Mapping Nepal’s water recources
Harnessing all of Nepal´s hydropower resource would require the building of about 60 run-of-river power plants and 30 reservoir/dam projects in the middle hills. The construction of the high dams and reservoirs would, among other things, require the re-drawing of the physical map of Nepal to show the large bodies of water which would become part and parcel of the Mahabharat and Churia landscape.
Seven of the 30 reservoir/dams proposed—in various studies and reports over the last four decades—would be between 50-100 meters in height; 12 would be between 100-200 m; and 11 of the ´high dams´ would be of more than 200 m.
Upon completion, the 90-odd projects would generate about 145,000 GWh (giga-watt hours) of electricity annually. The energy produced would be sufficient to meet the needs of´700 million average-sized South Asian families. If one were to complete all the projects and export the energy, it would provide the Nepali state with millions of dollars revenue every year. Irrigation for millions of hectares in the Ganga plain, command area development, regional flood mitigation, and navigation would be the additional benefits.
Construction of these projects would require about five million tons of steel, 100 million cubic metres of concrete, and 1000 million cu m of "rip-rap rocks" and filler materials gouged from nearby hills and mountains. Several hundred kilo-metres of conduits would have to be tunneled through the mountainsides. (For comparison´s sake.
Kulekhani hydropower project southwest of Kathmandu has 10 km of tunnels, and used about 70,000 cu m of concrete, 4500 tons of steel, and 3.5 million cu m of rocks and filler material.)
At current rates, about U$ 300 billion would be required to tackle these 90 projects, which cumulatively would take a total of about 500 ´nation years´ to complete. Kulekhani took six ´nation years´ to build, and cost U$ 125 million. It generates 165 GWh of energy, which is 0.11 percent of Nepal´s total potential.
Storing a total of144,000 million cu m of water, the 30 reservoirs would regulate the seasonal high discharge of the rivers into constant flows. They would also trap the bulk of the over 700 million tons of sediment transported downstream annually by Nepali rivers, eventually filling each reservoir 30 to 75 years after impoundment has begun.
When all the projects have been completed, 2200 sq km of Nepal´s surface area will be under water. This translates to about 1.5 percent of the country´s surface, including 20 percent of all irrigable land in the hills, besides forests, bari (unirrigated land), homesteads, and community land. At least 100,000 families (about 600,000 individuals or 3 percent of the present-day population) would have to be moved from the submergence zones.