My rainwater catchment

I dug a hole in a ditch and put a coat of soil cement and lime mix with 6 inch mesh in it. here is the result after 1 good rain. the soil here will not hold water but soil cement seems to do the trick. its hard to see but there is about 10 000 L of water in this video.

The cost was $150 material $50 backhoe and about 2 days labour for one guy.
here's the link to the video  

here's what a good rain did before the soil cement was applied. thats about 2 or 3000 L of water and it was gone after 1 week. now water lasts for months. I hope. we will see better when the dry season comes

So If a big tank with 5000 square meters of catchment field can work. Why not  small tanks all over  in low spots. If I build some road with soil-cement the road can catch way more rain than dirt can, tanks placed along road. I was thinking maybe just  a narrow strip of sidewalk for motorbike, wheelbarrow and rain catchment.

the holes hold there shape well even with no cement and full of water. I want to dig more holes like these and make buildings using similar mix but with pine needles in one layer of it.  the idea for the roof is 6 inch steel mesh covered with pine needle cement in an arch I have a rebar support frame but its to round I think I want more pitch its stronger that way I think.

I've been infromed that the ponds are almost empty. So I'm going in two weeks to parge at least one tank while I still have wet sand. The concrete was never sealed correctly because it became full of water for 7 months. The first pond the one with no seal at all has filled to the top on one side with silt and sand. The farm next door was plowed like 3 times and they gave it a final plow just before the peek of the rainy season. not all years will be that bad for sedinentation but it has got me thinking that I should build tanks farther onto my land and plant a swath of Napier grass for the water to flow throw and deposit the sand. Then at least I will have pure silt which is more worth digging and using for bricks or fertilizer. ect.

What is your climate?

It sounds like you definitely need to be filtering that surface flow to stop the sediment filling your ponds. Also, if they are filling that quickly then you are losing a lot of soil and fertility!

In a warm climate (frost free), vetiver grass hedges planted on contour would do the trick. There may be some other grasses suitable for your area as well.

No The land next to mine is losing fertility and soil and I am already catching like 95% of anything floating in the water cuz after the first 2 holes which are together the water flows into a third basin where its much clearer. then when it overflows there its got one more small concrete pond to flow through off of my property. There is a smaller gully on the other side of the farm though. That ditch I fixed up a bit with a front end loader and some Napier grass in flow areas it has a low spot to catch runoff but it fills fast and still erodes a bit. I want to build some ponds on that side too. Its less water but it travels down 2 sides of the property (longer distance). This water also starts from the highest point on our land so 3/4 of the farm could potentially receive gravity fed irrigation from a well sealed pond up there.

Ok so I just got back from Puebla and when I got there I learned that tank #2 was actually holding about 6000 Lt of water contrary to what I had been told. Tank #1 had like 10 cubic yards of really nice loose sand and was moist but no liquid water there. So I decided not to put concrete in the first tank and use it as  a sediment tank only. I used the sand to coat the third tank and  the fourth tank.  Tank number 2 has about 2 feet deep of clay at the bottom and is holding water well so I left it alone. I want to put a drain in it because the sealed capacity is 10 000 Lt but the tank holds about 40 000 Lt before it overflows into tank #3 so most of the water going into tank 1 and 2 seeps into the ground before ever reaching tanks 3 and 4. Maybe eventually I'll dig into the dam and put a 6" pipe but for now I'll wait and see how full the other tanks get as is and maybe siphon some from tank 2 into tank 3 which is now sealed very well. Also after tilling the standing corn stalks under with a disk harrow I was able to see the curve of the land better and select a location for tank #5 higher up on the farm and in a separate drainage basin from all the other tanks. I also learned that if I add lime to my concrete mix it tends to crack more, so now I only add lime in the base layer. Lime is needed if you are using soil with clay in it but because I now have pure sand I don't need to add lime and I get a better seal. I added glue to the top layer and more concentrated cement. tank 3 is more bowl shaped because its easier to put concrete on a relatively flat surface.

 

What about using plastic sheet to provide a liner that will be impervious?

Yes. On the sloped tanks I could have put plastic. On the vertical walled tank I tried to put plastic but it got washed in and buried with clay before the concrete was in. The concrete in tank #2 is not finished because it got sediment like 2 feet deep on top of it before it was sealed.

Tanks are filling up again for the second time this dry season. It rained nov 18 or so and I used most of it.  It rained last night and tonight probably and it says strong rain     50mm-75mm. I'm hoping that much rain will completely refill all the tanks to overflow. A wetter winter than normal this year. good summer rains too in 2017.

https://www.princessauto.com/en/detail/6-5-hp-196cc-ohv-gas-engine/A-p8088379e
I got this engine to hook to a pump.

I know I have been very reluctant to put in plastic liners and I may still do that one day. This year I used a new method of sealing tanks with Lime and Used Motor oil . We painted 2 tanks with it for a cost of about $35 It seems to be working quite well and there is minimal contamination in the water from the oil. The oily layer is now buried under a layer of sediment so next year contamination should be zero. I did use some pork lard as well but I was unsure how long it will last, I think it will be digested by some organism. The oil could be digested as well but hopefully more slowly. One thing I learned is you can't mix the oil and the lime and then add water, you get a dry paste that is more like thick tar. It's an exceptional material but can't be spread with ease and goes on super thick so it would cost much more to cover the whole area. The ideal mix is like paint. I used about 5 bags of lime and 40 liters of oil. Normally the water seeped out in December so fingers crossed there is still water now. The hope is to use the water in early fall to finish a crop or have it last until spring and use it to start early in the season before the rain comes. It's a summer rainfall area.

I have to ask where the idea of using engine oil mixed with anything to seal a tank came from.

I cannot see how the water would not become contaminated by the oil.

Holding more water. We're building another big dam on the property line on top of a smaller dam this winter. But I'm going to make all the future dams with wide flat bottoms like a small flood plain where I can grow crops in the moist soil rather than trying to move liquid water around. Another idea is to Canna edulis which can utilize the water later in the year of course it would be pointless to water the corn or something like that in October. And the trees survive the winter on their own so I'm trying to think of a crop where it actually makes sense to use the water in the fall before it dissipates. One year we used it to plant trees in the fall but that is a little bit risky because we might not get more significant rainwater in the ponds until June or July. I made this post because I was going to post a video but apparently I can't post MP4

The idea for the oil came from the use of animal fat and hydrated lime utilized since ancient times. There was a little bit of contamination with the oil. I used about 40 l of oil and probably not even 1/4 liter made it into the water. I started out using the ancient technique of lime and lard but I quickly noticed animals scratching at itand I figured the fungus could probably digest it a lot easier than it can digest oil.

So the guy I hired to do the digging with a backhoe didn't get the memo about the shape of the ponds. My son tried to tell him but he said that he knew how I wanted the ponds. He was going on my original instructions from a few years ago when he dug the first ponds. He dug deep pits with steep sides. So now I have to have the machine back or try coating with oil-lime paint.