Rice fields have drains of sort to maintain water levels. The one I saw had levees between them, so each field was just a couple of acres. At one end of the field there's a hole cut in to the ground that reaches the 'ground' level of the rice field. Then they installed some railing that you could slide 2x6 boards that would retain (most of) the water.

So with that system, if you got too much rain, it spills over the top board in to drainage areas. The water would never be able to fill past the top board, which was lower than the surrounding ground. Or you could remove boards and completely drain it.

You don't want seedlings fully submerged by spring rain or they won't get oxygen.

Granted this was for a duck blind in a rice field so other systems may well be different.