Ways forward suggested

The Alumni Association of the College of Engineering, Guindy, discussed at a recent seminar the December floods. The newsletter of the Association reported that the Chief Guest, G. Ganapathy Subrama­nian, Former Engineer-in-Chief, PWD, and Consultant-WAPCOS-Chennai, spoke on what needed to be done, rather than looking at the past. Giving a background of the meteorological, topographical and hydrological features of the Chennai Metropolitan Area (CMA), the river basins and tanks within it, the influence of/impact on the Pallikaranai Marsh Land and the Backing­ham Canal, etc., he detailed how rapid urbanisation and encroachment, discharge of raw sewage/sullage, and dumping of solid wastes, illegal construction, etc., had degraded the entire system and suggested the following ways forward for the future:

– Proper planning and curbing of occupation of hydrologically sensitive areas
– Pre-monsoon cleaning and desilting of flood channels
– Flood-zone mapping of all the rivers for magnitude with various return periods
– Restoring the flood-carrying capacity of all the rivers
– Restoring and preserving the Pallikaranai Marshland
– Conducting hydraulic and hydrologic model studies and preparing rescue management plans
– Flood forecasting
– Restoration of macro and micro drainage systems
– Desilting of water bodies
– Linking storm water drains
– Beautification of lakes and maintenance
– Improvement of ecology
– Placing data on flow, water level, rainfall, etc., in the public domain
– Arming Government bodies with legislative powers to deal with encroachments
– Creation of a Disaster Management and Rescue Force
– Carefully planned and executed resettlement plans for people living on the river banks and right of way of rivers
– Linking of Backingham Canal to the sea near Oggium Maduvu
– Keeping the mouths of Kusasthalayar, Cooum, and Adayar rivers open to the sea at all times

Another speaker spoke of the need to shift the airport to Sriperumbudur in the context of the inadequacies of the secondary runway and its impact on the flooding and operations of the main runway at Meenam­bakkam. Jaya Priya Rajiv, postgraduate student in M.Tech (Planning), made a case for approaches that could encompass flood plains regulation, permeable roads, rainwater gardens, blue- green infrastructure, underground water storage, rain water capture and delayed drainage etc, citing similar measures undertaken successfully in other parts of the world. (Courtesy: AACEG News)

In the question and answer session that followed, the ­following points were stressed: the need for an overarching ­Authority to ensure a holistic approach in the framing and ­execution of the works, enhancing the capacity of the tanks in the region, recourse to flood forecasting models based on rainfall distribution in the zone of influence that could reduce the subjective element in decision-making, proper execution and upkeep of stormwater drains, need for posting of staff with adequate experience in sensitive posts, greater coordination between the Central and the State governments in the execution of works, and dissemination of flood warnings down the line in the various departments etc.

S. Suryanarayanan

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