And listless flows river Cauvery

And listless flows river Cauvery

Illegal sand mining is threatening the flora and fauna along the river basin in Karnataka

Bhargavi Kerur. Bangalore



Bangalore could have been on the banks of river Cauvery if not for human intrusion and rapid pace of development that destroyed the vegetation on its banks, a study conducted by the Geological Survey of India had pointed out a decade ago. Researchers now suspect that this intrusion has altered the course of the river.
But now, the river is again being threatened in interior Karnataka due to disturbance in vegetation, which is being caused by illegal sand mining, cattle grazing in restricted areas and conversion of the areas into tourist spots.
A team of researchers at the department of environmental sciences, Bangalore University, headed by RK Somashekar, the head of the department, assessed the damage to the vegetation on the river's banks, which is threatening the endemic flora and fauna.
"This is the first ever attempt to assess the disturbance of riparian vegetation along the 165-km stretch of the banks of the river from Talacauvery to Mekedaatu," Somashekar said.
The earlier studies conducted by various researchers had indicated destruction of vegetation along the banks of river Ganges (80% destruction) and Chalakkudy river basin in Kerala. The present study has been conducted to assess the diversity, composition, and similarity of tree species along river Cauvery in Karnataka.
"For vegetation sampling, a total of 27 plots were selected along a 133-km stretch of the river. All the study sites experienced various types of anthropogenic activities, which are affecting the vegetation distribution of the riparian zone. Although several study sites are located in the protected areas of the Cauvery Wildlife Sanctuary, the intensity of anthropogenic activities in those regions are found to be higher due to the presence of tourism centres," said the co-author of the study, C Sunil. The remaining stretch will be studied further, he added.
"Though the Cauvery basin is a well-protected area, grazing of thousands of heads of cattle their every day has become the main component of disturbance. People's intrusion in the form of tourists and their activities like mass cooking during festivals have affected the soil quality," Sunil said.
Since 70% of the vegetation has been disturbed, the canopy of flora that supports the regeneration of the forest has shrunk leading to speedy disappearance of the tree system, he said.
Several sites showed high vegetation density in disturbed areas due to the invasion of exotic species like Pithecoellobium dulce and P pinnata, and plantations like Cocos nucifera, eucalyptus, and areca catechu by farmers. These have stressed out the species diversity in these zones, resulting in the loss of dense vegetation, the study said.
Sand mining has resulted in the disappearance of native species to an extent, as it obstructs the flow of surface water by altering the channel morphology. The study points out that intense biotic pressure around the river basin have negatively impacted the original riparian forest, which is very important as it is rich in bio-diversity. Most endemic species in the riparian zone have been replaced by alien species. Conservation of riparian vegetation in this zone acts as a corridor for wildlife movement, and it also supports the livelihood of tribals, fishermen, and other locals. A minimum width of riparian vegetation in an agro-ecosystem zone is very essential to maintain the quality of river water and also for biological conservation of species.
Now, the researchers are planning to propose a policy change to restrict cattle grazing and human intrusion and ban sand mining for conservation of the zone.