hollyhocks, it seems to me that you will have to use the river current to power a pump to get the water from the river to your garden.

Long ago and far away a mechanical engineer told me thhat it was quite possible to outfit a bicycle wheel with paddles and use the water current to turn the wheel which would be connected to a generator. (We were thinking of generating electricity). The river was tidal so that two wheels would have to be hooked up - one for the washing tide and the other for the falling tide. They would have to be mounted on flotation devices to keep them working as the water level rose or fell.

The fact that I am still working hard to earn a modest living is evidence that the ideas never got off the ground.

You will need a Water-Ram(Hydra-Ram)
It uses the flow of the river to pump water upwards.

Do a google search for: spiral water pump
Or visit the link below.

Pooh Bear

Here is a link that might be useful: Spiral Water Pumps