Clay Bottomland with Swales?

I live in a bit of a valley with gently sloping land. When it rains, I have standing water in areas and squishy ground for a good week. If I dig, water usually fills the hole within 48 hours. The earth is mostly clay with some (1 to 2 inches?) good soil on top. I can get up to 48" of rain a year.

My questions: Would swales help? Is it possible to have swales help drainage in wet weather but keep moisture in hot summer months? Is there a happy medium? When it rains, the water really moves through the land. Would swales cause the water to move slower causing a back up of water making the land flood?

Tools I have to work with are small tractor, subsoiler, small plow head, boxblade, backhoe, front end loader, post hole digger, and old fashioned shovel.

Thanks so much for suggestions and comments!

Do you have access to junk wood? a hugel-swale sounds like what you need down low. The wood is the extra sponge (and nutrient) and gets the plantings up out of the swamp.

A subsoiler running key lines at the top of your property helps it soak in before it makes a swamp down lower. They really do a lot of help to pastures for very little money/time input.

Swales will helpslow the water and sink it deeper. The ends of your swales can also have some overflow if you just have too much water for your property size.