Contamination, pollution and deterioration in water quality of Goan water bodies due to non removal of sediment: Experts

PANAJI: The evaluation of various water bodies in Goa by the Mumbai-based think tank CPIE India (Centre for Promoting Indian Economy) in association with the Raksha Hospital Research Forum – a part of the Raksha Multispeciality Hospitals group has found that the failure to desilt and remove accumulated sediment, fecal matter and other non-biodegradable debris from water bodies in Goa, including lakes, ponds, rivulets and rivers is leading to water contamination, pollution of banks and overall deterioration in water quality of water bodies in the State.

An evaluation paper titled “Water bodies in Goa – a Crying Need”, which is part of the research study has found that “regular sediment removal and desilting is necessary to maintain the balance of the ecosystem as failure to do so increases the percentage of harmful microorganisms found in fecal and other decaying matter leading to contamination of water bodies, making the water unsuitable for human skin and even swimming in such water could result in various skin infections and diseases,” Dr Pranav Kabra chief consultant for the research said, adding that sewage-derived fecal coliform bacteria content in many water bodies in Goa is higher than national or internationally accepted standards.

Dr Kabra’s statement assumes importance, given that as early as 2011, the National Institute of Oceanography had flagged all of Goa’s coastal waters and rivers as contaminated with fecal coliform bacteria at levels much higher than acceptable or permissible.

The CPIE India research was conducted a little over a month on water bodies, lakes, rivulets and river beds and river banks in the coastal state of Goa has warned that besides contamination, failure to desilt such water bodies could eventually lead to widespread flooding in villages and even towns in Goa at a later date due to Climate Change-related phenomena.

Several water bodies in Goa including small ponds, lakes (for example in Curtorim), rivulets and even river beds are in drastic need of desilting as the silt build up in these water bodies has greatly reduced the overall carrying or storage capacity of the basins over the years and led to massive pollution of such water bodies, Dr Pranav Kabra informed.

According to Prof. Altin Gomes – who worked with the CPIE India on this study, locals and some environmentalists in Goa are against the concept of desilting lakes, river beds and ponds and very often mix it with another technical concept called dredging.

The main opposition to desilting in Goa, is the imagined or perceptional damage that could be caused to the environment, including marine flora and fauna and piscine life.

However, according to Dr Sadashiv Naik, an environmental scientist, associated with a premier fisheries’ institute in the country who also worked on the CPIE study of Goan water bodies, “there is no perpetual damage to any environmental or marine ecosystems and in fact, scientific desiliting is highly beneficial to revive marine ecosystems.”

Villagers, panchayat members and some environmentalists raise a hue and cry when desilting activity in Goa is carried out in water bodies on the ground that the natural flora and fauna on the bed will be destroyed.

“But this is far away from the truth as desilting only removes accumulated silt and does not disturb the bed rock. Further, while the benefits of desilting are manifold, the plant and piscine life regenerates within a few months, opined Gomes, concurring with Dr Naik on the subject.

“In fact, failure to desilt can cause far much more harm than desilting itself, in the likelihood of floods and the impact of soil erosion in farmlands when the floods hit due to excessive rainfall caused by Climate Change factors and Global Warming,” explains Gomes.

Desilting is often mixed up with dredging due to the lack of knowledge in the difference between the two terms and methods.

Rajesh Shetye, another environmental scientist from Mumbai says, “dredging refers to the clearing of the bed of rivers and waterbodies by scooping out mud, rocks, weeds and unwanted materials including non-biodegradable garbage.”

Elaborating on the difference, Gomes explains, “desilting refers to the removal of earthy materials, fine sand, dirt, non-biodegradable matter, garbage etc., carried by running water particularly during monsoons and deposited as sediment. Due to the deposition of this sediment, problems like choking, reduction in water depth, reduction in basin width and other similar factors impact the overall environmental situation.”

Regular desilting and scientific sediment removal does not destroy marine, aquatic and piscine life in water bodies, but greatly helps in reducing pollution and presence of harmful microorganisms in the water, Dr Kabra stated.