Nandkumar M Kamat
After Chennai floods smart journalists rushed to have a look at how the city appeared 15 years ago in images available on Google Earth. They were astounded to see the massive reclamation of original water bodies that provided capacitance against flooding. A similar exercise can be undertaken using Google Earth to show how Panaji would appear when it floods.
Chennai flooding is a wakeup call for Panaji and similar towns like Mapusa which are simply inviting flooding by way of filling surrounding wetlands and low lying paddy fields in the name of infrastructure and urban development. No lessons have been learnt from the flooding at Guirim as Mapusa aims to engulf Guirim, Parra and Bastora.
Both Goa and Tamil Nadu are heavily urbanised states. Both Chennai and Panaji are coastal towns with creeks. Chennai is 375-year-old and Panaji is nearing 175. But, Chennai gets much less rainfall than Panaji, about 140 cubic metres per year. Most of it occurs due to north east monsoon. Chennai got 1024 mm rain during November and 300 mm on December 1.
It was a disaster because the city could not drain the rainwater. The intensity of rain was sometimes 50 mm per hour which means fifty million litres of water being deposited over a hectare per hour. Compare this with the capacity of the new sewage treatment plant of Panaji of just 12 million litres per day. It just overflows during the monsoon. Chennai did not flood because of heavy rains.
The damage due to floods will cross Rs ten thousand crores. Insurance costs have been estimated to cross Rs 2000 crores. Central government will have to release more than Rs 5000 crores. If that is the price Chennai paid for development then it is perfect example of unsustainable urban planning – ecological, hydrological and environmental. Panaji is foolishly imitating Chennai.
Chennai’s had many lakes and marshes, which were reclaimed for construction activity. IT Corridor of Velachery, Pallikaranai and Old Mahabalipuram Road destroyed more than 5,550 hectares of wetlands. One report says Chennai lost 300 natural water bodies in the process of urban development. Journalist Nityanand Jayaraman reported on the website scroll.in: “Virtually every one of the flood-hit areas can be linked to ill-planned construction. The Chennai Bypass connecting NH45 to NH4 blocks the east flowing drainage causing flooding in Anna Nagar, Porur, Vanagaram, Maduravoyal, Mugappair and Ambattur. The Maduravoyal Lake has shrunk from 120 acres to 25 acres. Ditto with Ambattur, Kodungaiyur and Adambakkam tanks. The Koyambedu drain and the surplus channels from Korattur and Ambattur tanks are missing. Sections of the Veerangal Odai connecting Adambakkam tank to Pallikaranai are missing. The South Buckingham Canal from Adyar creek to Kovalam creek has been squeezed from its original width of 25 metres to 10 metres in many places due to the Mass Rapid Transit System railway stations. Important flood retention structures such as Virugambakkam, Padi and Villivakkam tanks are officially abandoned.”
The first lesson for Panaji is to restore full natural flow in Nagali-Taleigao rivulet up to Tonca and clear manmade barricades and natural shoals that have blocked tidal circulation in the Santa Inez Creek behind Campal indoor stadium and opposite Inox complex.
The second lesson is to plan an integrated drainage system extending from Bainguinim hillock to source of Chimbel Creek, creeks of Chirculem, Calapur, Ourem and Rovalobandh, Durgavadi. Decongestion of the 30 silted arches of the Patto-Panaji to Patto-Ribander causeway should be an integral part of this plan.
The third lesson is urgent need for deconcretisation of open areas in front of buildings, parking lots and need to increase pervious area to increase natural percolation of rainwater. Panaji is getting heavily covered with asphalt, concrete and pavement tiles and an ideal ratio is 0.5 is needed (fifty per cent open area in the city should be pervious or porous permitting easy absorption of rainwater in subsoil).
Fourth lesson is to build large box type culverts or RCC cross drains from Old Miramar Caranzalem road to the Miramar beach to permit smooth drainage of stagnant water from Campal, Miramar and Caranzalem area. The Old RCC pipes below the roads have sunk deep in the sand and have become useless. One can see artificial lakes in Caranzalem due to water stagnation. The private community centre at Fontainhas, which has come up on a plot reclaimed from old drainage channel of Ourem creek that kept Fontainhas dry for centuries needs to be demolished after a detailed judicial investigation to restore the original drainage of the ward into Ourem creek.
The Campal Lake is the drainage lifeline of a densely settled area. Its connectivity to fire brigade arm of Santa Inez creek needs to be restored. The Mala Lake doesn’t have any tidal inlet or outlet so it will overflow during rains and flood nearby houses. This outlet has been deliberately blocked below the road and near the petrol pump. Goa archives needs to be immediately shifted to a higher, drier and safer location as it will get damaged in case of floods. If it rains with high intensity for a week then just like Chennai, Panaji will not survive flooding.