dohboi – No, not the way the Rockman defines a “floodplain”. How the United States Geological Survey defines a floodplain: “The floodplain is the relatively flat lowland that borders a river, usually dry but subject to flooding. Floodplain soils actually are former flood deposits.”
https://water.usgs.gov/edu/100yearflood.htmlThe city or country or real estate concerns can define “floodplain” anyway they want. But it doesn’t change the facts that every square foot of the ground in Houston was deposited by one of the streams that cross the city. IOW every square foot of Houston is that “relatively flat lowland that borders a river, usually dry but subject to flooding.” Did you see the large areas (greater the .2)
f Houston that flooded as a result of Harvey? Guess what those areas were: “the relatively flat lowland that borders a river, usually dry but subject to flooding.”
I didn’t describe a key component of the definition of a floodplain: the region where streams/rivers periodically migrate across over time. IOW every square foot of Houston has been covered (at some time in the past) by anyone of the numerous streams that cross the areaConsider the history of the Mississippi River. When you see it on a map today that’s where it is TODAY. Did you know that at one time the MR once flowed thru an area east of New Orleans? On average it changes channel about every 25,000 years. It’s a hydraulic gradient thing. Those semicircular islands off the coast of the state of Mississippi mark that eastern position of the former MR delta. Did you know that at one time the MR flowed down the west side of the state thru Lake Charles? The entire southern portion of La. is the floodplain of the MR: every square foot of the ground in south La. was deposited from the MR.
Just as very square foot of Houston is “soils actually {laid down from} former flood deposits.”. IOW for many tens of thousands of years every square foot of the area now occupied by the city of Houston has been periodically flooded by the streams/rivers crossing the county. Efforts are constantly being made to keep those waterways from migrating out of their channels. Sometimes it works…sometimes it doesn’t.
The Rockman had to buy his retirement home in the Houston area because that’s where he was working. But being a geologist that could read a topographic map he could buy on the highest land in the region. Which, coincidentally, was some of the least expensive real estate in the region. BTW some of the worst areas flooded by Harvey are some of the most expensive.