high waters in summer

boardwalk in winter

In recent years Lake Gwelup was an ephemeral lake which dried over summer. Historically this wasn’t the case:

“In the previous 32 years prior to 2000, the lake was recorded to dry out twice, since that year the lake barely remained wet once over the summer in 2005/2006.” [1]

receding waters at the paperbark November 2015

In the last few years water has persisted throughout summer, although the level drops. The photo above is from November 2015. I first noticed this change after heavy rains in spring 2013. I wondered how, when Perth’s rainfall is decreasing. [2] I recently found out its due to a change in policy on groundwater use.

boardwalk in winter

Jo Taylor, Conservation Officer at the City of Stirling, said after negotiation with the Water Corporation, groundwater that was previously diverted away from Lake Gwelup has been reinstated. The higher groundwater in the catchment is supplemented by winter rains, which leads to high winter levels.

2 August 2015

flooded paperbarks

5 August 2015 almost an exact replica of the second photo, but this was three months earlier as winter’s water was rising.

flooded paperbarks

And rising more. In September 2015 the water reached the trail, where two months before I stood to take photos.

flooded paperbarks

This month the water has receded far behind the paperbark trees.

the same paperbarks high and dry

In the drier months groundwater persists and although surface water recedes, the lake always has water. The boardwalk is high and dry but the birds are happy with the level before this weekend’s rain.

March water level at Lake Gwelup

The lone Flooded Gum (Eucalyptus rudis) far in the background behind the curve of the water is a prolific seeder. It’s currently out of water but spends most of the year in water.

inundated flooded gum
=^.^=

Reference

  1. Wikipedia (2016) Gwelup, Western Australia
  2. Water Corporation (2016) Gnangara Groundwater System

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