Kalain Ho­sein

Sig­nif­i­cant flash floods left a trail of de­struc­tion across parts of north west­ern Trinidad fol­low­ing a thun­der­storm yes­ter­day af­ter­noon.

Many road­ways from Mar­aval to east Port-of-Spain were left blocked by a mud­dy mix of wa­ter, tree limbs, rocks and boul­ders, while many util­i­ty poles and lines sus­tained dam­age.

Sig­nif­i­cant vol­umes of wa­ter flowed in­to the Cas­cade Riv­er in St Ann’s that leads in­to the St Ann’s Riv­er, com­mon­ly called the East Dry Riv­er, in east Port-of-Spain, as well as the Mar­aval Riv­er fur­ther west fol­low­ing a 45-minute pe­ri­od of heavy rain­fall.

With rain­fall across el­e­vat­ed ter­rain, road­ways turned in­to tem­po­rary rivers in Mar­aval, St Ann’s and Cas­cade and sev­er­al ve­hi­cles were dam­age while at least two cars were swept in­to the Cas­cade Riv­er.

Vi­o­lent rain­fall be­gan across Sad­dle Road, An­dalu­sia, La Sei­va and Mar­aval short­ly af­ter 2.30 pm and flash flood­ing oc­curred with­in min­utes, as wa­ter seem­ing­ly cas­cad­ed down the steep hill­sides on­to road­ways from out of nowhere.

For those al­ready stuck in traf­fic along Sad­dle Road, flood­wa­ters rapid­ly rose around ve­hi­cles.

The tor­rent from the hills brought tree limbs and large rocks that dam­aged some cars, send­ing many peo­ple scam­per­ing for dri­er land.

As the mud­dy wa­ters moved fur­ther down­stream, the boul­ders and tree limbs caused dam­age to mi­nor bridges, rail­ings and near­by prop­er­ties, par­tic­u­lar­ly in Mar­aval and St Ann’s.

Flood­ing was al­so re­port­ed along Long Cir­cu­lar Road and Up­per Bournes Road, St James.

Fur­ther east, the wa­ter from Cas­cade and St Ann’s met in the St Ann’s Riv­er.

With­in min­utes, the riv­er over flowed, flood­ing road­ways ad­ja­cent to Pic­cadil­ly Street, in­clud­ing Prince, Dun­can, Nel­son and Queen Janelle Com­mis­siong Streets, Mu­cu­rapo Road, Ethel Street, In­de­pen­dence Square (South), South Quay and the Pri­or­i­ty Bus Route.

The East Dry Riv­er car­ried a sig­nif­i­cant amount of de­bris as far as Broad­way at City Gate, caus­ing a night­mare of an af­ter­noon com­mute for those leav­ing the cap­i­tal. For­tu­nate­ly, there were no re­ports of in­jury.

Al­though not as im­pact­ful, heavy show­ers al­so af­fect­ed parts of cen­tral Trinidad ear­li­er yes­ter­day, with street flood­ing re­port­ed in Cou­va.

The Min­istry of Rur­al De­vel­op­ment and Lo­cal Gov­ern­ment has ac­ti­vat­ed all mu­nic­i­pal cor­po­ra­tions across Trinidad to re­spond.

Min­is­ter Kaz­im Ho­sein called on cor­po­ra­tions to adopt an “all-of-cor­po­ra­tion” ap­proach.

Ac­cord­ing to the min­istry, equip­ment and re­sources from the var­i­ous mu­nic­i­pal cor­po­ra­tions, CEPEP and the Min­istry of Works and Trans­port were mo­bilised to as­sist with the clear­ing of de­bris and sed­i­ment caused by the heavy rain­fall.

What hap­pened – A link to cli­mate change?

Yes­ter­day, three fac­tors came to­geth­er, which is typ­i­cal for the wet sea­son. First, high tem­per­a­tures near the sur­face of the earth caused moist air to rise. This ris­ing mo­tion was fur­ther aid­ed by sea breeze con­ver­gence, where light west­er­ly winds col­lid­ed with pre­vail­ing light east­er­ly winds. Last­ly, there were oro­graph­ic ef­fects, where hilly ter­rain like the North­ern Range fun­nels moist air up­s­lope in­to a de­vel­op­ing thun­der­storm.

What made this event par­tic­u­lar­ly se­vere is that winds high­er in the at­mos­phere that move these show­ers and thun­der­storms were al­so light, mean­ing any show­ers or thun­der­storms that de­vel­oped re­mained sta­tion­ary with pre­cip­i­ta­tion ac­cu­mu­lat­ing in a small area.

Be­tween Care­nage and Port-of-Spain, up to 75 mil­lime­tres of rain­fall was record­ed be­tween 2.30 pm and 4.30 pm and rain­fall rates were in ex­cess of 100 mil­lime­tres per hour.

This amount of rain with­in two hours in any area would trig­ger se­vere floods, re­gard­less of the ter­rain. How­ev­er, cli­mate change may play a role in this ex­treme rain­fall and sub­se­quent flood­ing events.

The T&T Me­te­o­ro­log­i­cal Ser­vice has not­ed over the last 40 years that while over­all av­er­age rain­fall has de­creased, in­tense sin­gle-day rain­fall events have steadi­ly in­creased.

In fact, six of the top ten years that had sin­gle-day high­est rain­fall events have oc­curred since 1990. From 1980 to present, there have been in­creas­es in sin­gle-day ex­treme rain­fall days and an in­crease in three-day max­i­mum rain­fall to­tals.

These lat­ter two rain­fall event clas­si­fi­ca­tions pro­duce high-im­pact flood events.