Brook Restoration and Property Setup

Discussion in 'Designing, building, making and powering your life' started by Ashby Pither, Dec 20, 2015.

  1. Ashby Pither

    Ashby Pither New Member

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    Hi All,

    I am currently undertaking a brook restoration project on my property near Nannup in the South West of WA, rainfall of about 950mm/annum falling during winter. We have the St John's Brook running through our property which runs fairly regularly throughout winter and is reduced to pools over summer. The brook runs along the edge of an alluvial floodplain. Our property is basically divided into 2 by the brook with one side consisting of the floodplain and the other side a bit more elevated.

    This is basically the start of our plan and I will be undertaking a permaculture course next year which will hopefully start to pull it all together. I have plans for a swale system on the left hand side of the brook as well as a composting bay system on the ridge. So many little pieces of the puzzle which I havent figured out yet though!!

    I have attached a plan showing our initial plan for the brook restoration. Basically we have a pile of large laterite rocks (very heavy, high in iron) and we are going to construct a few leaky levees using these and large logs in the creek based on Peter Andrew's natural sequence farming methods. I have posted this on the natural sequence farming forum however I am not having much luck in getting any feedback/help and thought that maybe someone here might have some thoughts/feedback. I am also planning to install a contour line/swale in the location outlined. I have a few questions I was hoping someone could give me some guidance on to make sure I am on the right track:

    1. The best location for the levees. Currently I have sited these just before a bit of a bend in the brook and where the flow is a bit faster than other areas. Towards the road end of the brook there is a couple of deep pools which retain water during summer and the water flow is not as fast here. The aim is to try to slow down the water flow and start building some alluvial deposits to try and raise the level of the creek banks a little and hold more water during summer.
    2. Planting of trees/shrubs next to the levees. Should I plant these areas this up in rows with willows or something similar? Is there another native tree/tree which will do the job as I may be getting funding from our local NRM and not too sure if they would be too keen on willows? The entire area can be inundated with water during winter for up to a week at times.
    3. Swale design and location. I have identified what appears to be a sandy area in the middle of the paddock and I have positioned the contour slightly above this area and have raised it at the southern end to try to pull some water off the slightly higher ground toward the middle of the paddock and the recharge area (if you have read into natural sequence methods you will know what this means). Does this look like a good design? Should I go with 2 contours as Peter suggests? If I was to dig fertility pits where abouts would I locate these? The paddock has very good drainage, we had a 100mm rainfall event in one night this year and the paddock was driveable the next day. The soil is a deep silty loam high in organic matter.
    3. Any tips for planting out the area? It is very wet during winter and I am concerned all my plants will was away in the first bit of solid rain.

    Thanks in advance for your help and guidance!!

    Ashby
     

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  2. 9anda1f

    9anda1f Administrator Staff Member

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    Excellent planning map! Welcome to the forums Ashby.
    What elevation change is indicated by your contour lines?
    I believe that it is important to construct your levees wide enough so that no water is allowed to flow around them during high water events (to prevent washout and the resulting change in your brook's path). Siting them to slow down the fastest flowing water is the right idea. Have you considered placing a leaky levee at the upper end of the fastest flowing section and another at the lower end of said section?
    Willow plantings might be the obvious choice but also consider a water loving bamboo (clumping). I'd consider almost anything that likes "wet feet".
    Vetiver grass (Chrysopogon zizanioides) might be helpful too.
    We will be looking forward to following along with your progress on this important project!
     
  3. songbird

    songbird Senior Member

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    i'll just ramble on a bit here. :)

    how long have you been there?

    somehow your plans are striking me as "too much disruption too soon". does the stream really need that much work? is it washing out frequently? is it already a hazard that needs changing or is it ok and you just want to take some water off for groundwater recharge and to make some deeper pools? not that there is anything wrong with doing work on waterways, it's actually one thing i'd love to do myself, but it's also heavy and potentially dangerous to you and to others (moving large rocks, logs, dealing with heavy forces from high flows, etc.). i hope you have others to consult and to help out.

    how well do you know the upstream and downstream landowners? are they aware of what your plans might be? how will you prevent silt from going offsite (plugging their works, affecting their pumps, livestock, etc.).

    unfortunately your picture doesn't tell me which way is uphill. i think the floodplain is to the right from your description.

    is the stream/brook a protected habitat that you can actually change? or will such changes keep fish from going upstream? any endangered species you might affect?

    what permits will you need?

    do you have a good idea what a large flow is really like that you can impede it and not also put the highway at risk (or those downstream if it is the other direction) if your changes back up too much water, collect debris and then get washed out?

    a 100mm rainfall is a huge amount of rain (around here that would put water over our road and flash flood through the gardens out back if my new berm doesn't hold -- as i'm not impeding flow but just deflecting it around i'm not going to create a hazard for anyone downslope from here). were you there when it happened? how did the stream flow then?
    there should have been high water marks of debris that would have helped you out for placing any future works. if you could draw them on the map that would be good to know for planning.

    are you allowed to collect water or hold it back and soak it in? some areas have limits on what can be done. i recall someone mentioning a 10% limit, but perhaps that doesn't apply to your situation or area?

    that all said, if you want to capture water to soak it in look into keyline design principles. i think they are very effective for the restoration of groundwater and for getting areas rehabilitated with as little actual earth disruption. if you can do keyline ripping and avoid movng a lot of dirt that's better for the soil than making a lot of swales. in an area with as much rainfall and a lot of slope you might actually not need swales at all. (you'll lose a lot of topsoil from the disruption of the soil on sloped areas -- if you can do other methods of water slowing and sinking that may be enough).

    the geology of the area and the soils will determine what is actually safe to do so that you don't hold back so much water that it makes your land a mudslide waiting to happen... so another good thing to research is your basic geology. if you know any well drillers in the area you can ask them for input or consultation, also with any geologists at any nearby universities.

    a site visit by someone familiar with the area would also likely be very helpful.

    i'm sure i've missed some considerations, but the above is what comes to mind... :)
     
  4. LeeWilde

    LeeWilde Junior Member

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    Hello. I have absolutely nothing helpful to add but I'm just excited to see someone else from near Nannup, so hi :) I shall follow this thread with interest.
     
  5. Ashby Pither

    Ashby Pither New Member

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    Hi Guys,

    Thanks for the responses

    Ganda1f: The contour lines are 5m intervals, if you look carefully along the contour lines you can see the heights. Thanks for the tips on plant species. Definitely mindful of the water flow and where I have sited the levee is at the fastest section of the flow. I will probably only be able to build one levee at this stage due to funds and just to see how it goes, I would rather build one well so that it holds rather than 2 and have them washed away!!

    Songbird: Currently the brook flows very quickly in a deep eroded channel and dries up frequently. It has some very mature river gum trees (large eucalypts) which are quite sick due to a leaf miner pest which has become prolific in the area lately apparently. My main aim is to slow the water flow down and spread it out over a larger area as opposed to running in a deep channel. The flow of the brook runs from north to south and I have sited the levees so that they are well away from the highway and the neighbour to the north, whose land is slightly elevated and the brook flow is slower, the highway has a bridge which sits about 5m high so no worries there. We were there the morning after the rain event and the water levels were just above the edges of the channel and spilling over into some of the pasture to the east directly adjacent to the brook. We only have permits required if you are stopping the flow of water which I am not doing, simply trying to spread it out. The area isnt protected, If you could see what the further upstream areas of the brook look like where there is more conventional farming happening you would be horrified (basically no vegetation with stock running right through it). The levee is more just an aid as I want the vegetation to be the key thing slowing down the water flow but this will take time. Thanks for the tips on keyline, I have looked into that but I dont know anyone with the equipment to do it in my area and it sounds expensive. The soil is silty to sandy loam over clay at about 10-20m deep so fairly stable.

    I am still not 100% on the location of my swale, starting to think maybe I should hold off on the swale until I have planned what we want to do with that area?
     

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