110127 floods

7/28/2019 110127 Floods

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Presentation to the Portfolio Committee:

Water & Environment

Management of Floods / Disaster

Presentation by

Mr L Z Maswuma

Director: Hydrological Services

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PART I

Update on recent floods in the Country

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OVERVIEW OF THE FLOOD MANAGEMENT IN

RSA (1)

• RSA is a semi-arid country and rainfall is spread

unevenly – floods & drought predominately.

• This presentation is limited to recent flood

situation in the country

• The Department’s Regional Offices assume

responsibility for the management of localised

floods

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OVERVIEW OF THE FLOOD MANAGEMENT IN

RSA (2).• National Office is responsible for flood

management of the Vaal and Orange RiverSystem covers Gauteng, FS, NW & NC.ThisSystem comprises 49% of the total area of RSA.

• The National office also monitors andcoordinate information on floods occurring onother river systems that impact toneighbouring countries – Moz & Namibia.

• These river systems include Inkomati, Limpopoand Olifants

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AREAS AFFECTED BY FLOODS (1)

KwaZulu Natal

5

Municipality &

Specific Area

Impact on water

supply

Proposed

Intervention &

estimate costs

uThukela District

Municipality

•Bergville

submerged the

water abstraction

pumping station

Tankering & an

est.cost R900 000

is required

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North West

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Municipality &

Specific Area

Impact on water

supply

Proposed

Intervention &

estimate costs

Lekwa TeemaneLocal Municipality

submerged thewater abstraction

pumping station

Alternate sourceidentified & is

being used

Water bornediseases reported Fundingrequirement not

yet quantified for

health & hygiene

campaigns

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Free State

7

Municipality &

Specific Area

Impact on water

supply

Proposed

Intervention &

estimate costs

Dihlabeng LocalMunicipality

•Fouriesburg

•Bethlehem

•Rosendal

•Clarens

Loose pumps andmotors washed

away

Funding isrequired to repair

pumps and

estimate cost is

R1.5 mil

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Free State

8

Municipality &

Specific Area

Impact on water

supply

Proposed

Intervention &

estimate costs

Moqhaka LocalMunicipality

•Kroonstad

•Viljoenskroon

•Steynsrus

Raw water pumpstation flooded

and water

infrastruture

damaged

Not yetquantified,

funding is

required

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Free State

9

Municipality &

Specific Area

Impact on water

supply

Proposed

Intervention &

estimate costs

Nala LocalMunicipality

•Monyakeng and

Wesselsbrontake-off points

Raw water pumpstation flooded

and water

infrastruture

damaged

Not yetquantified,

funding is

required

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Free State

10

Municipality &

Specific Area

Impact on water

supply

Proposed

Intervention &

estimate costs

Nala Local

Municipality

•Wepener

•Dewetsdorp

pump station

blocked and also

overflowing, this

also affected thetreatment plant

Damage not yet

quantified,

funding is

required

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Limpopo

11

Municipality &

Specific Area

Impact on water

supply

Proposed

Intervention &

estimate costs

Capricon DM

Vhembe DM

Waterberg DM

Mopani DM

Sekhukhune DM

Historically,

affected by

cholera outbreaks

that usuallyfollow the flood

season are

managed.

Community

awareness

campaigns;

Cholera packs &Potable

treatment plants

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Mpumalanga & Northern Cape• Floods causes major damages

• Water levels are still very high in most cases

and assessment work on damages is ongoing

Important: Eastern Cape and Western Cape

Major concern is drought

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CURRENT SITUATION (1)

We do daily update on the situation at the four largedams in the Vaal Orange River system. Below is theupdate as at 26 January 2011 @ 14h00 and newreport has been issued this morning and will be

updated today at 14h00

Vaal Dam:

Vaal Dam capacity is currently at 100%

The current inflow is 1200 m3/s with an outflow of 680 m3/swith six (6 ) gates open

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Bloemhof Dam:

Bloemhof Dam capacity is currently at 92%

The current inflow is 1200 m3/s (to increase to 1800m3/s on 2011/01/29) and the outflow is 1300 m3/s

Gariep Dam:

Gariep Dam is currently at 115% (to increase to 123%on 2011/01/29).

The inflow is 4200 m3/s (to increase to 5000 m3/s on2011/01/27) and the outflow is 2100 m3/s (toincrease to 3200 m3/s on 2011/01/29).

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Vanderkloof Dam:

Vanderkloof Dam capacity is currently at 110% (toincrease to 116% on 2011/01/31)

The inflow is 2100 m3/s (to increase to 3200 m3/s on2011/01/30) and the outflow is 1700 m3/s (toincrease to 3000 m3/s on 2011/01/31).

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Lower Orange River

Predicted high flow at Upington of 4500 m3/s (stage7.3m (0.5m lower than the flood earlier this month))on 2011/02/03

A flow of 4500 m3/s is forecasted for the Lower OrangeRiver. The high discharge is mainly from the OrangeRiver.

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Limpopo, Olifants and Inkomati River Systems

Water levels are table and expected to rise as wetaherservices forecasted 60% chance rainfall – catchmentsare very wet and high flows are expected.

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uThugela, Umgeni, Hluhluwe river systems

Water levels are table and the uThugela river isexpected to rise as weather services forecasted morethan 30% chance of rainfall – catchments are very

wet and high floors are expected.

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uMsundusi and Fish river systems

Water levels are normal and may rise as more rains areexpected.

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CONCLUSIONS (1)

• Minister issued a press statement on how we areresponding on Disaster and has put aside R20million

for repairing of water resources infrastructure

• Assessment of damages is still continuing whilst river

levels are lowering

• Department is a member of the NATJOC and is

providing info on daily river flow levels and weekly

state of dams. The information is also accessible bypublic on internet

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CONCLUSIONS (2)

• Disaster management strategy which includemanagement of hydrological risks and extremes isbeing finalised and it is informed by National DisasterManagement Act -

• River levels in the Inkomati, Olifants, Thugela andLimpopo River systems are lowering

• Orange river levels are rising and it pose risks in thelower orange – Gariep and Vanderkloof dams have

no flood gates hence overflow can not be manuallycontrolled to keep more water in the dams

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CONCLUSIONS (3)

• More rainfall I still expected in most parts of the country towards March 2011

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PART 2

Flood management in the Vaal-River

System

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INTRODUCTION (1)

Management of extreme floods in the Vaal /Orange River system is an event drivenactivity done by the Department of Water Affairsin consultation with SAWS on daily weather Information and COGTA (NDMC).

The “Flood Room” in Pretoria serves as an

information centre to collect, process anddistribute rainfall, stage and flow data

Information is then sent through to NDMC – dailyand other institutions in the

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INTRODUCTION (2)

The main objectives of flood management is to:• protect the life of people and minimisation of

infrastructure damages

• Ensuring that the dams are 100% full at theend of the flood

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Vaal / Orange River System

Vaal- Orange System is about 49% the size of South Africa, excluding Lesotho

VAAL- ORANGE RIVER SYSTEM

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MONITORING STATION IN THE VAAL-ORANGE

RIVER SYSTEM

50 Gauging stations collecting near real time flow and / or rainfalldata - available on the Hydrology real time Web Site

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VAAL- ORANGE RIVER SYSTEM MODELLING

Rainfall runoff, flood routing and dam optimisation

models are used to operate Vaal Dam. Aim to

minimise the flow in the system and to get rid of

excess water in the system as soon as possible

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ROUTING TIMES IN VAAL- ORANGE SYSTEM

Flood warnings can provide time for people to take

action to protect their property as well as allowingemergency services to prepare and plan for

evacuations and other emergency actions

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MANAGEMENT OF INFLOW/OUTFLOWS (1)Vaal Dam

0

500

1000

1500

2000

2500

3000

1 2 / 1 7 / 2 0

1 0

1 2 / 1 9 / 2 0

1 0

1 2 / 2 1 / 2 0

1 0

1 2 / 2 3 / 2 0

1 0

1 2 / 2 5 / 2 0

1 0

1 2 / 2 7 / 2 0

1 0

1 2 / 2 9 / 2 0

1 0

1 2 / 3 1 / 2 0

1 0

1 / 2 / 2 0

1 1

1 / 4 / 2 0

1 1

1 / 6 / 2 0

1 1

1 / 8 / 2 0

1 1

1 / 1 0 / 2 0 1

1

1 / 1 2 / 2 0 1

1

1 / 1 4 / 2 0 1

1

1 / 1 6 / 2 0 1

1

1 / 1 8 / 2 0 1

1

1 / 2 0

/ 2 0 1

1

1 / 2 2

/ 2 0 1

1

1 / 2 4

/ 2 0 1

1

Date

D i s c h a r g e

85

90

95

100

105

110

115

C a p a c i t y (

% )

Vaal Dam Inflow Vaal Dam Outflow Vaal Dam (%)

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MANAGEMENT OF INFLOW/OUTFLOWS (2)

Bloemhof Dam

0

500

1000

1500

2000

2500

3000

3500

4000

1 2 / 1 7 / 2 0

1 0

1 2 / 1 9 / 2 0

1 0

1 2 / 2 1 / 2 0

1 0

1 2 / 2 3 / 2 0

1 0

1 2 / 2 5 / 2 0

1 0

1 2 / 2 7 / 2 0

1 0

1 2 / 2 9 / 2 0

1 0

1 2 / 3 1 / 2 0

1 0

1 / 2 / 2 0

1 1

1 / 4 / 2 0

1 1

1 / 6 / 2 0

1 1

1 / 8 / 2 0

1 1

1 / 1 0 / 2 0 1

1

1 / 1 2 / 2 0 1

1

1 / 1 4 / 2 0 1

1

1 / 1 6 / 2 0 1

1

1 / 1 8 / 2 0 1

1

1 / 2 0

/ 2 0 1

1

1 / 2 2

/ 2 0 1

1

1 / 2 4

/ 2 0 1

1

Date

D i s c h a r g e

85

87

89

91

93

95

97

99

101

103

105

C a p a c i t y ( % )

Bloehof Inflow Bloemhof Outflow Bloemhof (%)

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MANAGEMENT OF INFLOW/OUTFLOWS

Gariep Dam

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1 2 / 1 7 / 2 0

1 0

1 2 / 1 9 / 2 0

1 0

1 2 / 2 1 / 2 0

1 0

1 2 / 2 3 / 2 0

1 0

1 2 / 2 5 / 2 0

1 0

1 2 / 2 7 / 2 0

1 0

1 2 / 2 9 / 2 0

1 0

1 2 / 3 1 / 2 0

1 0

1 / 2 / 2 0

1 1

1 / 4 / 2 0

1 1

1 / 6 / 2 0

1 1

1 / 8 / 2 0

1 1

1 / 1 0 / 2 0 1

1

1 / 1 2 / 2 0 1

1

1 / 1 4 / 2 0 1

1

1 / 1 6 / 2 0 1

1

1 / 1 8 / 2 0 1

1

1 / 2 0

/ 2 0 1

1

1 / 2 2

/ 2 0 1

1

1 / 2 4

/ 2 0 1

1

Date

D i s c h a r g e

85

90

95

100

105

110

115

120

125

C a p a c i t y ( % )

Gariep Inflow Gariep Outflow Gariep (%)

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MANAGEMENT OF INFLOW/OUTFLOWS (4)Vanderkloof Dam

0

500

1000

1500

2000

2500

3000

1 2 / 1 7 / 2 0

1 0

1 2 / 1 9 / 2 0

1 0

1 2 / 2 1 / 2 0

1 0

1 2 / 2 3 / 2 0

1 0

1 2 / 2 5 / 2 0

1 0

1 2 / 2 7 / 2 0

1 0

1 2 / 2 9 / 2 0

1 0

1 2 / 3 1 / 2 0

1 0

1 / 2 / 2 0

1 1

1 / 4 / 2 0

1 1

1 / 6 / 2 0

1 1

1 / 8 / 2 0

1 1

1 / 1 0

/ 2 0 1

1

1 / 1 2

/ 2 0 1

1

1 / 1 4

/ 2 0 1

1

1 / 1 6

/ 2 0 1

1

1 / 1 8

/ 2 0 1

1

1 / 2 0

/ 2 0 1

1

1 / 2 2

/ 2 0 1

1

1 / 2 4

/ 2 0 1

1

Date

D i s c h a r g e

85

90

95

100

105

110

115

C a p a c i t y ( %

)

vd Kloof Inflow vd Kloof Outflow vd Kloof (%)

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CONCLUSION (1)

In the recent floods almost double the volumeof Vaal Dam and four times the volume of

Bloemhof Dam flowed through the dams

Short, medium and long term weather

forecasts, satellite and radar images and 24

hour rainfall figures play a major role in

operating decisions during the flood

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CONCLUSION (2)

Apart from possible dam failure and loss of life,incorrect or poor dam operation could lead to

billions of Rands in flood damage. (Example:

the Zuikerbosch and Vereeniging pump

stations are insured for about R 2.4 billion andproperty along the river in Vereeniging for

about R 10.2 billion)

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THANK YOU

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110127 floods

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