River hydroengineering sandbox game

I have big time nostalgia for those days as a kid fighting a losing battle against nature trying to dam a small stream running from the woods, across a short beach, and into Lake Superior. I'm sure I'm not the only one, but in order for the game to scratch the right itch it has to be as open-ended as the real thing. This game will need top-notch fluid dynamics and coupling between water and sand. Different scenarios, from "A garden hose running into a backyard sandbox" to "dam the whole river" as the two ends of the scale. In any case, there should be a water source, and optionally a sink like the lake in my story above. Add any measures of success you think are fun, but this might be a make-your-own-fun type experience. Players should be given tools like small shovels or even toy bulldozers to push around sand and dirt, shaping the flow of water in the environment. As they do this parts of the flow of water will be dammed, eventually overtopping and then washing away the dam, making meandering paths downhill while eroding the sand or soil along the way. As the water digs out the sand and undercuts it, avalances of sand should drop into the stream, altering it further. The impossible task of every child engineer is to permanently dam the source. The game should present a space in which the same goal can be attempted but of course, because of physics, never reached. It should scratch the same itch as a stream table watching sedimentation happen and shape the flow of water.