Hydrological Sciences Journal

ISSN: 0262-6667 (Print) 2150-3435 (Online) Journal homepage: http://www.tandfonline.com/loi/thsj20

Hydrological analysis of extreme rainfall events

and severe rainstorms over Uttarakhand, India

S. Nandargi, A. Gaur & S.S. Mulye

To cite this article: S. Nandargi, A. Gaur & S.S. Mulye (2015): Hydrological analysis of extreme
rainfall events and severe rainstorms over Uttarakhand, India, Hydrological Sciences Journal,
DOI: 10.1080/02626667.2015.1085990

To link to this article: http://dx.doi.org/10.1080/02626667.2015.1085990

Accepted author version posted online: 25

Aug 2015.

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Download by: [New York University] Date: 15 March 2016, At: 10:08
 Publisher: Taylor & Francis & IAHS

Journal: Hydrological Sciences Journal

DOI: 10.1080/02626667.2015.1085990
Hydrological analysis of extreme rainfall events and severe rainstorms over
Uttarakhand, India

S.Nandargi1, A.Gaur2 and S.S. Mulye3

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1 &3 Scientist, Indian Institute of Tropical Meteorology, Pune 411011, India

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2. M.Sc. Environmental Science Student, Bharathi Vidyapeeth, Pune 411043, India

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Abstract
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After the June 2013 disaster in the Uttarakhand Himalaya, lots of discussions are going on
how climate change is seeking revenge on mankind by endowing us with disasters! The event
was mostly linked with the occurrence of extreme event due to climate change. In view of
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this an attempt has been made in this paper to analyse the extreme rainfall events experienced
by the Uttarakhand during 1901 to 2013 using more than 100 station daily rainfall data. The
study revealed that during 113 years period, highest numbers of extreme events are recorded
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during 1961-1970 decade and to some extent in 1981-1990 decade. Thereafter there is
decrease in extreme rainfall events. The comparative study of extreme events prior to 1901
showed that 17-18 September 1880 rainstorm which occurred in the close vicinity of
Uttarakhand, caused serious floods and damage to lives and properties in the past. Extreme
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rainfall recorded by some stations during this unprecedented rainstorm has not been
surpassed till date.
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Key words extreme rainfall events; rainstorm; flood disasters; Uttarakhand, India
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1. Introduction
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Hydrological extreme events are typically defined as floods and droughts. Floods are
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associated with extreme rainfall (due to tropical storms, thunderstorms, orographic rainfall,
widespread extra tropical cyclones, etc.), while droughts are associated with a lack of
precipitation and often extremely high temperatures that contribute to drying. Floods are
often fairly local and develop on short time scales, while droughts are extensive and develop
over months or years. The loss of life and property from extreme hydrological events has
therefore caused society to focus on the causes and predictability of these events (Trenberth,
2011).
 2

Precipitation varies from year to year and over decades, and changes in its amount,
intensity, frequency, and type affecting the environment and the society. In other words,
rainfall and its variability are important factors of the global hydrological cycle affecting all
living organisms on the Earth. It is therefore, essential to study variability of rainfall on a
short time scale as it has a wide range of applications such as to compare model predictions
with atmospheric observations (Bell et al, 1993); to understand the atmospheric physics
(Kishtawal et al, 2001); to understand the local weather mechanisms (Hamada et al, 2008),
etc. In recent years, therefore, the study of rainfall characteristics has attracted everybody’s

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attention, especially because of extreme weather conditions and possible climatic changes
that have been observed.

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The most deadly flash flood of Oklahoma, Texas is the worst example of this year in
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the last week of May 2015. (http://www.weather.com). More than 170 locations at a time in
central and southern plains of Texas, Oklahoma, Louisiana, Arkansas, eastern Kansas and
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Missouri were in the girth of flood. The Blanco River, which rose 26 feet (7.8 m) in just one
hour due to catastrophic heavy rainfall of > 25 cm caused uprooting trees from the riverbank,
carrying entire houses downstream and destroying bridges and other infrastructure and left
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piles of debris of more than 6 m high.
.
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In recent past, heavy precipitation events have resulted in several damaging floods in
India. The consecutive flash floods over three major metro cities in the same year, i.e.,
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Mumbai in July 2005, Chennai in October and December 2005 and Bangalore in October
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2005 caused heavy damages to economy, loss of life, etc. (Guhatakurta et al, 2011). On 15–
18 June 2013, the Uttarakhand region experienced catastrophic heavy rainfall that washed
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away the area near the Kedarnath Temple killing hundreds of pilgrims and resulting in
damage to property. Similarly, due to torrential rain in September 2014, Jhelum and Chenab
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rivers in the Indian region experienced floods due to a severe increase in river level to more
than 7 m above the normal levels, resulting in the death of more than 300 people in J&K
(India) region and damage to property (www.revivekashmir.org).

Therefore, occurrence of exceptionally heavy rainfall events and associated flash

floods in recent past years inspired to study long-term changes in extreme rainfall over India.
Except some parts of central India, extreme rainfall flood risks are increasing significantly in
the country. In view of the above, in the present paper, on the basis of 100 years or more
 3

daily rainfall data, attempt has been made to study the extreme rainfall events over the
Uttarakhand region. The study will be useful for better hydrological planning, flood control
and disaster management over the region.

2. Review of the literature

Large numbers of studies have been carried out on heavy rainfall and associated flood at
national and international level. Rakhecha and Pisharoty (1996) on the basis of 80 years

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(1901-1980) rainfall data for 316 well distributed stations over the Indian region analysed the

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trends and persistence of extreme rainfall series using standard statistical tests. Their results
showed that the annual extreme rainfall records of most of the stations are free from trends

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and persistence. However, the extreme rainfall series at stations over the west coast, north of
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12oN and at some stations to the east of the Western Ghats over the central parts of the
peninsula showed a significant increasing trend at 95% level of confidence. Stations over the
southern peninsula and over the lower Ganga valley exhibit a decreasing trend at the same
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level of significance (Rakhecha and Soman, 1994).
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Using daily rainfall data of 1901 to 1990 period for 151 stations, Sinha Ray and
Srivastava (2000) analysed the trend in the occurrence of heavy rainfall events (7 cm) over
India. Their analysis showed a decreasing trend in heavy rainfall in all the seasons over most
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parts of the country. However, over northern west coast and a few stations in the northern
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parts (Haryana and Punjab), a significant increasing trend was found by the authors.
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Goswami et al (2006), using daily gridded rainfall data from India Meteorological
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Department (IMD) for 1951–2003 examined the trend of extreme rainfall over India.
However their study was confined to the central India only. Their study reported an increase
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in the frequency and the magnitude of extreme rain events and a significant decreasing trend
in the frequency of moderate events over central India.

Rajeevan et al (2008) used 104 years of gridded dataset and selected a box mostly
comprising central India similar to Goswami et al (2006) and examined the variability and
long-term trends of extreme rainfall events.
 4

It may be noted that for extreme rainfall analysis to study the behavior of changes in
the extreme events, real or actual station data is more realistic than the gridded dataset. In the
gridded datasets, extreme events will not be captured on most of the occasions due to
interpolation or averaging method used in gridding. This can even mislead the signals of
hydrological extremes for better disaster management.
Guhatakurta et al (2011) analysed the frequency of rainy days, rain days and heavy
rainfall days as well as one-day extreme rainfall and return period to observe the impact of
climate change on extreme rainfall events and flood risk in India using daily rainfall data for

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1901–2005 in more than 6000 rain gauge stations all over India. Their analysis revealed that
frequency of heavy rainfall events decreased significantly for most parts of the country.
Similarly frequency of extreme rainfall events has decreased in most of central and north

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India. The intensity of extreme rainfall has increased over coastal Andhra Pradesh and its

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adjoining areas, Saurashtra and Kutch, Orissa, West Bengal, parts of northeast India, and east
Rajasthan. Significant decrease in intensity as well as frequency of extreme rainfall has been
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observed over Chattisgarh, Jharkhand and some parts of north India.

Immediately after the June 2013 catastrophic flood event over Uttarakhand,
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Srinivasan (2013) discussed in his editorial note in Current Science journal, the possible
causes of the disaster, such as cloud burst, meteorological phenomena, glacial lake outburst
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flood, and landslide. He noted that such heavy rainfall events occurred in Uttarakhand in the
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past mostly in the months of July, August or September, whereas, for the first time, it
occurred in June 2013. Taking into consideration its devastating nature, the author
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emphasized the need for a better warning or forecasting system that can predict such disaster
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events at least a week earlier in the Himalayan region.

Kotal et al (2014) in their study analysed the dynamical and thermodynamical features
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derived from the IMD operational WRF model (27 km resolution) daily analysis fields
associated with the torrential rainfall episode during 16–18 June 2013 occurred over
Uttarakhand and its neighbouring states, causing flash floods, landslides, large-scale loss of
lives and damage to property. Their analysis suggests that due to strong interaction between
an oncoming mid-tropospheric trough in the westerlies and the strong lower-tropospheric
southeasterly monsoon wind flow in association with a monsoon low-pressure system over
the North Indian region, a lower tropospheric wind convergence zone developed over
Uttarakhand and its neighbouring regions. According to them this event was comparable with
 5

the Leh 2010 flash flood episode which indicated the relative positions of the Tibetan high,
monsoon low pressure system, westerly troughs and the position of the westerly jet stream
appear significant factors in the pumping of huge amounts of moisture into the Western
Himalayas.

On global scale also, while studying the impact of climate change, studies carried out
in recent past have shown that there is an increasing trend of extreme precipitation events in
USA and Australia (Easterling et al. 2000, Haylock and Nicholls 2000, Groisman et al. 2001;

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Kunkel 2003), western New Zealand (Salinger and Griffiths 2001), the UK in winter (Osborn
et al. 2000), and south Africa (Fauchereau et al. 2003). Extreme rainfall events in Canada
show no trend (Zhang et al. 2001; Kunkel 2003). Significantly decreasing trends in extreme

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rainfall events have been found in Western Australia (Haylock and Nicholls, 2000), south-

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east Asia and parts of central Pacific (Griffiths et al. 2003), northern and eastern New
Zealand (Salinger and Griffiths 2001), UK in summer (Osborn et al, 2000). Haylock et al.
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(2006) have recently addressed the trends in total and extreme rainfall over South America
and their links with sea surface temperatures.
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The survey made by Carpenter et al (2007) on a series of flash floods in the San
Bernardino Mountains showed that these chains of floods were in association with a record
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daily rainfall total over Los Angeles city. Although, floods ware mostly localized and of very
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short duration, caused significant damage to lives and property. Merz and Bloschl, (2008a,
2008b) in their study showed that the three way information viz. spatial, temporal and causal
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information can form an useful tool in diagnostic analyses of floods due to extreme rainfall
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events to assist in hydrologically based flood frequency estimation more precisely in small
basins than in larger catchments.. Trend analysis was carried out by Mishra and Singh (2010)
in order to know the changes in extreme precipitation over the Texas using rainfall data for
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the period 1925–2005 for 30 stations. Their results showed both increasing and decreasing
trend in different parts of Texas during pre- and post-climatic periods. In other study made by
Mishra et al (2011) for Texas river basin seasonal stream flow extremes during pre-industrial
and post-industrial periods showed no clear trend.

Considering the above, and knowing that upper reaches of the Ganga basin in
Uttarakhand region is always prone to extreme weather events, it is decided to analyse the 1-
day extreme rainfall events, their frequency and magnitude of rainfall amounts recorded over
 6

the Uttarakhand region during 1901 to 2013. Extreme Rainfall events recorded in the
monsoon months and their association with heavy rain spells has also been studied to know
the spatial distribution of these extreme rainfall events over the region.

3. Physiograhic and climatological features of the Uttarakhand State

Uttarakhand (formerly known as Uttaranchal) was formed on 9 November 2000 as the 27th

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State of India, when it was carved out of northern Uttar Pradesh. Located at the foothills of
the Himalayan mountain ranges, it is mostly a hilly State, having international boundaries
with Tibet in the north and Nepal in the east. To its northwest lies Himachal Pradesh, while to

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the south is Uttar Pradesh (see Fig. 1). Uttarakhand, being situated on the southern slope of

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mighty Himalayas, is rich in natural resources especially water and forests with many
glaciers, rivers, dense forests and snow-clad mountain peaks (see Fig. 1). Major peaks, viz.
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Nanda Devi, Kamet and Kedarnath; major rivers, viz. Ganga, Yamuna, Bhagirathi,
Alaknanda, Kosi and Mandakini, and major glaciers, viz. Gangotri, Nandadevi, Maiktoli and
Chorbani are the characteristic features of Uttarakhand.
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The total geographical area of Uttarakhand State is 51 125 km2 and, of this, 93% is
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mountainous, and 65% is covered by forest. Glaciers are located at the highest elevations and
have the coolest weather; the mountainous areas are covered by ice and bare rock. However
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there is dense tropical forest at the lower elevations. Two of India’s mightiest rivers, the
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Ganges and the Yamuna, have their origin in the glaciers of Uttarakhand. There are several
other perennial lakes and many streams in the region. Therefore, topography of Uttarakhand
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has a distinct range of landforms varying from hills and peaks to cliffs and crests thereby
dividing the state into two divisions, the western half as the Garhwal and the eastern half as
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the Kumaon region (see Fig. 2).

The climate of Uttarakhand is predominantly distinguished into two diverse divisions:

the major hilly terrain and the smaller lower plains. The northern part of the state is
enveloped by the mighty Himalayas, show complete traits of Himalayan climate exerting
profound influence on monsoon and rainfall patterns. The higher altitudes of the Uttarakhand
Himalayas (>4572 m) are cold throughout the year and at times become inaccessible due to
heavy snowfall. The eastern edges of the Himalayan ranges are subject to heavy rainfall
 7

while the western division is relatively dry. The summer season over the state extends from
April to June. Temperature during winter season ranges from below 0°C to about 15°C. The
winter season of the state generally extends from October to February. July to September is
the monsoon season over the Uttarakhand receiving about 90% of its annual rainfall during
this season.

4. Data used and Methodology

4.1 Data used

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Before the Indian Independence (i.e. 1947), the network of precipitation stations in the
Himalayas was very sparse. A few meteorological observatories were started by the British
Govt. during their colonial rule over the country, in the Himalayan sections of Kashmir,

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Punjab, Garhwal-Kumaon, north Bengal and Assam. After the Indian independence, a good

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number of meteorological stations were installed in different regions of the Himalayas under
various Hydro-electric and irrigation projects of the Central and State Governments and for
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forecasting floods in the rivers originating from the Himalayas.

Daily rainfall data for all the available stations (about 100) in and around the
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Uttarakhand region (see Fig. 2) were procured from:

a) National Climate Data Centre (NCDC), Indian Meteorological Department (IMD), Pune
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(1901-2013) and various publications of the IMD, viz. monthly, seasonal and annual
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reports, daily rainfall summary, weekly rainfall reports, etc.

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b) Rainfall records from the project authorities such as the National Thermal Power
Corporation (NTPC), the National Hydro-electric Power Corporation (NHPC), the
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Central Water Commission (CWC), New Delhi, working in the Himalayas for the
construction of irrigation systems and hydro-electric power projects in different river
basins.
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c) Daily rainfall data available as rainfall volumes from the Indian Institute of Tropical
Meteorology (IITM), Pune, for different states since 1871.
d) The rainfall registration authorities of Himachal Pradesh, Uttarakhand (formerly
Uttaranchal) and J&K states supplied daily rainfall data of the rain spells for the
Himalayan districts of their respective states.
e) The Forest Departments of the Himalayan states (1975-2000).
 8

Past extreme rainfall events (prior to 1901) were collected from the books, Climate of Uttar
Pradesh and Himachal Pradesh, published by the IMD. Stations having less than 10 years
data were not considered for the analysis.

4.2 Methodology
Data procured from IMD were first arranged in a uniform format and subjected to quality
check to remove any outliers. The outliers have been cross checked with the synoptic

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situations of that day mentioned in the IMD reports and corrections were carried out
wherever required. Excluding such outliers, a homogeneous series of 100 rainfall stations
have been prepared for the period 1901 to 2013 and the same has been used in the present

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analysis. For majority of these stations, extreme one-day rainfall data are available for more

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than 50 years. However, stations having less than 10-years data have not been considered in
this study.
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Frequency analysis of extreme one-day rainfall for each of the 100 stations was
carried out to know monthly, annual, seasonal and decadal variation over the state. To
calculate temporal and spatial distribution, these frequencies were divided into eight
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categories of rainfall magnitudes, as shown in Table 1. Frequencies of extreme rainfall events

(greater than 100 mm) recorded in each decade from 1901 to 2013 were also used and the
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causes of extreme rainfall events and floods due to them were studied. Comparison of
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extreme rainfall events in the period 1901–2013 was made with the past records prior to 1901
from different sources. The spatial distribution of extreme events and analysis of rainstorms
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associated with extreme rainfall in the period 1901–2013 was carried out using geographical
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information system (GIS) technology.

5. Meteorological situations causing extreme rainfall over Uttarakhand

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Magnitudes of highest or extreme rainfall are the basic tools in the estimation of probable
maximum precipitation (PMP) or extreme rainfall which is possible at a given point or a
region for a given duration. As stated earlier, being located close to the Himalayan ranges, the
Uttarakhand region receives heavy to very heavy rainfall during the southwest monsoon
season. The major meteorological situations responsible for causing heavy rainfall over the
region are:
 9

a) Monsoon depressions When low pressure areas from the Head Bay of Bengal travel
over the central parts of the country, some of them re-curve in a northerly to
northeasterly direction (Fig. 3), causing heavy to very heavy rainfall along the foot-
hills of the Himalayas (Dhar and Nandargi, 1993). In some years, depressions from
the Arabian Sea, after crossing the south Gujarat, north Maharashtra coasts, strike the
Garhwal-Kumaun region of the Himalayas causing heavy rains in the hills and valleys
of this region leading to severe floods, landslides and disruption of communications.
b) Break monsoon situations The monsoon, which is the predominant rainy season over

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the Indian sub-continent, undergoes 30 to 40 days intra-seasonal variations which are
known as active and break periods (Gadgil, 2003; Wang et al., 2005). When the axis
of the monsoon trough shifts to the foot-hills of the Himalayas from north Indian

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plains (known as setting in of ‘break situation’), very heavy rainfall occurs in the

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eastern and central Himalayas, causing serious flooding in the rivers of these regions
(Dhar et al, 1984). Break situations mostly occur during the monsoon months of July
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and August and occasionally in September.
c) Extra tropical disturbances Also called ‘Western Disturbances’ and originating from
the Mediterranean and Caspian seas in the far west, these move eastwards across Iran,
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Afghanistan, Pakistan, and extreme north India, causing rain and snow over the
Himalayas (Fig. 3), especially, in its western sector during the winter season
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(November–March) (Mani, 1981; Sikka 1999; Dhar and Nandargi 2005). The
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frequency of occurrence of these Western Disturbances is about four to five per

month during the monsoon season and six to seven per month during the winter
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months. By the time these disturbances reach the Central and the Eastern Himalayas,
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rain and snow contribution from them decreases substantially.

d) Accentuation of the western end of the seasonal monsoon trough over and near the
western sections of the Himalayas or the eastern end of the seasonal monsoon trough
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over and near the eastern sections of the Himalayas causes enhancement of the
rainfall over the respective sections of the Himalayas.

6. Frequency analysis of extreme rainfall events

Analysis of rainfall data revealed that one-day extreme rainfall (≥100 mm) events occurred in
all months of the year. The maximum frequency of extreme one-day rainfall was recorded in
the month of October (75) and lowest in November (2) (see Fig. 4). However, in different
seasons, the occurrence of extreme one-day rainfall was found to be more or less the same
 10

(Table 2). Forty stations recorded their annual highest one-day extreme rainfall in the range
of 200–300 mm (Table 1).

About 12 stations inside the Uttarakhand recorded more than 400 mm of rainfall in 1-
day (Table 3). Of these, Garbyang and Nainital stations recorded more than 500 mm of
highest 1-day rainfall. Except Garbyang (in January) and Bazpur (in October), rest of the
stations recorded their highest one-day rainfall in July, August and September monsoon
months. However, prior to 1901, Hardwar and Mussoorie stations have recorded 1-day

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extreme rainfall of 495.3 and 439.4 mm, respectively, in September 1880 and August 1890.
Sixteen stations near the Uttarakhand region recorded the highest one-day rainfall, of 400–
800 mm.

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The monthwise highest 1-day extreme rainfall recorded at different stations in and around the

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Uttarakhand region is summarized in Table 4. Most of the stations recorded one-day extreme
rainfall during May to October in the range of 100 to 300 mm, except Khadrala station
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(Mahasu District) which recorded one-day extreme rainfall of >700 mm in January. It is seen
from Table 4 that, at higher altitude, Khadrala station (Himachal Pradesh) just northwest of
Uttarakhand, has recorded the highest 1-day extreme rainfall in January, February and
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November, whereas in the plain areas, Dhampur station (Uttar Pradesh) located south of
Uttarakhand (Fig. 2), recorded the highest 1-day extreme rainfall in June, August and
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September. Simla (O) recorded the highest 1-day extreme rainfall of 800 mm in October.
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The altitudinal variation of extreme rainfall (Fig. 5) showed that stations (from right
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to left) lying to the leeside of the mountain ranges, in particular those located in the central
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part of the state, although at higher altitude, recorded less rainfall. However, stations lying to
the windward side, i.e. in the path of monsoon disturbances, both at high altitude and in the
plain, recorded heavy rainfall of higher magnitude.
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The magnitudes of extreme one-day rainfall in all the months and during different
seasons, years are given in Table 5. It is seen that magnitude of extreme one-day rainfall is
higher in the monsoon months for the stations inside as well as nearby the Uttarakhand state.
There is noteworthy decrease in the magnitude of extreme rainfall during March to May.

The spatial distribution of extreme one-day rainfall in and around the Uttarakhand
state (Fig. 6) shows that magnitude of highest one-day rainfall is < 300 mm in the most of the
 11

central parts of the Uttarakhand state. This is mostly due to the orographic influence over the
rainfall distribution as there are 86 high altitude peaks (> 6000 m) (see Figs 1 and 5) located
in this region. Stations falling to the windward side recorded heavy rainfall (> 300 mm) and
those which lie to the leeside recorded less rainfall (< 300 mm). Stations near the foot hills of
Himalayas recorded comparatively heavy rainfall ranging between 400 to more than 800 mm.
Broadly, stations in the central part of the state recorded less magnitude of extreme 1-day
rainfall than stations in the eastern or western part of the state.

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The decadal variation (see Fig. 7) showed that, prior to 1950, the number of one-day
extreme rainfall recorded was very few. This may be because there were fewer raingauge
stations in those days. After the independence of India in 1947, in collaboration with US

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Geological Survey, Dr. Dhar (Hon. Emeritus Scientist, IITM, Pune) and his team installed

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more raingauges in the entire Indian and Nepal Himalayas and, hence, there appears to be an
increase in extreme rainfall events after 1950 or so. In the 1951–2013 period, the most
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extreme events (34) were recorded in the 1961–1970 decade. Thereafter, there is a
noteworthy decrease in extreme rainfall events.
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The number of extreme rainfall events recorded on a yearly basis by individual

stations also supports the fact that there is a decrease in such events. Figure 8 shows some of
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the noteworthy stations showing a decreasing trend in extreme 1-day rainfall. More than 40%
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of the stations in Uttarakhand have shown a decreasing trend in extreme rainfall events and
very few (about 10–12) stations have shown an increasing trend.
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7. Extreme rainfall events and severe rainstorms

In addition to data on frequency of extreme rainfalls, it is usually necessary in the design of

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certain engineering structures, such as dams and bridges, to assume values of area covered by
the design storm and to determine a pattern of rainfall intensity before a hydrograph of runoff
can be constructed. An attempt has been made here to establish whether extreme rainfall
events are associated with rainstorms and thereby rainfall intensity.

As mentioned in Section 5, heavy to very heavy rainfall over the Uttarakhand region
occures due to cyclonic disturbances originating in the Bay of Bengal or the Arabian Sea and
movement of Western Disturbances in the extreme north of India during the monsoon season
 12

(see Fig. 3). The heavy rain spell or a rainstorm is defined as a spatial distribution of heavy
rainfall, yielding average depth of precipitation which equals or exceed a certain threshold
value over a region in association with some meteorological phenomena, such as low
pressure areas, depression or cyclonic storms (Abbi, 1972).

On scrutiny of long period daily rainfall data for stations in and around the
Uttarakhand region, it was seen that associated with extreme one-day rainfall, more than 40
heavy rain spells have occurred over the region in the period 1901–2013. Depending upon the

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area and topography of the study region and rainfall characteristics, a threshold value of
about 10% of the seasonal normal rainfall is considered for the selection of severe rainstorms.

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Estimation of maximum average rain depths from analysis of severe rainstorms over a

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region are normally made by the following methods, taking into consideration the orography,
nature and size of the basin/sub-basins or region, the amount of data availability and its
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suitability:
(i) depth–duration (DD) method,
(ii) depth–area–duration (DAD) method, or
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(iii) storm transposition technique.

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The main objective of all the above methods is to estimate the maximum possible rain
depths, which a basin or a region may experience in future years. The above methods are well
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documented in various publications like Hydrometeorology by Wiesner (1970), Manual of

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Hydrometeorology (IMD, 1972), WMO (1970, 1973 and 1986) manuals. In the present study
considering the high topography of the state, rainstorm analysis has been carried out by DD
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method. A brief description of the same is given in the following section.

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7.1 Depth–duration (DD) method

In this method, the catchment/ region is considered as a unit of study. All the heaviest rain
spells (severe rainstorms) experienced by a basin/region over a long period of time are
extracted and then analysed for different durations by the depth–duration (DD) method in
order to obtain average maximum basin rain depths. Maximum rain depths thus obtained are
plotted as DD curves and highest rain depths are determined from the envelope curves. The
envelope of all the rain depths, which is referred to as design rain depths or standard project
storms (SPS), is then determined for different durations. This method is normally used when
 13

daily rainfall data for a good network of stations are available for a sufficiently long period of
years. The method is most suitable for the estimation of design rain depths over catchments
located in mountainous regions or orographically influenced region and also near coastal
region.

Of the 40 heavy rain spells experienced in and around Uttarakhand in the period
1901–2013, there were 21 severe rainstorms over the state, of which one occurred in June,
five in July, four in August, nine in September and two in October. It was also noticed that

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these rain spells were of short duration i.e. 2–3 days. These 21 heavy rain spells were
subjected to DD analysis using GIS technology and the results showed that eight most severe
rainstorms occurred over Uttarakhand State (see Table 6). Table 6 also gives the average

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raindephs (mm) for 1 to 3 day durations of the rainstorm along with centre and date of

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occurrence mentioning envelope or Standard Project Storm (SPS) rain depths at the end. DD
curves for the eight most severe rainstorms over the Uttarakhand region are shown in Fig. 9.
an
It is seen from Table 6 and Fig. 9 that of all the severe rainstorms, the 27–29
September 1924 rainstorm has recorded higher rain depth (SPS) values, forming an envelope
M

of all the rainstorms. This rainstorm was caused due to a cylonic storm that originated in the
southeast Bay of Bengal. After crossing the east coast near the north of Chennai, it traveled in
d

a northwesterly direction and recurved in a northeasterly direction near the south of Gujarat
e

due to movement of Western Disturbances in the extreme north of J&K (see Fig. 10). This
resulted in heavy rainfall over Uttarakhand State. It is also seen from Fig. 10 that heavy
pt

rainfall over the state mostly occurs because of curvature of most of the storms due to the
ce

Himalayas during the monsoon season.

The spatial distributions of some of the most severe rainstorms are shown in Figure
Ac

11. The spatial distribution shows that rainstorms occurred in the months of September or
October have two rain centres, with wide distribution of rainfall. The northern and
northwestern parts of the state shows comparatively less rainstorm activity. But when western
disturbances are also active during the monsoon season this region also receives heavy
rainfall, as happened in the rainstorms of September 1914 (Figure 11(d)), September 1924
(Figure 11(b)) and September 1963 (Figure 11(g)). The northern and northeastern parts are
devoid of heavy rainfall activity due to their high orographic nature.
 14

The comparison of average rain depths yielded by these severe rainstorms with the
past severe rainstorms revealed that the September 1880 rainstorm was the most severe
rainstorm to have occurred in the close vicinity of Uttarakhand State near the foothills of the
Himalayas. The storm was analysed by Dhar et al. (1975), who showed that this rainstorm,
with its centre at Nagina, recorded 823.0 mm on 18 September 1880, there are eight more
stations which recorded more than 300 mm of rainfall in one day (Table 7). This storm
occurred over major parts of Uttarakhand and Uttar Pradesh (Figure 12) along with some
parts of Himachal Pradesh and Haryana, covering more than 100 000 km2 of the area. The

t
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DAD rain depths of this storm up to 50 000 km2 area are given in Table 8.

8. Discussion

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As mentioned earlier, widespread very heavy to extremely heavy rainfall occurred over
Uttarakhand and its neighbouring states during 16–18 June 2013, causing flash floods in the
an
Saraswati and Mandakini rivers in Rudraprayag District of Uttarakhand (Figures 13 and 14),
bringing landslides, large-scale loss of lives and damage to property. The noteworthy rainfalls
recorded by some of the stations were: 220 mm at Dehra Dun on 16 June, 370 mm at Dehra
M

Dun and 237 mm at Mukteshwar on 17 June, and 207 mm at Mukteshwar on 18 June.

d

The nearby areas received similar heavy rainfall in the range of 100–200 mm. The higher
altitude (above 3000 m) regions of Kedarnath, Gangotri and Badrinath received unusually
e

heavy rainfall. The Wadia Institute of Himalayan Geology (WIHG) meteorological

pt

observatory at Chorabari Glacier camp (3820 m a.s.l.) recorded 210 mm rainfall in 12 hours
between 15 June (17:00 h) and 16 June (05:00 h) 2013. On 16 June 2013 alone (from 05:00 h
ce

to 17:00 h), 115 mm rainfall was recorded, making 325 mm rain in 24 h (Dobhal et al. 2013).
Heavy rainfall due to cloud burst affected Tehri, Chamoli, Rudraprayag and Uttarkashi
Ac

districts, where 21 bridges collapsed, including eight bridges in Chamoli and seven in
Pithoragarh districts (See Fig. 14).

There are reports of loss of large number of human lives and damage to the property
and livestock. The Chorabari Lake (3960 m a.s.l.) also known as Gandhi Sarovar Lake, is a
snow melt and rain fed lake, located about 2 km upstream of Kedarnath town is
approximately 400 m long, 200 m wide having a depth of 15–20 m. The bursting of this lake
led to its complete draining within 5–10 min as reported by the staff of the WIHG, which
 15

were present in WIHG camp at Chorabari Glacier on 16 June and early morning of 17 June
2013. The heavy rainfall together with melting of snow in the surrounding Chorabari Lake
washed off both the banks of the Mandakini River causing massive devastation to the
Kedarnath town.

However, as shown in Table 5, the Uttarakhand state has experienced more than 300
mm of rainfall in the month of June in a short time period. Therefore, besides the heavy
rainfall, the other factors which together made the situation worse are - a) all the regions

t
rip
around the Kedarnath are geologically prone to landslides, b) There are sediments and debris
from upper regions which enroute from the higher regions carried down by the flowing
volume of water, c) There was fresh and excess snowfall on the upper glacial regions before

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the rainfall actually hit and d) the warmer rainfall, along with its rainwater, melted the snow

us
which created a wall of flash flood and the disaster claimed thousands of lives.
an
8. Conclusions
M
In view of the destruction and damage caused by June 2013 heavy rainfall over the
region, an attempt has been made to study the extreme rainfall events experienced by the
Uttarakhand state during 1901 to 2013. The analysis revealed that –
e d

1. The maximum frequencies of extreme one-day rainfall was recorded in the month of
pt

October (75) and lowest frequency in the month of November (2).

2. Most of the stations recorded one-day extreme rainfall during May to October in the
ce

range of 100 to 300 mm, except Khadrala station (Dist. Mahasu) which recorded one-
day extreme rainfall of more than 700 mm.
Ac

3. About 12 stations inside the Uttarakhand recorded more than 400 mm of rainfall in 1-
day mostly in July, August and September monsoon months. Of these, Garbyang (in
January) and Nainital stations recorded more than 500 mm of extreme 1-day rainfall.

4. Stations at higher altitude recorded extreme rainfall during October and January
months whereas plain area stations recorded during June to September monsoon
months.
 16

5. The magnitude of extreme 1-day rainfall was higher in those stations that are located
in the windward side than those are falling in the leeward side which shows the
influence of orography over the rainfall distribution of the region.

6. Decadal analysis of extreme rainfall showed that large numbers of 1-day extreme
rainfall events (34) have been recorded during 1961-1970 decade.

7. Frequency and trend analysis of extreme 1-day rainfall events showed that there is
decreasing trend in magnitude of extreme rainfall in 42% of Uttarakhand stations

t
especially after 1970.

rip
8. There are good numbers of stations recorded highest 1-day rainfall of greater
magnitude in the past than recorded during June 2013.

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9. Although heavy rainfall of 2013 occurred for the first time in June was mostly

us
because of cloud burst. The heavy rainfall became severe due to rapidly melting of
glacier in the upper reaches of Chorabari Lake releasing large amount of accumulated
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water from the lake as there was no outlet in the lake. In addition to this, man made
interventions and poor planned development in this region is also responsible for such
M
evidences (Dobhal et al, 2013).

Acknowledgement
d

Authors are thankful to Director, IITM, Pune for his keen interest and encouragement
e

for carrying out this study. Authors express their sincere thanks to all the Himalayan Project
pt

Authorities, Forest Departments, and India Met. Dept. (IMD), Pune for supplying the relevant
rainfall data.
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References
Ac

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 20

Table 1. Monthly, seasonal and annual frequency distribution of 1-day extreme rainfall.

Rainfall Monthly highest 1-day rainfall (mm) frequency Seasonal frequency Annual
(mm) frequ-
Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec J-F M-M J-S O-D ency
<100 74 73 70 85 72 34 14 12 17 42 93 80 62 50 6 36 2
100–200 19 17 25 10 19 45 43 49 41 44 3 12 26 38 32 46 27
200–300 2 3 2 2 4 15 26 28 31 10 1 3 5 7 37 12 40
300–400 3 2 3 8 6 3 1 2 2 10 1 14
400–500 1 6 5 1 10 1 9
500–600 1 2 1 2 3
600–700 1 1 1

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>700 1 1 1

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Table 2. Frequency of extreme 1-day rainfall during different seasons in and around the
Uttarakhand.

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Season Jan.–Feb. Mar.–May Jun.–Sep. Oct.–Dec.
Frequency of extreme
98 98 99 96
1-day rainfall
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Table 3. Highest 1-day rainfall (>400 mm) recording stations in Uttarakhand (1901–2013).

Highest 1-
Altitude Date of
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No. District Station day Rainfall
(m) Occurrence
(mm)
1 Dehradun Dehradun (O) 682 487.0 25/07/1966
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2 Dehradun Rajpur 975 440.4 25/08/1954

3 Uttar-Kashi Kharsali (O) 2591 400.8 15/09/1963
e

4 Tehri-Garhwal Mukhim 1981 450.0 05/09/1995

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5 Pithoragarh Askote 1372 450.0 05/09/1982

6 Pithoragarh Berinag 1676 475.0 06/09/1965
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7 Pithoragarh Garbyang 3400 576.0 30/01/1968

8 Udham Singh Nagar Bazpur 215 406.4 03/10/1934
9 Udham Singh Nagar Khatima 203 405.6 13/09/1972
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10 Nainital Haldwani 348 413.0 11/07/1970

11 Nainital kaladhungi 393 413.0 10/07/1970
12 Nainital Nainital 2020 509.3 22/09/1958
 21

Table 4. Monthwise statistics of highest 1-day rainfall and their date of occurrence in the
Uttarakhand region.

Highest 1-day
Month Station Altitude Date of
Rainfall
(m) Occurrence
(mm)
January Khadrala 2957 762.0 28/01/1968
February Khadrala 2957 482.6 16/02/1963
March Chini (Kalpa) 2781 479.0 03/03/2002
April Garbyang 3400 279.8 04/04/1969

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04/05/1971
May Chini (Kalpa) 2781 378.0
& 02/05/1989
June Dhampur 235 400.0 25/06/1989

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July Dehradun (O) 682 487.0 25/07/1966
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August Dhampur 235 600.0 30/08/1991

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Thakurdwara 244 600.0 11/08/1991
September Dhampur 235 772.2 18/09/1880
October Simla (O)
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2202 800.0 19/10/1899
November Khadrala 2957 279.4 21/11/1967
December Kilba 2180 609.6 27/12/1958
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Table 5. Magnitude of extreme one-day rainfall (mm) for stations in and around Uttarakhand.
d

Extreme one-day rainfall (mm) for stations

Months /
Inside Uttarakhand Around Uttarakhand
Seasons
e

Lowest Highest Lowest Highest

Jan 18.0 576.0 24.4 762.0
pt

Feb 17.8 381.8 12.7 482.6

Mar 0.8 288.0 15.3 254.0
Apr 3.0 279.8 17.8 200.0
ce

May 5.0 370.0 7.6 378.0

Jun 1.6 362.0 52.0 400.0
Jul 48.3 487.0 38.9 470.0
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Aug 41.2 398.8 51.1 600.0

Sep 40.2 475.0 78.7 400.6
Oct 27.9 307.3 23.1 241.2
Nov 0.4 134.0 6.3 279.4
Dec 3.2 288.0 19.0 609.6
Jan-Feb 25.0 576.0 36.0 762.0
Mar-May 16.4 370.0 17.8 378.0
Jun-Sep 53.3 487.0 88.1 600.0
Oct-Dec 27.9 307.3 30.0 609.6
Annual 81.3 576.0 134.6 762.0
 22

Table 6. Average rain depth (mm) yielded by severe rainstorms over Uttarakhand in the
period 2001–2013.

Average rain depth (mm) for 1- to 3-day durations

No. Rainstorm period with date of occurrence and centre
1-day 2-day 3-day
1 21–23 August 1901 95.0 (21/08) 157.6 (21-22/8) 199.1 (21–23/08)
Nainital Nainital Nainital
2 1–3 October 1910 124.4 (02/10) 249.4 (2–3/10) 288.2 (1–3/10)
Landsdown Landsdown Landsdown

t
18–20 September

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3 124.7 (18/09) 234.1 (18–19/09) 273.8 (18–20/09)
1914 Nainital Nainital Nainital

4 9–11 October 1956 120.9 (09/10) 178.5 (9–10/10) 233.0 (9–11/10)

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Nainital Nainital Nainital
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27–29 September

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5 142.7 (29/09) 265.3 (28–29/09) 320.6 (27–29/09)
1924 Landsdown Landsdown Landsdown

69.6 (21/08) 108.4 (20–21/08) 137.8 (20–22/008)

6 20–22 August 1963
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Haldwani Kilpuri Nainital
15–17 September
7 106.9 (16/09) 162.0 (15–16/09) 175.4 (15–17/09)
1963 Nainital Nainital Nainital
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22–24 September
8 63.0 (24/09) 113.2 (23–24/09) 158.0 (22–24/09)
1969 Khatima Khatima Rudrapur
d

9 85.1 (10/07) 147.7 (9–10/07) 181.2 (8–10/07)

e

8–10 July 1990

Rudrapur Haldwani Narendranagar
pt

Envelope (SPS)
142.7 265.3 320.6
rain depth (mm)
ce
Ac
 23

Table 7. Extreme 1-day rainfall (mm) inside and nearby Uttarakhand (prior to 1901).
1-day rain
District Station Date of occurrence
fall (mm)
Uttarakhand
Champawat Champawat 389.9 27/09/1897
Ranikhet 304.8 18/08/1880
Kausanie 200.1 03/10/1910
Chamoli Tapovan 190.5 27/07/1952
Dehradun Rajpur 440.4 25/08/1954
Chakrata 246.4 29/07/1871
Bhojpur 381.0 29/07/1890

t
Raipur 294.6 03/09/1924

rip
Mussoorie 439.4 19/08/1890
Nainital Tanakpur 305.1 20/08/1961
Rudrapur 307.1 25/07/1907
Bazpur 406.4 03/10/1934

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Kilpuri 330.2 06/08/1885
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Gadarpur 274.3 05/07/1950

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Kashipur 315.0 02/10/1934
Kathagodam 306.6 15/07/1897
Nagla 325.6 20/09/1922
Nainital 509.3 22/09/1958
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Somerfold Orchard 242.1 28/09/1924
Pauri Garhwal Pauri 224.5 18/08/1921
Srinagar 190.5 18/09/1880
Kotdwara 349.0 27/08/1892
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Pithorgarh Pithorgarh 200.7 26/06/1921
Tehri Garhwal Tehri (O) 194.8 12/12/1957
Ghuttu 345.7 10/07/1957
Uttarkashi Dharasu 90.0 29/09/1950
d

Uttar Kashi (Barahat) 120.0 26/09/1964

Jamuna Chettty 175.0 16/07/1962
e

Rana 281.0 16/07/1963

Kharsali 400.8 15/09/1963
pt

Uttar Pradesh
Bareilly Bareilly 378.5 09/07/1878
ce

Nawabganj 533.4 07/07/1882

Aonla 302.5 31/07/1958
Faridpur 312.4 31/08/1810
Baheri 477.5 29/07/1871
Ac

Pandhera 689.5 30/08/1961

Mirganj 358.1 29/06/1870
Bijnor Nagina 823.0 18/09/1880
Dhampur 772.2 18/09/1880
Najibabad 723.9 18/09/1880
Muradabad Muradabad 315.0 18/07/1883
Thakurdwara 264.2 12/07/1888
Hasanpur 278.9 23/06/1933
Sambhal 321.1 11/08/1919
Bilari 287.0 28/07/1873
Meerut Meerut (O) 227.0 17/09/1880
Sardhana 345.4 18/09/1880
Mawana 393.7 18/09/1880
 24

Baghpat 314.7 21/08/1952

Ghaziabad 231.7 16/09/1963
Hapur 269.2 22/07/1867
Dasna 274.3 14/09/1957
Saharanpur Saharanpur 266.7 02/07/1895
Roorkee (O) 284.7 17/09/1880
Nakur 292.1 02/07/1895
Hardwar 495.3 18/09/1880
Muhammadpur 452.1 17/09/1880
Nayashar 292.1 06/07/1887
Jarauda 330.2 19/09/1933
Kalsia 323.9 09/08/1942

t
Kaunkhera 210.8 03/07/1956

rip
Salimpur 284.7 19/09/1933
Muzaffarnagar Kairana 287.0 22/07/1867
Budhana 244.9 16/07/1900
Jaoli Jansath 406.4 17/09/1880

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Pilbhit Pilbhit (Cutcherry) 345.4 02/08/1879
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Himachal Pradesh

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Simla Kotarh 787.9 18/02/1877
Kotkhai 711.7 18/02/1877
Simla (O) 800.0 19/10/1899
an
Table 8. Average rain depths (cm) yielded by the 17–18 September 1880 rainstorm over
different standard areas (Dhar et al. 1975).
M

Storm centre Average rain depth (cm) over 102 km2 area
Rainstorm
(District) Point 1 5 10 20 50 100 200 500
d

Nagina
18/09/1880 (Bijnor) 82.3 82.0 80.0 77.5 73.6 62.8 51.5 40.5 26.3
e

Nagina
17–18/09/1880 (Bijnor) 104.1 103.5 100.0 99.1 95.9 86.8 76.8 63.0 41.4
pt
ce
Ac
 25

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an
Figure 1 Map of Uttarakhand showing topography, high peaks, rivers and G/D sites on rivers.
M
e d
pt
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Ac
 26

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an
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Figure 2 Map of Uttarakhand showing two sub-divisions, rivers and rainfall stations and their
altitudes (m a.s.l.).
e d
pt
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 27

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an
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d

Figure 3 Interaction zone of severe rainfall due to cyclonic and Western Disturbances.
e
pt

80
Frequency of Highest 1-day Rainfall

ce

70
60
50
Ac

40

30

20
10

0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Months

Figure 4 Monthly frequency of highest 1-day rainfall (≥100 mm).

 Downloaded by [New York University] at 10:08 15 March 2016

Annual 1-day extreme rainfall (mm)

100
200
300
400
500
600
700

0
Hardwar (H)
Roorkee
Bhogpur
Dehradun (O)
Mussoorie (O)
Ac
Raipur
Rajpur
Ambari
Chakrata Kalsi
Hardwar (H), 495.3

Uttar-Kashi
Uttar-Kashi (O)
Jamuna Chatty
ce
Kharsali (O)
Rana (O)
Dehradun (O), 487.0

Rajgarhi
Bironkhol
kotdwara
Landsdown
Pauri
Srinagar
pt
Deoprayag
Dhanolti
e Mukhim
Narendranagar
Tehri
Tehri-garhwal
d Dharasu (T)
Ghuttu (T)
Karna prayag
Keerti Nagar
Okhimath
Chamoli
M Ghangaria (O)

Stations
Joshimath
Lokpal(O)
Tapovan
Askote
Berinag
Chaukuri
Dharchula
Garbyang
Munsiyari
an
Pithoragarh
Berinag, 475.0

Tijjam
Champawat
Bazpur
Gadarpur
Garbyang, 576.0

Khatima
Rudrapur/Kitcha
Almora
us
Ranikhet
Kausani
Haldwani
c kaladhungi
Kashipur
Kathgodam
Figure 5 Variation of extreme 1-day rainfall with altitude over Uttarakhand.

Kilpuri
Mukteshwar

Figure 6 Spatial distribution of extreme 1-day rainfall in and around Uttarakhand.

Nagla
Nainital
Nainital (O)
rip
Ramnagar
Nainital, 509.3

Tanakpur
28

t
500
1000
1500
2000
2500
3000
3500
4000
4500
5000

Altitude (m)
 29

y = -0.1048x3 + 1.5831x2 - 4.4776x + 5.0505

40

No. of Extreme Events recorded

2
R = 0.4545
35
30
25
20
15
10

t
5

rip
0
1901-1910

1911-1920

1921-1930

1931-1940

1941-1950

1951-1960

1961-1970

1971-1980

1981-1990

1991-2000

2001-2010

2011-2013*
c
Downloaded by [New York University] at 10:08 15 March 2016

us
Decades

Figure 7 Decadal frequency of 1-day extreme rainfall events (although 2011–2013 is not a
an
full decade, the number of extreme events in these three years has been shown by way of
comparison).
M
e d
pt
ce
Ac
 30

300 y = -0.0069x 2 + 0.7455x + 112.11 500 y = -0.0061x 2 + 0.5724x + 152.97

Roorkee R2 = 0.0189 Dehradun R2 = 0.0136
400
200
300

200
100
100

0 0

1901
1911
1921
1931
1941
1951
1961
1971
1981
1991
2001
2011
1901
1911
1921
1931
1941
1951
1961
1971
1981
1991
2001
2011

t
rip
400 y = 0.0002x 2 - 0.5401x + 170.47 400 y = -0.0393x 2 - 2.2701x + 180.02
Ambari R2 = 0.0326 Mussoorie R2 = 0.228

300 300

c
Downloaded by [New York University] at 10:08 15 March 2016

200

us
200
Extreme 1-day rainfall (mm)

100
100

0
an 0
1960

1966

1972

1978

1984
1901

1911

1921

1931

1941

1951

1961

1971

M
300 y = -0.0184x 2 + 1.2145x + 90.61 200 y = -0.0011x 2 - 0.0963x + 85.909
Birankhol R2 = 0.1904 Pauri R2 = 0.0367

200
d

100
100
e
pt

0 0
1901
1911
1921
1931
1941
1951
1961
1971
1981
1991

1901

1911
1921

1931

1941
1951

1961

1971
1981
ce

200 y = 0.0007x 2 - 0.1737x + 86.303 200 y = 0.0016x 2 - 1.2344x + 115.66

R2 = 0.0105
Dhanolti R2 = 0.1756
Srinagar
Ac

100 100

0 0
1955

1965

1975

1985

1995
1901

1911

1921

1931

1941

1951

1961

1971

Years
Figure 8 Yearly variation of extreme 1-day rainfall with trend for stations in Uttarakhand.
 31

300 y = -0.017x 2 + 1.5009x + 78.756 300 y = -0.0012x 2 + 0.0117x + 67.66

Okhimath R2 = 0.1319 R2 = 0.0068
Joshimath

200 200

100 100

0 0
1901
1911
1921
1931
1941
1951
1961
1971
1981
1991

1901
1911
1921
1931
1941
1951
1961
1971
1981
1991

t
rip
2
500 y = -0.1712x 2 + 7.7824x + 73.393 300 Chaukuri y = 0.0177x - 2.512x2 + 165.91
R2 = 0.0481 R = 0.4307
Askote
400
200

c
300
Downloaded by [New York University] at 10:08 15 March 2016

Extreme 1-day rainfall (mm)

200

us
100

100

0 0
an 1901

1911

1921

1931

1941

1951

1961

1971
1950

1960

1970

1980

1990

200 y = -0.0057x 2 + 0.4665x + 74.284 300 y = -0.0083x 2 + 0.5225x + 79.235

Pithorgarh R2 = 0.0248 Almora R2 = 0.0877
M

200

100
d

100
e
pt

0 0
1901

1911

1921

1931

1941

1951

1961

1971

1981

1991
1901
1911

1921
1931

1941
1951

1961

1971
1981

1991
ce

500 y = -0.0378x 2 + 2.416x + 173.35 300 y = -0.0096x 2 + 0.9193x + 118.37

Nainital R2 = 0.2187 Ramnagar R2 = 0.0143
400
200
300
Ac

200
100

100

0 0
1901

1911

1921

1931

1941

1951

1961

1971

1981

1991
1901

1911

1921

1931

1941

1951

1961

1971

1981

1991

Years

Fig.8 continued
 32

350

300
21-23/08/1901

Average Raindepths (mm) 250 01-03/10/1910

18-20/09/1914
200 09-11/10/1956

150 27-29/09/1924
20-22/08/1963
100 15-17/09/1963
08-10/07/1990

t
50

rip
0
1-day 2-day 3-day
Duration (Days)

c
Downloaded by [New York University] at 10:08 15 March 2016

Figure 9 Depth–duration (DD) curves for most severe rainstorms over Uttarakhand.

us
an
M
e d
pt
ce
Ac

Figure 10 Tracks of most severe rainstorms over Uttarakhand.

 Downloaded by [New York University] at 10:08 15 March 2016

(c)
(b)

(a)
Ac
ce
pt
e d
M
an
us
c rip
33

t
 (e)(d)
(f)
(g)
34

t
c rip
Downloaded by [New York University] at 10:08 15 March 2016

us
an
M
e d
pt

Figure 11 Spatial distribution (3-day) of rainstorms over over Uttarakhand State: (a) 27–29
ce

September 1924; (b) 21–23 August 1901; (c) 1–3 October 1910; (d) 18–20 September
1914; (e) 9–11 October 1956; (f) 20–22 August 1963; and (g) 15–17 September 1963.
Ac
 35

t
c rip
Downloaded by [New York University] at 10:08 15 March 2016

us
an
M

Figure 12 Two-day isohyetal pattern of the 17–18 September 1880 rainstorm.

e d
pt
ce
Ac
 36

t
c rip
Downloaded by [New York University] at 10:08 15 March 2016

us
an
M

Figure 13 Before and after satellite images of the Indian National Remote Sensing Centre
d

(NRSC) showing the status at Kedarnath valley with downstream overflow of the Mandakini
River.
e
pt
ce
Ac
 37

t
c rip
Figure 14 A submerged bridge over the Ganga in Rudraprayag, Uttarakhand
Downloaded by [New York University] at 10:08 15 March 2016

(www.nidm.gov.in).

us
an
M
e d
pt
ce
Ac