I recently had access to an excavator on my farm property so I went ahead and dug my ponds. I have a general ideas but a little fuzzy on the details and finishing touches so your advice is appreciated as I have been in on this all by myself. I envision the ponds supplying water for my garden and animals (small scale chicken, maybe livestock).
I have currently dug a 90' trench about 1' deep that captures rain water run off from a gravel (millens) road. I placed the spoil on the southern side of trench to act as swale though its is really just a berm and the whole is a diversion drain.
The drain leads to a pit that a dug out in a natural depression in the valley of two hills. I hope to treat the water somewhat here before it enters into a larger pond and/or capture silt. I dug the pond 8'x4'x5' deep. The soil is very, very rocky and quite orange and clayey.
I have a drain leaving this pit to another pond that sits 3' lower on a lower landing of a series of hill enbankments. This will be through a covered/buried pipe so that farm vehicles can travel over. The water will then flow down the 3 foot bank over the course of 10, utilizing flowform fixtures.
The water collects in a pond that is dug to look kinda like a gourd. The long axis is 27', and 12' in the middle. Its wider at one end, hence the gourd. There 2' shelf wrapping around the interior of the pond about 2' down. This soil is loamy for the first foot, but hard clay after that, and not rocky. I have not designed an overflow for this yet but there is another enbankment 10' below that I could divert the water down.
NOW, as I have only dug these features, there is still flexibility to refine my design.
1- Clean and tamp trench to prevent run off. Fill with some gravel (suggestions?) 90' could get expensive. I've considered reed beds in step wise fashion inside this drain as there is about 4' fall over the course of the trench, but Im worried that the force of the water run off would harm the grasses growing in whatever pits I would define inside the trench. Furthermore, they may be dry for some period of time in between rain events.
2- Im debating filling the first pit with gravel and sand to make a horizontal flow reed bed. I am somewhat worried that the walls are two steep as its basically straight down and again, very rocky. I would like a vehicle to be able to travel with 3-4 feet of the pit so, again, too deep? Im also concerned that reed bed would have prolonged drought periods. Does this pit need standing water to support reed beds? Do i need fish to keep down mosquitoes if there is going to be standing water in pit? My family has mosquito concerns :/
3- Do I need to a sealing layer for the ponds? The big one seems like it might be clayey enough at least after a foot deep. The pit, however, is sooo rocky. Im tempted to just wait for the first rain and see what happens? I dont have animals or a chipper to start gleying easily.
4- Havent looked into flowform yet but hoping I can make something cheap. (cut bowls in half?)
In the meantime, Im going to rake the dirt, plant anything I can around to prevent erosion and start seeding. Suggestions there are appreciated as well. Im thinking grasses and reeds to clean, non edibles and edible perennials, and shrubs. I need to find something to put in while l wait for fruittrees to reach maturity.