Urban Floods in India
Context:
The death toll from floods in Assam has increased to 15, with over six lakh people affected. The number of affected people was 3.5 lakh in 11 districts on Friday.
Relevance:
GS-01 (Physical Geography)
Highlights:
- Severe flooding in Kerala and Assam is due to two cyclonic systems, one over Arunachal Pradesh and another off the coast of south Kerala. These systems have brought heavy rainfall to the northeastern States and Kerala.
- Swelling Rivers in Assam: Key rivers in Assam, such as Subansiri, Jiabharali, and Kopili, are swelling, affecting districts including Tinsukia, Darrang, and Nalbari.
- Severe Rainfall in Kerala: Kerala has experienced extremely heavy rainfall, with Udumbannoor recording 23 cm and Urumi seeing 14 cm. Other locations like Kottayam, Poonjar, and Vadavathur have also received significant rainfall.
- Preparedness and Monitoring: The Central Water Commission (CWC) has advised continuous monitoring and preparedness for potential flooding in Assam and Kerala, with real-time updates available on the CWC and IMD websites.
Urban Flooding:
- It is caused by heavy rainfall that overwhelms the capacity of drainage systems which leads to the inundation of land or property, particularly in more densely populated areas (like cities), .
- It is also caused mainly because of unplanned urbanisation (catchments).
- India is the third largest contributor to global settlements in flood-prone regions, after China and the U.S.
- It also ranks third in terms of new settlements expanding into flood-prone areas between 1985 and 2015, after China and Vietnam.
- This data shows susceptibility of the country to future flood-related challenges, necessitating careful considerations.
Causes:
- The large scale encroachments without widening the natural drains, leading to decrease in the capacity of the natural drains resulting in flooding.
- The current climate change that has caused an increase in the frequency of short duration heavy localised rainfall leading to higher water run-off.
- Unplanned and sudden release of water from dams and lakes lead to floods in an urban area, without giving the public enough time to respond.
- Example: The July 2023 flood in Delhi was magnified by 2 lakh cusecs of water discharged from the Hathnikund Barrage into the Yamuna river.
- Illegal mining of river sand and quartzite for the commercial use deplete the natural bed of the rivers and lakes which causes soil erosion and reduces the water retention capacity of the waterbody increasing the speed and scale of water flow.
- Example: Jaisamand Lake- Jodhpur, Cauvery river- Tamil Nadu
Way forward:
- Implementation of sustainable urban planning that includes more natural green spaces, retention ponds and permeable surfaces to absorb and manage water should be inculcated at prone areas.
- The government should invest in expanding the drainage infrastructure which also includes regular maintenance.
- Establish a Early warning system to alert the people, especially the residents so that they can evacuate to safer places.
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