We have only 10 inches of annual rainfall in our area. We also have a dry creek 30' wide and 10 ' deep running through our poperty cutting off 2 acres for our house site.However we also have a hard pan on the surface or to just inches below it. So, the area is prone to flash floods. After a winter hard rain for 2 days that may be a total of under 1inch, the creek rises about a foot an hour untill it overlows it's banks. Then the water drops at about the same rate untill there is only a trickle and is bone dry within a week. I hired 3 D9s with land planes to deep rip then level and grade my 19.5 acres, and raise the house site by 3 feet then compact the newly raised soil at the house site , then a ditch witch to trench around and away from the barn site and house site leading to a drain ditch, installed 6" perforated plastic drain pipe and backfilled with rock. I also raise the creek sides by 3feet. Then built our house and barn. No flooding problems at all. It REALY helps to plan for a 100 year flood event ahead of time !