Moruya Heads is a small coastal village (pop. 800) located on the south coast of New South Wales.
The first official records of rainfall in Moruya Heads were in June 1875. Since then, rainfall data has been recorded continuously since then and still continues in 2011. This data set is remarkable in that there are no missing records since June 1875. This has resulted in a record of 135 years of annual rainfalls at Moruya Heads, 1876-2010.
The graph of the annual rainfalls at Moruya Heads shows that the rainfall has varied in cyclical patterns (generally every 10-15 years) over the past 135 years without any long-term trends to either increase or decrease. The 43-year period between 1950 and 1992 was a period with many wetter years (twelve years over 1400 mm, compared with only two years in the other 92 years). It would appear that since 1993 Moruya Heads has returned to its pre-1950 rainfall pattern.
The overall average annual rainfall was 954 mm, but this has varied between 468 mm (in 1982) to 1822 mm (in 1934). The 2010 total was 1051 mm - only slightly above average but still (just) the wettest year in the 18 years since 1992.
The main feature of the recent drought (since 1993) was its duration. In the past there have been droughts of similar intensity but shorter duration - such as 1901-1910 and 1935-1948.
It is notable that there is no trend of “dry” years becoming “drier”, with seven years having annual rainfalls between 350 and 450 mm.
Other stations on the south coast of NSW with long periods of rainfall data include Narooma, Bega and Candelo. All of these stations show very similar annual rainfall patterns to Moruya Heads.
The monthly rainfall data used for the above analysis can be downloaded from the Bureau of Meteorology website: http://www.bom.gov.au/climate/data/index.shtml
LINKS TO OTHER RAINFALL ANALYSES
This article was written by Brian Gunter of Narooma, NSW. In his previous life Brian was an engineering hydrologist involved over many years in the analysis of rainfall and river flow data for the planning of water resources projects in Australia, Asia and Africa. In recent years he has been one of the volunteer weather observers of Marine Rescue NSW (formerly Royal Volunteer Coastal Patrol) who operate the Narooma station for the Bureau of Meteorology.
Prepared: 25 January 2011