Mega hydro structures – bold, innovative and impressive solutions for a large Dam with engineering challenges: Tehri Dam

One of the recent engineering marvels in hydraulic mega structures in india is the Tehri Dam across the River Bhagirathi, a tributary of the River Ganga.

In the face of the threats posed by climate change, water storage has assumed greater relevance. Developing countries with the trend of increasing population have to rely more and more on storage dams for their growth as water is basic to achieve development and welfare to the society. The decrease in the availability of water with ever growing population has placed india in a water scarce situation, as per capita availability. The spatial unequal distribution of the natural precipitation with the monsoon which shows an increasing variance adds further woe. A proper management of water resources therefore leans upon the science and technology as the tools for solution.

Water Resources development in indian settings is complex given the population pressures in areas to be submerged by reservoirs behind storage dams. Despite the progress made during the past six decades lauded as significant, enough per capita storage to insulate the country from water stress is still at a distance. This is likely to impact adversely the requirements for agriculture, industrial water needs leave alone the drinking water demand for ever growing large cities. With the exhaustion of available easier sites for dam sites, dams are to be planned, designed and constructed with innovative solutions suiting the intricate topographic, geologic and geotechnical condition. The designs of not only the main dam structure but also associate ones like the spillways, energy dissipaters to handle the flood waters, large underground caverns for hydro power generation, handling high sedimentation rates with desilting chambers and long water conductor systems under difficult terrains particularly in Himalayas are some of the challenges before the dam engineers. indian Engineering profession has been able to rise up to the challenges. Recently it has brought in concepts that are bold and sound.

The author had the privilege to be associated with over 100 dams in india as an expert in the central Water Commission, the apex technical organisation in India in the field. A few of these dam and barrage structures are in the highest range of dam heights with complex geological and topographical settings with novel solutions embedded in them. in an attempt to crystallize the author's experiences in different aspects of dam designs, this brief paper for the indian national Academy of Engineering aims to bring home certain world class planning and design concepts followed design and engineering of the Tehri Dam in the Himalayas.