Before and after aerial imagery reveals early impact of Victorian floods

By Rachael Dexter and Ben Grubb

The areas around Shepparton, Rochester and Maribyrnong have been the focus of much of the devastation in Victoria over the past few days as a result of widespread flooding.

Echuca, Murchison, Carisbrook, Kerang, Horsham, Newbridge and other towns have also been impacted or are expected to be.

Using Nearmap’s aerial camera system attached to planes, as well as satellite imagery, The Age and The Sydney Morning Herald can provide a bird’s-eye view of the spread of the inundation by comparing the regions before and after the floods. The satellite imagery comes via Sentinel-2 – a constellation of two polar-orbiting satellites placed in the same sun-synchronous orbit by Europe’s Earth Observation Programme in 2015.

The images show how the weather event caused the Goulburn, Murray, Maribyrnong, Campaspe and Avoca rivers to burst their banks. In Melbourne’s Port Phillip Bay, murky floodwater can be seen draining into the ocean from the Yarra River.

Aerial images aren’t available for all regions, either because of cloud cover obstructing the view or because satellites or planes have not yet passed over those regions. The brightness and contrast of some of the satellite images have been increased to improve visibility.

With flood warnings still in place for parts of the state, the situations captured in these images are likely to change again in the near future.

Shepparton and surrounds

In Shepparton, the impact of the flooding of the Goulburn River on the township is evident from satellite imagery taken on Monday. Brown river water can be seen in streets located three kilometres from the river.

As many as 7300 properties in Mooroopna, Shepparton and Kialla West could be impacted, according to the SES. The Goulburn had receded to 11.74 m by 2pm on Tuesday after it peaked at 12.06 metres on Sunday night.

Parts of Shepparton were still subject to “too late to leave” emergency advice on Tuesday afternoon.

Melbourne’s suburbs and Maribyrnong

The above satellite imagery of Melbourne was captured about 11.30am on Monday – after the Yarra and Maribyrnong rivers had peaked over the weekend. The image shows the sediment and mud that has been washed into Port Phillip Bay.

More than 240 homes were flooded in Maribyrnong, in Melbourne’s north-west, on Friday when the Maribyrnong River, which runs north to south through the centre of the image, breached its banks. The river peaked at 4.22 metres on Friday.

Notably, the Flemington Racecourse – which has been criticised over a flood wall installed in 2007 – can be seen in pristine condition in the image above.

Charlton

Residents of Charlton had a lucky escape when the Avoca River peaked at 7.87 metres at 1.40am on Monday, avoiding the total inundation experienced in 2011 when 400 homes were affected.

The emergency warning for the area has been downgraded to a watch and act advice message.

As of 2pm Tuesday, the river was at 5.42 metres and falling. But there was now a major flood warning for residents on the river downstream of Charlton.

Murchison and surrounds

The tiny town of Murchison, 40 kilometres south-west of Shepparton, has seen farmland inundated outside the normal area of river swelling, as seen in the satellite imagery taken on Monday. The town was still under a “too late to leave” emergency evacuation warning on Tuesday afternoon.

The Goulburn River peaked in Murchison at 12.04 metres just before midnight on Saturday. As of 2pm on Tuesday, it had fallen to 10.79 metres and it was expected to fall below 10.7 (its major flood level) overnight on Tuesday into Wednesday.

Echuca

Echuca sits at the meeting point of the Murray River and Campaspe River and has to contend with flooding threats on two fronts.

Floodwaters from the smaller Campaspe River, seen running north to south in the satellite images, peaked in Echuca at 96.25 metres (measured in Australian Height Datum) on Sunday and is slowly receding. By Tuesday morning it was at 95.56 m and falling.

But satellite imagery from Monday shows the enormous swelling of the Murray, which snakes left to right across the image and is the biggest cause for concern in the town now. The mayor on Tuesday morning told residents they have 24 hours to save the town’s CBD.

The Murray River’s height sat at 94.29 metres on Tuesday and is expected to exceed major flood levels on Wednesday.

The river could then peak at 95 metres AHD by Friday. The Bureau of Meteorology notes the river could reach levels higher than the 1993 flood, which measured 94.77 metres AHD.

Rochester

The township of Rochester has been inundated by the Campaspe River, which peaked just after midnight on Saturday at 115.70 metres (measured in Australian Height Datum) with about 1000 homes affected.

In the town centre, business owners returned at the weekend to find the watermark had reached about 60 centimetres up their walls. As of 2pm on Tuesday, the Campaspe at Rochester had receded slowly to 113.14 m

The town’s sewerage system has been knocked out and could take up to two months to restore, and the area remains under a “move to higher ground” emergency warning.

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