Actually Houston does have flood plain management requirements

LA Times:

For years, engineers have warned that Houston was a flood disaster in the making. Why didn't somebody do something?

Houston is built on what amounts to a massive flood plain, pitted against the tempestuous Gulf of Mexico and routinely hammered by the biggest rainstorms in the nation. It is a combination of malicious climate and unforgiving geology, along with a deficit of zoning and land-use controls, that scientists...

In the 1970's Houston developed a requirement that all new construction must be above the 100-year flood plain.  This led to new drainage requirements and new minimum building height requirements for areas not only within the city but those in its extra territorial jurisdiction.  The problem with Harvey is that it is about 10 times more water than could be expected in a 100-year flood.

The kind of rain that was dropped in a concentrated time period would flood any city in America including Denver, and in the case of a place like Los Angeles, it would result in huge mud slides that would drown buildings and people.   Zoning or lack there of had nothing to do with this flooding.  The same is true of land use planning.

In the 70's and early 80's, I worked as a lawyer on financing developments in the Houston area.  Flood plain management was a key part of the approval process.  Engineers careful planned both drainage and retention ponds to deal with the problem.  You just cannot engineer something to deal with a 1000 year flood.