Right as Rain: Part 2

Please feel free to ask questions or make any comments concerning the content of this program.
Peter is the only person ever to have 4 ABC Australian Stories and the previous 2 broke all records.

This tells us that Australians are interested in NSF and want to know more about it.

Our forum is your chance to do that. Some of those who know much about NSF may respond to your posts so please take part in this discussion.

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duane
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Right as Rain: Part 2

Post by duane » Mon Jul 13, 2009 8:39 pm

Everybody knows my bias.

Right as Rain Part 2,was a great program, about a great Australian, whose brilliant insights into the unique efficiences of the Australian landscape will provide landscape and water solutions and a legacy to all Australians, now and into the future.

Well done to everyone at Australian Story!!

RiparianMan
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Wheel re-invention

Post by RiparianMan » Mon Jul 13, 2009 10:19 pm

I've loved all the publicity re. gully/stream/river rehabilitation - but the simple truth is it's all been done before! Leaky weirs are just slightly dodgy bed control structures, the role of which has been well understood for many a long year. Funny how we just seem to need to endlessly re-invent things. I was working with landcare/rivercare groups in the mid-90s doing exactly this sort of work.

duane
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Post by duane » Tue Jul 14, 2009 1:46 pm

Hi Rick

It would be good to inform the forum of the work you have/are doing in this area and to see where there might be similarities, differences and add to the body of knowledge about the unique features of Australia's hydrology.

IT WOULD BE GREAT to engage this forum.

RiparianMan
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Post by RiparianMan » Tue Jul 14, 2009 4:59 pm

Hello Duane,
Working as a landcare co-ordinator on the mid-north coast of NSW from 1995 onwards I was involved with numerous projects dealing with the issue of river bed & bank erosion. I then went on to work for the old DLWC's Rivercare program. Channel bed lowering, & its impact on floodplain hydrology (not to mention bank erosion) was well understood. Many bed control structures were designed & trialled - with the specific aim of raising the bed level in degraded creeks etc. Some of the first of these were built in the Nambucca River in the early to mid 90s. Designs built from both rock (eg "rock ramps") & timber (eg timber V-weirs) were perfected in the following years - although with the demise of DLWC (& the old state-wide Rivercare program) much of this work seems to be have forgotten, or is being re-learnt by the current CMAs.

duane
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Post by duane » Tue Jul 14, 2009 9:03 pm

Rick

Thank you for your reply. I am really interested to hear a lot more about this work that was done in those times and the comparisons with the present River Styles system many of the CMA's are using today.

I would love to hear about the methodology, the rationale used for placement of bed control structures, the proposed outcomes and the real outcomes, the attempted 'bio-mimicry' materials and methods used, the successes and the failures.

This would be am invaluable learning experience for everyone who visits this site.

I for one would value your experience and expertise.

duane
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Post by duane » Wed Jul 15, 2009 2:38 pm

Both the recent second program on Australian Story, Right as Rain Part 2, and extended interviews are available to watch online at http://www.abc.net.au/austory/

I would love to hear some more feedback from people on what they thought of the two programs and what we should be doing to make it all happen.

People can also go online at the Aust Story Guestbook to read posts there as well as registering and posting any messages they may like.

swampy
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Australian Story feedback

Post by swampy » Thu Jul 16, 2009 4:34 pm

Congratulations to the ABC for presenting as best they could a balanced story on Natural Sequence Farming. It was unfortunate that the naysayers could not be coaxed onto the screen but following the full interviews with all participants it is pretty obvious where the disagreement with Peter's approaches and "establishment" lie. Those differences {the use of Willows for creek stabilisation and weeds for pasture improvement} need further debate.

Contrary to Tony Coote's observation that willows did not propagate on waterways on his land, the general observation travelling throughout Australia is that these are aggressive colonisers and have spread far wider than their original plantings. Blackberries are an enormous nuisance, tying up large tracts of bush where they have been allowed to grow unhindered. I do find it hard to accept that these plants should be part of a solution.

The sequence of transition that Tony suggested that willows make way for other more suitable species, like Casuarina is a very important theory that needs clarification. If it does happen then this may be acceptable. However, from my observations it doesn't. Willows just take over and dominate a stream once they have gained hold and rarely relinquish their stranglehold.

However, the idea of hydrating the land by slowing down the flow of water and using natural structures and vegetation to achieve this is a basically sensible idea. I have an idea which may be more compatible with the overall desire to re-hydrate but using vegetation that is more in harmony with the native landscape.

What about using vegetation that is native and does a good job of forming dense fibrous root systems that cope with some flooding, in particular bullrushes? These are native, low growing plants that thrive in wet conditions and leave some open water for fish-life to proliferate as well as water plants which do require sunlight. A dam could be constructed so that a wall within a wall would exist where the bullrushes are fed the first bit of water entering a pond in a low mound constructed around both margins of the pond.

This ring pool would receive the first amount of water to flow into a dam following a dry period and would help to keep the border of the pond moist throughout the year. Once sufficient water entered the pond, this boundary wall would be over-topped and the main pond filled from the edges in and not the single entry point of the in-flowing stream. The result would be a permanent ring of vegetation {bullrushes, melaleucas, casuarinas etc - native plant species and all naturally occupants of river systems in Australia}.

This wet edge would allow vegetation to continually grow on the margin of the pond, even though at times the centre may become completely dry. It is this vegetation that gives the pond wall its strength, along with soil that is only rarely over-topped.

Another thought is that most of the structures that are shown involve handling excess water by allowing it to rise above an engineered lip and then flow over the top and downstream. Whether this is through a "leaky" bed of rocks or a concrete wall it still means that once flows reach a certain level they go over the top and in doing so gather momentum as they tear over the wall and tumble into the next pond below. Sometimes they erode their way through the substance of the wall as well, destroying the pond.

What about as an alternative of making a submerged drain that has a graded inlet, covered in mesh and in turn covered in gravel - nature's perfect sieve. The drain could be V-shaped so that with low water levels a trickle goes down and as inflows increase, so does the width and depth of the drain which can hopefully handle a flood.

The outlet could be placed deeper in the downstream pond so that the agitation is reduced, preserving the structures there. The outlet could also travel away from the stream, fill up a side depression forming a shallow bog and wetland and from there water could trickle back down into the main stream. This way, over time the wetland so created is widening, further enhancing the effect of hydrating the whole flood-plain and not just the main channel.

The big problem with my idea is that in a flood it all gets over-topped and that is where the damage occurs. I guess I was hoping that the plumbing, being kept clear of choking vegetation by being behind a gravel sieve will never get blocked and as long as its dimensions are fine, would handle all but the most extreme inflows.

I would be interested to hear how this is received.
Peter Marsh

RiparianMan
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Post by RiparianMan » Thu Jul 16, 2009 7:50 pm

Ok there is way too much going on here to cover it all properly, but here's some "rules of thumb":

Choosing vegetation for erosion control is a major issue. The idea of "tractive stess" needs to be considered. This is a simple concept - some types of vegetation/species have evolved to cope with the force of flood waters & some have not. Unfortunately many of the common riparian weed species, e.g. Blackberry, Lantana & Privet, can handle only low to moderate levels of tractive stress. Consequently, when these species come to colonise parts of the channel that experience high tractive stress loadings during floods they just wash out leaving bare, exposed banks. Weed control for channel stability should therefore focus on removing these weeds from erosion prone sections of channel first