Analysis of drainage morphometry and watershed ... · Map, Slope Map have been prepared. ... Figure 3: Drainage water and surface water body map ... hill area. Coarse loamy soil is

INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES

Volume 2, No 4, 2012

© Copyright 2010 All rights reserved Integrated Publishing services

Research article ISSN 0976 – 4380

Submitted on March 2012 published on May 2012 995

Analysis of drainage morphometry and watershed prioritization in Bandu

Watershed, Purulia, West Bengal through Remote Sensing and GIS

technology - A case study

Ajoy Das1, Milan Mondal

2, Bhaskar Das

3, Asim Ratan Ghosh

4

1- Junior Research Fellow, West Bengal State Council of Science and Technology (DST),

Govt. of West Bengal

2- Senior Research Fellow, The University of Burdwan, Burdwan-713104

3- Senior Research Fellow, West Bengal State Council of Science and Technology (DST),

Govt. of West Bengal

4- Senior Scientist, West Bengal State Council of Science and Technology (DST),Govt. of

West Bengal

[email protected]

ABSTRACT

The study area, Bandu watershed of Purulia District extends from 23o 20’ N to 23

o 47’ N’ and

86o 0’ E to 86

o 30’ E. The study area is under the upper catchment of Kasai river, Purulia

district is a drought prone district of the West Bengal. Inspite of considerable amount of

rainfall, due to heavy runoff the main problem of this area is scarcity of water as well as soil

erosion. It has been accepted that for sustainable rural livelihood water and soil conservation

is a must. The most suitable way to achieve this is micro-watershed development. But there is

an acute shortage of technical manpower to handle such a huge volume of survey related

work. For that reason, application of Remote Sensing and GIS has become a necessity.

Moreover since fund is limited, watershed prioritization is highly required.

Key words: Watershed prioritization, Morphometric analysis, Micro-watershed, RS, GIS

1. Introduction

In the present study various thematic maps viz. Geomorphological Map, Drainage, Watershed

and Surface Waterbody Map, Landuse/ landcover Map, Transport and Settlement Map, Soil

Map, Slope Map have been prepared. These maps have been used for prioritization of mini-

watersheds through morphometric analysis, generally the criteria for watershed prioritization

are subjective in nature and difficult to implement in ground reality due to various reasons.

Some objective criteria are also available for watershed prioritization viz. Sediment Yield

Index. In the present study another objective approach has been attempted which is based on

morphometric analysis of drainage system and shape-size of their micro-watersheds.

The study area, Bandu watershed (geographical area: 648.24 sq.km) is lying between

23o20'00"N to 23

o47'00"N and 86

o0'00"E to 86

o30'00"E, Jhalda-II, Arsha and Baghmundi and

Jaipur block of Purulia district. Purulia district is a drought prone district of West Bengal.

The main problem of this area is scarcity of water as well as soil erosion (Figure 1).

1.1 Geomorphology

The Puruliya district of West Bengal presents a thoroughly pene-planated surface. The study

area is composed of slightly elevated nearly level to moderately sloping tracts of uplands and

Analysis of drainage Morphometry and Watershed prioritization in Bandu Watershed, Purulia, West Bengal

through Remote Sensing and GIS technology - A case study

Ajoy Das et al.,

International Journal of Geomatics and Geosciences

Volume 2 Issue 4, 2012 996

shallow valleys alternating in space throughout the area. In the western part of the study area

structural highlands that is Ajodhya hills (above 600 mts.) and part of the Baghmundi hills as

well as some residual hills (inselbergs) are found.

Figure 1: Location of the study area (Bandu watershed, Purulia, W.B)

These highlands and residual hills are a testimony to the high plateau of ancient times which

has been eroded down to produce the present landform. It can be said that in some sectors soil

erosion to be almost completed. It is evident from the occurrence of erosion pavement at the

surface. Some gully erosion has been taken place in the south-central part of the study area

which comprises with foothill zone. Along the upper Kasai (Left Bank and few parts of right

Bank) and Bandu River banks badland topography is found. The residual material on the



Ajoy Das et al.,



slopes has undergone deep weathering at places giving rise to deep “in-situ” soils. Local

alluvium deposits are also found in rest of the region due to low relief condition (IMSD,

1996) (Figure 2).

Figure 2: Geomorphological map

1.2 Drainage

All the rivers of the study area flowing within it have south or south-east to north-easterly

courses for Bandu river and in the upper reaches of Kasai river north-west to easterly courses

seen. The Kasai has its origin in the Jhalda-II block of Puruliya district. It is the most

important river of the region draining more than 50 percent of the region. The Bandu is the

another important river of this watershed which takes its origin in the Baghmundi block of

Puruliya district. The important rivers are Puran Baruadih nala and Chunmatia nala. All these

rivers are non-perennial and subject to flash floods. The most striking feature of surface

drainage in the area is the presence of several dug out ponds and some water harvesting

structures locally called bunds. These structures are suitable for considerable amount of water

conservation. These structures provide life saving irrigation to crops and helps in ground

water recharge. The croplands located below the water harvesting structures are most suitable

for paddy cultivation and the area is known as Bahal fields. Numerous small irrigation

reservoirs and tanks are also found in the area (Figure 3).

1.3 Climate

The climate of the region is characterised by a hot summer and well distributed seasonal

rainfall. The year may be divided into the following four seasons. The average rainfall of

Puruliya district is 1353.4 mm. South-western monsoon is responsible for the occurrence of

rainfall. During June to September near about 80% annual rainfall occurs. The month of

August witnesses highest rainfall. May is the hottest month with a mean daily maximum

temperature of 40.30o C and a mean daily temperature of 27.20

o C. January is the coldest

month of the region. Annual and diurnal range of temperature is quite high in this district.



Ajoy Das et al.,



1.4 Soil

The soils of the area under study are residual soils developed “in-situ” mostly from granitic

rocks. They are mostly loamy sand to sandy loam at the surface with a heavier sub-soil

showing evidence of clay illuviation at places, coloured various shades of red and are low in

inherent fertility (Figure 4).

Figure 3: Drainage water and surface water body map

As the region is a part of eastern fringe of Chhotonagpur plateau the soil is predominantly

loamy which is not very fertile. The soil of the study area can be classified into four broad

categories namely Fine Loamy, Coarse Loamy, Loamy skeletal and Fine. Fine loamy soil is

deep, brown sandy clay loam surface and clay loam sub-surface, imperfectly drained on

gently sloping infilled valley having high water table. This type of soil is found in Ayodhya

hill area. Coarse loamy soil is characterized by moderately deep, reddish brown sandy loam

surface to sandy clay loam sub-surface (gritty), well drained on moderately sloping lower

slopes of upper undulating plain (buried pediment).Loamy skeletal soil is characterized by



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shallow, brown to reddish brown, gravelly sandy loam surface to sandy clay loam sub-surface,

well drained on moderately sloping upper pediment, stones and gravel on surface.Gravel

loamy soil is found in some form of patches in the eastern part of the region (Figure 5).

Figure 4: Soil texture map

Figure 5: Landuse/ Landcover map



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2. Objectives

The main objectives of this study are (i) prioritization of mini-watersheds through

morphometric analysis generation of relevant thematic maps for the aforesaid studies. It has

been accepted that for sustainable rural livelihood water and soil conservation is a must. The

most suitable way to achieve this is micro-watershed development. Since fund is limited,

watershed prioritization is highly required. Common Guidelines for Watershed Development

has identified some criteria for this purpose. Some of them are (a) not more than 30% of the

area should get assured irrigation, (b) acute drinking water crisis, (c) high SC/ST population,

Some objective criteria are also available for watershed prioritization viz. Sediment Yield

Index (SYI). In the present study another objective approach has been attempted which is

based on morphometric analysis of drainage system and shape-size of their micro-watersheds.

3. Methods

Remote sensing technique with visual interpretation approach was adopted for generation of

various thematic maps.

Figure 6: Flow chart showing methodology of thematic map generation

It involves interpretation of imagery by using image elements and correlating them with land

features such as lithology, landforms, vegetation cover, soil and drainage. To prepare

thematic map first of all base map has been generated. A base map is a map shows only

essential geographic references (such as rail, road, main drainage (double line) on which



Ajoy Das et al.,



additional information is plotted; e.g., a topographic map on which geologic information is

recorded. A map designed for the presentation and analysis of data; it usually includes only

the coordinate, geographical and major political outlines. To prepare base map identify

permanent features from georeferenced FCC images and rectify all features from SOI

toposheet with scale of 1:50000.After rectification digitization of permanent features

(metalled road, rail line, canal, political boundaries and forest boundary) has been done. Main

drainage (double line) also has been digitized. Then central point of major settlement has

been pointed out.

To generate various theme maps of study area information has been extracted from three

seasons ( Kharif, Rabi, Zaid ) satellite images taken by IRS-P6, LISS-III and LISS-IV of

2006. These Satellite imageries had been georeferenced and merged using image processing

software ERDAS IMAGINE 8.4. These remotely sensed data were geometrically rectified

with respect to survey of India toposheets on 1:50,000 scale. These merged data were used in

the present study. Image enhancement techniques were applied for better interpretation of the

study area. In the beginning a personal geodatabase has been created to generate feature class.

With the help of these feature classes different themes have been digitized on screen. In this

way different layers like geology, geomorphology, drainage, soil, landuse/ landcover,

transport and settlement have been generated for corresponding theme maps. To compare and

interpret all these theme maps overlay analysis has been done. The entire procedure of theme

map generation from georeferenced data have been done in ArcGIS 9.3 environment. After

completion of map generation field verification or ground truth survey has been done for area

estimation. After that final theme maps have been prepared of the present study (Figure 6).

4. Fluvial Morphometry

Fluvial morphometry is the measurement and mathematical analysis of configuration of earth

surface and of the dimension of its landforms originated due to fluvial processes. The

morphometric analysis is carried out through measurement of linear, aerial and relief aspects

of the basin and slope contribution (Nag and Chakraborty, 2003) to understand the run-off

characteristics of the area and potentiality of watershed deterioration. The measurement of

various morphometric parameters namely – stream order, stream length (Lu), mean stream

length, bifurcation ratio, mean bifurcation ratio, drainage density, stream frequency, form

factor, circulatory ratio, elongation ratio, length of overland flow has been carried out and the

data are presented in the following table. In the present study, the satellite remote sensing

data has been used for updation of drainage network, obtained from SOI toposheets and the

updated drainage network has been used for morphometric analysis.

4.1 Linear aspects

Fluvial morphometry include the consideration of linear, aerial and relief aspect of fluvially

developed drainage basin. The linear aspects include the stream order, stream length, mean

stream length, stream length ratio and bifurcation ratio, which were determined and results

have been presented in the following Table 3.

4.1.1. Stream ordering

Stream ordering is a method of assigning a numeric order to links in a stream network. This

order is a method for identifying and classifying types of streams based upon their number of

tributaries. Some characteristics of streams can be inferred by simply knowing their order.



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The designated stream order is the first step in the drainage basin analysis. In the present

study, ranking of streams has been carried out based on the method proposed by Strahler

(1964). It is noticed from the table that the maximum frequency is in the case of first order

streams. It is also observed that there is a decrease in stream frequency as the stream order

increases.

4.1.2. Stream length

Stream length is measured from mouth of a river to drainage divide.

4.1.3. Mean stream length

Mean Stream Length of a stream channel system is a dimension less property revealing the

characteristics of size of a component of drainage network and its contributing basin set.

Lu= ∑Lu/Nu

Where, ∑Lu= Total length of a order

Nu= No of stream of that order.

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 the

order.

4.1.4. Stream length ratio

Stream length ratio (RL) is the ratio of the mean length of the one order to the next lower

order of the stream segments.

4.1.5. Bifurcation ratio

According to Schumn (1956), the term bifurcation ratio may be defined as the ratio of the

number of the stream segments of given order to the number of segments of the next higher

orders. Bifurcation ratio shows a small range of variation for different regions or for different

environments except where the powerful geological control dominates (Strahler, 1957).

Bifurcation Ratio (Rb): Gregory

Bifurcation ratio is defined as the ratio of the number of stream of a given order to the

number of stream to the next higher order which is expressed in terms of following equation-

Rb = Nu/ Nu+1

Where, Rb = Bifurcation Ratio.

Nu= Number of segments of a given order segment.

Nu+1=Number of segments of the next higher order.

It varies from 2 to 5. Rb is used to find out the degree of integration in drainage basin. Rb

depends on the slope, physiography, and climate. Aerial aspects include different

morphometric parameters, like drainage density, texture ratio, stream frequency, form factor,



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circularity ratio, elongation ratio and length of the overland flow. The values of these

parameters are presented in the table and discussed and interpreted.

4.1.6. Drainage density

Drainage density is defined as the total length of streams of all orders per drainage area.

Density factor is related to climate, type of rocks, relief, infiltration capacity, vegetation

cover, surface roughness has no significant correlation with drainage density. The drainage

density indicates the closeness of spacing of channels (Horton, 1932). It may be considered as

one of the methods of measurement of basin area.

According to Horton, Drainage Density is defined ratio of total length of all stream segments

in a given drainage basin to the total area of that basin. It is expressed by a formula

DD = ∑L/A

Where, ∑L = Total length

A = Total area

The amount and type of precipitation influences directly to the quantity and characters of

surface run-off. An area with high precipitation such as thundershowers loses greater

percentage of rainfall in run-off resulting in more surface drainage lines. Amount of

vegetation and rainfall absorption capacity of soils, which influences the rate of surface run-

off, affects the drainage texture of an area. The similar condition of lithology and geologic

structures, semi-arid regions have finer drainage density texture than humid regions. Low

drainage density generally results in the areas of highly resistant or permeable sub-soil

material, sparse vegetation and mountainous relief. Low drainage density leads to coarse

drainage texture while drainage density leads to fine drainage texture.

4.1.7. Stream frequency/channel frequency

The total number of stream segments of all orders per unit area is known as stream frequency

(Horton, 1932). Hopefully, it is possible to have basins of same drainage density differing

stream frequency and basins of the same stream frequency differing in drainage density.

Stream Frequency is defined as the ratio between the number of stream segment per unit area

which expressed by a formula

DF= ∑N/A where, ∑N= Total no of stream segment; A= Unit area in km2 or m2

It is a technique which is also used in planning and development to identify land quality for

optimum utilization.

4.1.8. Drainage texture

Drainage texture is the total number of stream segments of all orders per perimeter of that

area (Horton, 1945). It is one of the important concepts of geomorphology which means that

the relative spacing of drainage lines. Drainage lines are numerous over impermeable areas

than permeable areas. According to Horton (1945), infiltration capacity as the single

important factors which influences drainage texture and considered drainage texture which

includes drainage density and stream frequency.



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4.2 Areal Aspects

4.2.1. Form factor

Form factor may be defined as the ratio of the area of the basin and square of basin length

(Horton, 1932). The value of form factor would always be greater than 0.78 for a perfectly

circular basin. Smaller the value of form factor, more elongated will be the basin.

4.2.2. Circularity ratio

The circularity ratio is mainly concentrated with the length and frequency of streams,

geological structures, land use/land cover, climate, relief and slope of the basin. It is the ratio

of the area of the basins to the area of circle having the same circumstance as the perimeter of

the basin.

4.2.3. Elongation ratio

Elongation ratio is the ratio between the diameter of the circle of the same area as the

drainage basin and the maximum length of the basin.

4.2.4. Compactness constant

Compactness ratio is defined as the ratio between the area of the basin and the perimeter of

the basin.

Table 1: Formula adopted for computation of morphometric parameters

Sl

No.

Morphometric

Parameters

Formula Reference

1 Stream Order Hierarchical rank Strahler

(1964)

2 Stream Length (Lu) Length of the Stream Horton

(1945)

3 Mean Stream Length

(Lsm)

Lsm=Lu/Nu

Where, Lu=Total stream length of order ‘u’

Nu=Total number of stream segments of order

‘u’

Strahler

(1964)

4 Stream Length Ratio

(RL)

RL=Lu/lu-1

Where, Lu= Total stream length of order ‘u’

Lu-1= Total stream length of its next lower

order

Horton

(1945)

5 Bifurcation Ratio (Rb) Rb=Nu/Nu+1

Where, Nu=Total number of stream segments

of order ‘u’

Nu+1= Total stream length of its next higher

order

Schumn

(1956)

6 Mean Bifurcation Ratio

(Rbm)

Rbm=Average of bifurcation ratios of all

orders

Strahler

(1957)

7 Drainage Density (D) D=Lu/A

Where, Lu= Total stream length of all orders

A=Area of the basin(km2)

Schumn

(1956)



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8 Basin Length (Lb) Lb=1.312*A0.568

Where, Lb=Length of the basin(km)


Horton

(1932)

9 Stream Frequency (Fs) Fs=Nu/A


of all orders


Horton

(1932)

10 Texture Ratio (Rt) Rt=Nu/P


of all orders

P=Perimeter of the basin(km)

Horton

(1945)

11 Form Factor (Rf) Rf=A/Lb2)

Where, A=Area of the basin(km2)

Lb2 =Sq of basin length

Horton

(1932)

12 Circularity Ratio (Rc) Rc=4*Pi*A/P2

Where, Pi=’Pi’ value i.e.,3.14


P2 = Sq of the perimeter(km)

Miller

(1953)

13 Elongation Ratio (Re) Re=(2/Lb)*(A/Pi)0.5

Where, Lb=Basin length(km) ,A=Area of the

basin(km2)

Schumn

(1956)

14 Compactness Ratio

(Cc)

Cc=0.2821*P/A2

Where, P=Perimeter of the basin(km)


Horton

(1945)

Source: Thakkar, A. K. and.Dhiman, S.D (2007)

Table 2: Morphometric Parameters of Bandu watershed

Sl.

No.

Min

i-

Wa

ters

hed

Cir

cula

r

Ra

tio

Bif

urc

ati

on

Ra

tio

Fo

rm

Fa

cto

r

Elo

nga

tio

n

Ra

tio

Co

mp

act

ne

ss C

on

sta

nt

Str

eam

Fre

qu

ency

Dra

ina

ge

Den

sity

Tex

ture

Ra

tio

1 2A2B5C4 0.47 2.88 0.057 0.269 1.462 6.44 3.13 6.40

2 2A2B5B7 0.49 1.62 0.055 0.264 1.426 6.80 3.24 8.02

3 2A2B5C3 0.48 1.88 0.057 0.270 1.439 3.59 2.54 3.48

4 2A2B5C7 0.48 2.48 0.055 0.266 1.437 2.69 1.89 2.99

5 2A2B5C2 0.48 1.81 0.054 0.261 1.445 4.62 2.41 5.72

6 2A2B5C6 0.64 2.04 0.060 0.276 1.249 4.68 2.23 4.48

7 2A2B5C5 0.31 1.91 0.054 0.263 1.807 1.35 1.46 1.27

8 2A2B5C1 0.34 3.18 0.061 0.280 1.704 3.08 2.50 1.97

9 2A2B5A1 0.67 1.83 0.060 0.276 1.223 1.07 1.01 1.04

10 2A2B5B1 0.37 1.62 0.053 0.260 1.642 2.71 1.71 3.06

11 2A2B5B2 0.47 1.57 0.057 0.269 1.464 3.32 2.13 3.28

12 2A2B5B3 0.39 2.02 0.057 0.271 1.598 4.32 2.52 3.76

13 2A2B5A2 0.53 2.13 0.059 0.275 1.371 1.58 1.28 1.42

14 2A2B5B6 0.24 1.65 0.056 0.266 2.030 6.44 2.79 4.94

15 2A2B5B4 0.36 2.40 0.057 0.270 1.659 3.72 2.25 3.19

16 2A2B5B5 0.56 1.66 0.058 0.272 1.341 1.10 1.15 1.10

17 2A2B5A1

1 0.78 2.00 0.060 0.275 1.132 1.66 1.24 1.79

18 2A2B5A6 0.48 3.21 0.062 0.280 1.441 3.83 2.13 2.84

19 2A2B5A5 0.57 2.66 0.064 0.286 1.328 4.27 2.07 3.01



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20 2A2B5A3 0.46 4.13 0.057 0.270 1.467 1.43 1.11 1.36

21 2A2B5A4 0.66 1.67 0.056 0.267 1.231 3.98 2.14 4.90

22 2A2B5A7 0.52 1.49 0.062 0.280 1.387 4.49 2.06 3.50

23 2A2B5A8 0.72 1.59 0.061 0.279 1.179 3.35 1.79 3.16

24 2A2B5A9 0.41 2.21 0.061 0.279 1.557 2.80 1.75 2.01

25 2A2B5A1

0 0.36 1.77 0.054 0.263 1.675 2.36 1.72 2.44

Table 3: Suitable Sensor and their application in Watershed Management

Image number: 106/55

Acquired on:

21st January, 2006

3rd

April, 2006

Image number: 106/56

12th

October, 2006

Acquired on:

16th

January, 2006

29th

March, 2006

7th

October, 2006

To prepare theme maps satellite data of geocoded FCC of bands 2, 3, 4 on 1:50,000 scales

along with corresponding SOI toposheet no.73I/3,73I/4,73I/7 and 73I/8.

The generated theme maps are as follows:

(1) Geomorphological Map

(2) Drainage, Watershed and Surface Waterbody Map

(3) Landuse/ landcover Map

(4) Transport and Settlement Map

(5) Soil Map

6) Slope Map

(7) Map showing catchment area of selected check dam sites

4.3 Watershed Concept

Watershed is a technical term used by the British to denote a common drainage point. It is a

hydro geological unit. In American terminology, it is referred to as Catchment Area.

Watershed is the line separating neighboring drainage basins (catchments). In hilly country,

the divide lies along topographical peaks and ridges, but in flat country (especially where the

ground is marshy) the divide may be invisible – just a more or less notional line on the

ground on either side of which falling raindrops will start a journey to different rivers, and

even to different sides of a region or continent. Drainage divides are important geographical



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and often also political boundaries. Roads (such as ridge ways) and rail tracks often follow

divides to minimize grades (gradients), and to avoid marshes and rivers.

4.4 Causes of watershed deterioration

1. Uncontrolled, unplanned, unscientific land use and interventions lead to deterioration

of the watershed area. Some of the activities detrimental to watershed.

2. Cultivation on sloping land without adequate precautions, cultivation without

agronomic measures to conserve soil and water, cultivation along susceptible nalla

banks, cultivation of erosion-permitting crops, over-cropping without soil fertility

replenishment, faulty agricultural techniques etc.

3. Grass land: Excessive and uncontrolled grazing, growth of weeds, development of

cattle tracks causing damage and compaction of soil resulting in lower infiltration

rates, fires, theft etc.

4. Forest: Excessive and uncontrolled grazing which inhibits regeneration from seed or

stock, clear felling on steep slopes, destruction of forest land by fires and thefts, biotic

pressure for fuel, fodder, NTFP and small timber, drastic thinning of plantation along

slopes etc.

5. Shifting cultivation: Shifting cultivation or Jhum kheti practiced in certain areas of

counties (like North East India etc.) has proved to be very damaging to protective and

productive vegetation. This practice results in damage to the topsoil and inhibits the

growth of grasses, shrubs and trees.

6. Unscientific mining and construction activities: These activities damage the

vegetation and the landscape. The natural drainage lines are often blocked by debris.

7. Fire: Intentional / accidental fires result in loss of vegetation, organic matter and

micro-organisms.

8. Non-cooperation of the community: Non-Cooperation of the community in

conserving, protecting and enriching then ecosystem and CPR has also resulted in

most of the ills.

4.5 Why Watershed Management?

Watershed management is required for the following reasons:

1. To control damaging runoff.

2. To manage and utilize runoff for useful purposes.

3. To control erosion affecting reduction of sediment production.

4. To moderate floods in the downstream area.

5. To enhance groundwater storage wherever applicable, and

6. To appropriately use land resources in the watershed, thus developing forests and

fodder resources.

5. Methods



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To delineate micro-watersheds, prioritization of mini-watersheds through morphometric

analysis in Bandu watershed has been attempted through integrated use of remote sensing and

GIS techniques. In the present study, the drainage map of the study area has been prepared

from three season’s satellite images of IRS-P6 (Resourcesat) LISS-III and LISS-IV of 2006.

LISS-III (106/55) satellite data were acquired on 21st January, 3rd April, and 12th October of

2006 and LISS-III (106/56) 16th January, 29th March and 07th October of 2006.These

satellite imageries had been georeferenced and merged using image processing software

ERDAS IMAGINE 9.1. These remotely sensed data were geometrically rectified with respect

to survey of India toposheet with 1: 50,000 scale. These merged data were used in the present

study. Image enhancement techniques were applied for better interpretation of the study area.

To delineate drainage map satellite data of geocoded FCC of bands 2, 3, 4 on 1: 50,000 scales

along with corresponding toposheets have been used 73I/3, 73I/4, 73I/7, and 73I/8. The

morphometric parameters for the delineated watershed area were calculated based on formula

suggested by various authors viz. Horton, Strahler, Schumn and Miller, presented in Table.1.

Digitization and computation of output value were done in ArcGIS 9.3 environment. On the

basis of some selected morphometric parameters watershed prioritization of all micro-

watersheds was carried out (Figure 7).

Figure 7: Flow chart showing methodology of micro-watershed prioritization map

The step wise methodology is listed as below

1. Drainage has been digitized as separate segments for every stream order.

2. Delineation of subwatershed, mini-watershed and micro-watershed have been done.

3. Computation of number and length of streams of every order for every mini-

watershed area have been done.



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4. Computation of eight morphometric parameters namely Mean Bifurcation Ratio,

Drainage Density, Texture Ratio, Stream Frequency, Circularity Ratio, Form Factor,

Compactness Constant, Elongation Ratio have been made

5. Since higher value of Mean Bifurcation Ratio, Drainage Density, Texture Ratio,

Stream Frequency indicates higher potentiality of watershed deterioration these

parameters are given rank in descending order. Since lower value of Circularity Ratio,

Form Factor, Compactness Constant, Elongation Ratio indicates higher potentiality of

watershed deterioration these parameters are given rank in ascending order.

6. All parameters are assumed to have equal weights. The average rank for all mini-

watersheds are computed. Final rank has been assigned in ascending manner. (Table.

4)

5.1 Observation

On the basis of above mentioned observation it can be concluded that Remote Sensing and

GIS techniques are efficient tools in drainage delineation and their updation. These updated

drainages are treated as input data for morphometric analysis. This analysis was carried out

through measurement of linear, aerial and relief aspects of micro-watersheds. This

morphometric analysis reveals dendritic to sub-dendritic, parallel, radial drainage patterns

with moderate drainage textures of the entire sub-watershed. The variation in stream length

ratio reflects the change in slope and topography. The bifurcation ratio of sub-watersheds

indicates normal basin category and the area having moderate drainage density reflects that it

has highly permeable sub-soil and coarse to moderate drainage texture. The values of stream

frequency indicate that all the micro-watersheds show positive correlation with increasing

stream population with respect to increasing drainage density. The values of form factor and

circularity ratio evolve that almost all micro-watersheds are elongated in shape. Elongation

ratio indicates that Bandu watershed is a region of very low relief whereas other micro-

watersheds are characterized by moderate to high relief and steep ground slopes relief and

steep ground slopes.

5.2 Results and discussion

Stream length has been computed based on the law proposed by Horton (1945) for all the

micro watershed of the study area. Usually, the total length of stream segments is maximum

in first order streams and decreases as the stream order increases in the present case. The

mean stream length is presented in the table. The Bifurcation Ratio (Rb) values of study area

indicates that there is a uniform decrease in Rb values of 2A2B5A3 to 2A2B5A7, from one

order to the next order whereas in other micro watersheds, the Rb values are not same from

one order to next order. These differences are depending upon the geological and lithological

development of the drainage basin. In the study area, the higher values of Rb indicates a

strong structural control in the drainage pattern whereas the lower values indicate that the

sub-basins are less affected by structural disturbances (Nag, 1998; Vittala et al., 2004 and

Chopra et al., 2005). The Rb values of the micro watersheds of the study area range from

1.00 to 8.00 indicating that all the micro watersheds are falling under normal watershed

category

The drainage density in the micro watersheds of the study area shows variation from 1.47 to

4.20 per km2 suggesting moderate drainage density. This moderate drainage density of the

study area suggests that it has moderately permeable sub-soil and fine drainage texture



Ajoy Das et al.,



observed on hilly terrain. The Stream Frequency (Fs) values of the of the study area are

presented in the following table. It is noted that the values of Fs vary from 1.20 to 10.37. It is

also seen that the drainage density values of the micro watersheds exhibits positive

correlation with the stream frequency suggesting that there is an increase in stream

population with respect to increasing drainage density. The values of drainage texture ratio of

the study area vary from 1.04 to 8.02 . According to Smith (1950), five different drainage

textures have been classified based on the drainage density. The drainage density less than 2

indicates very coarse, between 4 and 6 is moderate, between 6 and 8 is fine and greater than

8 is very fine drainage texture. The 2A2Bb7 micro watershed has high values of Rt indicating

very fine drainage texture whereas the remaining micro watersheds show coarse to moderate

drainage texture exhibited by the surrounding source rock while the lower values may

indicate that the rocks exposed in the form of small ridges and mounds and plains with lower

degree of slopes.The form factor (Rf) values of the study area are presented in the Table. It is

noted that the Rf values vary from 0.053 to 0.064 micro watershed suggesting that it is almost

circular in shape. In the study area, the Circularity Ratio (Rc) values are ranging from 0.30 to

0.63. Those micro watersheds have the value of Rc is less than 0.5 indicating those are

elongated, whereas the remaining micro watersheds have greater than 0.5 values suggesting

that they are more or less circular in shape and are characterized by the high to moderate

relief and the drainage system were structurally controlled.The elongation ratio values of the

micro watersheds vary from 0.286 to 0.260. On the basis of elongation ratio it is also

suggested that the Bandu watershed is elongated in shape. A circular basin is more efficient

in the discharge of run-off than an elongated basin (Singh and Singh, 1997). In Bandu

watershed compactness ratio varies from 2.03 to 1.32.

Table 4: Prioritization Results of Morphometric analysis

Sl.

No.

Min

i- W

ate

rsh

ed

Cir

cula

rity

Ra

tio

Fo

rm F

act

or

Elo

nga

tio

n R

ati

o

Co

mp

act

-nes

s ra

tio

Str

eam

Fre

qu

ency

Dra

ina

ge

Den

sity

Tex

ture

Ra

tio

Bif

urc

ati

on

ra

tio

SU

M R

AN

K

Fin

al

Ra

nk

1 2A2B5C4 11 9 9 15 3 2 2 4 12.38 3

2 2A2B5B7 16 5 5 10 1 1 1 22 12.13 2

3 2A2B5C3 14 13 13 12 12 4 9 14 17.88 11

4 2A2B5C7 15 6 6 11 18 15 15 6 16.25 7

5 2A2B5C2 12 2 2 14 5 7 3 16 11.38 1

6 2A2B5C6 21 18 18 5 4 9 6 10 19.13 14

7 2A2B5C5 2 4 4 24 23 20 23 13 18.38 12

8 2A2B5C1 3 22 22 23 15 6 19 3 22.88 16

9 2A2B5A1 23 19 19 3 25 25 25 15 27.25 25

10 2A2B5B1 6 1 1 20 17 19 13 21 15.75 5

11 2A2B5B2 10 10 10 16 14 12 10 24 19 13

12 2A2B5B3 7 14 14 19 7 5 7 11 17.25 10

13 2A2B5A2 18 16 16 8 21 21 21 9 23.5 18

14 2A2B5B6 1 7 7 25 2 3 4 20 13.63 4

15 2A2B5B4 5 11 11 21 11 8 11 7 16.63 8



Ajoy Das et al.,



16 2A2B5B5 19 15 15 7 24 23 24 19 25.25 24

17 2A2B5A11 25 17 17 1 20 22 20 12 24.25 21

18 2A2B5A6 13 24 24 13 10 11 16 2 23.38 17

19 2A2B5A5 20 25 25 6 8 13 14 5 24 20

20 2A2B5A3 9 12 12 17 22 24 22 1 21.13 15

21 2A2B5A4 22 8 8 4 9 10 5 18 15.75 6

22 2A2B5A7 17 23 23 9 6 14 8 25 24.63 22

23 2A2B5A8 24 21 21 2 13 16 12 23 25 23

24 2A2B5A9 8 20 20 18 16 17 18 8 23.88 19

25 2A2B5A10 4 3 3 22 19 18 17 17 16.88 9

Figure 8: Map Showing Mini-Watersheds

Figure 9: Prioritisation Map – Mini Watersheds



Ajoy Das et al.,



5.3 Discussion about prioritization of mini-watersheds

On the basis of above mentioned 25 drainage morphometric parameters prioritization

procedure of Bandu watershed has been done at mini-watershed level (Figure 8 & 9). Since

the value of Bifurcation ratio is highest (4.13) in 2A2B5A4 mini-watershed possibility of

maximum erosion is maximum here. The highest drainage density is observed in

2A2B5B7(3.24) mini-watershed and it indicates that as this unit is situated on structural hill,

soil erosion is quite high in this area. The 2A2B5B4 has the lowestest elongation ratio (0.260)

indicating possibility of high erosion. Form factor values are in range of 0.39 to 0.46 which

indicates that the Bandu watershed has moderately high peak flow for shorter duration. The

compounded parameter is computed simply adding the ranks, giving equal weight to every

factor. The compound parameter values and prioritization rating of 25 mini-watersheds in

Bandu watershed is carried out through the table 4. 2A2B5A1, 2A2B5A5,

2A2B5A7,2A2B5A8, 2A2B5A9, 2A2B5A11, 2A2B5B5 mini-watershed with a compound

parameter value of 27.25 receives the highest priority (1) followed by 2A2B5 having the

compound parameter value of 6.25. Lowest priority has been given to the mini-watershed

number 2A2B5C2 which has compound parameter value of (11.38). Highest priority

indicates the maximum soil erosion in the specific mini-watershed and it must be given

maximum attention for soil conservation. The final priority map of the area under study is

shown. On the basis of priority map it can be recommended that 2A2B5A1 mini-watershed

should be given first priority for soil conservation measures and followed by other mini-

watersheds according to their rank of priority.

6. References

1. Das, Ghanashyam., (2000), Hydrology and Soil Conservation Engineering, Prentice

Hall of India, New Delhi.

2. IMSD Special Programme-Baghmundi Block, Puruliya District, West Bengal (1996),

State Remote Sensing Centre, DST & NES, Govt. of West Bengal, unpublished report.

3. Integrated Mission for Sustainable Development, Technical Guidelines, National

Remote Sensing Agency, Department of Space, Government of India, Balanagar,

Hyderabad-500037, December-1995.

4. Jala Bibhajika Unnayan Karmasuchi Parikalpana o Rupayaner Paddhatigata

Ruparekha, Paschimbanga Sarkar, Panchayat o Gramonnayon Daftar, Rajya

Panchayat o Gramonnayon Sangstha, Kalyani, Nadia.

5. Kuldeep Pareta, Upasana Pareta, (2011), Quantitative Morphometric Analysis of a

Watershed of Yamuna Basin, India using ASTER (DEM) Data and GIS, International

Journal of Geomatics and Geosciences, 2(1), pp 248-269.

6. National Remote Sensing Centre: Landuse/Landcover-50k (2005-06), Department of

Space, Government of India.

7. Natural (National) Resource, Information System Project, Puruliya District, West

Bengal, Unpublished Report.



Ajoy Das et al.,



8. NRIS Project, Project Report On Soil Mapping of Puruliya District, West Bengal,

Indian Resources Information and Management Technologies LTD., Plot No. 1299K,

Road No. 66, Jubilee Hills, Hyderabad-500033.

9. Rudraiah, Govinaiah, Vittala., (2008), Morphometry Using Remote Sensing and GIS

Techniques In The Sub-Basins of Kagna River Basin, Gulburga District, Karnataka,

India, Journal of Indian society of Remote Sensing 36, 351-360.

10. Seethapathi P.V, Dutta D, and Siva Kumar R., (2008), Hydrology of Small

Watersheds (eds), New Delhi: TERI (The Energy and Resources Institute).

11. Sethupathi. A.S , Lakshmi Narasimhan C , Vasanthamohan V , MohanS.P, (2011),

Prioritization of mini watersheds based on Morphometric analysis using Remote

Sensing and GIS techniques in a draught prone Bargur Mathur sub water sheds,

Ponnaiyar river basin, India, International Journal of Geomatics and Geosciences,

2(2), pp 403-414.

12. Sandipan Gosh, (2011), Quantitative and Spatial Analysis of Fluvial Erosion in

relation to Morphometric Attributes of Sarujharna Basin, East Singhbhum, Jharkhand,

International Journal of Geomatics and Geosciences, 2(1), pp 71-90.

13. Thakkar, A.K. and Dhiman, S.D., (2007), Morphometric Analysis and Prioritization

of miniwatersheds in Mohr Watershed, Gujarat Using Remote Sensing and GIS

technique, Journal of the Indian society of Remote Sensing, 35(4), 313-321.

Documents

Analysis of drainage morphometry and watershed ... · Map, Slope Map have been prepared. ... Figure 3: Drainage water and surface water body map ... hill area. Coarse loamy soil is