Pluvial period of the 1970s

Over most of the country the 1970s stand in marked contrast to the normal - and generally well deserved - image of Australia as a dry country. Instead, continual rainfall and widespread flooding was the norm, in what was easily the wettest decade of the 20th century.

Though 1970 itself was dry over much of the country, it ended on a wet note in the east, with record or near-record December rains from far southern Tasmania to Roma in Queensland. Wet, stormy conditions continued in the east in early 1971 - a La Niña year. In January flash flooding in Canberra’s Woden Valley took seven lives, and serious flooding also affected Victoria’s Gippsland District. Heavy rains fell across inland areas in March and April; and in June, cloudbands extending from the tropics dumped 150-200mm over normally arid parts of northwest Australia: nearly a year’s rainfall in a month. The 1971-72 Wet set in early over northern Australia, and record or near-record November rains affected large areas; in Melbourne, an intense depression early in the month generated the worst flooding since 1934.

A “heavy track” at Flemington Racecourse, Melbourne, a few days after the 1971 Melbourne Cup, following the worst flooding in many years. This scene was typical of large areas of Australia during the early to mid-1970s (photo courtesy of The Herald and Weekly TimesPhotographic Collection).

After a wet summer in southeastern Australia and eastern Queensland, a strong El Niño developed in March 1972, bringing an 11-month drought to much of the country. This drought broke emphatically in February 1973, with exceptional rainfall over South Australia and the eastern states. As El Niño rebounded into La Niña, well above average rains soaked large areas month after month. By late winter many a football match in southeastern Australia was played on ovals resembling lakes!

La Niña dominated the period 1973-75, and the unusual rains continued. The events of January 1974 are described in the article entitled 'The Big Wet, January 1974', under the flood menu item. In April and May 1974 downpours in South Australia, Victoria, Tasmania and western New South Wales generated widespread flooding. July was wet over southern Australia, and above-average rains were widespread for the next three months. Lake Eyre filled in early 1974 for the first time since 1950 (and for only the second time in the century) and, fed by continuing heavy falls until March 1976, retained water into 1977.

The first half of 1975 was drier - especially over the southeast - but heavy rains returned after July, with widespread flooding over many parts of the country in October. Heavy falls continued in early 1976 over Central Australia and inland parts of Queensland and western NSW. Crops prospered as never before: From 1973 to 1976, the national wheat yield exceeded 1.32 tonnes/hectare each year, the highest recorded to that time.

From autumn 1976 rainfall declined over most of the country apart from the Northern Territory and Queensland. Below normal totals were more general in 1977. The breakdown of El Niño early in 1978 triggered another wet period over most of the country: in many cases rain between May and October exceeded that of comparable periods in the wet early 1970s. South Australia had another wet year in 1979, but elsewhere the “pluvial” essentially ended in 1978.