Social Sciences, asked by vanithanaren30, 1 day ago

Disscusion on recent floods

Answers

Answered by anushkasinha98
0

Meteorological Factors: Heavy rainfall, cyclonic storms, and thunderstorms. Hydrological Factors: Overbank flow channel networks, the occurrence of high tides impeding the drainage in coastal cities. Anthropogenic Factors: Unplanned Urbanization: Unplanned Urbanization is the key cause of urban flooding.

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Answered by mk1330066
0

Answer:

Floods in the Indian subcontinent have affected habitat,

population, economy, etc. Due to the detrimental

effects of recent floods on the economy, governance,

etc., it is imperative to understand the associated

dynamics, manifestations and fallouts for proper policy

planning recommendations. The present study endea-

vours to provide an integrated rationale of meteoro-

logical and geomorphological aspects associated with

four recent extreme floods in Uttarakhand (2013),

Srinagar (2014), Chennai (2015) and Gujarat (2017).

It is important to mention here that these floods

occurred under different atmospheric circulations and

geomorphological setting, and had an entirely different

gambit for policy planning and governance. Consoli-

dation of these issues will help policy planners and

technologists, in case advance warning system based

on these findings can be developed.

Keywords: Advance warning system, disaster mana-

gement, floods, governance, policy planning.

RAINFALL extremes cause flooding1

. Increased surface

run-off, and precipitation higher than the capacity of

outgoing discharge cause the water level to rise, leading

to submergence of regions, debris flows/landslides,

water-borne health disasters, etc.2

and posing threats to

sustainable development3

. Floods impact the ecosystem

and society by destroying habitats, affecting lives,

damaging infrastructure, etc. Nearly 40 m ha area in India

is flood-prone and every year nearly 8 m ha of land is

affected by floods. Apart from these, floods during rabi

and kharif seasons affect food security of the nation. Due

to warming climate, increased frequency of rainfall

extremes is reported in India4

. In addition, in recent dec-

ades, warming trend over the Indian Ocean5

has potentially

enhanced moisture supply leading to rainfall extremes in

the country6

. Abrupt variability and increased uncertain-

ties of rainfall patterns, periods, days, amount and risk of

weather extremes – as an impact of global climate

change – aggravated by ecological and anthropogenic

factors, pose ever-increasing risk of flood disaster7

.

However, increased atmospheric water vapour, though

favourable for intense rainfall events, by itself is not suf-

ficient to produce rainfall. Favourable thermodynamic/

dynamic conditions and rising motion in the atmosphere

are necessary for rainfall8

.

Geomorphological settings along with rainfall

extremes have led to flooding. In-flow and out-flow

limits of sewerage also contribute to flooding. Inundation

of a geomorphic substrate by flooding follows a definite

pattern. Any infringement to the natural flow path of a

river has a disastrous effect on the habitants.

In this article, we briefly discuss the unique geomor-

phic set-up of three major recent flood-affected regions of

India: (i) June 2013 Uttarakhand flood in Upper Ganga

valley, (ii) September 2014 Kashmir flood in Jhelum

river and (iii) December 2015 Chennai flood. Geomor-

phic limitations of the terrain in different geological

settings causing similar disaster in response to analogous

weather phenomenon are highlighted. In addition, Gujarat

(2017) flood is discussed in brief, which occurred only

with atmospheric forcings. Mechanisms and forcings

behind the occurrence of these floods are analysed. This

combined analysis may help the policy planners to sug-

gest proper recommendations.

Floods in association with Indian summer

monsoon

The onset of the Indian Summer Monsoon (ISM) and its

advance bring rain over different parts of India. ISM has

inter-annual and intra-seasonal phases as onset and

advance (mid-May to mid-July), peak rainfall (July to

August) and withdrawal (mid-September to mid-October).

In addition, latent heat source shifts over northern India

due to shifting of Intertropical Convergence Zone (ITCZ),

which generally stays between 20° and 30°N during the

peak monsoon (July–August). The onset and advance

phase is often accompanied by one or more transient

disturbances. Their movements not only advance the

monsoon isochrones to different parts of India, but are

accompanied by heavy rainfall in the vicinity of monsoon

transients during this phase. Heavy to very heavy

monsoon rainfall is normally associated with vigorous

monsoon conditions, low pressure systems and monsoon

breaks9

. In the region of the Himalaya, occasionally low

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