Water, Sewage & Effluent September October 2018 | Page 39

The combination of significant population
growth, limited government resources,
and corruption undermining infrastructure
investments, the misallocation of water —
plus an unprecedented three-year drought
— have all contributed to the water crisis.
Tony Wong from Australia, as one of
the keynote speakers, introduced the
concept of “Water-sensitive Cities”.
Australian cities, like their South
African counterparts, were historically
dependent on one single water source,
whilst its own dams were spilling. In
short, it boils down to this: Welbedacht
Dam, as the largest dam supplying
Mangaung, is 95% silted up and
therefore water has to be pumped to
an off-channel dam (Knelpoort) as well
as to Rustfontein Dam.
The logical operating rule for any
off-channel storage — as also found
in other Free State towns such as
Kroonstad and Lindley — is maximum
pumping to the off-channel storage
whilst the river is flowing. Due to
operational problems at the pump
station owed by DWS, only nine-
million cubic metres were pumped
in 2012/13 instead of 29-million and
only 20% of the planned volume in the
following year.
This resulted in the Rustfontein
Dam dropping to 17% with severe
water restrictions being enforced. In
the meantime, smaller dams owned
by the Mangaung metro had started
overflowing,
whilst
restrictions
remained in place. This is a perfect
example where bad operating rules
and lack of maintenance had caused
an artificial drought.
A last sobering thought on Cape
Town and Mangaung is that the short-
term pain will hopefully be part of the
long-term process to eventual greater
sustainability of our water supplies.
Reference: A perfect storm: The
hydropolitics of Cape Town’s water
crisis. Report by Amy Fallon, published
by Global Water Forum. April 2018. u
Samantha Yates – secretary
general of the Global Water
Leaders Group
namely surface dams fed by run-off.
Even if this means a series of dams
like Cape Town or a complex system
of water transfers like Gauteng, such
cities still depend on one type of
source, and that is rainfall. That makes
our water supply extremely vulnerable.
So, when droughts “sneak up on you”,
there will be major problems.
The way the rain comes is also
important. In the 1980s, the Vaal Dam
catchment experienced a ‘green
drought’ — soft rain that is good for
green pastures but little run-off in
the streams. Similarly, an Australian
catchment had, in a single season, a
20% reduction in rainfall, resulting in a
substantial 60% loss in run-off.
Large
cities
are
especially
vulnerable. The lesson from Australia
as well as from Cape Town is that any
city or area must plan and manage a
portfolio of water sources. That is,
investing in a more diversified water
supply, such as underground sources,
desalination, and water re-use.
An example is the water plan for the
state of Victoria that includes seawater
desalination, water recycling, and
urban stormwater harvesting. Water
planners should ask: “What is the best
water mix for our urban water supply?”
A water-sensitive city must be on top
of not only its water supply but also
sewers and wastewater re-use, its
drainage channels and stormwater,
and indeed the total water cycle.
Apart from creating infrastructure,
the importance of management was
highlighted in several sessions and
workshops at the conference.
An interesting one was a case
study on Mangaung Metro, where the
municipality was forced to implement
water restrictions in Bloemfontein
innovations
‘What the Cape Town crisis
shows is that preparing for
drought requires a team
effort — evidence-based
science, pressure from the
public, and political will.’
Figure 1: The perfect storm.
Helgard Muller is a regular
contributor to Water, Sewage &
Effluent (WSE). His vast knowledge
in policy and regulations while
at the Department of Water and
Sanitation adds huge value to WSE.
Source: Amy Fallon, Global Water Leaders Group
Water Sewage & Effluent September/October 2018
37
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