inter-basin transfer from the Periyar to the Muvattupuzha river due to the Idukki project has further adversely affected the downstream flow in the Periyar river. The Parambikulam Aliyar Project (PAP) agreement was conceived to harness and share the waters in the inter-State rivers in Bharathappuzha, Chalakkudypuzha and Periyar basins. Nirar and Anamalayar, tributaries of Periyar are covered under this agreement. Water from these rivers are transferred to the adjacent Sholayar basin as part of the PAP agreement. Due to all the diversions in its basin, the Periyar has lost 22 per cent of its average flow. Ecological significance South of the Mullaperiyar reservoir, at the source of Periyar River, there is an unbroken stretch of about of sheltered, unmodified rainforests within the Periyar Tiger Reserve. These rainforests extend further west into the adjacent Pamba basin within the Gudarakal Forest Range and continue south beyond the Gudarakal Range into the forests of the Achankovil Division. This entire stretch contains about of undisturbed wet evergreen forests typical of the Western Ghats. The forests on the upper reaches of Periyar are mostly inaccessible and is one of the least disturbed evergreen forests left in the Western Ghats. The Periyar Tiger Reserve (PTR) is also one of the most ecologically diverse regions in India. The flora of the reserve is very rich and diverse. Out of the estimated 3,800 species of angiosperms of Kerala, 1,966 have been reported from within the reserve. Nowhere in the subcontinent, has such a large number of taxa been reported from an area comparable to that of the PTR. Apart from this, the reserve also contains an estimated 323 species of birds, 38 species of fish and 44 species of reptiles. The Periyar plateau forms a part of the Project Elephant Reserve 10, which also includes the Agasthyamalai-Mahendragiri hills. The landscape on the Periyar Plateau portion of Elephant Reserve 10 maintains the most intact elephant range in Southern India. This area is believed to harbour about 2,000 elephants and is one of the potential landscapes for the long-term conservation of the species. This population is genetically more diverse and distinct from the much larger elephant population further north in the Ghats. This region is also known for its rich biodiversity. On the other hand, the landscape has also witnessed a variety of developmental activities including commercial plantations, hydroelectric and irrigation projects and other forms of infrastructural development that impede