I recently purchased a five acre wooded lot, with a slight slope. There is a ~10 foot deep crevasse in the dirt running across the area where I would like to route a driveway. It appeared to be dry the few times that we've visited it, but I suspect that it was created by a seasonal flow or possibly heavy rains. Before we fill it in next year, I would like to make sure that it isn't a dry creek bed. Unfortunately, the lot is 750 miles from home, so it isn't a simple task to check it every time that there's rain. There's also no electric or Internet access available, not even cellular.
Does anybody have an old-school suggestion for a method to detect water movement in a crevasse or dry creek bed? I have thrown some branches and leaves into the bottom, but suspect that they could be moved by wind or undermined (not visibly moved) by a smaller water flows.....