Swales in hardpan

Today I found out that we have about 60-80cm of topsoil and the it's just this impermeable hard grey clay.

How do I go about making swales in such conditions?

Yusuf,

I am assuming you don't have access to any machine powered tools, but you might think about people who have tools that might can help. If powered tools are out I would go ahead and outline your swales by moving the topsoil that can be moved with hand tools. This will create a depression where some rain water can settle in and begin to penetrate the hardpan. If you have to wait for rain the swale building will be slow, so you might think about starting with you highest swales first so water can begin to penetrate and move downslope.

If you have access to a broadfork you might see if you can get any penetration with it.

This is all that comes to mind immediately.

Kevin

How thick is this hard pan?

Maybe try planting daikon radish in the bottom of the swale in the hope it penetrates down through the layer if it's only a few feet thick.