other agencies. Chalakudy river itself has a catchment area of , with in Kerala and in Tamil Nadu. Basin The Periyar basin spreads over an area of , most of it in central Kerala. It lies between latitudes 9°15’30"N and 10°21’00"N and longitudes 76°08’38"E and 77°24’32"E. The river drains parts of Idukki, Ernakulam and Thrissur districts in Kerala and Coimbatore district in Tamil Nadu. The basin has an inverted "L" shape with a maximum width at the intersection. The length-width ratio is 6:1. Most of the streams flow in deep gorges with steep valleys along the highlands of the basin. Coming out of the hills, the Periyar flows west and its basin occupies the northern part of Ernakulam district, covering the region from Neriamangalam through Aluva to Varapuzha and Munambam. The Periyar is an 8th order stream with considerable development of tributary network. The average drainage density of the basin is 2.46 km/ km2 with a total number of first order streams of 15,773. The total stream length inclusive of all orders in the basin is . The river originates from the high hills of the Western Ghats and the influence of tectonism can be evidenced from the stream pattern and presence of structural valleys. Forests occupy nearly (28%) of the basin area whereas cardamom and settlement with mixed tree crops occupy an area of and respectively. The basin is ecologically sensitive. Nearly 80% of the total area situated in the high ranges are susceptible to erosion and mass movements. Anamudi, at the highest peak in South India, is the highest point in the basin. Cardamom Hills The upper part of the Periyar basin extends across the Cardamom Hills. In the north, these hills extend up to the high Munnar saddle running east to Chokkanad Mala and further on to Kolukkumala on the eastern edge of the Ghats. In the south, the hills reach up to the westerly spur at Chokkampatti Mala. This section of the basin is divided into three parts. Source - Southern Cardamom Hills The southernmost part of the Cardamom Hills i.e. the source of Periyar River is a narrow valley extending south of Kumily. This is the southern extreme of the Periyar basin. It is less than wide and is about long. The upper catchments of Periyar extend as a wedge deep into the northeastern corner of the neighboring Pandalam Hills. This section of the Cardamom