THEORETICAL FRAMEWORK
Introduction
Causes
In physical terms, a flood is a high stage in a watercourse, such as a river, drain, or tributary, or
a water holding body, such as a lake, pond, reservoir, seas, ocean, or other low-lying places, at
which water overflows its banks and inundates the surrounding areas.
Natural disasters such as riverine floods are the most common and widespread. No country is
completely devoid of flood danger, while flood prone areas are often restricted to specific
rivers and floodplains, as well as specific estuaries and delta zones.
Sea flooding is linked to estuaries and delta areas, which are more vulnerable if they are also in
cyclone-prone locations with sea surges, and/or when the coastal lowlands are subsiding due to
sediment loading and/or man-made deep-well water extraction.
Flash floods are more localized in impact than riverine, rain or sea floods. They are
experienced in both humid and semi-dry regions where landscape combinations of steep slopes
and sparse vegetation lead to intense short-duration rainfall.
Urban floods are caused by natural events and anthropogenic activities. In Indian cities
flooding is becoming frequent due to both human factors and meteorological/hydrological
factors, with the former factor being more predominant. some of the issues contributing to
urban floods are listed below:
1. Planning issues: Increasing population, habitations coming up in low-lying areas,
encroachment on drainage channels and immediate upper catchment of hilly urban areas.
2. Technical issues: Increased imperviousness leading to increased runoff as compared to
drainage capacity, improper waste disposal resulting in clogged drains, high intensity –
high load of runoff.
3. Meteorological issues: Exacerbated by changing climate, resulting in extreme events,
NASA studies indicate that the urban heat island effect also results in increased rainfall
over urban areas.
4. Policy issues: Lack of integrated flood control implementing agency
Impacts - flooding in urban areas affects more than one sector
1.
2.
3.
4.
5.
Riverine floods
Sea flooding
Flash floods
6.
7.
Urban Floods
Urban floods are a result of inadequate or poor
maintenance of storm water drains, improper planning,
encroachment on drains and water bodies, occupation of
low-lying areas, modification of catchments, and climate
change. Urban flooding is typically characterized by:
1. Increase in flood peaks by 2-8 times;
Traffic jams
Damage to public and private property
Mixing of solid waste in flood waters causing further choking of drains
Vector and water borne disease
In coastal cities, increased inundation of low-lying areas during high tide, reduced
capacity of drains to discharge storm water
Disruption of power supply and telecommunication
Mixing of faecal matter in the flood water due to open defecation
Solutions
Mumbai floods
2. Increase in flood volumes by up to 6 times;
3. Decrease in time required to reach flood peak;
4. Excessive economic losses (in the form of damage to
property and loss of productivity)
Bangaluru floods
URBAN FLOODING AND MITIGATION MEASURES IN GURUGRAM CITY
An integrated approach combining watershed and land use management with development
planning, engineering measures, flood preparedness, and emergency management should be
adopted for controlling urban floods. Three aspects viz. flood avoidance, flood tolerance and
flood resilience should be addressed in an integrated way for flood management in cities.
Technical measures include:
a. Planned and proper construction of drainage network
b. Regular maintenance of storm water drains
c. Use of porous construction material for pavements
d. Putting in place water sensitive infrastructure
e. Taking drainage basin as the base for city master plans.
f. Protecting lakes/water bodies from encroachments and clearing existing encroachments
by the departments/ agencies concerned.
g. Rejuvenating water bodies back to their original state
GURU RAM DASS SCHOOL OF PLANNING
GURU NANAK DEV UNIVERSITY,AMRITSAR
M. Plan. (URBAN) 4th SEM
Year 2020-22
GID – 681: THESIS
Rajat Bariwal
Sheet No:- 1
THEORETICAL FRAMEWORK
Urban Flooding Scenario
Urban Flood Disaster Risk Management
In Asia, urban flooding is a frequent phenomenon. Almost every city is vulnerable to urban
flooding in one way or another, and urban dwellers are at high risk. In urban environments,
farmland, vegetation cover, and bare soil have been converted into built-up areas. As a result,
water runs-off of the concrete structures, sometime known as pluvial flooding or urban
flooding. In urban areas, with rapid increase in impermeable surfaces and urban development,
the likelihood of flooding has increased. Similarly, the intensity of urban floods becomes
higher with prolonged rainfall.
The Yokohama Strategy for a Safer World: Guidelines for Natural Disaster Prevention,
Preparedness and Mitigation and its Plan of Action adopted in 1994 provides landmark guidance
on reducing disaster risk and the impacts of disasters.
Urban Flood Risk In India
There has been an increasing trend of urban flood disasters in India over the past several
years whereby major cities in India have been severely affected. The most notable amongst
them are 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
and Guwahati and Delhi in 2010.
NDMA Guidelines
Mumbai floods of July 2005 turned out to be an eye-opener. Realizing that the causes of
urban flooding are different and so also are the strategies to deal with them, NDMA has for
the first time decided to address urban flooding as a separate disaster, delinking it from
floods. NDMA commenced its efforts to formulate the Flood Guidelines in 2006 and
released them in 2008.
Mitigation
The theory behind disaster mitigation is a simple one: by making an investment of time,
money and planning prior to the occurrence of natural disasters, there can be tremendous
savings that result from reducing the impact of natural disasters when they inevitably occur.
Brenner (1993)
URBAN FLOODING AND MITIGATION MEASURES IN GURUGRAM CITY
GURU RAM DASS SCHOOL OF PLANNING
GURU NANAK DEV UNIVERSITY,AMRITSAR
M. Plan. (URBAN) 4th SEM
Year 2020-22
GID – 681: THESIS
Rajat Bariwal
Sheet No:- 1
THEORETICAL FRAMEWORK
Urban Flood Disaster Risk Management
The Yokohama Strategy for a Safer World: Guidelines for Natural Disaster Prevention, Preparedness and Mitigation and its Plan of Action adopted in 1994 provides landmark guidance on reducing
disaster risk and the impacts of disasters.
The review of progress made in implementing the Yokohama Strategy identifies major challenges for the coming years in ensuring more systematic action to address disaster risks in the context of
sustainable development and in building resilience through enhanced national and local capabilities to manage and reduce risk.
Urban Flood Disaster Risk
Management
Identification of Issues in Urban
Flood Disaster Risk Management
Watershed as Basis for Management
of Urban Flooding
Risk, Hazard Assessment and
Mapping
Following are some of the
shortcomings in management of
Urban Flooding:
i) Comprehensive risk assessment,
ii) Factoring risks in development
planning,
iii) Coordination among different
institutions,
iv) Lack of information sharing,
v) Disintegrated investment decisions,
vi) Lack of consultation with
stakeholders.
Following actions for Urban Flooding
Management will be taken on
Watershed Basis:
i. Preparedness and mitigation,
ii. Early warning and communication,
iii. Response,
iv. Awareness generation, and
v. Community capacity development
Risk assessment that provides the
planner with an estimate of the
expected material losses includes:
i) Identification of areas at risk upon
its exposure to hazard,
ii) Classification of structures
according to function,
iv) Estimation of risk for each
structure type, and
v) Estimation of all risks for each
function and then for each area.
Vulnerability
Assessment
Analysis
and
Risk
Estimation of Possible Inundation
levels
Estimation of Flood Damages
Ward level Risk Reduction and
Vulnerability Assessment
Reducing Vulnerability
Estimation of Flood Damages
‐ Reducing Physical Vulnerability of
People and Infrastructure
‐ Reducing
Socio‐economic
Vulnerability
‐ Insurance and Risk Transfer
URBAN FLOODING AND MITIGATION MEASURES IN GURUGRAM CITY
GURU RAM DASS SCHOOL OF PLANNING
GURU NANAK DEV UNIVERSITY,AMRITSAR
M. Plan. (URBAN) 4th SEM
Year 2020-22
GID – 681: THESIS
Rajat Bariwal
Sheet No:- 1