CHENNAI: North Chennai could soon have an integrated stormwater drain network in Kosasthalaiyar Basin with the Asian Development Bank funding the city corporation in strengthening the urban flood protection infrastructure in the entire 128 square kilometres of the basin falling within the corporation limits.
It is learnt that the state has sought a loan of USD 251 million from ADB's regular ordinary capital resources to help finance the project. The project is estimated to cost USD 358.5 million. Official sources said tenders have already been floated for construction of an integrated storm water drain in Retteri Lake Watershed in Kosasthalaiyar basin in the extended areas of the Greater Chennai Corporation.
The move would bring much needed relief to residents as work on the integrated stormwater drain network in Kosasthalaiyar basin has not begun despite an announcement made in the Assembly in 2014. The city has four drainage basins - Cooum, Adyar, Kosasthalaiyar and Kovalam - which are divided into 16 watersheds with 1,894 km of stormwater drains.
The city corporation has been building an integrated flood management system while aiming to expand the stormwater drainage system throughout its jurisdiction. The World Bank is supporting the city corporation to improve drainage in the Adyar and Cooum river basins in the central zone and KfW, a German state-owned development bank, is helping improve drainage in Kovalam river basin in the south.
With support of other development partners, the stormwater drainage in all other basins within the city corporation have already been improved, or plans are at advanced stages of preparation. The project is considered a general intervention as it will benefit 14.4 percent of poor and 85.6 percent of non-poor households in the project area, states the ADB project document.
The project will provide substantial improvement in the living standards of residents of the project area, especially the poor and other vulnerable people, through improvements in urban flood protection infrastructure such as roadside drainage, channels and restored waterbodies. The poor will be better protected against flood risks as a result of the proposed project, says the ADB project document.
According to the ADB, the state government has requested support for the proposed Integrated Urban Flood Management for the Chennai-Kosasthalaiyar Basin Project to support the Chennai corporation to increase its resilience to extreme weather events by strengthening urban flood protection infrastructure while recharging groundwater.
The proposed project aims to address many of the root causes of floods in Chennai through construction of flood management assets in the Kosasthalaiyar basin and by strengthening the capacity of the city corporation. Gaps in the city corporation's capacity shall be identified and strengthened through the project to ensure sustainability of the investments.
These include upgrading climate-resilient, urban flood protection infrastructure through laying 588 km of new stormwater drains adopting a 2-year return period to handle heavy rainfall.
The other works include improvement of 11.25 km primary stormwater channels, rehabilitation of community rainwater harvesting structures to improve groundwater recharge and reduce coastal salinity intrusion and construction of two energy-efficient water pumping stations.