Hyderabad urban flooding

Source- The Hindu

Syllabus- GS 3- Disaster and disaster management.

Context- Ineffective and unplanned hydra-geology of cities and town of India are more responsible for Hyderabad Urban Flooding than monsoon.

What is urban flooding?

• Urban flooding is the inundation of land or property in a built environment, particularly in more densely populated areas, caused by rainfall overwhelming the capacity of drainage systems, such as storm sewers.
• Urban flooding is significantly different from rural flooding- urbanization increases flood risk by up to 3 times, increased peak flow results in flooding very quickly. Further, it affects a large number of people due to the high population density in urban areas.

Mention the causes of recent floods in Hyderabad?

1. Unplanned development– Unplanned development, encroachments in riparian zones, failure of flood control structures, unplanned reservoir operations, poor drainage infrastructure, deforestation, land-use change and sedimentation in river beds are exacerbating floods.

• Urban flooding– Wetlands and watersheds play a vital role in absorbing excess rainfall, but regrettably, rapid urbanization in the twin cities has resulted in the loss of a large portion of the wetlands.
• Indiscriminate encroachment of waterways and wetlands, inadequate capacity of drains and lack of maintenance of the drainage infrastructure.
• An analysis by the Centre for Science and Environment in 2016 revealed that 3,245 hectares of water bodies were lost in Hyderabad between 1989 and 2001.

2. Neglect pre-disaster planning– The extent of the damage and the turmoil shows a lack of preparation and disaster mitigation, a problem that plagues most urban centres in the country.

• Overflowing of lakes– The Hussain Sagar Lake in the middle of the city and the breaching of stormwater drains.
• Waste management– Every water body has a holding capacity. But, with all the industrial waste and sewage being dumping into the lakes, the waste accumulated and has now affected the holding capacity of the lakes.
• All the nalas, storm drains, culverts are gone, either land-filled and build over or simply filled with garbage, detritus and forgotten.

What are the measures needed to mitigate this?

1. Hyderabad urgently needs to expand and remodel its drainage system.
2. Focusing on urban flood management– Risk mapping of the areas of the city should be done to assess the vulnerability, related to urban floods by using GIS technology.
3. Minimize the surface runoff- Limit, reduce or mitigate for impervious surface throughout the watershed by use of new engineering techniques like pervious pathways, parking lots should be considered and implements wherever possible to minimize the surface runoff.
4. Prioritizing Buffers, Flexibility and Adaptability – This includes reviewing safety criteria of dams and canals, re-building these with higher safety factors, creating new intermediate storages, and introducing dynamic reservoir management.

Way forward-

• The effects of flooding due to deluges can only be mitigated if urban planners take into account the hydro-geology of cities and ensure that construction, development and land occupation do not take place in a way that reduces the area of wetlands.