ESTABLISHING PERMISSIBLE EROSION RATES FOR VARIOUS LANDFORMS IN DELHI STATE INDIA

Abstract

PERMISSIBLE EROSION RATES ALSO KNOWN AS SOIL LOSS TOLERANCE ( T VALUE) IS DEFINED AS A MAXIMUM EROSION THAT TAKE PLACE ON A GIVEN SOIL WITHOUT DEGRADING ITS LONG- TERM PRODUCTIVITY . IN INDIA DEFAULT T VALUE OF 11.2 MG HA-1 YR-1 IS USED FOR DEVISING LAND RESTORATION STRATEGIES FOR DIFFERENT TYPES OF SOILS. HOW EVER THE ABILITY OF SOIL TO RESIST DEGRADATION VARIES WITH SOIL TYPE, DEPTH AND PHYSICO - CHEMICAL FEATURES. THEREFORE, THE PRESENT INVESTIGATION WAS UNDERTAKEN TO DETERMINE T VALUE OF DIFFERENT LANDFORMS OF DELHI STATE BY TAKING INTO ACCOUNT SOIL SATURATED HYDRAULIC CONDUCTIVITY (SHC), BULK DENSITY (BD) , ORGANIC CARBON, ERODIBILITY AND SOIL pH . SOIL STATE WAS DEFINED BY A QUANTITATIVE MODEL AND SCALING FUNCTIONS WERE USED TO CONVERT SOIL PARAMETERS TO A 0-1 SCALE. THE NORMALISE VALUES WERE MULTIPLIED BY APPROPRIATE WEIGHING FACTORS BASED ON RELATIVE IMPORTANCE AND SENSITIVITY ANALYSIS OF EACH INDICATOR. CATEGORIAL RANKINGS OF I, II AND III WERE ASSIGNED TO SOIL GROUPS BASED ON OVERALL AGGREGATE SCORE. T VALUE OF DIFFERENT LANDFORMS OF DELHI STATE WAS COMPUTED USING GUIDELINES OF USDA- NATURAL RESOURCE CONSERVATION SERVICES. MAJORITY OF LANDFORMS OF DELHI AND T VALUE RANGED FROM OF 12.5 MG HA-1 YR-1 EXCEPT FOR SOILS OF THE HILL TERRAIN. DISECTED HILLS, PEDIMENT AND PIEDMONT PLAIN, WHERE T VALUE RANGED FROM 5 TO 10 MG HA-1 YR-1 . THESE T VALUE COULD BE USED FOR CONSERVATION PLANNING AND WILL HELP THE PLANNERS IN DEVISING SUITABLE LAND RESTORATION STRATEGIES.