our property was basically flat before our housefire..
when we put in the new house, new laws required that we raise our drainfield and the house/crawl 4' above grade..as we have a lot of water here..so we did..
we had the contractor dig fill from our wettest spot in our field to fill around the drainfield and house to make a nice easy slope down to grade, which made a shallow pond..over the next several years my son got a few hours at a time use of a backhoe and he dug deeper the wet hole to make a
pond, and banks..so although it isn't terrace so to speak, there are now slopes all over the place..
I also have built some raised beds and
hugel beds..
we still have a lot of clay piles from the pond dig to move as well..but yeah, you can change flat land to less flat, and for us here it worked really well.