Streams

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 its 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.

The communities in the upper Nilgiris have historically used springs and wetlands as water sources, with streams being used for conveying sewage and other waste. Further downstream, where springs and wetlands are scarce, there is a greater dependence on stream water as the only perennial source of water. These communities are at the receiving end of contamination due to upstream activities.

Streams are also increasingly being tapped by private estates for irrigating tea plantations during the dry season. This results in competition for scarce water resources among estates and downstream communities, resulting in the latter being deprived of access to water. In Sigur plateau, the damming of water in the upper areas for power generation has resulted in streams running dry every year. The proliferation of borewells along with this lack of stream flows has resulted in depletion of groundwater. Most of the open wells and many borewells that the communities depended on for water supply are seasonal now forcing them to transport water at huge costs to meet their water needs. The maintenance of base flows in the Sigur river since last year is a step in the right direction not only for the people but also the wildlife in the region.


  • At 11 AM on 11th June, at UPASI in Coonoor a meeting is being held in which representatives from District Administration and various departments, prominent academic and research institutions etc. are expected to participate. The District Collector, The Nilgiris District would be the chief guest. The presentation to be made at the meeting is available here. The current version of the simulation model (work in progress) is available here for reference. The model file is developed in Matlab but can be run in Freemat as well. More documentation on the model and how to use it would be added shortly. Please give your valuable feedback in the comments section below.  

  • The project proposes to influence existing policies pertaining to, - Use of pesticides - Municipal sewage and waste disposal - Land use change, including planting of exotic species Downstream impacts on livelihoods and ecology: The Coonoor river will be taken up a case study. This will measure and prove need for conservation action and protection of upstream shola-grasslands and wetlands/swamps landscapes for downstream continuity of water resources for people and wild life and nature. Expected results will be highlighting using sample upstream – downstream landscapes / villages ecological benefits and primary services such as drinking water. The project will include quantification and valuation of hydrological benefits provided by upstream shola grasslands to downstream communities/landscape. The assessment would also gauge the impact of land use patterns/practices. The project is also aimed at bringing about a radical approach towards water issues and thereby starting the process of influencing policy change. The time frame of the project is 18 months. Given the time constraint it is not feasible to take hydrological measurements over different points of time to compare changes. The focus would instead be on developing a model that describes the effects of various factors on the state of the ecosystem from the point of view of hydrological services. One or more sub-basins would be chosen in the Coonoor area and a methodology would be developed to collect a mix of primary and secondary data and produce such a model for the Coonoor region. The various hydel projects in the Nilgiris would be tapped in addition to the water resources, forest and electricity departments for data routinely collected by them. Quantity as well as quality of water would be looked into. The output of the model would inform the policymakers as well as the general public and other stakeholders such as industry of the trends and order of impact on the water resources and the need for appropriate policy and action. Environmental Governance: The environmental governance is aimed at the local municipality and other relevant line departments and the District Administration for constructive discussions and proactive measure towards water conservation. This will include the forest department, municipality of Coonoor & Pollution control, water, agriculture, horticulture and land use departments, local elected representatives at Town Panchayat, Gram Panchayat, Municipality etc. They would be engaged with through one-on-one meetings, workshops and other rallying points around the theme of water conservation. Outreach and conservation action through the Bee Museum, Village Conservation Centres and the recently formed Nilgiri Natural History Society: There is a significant potential amongst community members and citizens of the Nilgiris to engage with and continue in this wide-open ended environmental education strategy. A module that has emerged after several stakeholder discussions and feedback will be tested in this phase and the findings from the study would be incorporated to strengthen the water conservation component. This component is aimed at generating a demand from the people, a pressure group towards policy changes in water resource management. It is also aimed at making people aware of the status of their water resources so that water conservation can be promoted. The NNHS is already engaging with people from various walks of life in Coonoor on issues of importance such as Human Wildlife Conflict. Keystone and NNHS would work towards engaging groups such as tea estates, Rotary/Lions clubs, citizens groups, in promoting the theme of water conservation. The Bee Museum is a resource center in Ooty that has grown from being a thematic resource centred on bees and honey to being an NBR Information Center in partnership with the Nature Conservation Foundation, Mysore. It is the focal point of outreach activities of Keystone and has been recently handed over to the NNHS as a base for its activities.  

  • The Nilgiris have seen a drastic change in land use pattern over the last century or so with shola forests and grasslands being replaced by monoculture plantations, habitations, farmlands etc. There is also an ever increasing population settled locally as well as a significant floating population that visits the Nilgiris for tourism. The pressure of all these factors affects the flow of water from the Nilgiris negatively. There has been some research in the past that has looked into these effects. 1. A study by Meher-Homji (1984) in the Nilgiris show a diminishing trend for the number of rainy days, but the conclusion is not highly affirmative since it compares a window of 4 years: 1886-1890 with another window of 4 years: 1978-1982. 2. A study by the CSWCRTI in the Nilgiris used a paired watershed study approach to look at the impact of replacing grasslands by Bluegum plantations (Sikka and Selvi, 2006). The study shows that this replacement resulted in reduction in water yield, decreased low flows and increased soil moisture losses. The reduction in water yield was 16% and 25% respectively in the first and second rotations. Such results have important implications when considered over a large scale, if such policies such as conversion of grasslands into new forest type are made. Therefore, conversion into any forest type might not yield desired results; at the same time the age of the forest and other components of the forest hydrology such as recharge into groundwater might need to be considered, which are ignored in this particular study. Recently, interesting work in the Western Ghats has been done under the IHP programme with collaboration with NIH and ATREE. One such work describes the unique nature of hydrogeology of the Ghats in Karnataka in which much of the runoff is in terms of subsurface storm flow through large pipe network just below the surface (Putty, 2006). To classify this as base flow wouldn’t be correct since the time span is very rapid. Similar observations have been made in CSWCRTI monitored watershed in Uttaranchal, eg the Salri watershed, wherein almost 50%-70% of precipitation is reported to be infiltrating. It would be erroneous to assume this infiltrated water as entering the groundwater table since much of it flow downstream immediately as subsurface storm flow component of streams. There is also attempt at modeling groundwater flows over a sub-basin level and simulating the impact on forest land due to pumping (Sekhar et al, 2007). It has been suggested through modeling that excessive pumping from agricultural land could lead to decline in groundwater levels in the Bandipur forest area. Given the scale of changes that have happened over the decades in the Nilgiris, prima facie it seems that massive changes in hydrological services would have occurred. It is therefore imperative that policy making is informed of the implications of such land use changes in a simple and accessible manner that is based on sound scientific method[1]. [1]          . Source: Krishnan, Sunderrajan. Forests and Hydrologic Rejuvenators: Compiling current debates to guide future action. 2008.