It flows unimpeded from the higher levels to the river valleys.

It floods the river courses with so much water that they burst their banks and pour pell-mell over the surrounding country.

Many floods which occur in the United States occur because we have cut down large areas of trees which formerly protected the sources of streams and rivers.
A grave danger that threatens western farming is that some time in the future the greater part of the vegetation and forest cover on the watersheds of that section may entirely disappear.

Such a condition would cause floods after every heavy rain.

The available supplies of rainwater which are needed for the thirsty crops would be wasted as flood waters.