MDB fact: How much water do we get from spring melt?

11 December 2015

It’s International Mountain Day so we’ve taken a look at how the spring snow melt feeds the Basin.

As it’s warmed, the snow that fell onto the higher mountains during winter has melted, some of it flowing into rivers either as surface run-off, or more slowly via groundwater. Much of it evaporates.

High country refreshed near Harrietville, Victoria. Photo by Andrew Beer.

But how much does this snow melt contribute to river flows in the Basin?

Well, it’s actually not very much. The area of mountains covered with snow is surprisingly small.

For example, only about 7% of the catchment upstream of Hume Dam lies above the winter snow line. Most of the snowiest parts of the Snowy Mountains actually lie outside the Basin, in the easterly flowing Snowy River catchment.

In the Victorian Alps, the catchment area under winter snow is even less than in New South Wales.

So compared to rain, which provides the vast bulk of flows in the Murray, snow melt has a pretty small effect and is estimated to provide less than 5% of the River Murray system’s total inflow.

Finally, in recent decades, the amount of snow falling on the Victorian Alps and Snowy Mountains each winter has (on average) declined. This means in absolute terms, snow melt is contributing less water to Murray flows than in times past.

Water flows down an alpine stream, Leather Barrel Creek, on its way to the River Murray. Photo by Andrew Beer.

That said, our snowy high country does other things for the system which are pretty important:

  • The snow gets the catchment ready for any heavy rain that comes during late winter and early spring. When there is melting snow on the ground, rainfall runs off more readily and this helps boost peak flows during early spring.
  • The melting snow takes a few months to release all its water. This helps to stretch out and maintain base flows in the rivers, even when there’s not much rain around.
  • Snow melt in the Snowy River forms part of the additional flows transferred to the Basin via the Snowy Mountains Hydroelectric scheme. The reliable nature of these transfers serves to protect the Basin against the impact of drought when Murray catchment inflows drop very low.

Read more about the Upper Murray catchment on our website.


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2 Comments

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How comes then that there is flood exactly when the snow melts? i.e. Oct 2016 110,000ML/day from snow melt alone in the River Murray!!!

This article needs fixing!

Mmm.todd maybe right as in 2012 from drought to flood

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