This is from an article I read and it shows that Harris County is taking Positive steps towards reducing the flooding in Harris County

"Harris County Commissioners approved tougher development rules in floodplains starting immediately and lasting at least until 2021.

Following the court’s unanimous vote Tuesday, developers must build enough detention to offset possible flooding from new construction in the 500-year-floodplain, or an area projected to have a 0.2 percent chance of flooding each year, in unincorporated parts of Harris County"

The Previous rules mostly were regulating the 100 Year Flood Plain areas ( 1% ) and now have been expanded to the 500 Year ( 2% )

HCFCD staff members say new rainfall depth data collected by the National Oceanic and Atmosphere Administration (NOAA) in December 2017, which includes rainfall from Harvey, shows a 32 percent increase in the 500-year floodplain, a 28 percent increase in the 100-year floodplain, and a 16 percent increase in the two-year floodplain.

These rules will most likely last till 2021 when Mapping of the new Flood Plains will be completed.

The detention areas will be positive for the flooding issues and the impact should be minimal in that many of these areas have been or would have been used as Green Space anyway.