Not sure if this is something the community here has interest in.
A section of the creek bank has fallen away, revealing that all of the soil has been recently deposited (~ last few decades). The garbage inclusion likely spreads for dozens or maybe hundreds of cubic meters of earth. We don’t want to disturb the soil to clean this out so we’re limited to surface level cleaning.
On the flipside: it’s lots of deep fertile topsoil. The fast growing weeds, like lantana, absolutely love it.
It’s probably been very well shielded from UV rays. Likely still soft and pliant.
Alas if I pick at it I think the bank will fall apart further. The creek water is about 2m away from this (right at my feet) and during storm surges this area is underwater.
I’m joking!
As it is, a sheer wall would need battering and planting but if I know my industry well, you might be just there just to do weeds and you ignore the actual systemic problems like erosion.
Yep.
We’re trying to find out how to fix this – including talking to various local gov groups – but it’s a problem larger than what we can fix with just our volunteer’s hands & (little) authority.
Just that part or is there a lot more sheer walls like that?
This was one bad spot that we chose to clear the lantana from so we could inspect it.
The rest of this section of creek wall (1-2m high) is retained by lantana and other weeds, so it’s hidden and less obvious:
(We don’t want to clear the lantana from the rest of the banks, despite it being a weed, because it’s retaining them. Removing it will probably send all of the soil downstream)
You think it’s all channelised and cut under that? About the same height?
Is this a drainage reserve or a gully? Not a lot of water there. Does the watercourse have its own reserve or does it push up against property? If it has room to move, you can try some techniques from “Let the water do the work” - https://quiviracoalition.org/2018/03/06/erosion-control/ - https://quiviracoalition.org/2018/03/06/induced-meandering/ - https://quiviracoalition.org/product/let-the-water-do-the-work-induced-meandering-and-evolving-method-for-restoring-incised-channels/
Getting local government to be involved is difficult, did you make any headway? Guerilla gardening is usually the only thing that works on the small scale.
Any rocks out of the watercourse around? Big enough that the flow of water won’t move them? Battering with a mattock, shovelling the soil up to the flat, mass planting at 10cm centres with your local sedges and grasses (as close as you can get them), and protecting the toe with some bigger rocks is how I would do it if it wasn’t a crazy large area.
You are going to plant behind the creek edge? Like clear up to/near edge and regenerate?