The Nilgiris, Blue Mountains of South India, is located at the junction of the Eastern Ghats and the Western Ghats, the two prominent mountain ranges that run almost parallel to the coastlines of Peninsular India. The district is located over an elevation range of 1,000-2,636 m above sea level, comprising hilly peaks, plateau and lower plateau regions - most of the settlements are located in the latter two elevation ranges. The district is home to a number of indigenous communities and they include the Todas, Badagas, Kotas, Kasavas, Irulas, Kurumbas, Jenukurumbas, Mullu Kurumbas, Bettu Kurumbas, Kattunaickens, Paniyas, Mandadan Chettis and Wynaadan Chettis. Water resources in the hill district of the Nilgiris, play a crucial role not for drinking and other uses to the rural and urban communities in the district, but also serve as the upstream source to four river basins serving the states of Tamil Nadu, Karnataka and Kerala. The water resources of the district are used for power generation and account for more than a third of total hydro-power generated in Tamil Nadu. Water as a natural resource plays a vital role in the ecology and economy of the district - be it in the large scale hydro power, the tea estates or in the forest dweller’s livelihood system. The Nilgiris is the source of two main river systems - the Bhavani and the Moyar, which comprise several streams emerging from high altitudes and flowing down to the Cauvery basin in Tamil Nadu. The Nilgiris is home to unique wetlands that are the source of sustenance of numerous animals and human communities. Wetlands are among the more important reservoirs of biodiversity that nature has painstakingly crafted over millions of years. Wetlands are highly productive and are cradles of biological diversity, providing the water and primary productivity upon which countless species of plants and animals depend for survival. They form refuge areas in times of drought, provide important breeding and nursery areas for a large range of animals.
Content about climate
The Nilgiris as a region can be divided into three strata of upper, middle and lower altitudinal zones. Each has a distinct vegetation and supports a variety of life forms and activities.
The Nilgiris district can be divided into four basins
Moyar Basin and its 24 rivers - draining mainly into the Bhavani reservoir as water supply for irrigation and drinking water in Tamil Nadu
Bhavani Basin and 26 rivers - draining again to the Bhavani reservoir along the district boundary and onwards again into the Tamil Nadu plains
Both the above basins finally feed into the Cauvery river basin.
Kabini basin and its five major rivers drain into Karnataka
Chaliyar basin and its eight rivers feed into Kerala
Inspite of 1800-2000 mm annual average rainfall, the number of rainy days has reduced drastically. Erratic and unpredictable rains have changed the water budget and utilization pattern. Water enterprises, such as private water tankers have boomed in this district.
There is a crucial linkage between Shola patches (endemic montane forest-type which occur in this region) and water resources availability. Wherever Shola forests exist, existence of water source is assured.
Large Government Water Schemes of the TWAD Board basically tap springs and infiltration systems and not ground water resources. Wells are built in swamps and marshes so that percolation from springs around the well also take place. Feeder pipelines from other springs are also brought to the well. These springs are found in various altitudes. Local land use adjacent to these water bodies is critical in maintaining year round water flow. Several spring sources have dried up or the flow has drastically reduced due to land use changes or development works (revetment walls, road enlargement, check dams, etc.). Encroachments (very common) have destroyed water bodies as they have been converted for agriculture or tea thus blocking spring routes. In marshy environments, it is important to keep the passage of flow open - this is the key to wetland management, but unfortunately decision-makers perceive these areas as vacant land for further development works.
There is field data to show that rains are failing both as the annual average and the number of rainy days. This has severe negative consequences on this fragile hill district - the livelihood of people, the plantation & agriculture economies and the ecology.
Geologically the Nilgiris belong to the Archean continental landmass of the Indian peninsula, composed of pre-Cambrian, mainly metamorphic rocks (gneisses, charnockites, and crystalline schist). Due to continental drift of the “Indian shield” which until late Jurassic times was a part of the ancient Gondwanaland – and coincident with the Himalayan orogenesis during the Cretaceous and Tertiary periods, geotectonic movements in the southern Deccan resulted in its fragmentation and in vertical dislocations along fault lines that are oriented in three main directions, viz. NNW-SSE, NE-SW and W-E, and that recur in the morphological boundaries as well as in the courses of many streams and rivers of the Nilgiris. Thus, the triangular-shaped mountain block of the Nilgiris was formed by the phase-wise uplifting of a portion of the Deccan. This horst is almost entirely made up of more or less garnetiferous, acid hypersthenic charnockites (Holland 1900) with a general NE-SW to ENE-WSW strike of foliation (Eastern Ghats trend) and traversed by doleritic and quartzite dykes. It is slightly tilted towards the east – like the entire Deccan Plateau – and has a base size of roughly 2400 square kilometers, of which 40 % rises above 1800 meters in the central Nilgiris Plateau (which falls off steeply on all sides). It culminates in Dodabetta, or “big mountain” with 2636 m elevation above mean sea level. It is the close spatial association of two contrasting morphological zones or relief types – the “mature” landforms of the elevated plateau and the “juvenile” Sigur, Pykara and other, minor rivers and streams, some of which have been dammed up during the past five decades. While the first, uppermost level has been designated Dodabetta landforms, the second and third together represent the Ootacamund landforms (Pardhasarathi and Vaidyanathan 1974). All three can be identified as fossil, disintegrating relict landforms showing little, if any, morph dynamism of the kind responsible for their original formation and similar to that still active on the Mysore Plateau and on the Coimbatore Plains. Under present climatic conditions and due to upstream migration of nick points of stream profiles as well as the deforestation and tillage of large tracts of land, linear erosion generally prevails over denudation processes. This is increasingly so towards the edges of the plateau where numerous streams and rivers leave the upper Nilgiris in torrential rapids and picturesque cascades, with heights of up to 120 m, which emphasize the youthfulness of the Nilgiri mountain block as a morphological unit.
Geologically the Nilgiris belong to the Archean continental landmass of the Indian peninsula, composed of pre-Cambrian, mainly metamorphic rocks (gneisses, charnockites, and crystalline schist). Due to continental drift of the “Indian shield” which until late Jurassic times was a part of the ancient Gondwanaland - and coincident with the Himalayan orogenesis during the Cretaceous and Tertiary periods, geotectonic movements in the southern Deccan resulted in its fragmentation and in vertical dislocations along fault lines that are oriented in three main directions, viz. NNW-SSE, NE-SW and W-E, and that recur in the morphological boundaries as well as in the courses of many streams and rivers of the Nilgiris.
Thus, the triangular-shaped mountain block of the Nilgiris was formed by the phase-wise uplifting of a portion of the Deccan. This horst is almost entirely made up of more or less garnetiferous, acid hypersthenic charnockites (Holland 1900) with a general NE-SW to ENE-WSW strike of foliation (Eastern Ghats trend) and traversed by doleritic and quartzite dykes. It is slightly tilted towards the east - like the entire Deccan Plateau - and has a base size of roughly 2400 square kilometers, of which 40 % rises above 1800 meters in the central Nilgiris Plateau (which falls off steeply on all sides). It culminates in Dodabetta, or “big mountain” with 2636 m elevation above mean sea level.
It is the close spatial association of two contrasting morphological zones or relief types - the “mature” landforms of the elevated plateau and the “juvenile” Sigur, Pykara and other, minor rivers and streams, some of which have been dammed up during the past five decades.
While the first, uppermost level has been designated Dodabetta landforms, the second and third together represent the Ootacamund landforms (Pardhasarathi and Vaidyanathan 1974). All three can be identified as fossil, disintegrating relict landforms showing little, if any, morph dynamism of the kind responsible for their original formation and similar to that still active on the Mysore Plateau and on the Coimbatore Plains. Under present climatic conditions and due to upstream migration of nick points of stream profiles as well as the deforestation and tillage of large tracts of land, linear erosion generally prevails over denudation processes. This is increasingly so towards the edges of the plateau where numerous streams and rivers leave the upper Nilgiris in torrential rapids and picturesque cascades, with heights of up to 120 m, which emphasize the youthfulness of the Nilgiri mountain block as a morphological unit.
Water from the upper areas flows through diverse landscapes, bringing with it a complex interaction and dependence. This is probably the only district where so many aspects of natural resources are linked in such a tight space. Spatial-temporal blocks exist, where cultures converge like the Badagas-Todas-Kotas in the upper areas, the Irulas-Kurumbas (in the lower areas), the urban and migrant population in the middle elevations. Each of these communities has a unique approach to water systems. Traditional management and indigenous knowledge have been eroded to a significant extent. Government power generation projects have also manipulated water systems. Government water supply and maintenance through different mechanisms and devices, have made forays into traditional systems of management, all not necessarily beneficial.
