Wow, thank you for all this great advice! So I need a very very strong dam to hold up a river I see. I may have underestimated the power of this river until now. I will send you a video of the river in full flood.

Yes irrigation would be the main thing I will be using the dam for but for irrigation as you may know I need a lot of water so that is why the dam must be large enough so that it will be worth it. The crops which I am interested in growing is alfalfa/lucerne, corn and wheat. Corn and wheat doesn't have such high water requirements as alfalfa but they are also worth a bit less. I might also be interested in fish farming. I would say if I try very hard with a lot of different things like the irrigation, fish farming, tourists maybe, camp sites and fishing competitions it would take me about 10 years or more before I'll start earning profit from the dam if it costs 1 million US dollars. So it is definitely a long term investment but if everything works out and the dam receive good rainfall it will eventually pay off I think.

Yes there is locations where the river is like 20m wide but like I said in my original post I would also like to catch the water from the tributaries of this river if I am going to build a large dam. I saw some earth fill dams gets rocks placed on the inside so that the water doesn't erode away the wall, if I do that and my wall is very strong I shouldn't have any problems don't you think? I would also need a way to release water if the level gets too high. I think they call it a riser, when the level gets to the point it flows down the riser into a pipe and then out at the other side of the dam but they usually also have a emergency spillway too consisting of concrete I think. My worst fear would be not being able to release the water fast enough, that could be catastrophic. The safest but most expensive way would probably be to get a stepped spillway made out of concrete and at the same time you could probably also pour the rest of the wall with concrete aswell instead of the rocks.

Usually there is only a small stream running in the river for about 1-4 weeks or so after the river flooded and there isn't really much water to pump out of the river either as most of it is seeped into the ground quickly. The river bed is made out of fine sand pebbles and stones so the water dissappears quickly.

The river unfortunately doesn't have any natural fish so I would probably not be doing that option as my fish would dissappear in the next flood as you said. Wouldn't the holes also be filled with sediment in floods?

By boreholes I mean holes drilled in the ground by a drill rig. Submersible pumps is then inserted to extract the water. I currently only use them for giving water to livestock and some gardening and self usage.

Thank you for offering. I will have a look if I can get it sampled. What type of soil is needed for the dam build? Mostly clay?

I hope I answered all of your questions so that you can give me some more advise. Please also note that I don't know much about dams so please correct me on anything if I am wrong.

Thanks alot.

Last edited by NADam; 12/02/23 01:50 PM.