Kerala   

Check-dams: study for a cautious approach

Staff Reporter

It proposes a detailed analysis of their impact on sediment and nutrient flow towards coastal regions

ECOLOGICAL QUESTION: A check-dam at Lakkidi during monsoon.

PALAKKAD: A study on the ecological changes in the upstream and downstream areas of the Bharathapuzha has sought a precautionary approach towards building more check-dams on the course of the river.

The two-year study was conducted by a team headed by Biju Kumar, Research Department of Zoology, NSS College, Pandalam, on the ecological changes in the upstream and downstream areas of Lakkidi and Peringottukurissi check-dams.

The report, submitted to the Department of Science and Technology of the Union Government, recommended a detailed study on the subject.

The report said, ``Just like large dams, check-dams also facilitate tapping sediments and nutrients and deny their transport to downstream areas and coastal region. In general, the hydrological features of the upper reaches of the check-dams are comparable to that reported from the large reservoirs of Kerala. Hence a hypothesis was forwarded that the reservoirs of check dams, in longer time periods, may function just like reservoirs of large dams, gradually changing the biotic communities which are adapted to live in stagnant water.''

The study proposed a detailed investigation of the impact of check-dams on the sediment and nutrient flow towards the coastal regions. It is important to note that the Ponnani beach is now protected by a seawall as a result of heavy beach erosion.

The study noted that accumulation of more sand in the upstream area and consequent illegal sand-mining affected the stability of check-dams. The frequent collapsing of check-dams in the tributaries located in the upper reaches of the Bharathapuzha would be due to rampant sand-mining from within the upstream area of check-dams and unsuitable localities selected for check-dam construction.

The study recommended the immediate banning of sand-mining from the reservoirs of check-dams. The lesser diversity of benthic organisms recorded from the riverbed is believed to be due to rampant sand-mining. Migrating marine fishes (nearly 12 species) were recorded only up to the downstream area of the Lakkidi check-dam. Fishes that restricted themselves to the upper reaches of the check-dams were represented mainly by carps, such as cyprinus, catla, rohu and mrigal grown in the large reservoirs of Malampuzha and Walayar located in the upper reaches.

In the light of the findings, the study proposed a precautionary approach before constructing a series of check-dams in the river, as it might deny freshwater, nutrients and sediments to the lower reaches, even though it was a fact that check-dams enhanced groundwater replenishment in the nearby areas.

The study also recommended an ecosystem management approach for the conservation of the Bharathapuzha, taking into account water conservation in watershed areas of the river, forest protection in the catchment areas, biotic and abiotic interactions and population and community structure within the river.

The study said that though hydrological parameters of the Bharathapuzha recorded values within the standards stipulated by the World Health Organisation and Indian standards, presence of large numbers of faecal coliform bacteria, Escherichia coli, particularly in the upstream areas of check-dams during summer, was a matter of concern, as it indicated faecal pollution. Coliform bacteria were rod-shaped microscopic organisms inhabiting the large intestine of mammals and their presence in water indicated contamination with human faecal matter.

Thus the water from the river, particularly from upper reaches of check- dams, should be used for drinking only after treatment — chlorination or boiling, the study recommended.

Printer friendly page  
Send this article to Friends by E-Mail

Stories in this Section

Rebel DIC leaders toughen stand on merger issue
Gender cells to be set up in Indian embassies
Documenting the life of a great stage artiste
Check-dams: study for a cautious approach
An evening of camaraderie
Thousands partake of Ashtami Rohini feast in Aranmula temple
Bouquets for the police
Central Social Welfare Board sanctions 250 additional crèches for State
Project to preserve legacy of Kodungalloor
Brahmana Sabha meet to discuss reservation
Tension prevails near Thalassery town
Chandy: ensure admission to all
Anthrax scare in Periyar Tiger Reserve
Briefly

Copyright © 2006, The Hindu. Republication or redissemination of the contents of this screen are expressly prohibited without the written consent of The Hindu