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dam-l Water demand management submission/LS
Submission to WCD Cairo hearings made last week.
Submitted by Wildlife and Environment Society of South Africa, KwaZulu-Natal
Region and Earthlife Africa Durban.
WATER DEMAND MANAGEMENT IN THE MGENI RIVER CATCHMENT - KWAZULU NATAL
INTRODUCTION
In November 1999 the Environmental Monitoring Group (EMG); Group for
Environmental Monitoring (GEM) and the International Rivers Network (IRN -
Botswana) will be hosting the first Southern African Hearings for
Communities Affected by Large Dams. This event will be held in Cape Town.
Two of the key objectives of the two day meeting are to highlight issues of
concern in the region regarding large dams and to facilitate improved
communication between those people who have been affected in the past and
those who may be affected in the future by the construction and operation of
new dams. The recordings of these hearings will form part of the independent
assessment of the world’s large dams being undertaken by the World
Commission on Dams (WCD). The WCD’s secretariat is based in Cape Town.
The Department of Water Affairs and Forestry (DWAF) recently released their
"Water Conservation and Demand Management National Strategy Framework". In
response to this initiative and the actions agreed to at a recent meeting
with affected communities in the province, Earthlife Africa (Durban) and the
Wildlife and Environment Society of South Africa (WESSA) have decided to
submit this article on the water demand strategy presently being developed
for the Mgeni River catchment. This document will form part of the
KwaZulu-Natal submission to the hearings in Cape Town.
THE MGENI RIVER CATCHMENT
The Mgeni River rises at an altitude of 1 900 m above mean sea level, 60 km
west of Pietermaritzburg and 15 km north west of Impendle in the Natal
Midlands. The 255 km river drains a catchment area of 4 441 km2, which
generates an estimated mean annual runoff of 671million m3. The major
tributaries of the Mgeni are the Lions, Karkloof and Msunduzi rivers.
The first impoundment on the Mgeni is Midmar dam with a storage capacity of
177 million m3. Downstream of Howick and the confluence of the Karkloof
River and the Mgeni lies the second impoundment, Albert Falls dam with a
capacity of 290 million m3. The third dam on the river is Nagle with 25
million m3 storage capacity. This is followed by Inanda dam with a storage
capacity of 252 million m3. The Mgeni enters the sea 33 km downstream of
Inanda dam at a point 5 km north of Durban City centre.
In addition to the four impoundments on the Mgeni, Henley Dam on the
Msunduzi River (tributary to the Mgeni ) has a storage capacity of 1,5
million m3. The combined firm yield of the four dams on the Mgeni River is
estimated to be 310 million m3 per annum. Of this 18 million m3 per annum
have been reserved for the water requirements of the estuary. This yield is
supplemented by the Mooi - Mgeni augmentation scheme 30 million m3 which
involves the transfer of water by pipeline from the Mooi River (part of the
Tugela River catchment) into the Mpofana River and on into the Lions River.
The Lions joins the Mgeni upstream of Midmar dam. The assured yield of the
five impoundments in the Mgeni River system presently just meets the current
domestic and industrial demand for the catchment.
Approximately 20 % of South Africa’s gross national product is generated
within the Mgeni River catchment and 65 % of the total economic production
of KwaZulu-Natal. The Mgeni is widely recognised as one of the most
important river systems in the country and certainly the most important
river in the province from an economic perspective.
The major land use activities in the Mgeni catchment are: commercial
livestock 25 %; cultivated crops 18 %; timber plantations 10 %; informal
peri-urban and rural settlements 25 %; formal urban areas 8 % with the
remainder being undeveloped or used for other purposes.
WATER DEMAND MANAGEMENT INITIATIVES
The Durban Metropolitan Council is Umgeni Water’s largest customer,
accounting for 82,3 % of annual sales in 1998/99. This equates to 212
million m3 for use by domestic consumers and 67 million m3 for commerce and
industry. During the period 1998/99 the average annual water demand increase
to Durban was less than 1 % per annum.
It is predicted that the total bulk water demand on the Mgeni River system
will increase from about 279 million m3 in 1998/99 to about 418 million m3
by 2025. 100 % of this increase is expected to be used by consumers in the
greater Durban area. As it is unlikely that other demands on the system will
increase significantly during this period, the provision of bulk water for
residential, commercial and industrial use will represent over two thirds of
all use from the Mgeni River catchment by 2025.
In order to meet the projected demands on the Mgeni River system, up to
2025, Umgeni Water completed a study in the mid 1990's that recommended the
following five development options:
Raise the Midmar dam wall;
Increase the diversion capacity of the Mooi - Mgeni transfer scheme;
Construct the Mearns dam on the Mooi River;
Construct the Spring Grove dam on the Mooi River;
Construct the new Smithfield dam on the Mkomazi.
However during the past two years Durban Metro Water Services have been
able, through the introduction of a stepped tariff payment system and water
loss management programme, to curb the Metro’s water demand to the 1997
level of use (279 million m3). In 1997 the Metro announced the introduction
of a rising block tariff. Under this system the first 6 m3 per month is
supplied free whereas any consumption in excess of 30 m3 per month is
charged at a higher than normal rate. In the case of industry the Metro is
looking at setting a cost reflective tariff where the consumption is within
predetermined norms and a punitive tariff where industry exceeds those
norms.
In order to keep water demand increases to zero per cent per annum the Metro
continues to focus on the conservation of water through the reduction of
water losses. Three years ago unaccounted for water averaged 42 %. This
figure has been reduced to 33 % (1999) with the 2000 target being 20 %. In
this way the Metro can still expand the water supply network to those
residents who until now have not enjoyed a supply of potable water, while
keeping the bulk water requirement at the 1997 level. The measures
introduced by Durban Metro have resulted in Umgeni Water delaying the
implementation of the water augmentation schemes mentioned above by five
years. While the raising of Midmar dam’s wall and Phase 1 of the Mooi -
Mgeni transfer are likely to go ahead, so as to bring the assurance of
supply to within the acceptable limit of 98 %, the water demand for the
Mgeni system will be closely monitored before a decision is made to
construct any new dams on the Mooi and Mkomazi rivers.
A third strategy to reduce water demand would be water recycling. This has
not been seriously attempted; Durban Metro sells a limited amount of
semi-purified waste water to a few industrial clients, but the vast majority
of its waste water is pumped out to sea after preliminary treatment.
Suggestions by environmental organisations that domestic and industrial
effluent be treated seperately (as domestic effluent is more easily
recycled) have been ignored; It appears that fast and cheap effluent
disposal is supposed to be an attraction for industry.
However, given that co-disposal of different types of waste is contrary to
the new national environmental policy, and given that civil society is
empowered to resist negative environmental impacts by new legislation
(National Environmental Management Act), it is likely or at least possible
that water recycling might move up on the Agenda of Local Governments. This
could do away with or postpone new supply projects.
Acknowledgments
We would like to thank Messrs Mnguni, Gillham and Akerman from Corporate
Services, Umgeni Water and Mr N Macleod, Metro Water Services for their
assistance in providing information for this paper.
Prepared by:
Richard Hunt and Bryan Ashe
Committee members
WESSA Conservation Committee
Durban
South Africa
Richard Hunt
huntrp@iafrica.com
Bryan Ashe
bryan@mweb.co.za
3 November 1999
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Lori Pottinger, Director, Southern Africa Program,
and Editor, World Rivers Review
International Rivers Network
1847 Berkeley Way, Berkeley, California 94703, USA
Tel. (510) 848 1155 Fax (510) 848 1008
http://www.irn.org
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