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10.1. PURPOSE OF SECTION
Report No 678-F-001
METSI CONSULTANTS: SUMMARY OF MAIN FINDINGS FOR PHASE 1 DEVELOPMENT
SECTION 10. DISCUSSION OF SCENARIOS
This section summarises the main findings of the IFR study and relates them to the design and possible operation
of the LHWP Phase 1. This section and the succeeding one are framed so as to provide a bridge between the
scientifically-designed and executed IFR study and the needs of decision-makers who will determine the ways
and means of operating and further designing the LHWP. The design of the IFR study with its detailed biophysical
and socio-economic comparison of scenarios that range from minimal environmental degradation, on one hand,
to near-maximum diversion of system flows on the other, provides a comparative basis for drawing important
conclusions on river ecosystem resilience and sustainability. The substantial biophysical and socio-economic
database provided by the study furthermore provides a quantitative basis for comparative conclusions and for
future refinement of IFR determinations.
10.2. ISSUES RELEVANT TO THE TIMING OF THE IFR ASSESSMENT
Under more ideal conditions the IFR study would have preceded major design and operating decisions for the
LHWP. This was not the case, and the IFR study was commissioned well after the construction of Phase 1A and
during the course of final design and initial construction of Phase 1B. A number of significant changes occurred
between the mid-1980s, when Phase 1 of the LHWP was studied and designed and the LHWP Treaty formulated
and signed, and 1997, when the IFR study was initiated.
Phase 1 was designed and Phase 1A constructed on the assumption that downstream impacts resulting
from diversion of more than 95% of the MAR would be limited to the proximal reaches of the
Malibamats'o and Senqunyane rivers immediately downstream of the LHWP structures and above the
confluences of the next major tributaries (Khohlontso and Semenanyane for the Malibamats'o, Lesobeng
for the Senqunyane). This has been shown by the IFR study not to be necessarily the case.
The assumption seems to have been made in the initial stages of the LHWP that local people make very
little use of riverine and riparian resources downstream of the LHWP structures. No studies or
assessments of these were conducted prior to the initiation of LHWP development. However, the IFR
field studies have documented an extensive and sometimes complex relationship between local people
and river-related resources such as riparian trees, shrubs and herbaceous species. Utilization of the fish
resource along downstream river reaches by local people was not considered, whereas the IFR study
has documented extensive fish harvesting and local trade in the downstream river reaches.
The existing LHWP compensation programme addresses impacts only in the areas upstream of the
LHWP structures. The IFR study has documented extensive existing and potential future economic
impacts downstream of the structures.
10.3. BIOPHYSICAL IMPACTS
Table 10.1 summaries the predicted biophysical consequences of various levels of flow regulation for each of the
study reaches. Reaches are separated into two classes - proximal (immediately downstream) to the LHWP
structure and distant.
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