Conolly canal harmful to Kottooli wetland ecosystem, finds study

A research study by a husband-wife duo, both professors, one at the Indian Institute of Management, Kozhikode (IIM-K) and the other at the National Institute of Technology, Calicut (NIT-C), has revealed that rapid urbanisation in Kozhikode city has led to the extensive destruction of the Kottooli wetlands, a proposed Ramsar site, a wetland of international importance under the Ramsar Convention of 1971.

Deepak Dayanithy, a professor in strategic management at IIM-K, and Anjana Bhagyanathan, a professor in landscape architecture at NIT-C, have published their study in the journal Area of the Royal Geographical Society. They pointed out that contrary to popular belief, the Conolly Canal was not beneficial to the ecosystem of the Kottooli wetlands.

“The outflow of water from the wetland into the canal has caused an overall reduction in the water level, which in turn resulted in total wetland area loss. This created dry areas within the wetland, thus fragmenting it, and loss of ‘core’ areas that are important for hydrological and biological characteristics,” said Ms. Bhagyanathan. The canal also caused loss of agricultural land to a great extent.

“The link between Kottooli wetlands and Kallayi rivermouth through the canal resulted in backflow of brackish water into the wetland during high tides. Parts of the wetlands used for paddy cultivation, protected from saline water intrusion by sluice gates, were rendered uncultivable after the system failed in 1914. This loss could have played a part in the intensification of wetland conversion,” said Mr. Dayanaithy, adding that the canal also contributed to the depletion of groundwater, pollution and saline intrusion in the area.

The wetland became two fragments due to the canal construction and the spoil bank resulted in high embankments, and thus a transportation line that later developed into an urban growth generator. Over the last fifty years, the western segment of the wetland was filled for various purposes while the eastern spoil bank also widened. The Sarovaram Biopark, set up more than a decade ago, ended up conserving 12.86% of the wetland on the eastern side of the canal while the remaining part continued to be encroached upon. The construction of National Highway 66 has further led to the fragmentation of the wetland.

“Based on the development plan for Kozhikode for 2035, 10.45% of Kottooli wetland has been designated for tourism promotion. The wetland patch fragmented by NH 66 is designated as a mobility hub, with a proposed canal connecting Sarovaram Biopark and the mobility hub. There are also expansion plans of Conolly Canal into an inland navigation canal which entails further widening and deepening, resulting in more harm to the wetland,” Ms. Bhagyanathan explained how further urbanisation could affect the wetland.

The researchers have suggested delineating the actual wetland extent as a collaborative effort among hydrologists, ecologists, biologists and urban planners as the first step towards proper conservation of the wetland. “Creating a pedestrian path around the wetland will ensure that further encroachments do not occur. Besides, the wetland system needs to be allowed to restore itself by non-interference,” said Mr. Dayanithy, adding that it would address flooding and water scarcity in the city.

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