Lake Kariba wa­ter level ex­pected to im­prove

Chronicle (Zimbabwe) - - National News/feature - Sife­lani Tsiko

Wa­ter lev­els in Lake Kariba which had dropped for the first time in more than half a cen­tury since the reser­voir was com­mis­sioned to gen­er­ate power in the 1950s, are ex­pected to im­prove sig­nif­i­cantly af­ter cli­mate ex­perts fore­cast that Zim­babwe and Zam­bia will re­ceive good rains in the 2016–2017 crop­ping sea­son.

How­ever, wa­ter ex­perts cau­tion full re­cov­ery will not be im­me­di­ate and will re­quire at least three years with suf­fi­cient rains.

Zam­bezi River Author­ity chief ex­ec­u­tive of­fi­cer, En­gi­neer Mun­yaradzi Mun­odawafa, told the Zim­pa­pers Syn­di­ca­tion Ser­vices that the good rain­fall fore­cast for the ap­proach­ing sea­son of­fers a glim­mer of hope for wa­ter in­flows into Lake Kariba which gen­er­ates power for Zim­babwe and Zam­bia and sup­ports liveli­hoods in eight Sadc ri­par­ian states.

“The lat­est rain­fall fore­cast is quite pos­i­tive in­deed, but wa­ter for gen­er­a­tion is very scarce and as a re­sult even if we get above nor­mal rain­fall, wa­ter re­cov­ery at the lake will not be im­me­di­ate,” said Eng Mun­odawafa.

Lake Kariba, the world’s big­gest man made reser­voir, holds around 19 bil­lion cu­bic me­tres of gen­er­a­tion wa­ter com­pared to the full ca­pac­ity of 65 bil­lion cu­bic me­tres. The lake is ap­prox­i­mately 29 per­cent full. “The es­ti­mated time needed for re­cov­ery is up to three years,” Eng Mun­odawafa said.

The Me­te­o­ro­log­i­cal Ser­vices Depart­ment is­sued out the na­tional fore­cast re­cently which showed that dur­ing the ap­proach­ing rainy sea­son, which is ex­pected to start this month, Zim­babwe will re­ceive nor­mal to above nor­mal rains bring­ing re­lief to the coun­try which has been crav­ing for some good rain­fall ac­tiv­ity af­ter it was rav­aged by one of the worst droughts in decades.

Cli­mate ex­perts say there is a high like­li­hood of an early start of the sea­son for the whole coun­try.

In the first half of the sea­son (Oc­to­ber–De­cem­ber 2016) Re­gion 1 which cov­ers Harare, much of Mashona­land East, Mashona­land West , Mashona­land Cen­tral, north­east­ern parts of Mid­lands, parts Man­i­ca­land and Re­gion 2 which in­cludes the bulk of Mata­bele­land North, parts of Mid­lands and parts of Mashona­land West are likely to re­ceive nor­mal to above nor­mal rain­fall.

In the same pe­riod, the most rain deficit pocket of the coun­try - Re­gion 3 which cov­ers Masvingo, the bulk of Mid­lands, the ex­treme south­ern parts of Man­i­ca­land and the bulk of Mata­bele­land South is also ex­pected to get nor­mal to above nor­mal rain­fall.

Good rains are also ex­pected to per­sist in Re­gion 1 and 2 in the Jan­uary to March 2017 sea­son while Re­gion 3 is ex­pected to get nor­mal to be­low nor­mal rains in the same pe­riod.

Im­proved rain­fall fore­cast in parts of An­gola and Zam­bia in the com­ing sea­son are also ex­pected to in­crease Kariba Dam wa­ter lev­els.

The Zam­bezi River Author­ity says at least 18 per­cent of the wa­ter that flows into Lake Kariba comes from An­gola and the western part of Zam­bia, par­tic­u­larly the Lukulu area.

Lake Kariba strad­dles Zim­babwe’s bor­der with Zam­bia, generating hy­dropower for both south­ern African coun­tries, but fall­ing wa­ter lev­els have forced the two na­tions to cut power pro­duc­tion.

A drought which rav­aged Zim­babwe and Zam­bia in­clud­ing most other Sadc coun­tries in the 20152016 sea­son, forced the two coun­tries to in­tro­duce a pun­ish­ing load-shed­ding sched­ule for con­sumers.

Be­fore power im­ports in­creased, Zim­bab­wean con­sumers used to go for an av­er­age of 18 hours with­out elec­tric­ity due to re­duced wa­ter lev­els at Kariba which led to the Zam­bezi River Author­ity (ZRA) forc­ing the Zim­babwe Power Com­pany and Zesco (Zam­bian) to re­duce generating ca­pac­ity at the Kariba Power Sta­tion.

When wa­ter lev­els dropped sharply, ZRA forced the two util­i­ties to re­duce power gen­er­a­tion to a com­bined 550MW.

ZRA has al­lo­cated an av­er­age of 20 bil­lion cu­bic me­tres to Kariba South and Kariba North power sta­tions from Lake Kariba for 2016 which the two coun­tries are shar­ing equally.

The author­ity is strictly mon­i­tor­ing the two power util­i­ties to con­tinue to ad­here to the 550 MW com­bined gen­er­a­tion to sus­tain the wa­ter avail­able un­til the next rainy sea­son.

By July, the two sta­tions run by the two coun­tries were each given 3,08 bil­lion cu­bic me­tres and 1,58 bil­lion cu­bic me­tres re­spec­tively, of wa­ter to be utilised in the re­main­ing five months to year end, ac­cord­ing to a re­port sub­mit­ted to the Zim­babwe fi­nance min­istry.

“It is there­fore clear that con­tin­ued over-util­i­sa­tion of wa­ter by both power sta­tions will neg­a­tively im­pact on the vol­ume of stored wa­ter at the end of the year,” said Fi­nance and Eco­nomic De­vel­op­ment Min­is­ter, Pa­trick Chi­na­masa, in his re­cent mid-term fis­cal pol­icy re­view state­ment.

“De­pend­ing on the rain­fall to be re­ceived in 2017, this may also sub­se­quently im­pact on the vol­ume of wa­ter avail­able for power gen­er­a­tion in 2017. Given the un­cer­tain­ties of long term cli­mate fore­casts, it is crit­i­cal that sus­tain­able util­i­sa­tion of wa­ter at Lake Kariba is pri­ori­tised to en­sure the reser­voir level at the end of each year is not worse off than it was in the pre­ced­ing year.”

ZRA said hy­dro­log­i­cal sim­u­la­tions which had been done show that it will take three or more years for Lake Kariba to re­cover to its nor­mal lev­els.

Said Uni­ver­sity of Zim­babwe hy­drol­o­gist Dr Hod­son Makurira: “You can’t re­ally tell whether Lake Kariba is likely to re­cover soon or not based on the good rain­fall fore­cast. There are no easy an­swers. The link­ages be­tween a good rain­fall fore­cast and wa­ter in­flows into the lake are com­plex and prob­a­bilis­tic.

“Even if we have good rains, it’s highly un­likely that it will fill up. It takes sev­eral good rain­fall sea­sons to get it to fill up.”

The UZ wa­ter ex­pert said a bet­ter hy­dro­log­i­cal fore­cast for the lake could only be given based on in­flows ob­served at var­i­ous points along the Zam­bezi River.

“Based on ob­ser­va­tion, you are likely to make in­formed de­ci­sions rather than bas­ing our fore­cast on the rain­fall for one sea­son,” said Dr Makurira.

“It’s like a bath tub – it de­pends on what gets in and what gets out through the drain plug. If the plug is too big and is let­ting out more wa­ter, then it will take time for the tub to be filled with wa­ter.

“So it de­pends much on the de­mand and sup­ply of wa­ter. This is a pre­dic­tion (rain­fall fore­cast) and things can go wrong like it has hap­pened in the past. We can only gen­er­ate an­swers when we ob­serve in­flows from north-western Zam­bia where the river rises.”

To en­sure, bet­ter re­cov­ery of the wa­ter lev­els in the lake, Dr Makurira said there is a need to strike a bal­ance be­tween de­mand and wa­ter stor­age as well as safety for the dam in­fra­struc­ture.

“We can do sim­u­la­tions but ob­ser­va­tion is crit­i­cal,” the UZ wa­ter ex­pert said. “Af­ter a se­vere drought, very few dams can store and fill up with wa­ter. It takes two to three years with good rains.”

Dr Makurira said it was vi­tal for ZRA to con­tin­u­ously mon­i­tor the us­age of wa­ter by the two power util­i­ties to al­low for the lake to build up its wa­ter lev­els.

The ZRA says it is con­tin­u­ously mon­i­tor­ing, re­view­ing and in­form­ing the two util­i­ties on the avail­abil­ity of wa­ter for power gen­er­a­tion at Lake Kariba so that the power util­i­ties can ad­just their op­er­a­tions to al­low for con­tin­ued avail­abil­ity of wa­ter.

The wa­ter author­ity says power gen­er­a­tion was at 12 per­cent com­pared to 65 per­cent when wa­ter lev­els were high.

The Zam­bezi River which rises in black marshy dambo and dense un­du­lat­ing miombo wood­lands in the Ike­lenge district in the North-Western Prov­ince of

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