Chattanooga Times Free Press - - OPINION -

We’ve just lived through the wettest 12 months in the Ten­nessee Val­ley’s 131 years of recorded rain­fall his­tory, ac­cord­ing to the Ten­nessee Val­ley Author­ity.

From Oc­to­ber 2019 through Septem­ber 2020, the Ten­nessee River basin was drenched with 75.74 inches of rain­fall — 50% more than nor­mal. Also, for the first time, rain­fall has been above av­er­age ev­ery month for 12 con­sec­u­tive months.

Now, did we men­tion that Hur­ri­cane Delta — ex­pected to pick up left­over en­ergy and mois­ture from down­graded Hur­ri­cane Gamma — ap­pears on track to af­fect the Ten­nessee Val­ley re­gion this week­end, pos­si­bly bring­ing an­other couple of inches of rain or more to us, ac­cord­ing to the Na­tional Weather Ser­vice?

“There is def­i­nitely a cycli­cal na­ture on hy­drol­ogy, and we have tended to see pro­longed pe­ri­ods of heavy rains and droughts in the past,” said James Everett, man­ager of the Ten­nessee Val­ley Author­ity’s River Forecast Cen­ter. “But the past three years have been the wettest years on record and have re­ally been ex­tra­or­di­nary.”

That “but” is telling. The ex­tremes are be­com­ing more ex­treme.

At­mo­spheric scientist Kather­ine Hay­hoe in late Septem­ber spent an hour talk­ing with Reuters and ex­plained it this way: There’s al­ways been se­vere weather, she said, but cli­mate change “is load­ing the dice against us” and mak­ing those se­vere ex­tremes big­ger and more fre­quent — like this year’s record 10 hur­ri­canes (once Delta comes ashore) to hit U.S. coast­lines. Even now, in early Oc­to­ber, there are eight more weeks of hur­ri­cane sea­son.

And, no, Hay­hoe is not just an­other “rad­i­cal” who worked on the Nobel Peace Prize-win­ning In­ter­gov­ern­men­tal Panel on Cli­mate Change. She is known as an up­beat evan­gel­i­cal Chris­tian who stud­ies cli­mate change and finds no con­flict be­tween re­li­gious faith and sci­ence.

But let’s talk just about Chat­tanooga — our won­der­ful city that strad­dles the Ten­nessee River — Amer­ica’s fifth big­gest river and the drainage route for rain­fall runoff from more than 20,000 square miles in parts of Ten­nessee, Ge­or­gia, Vir­ginia and North Carolina.

That’s makes our city the most vul­ner­a­ble com­mu­nity for flood­ing in the re­gion. And if our rain­fall con­tin­ues at its cur­rent pace, the cal­en­dar year 2020 from Jan. 1 through to Dec. 31 will be the wettest one on record, wash­ing away 2018’s record high year and swamp­ing the re­gion’s sec­ond high­est year on record, 2019.

Now lets talk about in­fras­truc­ture — the dams that help con­trol that mighty river that makes Chat­tanooga all that it is.

Be­fore the cre­ation of TVA in 1933, Chat­tanooga was nearly com­pletely un­der­wa­ter dur­ing ma­jor floods in 1867 and again in 1917.

In 1867, the city’s worst-ever flood, rag­ing wa­ter de­stroyed the city’s only bridge over the river — a gap that took 24 years to fill — and set back the rail­road town’s re­cov­ery from the Civil War.

In 1917, the river flowed down Main Street and left about 4,000 peo­ple home­less — about 8 per­cent of the city’s then-pop­u­la­tion of 50,000. Those and other floods prompted city of­fi­cials to haul in fill dirt from high spots to make the sec­ond floors of many down­town build­ings into new first floors, turn­ing the orig­i­nal first floors into base­ments. We call that labyrinth of his­tory Un­der­ground Chat­tanooga.

Sure, we still have flood­ing — ask East Ridge res­i­dents and oth­ers who live along Chicka­mauga, South Chicka­mauga and North Chicka­mauga creeks.

But the net­work of 49 dams on the Ten­nessee River and its tribu­taries built by TVA — the fed­eral agency cre­ated by Franklin Roo­sevelt to help make jobs dur­ing the Great De­pres­sion and bring eco­nomic op­por­tu­nity to the South — has averted $780 mil­lion of flood dam­age in Chat­tanooga and nearly $1 bil­lion in dam­age in the re­gion just in the cal­en­dar year of 2020, ac­cord­ing to TVA. That es­ti­mate rises to $9 bil­lion if the lens is widened to in­clude TVA’s 87-year his­tory.

How­ever, more than half of those dams — 29, in fact — aren’t just flood in­fras­truc­ture; they’re also green in­fras­truc­ture. They pro­duce power. Car­bon-free power. Pol­lu­tion-free power. Re­new­able power. And about 10 per­cent of all power pro­duced by TVA.

We could say Roo­sevelt was a Green New Deal so­cial­ist look­ing for re­silience in a chang­ing world be­fore any of that was cool. And clearly, as cli­mate change es­ca­lates, we need to be just as vi­sion­ary as Roo­sevelt was.

Hay­hoe, with Reuters, talked about that kind of vi­sion and about hav­ing hope in a world with wors­en­ing cli­mate change. She said sci­en­tists like her have done the world a dis­ser­vice by choos­ing “con­ser­va­tive ranges” in talk­ing about the prob­a­bil­i­ties of cli­mate change and its im­pacts.

Sci­en­tists tend to err on the side of what one study calls “least drama,” mean­ing they tend to agree on the low­est com­mon de­nom­i­na­tor. But while work­ing re­cently with in­fras­truc­ture en­gi­neers to de­sign “re­silient” bridges, roads and cul­verts against “record” weather events, she has adopted a new view.

“The big­gest les­son we learned … was that an en­gi­neer’s def­i­ni­tion of con­ser­va­tive is ex­actly the op­po­site of a cli­mate scientist’s. An en­gi­neer’s def­i­ni­tion of con­ser­va­tive is the worst case sce­nario, times two or four or, if they’re very con­ser­va­tive, 10. Be­cause hu­man lives are at risk. … I think the en­gi­neers have it right. Be­cause if it’s hu­man life that’s at stake — if it’s hu­man civ­i­liza­tion that’s at stake, and that is what re­ally is at stake — shouldn’t we be erring on the side of mak­ing sure we re­ally will be okay rather than just giv­ing our­selves a 50/50 chance of mak­ing it?”

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