Over 60 per cent of the catchment area of the Arun river falls in Tibet; little is known about the hydrological behaviour of the river in this part.
inadequate study of the discharge pattern of the Arun river. critics say that the data collected does not go back more than 10 years, which is insufficient.
Some studies have predicted that the Lower Barun glacial lake, located above the project site, can burst, causing a flood which would wipe out all the invest- ment on the project.
Inadequate seismic study of the area.
For a run-of-the-river project, a 68 m high concrete gravity dam is too big.
The project envisages an 11 km tunnel. In some stretches the tunnel goes through an overburden of 1,506 m. Chances of coming across hydraulic columns are high in. such a case, which can leave the engineers with no option but to abandon the tunnel and try another one. This Is bound to throw the cost calculations haywire.
The 2 stages of the project envisage 2 separate tunnels, which is highly cost-ineffective. One large tunnel would have served the purpose, besides bringing down the costs as well.
The desanding basins are underground; needlessly. Critics say that extravagance like this In design and conception has led to the high costs of the project. The Ist phase can generate as much as 270 mw power, but has been designed for only 201 mw. This is sub-optimal utilisation of the resources.
The selection of the turbines has not been transparent.
The permitted slope and the curvature width of the access road violate the Nepal Roads Standards 204S.