Urban Flooding – IAS CSE Mains Answer Writing Constructing Great Answer for 2022 Exam: Do՚s and Don՚ts

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Questions with Sample Answer for 2022 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

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)

Causes

  • Extreme weather
  • Lack of administrative framework
  • Lack of Lakes
  • Vanishing water bodies
  • Heavy Rainfall
  • Expanding impervious land cover/Paving decreases absorption
How Infiltration Works

👌 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

Effects

  • 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
Remedies for Water Issues

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

SAM and NSAM

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

USA

Nashville in 2010

Chicago in 2013

Detroit in 2014

Texas in 2015

India

What is Missing

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

Manishika