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AP 610 PHYSICS OF SOIL AND WATER EROSION AND THEIR CONTROL                     (2L+1P) II

Objective
  To teach the physical factors and processes describing erosion, its estimation , measurement of soil loss and runoff and methods of erosion control in arable and non-arable lands.

Theory

UNIT I
  Factor affecting soil erosion by water: Effect of climate: Rainfall erosivity- kinetic energy of rainfall, Wischmeir’s equation for its prediction, rainfall erosivity indices, isoerodent map of India. Effect of soil: Soil erodibility- soil physical parameters affecting soil erodibilty and its measurement, various indices of soil erodibility. Effect of topography, crop cover and soil management on soil erosion.

UNIT II
  Method of soil loss estimation and measurement; Universal Soil Loss Equation(USLE): Estimation of various factors effecting erosion by water, soil loss tolerance, applicability and limitations of USLE and its revision .Water erosion prediction programme (WEPP)- sediment transport equations: rate of sediment detachment ,transport and deposition, sediment transport capacity, rill and inter rill erodibility and their measurement in field. Measurement of different types of soil erosion: Splash erosion and its measurement. Measurement of rill and gully erosion. Use of remote sensing methods for delineating different eroded areas according to their severity.

UNIT III
  Runoff measurement & estimation : Gauges for long term/average prediction of stages of rivers and streams, stage level recorder for measuring short term variations of water levels, current meters for measurement of water discharge , hydrographs; Calibrated devices for runoff measurement: Theory of sub and super critical flow. Flumes, weirs and orifice - types, equations for calculating water head, suitable conditions for their use and their installation in field; Methods for runoff estimation: Rational formula, soil cover complex/ curve number method;

UNIT IV
  Sediment measurement: Multislot divisor, cshocton wheel sampler, point and depth integrated sediment samplers;

UNIT V
  Soil and water conservation: Concept of watershed: need for implementation of soil and water conservation programmes on watershed basis, Size of  watershed, understanding concept of integrated water shed management through case studies. Outline of steps of integrated watershed management plan. Characterization and management of watersheds using remote sensing and GIS, Land capability classification: land capability classes, sub-classes and units

UNIT VI
  Methods of erosion control in arable and nonarable lands: contour farming ,strip cropping, physical techniques of conservation forestry, bunds, terraces, ponds, gabion check dams, drop structures, trenches ,retention walls and spurs. Problems of soil and water erosion in India & conservation techniques: Types of soil erosion by water in different parts of India & their control measures – Hill side erosion, ravines, erosion on black soils, torrents, landslides, erosion due to mining and seaside erosion, water harvesting & recycling: water harvesting techniques for alfisols, vertisols, inceptisols and aridsols, methods for controlling seepage losses.

UNIT VII
  Wind erosion-wind velocity, initiation and movement of soil particles, siltation, suspension and surface creep and mechanics involved, soil physical properties affecting wind erosion, wind erosion equation and its computation, control of wind erosion.

Practicals
  Computation of Kinetic energy of falling rain drops and Wishmeir’s formula, Measurement of  Land slope, erosivity index (EI30) using rain gauge data, Determination of erodibility Indices, Land capability classification of a watershed, sediment discharge estimation from a river basin, sediment detachment and transport rates, transport capacity, rill and interrill erodibility from field runoff and soil loss measurements, soil loss estimation using RUSLE software.

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