sub-basins, Spiti, Parechu and Tsarap Chu. The
searching literature on the study area indicates
that there is no published data on the morphometry based on remote sensing and GIS
techniques. Therefore, the present study aims at
morphometric analysis on basin level by using
remote sensing and GIS techniques. The Spiti
river originates from Kunzum range, and Tegpo
and Kabzian streams are its tributaries. Water
draining the famous Pin valley area is also a part
of the Spiti river system. Its position across the
main Himalayan range deprives it from the
benefit of the South-West monsoon that causes
widespread rain in most parts of India from June
to September. Most of the rivers in the area are
perennial rivers, originating from glaciers and
snow fields (Singh and Kumar 2014a).
The river attains peak discharge in late summers due to glacier melting. Owing to faster rate of
snow and ice melting, the accumulation of water in
the newly formed glacial lakes has been increasing
rapidly and resulted in sudden discharge of large
volume of water and debris, causing flooding in
the downstream (Singh and Kumar 2014b). The
present study will further help in assessing flood
vulnerability to downstream dwellers. After flowing through Spiti valley, the Spiti river meets
Satluj at Namgia in Kinnaur district traversing a
length of about 150 km from the north-west;
beyond that it flows in the south-west direction in
Himachal Pradesh. The larger tributaries of the
Spiti flow through valleys resembling much that of
the main river but toward their junctions with it
have to force their way in deep narrow chasms
through the rocky walls that rise on either side of
the main valley. The main tributaries are the Pin on
the right bank and the Sampa, Shila and Lingti on
the left. The Pin which rises in south-west corner
of the Spiti and drains fully one-quarter of its total
area is almost equal to the Spiti river in volume at
their point of junction.
16.2 The Study Area
Spiti river basin is located between 31°42′ and
32°58′ N latitude and 77°21′ and 78°35′ E longitude with an area of 7,589 sq. km. It is
bordered by Ladakh in the north, Tibet in the
east, Kinnaur and Kullu in the south and Lahaul
in the west (Fig. 16.1). Owing to its location on
the leeward side of the greater Himalayan ranges,
the lack of precipitation and minimum elevations
of over 3350 m, Spiti has a bleak, awe-inspiring
terrain, seemingly devoid of vegetative cover and
one of the harshest climates in the world
(Gazetteer of the Kangra District, 1897). Spiti is
home of lofty mountain ranges of an average
elevation of 18,000 feet. The carrying capacity of
Spiti valley is low due to harsh climatic condition
and rugged topography. Population is mainly
concentrated in a few favorable pockets which
are confined to valley. Therefore, large area of
Spiti, especially with steep slopes and higher
altitude, is uninhabited (Pankaj et al. 2018).
16.3 Data Set and Methodology
Drainage map and spilt drainage map of the Spiti
river basin has been prepared by using Global
Digital Elevation (GDEM) with 30 m resolution.
The tiles of the Global Digital Elevation Model
(GDEM) have been merged using image processing
software Erdas Imagine 14. Then, flow direction,
flow accumulation, stream order and watershed and
so on have been simulated using hydrological tools
such as ArcGIS 10.1. The morphometric parameters
of all the three sub-basins have been calculated
using ArcGIS 10.1 software for digitizing and
computation purposes and to generate the output.
The study analyzed 14 morphometric parameters of
the Spiti river basin (Table 16.1).
16.4 Flow Direction
and Accumulation
The flow direction tool is used to determine the
direction of flow from every cell in the raster
image. This tool takes a surface as input and
outputs a raster showing the direction of flow out
of each cell. The direction of flow is determined
by the direction of steepest descent, or maximum
drop, from each cell. This has been calculated as
follows:
214
A. Husain and P. Kumar
searching literature on the study area indicates
that there is no published data on the morphometry based on remote sensing and GIS
techniques. Therefore, the present study aims at
morphometric analysis on basin level by using
remote sensing and GIS techniques. The Spiti
river originates from Kunzum range, and Tegpo
and Kabzian streams are its tributaries. Water
draining the famous Pin valley area is also a part
of the Spiti river system. Its position across the
main Himalayan range deprives it from the
benefit of the South-West monsoon that causes
widespread rain in most parts of India from June
to September. Most of the rivers in the area are
perennial rivers, originating from glaciers and
snow fields (Singh and Kumar 2014a).
The river attains peak discharge in late summers due to glacier melting. Owing to faster rate of
snow and ice melting, the accumulation of water in
the newly formed glacial lakes has been increasing
rapidly and resulted in sudden discharge of large
volume of water and debris, causing flooding in
the downstream (Singh and Kumar 2014b). The
present study will further help in assessing flood
vulnerability to downstream dwellers. After flowing through Spiti valley, the Spiti river meets
Satluj at Namgia in Kinnaur district traversing a
length of about 150 km from the north-west;
beyond that it flows in the south-west direction in
Himachal Pradesh. The larger tributaries of the
Spiti flow through valleys resembling much that of
the main river but toward their junctions with it
have to force their way in deep narrow chasms
through the rocky walls that rise on either side of
the main valley. The main tributaries are the Pin on
the right bank and the Sampa, Shila and Lingti on
the left. The Pin which rises in south-west corner
of the Spiti and drains fully one-quarter of its total
area is almost equal to the Spiti river in volume at
their point of junction.
16.2 The Study Area
Spiti river basin is located between 31°42′ and
32°58′ N latitude and 77°21′ and 78°35′ E longitude with an area of 7,589 sq. km. It is
bordered by Ladakh in the north, Tibet in the
east, Kinnaur and Kullu in the south and Lahaul
in the west (Fig. 16.1). Owing to its location on
the leeward side of the greater Himalayan ranges,
the lack of precipitation and minimum elevations
of over 3350 m, Spiti has a bleak, awe-inspiring
terrain, seemingly devoid of vegetative cover and
one of the harshest climates in the world
(Gazetteer of the Kangra District, 1897). Spiti is
home of lofty mountain ranges of an average
elevation of 18,000 feet. The carrying capacity of
Spiti valley is low due to harsh climatic condition
and rugged topography. Population is mainly
concentrated in a few favorable pockets which
are confined to valley. Therefore, large area of
Spiti, especially with steep slopes and higher
altitude, is uninhabited (Pankaj et al. 2018).
16.3 Data Set and Methodology
Drainage map and spilt drainage map of the Spiti
river basin has been prepared by using Global
Digital Elevation (GDEM) with 30 m resolution.
The tiles of the Global Digital Elevation Model
(GDEM) have been merged using image processing
software Erdas Imagine 14. Then, flow direction,
flow accumulation, stream order and watershed and
so on have been simulated using hydrological tools
such as ArcGIS 10.1. The morphometric parameters
of all the three sub-basins have been calculated
using ArcGIS 10.1 software for digitizing and
computation purposes and to generate the output.
The study analyzed 14 morphometric parameters of
the Spiti river basin (Table 16.1).
16.4 Flow Direction
and Accumulation
The flow direction tool is used to determine the
direction of flow from every cell in the raster
image. This tool takes a surface as input and
outputs a raster showing the direction of flow out
of each cell. The direction of flow is determined
by the direction of steepest descent, or maximum
drop, from each cell. This has been calculated as
follows:
214
A. Husain and P. Kumar