JOIN USCatchment destruction worsens Cauvery crisis
The catchment of any river requires special treatment to maximise water holding capacity by roots of plants, reduce soil erosion and consequent siltation of reservoirs and Cauvery is no exception.
Catchment treatment always means taking up afforestation in denuded and barren areas and also soil moisture conservation works like check dams, gully plugging, nala bund etc. Catchment treatment also includes protection of flora and fauna and keeping fast changing land use pattern in check.
River Cauvery takes birth in Kodagu district of Karnataka in the centre of the Western Ghats. It is a hilly district with undulating landscape known for luxuriant tree cover. A major portion of the district provides catchment for Cauvery and its tributaries.
This catchment used to have one of the most magnificent dense tree covers on the land in the past. The French Institute, Puducherry has investigated the satellite imageries of the catchment in different years. Imageries of 1977, 1997 and 2007 have been compared and the loss of tree cover is seen as huge.
Loss of such wonderful tree cover deplete the water retention capacity of the area and during the rainy season more water flows with high velocity as runoff, carrying soil with it . This indirectly results in depleting the flow of water during summer months and siltation of reservoirs.
The investigation of French Institute has further revealed that the loss of tree cover was in non-notified forest areas and the area under coffee cultivation has gone up by 22% in this period of study. How did we lose tree growth from non-notified forest areas?
The tree felling on such land is regulated by Karnataka (Preservation) of Trees Act where deputy conservator of forests as tree officer is empowered to grant permission for felling of trees and his controlling officer is the chairman of the Tree Authority, where appeals are decided under the said Act. It can be inferred that forest officers have recklessly granted permission for felling of natural trees in the catchment of Cauvery for extension of coffee cultivation.
Revenue officers and forest officers have colluded and trees have been removed from Pysari and Bane lands as well, without properly determining the rights of an individual on such land. The confusion in land tenure in Kodagu is fully exploited and timber merchants have prospered.
Some forest land in the river catchment have been granted for lease for thousand years with a permission to remove natural tree growth and raising plantation crop of rubber etc. Besides, the Forest Department has also cleared the natural forests and raised monoculture of teak and other fast growing species for economically viable projects. Monoculture is again not conducive to retain water in the subsoil and maintaining the flow during summer months.
The Cauvery catchment does have stretches of grassy blanks interspersed with Shola forests. During the summer months, fire protection around Shola forests is very vital to keep the flow of water stream originating from these forests intact.
Repeated fire in the grassy blanks can scorch the Shola forests from all round, resulting in shrinkage of these forests. The flow of water originating from these streams depletes. The inflow in the reservoir during non-rainy season, therefore, diminishes. It is therefore necessary to preserve grasslands and Shola forests in the stretches of Brahmgiri sanctuary, Pushpagiri sanctuary, Bhagamandala, Talacauvery etc.
Rainfall pattern
Deforestation in the catchment has affected the rainfall pattern. We know that moisture laden air moving from the sea towards land causes rainfall in areas where low pressure is developed. It has been scientifically established that if this air passes over the forests, it gets sucked due to low pressure over these areas generally because of heavy transpiration losses.
Application of chemical and fertilizer to boost the agriculture and coffee production and discharge of industrial waste in the tributaries of the river, pollutes the water in a big way. Industries along the river and its tributaries discharge large quantity of effluents. Çauvery’s Noyyal tributary in Tamil Nadu is polluted by Tiruppur textile industry and use of the water for irrigating crops has resulted in damaging the fertility of the land.
We need to be guarded against it, as water is supplied for drinking in all cities, towns, villages in its command area including the cities of Bengaluru and Mysuru. Why should untreated effluents be discharged in the river?
Cropping pattern is changed with the availability of water. The farmers, who used to grow millet in their land, have switched over to high yielding variety of paddy and sugarcane. Since water is to be shared by the farmers in both Karnataka and Tamil Nadu, the administrations there must exercise some regulation and proper cropping pattern adopted in consultation with Union Ministry of Agriculture.
We, therefore, work for treating the catchment by planting barren and denuded areas with miscellaneous species and taking up soil conservation works, treat industrial effluents before discharge, regulate use of chemicals and fertilizers and cropping pattern for efficient use of water, regulate sand mining, etc.
(The writer is retired Principal Chief Conservator of Forests, Karnataka)