Flood Barrier USA

Houston Rebuilds with Flooding in Mind

Author: Donna Conneely

People across the country were breathing a deep sigh of relief as the long and devastating 2017 hurricane season drew to a close. As cities across the storm-ravaged areas began the Herculean task of cleaning up and rebuilding, many city planners are looking beyond the immediate clean-up phase, and are determined to build in flood control measures that will help to lessen the impact of future storms.

Many innovative and cutting-edge technologies are being examined, and experts from around the world are being consulted. The Netherlands, with its centuries-old struggle against the sea, is particularly prominent as a place to begin looking for answers; here there is a wealth of expertise and battle-tested technology to be found. Now, many cities in the US are seeking to emulate the success of the Dutch people, and officials are finally beginning to understand that we are now facing a long-term challenge that will only get worse as climate change brings more frequent and more vicious storms.

Enlarged rainfall graphic for Hurricane Harvey in Southeast Texas. Author: David M. Roth; NOAA WPC

In Houston alone, there were over 8 million cubic yards of debris that had to be removed before full attention could be turned to flood prevention projects. There is also an acute housing crisis to be solved; a plan must be developed to shelter all those families that were displaced by the destruction of their homes. But even with these pressing and immediate concerns, planners in Houston are already seeking ways to dovetail flood control planning into every step of the recovery process. This is one of the lessons that the country of Holland has implemented well.

The most obvious flood mitigation project in Houston is to protect, widen, and prevent development around bayous and other water-detention areas; just as Holland has done for hundreds of years. Natural bayous and man-made reservoir projects can absorb a lot of storm water runoff, and if designed or improved with flooding in mind these can channel raging rivers of runoff into a desired direction. However, this obvious priority is too often challenged and circumvented. Houston, like all other growing cities in the US, is increasingly running out of real estate for new housing projects, even as the demand for housing is higher than ever. With the loss of so many homes to the hurricane comes a critical need for the replacement of these structures.

Houston planners understand that a high value must be placed on the flood protection value of its bayous, and they would be wise to resist any temptation to drain or build near these wetlands. But real life often has not worked this way in the past. Many developers have demonstrated a tendency to resist zoning laws and regulations that hamper their profits, and to look for loopholes and workarounds that can result in higher returns on their investments. The fact that skirting or getting an easement from zoning regulations can directly lead to floods and loss of the structures only means that there will be more business to be had in the rebuilding of the homes. Therefore, zoning decisions cannot be controlled or influenced by the construction industry!

Houston clearly cannot allow any further damage or encroachment of its precious retention lakes and bayous. City planners cannot permit developers to thwart or ignore zoning laws. This was starkly demonstrated during Hurricane Harvey, when communities that were built too close to the large retention lakes northwest of the city were submerged. Now, as Houston rebuilds, the priority is being placed on increasing the number of these critical artificial watersheds, augmenting and protecting the natural bayous, and on carving out stringent zoning regulations that are carved in granite.

April 16th, 2018  |  Posted in Flood Protection  |  No Comments »

New Study Greatly Expands US Flood Zone

Author: Donna Conneely

A team of UK-US engineers and scientists have presented their findings, after using cutting-edge technology to study flood patterns in the US. The results of the study, which were detailed at the 2017 American Geophysical Union meeting, appear to show that the current flood hazard maps used by the Federal Emergency Management Agency (FEMA) are woefully out of date and incorrect. The official FEMA flood hazard map is used to determine which properties must carry mandatory flood insurance, based on the officially-assessed risk. If the flood hazard zones are incorrectly identified, many properties may be left at risk of uninsured damage or destruction.

According to the team of researchers, there are approximately 40 million people now living within areas that have a 1% chance of flooding each year. This sounds inconsequential at first perusal, but this level of flood risk is also known as the ‘100-year floodplain’. As we know from recent disasters, the 100-year floods are happening with dreadful regularity in many parts of the US, often in locations that have never flooded before! If a property experiences flooding that was considered by FEMA to be improbable, it is likely that the property was not insured — in which case the owners stand to lose everything without compensation- the funds needed to rebuild. This scenario can destroy lives as well as houses.

As the map above shows, as of April 2017, much of the country has already received updated flood maps in the form of preliminary or effective Flood Insurance Rate Maps (FIRMs). Source: FEMA.gov

Although the new study estimates 40 million people living inside the risk zone, FEMA estimates only 13 million people are living within the 100-year floodplain … a substantially smaller risk pool. This means that as many as 27 million people may be at risk of being underinsured or completely uninsured for flood damage because their property has not been determined by FEMA to be at risk. It may be that many of these people are living with a very false sense of security!

Why do the FEMA numbers differ so drastically from the results presented by the UK-US scientists? This is a question of profound importance to the many millions of people who may be risking disaster, as well as to the engineers and scientists at FEMA who compile the statistics to produce the official flood hazard maps. According to the scientists who were involved with the study, FEMA concentrates too heavily on coastal flooding, and not enough attention is given to floodplains close to rivers, which can be subject to flash flooding during heavy rainfall. The new study was conducted with improved scientific techniques that identified every possible flood zone along US rivers, and here they simulated heavy precipitation events. The results of these simulations are a wake-up call to those who own property in these areas.

So far, the results of this alarming new study have not been utilized by FEMA officials, but the agency is aware of the study and is taking a look at the newly-released data. If the results are embraced and translated into action, many millions of people in the US will find themselves suddenly in need of expensive flood insurance. That would be a hardship, to be sure. But with trillions of dollars worth of assets currently unprotected, an even greater hardship looms as a very real possibility.

April 9th, 2018  |  Posted in Flood Protection  |  No Comments »