General
Physiography
Kerala State is situated between 8 o 8' and 18 o 48' North latitude and 74 o 4' to 77 o 50' East longitude, along the windward side of the Western Ghats of Indian Peninsula . The State is located in the tropical region of Indian Peninsula and extends to an area of about 38863 km 2 , which accounts for about 1. 2 per cent of the total geographical area of the country. The State is bordered by Tamil Nadu State on its South and part of the East, Karnataka State on the North and part of the East, the Lakshadweep Sea on the West and the Indian Ocean along the South. The State has a total coastline of about 560 km and from sea level it rises to about 2694 m above msl.
Because of the location of the State along the windward side of the Western Ghats , it receives an average yearly rainfall of about 3000 mm, and the precipitations in the South-West and North-East Monsoon period, may go even up to 5000 mm, especially in the higher altitudes of Wayanad and Idukki plateaus. The average temperature of the State at 1ow and medium elevations ranging between 0-700 m is about 23 o C. Between 700 - 1400 m above msl, the temperature fluctuates between 16 and 23 o C and in the high altitude areas along the crests of the Western Ghats , it is about 15 o C during the coldest months. Above 1400 m elevation, the average temperature is even less, ranging from 13.5 to 16 o C, and it is in this zone that the shola forests, with similarities in species representation with the temperate Himalayan forests, are distributed in the State.
Physiographically, the terrain has three natural regions namely, lowlands, midland, highlands. A physiographic classification, identified mainly in terms of broad geomorphic surfaces and altitudinal characteristics, is also used in the parlance of geographers (CESS, 1984). It has five physiographic zones, namely, high ranges with elevation above 600 m, foothill zone between 300 to 600 m, upland regions between 100 - 300 m, midland between 20 - 100 m and coastal areas and low land below an altitude of 20 m.
Importance of Kuttanad
The Kuttanad landscape comprises around 1100 km2 of which about 304 km2 lies below sea level. The land which is presently inhabitated by human population, is developed by reclaiming the waterlogged areas over the years. Kuttanad is drained by a nerwork of rivers and man-made channels. The main feature of the drainage system is the Vembanad lake that was formerly a large lagoon. The tidal flow into this lake is controlled by a regulator at Thaneermukkom. This network of canals and bunds throughout its entire extent gave it the sorbiquet Holland of Kerala. The landform of Kuttanad comprises of Kayalnilangal (8100 hectares), Karinilangal (6,075 ha) and Karappadangal (42,505 ha). Kayalnilangal is below the sea level. Though the soil is acidic, if the saline intrusion is prevented, the area can be utilised for paddy cultivation twice in a year. Karinilangal is waterlogged and due to the presence of high acidity, this contributes only very little to the cultivable land. Karappadam is the land, which has been reclaimed over the years. North Kuttanad, mid Kuttanad and upper Kuttanad comprises the Karappadams.This is comparatively fertile and is less affected by saline water intrusion. North Kuttanad is prevented from salt intrusion by the Thaneermukkom Regulator.
The water inflow of Kuttanad is mainly controlled by four river systems originating from the Western Ghats region viz.,Meenachil, Manimala, Pamba and Achencoil, which ultimately drain into Kuttanad. Hydroelectric and irrigation projects in these rivers determine the water flow to the Kuttanad. The human interventions and resulting land use changes in the upstream of these rivers cause serious consequences in the ecological conditions of the downstream areas. The total basin area of these four rivers comes to around 5838 km2. The floodwater enter Kuttanad from the upstream catchments during the monsoon period. The flood water from these rivers carries considerable sediment load that spreads out on the lowland. During high floods water overflows bunds over to the roads and homesteads and cause serious havoc. Farming is the main occupation of the people of Kuttanad. Paddy cultivation predominates in the low land. Coconut palms are planted on bunds and reclaimed lands. The extent of coconut cultivation is increasing. Pepper, banana and yarms are also cultivated in certain areas. The reclamation of land for habitation and raising homestead cultivation has reduced the available are for floodwater storage, which results in the rise of flood levels. The problem of Kuttanad is mainly attributed to the mismanagement of its hydrological regime. When the development was underway, hydrological aspects were not given due consideration which finally resulted in its present ecological crisis.
The area suffers regularly from:
Flooding and salt water intrusion which limit the growing season to a few months.
Lack of drinking water in the dry season because of salinity intrusion, various types of pollution etc.
Lack of dry land to build settlements, leading to very high population densities on the reclaimed bunds.
Poor road network because of the number of criss-crossing water courses, leading to a dependence on water transport.
Reference:
State of Environment Report 2007, Vol 1, Kerala State Council for Science Technology and Environment.
Kerala has 44 perennial rivers, of which three are East flowing and the remaining 41 are emptied into the Lakshadweep Sea , along the western side of the State . Rivers are generally swift flowing having very steep gradients in their higher reaches. Absence of delta formation is characteristic of Kerala rivers. The general drainage pattern of these rivers is dendritic, although at places trellis, sub-parallel and radial occur. The segments of river courses are nearly straight, indicating structural control, coinciding with the prominent lineament directions (NW-SE and NE-SW). As per national norm (Rao, 1979), there are no major rivers in Kerala. The four medium rivers, namely Chaliyar, Bharathapuzha, Periyar and Pamba have a total drainage area of only 8250 km 2 with length 169 km, 209 km, 244 km and 176 km respectively. The length of rest of the rivers varies from 16 km to 130 km, with an average length of 62 km and total drainage area of 19,485 km 2 . The river flow is modulated by about 30 reservoirs, mostly located in highlands (KSLUB, 2002; CWRDM, 1995). There are two fresh water lakes in the State namely the Pookot and Sasthamkottah. The State is also having a total of 46.13 km 2 of estuaries and backwaters. The important backwaters are Vembanad and Ashtamudi lakes
Ten broad groups of soils based on morphological features and physico-chemical properties have been identified in Kerala (Anon, 1978). They are red soil, laterite soil, coastal alluvial soil, riverine alluvial soil, grayish Onattukara soil, brown hydromorphic soil, hydromorphic saline soil, acid saline soil, black soil and forest soil.
The major forest types represented in the State (Champion and Seth, 1968) include the dry deciduous, moist deciduous, semievergreen, evergreen and shola forests . Within these four major forest types are also several subtypes and derivatives, differing in species composition and vegetation characteristics
Almost 78 per cent of the total land area of the State is under agriculture and dwelling, and the remaining 22 per cent of the land is under forests and forest plantations. Quite obviously, the pristine status of nature is better protected only in a limited area, and that too in the higher altitudes, whereas, most of the remaining area of the State is subjected to degradation and transformations of various types.
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