The 2011 Flood at Moggill

The flood waters peaked at 17.87 metres at Moggill on 13th January 2011 according to

http://www.bom.gov.au/hydro/flood/qld/brochures/brisbane_lower/brisbane_lower.shtml

The following close-up aerial photo of the pontoon taken in September 2010 by NearMap will assist the reader in appreciating the PowerPoint titled Farewell to the Pontoon.

This following PowerPoint shows graphically the height of the flood and its devastating impact in terms of its removal of soil and our pontoon.

Farewell to the Pontoon

Alternatively click on the subsidiary page called Gallery of the Pontoon’s Short Life which is a subsidiary of The 2011 Flood at Moggill page on the Menu.

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There was a similar loss of soil in another longer section of our river frontage. If you are interested in the erosion that occurred there and the measures that are being taken to stabilise the riverbank and hopefully prevent further erosion in the case of another flood then please refer on the Menu to the Land For Wildlife page (subsidiary of Wildlife page) and scroll down to Assistance with erosion after the flood where there is a description and photos of the steps that were taken.

The following aerial photographs will give a better understanding of the severity and extent of the flood.

Our property was photographed by NearMap on

13th January 2011 and 25th April, 2010  

and provides a comparison of the bank when it was flooded and before the flood.

On 11th January 2012 our property was photographed by NearMap as:

 

Advantages of the flood

  • some of the most pervasive vines along the riverbank were swept away and this allowed access to areas where subsequently we could carry out weeding of new vines as they appeared and in this way we are more weed-free than ever before
  • several mature Chinese Elms were  totally uprooted or destroyed in the flood – these are one of the biggest pests lining the sides of the river
  • it helped us identify which plants are sturdy enough to be under water for a certain time (the mangroves all died from being submerged in the freshwater for an extended time) or which plants withstood the current when the flood waters were raging or which plants had roots that were strong enough to hold the soil – we have therefore tried to plant more of the same types of plants on the bank
  • some plants have benefitted from being fertilised by the flood water – the flame trees held a line along the top of the bank and 12 months later their leaves are the size of dinner plates
  • a deep layer of debris (small broken sticks) has settled in higher areas and has formed natural mulch for the remaining plants
  • moreover, the flood deposited a layer of sand along the river where the mangroves had been growing – unfortunately this now gave foxes/wild dogs access to the wildlife along the river and Ian, with a neighbour’s help, needed to build a small fence at the northern end to stop  their entry (there is already a fence at the southern end to stop the entry of goats from the adjoining property). The upside of this sand is that we can now walk – in gumboots! – along the river (when the tide is low) and look up at the beautiful growth of new and established plants.

Ironies of the flood (native versus non-native)

  • the dense Guinea  grass (non-native) that covers the slopes of the bank is helping stabilise the fragile soil – and provides something strong enough to grasp in climbing up and stumbling down! It also limits the weeds and provides some protection to the new plants
  • a plant – Cockspur –  which we had been trying eradicate (in the mistaken belief that it was a pest – its thorns penetrate protective clothing and leave sores that can take a day to subside) has a particularly extensive root system and probably contributed to less soil being removed than otherwise would have happened
  • old European olive trees (which created groves along a large section of the bank) also held the soil higher up and supported weaker, smaller plants. We have since discovered that these plants are regarded as a weed but we will not be removing them any time soon although we may limit their further spread

Success story of the flood                                                                                                            

The gully held!!!                                                                                                                                           There was minimal erosion in the gully in comparison to other parts of the bank that lost considerable amounts of soil – although a deeper channel formed in the centre of the gully and a mass of branches was deposited at the two-thirds mark.  This success was due to the rehabilitation efforts of Ian -the laying of carpet as well as new planting and the building of the dam (see on the Menu The Creation of a Sanctuary page and its subsidiary Preventing Erosion).

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One Response to The 2011 Flood at Moggill

  1. Ian says:

    Fabulous work, darling! It looks great and is interesting and informative. You are amazing!

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