Houston drainage grid ‘so ob­so­lete it’s just un­be­liev­able’

The Register Citizen (Torrington, CT) - - OBITUARIES - By Seth B or en stein and FrankBa­jak

HOUSTON » Houston’s sys­tem of bay­ous and reser­voirs was built to drain a table­top-flat city prone to heavy rains. But its De­pres­sion-era de­sign is no match for the stresses brought by ex­plo­sive devel­op­ment and ever-wet­ter storms.

Nearly any city would be over­whelmed by the more than 4 feet of rain that Hur­ri­cane Harvey has dumped since Fri­day, but Houston is unique in its reg­u­lar mas­sive floods and in­abil­ity to cope with them. This is the third 100-year-or-more type of flood in three years.

Ex­perts blame too many peo­ple, too much con­crete, in­suf­fi­cient up­stream stor­age, not enough green space for water drainage and, es­pe­cially, too lit­tle reg­u­la­tion.

“Houston is the most f lood-prone city in the United States,” said Rice Univer­sity en­vi­ron­men­tal en­gi­neer­ing pro­fes­sor Phil Be­di­ent. “No one is even a close sec­ond — not even New Or­leans, be­cause at least they have pumps there.”

The en­tire sys­tem is de- signed to clear out only 12 to 13 inches of rain per 24hour pe­riod, said Jim Black­burn, an en­vi­ron­men­tal law pro­fes­sor at Rice Univer­sity: “That’s so ob­so­lete it’s just un­be­liev­able.”

Also, Houston’s Har­ris County has the loos­est, least-reg­u­lated drainage pol­icy and sys­tem in the en­tire coun­try, Be­di­ent said.

Here’s how the sys­tem is sup­posed to work: The county that en­com­passes Houston has 2,500 miles of bay­ous and chan­nels and more than 300 storm-water hold­ing basins, which are de­signed to fill up dur­ing in­tense down­pours and drain slowly as high wa­ters re­cede.

Water is sup­posed to flow west to east through bay­ous, which are tidal creeks that of­ten have con­crete im­prove­ments to make water flow and are con­nected to the Galve­ston Bay.

When big rains come, of­fi­cials also ac­ti­vate two nor­mally dry reser­voirs, clos­ing the flood­gates to col­lect the water and keep it from over­whelm­ing the down­town area.

But the main bayou through down­town Hous- ton, Buffalo Bayou, “is pretty much still a dirt mud chan­nel like you would have seen 100 years ago, just a lit­tle cleaned out,” said U.S. Ge­o­log­i­cal Sur­vey hy­drol­o­gist Jeff East, who is based in Houston.

And be­cause the coastal plain is so flat, only slop­ing about a foot per mile, the water doesn’t flow out of the bay­ous fast, Be­di­ent said.

Also, some of the bay­ous, such as Brays, can only han­dle 10-year storms, he said. Har­ris County didn’t leave enough right-of-way space to ex­pand its bay­ous, Be­di­ent said. And­widen­ing projects have been slow and in­ad­e­quate.

Be­cause of big early 20th­cen­tury floods, Houston de­signed two dry emer­gency reser­voirs that are only ac­ti­vated in heavy rain, Ad­dicks and Barker, both formed by earthen dams. Ad­dicks is 11.7 miles long with a max­i­mum el­e­va­tion of nearly 123 feet. Barker is 13.6 miles long and has a max­i­mum el­e­va­tion of 114 feet.

Nor­mally the flood­gates are open and the two ar­eas are dry park­land with sports fields and bik­ing paths. They were essen­tially dry on Aug. 25, the day Harvey struck, East said. By the mid­dle of the next day, the flood­gates were closed and water lev­els were start­ing to rise, East said.

Now the reser­voirs are overflowing. Of­fi­cials are be­ing forced to re­lease some of the water press­ing against the 70-year-old dams and back­ing up into wealthy sub­di­vi­sions. But those re­leases could worsen the ex­treme flood­ing down­stream in Houston.

More reser­voirs are needed, Black­burn and Be­di­ent said. In fact, an­other reser­voir had been planned for Houston’s western prairies, but devel­op­ment killed that, they said.

Black­burn said stud­ies show those prairies can ab­sorb as much as 11 inches of rain per hour. But he said elected of­fi­cials al­lowed sub­di­vi­sion af­ter sub­di­vi­sion to ex­pand out­ward.

Houston’s storm drain and pipe sys­tem is min­i­mal com­pared with that of other cities and at most can take 1½ inches of rain, Be­di­ent said.

But mostly the prob­lem comes down to hel­ter-skel­ter devel­op­ment in a county with no zon­ing, leav­ing lots of con­crete where water doesn’t drain, and lit­tle green space to ab­sorb it, Be­di­ent said.

Lo­cal politi­cians are sim­ply un­will­ing to in­sist in the lo­cal code that devel­op­ers, who are among their big­gest cam­paign donors, cre­ate no ad­verse ef­fects, said Ed Browne, chair­man of the non­profit Res­i­dents Against Flood­ing.

“In gen­eral, devel­op­ers run this city and what­ever devel­op­ers want they get,” Browne said. His group sued Houston last year in fed­eral court, de­mand­ing more hold­ing ponds and bet­ter drainage.

There are also more peo­ple. Since the pre­vi­ous record flood, in­flicted by Trop­i­cal Storm Al­li­son in 2001, Houston’s pop­u­la­tion has grown more than 23 per­cent, said SamBrody, a Texas A&Mpro­fes­sor in Galve­ston who stud­ies coastal flood­ing.

If that’s not bad enough, Houston is get­ting heav­ier rains with global warming be­cause warmer air holds more water. Since 1986, ex­treme down­pours — the type mea­sured in dou­bledigit inches — have oc­curred twice as of­ten as in the pre­vi­ous 30 years, anAs­so­ci­ated Press weather data anal­y­sis showed in 2016.

Add ev­ery­thing up and “it’s a per­fect mix for the per­fect storm,” Be­di­ent said. “And that’s why we flood so of­ten.”

BRETT COOMER / HOUSTON CHRON­I­CLE

In this ae­rial photo, water is re­leased from the Ad­dicks Reser­voir as flood­wa­ters rise from Trop­i­cal Storm Harvey on Tuesday in Houston.

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