General Comments on Flooding

• The most flood prone areas of South Australia are the trench of the River Murray, the low-lying areas of the Adelaide plains and, to some extent, the northern outback areas. Because the first two areas are the most populous in the State it is those that are at risk of the greatest personal, social and property loss.
• Flooding is not a regular hazard to life and property in South Australia although the State is not totally free from risk and incident. One recent and exceptional periodic flood was caused by thunderstorm rains on 2 and 3 March 1983 causing about $65 million (2002 valuation) damage to Adelaide and suburbs, the Barossa Valley and areas was to menace the most settled areas of the State.
• The heaviest rainfall recorded (Adelaide Rainfall Station) within a 24 hour period in the metropolitan area of Adelaide was recorded on 6 February 1925 when 141.5 mm of rain fell. Severe general local flooding followed. Stormwater caused street and park flooding in areas immediately west of the city and North Adelaide. Many houses and business premises were flooded. The Mile End goods yards were severely flooded, disrupting rail traffic.

The River Murray Floods of 1956

• The most destructive River Murray floods were experienced in 1956. The peak of this flood reached Renmark on 24 August and passed downstream during the following two weeks. This flood was caused by the unusual coincidence of high rainfall in the River Darling catchment in Queensland and abnormal autumn rainfall in the River Murray catchments in New South Wales and Victoria. The flood volume in South Australia was nearly five times the normal river flow causing about $310 million (2002 values) damage to farms, orchards, vineyards, roads, public infrastructure and houses. It has been estimated that the annual exceedance probability of this flood was a 1 in 140 years. Flooding lasted from May 1956 to January 1957. Peak flow was 341,300 megalitres (341,300,000 tonnes) per day (13-17 August 1956). This was sufficient to fill Adelaide's Mount Bold reservoir seven times each day. Total flow to South Australia for 1956-57 was 48,225,000 megalitres (48,225,000,000 tonnes), enough to supply Adelaide for 250 years at the rate of consumption in 1956.
• Fortunately for South Australia, monitoring of rainfall and river levels in the Eastern States gives ample warning of a River Murray flood.
• Although some hydrological records of flood events and river flows have been kept since early in the 1900s, full, accurate and consolidated records for most river systems have only been introduced in the past 30 years.

Flood Control

• Not all flooding is damaging. Some localities in South Australia actually look forward to regular floods. Langhorne Creek in the Bremer Catchment features a wine-making community in this area and river flooding produces bigger and better grape harvests.
• In South Australia steps have been taken to mitigate the effects of flooding in local areas and broader catchments.

Flood Mitigation Programs

• The introduction of dams, locks and barrages into the Murray Darling basin following the River Murray Waters Agreement in 1914.
• The construction of the Torrens Outlet in the mid 30s.
• The building of Kangaroo Creek Reservoir.
• The upgrading of the Torrens linear park.
• The South East drainage scheme.