The soil in the Houston, Texas area can best be described as 'sponge like'. When it rains, the ground absorbs water and swells in the same way a dry sponge absorbs water and swells. Conversely, during dry periods, as the ground loses moisture it shrinks and becomes hard.
A sprinkler system helps solve this problem by assuring that moisture is introduced at a regular interval to prevent the ground from drying and shrinking. But since the ground is not allowed to dry, it's ability to absorb water is greatly reduced. So when the soaking rains do come, there's no where for the water to go and flooding results.
That is why a well designed drainage system is as important to the well being of your landscape as a sprinkler system is.