CASE STUDY ON THE TOKWE MUKOSI DISASTER

BY

JONATHAN D. CHIFUNA

METEOROLOGICAL

SERVICES DEPARTMENT,

ZIMBABWE

BACKGROUND:

DAM CONTSTRUCTION STARTED IN THE 1980S

PEOPLE WERE TO BE RESETTLED BEFORE FILLING UP OF THE DAM

TO BE THE LARGEST INLAND WATERBODY IN ZIM

CONSTRUCTION DELAYS

THE AREA IS ONE OF THOSE ASSOCIATED WITH LOW ANNUAL RAINFALLS IN THE

COUNTRY

BACKGROUND:

REPORTS OF HEAVY RAIN IN THE PREVIOUS WEEKS

PEOPLE BEING MAROONED AND HOMES BEING SUBMERGED

WARNINGS HAD BEEN ISSUED

AS A RESULT A FACT FINDING MISSION SENT IN TO INVASTIGATE

METHODS USED:

• LOOKING AT THE SYNOPTIC SITUATION

• EYE OBSERVATIONS

• INTERVIEWS WITH PEOPLE ON THE GROUND

RUNDE CATCHMENT AREA:

TC. DELIWE

992 hpa

SSW 12KT

FRIDAY 17 NOVEMBER 2013

ACCUMULATED RAINFALL FOR NOVEMBER 2013

RUNDE CATCHMENT AREA

ACCUMULATED RAIN

FALL FOR THE MONTH IN

mm.

PERCENTAGE OF NORMAL FOR NOV 2013

Banket

Beitbridge

Binga

Buffalo Range

Buhera

Bulawayo Goetz

Chimanimani

Chinhoyi

Chipinge

Chisengu

Chisumbanje

Chivhu

Gokwe

Guruve

Gweru

Harare Bvdre Henderson

Hwange Npk

Kadoma

Kanyemba

Kariba

Karoi

Kezi

Kwekwe Lupane

Makoholi

Marondera

Masvingo

Matopos

Mhondoro

Mt Darwin

Mukandi

Mutare

Mutoko

Mvurwi

Nkayi

Nyanga

Plumtree Rupike

Rusape

Tsholotsho

Victoria Falls

Wedza

West Nich

Zaka Zvishavane

0

75

125

400

Percentage of normal for November 2013

21 DECEMBER 2013

POSITION OF THE LOW ASSOCIATED WITH THE ITCZ WHICH CAUSED A LOT OF PRECIPITATION OVER SOUTHERN AFRICA FROM 21 DECEMBER, 2013 UP TO THE TIME WHEN REPORT WAS WRITTEN 8 FEB 2014

30 DECEMBER 2013 06:00Z

REASON FOR HEAVY RAINS

AREA AFFECTED BY

FLOODING

(“EXCESSIVE

WATER”):

PROJECTED PRECIPITATIONFOR 31 DECEMBER2013

ACCUMULATED RAINFALL FOR DECEMBER 2013

RUNDE CATCHMENT AREA

ACCUMULATED RAIN

FALL FOR THE MONTH IN

mm.

PERCENTAGE OF NORMAL FOR DEC 2013

Banket

Beitbridge

Binga

Buffalo Range

Buhera

Bulawayo Goetz

Chimanimani

Chinhoyi

Chipinge

Chisengu

Chisumbanje

Chivhu

Gokwe

Guruve

Gweru

Harare Bvdre Henderson

Hwange Npk

Kadoma

Kanyemba

Kariba

Karoi

Kezi

Kwekwe Lupane

Makoholi

Marondera

Masvingo

Matopos

Mhondoro

Mt Darwin

Mukandi

Mutare

Mutoko

Mvurwi

Nkayi

Nyanga

Plumtree Rupike

Rusape

Tsholotsho

Victoria Falls

Wedza

West Nich

Zaka Zvishavane

0

75

125

400

Percentage of normal for December 2013

MONTH AVERAGE RAINFALL LONG TERM MEAN

RAINFALL AS A

PERCENTAGE OF

NORMAL

OCTOBER 21.0 26.2 80

NOVEMBER 70.9 79.1 90

DECEMBER

159.6 133.5 120

OND 251.6 238.8 105

ACUMMULATED RAIN AND % OF NORMAL FOR JAN

Kb

VF

Mu

BB

Bu Ch

Cz

Gk

Gw

Ha

Hw

Mv

MD

0

50

100

200

300

400

500

800

1000

Accumulated Rainfall for January 2013/14

Banket

Beitbridge

Binga

Buffalo Range

Buhera

Bulawayo Goetz

Chimanimani

Chinhoyi

Chipinge

Chisengu

Chisumbanje

Chivhu

Gokwe

Guruve

Gweru

Harare Bvdre Henderson

Hwange Npk

Kadoma

Kanyemba

Kariba

Karoi

Kezi

Kwekwe Lupane

Makoholi

Marondera

Masvingo

Matopos

Mhondoro

Mt Darwin

Mukandi

Mutare

Mutoko

Mvurwi

Nkayi

Nyanga

Plumtree Rupike

Rusape

Tsholotsho

Victoria Falls

Wedza

West Nich

Zaka Zvishavane

0

75

125

400

Percentage of normal for January 2014

ACUMMULATED RAIN AND % OF NORMAL FOR FEB

Banket

Beitbridge

Binga

Buffalo Range

Buhera

Bulawayo Goetz

Chimanimani

Chinhoyi

Chipinge

Chisengu

Chisumbanje

Chivhu

Gokwe

Guruve

Gweru

Harare Bvdre Henderson

Hwange Npk

Kadoma

Kanyemba

Kariba

Karoi

Kezi

Kwekwe Lupane

Makoholi

Marondera

Masvingo

Matopos

Mhondoro

Mt Darwin

Mukandi

Mutare

Mutoko

Mvurwi

Nkayi

Nyanga

Plumtree Rupike

Rusape

Tsholotsho

Victoria Falls

Wedza

West Nich

Zaka Zvishavane

0

75

125

400

Perecntage of normal for February 2014

OBSERVATIONS:

NGEZI RIVER

JUST BEFORE

MASVINGO

SINK HOLE ON THE ROAD

OBSERVATIONS:

PROVINCIAL

ADM MASVINGO

CPU GUTU

IN THE FIELD

EFFECTS:

299 HOMESTEADS WERE CURRENTLY BEING MOVED

+/- 50 VILLAGES AFFECTED

+/- 750 HOMESTEADS MOVED

26 VILLAGES SUBMERGED - TSVIYO VILLAGE PARTIALLY

SUBMERGED WATER CONTINUES TO RISE

PEOPLE FROM WITHIN 2 KM OF THE DAM MOVED AWAY

POLICE ON THE GROUND ON OUTREACH PROGRAMMES

EFFECTS:

CHOPPER LIFTING STRANDED PEOPLE

A TOTAL OF 3500 HOMESTEADS WERE EARMARKED FOR

RESSETTLEMENT

THROWBACK OF 100m EXPECTED IN A DAY WITH A RISE OF 30cm.

AT PEAK WATER WAS RISING AT THR RATE OF 1 TO 1.5m A DAY

FOR THREE DAYS.

OBSERVATIONS:

AT THE DAM WALL:

BREACHED LOWER PART THE TOKWE MUKOSI DAM WALL.

DOWNSTREAM OF THE TOKWE MUKOSI THE TUGWE RIVER IN FLOOD BUT THEY SAY IT IS NORMAL FOR THIS TIME OF THE YEAR.

TAKEN FROM THE DAM WALL.

ONE OF THE TWO SAFETY VALVES NOT OPEN AS THE ENGINEERS SAY THAT IT IS NOT YET NECESSARY.

MARCH 2ND 2014 AT 15:15 B

ZAKA 82mm

MAKOHOLI 63mm

MASVINGO 53mm

3rd MARCH

T-Mukosi 65mm

CONCLUSION:

Flooding of the Tokwe Mukosi is not out of the unusual. In building the dam,

this should have anticipated. This has happened elsewhere in the past

in this country.

The displacement of the unfortunate people was a combination social,

financial, planning issues etc.

People should have been moved before or soon after dam construction started

.

Although the public were aware of the warnings issued by the Met Office there

was nothing they could do.

The excessive rains were caused by a deep low associated with the Inter

Tropical Convergence Zone (ITCZ) that has been situated over

Botswana from 21 December 2013.