I NDI AN SCHOOL OF MI NES Soil Erosion Hazard Evaluation By Integrating Revised Universal Soil Loss Equation (RUSLE) Revised Universal Soil Loss Equation (RUSLE) With GIS Techniques Dr. Dheeraj Kumar Dr. Dheeraj Kumar Dr. Dheeraj Kumar Dr. Dheeraj Kumar Kuldeep Pathak Kuldeep Pathak B.Tech B.Tech , M.Tech, Ph.D.(IIT KGP) , M.Tech, Ph.D.(IIT KGP) M.Tech (ISM Dhanbad) Head, Mine Surveying Section Head, Mine Surveying Section Survey Executive, Hindustan Zinc Ltd., India dheeraj@dkumar.org dheeraj@dkumar.org
• Quantitative Assessment of soil erosion is cumbersome and costly activity . cumbersome and costly activity . • The advent of new techniques for erosion assessment and recent developments in Remote assessment and recent developments in Remote Sensing and Geographic Information Systems (GIS) has promoted a prominent growth in the number and variety of GIS based models .
Study area • The study area is located in Nainital district of Uttrakhand in outer Himalayan region foothill zone, Uttrakhand in outer Himalayan region foothill zone, lies between 29 ° 19 ' 48 to 29 ° 24 '0 N latitude and 79 ° 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 fragile soils and steep slopes that are highly prone to soil erosion during the monsoon season . • The area is suffering with declining soil fertility due to high erosion and nutrient leaching through run- off .
RESEARCH OBJECTIVE • To generate a spatial erosion map with Revised Universal Soil Loss Equation (RUSLE) method Universal Soil Loss Equation (RUSLE) method and GIS techniques . • To develop a numerical model for soil erosion • To develop a numerical model for soil erosion hazard assessment to compute a soil erosion hazard index . • To assist erosion management strategies for efficient management of present and future erosion disaster . disaster .
METHODOLOGY • To choose most appropriate Soil Erosion Estimation Method . Method . • Data acquisition and preparation . • Hazard assessment by proper decision making technique .
METHODOLOGY METHODOLOGY
SOIL EROSION ESTIMATION METHOD • Universal Soil Loss Equation/Revised Universal Soil Loss 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 in raster format and soil erosion can be estimated within each pixel . 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 management practices
DATA ACQUISITION AND PREPARATION • Satellite image , Landsat TM (Oct 24, 2011) • DEM Digital Elevation Model, ASTER GLOBAL DEM (Geo - referenced Tagged Image File Format) downloaded from USGS website downloaded from USGS website • Soil attribute data • • Monthly rain fall data from Indian meteorological 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 wash off disturbed, de - vegetated areas and into surface waters of the state during storms. • • Rainfall data collected from Indian Meteorological Department (IMD) were used Rainfall data collected from Indian Meteorological Department (IMD) were used for calculating R- factor using the following relationship developed by Renard and Feimund ( 1994 ): Where R is the yearly rainfall erosivity factor (MJmmha -1 h-1 y-1 ), Pi is the monthly rainfall (mm), and P is the annual rainfall (mm) . F is the modified Fourier rainfall (mm), and P is the annual rainfall (mm) . F is the modified Fourier coefficient
SOIL ERODIBILITY FACTOR (K) • Soil erodibility factor K represents both susceptibility of soil to erosion and the rate of runoff, as measured of soil to erosion and the rate of runoff, as measured under the standard unit plot condition . • To generate individual factor map for K, the method • To generate individual factor map for K, the method which was followed is shown in Eq . (William and Renard, 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 effect of slope length on erosion. of slope length on erosion. • LS-factor is computed by means of ArcInfo ArcGIS Spatial analyst extension using the DEM following Spatial analyst extension using the DEM following the 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 ACCUMULATION FLOW ACCUMULATION
SLOPE FACTOR MAP SLOPE FACTOR MAP
LS FACTOR MAP LS FACTOR MAP
COVER MANAGEMENT FACTOR (C) • The C- factor is used to determine the relative effectiveness of effectiveness of soil management system in soil management system in terms of preventing soil loss . • The Normalized Difference Vegetation Index (NDVI), an indicator of the vegetation vigor and (NDVI), an indicator of the vegetation vigor and health is used to generate the C- factor value image for the study area (Zhou et al ., 2008 ; Kouli et al . , 2009 ) . et al . , 2009 ) . • Command in raster calculator is : ( Exp (( - 2 )[ ndvi ] / (1-[ ndvi ])
COVER MANAGEMENT FACTOR MAP COVER MANAGEMENT FACTOR MAP
CONSERVATION PRACTICE FACTOR (P) CONSERVATION PRACTICE FACTOR (P) • The support practice factor (P - factor) is the soil - loss ratio ratio with with a a specific specific support support practice practice to to the the corresponding soil loss with up and down slope tillage ( Renard et al ., 1997 ). • In the present study the P- factor map was derived • In the present study the P- factor map was derived from the land use/land cover and support factors . • the P factor was assigned according to the conservation practice in the area which ranges from conservation practice in the area which ranges from 0.0 to 1.0, with the highest value assigned to areas with 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 ASSESSMENT HAZARD ASSESSMENT • Approach to decomposition - analysis -aggregation was 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 different approach was used for standardization of different criteria . • The relevant criteria for soil erosion by water are soil erodibility, erodibility, slope, slope, soil depth, soil depth, rainfall, rainfall, elevation, elevation, vegetation, population density and the presence of existing soil erosion .
STANDARDIZATION STANDARDIZATION • In this study the AHP utilizing expert judgment was used to determine the was used to determine the degree of hazard . • First, a decision - maker makes makes a a comparison comparison between each element under evaluation . Later, these these are are converted converted to to quantitative values using a scale designed by Saaty ( 1977 ):
Standardized weighted maps of selected factors
E
COMPUTATION OF HAZARD INDEX COMPUTATION OF HAZARD INDEX Pair -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 )S 1 + (6. 373 )S 2 + (4. 52682 )S 3 + ( 10 )S 4 + (1. 42785 )S 5 + (5. 9577 )S 6 + (2. 53019 )S 7 + Hxy = (8. 09108 )S 1 + (6. 373 )S 2 + (4. 52682 )S 3 + ( 10 )S 4 + (1. 42785 )S 5 + (5. 9577 )S 6 + (2. 53019 )S 7 + (1. 029235 )S 8
RESULT AND DISCUSSION
STATISTICS OF GRADED SOIL EROSION HAZARD
SOIL EROSION HAZARD MAP
Soil erosion hazard with soil erosion rate
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