Kerala is a unique land with a unique climate. Very high blue mountains on the West. Undulating hills and valleys on their laps with 64 fast flowing rivers falling into lagoons, which make the National Water Way III. And the world famous beaches on the seacoast. Kerala has two monsoon seasons viz. the South West and the North East. The proximity of mountains and sea and the long monsoons create a tolerable temperate climate in this verdant paradise.
Hills & Valleys
This strip of land on the eastern edge, close to the Ghats, comprises of steep mountains and deep valleys, covered with dense forests. Almost all the rivers of the state originate here. Tea and coffee estates have cropped up in the high ranges during the last two centuries.
In this central region, the hills are not very steep and the valleys are wide. The valleys have been developed as paddy fields and the elevated lands and hill slopes, converted into estates of rubber, fruit trees and other cash crops like pepper, tapioca, etc.
This strip near the coastline, is comparatively plain. Extensive paddy fields, thick groves of coconut trees and picturesque backwaters, interconnected with canals and rivers, are the features of this region. In the southern and northern parts of the state, the coastal belt also has some hills and valleys.
Backwaters & Rivers
Backwaters: The backwaters are a peculiar feature of the state. Canals link the lakes and backwaters to facilitate an uninterrupted inland water navigation system from Thiruvananthapuram to Vadakara, a distance of 450 kms. The Vembanad lake stretching from Alappuzha to Kochi is the biggest water basin and is over 200 sq.kms. in area. Water-logged Kuttanad alone forms more than 20 per cent of India's total length of waterways.
There are 44 rivers in the state, of which 41 originate from the Western Ghats and flow towards west into the Arabian sea. Three tributaries of the river Cauvery originate in Kerala and flow east into the neighbouring States. These rivers and streams flowing down from the Western Ghats either empty themselves in to the backwaters in the coastal area or directly into the Arabian Sea.
As the Western Ghats are nowhere more than 120 kms from the sea, all these rivers are comparatively short.
The important rivers from north to south are; Valapattanam river (110 kms.), Chaliar (69 kms.), Kadalundipuzha (130 kms.), Bharathapuzha (209 kms.), Chalakudy river (130 kms.), Periyar (244 kms), Pamba (176 kms), Achancoil (128 kms.) and Kalladayar (121 kms.). Other than these, there are 35 more small rivers and rivulets flowing down from the Ghats. Most of these rivers are navigable up to the midland region for country crafts which provide a cheap and reliable transport system.
Kerala receives a fairly good annual rainfall varying from 1250 to 5000 mm.The normal annual rainfall of Kerala is 3107 mm.(national average is 1197mm). The State has the benefit of the South West and North East monsoon. Although, quantum wise the rainfall received is fairly high, its distribution shows wide temporal and spatial variations. On an average the number of rainy days is in the range of 120-140 in a year. The annual yield of water in Kerala in a normal year is around 7030 crores cubic metres. The utilizable water resource is around 4200 crore cubic metres. The highest rainfall occurs in the high ranges of Idukki district where it exceeds 500 cm.
This diversity of rainfall makes it very cold high up in the mountains, while lower down at an elevation of 1000 to 1500 meters, a bracing climate is experienced. In the plains and lowlands, it is generally warm and humid. Maximum temperature is around 36.7 degree C and the minimum is about 19.8 degree C