Shrinking Water bodies and Urban Floods
Urban water bodies have been a victim of unplanned urbanisation in India. Many of the urban water bodies have been encroached in major urban centres of the country. Shrinking of water bodies is interconnected to the urban floods.
• Lakes and wetlands are an important part of urban ecosystem. Unplanned and unregulated rapid urbanization has increased the pressure on adjacent water bodies.
• Burgeoning human population coupled with the increased urban concentration has escalated both the frequency and severity of disasters like urban floods. Eventually, shrink in water bodies cause risk of urban floods.
• The number of water bodies is on the verge of declining For instance- Bangalore had 262 lakes in the 1960s; now only 10 of them hold water. At least 137 lakes were listed in Ahmedabad in 2001; construction work started on 65 of them.
• Urbanization is the principal cause that have cascaded impact on other reasons as well, such as river flood encroachment, disposal of sewage, groundwater decline leading to fall in the level of water, unplanned tourism and absence of administrative framework.
Major Reasons and Interconnections with floods
o Pollution: There has been an exponential increase in the urban population without corresponding expansion of civic facilities such as infrastructure for the disposal of waste.As more people are migrating to cities, the urban civic services are becoming less adequate. As a result, most urban water bodies in India are suffering because of pollution.Sometimes excessive solid waste in water blocks the drain andaffects the channels during rainy seasons which subsequently causes flood.
For instance-the water bodies have been turned into landfills in several cases. Guwahati’s Deeporbeel, for example, is used by the municipal corporation to dump solid waste since 2006. Even the Pallikarni marshland in Chennai is used for solid waste dumping.
o Encroachment: This is another major threat to urban water bodies. As more people have been migrating to cities, availability of land has been getting scarce.Encroachment led to decrease in catchment areas and reduce overall capacity of water body to hold water. So, excess water possess residential areas and consequently urban flooding take place.Charkop Lake in Maharashtra, Ousteri Lake in Puducherry, Deeporbeel in Guwahati are well-known examples of water bodies that were encroached.
o Illegal mining activities: Illegal mining for building material such as sand and quartzite on the catchment and bed of the lake have extremely damaging impact on the water body.
For example, the Jaisamand Lake in Jodhpur, once the only source of drinking water for the city, has been suffering from illegal mining in the catchment area for the last 20 years despite a court order to stop mining in 1999.
o Waste disposal in water bodies and drainage restrict the hydro logical flow of water causes water logging and consequently, urban floods taken place.
o Concretisation further added to water-logging, Due to high population density lack of maintenance of drainage cause choking during monsoonal period. This resulted into excess water and causes flood.A water body have well connected drainage pattern, now a days in most urban areas pressure is on both drainage branches as well as on water body. This makes residential and unplanned region prone to be a victim of urban flood.
According to the Union Ministry of Urban Development (MoUD), 31 per cent of the country was urbanised in 2011. The ministry says almost 50 per cent of the country will be urbanised by 2050. Thus there is dire need to adopt the sustainable development oriented towards management of urban water bodies, and legally enforceable urban planning law.
Water bodies have become even more critical in current times when cities are facing the challenge of rapid, unplanned urbanization.
Natural streams and watercourses, formed over thousands of years due to the forces of flowing water in the respective watersheds, have been altered because of urbanisation. This cause irreversible damages to the local ecosystem and affect the water index of the region.
Flood Mitigation: It should be the early strategic stages in order to reduce and manage the flood risks, especially those associated with development. The drainage system should also be part of the strategic approach to flood management.
Wetland Survey: Detailed survey of the wetlands should be done toMinimise the risk of flooding.
Comprehensive urban planning with proper study of topography, drainage, rainfall, soil lithology with improved flood water disposal system. Also vibrant flood forecasting system should be inducted.