Wadi

Wadi (for clarification) is the dried out river that when the rain falls fills up the riverbed and becomes the normal river with flow. And this rivers after short amount of time (when the rain falls) would be more violent with currents being formed but slowly vanishing after more time passes by. I think it would be a new fun event that would make dry and barren biomes (desert and badlands) more interesting to explore and to view. Also when the river dries up again maybe we can see the dead kelp and sea grass with also seeing (if at the right time) fishes dying because of the drought happening.