags to protect properties and assisting with cleaning up flood and storm damage.

There were two flood-related fatalities during this event, both motorists whose cars became submerged in floodwaters.

Impacts on the communities of New South Wales

A total of 15,462 rapid damage assessments were carried out across the impacted areas on a range of buildings. Of these, 10,540 were residential, with 4,375 houses sustaining damage and 1,196 houses found to be uninhabitable.

In Taree, a house was found drifting in the Manning River after heavy rainfall caused by this weather pattern.

There were numerous instances of power outages across the impacted communities. Flights at Port Macquarie were cancelled after the airport was cut off by flooded roads. In the Hunter Valley, flights to and from Newcastle Airport were suspended due to flooding of the airfield.

Roads and other infrastructure were damaged by flooding across the impacted areas. Landslides occurred in some locations resulting in road damage and isolated communities.

A number of educational facilities were closed because of the floods including 376 schools, 244 early childhood centres and 10 TAFE facilities. As at 30 July, all facilities have reopened.

Flood damage to port infrastructure at Port Macquarie prevented the cargo vessel Island Trader, carrying out its usual resupply of Lord Howe Island. Residents faced food and supply shortages over the Easter period. The Royal Australian Airforce provided a C-130J Hercules to fly essential food and gas supplies to the residents and tourists on the island.

Stock and crop losses from the floods have contributed to some shortages and higher costs of food items. The New South Wales Farmer’s Association recognised the impacts the floods would have on farmers and established an appeal through its natural disaster relief fund to assist farmers to continue to operate.

From a health perspective, communities were warned of the environmental health risks associated with the flood clean up with residents urged to treat the floodwater as potentially contaminated with sewage and chemicals, posing a risk of skin and stomach infections. The public was asked to wear protective clothing including face masks and gloves and to boil water before drinking or washing raw food.

From a wildlife perspective, the floods adversely impacted many burrowing animals such as echidnas and wombats which are feared to have been drowned when their burrows were inundated. It will take some time and analysis to understand the full extent of the impact of this event on fauna. During the event wildlife rescuers were active in rescuing kangaroos stuck in drains, animals hit by cars when fleeing to higher ground as well as turtles and seabirds who were swept away from their natural habitat.

Relief and recovery

Natural disaster declarations were made by the New South Wales Government for 78 local government areas impacted by this storm event. This provided affected communities and individuals with a range of special assistance measures including access to financial assistance. The New South Wales Government adopted a policy where recovery work was to be contracted to local small and medium enterprises as a priority to assist the recovery of local communities.

The Australian Defence Force provided a range of support services to the response and relief effort, assisting with damage assessments, helping householders and property owners to commence the recovery effort by cleaning out homes and businesses and moving debris in many locations impacted by the flooding.

The State and Commonwealth Governments have provided disaster relief payments to various groups impacted by the floods including Primary Producer Grants, where there have been 3,575 applications made, of which 2,200 have been approved with $24.5 million disbursed.

Disaster Relief Grants were made to low-income households where the property suffered structural damage and household contents were destroyed by the floods. As at the 30 July, there have been 333 grant applications made and $2,204,635 paid.

A total of $435,388,090 in Australian Government Disaster Payments has been made to individuals impacted by the floods along with $4,441,630 in Australian Government Disaster Allowance payments paid out.

There have been emergency accommodation arrangements for 1,662 affected individuals as of 30 July.

On 22 March, the Insurance Council of Australia declared an insurance catastrophe for large parts of New South Wales following the devastating storms and flooding. As of 30 July, the Insurance Council of Australia reported there had been 53,144 claims lodged with $629.6 million damage incurred associated with this event.