GUWAHATI, July 23 - The report prepared by the CGSD, Earth Institute of Columbia University, New York, in association with the Sustainable Urbanism International, Bangalore, and the Indian Institute of Technology, New Delhi, on Guwahati’s flash flood problem, has laid more emphasis on preventive actions to reduce the risk of disaster rather than the actions during flood emergencies or post-flood relief activities. The report was prepared by the Columbia University team on behalf of the Assam State Disaster Management Authority (ASDMA) in 2015.
It has also called for steps to develop a ‘One Drain Plan of Action’ for Guwahati for government funding.
It has focused on some key areas of intervention. These include urban planning and development, natural resources (hills and water bodies), data, information and decisions, natural and artificial drainage, community and institutions.
It said risk factors behind urban flooding in Guwahati are integrally connected to increasing risk of extreme rainfall due to climate change. Hence, both short-term and long-term interventions need to be undertaken to reduce the risk of disaster for Guwahati from flooding and mitigate its impacts. It has laid emphasis on practical recommendations towards preventive actions to reduce the risk of disasters from urban flooding.
It said given the increasing flooding events/increasing proscribed zones in terms of landslide, flood and erosion-prone areas should be clearly demarcated to help control urban development and to further minimise the risk by developing and enforcing bylaws.
Hill and forest areas that have been designated as eco-sensitive zones under the city’s Comprehensive Master Plan (CMP) should not be developed.
Maps of Guwahati that clearly show flood and erosion-prone areas, and soils unsuitable for percolation and zones that are proscribed for existing buildings by using available sophisticated high resolution remote-sensed information and technically sophisticated staff and faculty of NRSA, IIT and Assam Engineering College, amongst others, should also be made available, said the report.
It also laid stress on zoning of the hazard-prone areas and delineation of the area after careful examination of the historical flood data and consultation with the local community. Engaging community in this exercise is critical since zoning regulations will affect them in multiple ways, it added.
Critical social assets such as school, hospitals, fire stations, and open spaces should be included in the zone. Provisions should be made for vulnerable population such as elderly, children and economically weaker classes.
It further stated that a plan for enhanced number of affordable housing for lower income families (to take pressure off the hills and forests surrounding Guwahati) should also be prepared.
Moreover, a plan for three new towns and for enhancing density of the existing residential areas in the new master plan should also be implemented. It also underlined the need to re-examine the CMP to enhance land allocation for residential use.
It stated that road levels should be assessed, rationalised and modified to allow water to flow naturally. Road levels should be matched to other road/drain levels and to the levels of the houses in the areas (since many road levels are higher than the house levels).
The roads that are frequently flooded should be identified and alternative routes should also be identified. An underground sewage system is urgently necessary for the city. The absence of sewage segregation is a major health hazard during floods, it said. No sewage connections should be permitted with outfall onto open storm water drains, added the report.
It further said the main electric transformers in the flood-prone areas should be relocated to higher ground. Solar power generators should be installed as backups in these areas.
A series of public consultation on “why are we destroying Guwahati’s wetlands and water bodies” should be held and detailed maps of Deepor Beel, Silsako Beel, Bondajaan Beel, Borsola Beel and Sarusala Beel (that are protected by the Guwahati Water Bodies Act of 2008/10) should be prepared.
Sustainable drainage systems (SuDS) should be developed for the city to provide an alternative to the direct channelling of surface water through networks of pipes and sewers to nearby watercourses, which will be effective in reducing pressure on the existing drains following heavy rainfall, it said.
It observed that the city lacks a formal local warning system for urban flooding. NESAC’s Flood Early Warning System for riverine flooding is extremely useful for upstream information.
It has recommended establishment of an urban flood management cell/nodal committee within the ASDMA that has representatives from key departments and agencies as well as expert advisors, to be chaired by the Chief Secretary. This cell/nodal committee will be empowered to direct all activities pertaining to flood management and landslides.