geo-analyst , issn 2249-2909 2014gswb.in/wp-content/uploads/2014/08/subhajit.pdf · geo-analyst ,...

Geo-Analyst , ISSN 2249-2909 2014

27

THE RELATIONSHIP BETWEEN SOME OF CHANNEL GEOMETRIC

PARAMETERS AND CONSEQUENT SINUOSITY RATIO - A CASE STUDY

OF LOWER DUDUYA RIVER COURSE

Subhajit Chakraborty*

ABSTRACT

Duduya or Dudhuya is one of the main tributary rivers of Jaldhaka. In lower Duduya

river course, some channel geometric properties i.e. Channel length ( C L ) , Valley

length ( V L ) , Meander wavelength ( M L ) , Radius of curvature ( r m ) , Meander

amplitude ( A ) & Sinuosity ratio ( S I ) , are calculated with the help of satellite map

(Google Earth & measuring tools ) , Cadastral map ( scale – 16 inch to 1 mile ) &

field observations . For this purpose , the lower Duduya river course is divided

into five ( 5 ) segments ( A- B , B- C , C- D , D- E , E- F ) and calculated these

properties. As a result , it is seen that some of these properties are perfect positive

degree to no degree of correlation with each other and with sinuosity ratio . The

present study has exhibited how these parameters can change sinuosity ratio of

selected segments and their interrelationships. It was found that meander amplitude (A)

has maximum effort to increase sinuosity ratio in the lower part of Duduya

river.

KEYWORDS

Meander wavelength , Meander amplitude , Sinuosity ratio , Channel length , Valley length,

Radius of curvature .

INTRODUCTION

River is more or less straight for a certain distance , but no river can ever flow straight

path . The wavy river channel is clearly viewed in satellite map and aerial photographs .

Meandering is formed where banks resist erosion, so forming deep & narrow

channels. But till now , why rivers appear as meander is not clearly understood . But

few ideas are developed behind the formation of meander like (1) the distribution &

dissipation of energy within a river ( 2 ) helical flow & ( 3 ) the interplay of bank

erosion .

*Assistant Teacher in Geography, Jurapani High School , Jalpaiguri, West Bengal

CHANNEL GEOMETRIC PARAMETERS

Channel geometric parameters includes meander wavelength , meander amplitude , radius

of curvature , channel length , valley length , sinuosity ratio etc . and their

interrelationships ( Singh , 1998 ) .

Fig 2, Some of chan

Meander Wavelength (M L)

It is the axial length of one meander i.e. the tangential distance between

the corresponding points of a meander.

Meander Amplitude (A) It is the maximum distance from the down valley axis to the sinuous axis of

a meander loop.

Radius of Curvature ( r m )

It is the radius of a circle drawn through the apex of meander bend and two

crossover midpoints.

Channel Length (C L)

It is the representative curvilinear distance measurement along the centre of the channel

valley length.

Valley Length (V L) It represents representative horizontal distance measurement in the thalwag of two cross

sections in a linear depression between adjacent uplands .

Sinuosity Ratio ( S I ) It refers to departure of actual channel course (C L) from the expected theo

straight line (V L), (Schumm, 1963).

Geo-Analyst , ISSN 2249-2909

28

CHANNEL GEOMETRIC PARAMETERS

geometric parameters includes meander wavelength , meander amplitude , radius


interrelationships ( Singh , 1998 ) .

Fig 2, Some of channel geometric parameters


the corresponding points of a meander.

It is the maximum distance from the down valley axis to the sinuous axis of

a meander loop.

( r m )


crossover midpoints.

curvilinear distance measurement along the centre of the channel

valley length.

It represents representative horizontal distance measurement in the thalwag of two cross


It refers to departure of actual channel course (C L) from the expected theoretical

, 1963).

2014

geometric parameters includes meander wavelength , meander amplitude , radius



It is the maximum distance from the down valley axis to the sinuous axis of


curvilinear distance measurement along the centre of the channel

It represents representative horizontal distance measurement in the thalwag of two cross


retical

OBJECTIVES

( 1 ) To find out meander wavelength , amplitude , & radius of curvature for selected

segments . ( 2 ) To measure channel length & valley length and calculate sinuosity

ratio for each segment . ( 3 ) To compare sinuosity ratio for each section . (4) To

examine correlation between different parameters.

STUDY AREA

Jaldhaka river , is one of the major natural water channels in Duars region ,

Bengal which is formed by several small rivers originating from eastern Himalayan tract .

River Duduya is one of these small rivers.

Fig 3 :- Selected segments of lower Duduya course .

Duduya is originated from Binnaguri region , Jalpaiguri The total length of this river is

almost 53 km . After nourished by Kullaya ( 8 km ) , Angrabhasha ( 8 km ) , Echa ( 7

km ) , Goberghuta ( 10 km ) , Gartoli ( 15 k

has joined to the Jhaldhaka river near Indrerkuthi , Daribas phulbari , Coochbehar

district. The study area lies between the river bridge of NH

mouth of this river . Geographically, the region is located between 26.47° N to

26.54° N latitude and 89.10° E to 89.16° E longitude. It covers an area of 35.18 sq.

km.


29



ent . ( 3 ) To compare sinuosity ratio for each section . (4) To

examine correlation between different parameters.

Jaldhaka river , is one of the major natural water channels in Duars region ,


River Duduya is one of these small rivers.

Selected segments of lower Duduya course .



km ) , Goberghuta ( 10 km ) , Gartoli ( 15 km ) , Nosai ( 23 km ) etc torrents , this river


district. The study area lies between the river bridge of NH – 31 D ( Jurapani ) and



2014



ent . ( 3 ) To compare sinuosity ratio for each section . (4) To

Jaldhaka river , is one of the major natural water channels in Duars region , West




m ) , Nosai ( 23 km ) etc torrents , this river


Jurapani ) and



A B

Fig 4 :

DATA COLLECTION & METHODOLOGY

The information about the study

Google Earth & measuring tools ) , cadastral map ( Revenue survey , Jalpaiguri , scale

to 1 mile ) and field observations . Materials used were tracing paper ,

table & rotameter . Rotameter used for measure the channel length , valley length ,

meander wavelength ,amplitude & radius of curvature . The following formula is used for

calculating the sinuosity ratio.

Sinuosity ratio = Channel length ÷ Valley length ( Schumm , 1963 ) .

The scatter plot is used for showing correlation between

RESULTS & DISCUSSION

The analysis of table 1 shows that sinuosity ratio varies for each segment which

indicates differential channel pattern for different sections.

detecting in D – E segment, and E

C & C – D segments are indicating sinuous channel pattern. Overall ( A

sinuosity ratio ( 1.36 ) indicates sin

..

Table no. 1, Measurement of Sinuosity ratio

SELECTED

SEGMENTS

CHANNEL

LENGTH IN

METRE ( C L )

A TO B

B TO C

C TO D

D TO E

E TO F

Over All (A TO F) 10666.66

Source: Computed by Researcher


30

C D

Fig 4 :- Photos of study area ( A, B, C, D ) .

DATA COLLECTION & METHODOLOGY

The information about the study area was collected from the satellite map & images (

Google Earth & measuring tools ) , cadastral map ( Revenue survey , Jalpaiguri , scale

to 1 mile ) and field observations . Materials used were tracing paper , drawing pens , light



calculating the sinuosity ratio.

Sinuosity ratio = Channel length ÷ Valley length ( Schumm , 1963 ) .

The scatter plot is used for showing correlation between different parameters.


indicates differential channel pattern for different sections. Meandering channel pattern

E segment, and E – F segment are almost identical. Otherwise, A –

D segments are indicating sinuous channel pattern. Overall ( A

sinuosity ratio ( 1.36 ) indicates sinuous channel pattern ( Leopold and Wolman , 1957 )

Table no. 1, Measurement of Sinuosity ratio for each selected segments

CHANNEL

LENGTH IN

METRE ( C L )

VALLEY LENGTH

IN METRE ( V L )

SINUOSITY

RATIO

( S I )

1666.66 1233.33 1.35

1219.99 1166.66 1.05

2333.33 2150.00 1.08

3166.66 1833.33 1.73

2110.00 1466.66 1.44

10666.66 7833.33 1.36


2014

area was collected from the satellite map & images (

Google Earth & measuring tools ) , cadastral map ( Revenue survey , Jalpaiguri , scale - 16˝

drawing pens , light




nel pattern

– B, B –

D segments are indicating sinuous channel pattern. Overall ( A – F )

Leopold and Wolman , 1957 )

SINUOSITY

RATIO

( S I )

1.35

1.05

1.08

1.73

1.44

1.36

Meander wavelength , amplitude , radius of curvature & sinuosity ratio are tabulated in

Table no. 2 :- Measurement of meander wavelength , amplitude , radius of

SELECTED

SEGMENTS

MEANDER

WAVELENGTH

IN METRE

A - B 1200.00

B - C 1300.00

C - D 2200.00

D - E 1816.66

E - F 1433.33


meander wavelength and radius of curvature are increasing with each other for each

segment , according to emperical relation proposed by Leopold & Wolman ( M L =

4.7 r m 0.98

, 1960 ) except D

increase of amplitude, sinuosity ratio has increased but with t

wavelength , sinuosity ratio has not increased , instead it has decreased at several

segments .

RELATIONSHIPS AMONG CHANNEL GEOMETRIC PARAMETERS


31


table no - 2 .

Measurement of meander wavelength , amplitude , radius of

curvature & sinuosity ratio .

MEANDER

WAVELENGTH

IN METRE

MEANDER

AMPLITUDE

IN METRE

RADIUS OF

CURVATURE

IN METRE

SINUOSITY

RATIO

1200.00 733.00 253.33 1.35

1300.00 300.00 276.66 1.05

2200.00 633.33 473.33 1.08

1816.66 1400.00 333.33 1.73

1433.33 933.33 303.33 1.44


The analysis of table no . 2 shows that


erical relation proposed by Leopold & Wolman ( M L =

, 1960 ) except D – E segment ( where , M L = 5.45 r m 0.98

) . With the

increase of amplitude, sinuosity ratio has increased but with the increase of meander


segments .


2014


Measurement of meander wavelength , amplitude , radius of

SINUOSITY

RATIO

1.35

1.05

1.08

1.73

1.44

The analysis of table no . 2 shows that


erical relation proposed by Leopold & Wolman ( M L =

) . With the

he increase of meander




32

2014


33

2014

Fig 5 (A - F) :- Correlation between different geometric parameters by

The analysis shows that interrelationship of different channel geometric parameters have

yielded perfect positive degree to no degree of correlation ( fig

amplitude is moderate positively correlated with channel length & sinuosity ratio ( fig :

5A & 5B ) and weak positively correlated with meander wavelength ( fig

correlation with radius of curvature ( fig

between meander wavelength and sinuosity ratio ( fig

positive degree of correlation between radius of curvature & meander wavelength (

fig – 5 F ) . Weak negative relationship has been identified between radius of curvature and

sinuosity ratio ( fig – 5 G ) and perfect positive correlation has been identified

between meander wavelength and valley length ( fig

of relationship is detected between channel


34

Correlation between different geometric parameters by

using Scatter Plot .


yielded perfect positive degree to no degree of correlation ( fig – 5 ) . Meander

ositively correlated with channel length & sinuosity ratio ( fig :

5A & 5B ) and weak positively correlated with meander wavelength ( fig – 5 C ) but no

correlation with radius of curvature ( fig – 5 D ) . Almost no correlation is also found

between meander wavelength and sinuosity ratio ( fig – 5 E ) . There is also moderate


negative relationship has been identified between radius of curvature and

5 G ) and perfect positive correlation has been identified

between meander wavelength and valley length ( fig – 5 H ) . Moderate positive degree

between channel length & sinuosity ratio ( fig – 5 I ) .

2014

Correlation between different geometric parameters by


5 ) . Meander

ositively correlated with channel length & sinuosity ratio ( fig :-

5 C ) but no

orrelation is also found

5 E ) . There is also moderate


negative relationship has been identified between radius of curvature and

5 G ) and perfect positive correlation has been identified

H ) . Moderate positive degree

5 I ) .

Geo-Analyst , ISSN 2249-2909 2014

35

CONCLUSION

It may be concluded that meander wavelength is increasing with increasing radius of

curvature and closely related to each other . But these two geometric parameters

cannot play vital role for changing sinuosity ratio in different selected sections . On the

other hand, channel length and meander amplitude are increasing with each other

and influence the sinuosity ratio . Increase of channel length and meander

amplitude are the result of topographic factors and frequent flooding due to heavy

rainfall in hill region . Finally, it may be concluded that meander amplitude ( A )

has played major role in increasing sinuosity ratio in selected segments in lower

Duduya river course .

ACKNOWLEDGEMENT

I express my thanks to Mr. Bimal ch. Roy for assisting in field observations.

BIBLIOGRAPHY

Bhagabati, A, B & Bhattacharya, P. (2010). Doctoral Research in Geography – A Survey EBH

Publication. Guwahati.

Charlton R (2008). Fundamentals of fluvial geomorphology. Routledge, London & NY

Garde, R.J (2006). River morphology. New age international Ltd. Publication.

Leopold, L.B & Wolman, M. G. & Miller, J. P. (1964). Fluvial processes in

geomorphology. Dover Pub Inc. NY

Singh, S (1998). Geomorphology. Prayag Pustak Bhawan. Allahabad. India.

Tamrakar, N. K & Shrestha, P. (2012). Morphology & Classification of the main stem

Bagmati river, Central Nepal. Bulletein of the Dept. of Geology , Tribhuvan University ,

Nepal.

Uddin. M, Deb. M & Das D (2012). Remote sensing based analysis of critical bends of

Kushiyara River in Bangladesh. Geographia technica , no – 2 , pp . 84 – 94.

Yeasmin. A & Islam, N. M (2011). Changing trends of channel pattern of the Ganges -

Padma River”. International journal of Geomatics & Geosciences, Vol. 2, no – 2.

geo-analyst , issn 2249-2909 2014gswb.in/wp-content/uploads/2014/08/subhajit.pdf · geo-analyst ,...

Documents