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What to do with the "Toilet Bowl" ravine?  RSS feed

 
pollinator
Posts: 419
Location: Western Kenya
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Hi All,
I wanted to put a question to the group...
On our piece of property, we have a section I call the "Toilet Bowl" Forgive me, I don't know all the proper geologic vocabulary to label it with - its like a ravine(?)... or a severely eroded spring-fed swamp that eventually drains out in a slow moving, narrow, shallow creek(?).  I tried to sketch up a simple diagram, I hope I can post it here. The orange lines are the water-ways.  The purple dots are springs.  The blue "L" shape represents the "Toilet Bowl".  The drop-off is sudden and steep, almost completely perpendicular in some places, and it goes down 20-40 feet, depending on the elevation of your starting point.  It is fed by multiple small, slow, but constant springs(?).  The water table is such that it is possible to dig down and open a new spring (which is what our neighbors to the right did when surveying put the main water-way on our property, and not in his as was previously assumed.)  Apart from the springs, all of the erosion run-off from three properties "flushes" into the toilet bowl during the heavy rains, as all of them have a gradual slope toward the toilet bowl.  As it is at present, there is a section of the "bowl" which is quite nice for cultivating (The left hand side of the inverted "L" in my diagram.)  The soil isn't great, its kind of gravelly from the "flushing", but the water table is high enough to keep things growing nicely during the dry season - and it is here that I produce my dry-season vegetables.  There are also bananas and casavas in the higher areas.  The green square, by the way, is our fish pond, which is fed by the springs to the left, then drains out into the main line.  Pretty much everything below the green square is swampy, especially during the rainy season.  I have taro root planted here - its happy in the muck, and will even grow in standing water.  Its also a great cash crop, with one small tuber going for $1 USD, and a large tuber going for $3.  (Thats a lot of money here in Kenya, where the average person only makes about 1.50 USD a day.) 

So my question is... what to do about the toilet bowl?  My neighbors (to the right in the diagram) have dug multiple channels to drain their swampy places, and are cultivating vegetables (not very successfully) in the inbetween spaces.  My husband (who hates farming, but loves giving his 2-cents) believes we should do the same, along with "cleaning out" the waterways - removing the silt build up, digging them deeper to make the water drain out of the bowl faster.  IS there any benefit in removing the water from the bowl "faster"?  I'm kind of the opinion that its okay the way it is... and if anything we should be keeping the water in the bowl and utilizing it better.  I am more concerned with the edges... stablizing the eroded off banks so that more of our farm doesn't get "flushed" down the toilet! My husband does NOT like the idea of putting in swales - as he is opposed to any standing water on the top-side.  Mosquitos = malaria here.  (However, I'm thinking the water wouldn't "stand" long enough for mosquitos to be a problem.) Any thoughts?
Toilet-Bowl-Diagram.jpg
[Thumbnail for Toilet-Bowl-Diagram.jpg]
 
pollinator
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Interesting, obviously you are halfway around the world, but from what you describe it sounds a lot like what I have on the edge of my farm here in Maine as well.

Being from half way around the world I am not sure I have a qualified answer for you, but I know on my farm I try and control water. That does not always mean retaining every drop drop though. This is Maine where in the last 20 years we have gotten an INCREASE of annual rainfall of 5 additional inches. Already at 60 inches a year, we often times have too much. So in certain areas this farm has swales where I try and contain the water, and in other areas I have ditches where I try to shed the water. A lot of this is figured out for me by soil type.

Like you, I have gravely loam type of soil, so it peculates quite well. Even then, the practices we have chosen over that last few generations here have caused our soil to get on the high side of organic matter which impedes that peculation, so those swales and ditches are becoming of even more importance. In the area you and I have that seems similar...which, by the way I call "The Bowl" interestingly enough, the soil is over in organic matter and is basically clogged up. Water does not drain well. Because of its topography, if I was to ever get to addressing this area for agriculture, I'll use ditching since the soil itself is already retaining too much water. Now honestly, I don't foresee this as I have other areas of my farm that is better suited to agriculture.

But here is the main thing, my main commodity on this farm is sheep farming, and I do take winter feed off many "wet" fields. Now around here the common way to deal with wet fields is ditching and drain tie, but it is not the only way to deal with it. The farmers do that because they use wheeled equipment and hay. The truth of the matter is, rather than fighting wet ground and planting crops that like dry feet, they could just plant crops that like their feet wet. For instance wetland grass is especially palatable by sheep, and it makes excellent winter feed. The problem is it matures quickly since it grows so vibrantly, yet the farmer has to wait until mid summer when it is super dry to harvest that type of fodder. When they do its well beyond prime ad the livestock don't care for it. The farmers then make the silly claim that livestock don't like that type of grass when nothing is further from the truth, they just don't like it when the farmer is able to cut it. My approach on some of these wet fields is to cut it when its in its prime, into silage instead of hay, and with tracked equipment instead of wheeled tractors. In that sense I am not fighting the ground I am farming, either in making it try to be dry, or in fighting mud.

I bring all this up so that you might look at your trouble spot in two ways: that retaining every drop of water is not always practical, nor warranted. Certain soils and topography allow the shedding of water. Or by thinking abstractly like I do, that you may be able to plant something edible that does thrive in that type of soil.

As for the name "Toilet Bowl", I love it and might just have to rename my area the same. I also have another area on my farm I call "The Bottoms". Maybe I should call it "The Backside".

 
Maureen Atsali
pollinator
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Location: Western Kenya
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Hi Travis, Thanks for your reply.
I'm from Vermont originally, so almost a neighbor.
One of the reasons I love where I am is that... even though I'm half way around the world in Africa... the landscape and the weather actually reminds me of home.  (Without the nasty winters, thank you very much!)

I should note about the soil - its gravel-ish in the bowl, but up top, on the rest of the farm is clay. 

Another note - everything here is done by hand... mostly by me.  No tractors, backhoes, or other heavy equipment.  Which puts some limitation to how much "earth works" I can do for myself.  If we do go ahead with my husbands idea of "cleaning" the water lines, I'll hire some strapping young men to do the work.

And yet another note to my original post:  This is a place that is drought-stricken for 3 months out of the year.  It really is a great blessing that we have a reliable source of water on our property.  This water also flows down the valley and probably serves another 10 small farms on the way, so I feel we have a responsibility to manage it well, for our neighbors sakes as well as our own.
 
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i would suggest sand dams they are basicly small dams that are allowed to fill up with sand in order to hold water crops and trees can be planted on the sand dam
 
Posts: 259
Location: Bendigo , Australia
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As a irrigation Engineer I can suggest that wall of soil you speak of, may slowly move backwards upstream causing more erosion.
This may result in degradation of your soil downstream, and of course destroy the ground upstream as it falls over the escarpment.
If you can send some photos I may get a better idea, of reality, and make some suggestions as to how to prevent further damage if that an issue.
.
 
Posts: 1495
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even distribution
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40ft steep cliffs is no joke. If it was made of granite I wouldn't worry about erosion too much, but yours is made of clay.
What happens if you drain and dry out the soil and it becomes dry, crusty and powdered ... EROSION by gravity, wind, critters, water.
So I think that getting the soil super dry will actually increase the erosion and lost of land.

1) What I would do is slow down the speed and amount of water running down the surface of the "cliff" that is eroding the cliff.
An embankment of dirt, haybale, woodchip, living grass, etc you could even dig down with a swale it too will  slow down the water and give it time to go sub-surface.

2) Next is the actual bank/cliff, I would keep animals off, the bank, maybe your neighbors goat walk on it or maybe your have some.

3) Gabion to stabilize the cliff, or some willow roots every 12inches vertically and horizontally.

 
pollinator
Posts: 1526
Location: Toronto, Ontario
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Hi Maureen.

If you'll remember our conversation from your other post where we talked about the Toilet Bowl, I had suggested low-effort, high-impact sedimentation traps laid on contour to control erosion, and a guild of pioneer plants for surface stabilisation.

I also think S Bengi has a good point where it comes to the gabion walls and water-loving tree roots to anchor the slope where it's too steep for anything to sit on a contour line. Also, I agree that drying out your soil would likely lead to an increase of erosion. You'd be sending your soil down the river to the neighbours, who probably wouldn't appreciate the added sedimentation.

I would suggest that you look at plants and trees that are accused of being water hogs. I would see if you could find local ones, as they would already be acclimatised to your dry season. They will probably not dessicate the soil, as trenching and draining would likely do, but it would take up some of the water resources, making the ground less sodden.

I would see if there is something that does this and will stand up to coppicing. That way, should you find you need water resources returned to the soil during your dry season, all you'd have to do is chop and drop the water-holding plants/bushes/trees, and the corresponding root-zone die-off will release its water under the surface.

I think that between pioneer-driven soil surface stabilisation utilising self-building on-contour sediment traps and a chop-and-drop water hog to regulate soil moisture conditions, you could set your Toilet Bowl to handle flood events, where you want to let the excess water move, but not take your land with it, encourage the infiltration of water at times where this is wanted, and cover the slope with root zones that would help keep erosion from dessication at a minimum.

Honestly, if Taro is such a cash crop, I would see what could be done there. Where you could dig swales (to be clear, swales full of organic matter, or at least filled with coarse grit and/or gravel will let water filter down to the subsoil but won't leave any water exposed for mosquitoes to nest in), I would plan them out as taro rows. I don't know of a Taro guild, but you could put one together based on your observations.

Taro doesn't seem like a hard-sell, even to a non-permie like you've described your husband to be. I would focus on the money aspect, and stack functions by making your rows of taro on-contour.

Also, if you have aromatics that both like wet feet and that mosquitoes avoid, that could be another layer of mosquito protection in addition to making sure that the water level in your taro rows stay sub-surface.

You could even mound your coarse barrier fill over the rows, leaving no possibility for standing water to sit at the surface. In addition to keeping the mosquitoes from breeding in your taro swales, the mounds would act as strainers of sorts, letting water in heavy rain events move through them, but catching sediment and organic matter. If you reinforce them by putting branches and fallen logs or whatever debris material you have handy on the downslope from the swales, they will catch the coarse barrier fill and keep it from being washed downhill and downstream by particularly heavy water events.

Good luck, and keep us posted!

-CK
 
S Bengi
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After you have you slowed down the flow of water and stabilize the soil/cliff.
The next step could be to fill up the "bowl"
So build a wall across the bowl to "dam up the stream".
While you want to trap the sediments to fill the dam/bowl, you actually want the water to flow away freely.
So we are going to make our dam wall leaky, maybe out of something like haybale, it might need a log behind it.
 
Chris Kott
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Location: Toronto, Ontario
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I agree. I think that the methods I outlined speak to that, though on the slopes.

Gradually, just by trapping sediments and organic matter, it should be possible to fill the Toilet Bowl. You could do exactly as S Bengi suggests with the straw bale sediment dam, but do it in steps up the ravine, on contour, and get the hydrology to build nice, sheltered terraces for you.

-CK
 
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