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Step 2: Optimisation of the preferred IFR
Report No 678-F-001
METSI CONSULTANTS: SUMMARY OF MAIN FINDINGS FOR PHASE 1 DEVELOPMENT
Once the bulk allocation of water to be made available for IFRs has been made, the optimal allocation should be
made to achieve the best environmental outcome. This would require hydrological modelling of system reservoir
and allocation of water to low flows and floods for the best environmental outcome using the biophysical data
collected during the course of this study.
Step 3: Formal agreement to the IFR
This stage involves agreement of all parties involved on IFR releases considering the output of Step 2. While the
outcome of Step 2 could lead to an agreed IFR, the implementation of IFR operationally would need formal
agreement.
After an agreement had been reached on IFR releases, the reservoir operation plans would need to be prepared.
This is referred to as the annual plan of operation, which will provide boundaries for operation of all completed
reservoirs including the Matsoku Diversion. Releases to meet the agreed IFR will depend on reservoir inflows and
prevailing reservoir storage levels, information on which needs to be updated on a weekly basis. The annual plan
of operation may require updating over time, depending on precipitation and the reservoir inflows.
Establishment of an acceptable IFR is but one step in the overall management of the LHWP and cannot be
effectively implemented in isolation. Decisions on IFR implementation will have to take cognisance of several
inescapable facts:
Katse Dam has been completed to a design that seeks near-maximum diversion of Malibamats'o River
flows, makes minimal provision for downstream ecosystem maintenance, and has little flexibility or
capacity for maintaining downstream IFRs.
Mohale Dam and Matsoku Weir are nearing completion to designs which permit somewhat more leeway
than Katse Dam in setting realistic release schedules but which are still highly constraining, e.g., Mohale
Dam cannot release more than a 1:2 year flood.
The current LHWP Phase 1 compensation programmes, embedded in the respective Environmental
Action Plans, are restricted to the immediate catchments above Katse and Mohale dams, and it would
require a major revision and considerable additional expense to extend them to encompass the relevant
downstream areas.
14.2. STRATEGIC APPROACH TO OPTIMISING IFRs
The following strategies are recommended in meeting the first and second objectives of the decision-making
process, i.e., identifying a range and optimising the eventual IFRs.
Multiple objectives are suggested, including (as a priority) matching the IFRs in as many river reaches
as possible to maintain as much of the river ecosystems in as good a condition as is practically and
economically feasible.
The upstream compensation programmes should be evaluated and those with the highest rates of
success used as a basis for extension into the downstream areas. Innovative thinking will be required for
programmes that have not been tested over time.
The status quo is a logical starting point, i.e., Katse Dam completed and operational, Mohale and
Matsoku being constructed with specific limitations on their release capacities (Annex D), and the
existing Treaty in force with its downstream release stipulations and conditions for maintaining
environmental quality and well being of affected communities.
The system under study would best be partitioned for more effective application of mitigation (permitting
an adequate IFR) and planning of compensation; partitioning would optimally be achieved:
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