Urban Flooding –IAS CSE Mains Answer Writing Constructing Great Answer for 2020 Exam: Do's and Don'ts

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Questions with Sample Answer for 2020 Exam

  • What is urban flooding?

  • Is it rising Globally?

  • What can planners look into?

  • Is Urban Flooding more severe than rural flooding and differences?

  • What are NDMA guidelines in Urban Flooding?

  • What are the factors affecting urban flooding?

What to leave

What to Leave

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Man-Made Disaster

Severe if combined with upper air circulation

Flash floods

Flood events are becoming more frequent.

Larger growth in medium and small floods.

Characteristics of Urban Flooding

  • Increase in flood peaks by 2-8 times

  • Increase in flood volumes by up to 6 times

  • Decrease in time required to reach flood peak

  • Excessive economic losses (in the form of damage to property and loss of productivity)


❌ Extreme weather

❌ Lack of administrative framework

❌Lack of Lakes

👌 Vanishing water bodies

❌ Heavy Rainfall

👌 Expanding impervious land cover / Paving decreases absorption

How infiltration works

How Infiltration Works

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👌 Silting – drains carry sediments (Blocked drainage)

👌 Unplanned urbanization

👌 Encroachment in natural drainage system

👌 Deforestation

👌 Population pressure

👌 Illegal colonies

👌 Poor management

👌 Lack of flood control measures

👌 Removal of native vegetation leads to higher runoff & velocity


  • Damage to property

  • Damage to life

  • Loss of employment for daily earners

  • Loss of revenue

  • Damage to surrounding

  • Harm to livestock

  • Diseases – mainly water borne

  • Contaminated drinking water

  • Psychological impacts

  • Public inconvenience

  • Traffic flooding

  • Collapse of bridges

Remedies and Solutions

What to include

What to Include

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Remedies for water issues

Remedies for Water Issues

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  • Make livable, resilient and sustainable

  • Use of porous construction material for pavements

  • Protecting lakes/water bodies from encroachments

  • Stop illegal construction

  • Use vacant space

  • Urban gardening (Milwaukee, Wisconsin)

  • Green roof program (Chicago, Illinois)

  • Reforestation

  • Revitalize natural drainage systems

  • Groundwater recharge

  • Flood management

  • Improve drainage systems

  • Reinforce weak building

  • Identify vulnerable areas

  • Create awareness

  • Better monsoon forecasting by IMD – Pratyush and Mihir

  • Artificial recharge trenches

  • Efforts by Bhuvan & National Urban Information System (NUIS)

  • Construction of gates to prevent backflow as in Mumbai tidal waters

  • NDRF, under Ministry of Home Affairs formed under Disaster Management Act, 2005 – personnel of CRPF, BSF

  • Set up emergency response shelters

  • Coordinate rescue plans

  • Epidemic Control Unit

  • Work around power supply

  • Crowd management

  • Integrate development and urban governance

  • Disaster Management – NDMA guidelines

  • Sustainable Urban Drainage Systems (SUDS) – Amount of water, quality of water and biodiversity



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International Efforts

  • Metro on Portland, USA

  • Under bridge and over bridge have inlets to capture excess water, which is collected and watered to the plants alongside

Recent Examples


  • Nashville in 2010

  • Chicago in 2013

  • Detroit in 2014

  • Texas in 2015


what is missing

What is Missing

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  • Hyderabad in 2000

  • Ahmedabad in 2001

  • Delhi in 2002 and 2003

  • Chennai in 2004

  • Mumbai in 2005

  • Surat in 2006

  • Kolkata in 2007

  • Jamshedpur in 2008

  • Delhi in 2009

  • Guwahati and Delhi in 2010

  • Srinagar in 2014 - inundated as river Jhelum crossed danger mark. Water was as high as 12 feet in many neighborhoods

  • Chennai Floods 2015 (374 mm in 24 hours) surpassed 1901 record

  • Bengaluru Floods (128.7 mm in single day) – record in 127 years

  • Uttarakhand floods - opening of flood gates during heavy rainfall.

  • Assam floods - high investments made on embankments along Brahmaputra.

NDMA explained that catchment area increases the flood peaks from 1.8 to 8 times and flood volumes by up to 6 times

Standard Operating Procedures (SOP) includes three phases of disaster management for effective and efficient response to urban flooding:

Pre-Monsoon Phase:

  • Preparedness: Planning for Disaster Reduction

During Monsoon Phase:

  • Early Warning

  • Effective Response and Management

  • Relief planning and execution

Post-Monsoon Phase:

  • Restoration and Re-habilitation

Role of NDMA & Recommendations

  • Create a National Hydro-meteorological Network- provide early warning

  • Use of Doppler Weather Radars

  • Contour mapping

  • Pre-monsoon desilting

  • Rainwater harvesting in every building

  • Concept of rain gardens

  • Expand database of the National Urban Information System (NUIS)

  • Delink urban flooding from riverine flooding

  • Flood shelters

  • Post-flood management – restoration of power and telecommunication

  • Awareness by media and corporate sector