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LESOTHO HIGHLANDS WATER PROJECT PHASE
2OVERVIEWBy P D Pyke
October 2012
Yield analysis - Polihali
• Dam yield ( MOL 1992, FSL 2065) viewed in isolation:– 14,75 m3/s 465mil. m3/a
• Incremental Orange River system yield– 5,76m3/s 182 mill.m3/a
• Phase 1 Dams Yield • 780 106 m3/annum• 24.7 m3/s• Polihali Contribution to System Yield (of LHWP)• 465 106 m3/annum• 14.75 m3/s• Total LHWP Phase1 and Phase 2 Yield • 1271 106 m3/annum• 40.3 m3/s - but also need yield replacement
dam for Orange River
Polihali Yield Analysis
Main Embankment
Main dam
Maximum height 163.5 m
Essential Excavation 40 000 m3
Dam fill volume 12 311 210 m3
U/s and d/s slope u/s 1: 1.4d/s 1:1.25, average 1:1.4
Crest width / length 10 / 915 m
Reservoir Volume 2 322 million m3
Surface area 50.4 km2