Nearly 52 inches of rain is a lot, a lot of water. For perspective, it’s equivalent of putting the city of Houston under the Niagara Falls for nine days. And all that water has to go somewhere, it needs an exit. Houston’s bayous, rivers and streams are that exit.

Almost a week after Harvey’s pounding rain has passed, the bayous and rivers of Houston have finally started to drain.

All major bayous and rivers are seeing water levels recede after cresting. Only one location, the Brazos River near West Columbia, is still expected to crest.

That’s anticipated to happen on Tuesday night. The river is expected to reach a level of 31 feet, which is about a foot above its flood stage.

What does it mean when a river crests?

It’s when a river or bayou reaches a peak, a maximum level before water levels drop. This, however, takes time to happen.

Rivers and bayous usually crest well after rain has stopped. It takes hours, even days, for rain to flush out into streams, rivers and bayous; which is why there’s still flooding to be dealt with despite the sun shining.

The good news here is that through this week, all river and bayou levels will continue to drop, despite a few showers late Tuesday into Wednesday.

So just be patient, it’ll take some time, as 52 inches of rain is a lot, a lot of water.