Martin Tlustos

Hello everyone,

I have this this idea that I would like to float out here for you all to chime in and tell me it's crazy (likely), stupid (possibly), or even catastrophic (maybe) - or that it just might work... ;-)

The scenario: We work in Tanzania, a country that is heavily affected by deforestation, soil degradation and erosion, gullies, sinking groundwater levels and the like. A friend of mine comes from a village where the river has dug down into the soil for more than 30m in the last decades. Massive deforestation in the whole region, leading to flash floods during the rainy season that kill people (mainly women washing clothes in the river) every year.

Of course there are possible solutions for situations like this, like check dams etc. Most of those will fail for two reasons: Lack of money, and lack of vision/willingness to invest money or time into the necessary work.

No my crazy idea/thought experiment: If I could find a running bamboo that has very specific climatic requirements (e.g. not being able to survive in a landscape with more than 2 months of dry season), and plant it down there in the eroded river bed, it might spread out over the whole gully with time, and into the rain water gullies and ravines leading into the river bed, and slow down or even reverse the whole erosion process.

Possible risks:
The bamboo very likely will take over the vegetation in the river bed and the adjacent gullies over time. That's why it is important to use a species that will not grow out of the gullies into the adjacent fields and take them over as well.

Possible benefits:
Reversed erosion wit a low-cost low teck method that can lead to raised ground water levels, a decrease in flash floods over time, and additional resources for the communities.

So now, what do you think? Please roast me, tell me everything that's wrong with the idea and what else could go wrong, lest I proceed with this idea and make a huge mess of a whole region...

Thanks in advance!

We work in Central Tanzania and develop 60 acres into an agroforestry system. It is an incredible joy to see a degraded landscape spring back into live! Three years ago, most of the area was either thorny bushes or bare soil, stripped of everything by cattle and goats...

As said above, access is crucial, and we built our roads and paths along our swales (huge ones, really, they capture about 1.5million litres of water, which is crucial in our area). Additionaly we have set up one big road that circles through the property, which can be accessed by bigger vehicles. From there it is only about 100m max to the end of the fields.

P.S.: Sorry for my English, as you already have noticed it is not my native language... ;-)

Interesting. That is a much smaller "river" than I was visualising.

That's the problem when you're trying to communicate in a language that's not your own... (I speak a very southernish form of German normally ;-)

There are three such things (creeks? channels? runoff gullies?), but they can carry a lot of water and sand after a big rain event (we can get ~100mm of rain within a couple of days).

I will try to multiply the vetiver. plants I have (I got them in Dar es Salaam 500km away). I recently read that pretty much all utilized vetiver grasses worldwide come from one single infertile plant. Very interesting...

 What is your local water supply like?

We have a deep well (150m) on the compound (there is a teacher's college on the same compound). That well only gives brackish water (no water tests yet, so I don't know sodium levels. There is some gypsum in it, though as I can tell from the water taps). We also have two hand dug wells about 4m deep that yield fresh water (though milky). With all the swales I expect water levels to rise and make those wells more reliable even during the dry season (people used to wait for hours for enough water to gather in the holes).

I have put in some sand bags already and will plant vetiver and rhode grasses along the water course. The water has started to run for a few days instead of a few hours already, so it seems to work. I also will try to let the sand gather at more convenient places (near to roads/tracks so we can get at it more easily).

I'll attach a few pictures for your enjoyment... ;-)

Thanks a lot for all the responses!

I forgot to tell that all these creeks of course only have water just after rains, but they can become pretty violent for a few hours.

As I said, we are on very low funds and also want to only employ techniques that can be copied by locals, so gabions won't do here (although they would work great). The same goes for straw bales, they are not available locally/regionally (at least as far as I know).

I have some vetiver grasses that I have started to plant, and there are two other local grasses that seem promising (means when I try to pull them out it is hard work - most grasses are easy to pull out). I don't know yet what species they are (one looks a bit like rhode grass). I will try both.

Chris Kott suggested to build a catchment pond on top. I was thinking about that. One of the rivers goes through a rather flat area up there, so it should be easier to build such a pond. There is a natural small depression at the lower part of our property, but the river fills it up with sand within five hours of strong rains. But still, if I built a dam on top, even if it filled up with sand, I could use the sand as a building resource or sell it, and it might also turn the creek from running for a few hours only into an almost seasonal one...

Digging that pond will take a lot of locals. We had around 150 locals dig our swales, which also meant they are not perfect... ;-) too step, irregular, etc. But we'll keep on improving them... And it meant some income for a lot of people, which is good.

The good thing with permaculture is, it is a growing (and learning) system, so I will try and improve.

I'll make some pictures for comparison from October last year to now and post them tomorrow (it's evening here now)...

Hi everyone,

we have been given around 55 acres by the Anglican Church in Tanzania to build an educational centre and model farm for sustainable agriculture in Central Tanzania (~500mm of rain per year that more or less rains within two months, January and March). Slope is about 2-3%. We only have very limited funds, and the project is aimed at poor farmers, so we try to only use materials and tools that the locals can also afford (shovel, hoe, pickaxe, and that's pretty much it. No heavy machinery).

We have three small sand creeks that bring in tons of sand every time it's raining (catchment area is ~ 0.5km²). I first tried to disperse the incoming water into five big swales I dug across the terrain (~1.8km long, about 1.5 million liters water holding capacity), but the water filled them up with sand and then dug through them in no time.

Right now I use empty concrete bags (we have a concrete blocks company just around the corner), fill them with sand and put them into the creek beds so the sand will slowly fill up the beds. It seems to work so far, sand levels are building up and water keeps flowing for a few days after good rains. Some water also already overflows into the swales as well.

Those sand bags will decompose with time, though, so my question is: how to keep the sand levels in the gullies? I thought about planting grasses that withstand the water flow (like vetiver, but it's not available locally and we don't have a car to go buy it from far away).

Any other thoughts/comments? I'd really like to keep as much water on our land as possible, as it will allow me to grow stuff that wouldn't work otherwise. Water levels have started to rise already, and the lower parts of the area might be fitted to plant avocados, jackfruit, macadamia and other stuff that normally wouldn't work in this area...

Thanks in advance for any helpful thoughts!