I had the opportunity of visiting the first 'Indian' dam to be built post independence and the largest in Maharashtra. The Koyna dam (actually the surroundings of it). Situated in the lush green Sahayadri range in western ghats, this dam is actually a collection of 4 mini dams. The large backwater apart from mainly providing hydroelectric power, irrigation and potable drinking water has made the surrounding forestation evergreen. The koyna dam appears very small as compared to others in the himalayas but still its unique engineering vision has made it really very special. Its 4 phases have ensured year round supply of water and electricity; even in the harsh month of May.
On reaching the hill-top overlooking the dam -site we saw just the first phase,this is the oldest and is a conventional hydro-electric power dam. But as always there always "more than what meets the eye" .All the remaing 3 phases are actually underground with water diverted to the turbines via tunnels cutting over 4km through the mountain range. The expanse of the mountain and the idea implemented left us spell bound, literally. The planning and excecution of this task is an engineering masterpiece with perfect management of the human needs and the geological and ecological balance.
We also got an insight into a technique called 'lake tapping' used in the third phase. Here the backwater (level which is the highest of all in summer) is diverted up the slope through a tunnel 80 meter in diameter. The water level pressure itself is used as a pump. So, a deep trench is dug underneth the expected trench. The expected trench (used to divert the water) is then exploded, with the water pressure pushing the debris down into the deerper dug trench; therby completing the water path to the turbine.
There is also a safety feature built into the entire system. By means of two surge wells over 800 meters deep, the backwater is allowed to swell in flood situations without overflowing from the dam. The enegry of this water is also harnessed to generate electricity. Standing on the cliff of the mountain with greenery sprawling all over, along with the gentle humming of the underground turbine was an amazing experience.
So now after trying to provide you the technical details, i must inform
you that 'permission' (read influence) is required to actually visit the dam site, the hydro-electric stations and the underground power stations. Having no such luck...we setteld for a virtual tour of the engineering marvel at Koyna provided by Nishigandha Vad; screened daily at the popular Nehru Udyan just flanking the main dam. Another point of note is that due to security arrangements( by way of jammers) no cellphones are of any use here. This i feel is a blessing in disguise, for giving us two days of completed respite.
We realy enjoyed our stay at koynanagar amidst the lush greenery, the local village folk and a total lack of any 'visitors'. Telling people that Koyna is a good place to vist, i find them stumped.
Hope you are too. :)
Happy Travelling !
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