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.