Having done drainage engineering for 45 years in the Houston area, what the article says is basically factual. However the context is that the Harvey Storm dumped 43 inches of rain during 4 days over 2,000 square miles (34 inches of rain in four days over 10,000 square miles)!
That was a 500-year frequency rainfall event over ALL of Harris County and Fort Bend County.
FEMA flood insurance is required in participating jurisdictions for property located in areas with elevations lower than the Base Flood Elevation which is a 100-year frequency storm event. In Harris County that is 12 inches of rain falling in 24 hours.
The moral to this story is that where ever you live just because your mortgage does not require flood insurance, that does not guarantee a catastrophic flood will never happen
“The moral to this story is that where ever you live just because your mortgage does not require flood insurance, that does not guarantee a catastrophic flood will never happen”
When mere inches separate the 100 and 500 year storms 100 year flood plains don’t mean much.
In my 30 years of living in the Houston area I learned that 12 inches of rain in 24 hours is not unusual. When I lived there I built on a small hill waaaay out NW at 260 feet and about 60 feet above the invert of the nearest major drainage, Spring Creek. It was a long drive but no flooding ever.
As you suggest, there are no magic safe lines. The hazard evaluation of flooding is a product of risk and consequence. Water in your house is a high consequence event if you don’t have flood insurance. Mere inches separation between the elevation of the Base Flood Elevation and your front door step is a high risk location to flooding. The risk is compounded by change from subsidence, pavement and saturation.
Anyone who hasn’t yet had their basement flooded would do well to heed the implied advice of your statement. Those who didn’t heed the advice wished they had.