Options To Increase the Water
Availability
SSC Meeting on 30 April 2013,
Bundu Lodge, Nelspruit
Options To Increase The Water Availability
1.
2.
3.
4.
5.
6.
7.
8.
9.
Removal of Invasive Alien Plants (IAPs)
Ground water development
System operating rules
Eliminating unlawful water use
Water reallocation
Dam construction
Water resource classification
Rainwater and fog harvesting
Water reuse
Options To Increase The Water Availability
Removal Of IAPs
• Estimated infested area in Kwena Dam catchment - 77 km2
• Estimated infested area in Primkop Dam catchment – 18 km2
• Focus should firstly be on riparian zones.
Options To Increase The Water Availability
Removal Of IAPs
Catchment
Stream flow
Reduction
million m3/a
Estimated yield
increase due to
Removal of IAPs
million m3/a
Crocodile Upstream
Mbombela
17
8
Crocodile within Mbombela
10
1
Sabie Upstream Mbombela
0
0
Sabie within Mbombela
1
0.5
Total
28
9.5
Options To Increase The Water Availability
Groundwater Development
• Groundwater resource hold opportunities at most of the
water demand centres.
• Special techniques for Borehole siting are recommended,
e . g.
‒ High density airborne Survey.
‒ Radon emanation technique.
• Estimated yield increase – approximately 100 000 m3/a –
200 000 m3/a per water demand centre.
Options To Increase The Water Availability
Areas with High Groundwater Potential
Options To Increase The Water Availability
Options To Increase The Water Availability
System Operating Rules
• Real - time operational model for Crocodile River System
- limited scope for reducing water losses.
• Real - time operational model for Sabie River under
development.
• Improved systems operations for White River System
Klipkopjes, Longmere and Primkop Dams is possible
and could increase the yield by at least 1 million m3/a .
Options To Increase The Water Availability
Eliminating Unlawful Water Use
• Extent of unlawful water use in the entire catchment is
currently unknown.
• Will become known after completion of Validation and
Verification Processes.
• This option has not been factored into the Water balance
as yet, owing to the uncertainties.
• Definite possibility and needs to be investigated further,
and if possible included in final strategy.
Options To Increase The Water Availability
Water Reallocation
• Full water entitlement can be purchased from interested
irrigation farmers.
• Needs to be implemented with caution, to avoid social
consequences.
• Fallow irrigation lands with no farm workers should be
targeted.
• Water saved through WC/WDM could also be traded.
Options To Increase The Water Availability
Dam Construction
Six dams considered:
0 – 20 million m3/a yield:
‒ Boschjeskop Dam( Nels River)
‒ Ngodwana Dam Raising ( Ngodwana River tributary of Elands River)
‒ Lupelule Dam on a tributary of the Elands River
> 50 million m3/a yield:
‒ Montrose Dam - Crocodile River
‒ Mountain View Dam - Kaap River
‒ Strathmore Dam – Revolver Creek.
Options To Increase The Water Availability
Dams Investigated
Options To Increase The Water Availability
Dam Construction (Continued)
Dam
Capacity
million m3
Yield
million m3/a
URV @ 8%
R/m3
Boschjeskop
130
20
R 4.50
Ngodwana
Raising
100
20
R 19.00
Lupelule
23
7
R 16.50
Mountain View
60
50
R 0.53
Strathmore
60
75
R 0.50
Montrose
210
60
R 4.50
Options To Increase The Water Availability
Dam Construction (Continued)
• Of the six dams evaluated, two could immediately be
discarded on financial grounds, i.e.:
– Raising of Ngodwana Dam
– Lupelule Dam
• Montrose Dam’s URV is relatively high and there will be
significant environmental impacts
• Three dams remaining to be considered, i.e.:
– Boschjeskop Dam
– Mountain View Dam
– Strathmore Dam
Options To Increase The Water Availability
Dam Construction (Continued)
• If Mountain View or Strathmore dams are chosen, a
water exchange needs to be made
• Downstream irrigators who currently receive their water
from Kwena Dam will now be allocated out of Mountain
View or Strathmore Dam
• More Kwena Dam water can then be made available to
parts of MLM area located upstream of Kaap/Crocodile
confluence
• Social, financial and environmental implications of such
a exchange needs to be investigated
Montrose Dam
Options To Increase The Water Availability
Environmental Screening Criteria Used
• Mpumalanga Biodiversity Conservation
Plan (MBCP)
• National Freshwater Ecological Priority
Areas (NFEPA)
• Water Quality Impacts
• Socio economic impacts
Options To Increase The Water Availability
Conclusion of Environmental Screening
• In summary, the dams which will have the least impact on
the surrounding environment would be Mountain View,
Strathmore and Boschjeskop Dams.
• If social and environmental impacts are taken into
consideration, Mountain View Dam and Strathmore Dam
would be the preferred options.
Options To Increase The Water Availability
Water Resource Classification
• Sabie River currently in A/B Ecological Category.
• If Sabie River Reserve is optimised additional yield may
become available.
• Subject to full stakeholder engagement process.
• This will be part of the resource classification process of
DWA.
• The Crocodile River situation can also be investigated
• The classification project for the whole Inkomati WMA
has started
Options To Increase The Water Availability
Rainwater Harvesting
• Rainwater harvesting can reduce the reliance of water
users on surface water resources.
• It is however not a solution on its own and can only
supplement water supplies.
• It is estimated that full implementation of rainwater
harvesting will reduce the reliance of existing sources by
about 5%.
• However, rainfall harvesting is not yet competitive in
terms of cost.
• It is however recommended that municipal bylaws be
passed compelling all new housing development to be
installed with rainwater harvesting tanks.
Options To Increase The Water Availability
Fog harvesting
• The escarpment to the south of Nelspruit experiences
high incidences of fog and there is potential for fog
harvesting to supply domestic water needs.
• Kaapsehoop could benefit from such a scheme.
• However, the amount of water that could be harvested is
difficult to determine without a pilot plant.
• It is recommended that a pilot plant be constructed at
Kaapsehoop.
Options To Increase The Water Availability
Water reuse
• The reuse of water through treating domestic and/or
industrial effluent is an option which would reduce the
reliance of water users on fresh water sources.
• The process is however relatively expensive.
• Water reuse is practiced in several towns and cities in
South Africa but is mostly applied for industrial and
mining use.
• The reuse of effluent for domestic purposes is less
common. Its an option that is being actively promoted in
Durban as a viable reconciliation option but there is
some resistance to the concept on cultural grounds.
Options To Increase The Water Availability
Water reuse (Continued)
• In the case of coastal cities and towns which discharge
effluent into the sea there is a direct benefit to reuse of
effluent.
• In the case of inland recycling the benefit is less since
the effluent is generally discharged into the river and is
already being used by downstream users.
• There is no legal requirement for municipalities to return
their effluent into the river. They may reuse it if they wish.
This could however have implications on downstream
users who are already indirectly using this effluent.
Options To Increase The Water Availability
Discussion