You can build simple drainage holes – here in the U.S. I rented an auger, which is basically a gas-powered post hold digger – but however you do it, dig a hole about 3 feet deep and 1-2 sq. foot wide. and fill the bottom with small pea size gravel…this will give your water a place to drain – you can build as many of these as you want – in areas that have the most water, just make certain that there is a downgrade of the land – so it will seep into these holes – sometimes just planting more plants works, as they drink up the water.

You already know the answer.

make holes in the ground (drill them) as deep as is needed. You need to drill to see if the underground is stone or a very hard kind of soil. Maybe if that is the case you can break this layer in the hole. Put gravel or branches in the hole.

if the soil is very stoney you could try to dig a trench to collect the water and lead it to a low point.