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Internal Guide:

Dr. PRADEEP. P. LODHAAssociate Professor & Head

Civil Engineering Dept.,

G.E.C - Valsad

External Guide:

Dr.INDRA PRAKASH,

Faculty

BISAG

Gandhinagar

STUDY OF SOIL EROSION FOR VISHWAMITRI RIVER WATERSHED

USING REMOTE SENSING AND GEOGRAPHIC INFORMATION SYSTEM

By

VISHVAM H. PANCHOLI (130280712013)

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Contents

Importance of Watershed management Introduction to Remote Sensing and Geographic Information

System Objective of present study Introduction to study area Estimation of Soil Erosion using Universal Soil Loss

Equation(USLE) Calculation of R,K,L,S,C,P factor References & Useful links

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IMPORTANCE OF WATERSHED MANAGEMENT

1) WM is used to Conservation, Development and optimal utilization of land

and water resources for benefit to people.

2) Land Development (Agriculture, Forest etc.)

3) Development of Water Harvesting Structures

i). Check Dam

ii). Recharge well

iii). Recharge bore stone pitching

4) Nursery Rising

i). Timber

ii). Fuel Wood

iii). Horticultural Species.

5) Drinking water Facilities

6) Controlling Degradation of land (such as Erosion Control)

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Remote Sensing(RS) is used for

1). Image Interpretation

2). Analysis of images into various Fields

like Agriculture, soil, water.

Geo Informatics System(GIS) is a

tool for

1). Capture,

2). Storage,

3). Retrieval and Manipulation,

4). Display and querying data

5). Decision making.

INTRODUCTION TO RS AND GIS

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OBJECTIVE & METHODOLOGY OF PRESENT STUDY

OBJECTIVE:1. To calculate annual Soil Erosion using Universal Soil Loss Equation (USLE).

METHODOLOGY:

1. Preparation of Thematic maps (Land use/Land cover, Soil, Slope) using ArcGIS Software.

2. Estimation of Soil Erosion using Universal Soil Loss Equation (USLE) which is following as A=R*K*LS*C*P.

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The Vishwamitri River originates

from the hills of Pavagadh in

Gujarat.

It flows west through the Vadodara

city and empties into the Gulf of

Khambat of Gujarat State.

Vishwamitri River Watershed is

located between 22 00’ and 22 45’

of North Latitude and 73 00’ and 73

45’ of East Longitude in

Panchmahal and Vadodara, in

Gujarat State. CONT.

INTRODUCTION TO STUDY AREA

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Annual rainfall varies from 850

to 1000 mm. Most of rainfall is

received during the mid-June to

early October.

The total area of the Vishwamitri

watershed is 1185 km2 .

INTRODUCTION TO STUDY AREA (CONT.)

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THEMATIC MAPS

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THEMATIC MAPS

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LAND USE MAP WITH CLASSIFICATION

Sr.noLand use type Area in

sq.km1 Agriculture 931.14

2 Built up 121.81

3 Forest 3.33

4 Waste land 51.51

5 Water bodies 36.68

6 Others 40.52

1185.0

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SOIL MAP WITH CLASSIFICATION

Sr.no soil type Area in sq.km

1 Very fine sand 126.3

2 Fine sand 826.0

3 Fine loamy 177.1

4 Coarse loamy 55.7

1185.0

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SLOPE MAP WITH CLASSIFICATION

Sr.noSlope range

Area in Sq.km

1 0 - 1 % 1178.5

2 1 - 3 % 2.0

3 3 - 5 % 0.3

4 5 - 10 % 1.9

5 10 - 15 % 0.5

6 15 - 35 % 1.8

    1185.0

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INTRODUCTION TO SOIL EROSION

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Soil Erosion is the washing or blowing away by (Water or

Wind) removal of Top Layer of Soil. It is a Natural Process

Generally It Is Not Visually Identify.

Small particleDetachment

Transportation Depos

ition

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UNIVERSAL SOIL LOSS EQUATION (USLE):

The Universal Soil Loss Equation (USLE) an empirical model for predicting the annual soil loss caused by rainfall was developed by Wischmeier and Smith (1965).

The Universal Soil Loss Equation (USLE) widely applied at watershed scale to predicts the long-term annual rate of erosion on a field slope based on rainfall pattern, soil type, topography, crop system and management practices (Williams and Berndt,1972,1977).

The Universal Soil Loss Equation is defined as, A=R*K*LS*C*PWhere,A= Annual computed Soil Loss (ton/ha/year)R=Rainfall Erosivity factor

K=Soil Erodibility factorLS= Slope-length factor C= Crop management factor

P= Supporting Practice management factor

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METHODOLOGY :

All Five factors (i.e. R,K,LS,C and P) of USLE Equation are calculated as per above methodology.

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In present study, calculation of Soil Erosion using USLE based on Sub watershed level.

Vishwamitri river watershed has four sub watersheds (SW1, SW2, SW3, SW4) given above in Figure with area.

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RAINFALL EROSIVITY (R) FACTOR:

The R factor was determined using formula given below (Chaudhry and Nayak, 2003).

Ra=79+0.363*Xa Where, Ra = Annual R factor,

Xa= Average Annual Rainfall in mm. In present study, Rainfall data for 5 rainguage stations are available for

estimating the R factor, such as Halol, Wadala Tank, Vadodara, Waghodia, Pilol.

Station name Rainfall in mm R factor(Ra=79+0.363*Xa)

Halol 1062.55 464.71Wadala Tank 677.18 324.82

Vadodara 1020.48 449.43Waghodia 867.70 393.97

Pilol 869.28 394.55

Table 1: Calculated R- factor

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The average Calculated R-Factor is given below in Table-2.

Sr. No Sub watershed Calculated R-factor

1 SW1 627.12

2 SW2 920.85

3 SW3 974.92

4 SW4 449.43

Table 2: Calculated average R- factor

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SOIL ERODIBILITY (K) FACTOR:

Soil Erodibility factor represents the soil susceptibility to detachment and transport of soil particles under an amount of runoff for specific rainfall.

In the Vishwamitri river watershed consist of soil texture classes namely 1) Course loamy 2) Fine & very fine sand 3) Fine loamy sand.

Based upon several studies , organic matter content for vishwamitri river watershed is considered as 2%.

K values for different soil textures has defined by the stewert et.al (1975) in Table-3.

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Sr.no Sub watershed

Code

K-factor

1 SW1 0.26

2 SW2 0.25

3 SW3 0.28

4 SW4 0.26

As per the stewert et.al chart is value of K- factor is taken. The Calculated Average K-Factor is given below in Table-4.

Table 3: K- factor value (stewart et.al) Table 4: Calculated average K- factor

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SLOPE LENGTH & STEEPNESS (LS) FACTOR

The slope length and slope steepness can be used in a single index, which expresses the ratio of soil loss as defined by Wischmeier (1978).

LS = (X/22.1) m (0.065 + 0.045 S + 0.0065 S)2

here, X = slope length (m or km); S = slope gradient (%)

Slope value was derived from Digital Elevation Model (DEM) of vishwamitri river watershed. The values of X and S were derived from DEM.

To calculate the slope length (X) value, Flow Accumulation was derived from the DEM after conducting Fill and Flow Direction processes by using Arc Hydro tool in ArcGIS 9.3.

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The value of m varies from 0.2 –0.5 depending of the slope (Wischmeier and Smith1978).

Using Raster calculator plot the below equation for LS factor map. LS= (("Fac"*25/22.1)^0.2)*(0.065+0.045*"Slope"+0.0065*("Slope"*"Slope"))

Sr.no Sub watershed Code LS factor

1 SW1 3.43

2 SW2 3.41

3 SW3 0.12

4 SW4 0.29

Table 5- Calculated LS factor

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Procedure for LS factor procedure

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CROP MANAGEMENT (C) FACTOR

The crop management factor is used to reflect the effect of cropping and management purpose on erosion rates.

It is considered the second major factor (after topography) controlling soil erosion.

The C factor is calculated depending upon different land use types as per below Table (Wischmeier and Smith 1978).

Land use Sub Land use C-factor

Agriculture

Current Fallow 0.6

Kharif + Rabi (Double cropped) 0.6

Kharif Crop 0.5

Plantations 0.5

Buit up

Commercial 0.2

Industrial 0.2

Towns/cities (Urban) 0.2

Villages (Rural) 0.2

Forest Scrub Forest 0.02

Others Prosophis and Quarry 0.15

Waste land Land with Scrub 0.95

Land without Scrub 0.8

Water bodies Canal, Lakes, Rivers 0

Table 6: Values of C- factor

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As per given value of C- factor by Wischmeier and Smith in Table 6.The Average Calculated C-Factor for present study is given below in Table-7.

Table 7: Calculated Average C-factor

Sr.no Sub watershed code

C-factor

1 SW1 0.30

2 SW2 0.31

3 SW3 0.34

4 SW4 0.31

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CONSERVATION PRACTICE (P) FACTOR:

Conservation practice factor (P) in USLE expresses the effect of conservation practices that reduce the amount and rate of runoff, which reduces soil erosion.

It includes different types of agricultural management practices such as:

Strip cropping, Contour farming, and terracing etc.

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The value of P–factor ranges from 0 to 1, in which highest value is assigned to areas with no conservation practices .

Average P-factor is calculated as given in Table-9 .

Table 8: P factor on different slope gradient

Sr.no Slope percentage (%) P factor

1 0 - 1 % 0.62 1 - 3 % 0.63 3 - 5 % 0.54 5 - 10 % 0.55 10 - 15 % 0.76 15 - 35 % 1

Table 9: Calculated average P factor

Sr.no

Sub watershed

code

P-factor

1 SW1 0.58

2 SW2 0.58

3 SW3 0.60

4 SW4 0.60

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SOIL EROSION CALCULATION A Quantitative assessment of vishwamitri river watershed

is taken place using USLE. All five parameters of Universal Soil Loss Equation (USLE)

is calculated for each four sub watershed. After calculation of all five parameters, annual soil erosion

of vishwamitri river watershed is 240.27 ton /ha/year.

Sub watershed

Code

R-factor

K-factor

LS-Factor

C-factor

P-factor

Annual Soil

Erosion

SW1 627.12 0.26 3.43 0.3 0.58 97.31

SW2 920.85 0.25 3.14 0.31 0.58 129.97

SW3 974.92 0.28 0.12 0.34 0.6 6.68

SW4 449.43 0.26 0.29 0.31 0.6 6.30

Total Annual Soil Erosion 240.27

Table 10:Annual Soil Erosion for different sub watershed

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Sr.no

Sub watershed

Code

Annual Soil

Erosion

Class group

Priority

1 SW1 97.31Very

Severe2

2 SW2 129.97Very

Severe1

3 SW3 6.68 Moderate 34 SW4 6.30 Moderate 4

Table-11: Classes of soil erosion & prioritization Vishwamitri watershed

The computed Annual Soil loss of study area is 240.27 ton /ha/year.

It is found that sub watershed coded as SW2 is in very severe condition which needs to provide controlling measures.

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CONCLUSION:

Soil erosion study is carried out for Vishwamitri River watershed using Universal Soil Loss Equation.

The computed Annual Soil loss of study area is 240.27 ton /ha/year.

After calculating all five parameters of USLE, it is found that two sub watersheds coded as SW1 & SW2 are subjected to very severe condition which needs to provide controlling measures.

Remaining two sub watersheds coded as SW3 & SW4 are subjected to Moderate condition.

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REFERENCES:Agricultural Handbook Number 537, “Prediction Rainfall Erosion losses- A guide to conservation Planning”,

U.S.Department of Agriculture, Dec-1978

A.S.Ravikumar, H.B.Balakrishna, B.K.Anand, Watershed management and Impact of Environmental changes on

Water Resources-Page no-512-521.

Biswas et.al, 1999. Prioritization of Sub watershed based on Morphometric Analysis of Drainage Basin: A remote

sensing and GIS approach Journal of the Indian Society of Remote Sensing, (pg.155-166).

Chauhan Parul, Jadav Rita, P.P.Lodha. “Critical Watershed Analysis for Soil Conservation Management using Swat

model”. Hydraulics and Water Resources: National Conference on Hydraulics and Water Resources (Hydro-2007),

December21-22, 2007

Dr. Lodha, Pradeepkumar P. “ GIS Based Framework for Integrated Watershed Management with Livelihood

Linkages ”, January-2006.

Ghanshyam Das (2000): Hydrology & Soil Conservation Eng. Prentice Hall of India, New Delhi.

Handbook of Hydrology (1972), Soil Conservation Department, New Delhi.

Murthy JVS. Watershed Management In India,(pg.21-34).

Smith and Wischmer (1941), Interpretation of soil conservation data for field use. Agriculture Engineering (page no .173-175)

USDA manual for Soil Conservation Service (1985), National Engineering Handbook, USA.

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http://www.omafra.gov.on.ca/english/engineer/facts/12-053.html

http://www.soilerosion.net/ http://www.vishwamitririverproject.org/

USEFUL LINKS:

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