Linear ordering. However, according to Strahler, each

Linear Properties:

Linear
properties of the drainage basin deals with channel pattern of the drainage
network. Topographic characteristics of the stream network analyses by using
linear aspects of the drainage network. Total number of streams, their
hierarchical order, length of all streams and their interrelationship analyze
in linear properties. Sinuosity represents nature of the flow path of drainage
basin (Akram Javed et al., 2009; Pareta and Pareta, 2012). Such type of linear
properties are useful in different types of watershed analysis, these aspects
are discussed as follows.

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Stream Ordering:

Stream
ordering is the first step in morphometric analysis. Hierarchical position of
streams within the drainage basin studies in stream ordering (Leopold et al.,
1964). The ability of erosion is totally depending upon the linear parameters
of the basin (V.S.S. Kiran and Y.K. Srivastava) and all the linear parameters
can be calculated after the stream ordering only. Numbers of scientist have
taken efforts a methodology for performance of the stream ordering. Gravelius,
Horton’s reclassification method for stream ordering (1932, 1945), Strahler’s
stream segment method (1952), Shreve’s Stream-Link Magnitude Method (1966,
1967) these are the important methods for stream ordering. However, according
to Strahler, each finger tip channel is designated as first order. When two
first order segments meet each other they forms second order and so on. If
lower order stream segment connect to higher order stream segment the
classification not affected in such conditions. Hierarchical order increases
only when two stream segments of equal order meet and form a junction
(Strahler, 1969). This method is simple and easy for application. Hence,
Strahler’s stream segment method (1952) is universally accepted for obtaining
the stream order (Usha Chirala et al. 2012).

Bifurcation Ratio (Rb):

Horton
(1945) considered Rb as an index of reliefs and dissections. Strahler (1957)
demonstrated that Rb shows only a small variation for different regions with
different environmental aspects where powerful geological control dominates.
Lower Rb values are the characteristics of structurally less disturbed
watersheds without any distortion in drainage pattern (Nag, 1998). Irregular Rb
values do not subscribe to Horton’s law of stream numbers which probably
represent local variations in the drainage development. If the mean bifurcation
ration (Rbm) observed high it indicates the structural control on drainage
development (Akram Javed et al., 2009; Nageswara et al., 2010; Syed and Khan, 2013).

Stream Number (Nu):

Stream
numbers according to stream order forms the ‘law of stream number’ stated by
Horton, R. E. (1945). According to the law the number of streams of different
orders in a given drainage basin tends closely to approximate an inverse
geometric ratio. The law also stated that the number of streams negatively
correlated with the order. The stream numbers decreases with increasing stream
order (Horton, 1945; Syed and Khan,
2013).  Total stream numbers of
the basin can be find out using total stream segments and constant bifurcation
ratio.

Length of Overland Flow:

It is designated by Lg. Horton (1945) used this term to refer to the
length of the run of the rainwater on the ground surface before it is localized
into definite channels. Since this length of overland flow, at an average, is
about half the distance between the stream channels, Horton, for the sake of
convenience, had taken it to be roughly equal to half the reciprocal of the
drainage density. The lowest value of length of overland flow indicates young
topography will low surface runoff (Pareta and Pareta, 2012).

 

Stream
length (Lu):

Stream length is measured from
the farthest drainage divide to the mouth of a river. Stream length is one of
the significant features of the basin as it reveals surface run-off
characteristics. Smaller lengths streams indicate that the area is with high
slopes. Longer lengths streams indicate low gradient. Usually, the total length
of stream segments is highest in first order streams, and it decreases as the
stream order increases (Singh and Singh, 1997; Vittala et al., 2004 and Chopra
et al., 2005).

Mean
stream length (Lsm):

Mean stream length (Lsm) is a characteristic property related to
the drainage network components and its associated basin surfaces (Strahler, 1964).
This has been calculated by dividing the total stream length of order (u) by
the number of streams of segments in that order (Nongkynrih and Husain, 2011).   

Stream
length ratio (RL):

Stream length ratio (RL) is the ratio of the mean length of the
one order to the next order of the stream segments. Total stream length of a
given order is inversely related to stream order,

i.e., total stream length decreases from the lower order to the
respective higher orders. This change might be credited to variation in slope
and topography, indicating the youth stage of geomorphic development in the
streams of the study area (Singh and Singh, 1997; Nongkynrih and Husain, 2011
and Vittala et al., 2004).

3.2. Areal Properties:

Basin
Shape:  Basin shape is the ratio of the square of
basin length (Lb) to the area of the basin (A). Lower values interpret weaker
flood discharge periods, whereas higher values indicate sharply peaked flood
discharge (Akram Javed et al., 2009)  Basin
Perimeter, Basin Length and Basin Area:

Basin perimeter is the length outer boundary of the watershed that
enclosed its area and it is indicated by ‘P’. It is measured along the divide
between watersheds and it may be used as an indicator of watershed size and
shape (Pareta and Pareta, 2012).

Basin length (Lb) is considered as distance between the two either
points of the basin. Different geographers define the concept in different way,
like as Schumn (1956) defined the basin length as the longest dimension of the
basin parallel to the principal drainage line, Gregory et al. (1968) defined
the basin lengths as the longest in the basin in which are end being the mouth
and Gardiner (1975) defined the basin length as the length of the line from a
basin mouth to a point on the perimeter equidistant from the basin mouth in
either direction around the perimeter. Researcher can used any method according
to convenience and need of the requirement. But majority of the Schumn’s scheme
is high as compare to another one (Pareta and Pareta, 2012). 

Basin area is (A) the hydrological unit
which contributes the runoff water into unique stream. All these factors are
most significant in analysis process of the further areal aspects (Singh
Vineesha and Singh U. C., 2011)

Stream/
Drainage Frequency (Fs): It
is the total number of stream segments of all orders per unit area (Horton,
1932). Stream frequency indicates positive correlation with the drainage
density of all the sub watersheds. It suggests increase in stream population
with respect to increase in drainage density (Akram Javed et al. 2009).  Drainage
Density: It denotes by
‘D’. It indicates closeness of spacing between channels and measures total
stream lengths of per unit area. It is the ratio of total stream length of all
stream segments in given drainage basin to the total area of the drainage basin
(Horton, 1945). It is stated as, Dd = Lk / Ak,             Where, Dd =
Drainage density, Lk = total length of the all stream segments of
the drainage basin, and Ak = total area of the basin. Calculation of
Drainage density by Horton’s method yields only a single value of drainage
density for entire basin. Hence, it cannot apply for the analysis of spatial
variation in different part of drainage basin.Value of drainage density is related and affected by precipitation
effectiveness (M. A. Melton, 1957), vegetation index (R. J. Chorley, 1957),
permeability of terrain (C. W. Carlston, 1963), climatic characters (C. A.
Cotton), rainfall intensity (R. J. Chorley and M. A. Morgan, 1962; M. A.
Melton, 1957) rock type and structure (Savindra Singh and Renu Srivastava,
1974) etc. Drainage density helps to understand the region with respect to
permeability of material; vegetation cover and relief factor (Akram Javed et
al. 2009). Lower value of drainage density interprets region as highly
permeable material with vegetation cover and low relief. Where high value of D
is indicating weak and impermeable subsurface material, sparse vegetation and
mountain relief (Nautiyal, 1994; Nongkynrih and Husain, 2011).Drainage
Texture: drainage texture
is denoted by Rt and represents the total number of stream segments of all
orders per perimeter of the area (Horton, 1945). Drainage density is classified
into five classes i.e. very coarse ( 8) (Smith 1950).Form Factor: Form factor is the  ratio 
of  the  basin 
area  to  the 
square  of  basin 
length.  It is a dimensionless
property and is used as a quantitative expression of the shape of basin form.
The value of form factor would always be less than 0.7854 which perfectly
represents a circular basin and suggests lower peak flows of longer duration.
On the other hand smaller values of form factor represents elongated basin and
basin will have a flatter peak flow for longer duration.  Flood flows of elongated basin are easier to
manage than from the circular basin (Rajora, 1998; Panhalkar S. S. et al 2012,
Akram Javed et al., 2009; Nongkynrih
and Husain, 2011).   Circularity Ratio: Circularity ratio (Rc) is the ratio of
the area of a basin to the area of a circle having the same circumference as
the perimeter of the basin (Miller, 1953). Length and frequency of streams,
geological structures, land use/ land cover, climate and slope of the basin
these are the affecting factors of the circularity ratio. Circularity
ratios range from 0.4 to 0.5 which indicates strongly elongated and permeable
homogenous geologic materials. Higher values represents to the circular shape of the basin whereas
lower values represent elongated shape of the basin (Akram Javed et al., 2009; Nongkynrih and Husain, 2011).Elongation Ratio: Elongation ratio (Re) is the
ratio between the diameter of the circle of the same area as the drainage basin
and the maximum length of the basin. It is a very significant index in the analysis
of the basin shape which helps to give idea about the hydrological character of
a drainage basin (Nongkynrih and Husain, 2011, Panhalkar S. S. et al 2012). The values of elongation ratio generally vary from 0.6 to 1.0
and it can be change due to climate and geology. These values can be
categorized into three groups, i.e. circular (> 0.9), oval (0.9-0.8) and
less elongated (