In deep waters
No river but carpet of weeds
Hundreds of creeks, streams, small and large tributaries join River Tungabhadra along its way. As the river enters the granite boulders of Hampi vicinity from plains, it becomes picturesque. Agricultural and industrial development along the river has changed the economy of the entire region.
Millions of people survive on this water source, directly or indirectly. Hence, River Tungabhadra is considered to be a lifeline of central Karnataka. As the water that flows from the mineral-rich Sahyadris, from a height of 1,198 metres, it has rich minerals and so, it is sweet to drink. Hence, there is a saying Ganga snaana, Tunga paana, which means that to get an eternal blessing, one has to dip into River Ganga and drink water of Tunga. A number of small and large dams have been built across the river in various places to enable people to have access to water for drinking and agricultural purposes.
Threats to aquatic life
Unfortunately, in the last few decades, the river has been polluted by various sources. Hundreds of villages, towns and cities release untreated municipal sewage directly into the river. Additionally, hundreds of small and large scale industries release effluents into the river directly without treating it. This amounts to billions of litres of sewage and effluents polluting the river and as a result, turning it into a drainage and dump yard.
A number scientific studies have been conducted about the pollution and water quality of River Tungabhadra. According to a 2007 study by S Manasi, associate professor at Institute of Social and Economic Change, Bengaluru, “Pollution by industries is a major source of water pollution across the basin. Major types of industries include iron and steel, paper and pulp, chemical and sugar.”
Another major menace to the river is by modern agriculture activities in the watershed area of River Tungabhadra. Tonnes of chemical fertilisers and pesticides are being used liberally for the cultivation of areca nut, paddy and many other crops that grow in its watershed area. The rainwater washes all chemical residues into the small streams that join Tungabhadra. All these pollutants have heavy metals, poisonous chemicals and salts that kill the fragile aquatic flora and fauna.
The presence of nitrates, phosphates, sulphates, carbonates, bicarbonates, magnesium, sodium and potassium, etc in huge quantities from effluents also contribute to the river’s pollution. This has led to the river’s ecosystem being altered. The excessive accumulation of these pollutants results in uncontrolled growth of water hyacinth in the river.
The free floating weed is believed to have invaded the Indian freshwater systems in the early 19th century, after it was introduced as an ornamental garden plant for its beautiful purple inflorescence. It grows up to three feet in height and has thick waxy round leaves which emerge over the surface of water. The plant’s bulbous stalk helps it to float.
The aquatic plant is native to the Amazon basin and is considered to be an invasive species outside its region. It a fast growing hygrophyte that propagates by its stolons (stem) and covers the entire surface of water in short period of time. It grows so rapidly that a single plant can cover about 600 sq metres in a year! The thick carpet of water hyacinth does not allow sunlight to pass through it. The lack of sunlight prevents the photosynthesis of submerged aquatic plants. The lack of photosynthesis results in low or absence of dissolved oxygen. This ultimately results in the death of aquatic fauna.
An ecosystem on the wane
The free floating unicellular phytoplankton and algae die due to the lack of sunlight and as a result, begin decaying. This results in a strong, unpleasant smell emanating from the water. The aquatic wildlife like fishes, crustaceans, amphibians and others begin to diminish from the water body where water hyacinth occupies. Due to the non-availability of fish and other prey base, animals dependent on the water source, such as the crocodiles and otters, starve to death. The excessive growth of water hyacinth also results in silt formation and ultimately resulting into rivers and lakes vanishing.
About a decade ago, there was no trace of water hyacinth in River Tungabhadra but it was seen here and there in the still waters of the river and was being washed away during the flood and when the gates of the Tungabhadra Dam opened. Due to scarce rains in the last three years, flooding has not happened in the river and the dam gates have not been opened. So, the accumulation of water hyacinth over the period turned the blue river into a green carpet of vicious weed.
The 35-km Tungabhadra Otter Conservation Reserve (TOCR), from Tungabhadra Dam to Kampli, was harbouring a good number of smooth-coated otter, mugger crocodile, four species of rare turtles and hundreds of species of fish, some of which are listed under vulnerable, endangered and near-threatened under the International Union for Conservation of Nature (IUCN). But most of the pools in the TOCR area are now covered by the water hyacinth, which in turn has killed the micro ecosystem. When the fish was killed, crocodiles and otters abandoned the pools staking their life in alien locations.
The growth of the weed in the pools and ponds has left the fishermen community struggling for their livelihood. Areas where the water hyacinth grows in abundance are the favourite breeding grounds for mosquitoes, hence diseases like dengue are spreading along the riverside.
It seems that the authorities and elected representatives have forgotten the importance of the river and its ecosystem for sustainable living.
With the river’s water contaminated with pollutants and the water coming down, those engaged in livelihoods such as farming and animal husbandry have experienced losses. Hospet-based voluntary organisation, Society for Wildlife and Nature (SWaN), began working with the government and other civil society organisations to check the release of municipal sewage and industrial effluents into the river. Using the Mahatma Gandhi National Rural Employment Guarantee Act (MNREGA) fund, local fishermen were employed to remove the weed from the river.
It is just a beginning. A lot more needs to be done and the government has to take a serious note of saving rivers and adopt permanent solutions to prevent the choking of the rivers by weeds and pollutants. To make the process more participatory, there is also a need to create awareness among the people from different walks of life. Rivers are the cradles of civilisation and it is the responsibility of human beings to ensure that they spring back to life.