Situated on the north-eastern tip of the country, the picturesque Arunachal Pradesh is a part of the eastern Himalayan ranges located between 26` 28’ to 29` 30’ N latitude and 91`30’ to 97`30’ E longitudes. The state is bounded by Bhutan on the west, China in the north and north-east, Myanmar on the east and the Indian states of Nagaland and Assam in the east and South-east. In the north eastern region of India, Arunachal Pradesh occupies the largest area (83,743 sq. km) and consists of the submontane and mountainous ranges sloping to the planes of Assam. Physiographically the state is divided into three sections: the flood plains, the foothills and the greater Himalaya.

The flood plains are in the southern portion of the state, the foothills also known as the lesser Himalaya are located between the greater Himalaya and the sub-tropical region. The greater Himalaya comprises areas under permanent ice fields and temperate regions. The mountain peaks show a great variation in height from 1,829 m to 6,400 m. highest peak in Tawang is 7,090 mts.

The five major rivers flowing through the state are Kameng, Subansiri, Siang, Lohit and Tirap, which along with many tributaries finally drain into Brahmaputra. There are 13 districts in the state. The climate varies sharply with changes in topographical and altitudinal aspects. Three broad climatic zones are recognizable viz. hot and humid subtropical area of foothills, cooler microthermal zone of the lesser Himalaya, and alpine zone of the greater Himalaya. The state is one of the heaviest rainfall zones of the country. The average rainfall is more than 3000 mm, being as high as 4,500 mm in the foothills and 800mm in upper reaches. Due to its hilly terrain, the soils in major part of the state are rocky, mainly of Himalayan type: shales, schist and conglomerate. The derived soils are sandy and clayey in the lower elevations of the valleys. Due to high rainfall, the soils are acidic, and because of the extensive vegetal cover also contain humus rich in nitrogen and organic matter.

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