Despite foregoing dedication, dams are a sort of a necessary evil. Hydroelectric power is considered to be one of the cheapest and cost effective sources. A dam across a river valley is supposed to be the ideal solution to meet the crisis of water and electricity.

Impressions of a Geologist

The white painted line across both flanks of Bhagirathi River near Tehri in Uttaranchal (then U.P.) in 1974 evoked lot of academic interest for me during a survey stint in that area. The white line marked the axis where the Tehri dam stands today. Unmindful of our presence children were playing cricket on a ground at the then Tehri town located on the bank of the river on a huge flat formed due to blockade of Bhilangana and Bhagirathi Rivers may be few million years ago. The play ground now lies submerged under 100 meter water column of the Tehri reservoir.

The white painted line was awe-inspiring though not without a fear in mind, 'suppose there is an earthquake?' These were allayed by the seismologists who contended that the design of the dam would be such that even an earthquake of more than 8.5 on Richter scale would not harm the dam structure. Yes, an earthquake above that would be a catastrophe, dam or no dam.

Tehri dam through its different stages of construction generated different kinds of feelings and fears. Much later when a Coffer dam had been made to divert the stream to facilitate the work on the site, the gorge of the Bhagirathi River looked ferocious than ever. The din of the crushers and dumpers carrying the material subdued the protests of anti dam lobbyists.

To a geologist or an engineer a dam is like a patient to a doctor. He tries to examine the patient to cure him, without any personal attachment. But for others the patient may be a son or a father who watch with an anxiety written large on their faces while the doctor administers an injection. Likewise, for a technocrat the social issues like the fate of the residents of the habitations likely to be submerged or their vocations etc have little meaning. It was enough to learn that the population affected would be shifted to the New Tehri town being constructed on the ridge almost overlooking the Tehri dam.

Being an Uttaranchali I know how different is the life in the valley, from that on the ridge top. The valley offers scope for some agriculture. Climate is warmer, winters are less severe. Water shortage is unheard of in the valley, whereas families on the hilltop have to get used to manage with rationed amounts of water and the flat fields of the valley are replaced by the terraced mini fields. Valley farmers are used to cultivating rice, up on the terraced slopes they have to be content with potatoes. One gets a picturesque view of the Reservoir from the New Tehri. But the trauma of leaving homes, to watch them submerge slowly and living in a completely different environ has to be experienced to realize.

However, for the planners and technocrats occupying air-conditioned offices rice and potato have hardly any meaning. Their target is in terms of generation of so many MW of electricity and release of so many Cu Secs. of water for irrigation and drinking.

A Society Divided

A dam is an engineering marvel. Tehri dam is something special with the power wielding turbines in the womb of the mountain. While the dam stores water in the reservoir and generates power, controls the floods and irrigates the parched lands, it divides the river and the society in to two parts. The dammed part has the reservoir and the damned people. The other side has the Power. It was pathetic to read a newspaper report while the agitation against the dam at Tehri was on. The report said, '...and moreover only a handful of Garhwalis live along the river'. Wish one of them was the reporter's kin!

It is indeed intriguing that even after 59 years of Independence those 'ousted' from their homes by anthropogenic or natural reasons have to live on pittance. While the infrastructure development is a must the human angle needs a lot of foresight, planning and timely execution of rehabilitation plans. Unfortunately, the common man does not come in touch with the policy maker he is at the mercy of the government official distributing relief. Many times the government official is heard saying, 'you are getting a huge compensation but what do I get?' The person displaced by such a project thus gets two kinds of jolts, one of leaving his home and other of paying a cut for his rightful claim.

Is Tehri Dam Safe?

The Himalayas like an adolescent are still growing. That is why the Himalayan eco-system is fragile. Engineering marvel, Tehri originally designed like any other dam for 100 years is likely to stay there for 62 years only, says a report of TERI. It is the reservoir that would be most affected with the passage of time.

While all the fears of a disaster have been allayed by the technocrats the impact of the Reservoir Induced Seismicity (RIS) and heavy landslides creating artificial blockade in the upstream of the dam have not been well clarified/publicized.
The science of RIS itself is in adolescence. The first observation of RIS was made by Evans in 1945 at the Hoover's dam reservoir. He proved that variation of the water level of the reservoir was the culprit for the increased seismicity. Major earthquake event occurred after five years of filling of the reservoir.

The notorious Koyna earthquake of 1967 in Maharashtra was an outcome of RIS and has been studied in detail.

Information of RIS is fundamental for making an aseismic design. The thumb rule that induced seismicity would not exceed the expected maximum natural seismicity is strictly followed. However, nature like human life is unpredictable.

Lest the nature's fancy take a turn the monitoring of the RIS for Tehri reservoir has been assigned to the IIT Roorkee.

Apart from the RIS the possibility of a landslide damming the Bhagirathi or one of the tributaries upstream can not be ruled out. Annals of the GSI are full of such slides. The worst was the landslide of 6th September 1893 in Birehi Ganga, a tributary of the River Alakananda. The blockade created a 1000 feet high dam across the river at Gohna, 160miles north of Haridwar and a four-mile long and one mile wide lake was formed. Upon bursting of the blockade flash floods had submerged habitations along the river at Chamoli and even at Haridwar. Similar dam formed on the Pareechu River a tributary of Sutluj River in Tibet caused flash floods in 2000 in H.P. killing 70 persons and 100 bridges were swept off.
Such a disaster can spell doom for the Tehri reservoir and the area downstream. Recommendations of the experts from GSI and monitoring reports on the RIS and landslides in the catchments of the Tehri reservoir have to be implemented religiously from time to time by the government concerned to obviate the risks. 
Simulation studies carried out by the Indian Institute of Remote Sensing (IIRS), Dehradun in 2002 revealed that out of the 5170.20 hectares of area to be submerged under the reservoir more than half is the precious agricultural land. The submerged fluvial terraces of the Bhagirathi River have also aggravated the chances of increased mass wasting processes. Social forestry along the rim of the reservoir will certainly 'hold' the slopes around the Tehri reservoir.

Studies in such reservoirs elsewhere in the world have indicated an impact on the micro-climate of the area. A careful watch on Tehri reservoir for such impacts is a must.

Do We Care!

Fishes in the river are a means of livelihood for those living on the river banks. The fishes of the Himalayan Rivers have a peculiar trait of swimming upstream particularly in the breeding season. While fiddling with the geo-diversity in order to create the behemoth called Tehri Dam we did give an academic thought about the fishes. As mentioned in some news paper reports earlier 'fish lifts' would be constructed, whether they came up or not is not known, but there are fishes that are bottom dwellers, who migrate downstream during winters may have no option but to become extinct!

Dream of Narmada

How much prosperity Tehri dam would bring, only time would tell. After Tehri now Narmada projects are in the midst of turmoil. The concept of several dams across the Narmada River came up in 1946. In six decades residents of the affected area could have been gradually settled in the areas developed for them, but those doomed masses now termed as the Project Affected People (PAPs) have no option but to agitate. Many of them are now landless in their own land. Various 'relief measures' are being innovated everyday to sooth them. Easiest way is to dole out money. Can they buy their happiness, their fields and play grounds with that money!

Well dams are essential, but so are the lives and occupations of those affected by the project. Why should they need to agitate and fight cases in the courts of law? Is the torture of those damned by the dam essential?