Silent Valley National Park (Malayalam: സൈലന്*റ് വാലീ നാഷണല്* പാര്*ക്ക്), (Core zone: 236.74 square kilometres (91 sq mi)) is located in the Nilgiri Hills, Palakkad District in Kerala, South India. The area in this national park was historically explored in 1847 by the botanist Robert Wight, and is associated with Hindu legend.

The park is one of the last undisturbed tracts of South Western Ghats mountain rain forests and tropical moist evergreen forest in India. Contiguous with the proposed Karimpuzha National Park (225 kmē) to the north and Mukurthi National Park (78.46 kmē) to the north-east, it is the core of the Nilgiri International Biosphere Reserve (1,455.4 kmē), and is part of The Western Ghats World Heritage Site, Nilgiri Sub-Cluster (6,000+ kmē) THUNDER consideration by UNESCO.

Plans for a hydroelectric project that threatened the parks high diversity of wildlife stimulated an environmentalist Social Movement in the 1970s called Save Silent Valley which resulted in cancellation of the project and creation of the park in 1980. The visitors' centre for the park is at Sairandhri.

The area is locally known as "Sairandhrivanam" literally, in Malayalam: Sairandhri's Forest. In local Hindu legend, Sairandhri is Draupadi, the polyandrous wife of the five Pandavas, who disguised herself as Sairandhri, queen Sudeshna's assistant, while they were in exile. The Pandavas, deprived of their kingdom, set out on a 14-year exile. They wandered south, into what is now Kerala, until one day they came upon a magical valley where rolling grasslands met wooded ravines, a deep green river bubbled its course through impenetrable forest, where at dawn and twilight the tiger and elephant would drink together at the water's edge, where all was harmonious and man unknown. Beside that river, in a cave on a hill slope, the Pandavas halted.

Silent Valley is home to the largest population of Lion-tailed Macaque, an endangered species of Primate. Public controversy over their habitat led to establishment of Silent Valley National Park.

In 1973 the valley became the focal point of "Save Silent Valley", India's fiercest environmental movement of the decade, when the Kerala State Electricity Board decided to implement the Silent Valley Hydro-Electric Project (SVHEP) centered on a dam across the Kunthipuzha River. The resulting reservoir would flood 8.3 kmē of virgin rainforest and threaten the Lion-tailed Macaque. In 1976 the Kerala State Electricity Board announced plans to begin dam construction and the issue was brought to public attention. Romulus Whitaker, founder of the Madras Snake Park and the Madras Crocodile Bank, was probably the first person to draw public attention to the small and remote area.

In 1983 the then Prime Minister of India, Indira Gandhi, decided to abandon the Project and on November 15 the Silent Valley forests were declared as a National Park. On September 7, 1985 the Silent Valley National Park was formally inaugurated and a memorial at Sairandhri to Indira Gandhi was unveiled by Sri. Rajiv Gandhi, the next Prime Minister of India. On September 1, 1986 Silent Valley National Park was designated as the core area of the Nilgiri Biosphere Reserve. Since then, a long-term conservation effort has been undertaken to preserve the Silent Valley ecosystem.

In 2001 a new hydro project was proposed and the "Man vs. Monkey debate" was revived. The proposed site of the dam (64.5 m high and 275 m long) is just 3.5 km downstream of the old dam site at Sairandhiri, 500 m outside the National Park boundary.The Kerala Minister for Electricity called The Pathrakkadavu dam (PHEP) an "eco-friendly alternative" to the old Silent Valley project. The claim was that the submergence area of the PHEP would be a negligible .041 kmē compared to 8.30 kmē submergence of the 1970s (SVHEP).During January to May 2003 a rapid Environmental Impact Assessment (EIA) was carried out. Little more was heard till November 15, 2006 when Kerala Minister for Forest Binoy Viswam said that the proposed buffer zone for Silent Valley would be declared soon.

On February 21, 2007 ex-Chief Minister A. K. Antony told reporters after a cabinet meeting that "when the Silent Valley proposal was dropped, the centre had promised to give clearance to the Pooyamkutty project. This promise, however, had not been honoured. The Kerala government has not taken any decision on reviving the Silent Valley Hydel Project".

On April 18, 2007, Kerala Chief Minister V S Achuthanandan and his cabinet approved the Pathrakkadavu Hydro-electric project and sent it to the Union Government for environmental approval.


Silent Valley gets copious amounts of rainfall during the monsoons, but the actual amount varies within the region due the varied topography. In general the rainfall is higher at higher altitude and decreases from the west to east due to the rain shadow effect. Eighty per cent of the rainfall occurs during the south-west monsoon between June and September. It also receives significant amount of rainfall during the north-east monsoon between October and November.

The park being completely enclosed within a ring of hills, has its own micro-climate and probably receives some convectional rainfall, in addition to rain from two monsoons. In the remaining months, condensation on vegetation of mist shrouding the valley is estimated to yield 15 per cent of the total water generated in the rainforest.

In 2006, the Walakkad area of the park received the highest ever annual rainfall of 9,569.6 mm. In 2000, the figure was 7,788 mm; in 2001, 8,351.9 mm; in 2004, 8465.3 mm; and in 2005, 9,347.8 mm. The annual rainfall received in the valley (at Sairandhri?) was 7,788.8 mm in 2000; 8,361.9 mm in 2001. In 2002, 4,262.5 mm; in 2003, 3,499.65 mm; in 2004, 6,521.27 mm, in 2005, 6,919.38 mm; in 2006, 6,845.05 mm; in 2007, 6,009.35 mm; and in 2008 it was 4386.5 mm. The figure till October 2009 was 5,477.4 mm. Average annual rainfall in the park between 2000 and 2008 was thus 6,066 mm.

The mean annual temperature is 20.2 °C. The hottest months are April and May when the mean temperature is 23 °C and the coolest months are January and February when the mean temperature is 18 °C. Because of the high rainfall, the relative humidity is consistently high (above 95%) between June and December.

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Keywords: Silent Valley National Park, South Western Ghats mountain, rain forests , Karimpuzha National Park,Mukurthi National Park , Nilgiri International Biosphere Reserve,Western Ghats ,World Heritage Site, Nilgiri Sub-Cluster, UNESCO, hydroelectric project , Sairandhri's Forest, Pandavas, Sairandhri, queen Sudeshna,Lion-tailed Macaque, Kunthipuzha River, Snake Park, Crocodile Bank,Indira Gandhi, A. K. Antony , Chief Minister, V S Achuthanandan , Pathrakkadavu Hydro-electric project , topography