Forms of water erosion

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Poornima S, AEC&RI, Kumulur, Trichy.

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Forms of water erosion

  1. 1. Splash erosion: • Caused by the impact of falling rain drops. • Factors determine rate of erosion : Climate, soil, Topography & Plant cover. • Impact of rainfall per unit area is determined by the no., & size of drops, & velocity of the drops. Forms of water erosion
  2. 2. Sheet erosion: • Uniform thin layer of removal of soil. • Splash – primary cause. • Detachment process – splash erosion & transportation of detached particles – wash erosion.
  3. 3. Rill erosion: (Micro channel erosion) • Advanced stage of sheet erosion. • Removal of soil by runoff water forms shallow channel. • Smoothened out by normal cultivation. • If rill neglected, forms into large gullies. • More in loose soil. • Transition stage b/w sheet & gully.
  4. 4. Gully erosion: • Advance & last stage of erosion. • Cannot be smoothened out by normal cultivation. • Principle: 1. Watershed area 2. Soil characteristics, alignments, size & shape of gully & slope in gully bed. • Main process : Water fall erosion & channel erosion.
  5. 5. Classification of gullies 1. Based on shape (c/s) : ‘U’ & ‘V’ shape 2. Based on state : Active & Inactive. 3. Based on dimension of the gully: Type Symbol Specification Side slopes Depth m Width m Very small G1 ≤ 3.0 < 18.0 vary Small G2 ≤ 3.0 ≥ 18.0 8 – 15% Medium G3 3.0-9.0 ≥ 18.0 8 – 15% Deep G4 > 9.0 vary Steep slope
  6. 6. Stages of gully development • Stage 1: Formation stage • Stage 2: Development stage • Stage 3: Healing stage • Stage 4: Stabilization stage
  7. 7. Ravines: • Series of gully opening • Interlocking pattern & drains into river. Causes: • Soil conditions & texture • Erratic rainfall • Improper land use by grazing • Faulty agril. Practices • Heavy biotic inference
  8. 8. Reclamation: • Closure to grazing & biotic inference • Adopt soil conservation measures Land slides: • Downward & outward movement of soil. Causes: • Geologic factors • Hydrological factors • Seismic factors Reclamation: • Increase vegetative covers • Establishment of walls

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