How is Chennai preparing to tackle the rains?


The floods of December 2015 have made the various departments of the Government think beyond conventional solutions for Disaster Management.

As part of a long term plan, the Tamil Nadu Urban Infrastructure and Financial Services Ltd (TNUIFSL) is currently floating a tender for an Early Warning System, that would typically predict the areas and levels of inundation depending on the rain forecast. This will take into account the level of moisture in the soil, which will increase the accuracy of the prediction. This is expected to take about 2-3 years.

LiDAR mapping, a remote sensing method that uses light in the form of a pulsed laser to measure variable distances, will be done as a part of this study. This can generate precise, three-dimensional visualisation of flood-prone areas across the Greater Chennai Area, with an accuracy of within 20 cm. Due to the nature of the study, the area will include all the catchment basins of Chennai, including Kosasthalayar, Cooum and Adyar, and all the minor drainage channels.

Large-scale and detailed bathymetry surveys (survey of underwater topography) are also to be carried out for higher accuracy. As part of the study, the number of rain gauge stations is also going to be increased, thereby increasing the accuracy in weather predictions.

The Tamil Nadu e-Governance Agency (TNeGA) is working with IBM and Greater Chennai Corporation to do flood inundation mapping for Chennai City. This would help Greater Chennai Corporation to plan rescue efforts in advance, based on the amount of rainfall predicted.

Infrastructure departments like the Department of Highways and PWD are working to improve the public assets under their control by doing large scale desilting and dredging operations. Most of the desilting has been done near the mouth of the major rivers in Chennai. It has been done in the banks and locations where river flow is low, as these are the areas where siltation is high. Some encroachments have been removed upstream to facilitate easier flow.

The Disaster Management and Mitigation Department that comes under the Revenue Department is setting up a Command Center to facilitate rescue and response.

CMDA has, in the past, done many studies that highlight the locations where serious interventions are required, and also the historic context and how the problem has evolved over the years. Some of these projects were initially managed via the JnNURM 1 & 2. Other states have tapped into schemes like AMRUT (Atal Mission for Rejuvenation and Urban Transformation) to jump-start work on similar areas.

Even the judiciary has done its part by putting a stay on registration of many unauthorised layouts, specifically the ones near water bodies.

There are other plans also to evaluate the level of deficiency in the drainage system across Greater Chennai.

(Watch this space for more urban updates)

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