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Telephone: 012-336-7860
Reference: 2/1/5/1
MINISTER OF WATER AND ENVIRONMENTAL AFFAIRS
NATIONAL ASSEMBLY: QUESTION 160 FOR WRITTEN REPLY
A draft reply to the above-mentioned question asked by Mr M J Ellis (DA);
is attached for your consideration.
ACTING DIRECTOR-GENERAL
DATE:
DRAFT REPLY APPROVED/AMENDED
MRS B E E MOLEWA, MP
MINISTER OF WATER AND ENVIRONMENTAL AFFAIRS
DATE:
NATIONAL ASSEMBLY
FOR WRITTEN REPLY
QUESTION NO 160
DATE OF PUBLICATION IN INTERNAL QUESTION PAPER: 10 FEBRUARY 2011
(INTERNAL QUESTION PAPER NO. 01)
160. Mr M J Ellis (DA) to ask the Minister of Water and Environmental
Affairs:
(1) (a) What policies inform the management of percentage capacity
of dams and (b) when were these policies implemented;
(2) whether there have been any changes in policies that govern the
management of the percentage capacity of dams since 1 January
2008 in order to actively condone exceeding capacity for the
purposes of storing more water; if not, why not; if so, what are
the relevant details;
(3) hether she will review the policies that govern the management
of the percentage capacity of dams in light of the (a) recent
floods and (b) likelihood that under the impacts of future
climate change the frequency and intensity of floods is
predicted to increase; if not; why not; if so, when;
(4) whether she will institute an inquiry into the management of the
Vaal Dam during the recent floods; if not, why not; if so, what
are the relevant details;
(5) whether her department has learnt any lessons from the
management of the Vaal Dam during the recent floods that will
inform future management practices; if not, why not; if so, what
are the relevant details?
NW173E
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REPLY:
(1)(a) The management of water storage is not informed by any
policy but by operating rules that are specific for each dam.
These operating rules govern how much water must be stored or
released taking into account the water allocation requirements
and flooding risks.
(1)(b) The implementation of operating rules is a
continuous process that depends on the hydrological conditions
in the catchment.
(2) There has been no change in the approach to dam operation.
Instead, operating rules are reviewed in line with hydrological
and development trends in the catchment. However, the operations
aim to ensure that at the end of the rainy season, the dams
should be storing possible maximum volume of water.
(3)(a) The Department is continuously reviewing operating
rules depending largely on the hydrological conditions/events in
the catchment - like future climate change.
(3)(b) The dam operating rules are specific for each and
are reviewed in line with development trends, frequency and
intensity of floods and drought in the specific catchment.
4) There is no need for the inquiry since these were only floods of
a medium magnitude which were handled quite adequately by the
flood management team. All outflow peaks were less than the
inflow peaks and the recurrence period of the highest Vaal Dam
inflow peak was less than 20-years.
-2-
The Vaal Dam outflow peak of 2400 m3/s was only 80% of the
inflow peak.
(5) Yes, the Department has been communicating effectively
during the recent floods to those affected and farmers and
blomhof areas NC areas, who met during the floods also
volunterly infomed me in a meeting that they were receiving
adequeate and information. We do continue to lear as we listen
to any further matter or innovation raised subject to
hydrological scientifically determined as refer to above.
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