Floods and storms

Floods and extreme storms damage property and infrastructure and affect the health and wellbeing of NSW communities. Flooding in urban and rural NSW costs our economy about $250 million each year, and causes loss of life and emotional distress. The frequency and intensity of floods and storms are likely to be affected by climate change. Research to better understand such changes is underway.

Research update

OEH is collaborating with several government agencies and research institutions to provide updated information on the potential impacts of climate change on floods and storms.

The NARCliM climate projections allow future changes in rainfall to be studied at time periods ranging from hours to years and at a resolution of 10km for the whole of south-east Australia. Future changes in annual and seasonal average rainfall were previously assessed based on the NARCliM climate projections, and are documented for each State Planning Region of NSW and ACT.

In new research, the NARCliM climate projections were used to study the implications of climate change for future rainfall extremes and east coast low storm events.

Rainfall Extremes

Extreme rainfall events are often associated with large damaging storms. They can cause riverine and flash flooding, soil erosion and impacts on water quality.

In recent research, NARCliM climate projections were used to assess the potential for the frequency and intensity of extreme rainfall events to increase in the future.  Rainfall extreme indices, or ETCCDI (Expert Team on Climate Change Detection and Indices (http://etccdi.pacificclimate.org), were examined for any significant changes. The main findings are:

  • Rainfall extremes are projected to increase in the near future (2030) and far future (2070).
  • The increases in the near future are not considered to be significant - the changes fall within the range of inter-annual rainfall variability recorded in the past.
  • In the far future, significant increases in several rainfall extreme indices are projected for some regions of NSW.
  • The state planning regions with the most frequent significant increases in extreme rainfall indices in the far future are the Far West, Murray Murrumbidgee, and New England and North West. Some significant increases were also found in the Hunter and South East and Tablelands regions.
  • The Simple Precipitation Intensity Index (SDII) is the only index to have significant increases over large parts of NSW. This suggests that the mean rainfall intensity will increase even though the more extreme indices do not show significant changes.
  • Over most of NSW, little change is projected in the maximum wet spell. A small but not significant increase projected in the maximum dry spell is a reverse of the decreasing trend apparent in past rainfall records.

Download information

Biodiversity Technical Report
Rainfall Extremes

ASHX - 7.6 mb

Additional information

East Coast Lows

Storms and floods in NSW are often associated with east coast lows. The Eastern Seaboard Climate Change Initiative – East Coast Lows (ESCCI-ECL) program is a research cooperative led by OEH. This research is giving us a much better understanding of future possible changes in the frequency and intensity of east coast lows and their associated impact on the NSW coast.

See East Coast Lows for more information on the ECL research outputs.

OEH management of flood risk

Managing flooding is an important priority for the State Government and local councils in NSW. All local government areas in the state are exposed to some degree of flood threat, whether from rivers or local overland flows. The damage caused by flooding can be significant.

Hazard Profiles 2010

In 2010 The Impacts of Climate Change on Natural Hazards Profiles were developed by OEH in collaboration with the Bureau of Meteorology, the Ministry for Police and Emergency Services, and the University of Wollongong under the auspices of the NSW State Emergency Management Committee. Hazard profiles were developed for each state planning region.

Read the overview of likely changes to natural hazards in NSW Statewide Overview (PDF 227 KB)