Development has routinely been allowed in floodways

An article in today's Houston Chronicle by Mark Collette and Mike Dempsey (refer to link below) describes how construction of homes in floodways has frequently been allowed to proceed against expert advice. 


Floodways are the areas with the highest risk for flooding damage.  They consist of the channel of a river or stream, plus the adjacent land needed to carry away floodwaters.  The floodway has some of the fastest-moving water during a flood.  The floodways are often bordered by the 100-year flood hazard zones.

The article highlights an example from northwest Houston, where Meritage Homes has proposed to build homes on a 151-acre site on Brickhouse Gully, 2 miles east of the Addicks Reservoir (see map #1).  Harris County and the City of Houston have previously bought out more than 30 homes due to repetitive flood losses and are in the process of buying 15 more.


The Meritage site is also an abandoned golf course, setting up an interesting contrast with the Exploration Green project of Clear Lake City (CLC) on the land formerly occupied by Clear Lake Golf Club.  The Exploration Green site was also originally proposed for housing development but a coalition of local residents and the Clear Lake City Water Authority (CLCWA) was able to stop construction plans and eventually proceed with the Exploration Green storm water detention / greenbelt project (see December 9, 2017 blog post for more information).

The article states that in Harris County approximately 20,000 buildings are in or along floodways.  About 75% of those were constructed before 1985, before the regulations governing construction in 100-year floodplains based on the Flood Insurance Risk Map (FIRM) program went into effect.

In Clear Lake City there are 23 homes in floodways, mostly in Bay Pointe and also in Northfork (see map #2).
Many other homes in these and other Clear Lake City neighborhoods are located partially in floodways or immediately adjacent to them.  All Bay Pointe and Northfork homes were built after 1985, so they meet or exceed the requirement that the level of the lowest floor must be 12 inches above the Base Flood Elevation (BFE). Flooding damage that actually occurred during Harvey was certainly mitigated by these construction standards but also by other factors such as the depth and width of the floodways, especially if they were improved by CLCWA.

CLC residents - are you are aware of the multiple homes located in and adjacent to floodways?  If you live in or near these homes are there local factors that act to reduce or prevent floodwater damage?



Comments

Post a Comment

Popular posts from this blog

Considerations for neighborhood protected by levee

Image
Residents and potential home buyers in areas where protection from flooding is provided by levee systems may need to consider carefully the actual risk, which may be higher than many assume.  Levees are designed to reduce (but not eliminate) flooding risk.  There may often be no requirement for residents to be provided with an assessment of the specific risk by developers. However, the presence of levees indicates that significant drainage issues exist in the area. The levee system (usually composed of earthen berms, flood gates, and pumps) must perform two functions successfully to prevent flooding: Hold back flood water from outside of the protected area Remove water accumulating inside the protected area Failure of the levee system can result from multiple factors such as: Berms must have sufficient height and strength to hold back impinging flood water Gates must operate properly and be opened/closed at the appropriate times  Pumps must operate properly ...
Read more

Check flood control and drainage improvement projects in your area

Image
Residents of flood prone areas are well advised to stay informed regarding current and planned flood control and drainage improvement projects.  These projects by design will result in significant reductions to flooding risk.  In some cases the flood hazard maps will be revised to reflect the reduced risk.  This could allow a decrease in flood insurance premiums for the home owner. In my area I noted a project underway in Nassau Bay, a waterfront community in southern Harris County, Texas that has a history of repetitive flooding.  The project is being conducted by Harris County Flood Control District (HCFCD).  It is located on a lot that I had noted previously as the site of a home buyout and demolition after Hurricane Ike, which caused heavy damage to many Nassau Bay homes in 2008. HCFCD maintains an interactive map viewer on which the details of all Maintenance and Capital Improvement projects can be viewed at the link: https://www.hcfcd.org/int...
Read more

Drainage features without mapped flood plains

Image
All drainage features whether natural or man-made have flood plains, which are simply the adjacent low areas that fill with water during periods of overflow.  Water overtopping the banks will move to all connected lower areas and remain until drained away by other features.  However, these areas may not be mapped as flood plains on Flood Insurance Rate Maps (FIRM).  As a result, residents and property owners may not realize that they are located in a flood zone. Although unmapped these areas will flood during times when the nearby drainage features overflow. This issue was featured in an April 1, 2018 front page article in the Houston Chronicle article entitled "Damage outside flood plain exposes flaws - 'We just need to start again,' says professor about maps designating flood-risk areas".  The article was written by David Hunn, Matt Dempsey, and Mihir Zaveri and can be viewed at the link below: https://www.houstonchronicle.com/news/article/In-Harvey-s-delu...
Read more