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.

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 (< 2), coarse (2-4), moderate (4-6), fine
(6-8) and very fine (> 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 (<0.7) (Akram
Javed et al., 2009). High Re values =high infiltration capacity and low runoff
(Sreedevi, Owais et. Al 2009) Relief
Properties:
Average Slope: Slope is defined as the angular
inclination of terrain between hill-tops and valley bottoms. Slope angle in
degree of the drainage basin are tabulated and classified into convenient slope
categories viz., (i) level slope = 00–100, (ii) gentle
slope = 100–220, (iii) moderate slope = 220–
300, (v) steep slope = 330 – 430, and (vi)
very steep slope = above 430. The average slope is used in watershed
development analysis for find out the site suitability of storage of water,
like as dam. The storage of water, soil erosion on hill slopes can be estimate
by using the average slope data (Nongkynrih and Husain, 2011).Basin
relief (H): It is the maximum vertical distance
between the lowest and highest points of watershed. It is also known as total
relief. (Chaudhari et al. 2014).Relief
Ratio: It is the
indicator of steepness of drainage basin and used as indicator of the intensity
of erosion processes operating on the slope of the respective basin. It's
simply the ratio of maximum relief to horizontal distance along the longest
dimension of the basin parallel to the principle drainage line (Schumn, 1956).
The lowest value of relief ratio interprets as gentle slope of the drainage
basin and vice-versa (Akram Javed et al., 2009; Nikam et al., 2014)Relative Relief: Relative relief termed as
'amplitude of available relief' or 'local relief' is defined as the difference
in height between the highest and the lowest points (height) in a unit area. It
is an important morphometric variable used for the overall assessment of
morphological characteristics of terrain.Ruggedness Number (R): It is combined
measure of relief and stream density. Complication of topography and ruggedness
number is proportionally related to each other. When topography become complex
the ruggedness number increases. To calculate R, multiply the drainage density
(D) by basin relief (H). R = DH. The relative peak discharge ratio increases
with the increase in ruggedness number (Muthukrishnan et al.,2013)Discussion and Conclusion:
The
morphometric analysis works is a powerful tool in river basin management. It
plays significant role in planning, watershed prioritization, soil and water
conservation, and management of natural resources at different levels. It is
also useful to understand rock structure, infiltration rate, runoff and erosion
of the soil in the watershed (Chaudhari et al. 2014). Watershed prioritization
could not be possible without study of morphometric analysis of watershed.