Climate change & urban flood

 

Chandan Sharma

 The recent cases of urban flood has certainly created a big question mark of urban planning and environmental issues as it has not spared any major city and caused loss of life and huge damage of property. In 2019 over 400 people have been died due to flood.

 Mumbai has been a victim of urban flood for years. 26^th and 27^th July 2005 have been classified as the days of heavy to very heavy rains as the city received more than 200 mm/day rainfall. Mumbai’s Santa Cruz airport recorded 944 mm of rainfall on 27^th July.

 Almost all years the metropolitan city faced similar kind of situation. Needless to say that greed of land, unplanned and unauthorised developments have been among major factors of urban flooding in the city.

 Not only Mumbai but Chennai, Delhi, Kolkata, Noida, Srinagar and even several cities of Bihar, Maharashtra, Rajsthan, Gujrat and Kerala too have been affected by the phenomena of urban flooding. Even the rescue team of army, NDRF & SDRF too have been deployed in those areas where rainfalls used to be a rare event.

 The case of Delhi is not very much different as far as urban planning and unauthorised cluster development is concerned. The habit of mindless throwing of plastic garbage is another major reason for choking of sewer lines. As a local councillor, responsible for looking after the affairs of sewer lines of municipal corporation in his area, admits that some people sometimes used to choke sewer lines with the help of these plastic garbage without knowing its wider impact in the area. 

 But Delhi has another problem too. It receives water from other states too, that causes flood in city sometimes. In the last two days the city is facing flood like situation in some areas due to massive release of water from Haryana. Although, it is bound to recede in next few days but the damages will certainly affect the city despite all alertness.

There are several reasons of urban flood. According to a research:

·        Urban flooding is caused by heavy rainfall overwhelming drainage capacity.

·        These are very likely to increase if no changes are made to management of urban drainage.

·        Economic and social impact are high although the number of casualties may be limited

·        If an intense rainfall burst occus, causing a large amount of rain within a brief period, flash flooding may occur with little or no warning.

·        Floodplains, often under the control of built infrastructure have been exploited throughout the world for food production, human sattlements and these are vulnerable to flood damage.

 A lot of the sewerage and drainage network is old and its condition is unknown. They cannot cope with the volume of water or are blocked by rubbish and by no-biodegradeble plastic bags. Sewers overflow because of illegal connections and sewer system can not cope with the increased volume of water.

 Development encroach floodplains, obstructing floodways and causing loss of natural flood storage. Mindless urbanisation has resulted  loss of floodplains and endengering ecology, reduced infiltration and reduced groundwater recharge.

 On the other hand, climate change is certainly a big reason for urban flood and flash flood.

 “States like Gujrat, Rajsthan, drought affected regions of Maharashra are now facing flash flood or urban flood like situation. These are the areas, where water is really a rare commodity. This certainly reflects the impact of climate change in the area”, admits a veteran environmentalist in Delhi.

“Climate behaviour is certainly unpredictable these days and it has a role in urban flooding too”, he says.

(Yuvavani.com is re-producing the article for readers as monsoon arrived in several parts of the country) (A pvt. initiative)