Plenty has been written and will be written and talked about regarding flooding in Houston associated with the recent hurricane. More will come from Irma as well.
If you have not read Boomtown, Flood Town, take a gander to get a little perspective as well as some very informative interactive maps. The article includes what could be described as classic local planning dialog that goes a long way in explaining how people end up living in hazardous areas. One example was the former head of the flood control district in Houston in reference to scientists and conversationalists concerned about development in flood areas, "They have an agenda, their agenda to protect the environment overrides common sense". At least from afar, it seems that building 7,000 new homes in the floodways (even more in flood plains) around Houston since 2010 is not a common sense.
Federal policy, state policy and local policy all play a role in flood hazards. Federal flood policy includes funding flood works, funding disaster response and recovery and also subsidizes flood insurance.
In order to qualify for flood insurance communities need to adopt regulations that ideally will reduce the number of claims over time and thus reduce the costs. New flood maps that determine rates and building areas are often met with protest. Houston did attempt to limit development in floodways, but the local political push back from development interests was very hard and effective at reducing controls of development in floodway areas.
From the campaign opposing regulations in the floodways:
"the property owners in the floodway throughout the city, who have invested in these lands, and have expected our lands, our homes, our castles, to be vested as part of our future nest egg, our future investment and future retirement, we all have been summarily sacrificed. The city must revise this ordinance! The way things are going … to all the property owners in the “floodplain”; who knows … you could be next?"
A power point presentation laid out the argument they used: tax base loss, use a study that refutes the original studies (that is disparages the existing studies that back up the plan), property rights (ignoring the damage to other properties) and ague other solutions should be done not this one.