Poorly planned dams in Uttarakhand which were constructed without paying heed to their environmental impact is seen as one of the reasons why floods turned so devastating in the state this June. Experts say there is an urgency to reassess the need of hydropower in the state and make hydro energy sustainable.
While dams are needed to meet energy requirements, building them is a construction-intensive activity. It involves blasting, excavation, debris dumping, movement of heavy machinery, diversion of forests and rivers. This can cumulatively impact Himalayan ecology.
According to the website of Uttarakhand Jal Vidyut Nigam Limited, 45 hydropower projects with a total capacity of 3,164 MW are operational in Uttarakhand, and around 199 big and small projects are proposed or under way in the state. In the Alaknanda-Bhagirathi (tributaries of the Ganga) basin alone, which is said to be most impacted, 69 hydropower projects with a total capacity of 9,000 MW are under way, according to the high level Inter-Ministerial Group (IMG) formed by the Union Ministry of Environment and Forests to consider matters relating to environmental flows and hydropower projects on the Ganga and its tributaries. The report was prepared in April 2013. These projects would modify the key tributaries through diversions to tunnels or reservoirs. As per the report, implementation of all 69 projects would affect 81 per cent of the Bhagirathi and 65 per cent of River Alaknanda http://www.downtoearth.org.in/content/rush-hydropower-projects-ganga-tributaries.
Damage from run-of-the-river projects
Most of the 69 projects are lesser than 25 MW. But even small run-of-the river projects can cause severe damage to the rivers. They re-route water through tunnels, cutting through mountains to increase the pressure, leaving long stretches of river dry—for instance, the 10 MW Madhya Maheshwar SHP plant in Uttarakhand uses a 4 km-long tunnel to divert water. What's more, a large number of these projects are at very short distances from each other, leaving little space for rivers to regenerate and revive. “A lot of wrongdoing happens in small plants because no environment impact assessment is required,” said Vimal Bhai of Matu Jansangathan, a non-profit in Haridwar.
In Kedarnath where maximum disaster impact was seen, Larsen and Tuobro is building a tunnel for a 99 MW hydro power project. “Since 2007 when the work started, cracks have formed in the houses in adjoining villages like Mekhanda and Phata,” said Shalini Dhyani, scientist at G B Pant Institute of Himalayan Environment and Development. The entire ecology of the area has changed since the construction of the dam has started there. The water bodies have dried up in lower areas and the region has been experiencing lesser rainfall since past four to five years, she added.
Maintain ecological flow
One big consequence of poorly planned construction of hydro power projects is reduced ecological flow of rivers. Ecological flow or e-flow is the water that should be left in the river for ecosystem protection and livelihood purposes at all times. IMG recommended 30 per cent ecological flow in lean season (November to April) and 20 per cent ecological flow from May to October. To this, many environmentalists submitted a dissent note. Centre for Science and Environment (CSE), after an extensive analysis of hydrological data of 24 hydropower projects, provided an alternative view to IMG. It found that winter (lean) flow is less than 10 per cent of the high monsoon flow in almost all 24 projects. And, if less than 50 per cent water is left in the river, it will be reduced to a trickle in these months. Therefore, CSE suggested for 50 per cent ecological flow for six months in lean season and 30 per cent flow in remaining six months. Based on its analysis, it said that it is possible to build hydropower projects on a river and still allow this flow. The energy generation would also not be impacted substantially. CSE also suggested minimum distance between two projects as three to five kilometres.
It is worth noting that way back in the 1980s when Central Electricity Authority estimated hydropower potential, it did not take into account ecological flow, competing needs of society for water or indeed anything else.
Cumulative impact not assessed
As cumulative impact study is not mandatory in the existing Environment Impact Assessment (EIA) process, the project proponents and the government hardly take it into consideration. Cumulative assessment becomes even more important in case of hydropower projects on a river system to understand the impact of the existing projects on the ecology and how feasible is it to build new projects in the same basin. “There are environment protection guidelines for development of hydropower projects but they have largely remained on paper,” said a senior faculty member of civil engineering department of IIT-Kanpur, requesting anonymity. Guidelines also say that suitable dumping sites for disposal of debris and waste generated during construction should be identified well in advance. “But no proper muck disposal mechanism is followed. The deposition of muck and debris of a dam located upstream on the river banks downstream is a common practice,” said Anil Joshi, director, Himalayan Environmental Studies and Conservation Organisation, a Dehradun based non-profit. “ Indiscriminate dumping of muck increases erosive capacity of a river manifold during monsoon. It causes extensive destruction downstream,” said Y P Sundriyal, professor of geology at Hemwati Nandan Bahuguna Garhwal University in Shrinagar, Uttarakhand. Experts also say that the government should invest more in increasing the efficiency of the existing projects so that fewer projects are needed. This includes minimising transmission and distribution losses which are to the tune of 30 to 40 per cent.
Review reservoir limits
In view of the recent news reports that reservoirs of certain dams like Ramganga are overflowing 440 per cent above normal, scientists say there is a need to review certain criteria like “design flood”, which accounts for a probability of a disastrous flood, experienced once in hundred years. “This estimation helps in reviewing the reservoir storage capacity of dams so that they are better equipped to deal with the increasing precipitation variability,” said A K Gosain, professor with civil engineering department at IIT-Delhi. However, the Indian standard for fixing the criteria for design flood for safety of dams has not been directly incorporated the concept of hazard. Engineers seldom take it seriously, says a 2012 study titled Hydrological Safety of Dams in India, by N K Mathur and Bhopal Singh of Central Water Commission. Thus, there is a need to take up the task of hazard assessment seriously and modifying the design criteria accordingly, adds the paper. It also highlights that the India Meteorological Department, which is required to undertake storm studies for projects, is incapable of doing so because of manpower shortage and other constraints.
However, G P Patel, managing director of water utility UJVNL, insisted that dams have no connection with the floods. “Had dams like Tehri not been there, devastation could have been manifold. If it had not been for the dam, entire Rishikesh and western Uttar Pradesh would have been washed out,” he added. On June 16, when the Bhagirathi was swelling, the water level in Tehri dam reservoir reached 775 metre from 750 metre. The reservoir can accommodate water up to 830 metre from the mean sea level. “The current water level in Tehri dam is 778 meter which is abnormal. The highest so far has been 763 metre in 2008. Had it been October, the devastation would have been much more,” said an engineer of Tehri Hydropower Development Corporation, seeking anonymity. More rains could spell disaster.