Landcare learning about landscape function

The following post is a reprint of an article published in our local “Landcare Perspective” which is a newsletter put out by the Upper-Shoalhaven Landcare Council (a district level Landcare association, or ‘DLA’). The post was prompted by the article shown below, which appeared in the Winter-Spring 2014 edition of the Perspective….

The Bank Job Article from the Upper-Shoalhaven Landcare Perspective

The Bank Job Article from the Upper-Shoalhaven Landcare Perspective

….and, to a lesser extent by this ‘placestories’ video, which is also about ‘the Bank Job’ project.

The most stimulating aspect of these reports about ‘the Bank Job’ was that they both repeatedly blamed a single willow for causing the 10m deep incision that it was growing at the bottom of! No other causes were ever mentioned.

I could have made my own article more pointedly about rebutting this ridiculous claim, but wanted to avoid embarrassing anyone or hurting anyone’s feelings (I know! Shoot me please!). The Bank Job is a great example of how Landcare is able to motivate volunteer community input. But it’s also an example of how complex and dynamic environmental realities are often dumbed down  to a predictable nonsense: “the willow did it”.

Another educational opportunity missed!

This story is about more than a group of volunteers wanting to do good things in their local environment. There’s a back story of misguided and misdirected ‘experts’ too. If you look at all of the organisations mentioned as contributing to this project, it is obvious there was a considerable investment of wages from various agencies. As such, total project cost would have been more than the $26,000 grant mentioned in the article above.

Anyway….here’s my take on ‘the Bank Job’ and why I think it’s a project that is missing the point. The problem evidenced here is not just one eroding bank, it’s an entire catchment with an elevated stream-energy regime. As a learning community of Landcarers, we need to join the dots and not simply blame the first non-native we see.



Landcare learning about landscape function

Ben Gleeson.

An article in the last Landcare Perspective gave an update on ‘the bank job’, a Landcare project on the Mongarlowe River. Apparently, a willow causing bank erosion was removed, and rock groins installed along with native vegetation, but the bank continues to erode. The article finished with the welcome suggestion that an evaluation of project outcomes now take place to inform future work at the site. I hope that the following contribution will help.

Flow-lines are in the business of handling varying flows of water and the erosive stream-energy that comes with them. If they are functioning well, they slow the water to limit stream energy and associated erosion. There’s a commonplace perceptual maladjustment in this country whereby people see a creek or river and assume that it functions to take the water away; whereas—as a matter of fact—flow-lines naturally develop in ways that will slow the water and hold it back as much as possible. This is achieved in multiple ways: overflowing across a floodplain is one of these, but many flow-lines are now significantly incised, so high flows don’t access floodplains as they once did. Where flows are contained within an eroded channel, stream-energy may also be dissipated by the process of meander development. Figure 1 shows how a direct path between two points of different elevation creates the steepest slope while a meandering route creates a longer path and correspondingly-lesser inclination; this lowers stream-energy and associated erosive force.

Meander diagram

Figure 1: comparison of route length and bed inclination for direct versus meandering flow-lines.

So meanders are a good thing, but how do they form in creeks and rivers? Well, it’s to do with the natural growth of vegetation. During recent fieldwork in an incised swampy meadow near Orange, I studied the development of pools and meanders caused by vegetatively-fixed bars of sediment situated along the base of the incision. Figure 2 compares a 1954 aerial photograph with another image taken in 2013, over this period of time a significant meander (indicated within the black rectangle) has emerged in the course of the incised flow-line.

bar comparison

Figure 2: Aerial photographs from 1954 and 2013 showing meander development in an incised flow-line near Orange, NSW.

The processes which led to this deviation are illustrated in Figure 3. The left side of this figure (A) shows the vegetatively-fixed bar and the pool below it—note the eroding bank on the right and the recently deposited sediment at centre. The right-hand image (B) is a close-up of this patch of sediment 4 weeks later—note how grasses have grown and stabilised (aggraded) it into the existing bar; this bar of sediment is actively growing.

Figure 3: Showing (A) eroded bank and vegetatively-fixed bar with recent deposition; and (B) grasses aggrading deposited sediment 4 weeks later.

Figure 3: Showing (A) eroded bank and vegetatively-fixed bar with recent deposition; and (B) grasses aggrading deposited sediment 4 weeks later.

Peak flows travelling over the bar are slowed and energy is dissipated at this point so that new deposition occurs after every high-flow event. At the same time, remaining stream-energy is deflected into the opposite bank causing erosion and channel deviation. The bar is expanding because stream-energy is lower where the plants have established; the bank is eroding because energy is being deflected to the opposite side from the bar. Over 60 years this process has created a pool–riffle sequence and a meander at this location. These slow the high flows and help dampen overall stream-energy within the incision.

Note that there is no ‘problem-willow’ at this location. This bank erosion is being caused almost entirely by grasses. Does the NRM lexicon have a term to describe these ‘problem-grasses’? This example illustrates the fact that all vegetation able to stabilise sediment is capable of causing bank erosion. Willows are often undeservedly singled out for the status of “problem-species” because they are particularly good at establishing in high-energy locations. Since meander development is a beneficial natural response to excess stream energy, it seems obvious that what we often see in ‘problem’ situations is actually ‘problem-urbanisation’, or ‘problem-property-boundaries’ which have been placed too close to dynamic natural flow-line systems.

The observations presented above demonstrate energy-dissipation processes within an incised flow-line. I suggest this is also happening at ‘the bank job’ site. Figure 4 is an aerial photograph of the bank job with the eroding bank and rock groins indicated. Also indicated is the existence of a gradually-developing bar of sediment, known as a ‘point-bar’, slightly upstream and on the opposite side of the river from the eroding bank. Successional ecological processes are indicated on this bar by a change in observable texture (indicating height or species differences) from upstream to down.

Figure 4: Aerial photograph of ‘the bank job’ showing eroding bank with rock groins and developing point bar.

Figure 4: Aerial photograph of ‘the bank job’ showing eroding bank with rock groins and developing point bar.

This is the initial stage of an energy-dampening repair process: the natural development of a river meander. It is promoted by vegetation spreading on one side of the river (the relatively low-energy side with the point bar) which causes energy deflection and corresponding erosion on the other side. Those rock groins may one day form part of the southern bank of the river! Alternately, they may succeed in preventing meander development, but protecting one part of the stream against bank erosion only exports the erosive energy further downstream, possibly creating problems elsewhere. Taken to an extreme, consistently armouring flow-lines against erosion and meander development promotes a higher-energy flow regime throughout the entire catchment, in spite of natural tendencies towards stream-energy dissipation.

As humans we often employ reductive thinking methods. These limit our perception of reality to a manageable problem or threat that we feel able to solve. You can see this happening in Australia right now in current obsessions over ‘the problem’ of asylum-seekers…or Muslims…or willows; take your pick. In each of these cases the underlying causes of the perceived situation are not adequately addressed because “the problem” has been narrowly defined to a single component. Community discourse is constrained so that the subject is culturally-constructed as having no redeeming features whatsoever. As such, “the problem” simply becomes the presence of the demonised subject. The solution must therefore be its removal (like when the RTA wanted to cut down Braidwood’s avenues of poplar). Often, explicit militarisation accompanies the goal of removal: ‘sovereign borders’, ‘war on terror’, ‘willow warriors’. Real causes of various issues, and better-informed ways to respond, are ignored because they are only apparent when we look beyond the narrowly defined “problem” and consider a broader context. Too much time, effort, and money (mainly it’s the money) is currently targeted in NRM to fight narrowly-defined “problems” in ways that ignore and actually undermine natural landscape function.

A more productive way to consider ‘the bank job’ situation might be to re-define excess stream-energy as a kind of water pollution. Like other pollution, it can be ‘point source’ or ‘diffuse’ and it represents a potential resource not being properly diverted or utilised—in this case to replenish nutrients and rehydrate floodplain landscapes. Also like other pollution, if we observe symptoms at the bottom of a catchment we look higher up to find the source.

Stream-energy pollution is embedded within multiple landscape processes, not simply in component features. As a concept it may help broaden perspectives beyond a simplistic focus upon “problem components”, to encapsulate the wider processes driving natural landscape function. A better way to deal with stream-energy pollution would be for upstream land managers to adopt practices which maintain all riparian vegetation and allow natural succession within flow-lines. Instead of armouring banks and exporting stream energy, we could slow and spread run-off using structures that create pools and bring peak-flows out of incisions, back onto their natural floodplains. This would reduce stream-energy thereby assisting natural processes of stabilisation lower down. Benefits would cascade through the catchment: rehydrated landscapes without destructive stream energy. Understanding underlying processes can stimulate beneficial ways of working to support natural landscape function and repair. Members of our Landcare community should pay close attention to ongoing Natural Sequence Farming trials happening in our local area to learn more.

14 responses to “Landcare learning about landscape function

  1. Loved this article Ben on ‘land care learning about landscape function’. The big picture thinking aided by the aerial photographs + the broader ecosystem context. Bit of a quantum leap from the day to day, budget to budget, election to election timeline which dominates in our culture’s thinking and management.

    • Thanks Monica! It’s quite remarkable how resistance to ecological perspectives on landscape function pervades our NRM culture and activities. Perhaps, as you point out, this is a symptom of existing management structures.

      My take on all of this is informed by recent (and heartening) research in Biogeomorphology and Ecogeomorphology. We should expect to see a burgeoning of ‘ecologically-inspired’ approaches in a number of fields (Eco-climatology is another) as various disciplines begin to reconsider the scale of the influence of the biosphere upon the moderate functioning of this planet.

      I couldn’t recommend more highly work conducted by Corenblit and others within Ecogeomorphology. If interested, have a look at this paper for a thorough outline of relevant scientific concepts:

      http://www.aeoliangeomorphology.org/PDFs/Corenblit_et_al_2011.pdf

      Cheers, Ben

  2. Well explained Ben , and excellent reference too . Authorship of an Article of this quality should be a mandatory requirement for any persons trusted with gov money on river works .

    Leopold and Knight are good texts too.

    The ‘ big picture ‘ is that thousands of acres of catchment above the crumbling cliffs have been dramatically compacted by grazing . Penetrometer reads 1100 psi or worse , when pregrazing soils were 100 psi or so .

    This means that , until the catchment is decompacted ( which will not happen as long as cows are legal ) , high flood pulses must be planned for in any works .

    Yet the planners placed groins in the first quarter of the outside of the bend , the ideal position to turn high flows into a destructive vertical axis back eddy .
    And so the undercutting continues .

    Water runs faster and contains more energy on the outside of a curve .
    Planners at Mongarlowe have harnessed this energy to create more erosion .

    An understanding of river dynamics would have led to works designed to bleed off and divert excess energy back into the Thalweg . By convincing the flow to spiral / flip / roll over on the longitudinal axis the eddies will cancel themselves out in turbulence and cavitation . .

    The planners note that the soils are sodic and highly erodible but have done nothing at all to deal with this . Any misdirected energy must continue to cause damage . Even seepage and light rain will continue to attack the banks and make them slump . Protecting them should have been a priority but there is no sign at all of that in the ‘ after ‘ photo .

    Geotextile , Gypsum , lateral ripping from the bank edge , willow logs ( free on site ) , fascines and brush mattresses would have had the bare banks clothed by now . But of course the Nativist narrative precludes use of these powerful techniques .

    So there we have it . $26, 650 + wasted . Not even the consolation that it was a learning exercise as they talk of reinforcing the failed stranded groins with more groins .
    Which brings us back to Bens ominous promise to write an analysis of Landcare corporate structure and functioning .
    In the real world just one failure of this cost would lead to sacking and soul searching . In Landcare the failures are repeated and the ‘ open minded ‘ planners are defended .

    I genuinely , really want to understand why it is this way and how it can be a changed . Help please Ben .

    PM

    • Hi Peter,

      Thank you, glad you enjoyed it. Also thanks again for sharing your own insights and knowledge.

      Have to say I feel sorry for anyone attempting to deal with a situation like the bank job, I was in a similar position myself at the start of my honours project. The goal of this project was to stabilise sheer banks within a much smaller floodplain incision (max bank height 3m) and smaller catchment (6km2). I set out (on advice) to trial two plant species planted directly into the vertical wall (hardenbergia and myoporum). During the course of this project (and since) I wised up to the futility of trying to stabilise a vertical wall of soil. Explaining the complexity of stream dynamics is almost overwhelming, but suffice to say, where you see a 10m deep incision at the bottom of a large catchment, “the problem” is not the willow. This I have tried to convey, as have you in your comment.

      The cause of the historic incision and present-day erosion is an excess of energy within existing flow regimes. Widespread soil compaction is certainly a contributor to this. Whilst the Mongarlowe River riparian corridor is relatively heavily vegetated, a glance at Google Earth reveals much of the surrounding catchment has been cleared for grazing. Soil compaction, a lack of impeding vegetation and significant incision throughout sub-catchment flow-lines will all amplify the erosive force of flows.

      This eroding bank has catchment-scale causes. I don’t think these can be “solved” by expensive one-off projects. Certainly an obsessive focus upon “genetic purity” as engendered by nativist or (so-called) “natural ecologist” perspectives are entirely counterproductive. What is required is an expansive ecological perspective on land management and landscape function, in my article I refer to Natural Sequence Farming as I feel that what Peter Andrews is pointing to is very much related to this bigger picture view, but there are other ways that people have found to engage with the natural function of the modern Australian landscape. Call it what you will, the only thing that will actually repair that 10m deep incision and get the river back up onto its floodplain is a change of mindset and management. Not one driven by nativism, but one driven by ecological perspectives on landscape sciences, sciences that consider humanity, domestic species, and ferals as integral components of landscape (not simply as things that shouldn’t be there in an ideal world).

      You put me on the spot regards explaining Landcare. I know I have promised you and others a post on the legal reality (administration) of Landcare in our catchment. This should be illustrative beyond the usual platitudes. Landcare (as a movement) is composed by the people that participate in it, but it is also composed by the existing social structures these people conform to.

      For now, I’ll point you to an Andrew Campbell quote we have on our quotes page: “For me landcare has always been primarily about social objectives of changing community norms in favour of more sustainable systems and practices, changing the notion of what it means to be a ‘good farmer’, building social capital and helping community leaders trying to bring about more sustainable approaches in their neighbourhood and providing an efficient framework for sharing information and resources.”

      It’s a shame that being “an efficient framework for sharing information and resources” has often been exploited as an instrument for top-down policy implementation, but that is why the vocal and active participation of grassroots members like us is so important. Peter, Landcare’s past failings should not be a reason to disengage (and turn to what? I wonder), it should be a reason to engage with increased vigour. We have a group forum here in which we can discuss Landcare activities, record and register our dissatisfaction with perceived failings and prescribe and document our own improved forms of Landcare activity. There are plenty of malcontents within Landcare. I like an analogy Peter Hazell has made in regard to Landcare, that is: ‘Landcare is like Rock and Roll, no matter how hard people try to institutionalise it and make it mainstream, it always breaks out in new rebellious forms, critiquing and challenging the existing orthodoxy’.

      That’ll do for now. I’ll put some thought into explaining the (slightly squarer) administration side of Landcare in a separate post.

      Regards, Ben

  3. ‘ Catchment scale causes ‘ . Now we’re talking .

    This is a hard subject to air , and a very big problem to address . It will probably take several human generations before we can look at it unemotionally .
    Here goes .

    Apocalypse Cow .

    For a hundred million years hardly a square inch of our continent felt the pressure of 1,000 psi crushing down on it .
    The grass lands , the soil and root fungi , the root architectures of huge trees . All had coevolved under the light ( a few dozen psi ) tread of marsupials .

    It changed forever when hooved animals arrived . In two centuries every square inch of grazing land has felt pressures an order of magnitude greater than ever before .

    Soil compaction is a terrible threat to life in on this continent .
    It makes our land surface water repellent , thats where the flood pulses come from .
    Overland flow can start within a few minutes of heavy rain .
    In the dreamtime it was through flow . Through soft , porous , carbon filled soils moving water clear down to the aquifers of the Great Artesian Basin . Dreamtime rain moved hundreds of miles underground .
    Now days its hard up to move yards .

    Noted that the soils health workshop mentioned in ” The Landcare Perspective ‘ didn’t use the words ‘ compaction ‘ , ‘ soil mechanics ‘ or ‘ soil physics’ . Thereby completely avoiding the vital science and art of decompacting ceramic soils .

    Soils with some clay content fail plastically under compression and shear loads. Civil Engineers know all about it . To make stable foundations for skyscapers the engineers must compact the foundation material until it loses its porosity and collapses into a solid block.
    ‘ Coulombs Equation ‘ explains .

    Exposed to hot sun the collapsed soils go a step further and bake into blocks of ceramic . Tiled landscape , waterproof , airtight . Dead .
    Returning 1,000 psi on the Penetrometer when most plant roots have great trouble growing through more then 350 psi or so .

    Rammed earth wall builders know all about it , too .

    Twenty five years after removing cattle from our farm the ripped soils are verdant and the untreated soils are as dead as ever . We conclude that to decompact collapsed soils you must rip with a greater force than the one which destroyed the structure .

    Deep ripping is not spring tines ( break out at 400 kg ) or bulldozers ( hydraulics of which have huge down pressure making a worse pan ) .
    Deep ripping is a good operator using the wonderful narrow rigid tine inverted kite ( 6 ton break out ) called the ‘ Yoemans Plow ‘.

    Which brings me to a story about the dangers of simplistic announcements and their negative educational value over generations .

    Years ago the ‘ Healthy Rivers Commission came to town .
    It was made clear that they wanted submissions to be clear , short and no debate was to be entered into .

    I said my piece , much as above . ‘ Water repellent landscape , overland flow
    , sheet erosion , sediment polluted rivers . Lets trial some deep ripping technologies .’
    Nothing too controversial thought I.

    When I finished there was a sudden new request to make a submission.
    Respected local grazier took the stand
    ‘ I am the chairman of Braidwood Landcare Group . I tried ripping some of our sandy country and it didn’t work . Marshall is wrong ‘ .
    Smart arse blow -in humiliated and neutralised . Misinformation given the weight of fact .

    There are people who were in that room 18 years ago who still believe that ‘ ripping doesn’t work ‘ . Respected Chairman said so .

    And thats why USLC should not be publishing private opinions as if they are fact . The willow did it , the goats did it etc . New people will believe it , and shape their engagement with the landscape accordingly .

    Ben suggests engagement with USLC . All in favour of it .
    Their last newsletter was a broadside .
    I intend to engage , in the Naval sense of the word . Time to return fire

    The country is running down . We should all be reading Mary White .

    Regards

    PM

  4. This informing article raises a dilemma for me Peter. Just how did you become a ‘champion of the catchment’ before it was written!
    Robbo

  5. I forgot. I agree ‘The ‘country’ is running down, or did you mean ‘country is running down’. If the former is intended then a question is begged; What is the relationship to a proliferation of graduates.
    Robbo

  6. Robbo ,

    I meant ” Running Down ‘ in the sense of Mary Whites books title .

    Or ‘ Listen our Land is Crying ‘.
    Fine , significant books by an author possessed of observational skills and scientific rigour . Skills all graduates could do with .

    Winding down , drying out , soils washing to the sea , nutrient cycles locking up , the highest levels of extinction in the world , landscape depopulated , towns failing , expertise dying away , money wasted , time lost

    Look up at the canopies of the big Eucalypts from Braidwood to Canberra .
    Dying before their time as soil compaction chokes their ectomycorrhizals . They are starving to death .
    A landscape is degrading before our eyes . Running down to iron hard acid ground .

    Better go now to Yeomans the back forty . Good for the morale .

    PM

  7. Thanks Peter: collateral damage, is the term that comes to mind. It takes many twists and turns. First-response is to grow another institution, counter force, school or department. It saves naming the underlying cause, even masks it. Flood creek nonnativist Landcare has called it out. A breath of cool fresh air.

    “Winding down , drying out , soils washing to the sea , nutrient cycles locking up , the highest levels of extinction in the world , landscape depopulated , towns failing , expertise dying away , money wasted , time lost”
    If I had to pick out just one of your above concerns it would be ‘landscape depopulated’. Without a few hands there is only very heavy machinery or chemicals to do the work. Creeping regionalism is likely to fill the void. Depopulating country by another name.

    Sustainable outcomes will remain illusive if, useful and necessary, ‘populist environmental policies’ prevail as the under pinning science necessary to close the gap between viability and sustainability.

    Robbo

  8. In reply to myself replying to Peter after replying to myself!
    Bull dozers are old hat Peter.
    Back in the ‘good old days’ Bill Permaculture spoke of how Oxen powered soil ripping had been replaced by ‘modern lighter technology’ supplied by Fritz Schumacker’s Appropriate Technology Group, to avoid soil ‘compaction’. Instead of two oxen it was two stationary winches anchored at each end of the paddock. Simple, just add petrol and absolutely no compaction. But of course it could be done equally well with two landcruisers.
    Robbo

  9. Sorry , did I confuse on the deep ripping issue ?

    Not Bulldozers . Their tines are designed to rip up roadworks . They create compaction pans both horizontal , at base of toe , and vertical , where the wide tine smears soil sideways .

    Yeomans , AgroPlow / Wallace etc uses a very thin high strength steel .
    The tip engages the soil as an underground kite and fractures concoidally out and up. The toe is not pushing downwards as with bulldozer . Its the forwards movement of tractor , not down pressure by hydraulics which is translated into lifting soil and injecting oxygen .

    Shumacher said a lot of lovely things but never sweated in a field .

    In our local grazing lands the soil compaction is typically 1,000 psi on the penetrometer . To rehabilitate such soil you must apply 7 ton ( sorry to mix metric and imperial , I do that ) forwards pressure on the tine tip .
    Which would have the 2 ton Landcruisers being slowly winched back across the field , anchored by the plough .

    Instructive to note that local soils were once so soft the Aborigines could farm them with a wooden stick .
    As late as 1900 our farm was ploughed with two- horse teams . Try that after a century of Apocalypse Cow and you wouldn’t even scratch the surface . We need 50- 60hp on three tines and at least three passes to break through Coulombs Line now days .

    Conventional unequal wheel tractors are big soil compactors too . Most weight is on the back axle when unloaded . Much worse once implement is attached and ground engaged .
    They will exceed Coulombs Line for most of our local soil types .

    That’s why only Antonio Carrarro low compaction tractors are permitted on our property . The design is equal wheel , with engine in front of front axle . When implement is attached they have exact weight distribution on both axles .
    They do not exceed Coulombs Line for our clay soils .

    Note the big tractors used for broad acre crops are commonly of equal wheel design , to reduce soil compaction .

    As for winches , very useful for selective tree felling . Am in the market for a Trewhella in good nick . Please check your sheds , our Hopi friends would be grateful .

    Ile Castore Ardente

    PM

  10. Hi Ben and Peter
    Thanks to you both for adding and sharing to our knowledge base through your action-based learning’s.
    I’m grateful to PM for his insights and to Ben for his initiative.
    The discussion needs to be aired where it can get enough oxygen.
    I want to alert others to your website and wise counsel.
    Peter you have been a real quiet achiever….time we stood behind your work and applauded the successes and wise counsel you bring to the table.

    • Thanks Duane, for this comment and for your email. I’ve got to say you’ve been doing some great work yourself and you’re right about Peter. We’d be happy to have you share this discussion with others elsewhere and to share any input you may have here. No doubt we’ll keep in touch. All the best, Ben

  11. I can definitely see why you would want to check your soil for nutrients and pollution before planting. I have always been interested in soil depth and how it affects plant growth. My wife and I have been planning on finding a way to start our own vegetable garden, so I feel like a soil penetrometer could be a great way to test our soil’s conditions.

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