Rainfall across the majority of the Adelaide region was above average for the 2010–11 year (Figure C1). Rainfall in the northern parts of the region was very much above average. The total area-averaged rainfall over the Adelaide region during 2010–11 was 778 mm, which is above the mean annual average rainfall of 635 mm. The observed above average rainfall led to increased runoff and resulted in increased inflows to storages (see the Surface water section in the Resources and systems notes).
Figure C1. Map of annual rainfall deciles for the Adelaide region during the 2010–11 year
Rainfall across the region ranged from more than 1000 mm in the Adelaide Hills to less than 600 mm in coastal areas west of the city of Adelaide (Figure C2).
Figure C2. Map of total annual rainfall for the Adelaide region during the 2010–11 year
The main driver of rainfall across eastern Australia between September 2010 and March 2011 was a very strong La Niña event in the Pacific Ocean. As a result, wet conditions were experienced across much of South Australia, including the Adelaide region.
In the Adelaide region, August and September were the wettest months of the reporting period (Figure C3). Some stations in the Adelaide region recorded their wettest August on record. An intense low pressure system, which developed in early September, broke daily rainfall records for the month at more than ten stations across the Adelaide region. December 2010 and March 2011 were both the second wettest on record in the Adelaide region for their respective months. The area-averaged rainfall for both months was more than three times the long-term average.
The La Niña event concluded in April 2011 and below average rainfall conditions prevailed across the Adelaide region for the final months of the 2010–11 year (April to June 2011).
Figure C3. Graph of total monthly rainfall for the Adelaide region during the 2010–11 year compared with the long-term average and percentiles for the region
Evapotranspiration across the Adelaide region was average to above average for the 2010–11 year (Figure C4).
Figure C4. Map of annual evapotranspiration deciles for the Adelaide region during the 2010–11 year
The total area-averaged evapotranspiration over the Adelaide region during the 2010–11 year was 664 mm. Evapotranspiration was highest in the western area of the region including the Mount Lofty Ranges and the Fleurieu Peninsula (Figure C5). Evaporation decreased moving further east, and was lowest across the Adelaide Plains and at the coast.
Figure C5. Map of total annual evapotranspiration for the Adelaide region during the 2010–11 year
The Adelaide region experienced mean daytime temperatures below the long-term average during the 2010–11 year (Figure C6).
Figure C6. Map of annual maximum daily temperature deciles for the Adelaide region during the 2010–11 year
Mean maximum daily temperatures varied by 4 °C across the region, with values ranging from more than 22 °C in the northwest (west of Gawler) to less than 18 °C in the Mount Lofty Ranges, along the eastern border of the region, and the southern coastal area (Figure C7).
Figure C7. Map of annual maximum daily temperature deciles for the Adelaide region during the 2010–11 year
La Niña events are typically associated with cooler-than-average daytime temperatures, particularly in eastern parts of Australia from October to April. Except for January, monthly mean daytime temperatures for the Adelaide region were near or below average between August and May (Figure C8).
Figure C8. Graph of average monthly maximum daily temperature for the Adelaide region during the 2010–11 year compared with the long-term average and percentiles for the region