Failure to desilt main water bodies in Goa could lead to widespread flooding, warns study

PANAJI: A research study conducted by the Mumbai-based think tank CPIE India (Centre for Promoting Indian Economy) over the last one month on lakes, rivulets, river beds, river banks and other water bodies in the coastal state of Goa has warned that 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 lake), 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.

According to Prof. Altin Gomes – who worked with the CPIE India on this study titled “Water bodies in Goa – a Crying Need”, 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 India 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 marine ecosystems.”

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

“But this is far 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 the desilting process itself, in the likelihood of floods and the impact of soil erosion in farmlands when floods hit due to excessive rainfall caused by Climate Change factors and Global Warming,” explains Gomes.

“Just like nullahs, storm water drains and other water bodies are cleaned up before the monsoons to increase their water carrying capacity, even rivers, rivulets, lakes and major rivers need routine desilting for various environmental and economic reasons,” explains Dr Naik.

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.”