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Friday, 12.14.2018
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3:45 PM
More on the Flood Maps

There appears to still be a lot of interest and concern about the accuracy of the flood maps presented at the 29 September 2015 council meeting.

I am of the view that there are significant errors in these flood maps. I gave my reasons regarding this in a prior article on this website called 'Flooding Nonsense'.

A major issue I have is with the way the council proposes to manage areas subject to flooding.

Let's look at what they propose.


Shown on the planning scheme map as SBO3


1.0 Permit requirement

A permit is not required to construct or carry out the following buildings or works:

(If) new fencing with at least 25% openings and with the plinth at least 400 mm above the natural surface level .

The proposed SBO3 is for areas managed by Council that have a known flood issue which requires control, but could be managed without a planning permit. The flood depth in the SBO3 area is usually less than 100mm.

(page 9 Part 1, Amendment C109 tabled meeting 29/09/2015)

The council proposes there be a 0.4 meter gap under new fences on properties effected by overland flows and at least 25% openings in the fence or otherwise a building permit will be required. (Part 2 Amendment C109 Flood mapping of local catchments Page 4). 

I think this is over-the-top and completely unnecessary.

The type of fencing the council proposes be built on land subject to flooding is going to cause concern to owners, sellers and buyers of these properties.

If you have a fence with large gaps under it and gaps in the fence itself, potential buyers are going to ask questions and will be put off buying the property. They will get the impression that this 1 in 100 years floods are a very serious problem and if one comes they could be washed away by it.

I think that what the council proposes is totally unnecessary and alarmist. And I will show later on that I think it helps the council look good before their bosses in the State Government, but it puts everyone else in a bad situation.

I think there is another way to deal with this problem of overland flows.

If you think about the type of floods the council is seeking to manage, it is one in 100 years floods. Most paling boundary fences last around 25 to 40 years in my experience. In a one hundred year period, a paling boundary fence could be replaced up to 4 times. So why are we making this such an fuss and an eyesore for all to see and be concerned about? Why are we putting up these strange fences for an event that may or may not happen once every 100 years?

In my view we should just replace the fences when and if they are damaged by flooding. That would be just as easy and probably would not cost that much more than what we currently do, considering that boundary paling fences need to be replaced every few decades.

Also property boundary fences have traditionally been done at the agreement and cost of the property owners. So property owners will bear the cost. Will the council contribute to pay for the replacement of boundary fences if they are going to be so demanding about the type of fence that must be built? I don't think so. Property owners will pay -- as they always have. So why should council demand things that they neither are responsible for nor pay for?

Also land that is subject to flooding can be identified at the time of sale from the documents that are required by law to be made available to potential buyers. You can usually get a copy of these documents for later reading if you ask. Potential buyers are clearly informed that land is subject to flooding. There is no need to frighten them with these strange and alarmist fences.


So who benefits from these strange fences the council wants built?

In my somewhat cynical view, this proposal regarding boundary fences appears to be in the council's best interest, not the public's best interest.

Please let me explain.

As you may be aware, Manningham council (and other councils) were strongly criticized by the Victoria Auditor Generals Office (VAGO) for not having done enough to manage the flood risks after widespread flooding in the metropolitan area in December 2004 and January 2005.

I think this criticism by their bosses stung Manningham Council.

As I see it, the council prepared these flood maps and these proposals regarding fencing so they could say to the VAGO that they have done what the VAGO wanted and we have done it well. The fact that such a visible show is made of the fencing gives the impression to all that the council is doing something about flooding.

It appears to me that the council have put their own best interests first and resident's interests a very distant second. And this is not that uncommon with Manningham Council.


What can we do about it?

Contrary to what Manningham Council would want you to think, they are not going to listen to your protests. Manningham Council has in the past done what furthers their own interests with the State Government. With Manningham Council the interests of the residents often comes a distant second after their own.

If you are going to get Manningham Council to respond favourably to your requests, you are going to have to apply some serious pressure.

My suggestion is to find as many inaccuracies in these flood maps as possible and then send them back to do the job properly and when the maps are reasonable and accurate insist that fencing is a matter between neighbours.

There is no reason for this strange fencing the council proposes. Fences are not the only thing that  impedes overland flows of water. Brick front fences, house walls, garages, road contours, terraced gardens, retaining walls and many other things will also impede overland flows of water. If anything, the wooden boundary fences will be the first thing to fail to let the water flow.

And there are other ways of dealing with this problem if they do not want to impede overland flows of water. For instance, build normal fences but leave every forth pailing off. Also just leave the plinth off the bottom of the fence. That would leave a 15cm gap under the fence (if we should ever see one of these 1 in 100 year floods). Such fences would not be as strange or unsightly as what the council proposes. If the flood water is only going to be 4" deep, as the council flood maps say, then a 15cm gap under the fence should be adequate to allow the flood water to drain slowly.

And why is impeding overland flows a bad thing anyway? Surely we do not want water to go racing over land where people live, sweeping away gardens, pets and children. Wouldn't we want to provide as many obstructions as possible and let the water slow down and drain at a slower rate?

Consider Ruffy Lake park for a moment. Ruffy Lake is actually a large retarding basin. That is, it is a man made lake designed to capture flood water so that it can drain slowly away through the drainage system. Next time you are at Ruffy Lake look for how flood water drains from the lake. And there are several other retarding basins in Manningham. The idea of a retarding basis is to NOT HAVE flood water race over open land causing property damage and loss of life. So why does the state government think retarding flood water is a good idea, while the council thinks that retarding flood water by fences, etc. is a bad idea? It is all a bit odd.

As you might see, I do not agree with council thinking on this.

If you want to apply some pressure to Manningham Council and try to get them to understand other people's concerns, the flood maps are still available on the council web site. See here

It may be worthwhile to download the flood maps, enlarge the maps so you can see property boundaries then print sections that are of interest to you. It may be useful to go for a walk around these areas to see if you agree with what is indicated on the flood maps. Seeing the property boundaries on your printed maps is important so you can tie the maps in with the places you walk.

Bear in mind that there will be parts of the flood map that make sense. But I found that there are also many parts that do not make sense.

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