This impact crater looks amusingly like a tadpole because of the valley that was carved by water that used to fill it. When the water level inside the crater increased, it breached the crater wall, flowed outward and formed a valley. Sometimes, the water may flow in the opposite direction, like from a channel into a crater.
It is often difficult to differentiate between inlet and outlet channels, but water always flows downhill. In this particular case, we can infer that water is flowing outward because we have the necessary terrain-height information… [More at link]