The bar chart below compares the water levels in the reservoirs of six Australian cities in October in two different years : 2009 and 2010.
Overall, all countries in question adhered to rising trends, with the exception of Perth and Sydney, which saw a decrease or no change at all. Notably, Brisbane maintained a position of unbroken superiority in water levels, while Melbourne and Perth registered, generally, the lowest rates. The most pronounced water level rise was observed in Brisbane, whereas Perth showed a starkly contrasting pattern, recording the most noticeable water level drop.
Brisbane stood out by accounting for the highest shares in the whole dataset, having recorded 75%, the same as Darwin, in its initial year. Following 2009, both cities saw their figures grow, albeit to varying extents; while water levels in Brisbane rose to an all-time chart high of 100% (maximum), those in Darwin saw a marginal uptick by 5 percentage points. Following closely behind are reservoirs in Canberra and Melbourne, which also saw increments in their water levels, with the former city recording the second most pronounced growth, from 50% to 73% , and the latter city creeping up slowly from 35% to a high of 45%.
Sydney and Perth, on the other hand, bucked the foregoing trend; while reservoirs in Sydney experienced neither rise nor fall in water levels, those in Perth succumbed to a significant drop, falling from just above 50% to an all-time low of 26% – the lowest figure in the dataset.