30 CIVIL WORKS GUIDELINES FOR MICRO-HYDROPOWER IN NEPAL
Box 3.1 Composite gabion concrete PVC sheet weir Jhankre Nepal
Figure3.9 Cross section of Jhankre Mini-hydro diversion weir
Photo 3.7 Diversion weir of the Jhankre Mini-Hydro Scheme
The 500 kW Jhankre Mini-hydropower Scheme, located
on the Jhankre river, Dolakha, Nepal, was designed jointly
by BPC Hydro consult and Development and Consulting
Services (DCS). The construction was undertaken by
DCS. As can be seen in the section through the weir, to
minimise seepage in the dry season, a heavy grade
polythene sheet has been fixed at the upstream face of
the gabion weir. To prevent the sheet from being punc-
tured by boulders and other debris, stone backfill has
been incorporated in front of it. Also to prevent the ga-
bion wires from being nicked by rolling boulders, 150 mm
of plain concrete is placed along all exposed surface of
the weir.
During a 1995 monsoon flash flood (estimated to be a 1:30
year return period flood), this weir was partially damaged. It
was then repaired. Since then, the weir has faced two an-
nual floods without any repairs. Occasional repair of the
concrete topping and the gabion wires are expected (i.e.
during the annual maintenance period).