Recent dam failures in Libya and Ukraine have re-emphasized the great importance of improving dam safety. The flood disaster in Libya was greatly aggravated by the heavy damage to Wadi Derna dams very recently leading to several thousand deaths, even though clear warnings of the lack of poor maintenance of these dams had been given earlier. These could not be attended to because of civil war type conditions in Libya for several years leading to terrible neglect of essential infra-structure needs. In Ukraine the wartime damage to Nova Kakhovka dam may or may not have been intentional but certainly it caused a lot of problems for people, apart from the damage to dam leading also to problems for the safety of a nuclear plant whose cooling water needs were being met by this dam.
The fact that both of these disasters were related to war and civil war conditions is also a reminder that when dangers are increasing a lot due to climate change, it is completely foolhardy to go on increasing them by wars and civil wars instead of diverting the energy of entire humanity to protection from climate change and related risks. In an ideal scenario, most of the military personnel, with their jobs and salaries fully protected, would be retrained to now function as disaster prevention officers, rescue personnel and eco-warriors, saving human lives and saving biodiversity and environment instead of killing people and ruining environment.
What must be clearly realized is that the overall danger of floods as well as dam disasters has increased greatly in times of climate change. Already we can see so many episodes of very high rainfall being concentrated in short periods leading to unprecedented floods in several areas, and this can accentuate further. Hence dams built on the basis of previous data are in any case coming under pressure in unexpected ways. At the same time there are several examples of adequate attention not being given to dam safety, starting from wrong approval being given to the construction of unsafe dams ( under the pressure of powerful construction lobbies) and continuing on to less than adequate attention being given to safety in maintenance and management.
If we count only the bigger dam failures, nearly 200 such failures were reported during the first decade of this century, while the smaller incidents would be simply too many. During 2005-13, nearly 173 dam failures were reported in the USA, big or small, or about 19 per year. Hundreds of structures need better care here, while the average age of dams here is already 65 years. In China’s dam failures the most number of deaths have been reported.
The situation with respect to dam safety is serious not just in failed states or those close to this situation; it is also a cause of great concern in leading countries like China, the USA and India, which are known to be the biggest dam builders in the world. In the case of the extremely controversial Tehri Dam Project, in India it was in fact an officially constituted experts committee (river valley projects appraisal committee of the Union Ministry of Environment) which had stated explicitly that the risks of this project were unacceptably high and the project should be given up. What was the action on this recommendation – the project work was speeded up further!
During the last 65 years nearly 50 dams have collapsed in India. The case for more adequate safety monitoring has become stronger because of the growing threat of Reservoir Induced Seismicity (RIS). Recent evidence from China, particularly the Three Gorges Project, indicates that this threat can be much bigger than what was earlier believed. The seismicity here has increased greatly after the impounding of water and over 3000 small quakes have been reported, leading to the eviction of about 300,000 people affected by resulting landslides.
One of the biggest tragedies caused by dams in India, the Machu dam disaster of August 1979 killed several hundred people and destroyed Morvi town as well as several villages. According to the Consumer Education and Research Centre, Machu dam was designed on the basis of outdated empirical formula. Although in the course of the project study conducted before constructing this dam the Central Water and Power Commission had thrice asked the state government to check on a more scientific formula for the construction of the dam, the government went ahead with the construction of dam without having carried out this exercise. It was only at a very late stage when a major share of the dam had already been constructed that this exercise was conducted, and then somehow the findings were tailored to fit in with the almost already constructed dam.
In addition the following other cases of dam failure in India may be mentioned —
Kaddam Dam – following heavy rainfall in the catchment, this composite dam failed in August, 1959. This failure was attributed to inadequate spillway capacity.
Chickahole dam (1972) – This masonry structure failed in December 1972 due to tension caused at dam base on account of water level rising to top of the dam.
Dantewada (1973) – A breach occurred along the reservoir periphery in September 1973.
Aran (1978) – This case of earth dam failure has been described as a classic case of foundation failure generated by seepage.
Jaswant Sagar dam – This dam in Rajasthan breached in July 2007 despite the fact that it was supposed to be monitored under the World Bank funded ‘Dams Safety Assurance and Rehabilitation Project”.
Gararda – This dam in Rajasthan collapsed in August 2010. The enquiry committee report highlighted serious negligence and corruption leading to substandard work.
Another fact which may be pointed out is that the rehabilitation of the victims of dam failure often leaves much to be desired. In 1961 the earthen dams at Panshet and Khadakwasala dam (Maharashtra), breached, bringing death and destruction to the villagers. About 200 lives were lost, and 14,000 families were rendered homeless. Despite the rehabilitation efforts made by the government the life of these victims remained uncertain for a long time.
Thus heavy damage and large scale distress has been caused by dam failures in the past and as most suitable sites have been exhausted and future dams are being built at more difficult sites, such as in the Himalayas, the need for caution can hardly be over-emphasized. An adequate machinery to assess hazards of projects before they are constructed and to monitor their safety after they start functioning is a must. Adequate financial provision for this should be made.
There have been some cases when we have come quite close to major dam distress. Fortunately these have been averted. But the near failure should be cause enough for a thorough review of the safety aspects. Such a review, it appears, is not made in such cases. According to statements made by senior officials themselves, the giant Bhakra dam has come close to failure twice at the time of torrential rainfall and heavy inflow of water. Similarly the Farakka project came under a cloud as in 1989 the irrigation Minister of W. Bengal himself sounded warnings about the threat to the safety of this structure.
It was due to lack of adequate consciousness about dam safety that recently the Mullaperiyar dam issue was converted into an inter-state issue between Kerala and Tamil Nadu while it should have been treated first and foremost as a dam safety issue. The first step should have been to ensure the safety of people affected by a threatened dam.
The entire issue of dam safety should be taken forward in a more open and transparent way with adequate space for independent experts and affected people to be heard properly.
A broader concern is that over 50 years have passed since the peak period of dam construction at world level (while several dams are much older) and hence this is the time to look very carefully at whether several ageing dams would be able to withstand the exceptionally heavy downpours of the times of climate change.
In this situation it is being increasingly seen that very heavy siltation and other factors have greatly reduced the benefits of many dams, to keep them safe very costly repairs are required in some cases. In the case of the Kariba dam in southern Arica the repair bill amounts to nearly 300 million dollars. In other cases it is being realized that the harm caused to fish and other aquatic life has been much more serious than what was anticipated. The grave harm caused to the salmon breeding cycle in the Snake river with fish moving from ocean to mountains for this has been cited, but there are also many other examples of fish breeding, survival and migration routes being very badly disrupted. In the USA the remaining indigenous people have contributed much to this realization, which is being more widely accepted now, so that in many cases the planned removal of dams and restoration of rivers to their natural flows is now considered to be the best option available. This is being attempted at several places in the USA and Europe today. The Elhwa river system restoration in the USA, the removal of 4 dams in Khamath river and the Meuse river restoration in the Netherlands have been cited as examples of this. Such planned dam removal should be considered in the case of some of the most high-risk dams such as the Tehri dam in India. At the same time some of the high-risk dams which are under construction, such as by China in the Tibet reach of Brahmaputra River, should be given up at the right time.
Bharat Dogra is Honorary Convener, Campaign to Save Earth Now. His recent books include Planet in Peril, Man over Machine and A Day in 2071.
