Pollution in small dams misjudged in India

Hyderabad: A first-of-its-kind research article said small dams across rivers have been misjudged to not have environmental impact as opposed to large dams in India. The article focuses on the Western Ghats.

The article was written by PhD student and graduate assistant Suman Jumani of the soil and water sciences department of the University of Florida in collaboration with Wildlife Conservation Society, ATREE and National Centre for Biological Sciences.

The report states: “Small hydropower projects have disrupted the longitudinal, lateral and vertical connectivity of rivers, altered physico-chemical characteristics, blocked sediment and nutrient transport, obstructed fish migration, and encouraged fish invasion.”

Two dammed tributaries and one undammed tributary of the Nethravati river in Karnataka was selected for the study.

Flow alterations were caused by small dams which caused the width and depth of the streams to be diminished drastically.

Lead author Jumani said, “The report talks about how dewatering causes community shifts by selectively favouring “eurytopic” fish which can tolerate ecological changes over “rheophilic” fish that are adapted to flowing river waters. The varying flow also causes decline in fishery yields.”

Speaking about displacement, Ms Jumani told this newspaper: “There have been a few instances where small hydroelectric projects (SHPs) have caused significant submergence leading to rehabilitation activity. For example, the allotted Kukke Stage-1 SHP on the Nethravti river would submerge over 700 acres of forest and agricultural land.”

With reduced stream flows, water temperatures would soar higher, and dissolved oxygen levels would fall lower.

“We collected fish from the dammed and dammed parts of the Nethravati river and identified the same standard taxonomic keys. We knew that the chemical and biological process on which the fish are dependent on would alter in case of SHPs,” she said.

“More generalist and not specialist species of fish that are unique to rivers were found with native species being driven to extinction,” she said. She also stated that fish species’ richness can bounce back with flow restoration.

“By restoring river flows, we reduce habitat fragmentation and allow sediment, nutrients and aquatic plants and animals to move freely,” Ms Jumani said.

The tagline, “If you can’t reuse it, refuse it” has gone viral with a call for citizens to be alert to ensure that water bodies are safe. With more plastic than fish is expected in oceans by 2050, a global attempt is being made to curb marine pollution.

Low prices make plastic a top choice

World Environment Day stresses the theme Ban Plastic Pollution, targeting one-time usage products made of plastic such as plastics cups, bottles, spoons, forks and straws among others. These items are mostly often found in eateries and have an adverse effect on one’s health.

Most of these items end up in the sea or landfills. Mr Anmol Roy, an environmentalist said, “Despite the invention of wooden spoons and even spoons that are edible after one’s meal, plastic is still the top most choice because of its disposability and the low cost. Unless the government bans items such as these, no action will be taken. Plastic bags are not the only items that are a bane on the environment but are the sole focus of officials.”

Medical experts state that the ill-effects of plastic, especially when plastic packaging comes in contact with hot food on one’s health, is immense.

Dr T. Unnikrishnan, a general physician, said, “As per recent medical studies, the leaching of plastic components and chemicals increases by 50 per cent if we add hot food or water into a bowl or glass. Even “microwave safe” containers leach chemicals.”

He said plastic that accumulates in the body over time cannot be removed. It can also be carcinogenic. “We should avoid plastic for our health just like for the environment.”