reservoir
reservoir
reservoir
reservoir
When runoff drains into a basin that has a rounded depression and maintains a stable amount of surface water on a daily basis, it becomes a pond. Pond typically refers to a small body of still water that is surrounded by land.
A convex surface is one that curves outward, like the exterior of a sphere or the top of a dome. It bulges outward and has no inward dents or depressions.
A crater.
The depressions on the Moon's surface are called craters. They are formed by the impact of meteoroids, asteroids, or comets hitting the Moon's surface.
A crater.
Deposition by erosion , could fill a depression , the same erosion creates depressions.
Ocean Basin
Large depressions on the moon are called craters. These are formed by the impact of meteoroids, asteroids, or comets hitting the moon's surface.
Something that is not smooth will not be smooth because on its surface it will have hollows (depressions) and "bumps" (protuberances).