INDIAN SCHOOL OF MINES · INDIAN SCHOOL OF MINES Soil Erosion Hazard Evaluation By Integrating...

I NDI AN SCHOOL OF MI NES

So il Eros ion Hazard Evaluat ion By In t e grat ing Re vis e d Un ive rs al So il Los s Equat ion (RUSLE) Re vis e d Un ive rs al So il Los s Equat ion (RUSLE)

Wit h GIS Te c hn ique s

Dr. Dheeraj KumarDr. Dheeraj KumarKuldeep Pathak Dr. Dheeraj KumarDr. Dheeraj KumarB.TechB.Tech, M.Tech, Ph.D.(IIT KGP), M.Tech, Ph.D.(IIT KGP)Head, Mine Surveying SectionHead, Mine Surveying Section

dheeraj@dkumar.orgdheeraj@dkumar.org

Kuldeep PathakM.Tech (ISM Dhanbad)Survey Executive, Hindustan Zinc Ltd., India

• Quantitative Assessment of soil erosion iscumbersome and costly activity.cumbersome and costly activity.

• The advent of new techniques for erosionassessment and recent developments in Remoteassessment and recent developments in RemoteSensing and Geographic Information Systems (GIS)has promoted a prominent growth in the numberand variety of GIS based models.

Study area

• The study area is located in Nainital district ofUttrakhand in outer Himalayan region foothill zone,Uttrakhand in outer Himalayan region foothill zone,lies between 29°19'48 to 29°24'0 N latitude and79°26'24 to 79°34'12 E longitude.

• The land is highly to moderately populated, with fragile• The land is highly to moderately populated, with fragilesoils and steep slopes that are highly prone to soilerosion during the monsoon season.

•• The area is suffering with declining soil fertility due tohigh erosion and nutrient leaching through run-off.

RESEARCH OBJECTIVE

• To generate a spatial erosion map with RevisedUniversal Soil Loss Equation (RUSLE) methodUniversal Soil Loss Equation (RUSLE) methodand GIS techniques.

• To develop a numerical model for soil erosion• To develop a numerical model for soil erosionhazard assessment to compute a soil erosionhazard index.

• To assist erosion management strategies forefficient management of present and future erosiondisaster.disaster.

METHODOLOGY

• To choose most appropriate Soil Erosion EstimationMethod.Method.

• Data acquisition and preparation.

•• Hazard assessment by proper decision makingtechnique.

METHODOLOGYMETHODOLOGY

SOIL EROSION ESTIMATION METHOD

• Universal Soil Loss Equation/Revised Universal SoilLoss Equation (USLE/RUSLE)Loss Equation (USLE/RUSLE)

• Limburg Soil Erosion Model (LISEM)

•• European Soil Erosion Model (EUROSEM)

• Soil and Water Assessment Tool (SWAT)

• Others

The Revised Universal Soil Loss Equation The Revised Universal Soil Loss Equation The equation is the function of five input factors which are inraster format and soil erosion can be estimated within eachpixel.pixel.

A= ( R * K * LS * C * P )A= ( R * K * LS * C * P )

where:

• A is the computed spatial average of soil loss over a period

•• R factor is a measure of rainfall-based erosivity

• K factor is a measure of inherent soil surface erodibility

• LS factor is a measure of slope length and steepness• LS factor is a measure of slope length and steepness

• C factor is a measure of soil surface protective cover

• P factor is a measure of soil conservation or management• P factor is a measure of soil conservation or managementpractices

DATA ACQUISITION AND PREPARATION

• Satellite image , Landsat TM (Oct 24, 2011)

• DEM Digital Elevation Model, ASTER GLOBALDEM (Geo-referenced Tagged Image File Format)downloaded from USGS websitedownloaded from USGS website

• Soil attribute data

•• Monthly rain fall data from Indianmeteorological department.

DATA ACQUISITION AND PREPARATION

RAINFALL-RUNOFF EROSIVITY FACTOR (R)

• Rainfall erosivity is a term that is used to describe the potential for soil to washoff disturbed, de-vegetated areas and into surface waters of the state duringstorms.

• Rainfall data collected from Indian Meteorological Department (IMD) were used• Rainfall data collected from Indian Meteorological Department (IMD) were usedfor calculating R-factor using the following relationship developedby Renard and Feimund (1994):

Where R is the yearly rainfall erosivity factor (MJmmha-1 h-1 y-1), Pi is the monthlyrainfall (mm), and P is the annual rainfall (mm). F is the modified Fourierrainfall (mm), and P is the annual rainfall (mm). F is the modified Fouriercoefficient

SOIL ERODIBILITY FACTOR (K)

• Soil erodibility factor K represents both susceptibilityof soil to erosion and the rate of runoff, as measuredof soil to erosion and the rate of runoff, as measuredunder the standard unit plot condition.

• To generate individual factor map for K, the method• To generate individual factor map for K, the methodwhich was followed is shown in Eq. (William andRenard,1983):

Where Sd, Si, Cl and C represent sand (%), silt (%), clay(%) and carbon (%), respectively.(%) and carbon (%), respectively.

TEXTURE OF THE SOIL (SAMPLE TESTED)

K-FACTOR MAP K-FACTOR MAP

SLOPE LENGTH AND STEEPNESS FACTOR (LS)

• L is the slope length factor, representing the effectof slope length on erosion.of slope length on erosion.

• LS-factor is computed by means of ArcInfo ArcGISSpatial analyst extension using the DEM followingSpatial analyst extension using the DEM followingthe equation as proposed by Moore and Burch(1986a, b)(1986a, b)

Pow(([flow accumulation] * 30) / 22.13, 0.4) *Pow(Sin([slope] / 0.896), 1.3)Pow(Sin([slope] / 0.896), 1.3)

FLOW ACCUMULATIONFLOW ACCUMULATION

SLOPE FACTOR MAPSLOPE FACTOR MAP

LS FACTOR MAPLS FACTOR MAP

COVER MANAGEMENT FACTOR (C)

• The C-factor is used to determine the relativeeffectiveness of soil management system ineffectiveness of soil management system interms of preventing soil loss.

• The Normalized Difference Vegetation Index(NDVI), an indicator of the vegetation vigor and(NDVI), an indicator of the vegetation vigor andhealth is used to generate the C-factor valueimage for the study area (Zhou et al., 2008; Kouliet al., 2009).et al., 2009).

• Command in raster calculator is:(Exp(( - 2)[ndvi] / (1-[ndvi])

COVER MANAGEMENT FACTOR MAPCOVER MANAGEMENT FACTOR MAP

CONSERVATION PRACTICE FACTOR (P)CONSERVATION PRACTICE FACTOR (P)

• The support practice factor (P-factor) is the soil-lossratio with a specific support practice to theratio with a specific support practice to thecorresponding soil loss with up and down slopetillage (Renard et al., 1997).

• In the present study the P-factor map was derived• In the present study the P-factor map was derivedfrom the land use/land cover and support factors.

• the P factor was assigned according to theconservation practice in the area which ranges fromconservation practice in the area which ranges from0.0 to 1.0, with the highest value assigned to areaswith no conservation practices.

CONSERVATION PRACTICE FACTOR MAP

EROSION ESTIMATION MAP

• The erosion estimation map is prepared by RUSLE equation by multiplying each component map in raster calculator tool of ArcGIS. in raster calculator tool of ArcGIS.

HAZARD ASSESSMENTHAZARD ASSESSMENT

• Approach to decomposition-analysis-aggregationwas used for the initial, ill-defined evaluation criteria.was used for the initial, ill-defined evaluation criteria.

• Analytical hierarchy process (AHP) (Saaty,1977)approach was used for standardization of differentapproach was used for standardization of differentcriteria.

• The relevant criteria for soil erosion by water are soilerodibility, slope, soil depth, rainfall, elevation,erodibility, slope, soil depth, rainfall, elevation,vegetation, population density and the presence ofexisting soil erosion.

STANDARDIZATIONSTANDARDIZATION• In this study the AHP

utilizing expert judgmentwas used to determine thewas used to determine thedegree of hazard.

• First, a decision-makermakes a comparisonmakes a comparisonbetween each elementunder evaluation. Later,these are converted tothese are converted toquantitative values using ascale designed by Saaty(1977):

Standardized weighted maps of selected factors

E

COMPUTATION OF HAZARD INDEXCOMPUTATION OF HAZARD INDEXPair-wise comparison matrix for standardized factor maps:

Using these values from table the final model for Hazard index can be stated as :Hxy= (8.09108)S1 + (6.373)S2 + (4.52682)S3 + (10)S4 + (1.42785)S5 + (5.9577)S6 + (2.53019)S7 +Hxy= (8.09108)S1 + (6.373)S2 + (4.52682)S3 + (10)S4 + (1.42785)S5 + (5.9577)S6 + (2.53019)S7 +(1.029235)S8

RESULT AND DISCUSSION

STATISTICS OF GRADED SOIL EROSION HAZARD

SOIL EROSION HAZARD MAP

Soil erosion hazard with soil erosion rate

Hazard class Rate of Soil erosion Management strategies

SOIL EROSION MANAGEMENT STRATEGIES

Hazard class Rate of Soil erosion Management strategies

Very low to low(0-181)

Low (=244 t/h/year) These areas should be protected strictly with very lesshuman activities and Lumbering.

ModerateLow (=244 t/h/year) Should be protected from vegetation degradation and

removal and made stabilize with proper plantation.Moderate(181-214)

removal and made stabilize with proper plantation.

Moderate (244-754 t/h/year) Lumbering, human activities, vegetation degradation shouldbe stopped .Stabilization through plantation.

High to veryhigh (>214)

Low (=244 t/h/year) Proper land use planning is needed as conservation tillage,suitable cropping pattern as there is probability that the rateof erosion will increase.

Moderate (244-754 t/h/year) Environment impact assessment must be performed andModerate (244-754 t/h/year) Environment impact assessment must be performed andcrop rotation practice should be done with soil managementprogram.

High (=754 t/h/year) On emergency basis priority should be given to control andprotect areas from erosion. Conservation tillage and otherprotect areas from erosion. Conservation tillage and otherengineering structures (contour banding, contourhedgerows) should be properly implemented.

CONCLUSION

1. Soil erosion hazard map along with annual soil loss map can be

effectively used to formulate appropriate managementeffectively used to formulate appropriate management

strategies for protection and conservation of soil erosion.

2. By appropriate adjustment of some local influence factors, the2. By appropriate adjustment of some local influence factors, the

model could be applied to other regions. Hence, hazard index is

considered useful for spatial planning for policy maker andconsidered useful for spatial planning for policy maker and

planning authorities, particularly to soil scientists and

conservationists.