Yarra River
The river that sculpted a city
Yarra River at Warburton
By world standards, the Yarra River - the major natural feature on Melbourne's landscape - is not in the big league.
It runs for just 242 kilometres, from its source on the flanks of Mt Baw Baw to the head of Port Phillip Bay.
It is neither very long, very wide, nor very deep.
It is not even very clear.
The Yarra has been dubbed "the river that runs upside down", a jibe at its "high turbidity", which means from the middle reaches, the Yarra carries a lot of suspended silt downstream.
But this visually humble, sepia-coloured river has a very strong character and has had a disproportionate impact on shaping and serving the state capital that grew up on its banks.
Moody waters
With 24 tributaries, and draining a catchment of 4060 square kilometres - including about half the area of metropolitan Melbourne - the Yarra was historically a watercourse of such unpredictable seasonal mood swings that building anywhere within the flood plain was risking buildings, fences, crops and farm animals washing away in floods that occurred almost annually.
Flooding in Healesville
Victorian State Rivers and Water Supply Commission, photograph, 1934
La Trobe Picture Collection
State Library of Victoria
The first white explorers noted evidence of floodwaters rising 20 metres or more. And in the century between the founding of Melbourne in 1835 and the devastating spring flood of 1934 - which left 18 people dead, 6000 homeless and spread as a single lake from South Yarra to Warrandyte - it was the river that determined how the city developed.
Unusually, the biggest flood plain is a long way from the river's mouth. The 40 kilometre long flood plain, that stretches from Yarra Junction to Yering Gorge, endowed the world-famous Yarra Valley wine growing region with its wonderfully productive soils.
High ground
The 40 metre deep lava flow that a million years ago forced the Yarra into a narrow gorge near Alphington - and that marks the easterly edge of one of the largest volcanic plains on earth - caused floodwaters to back up so often and so extensively that it led to the creation of Australia's largest urban parkland.
The picturesque, 25 kilometre long Yarra Valley Metropolitan Park has a secondary function as a flood holding basin.
Melbourne's Upper Yarra Reservoir supplies much of the city's water supply
The river's ancient delta that was defined by the sandy, swampy reaches stretching between St Kilda and Williamstown meant that the city of Melbourne was initially established on the higher northern bank. The low, flat land on the southern bank was largely left to light industrial development until late in the 20th century.
Albert Park Lake is the last remnant of those delta swamps and today is an important urban parkland and scene of the annual Australian Grand Prix.
The lower Yarra was modified early this century to cope with larger flows so that the frequent floods that once affected the low-lying parts of the city are now a thing of the past.
Everywhere you look along the river valley there is evidence of how the Yarra helped to shape the city of Melbourne.