If the water comes The dam collapsed (reduces the speed of the water flow down the Woods.) The rock formation is the formation and flows down into the Weir below.
If water has a water dam will collapse (reduce the speed of water flow down the forest) rock formations arranged, it will break down and flow into the dam. Below
If the water front, water weir would crumble to reduce the speed of the flash flood (down) caused by stone, will be broken, and flow down to the business. Below.