Sunday, 10 November 2013

Types of Erosion by Water:

Types of Erosion by Water:

  • Splash Erosion: Small soil particles are detached and sent airborne through the impact of raindrops on soil.
  • Sheet Erosion: Raindrops break apart the soil structure and it's moved downslope by water that flows overland as a sheet rather than definitive channels. This occurs frequently during cloud bursts.
  • Rill Erosion: This process develops small, short-lived, concentrated flow paths. These paths creates a sediment source and delivery system for hillslope erosion. Areas where precipitation rates exceed soil infiltration rates are more prone to this type of erosion.
  • Gully Erosion: Water flows in narrow channels during or directly following heavy rains or melting snow. The gullies can erode to considerable depths.
  • Valley or Stream Erosion: Continual water flow alongside land (along a linear feature) creates this type of erosion. It extends downward, deepening a valley, and headward, extending the valley into the hillside. This occurs most frequently in times of flooding.
  • Bank Erosion: Over time, banks of rivers and streams are naturally worn down.


Water Erosion Control:

The greatest way to restore eroded land is very simple: Vegetation. Plants grow and colonize creating deep root systems protecting the soil from water in its various forms. As simple as the solution is, a little help never hurts. Coir is natural coconut fiber that will protect the soil while the plants grow. Woven geotextiles and non-woven geotextilesseparate soils, filter water, and reinforce the ground.


Types of Erosion by Water:

Water Erosion Control Practices

Mulch, a type of protective covering which is in direct contact with the ground, provides more protection than canopy cover. It can vary from straw, to compost, to wood chips, or saw dust. Spread evenly onto the ground, mulch helps to reduce water evaporation, control weeds, and enrich the soil. It is also significant in protecting soil where vegetation has not had ample time to establish itself. By absorbing the destructive forces of raindrops and wind, mulch reduces erosion until the the seedlings mature enough to provide their own protective cover.

Terracing is a combination of contouring and land shaping in which earth embankments, or ridges, are designed to intercept runoff water and channel it to a specific outlet. Terraces reduce erosion by decreasing the steepness and length of the hillside slope and by preventing damage done by surface runoff.
There are basically two types of terraces:
  1. bench terraces
  2. broad base terraces
The bench terrace, perhaps one of the oldest forms of terraces, is used to reduce land slope. The broad base terrace, on the other hand, is used to control and retain surface water on sloping land.

  Grassed Linings
Vegetated waterways are built to protect soil against the erosive forces of concentrated runoff from sloping lands. By collecting and concentrating overland flow, waterways absorb the destructive energy which causes channel erosion and gully formation..
Waterways can have cross sections in parabolic, trapezoidal, or triangular form, depending on the functional requirements. Several of these requirements are climate, channel capacity, and desired flow velocity.
Grass linings should be hardy, dense - growing perennials adapted to the geographical region and soil. The grass should be cut periodically, fertilized as needed, and not subjected to prolonged traffic by either livestock or vehicles.

Contouring entails performing all tillage and planting of crops on or near the same elevation or "contour." It is applicable on relatively short slopes up to about 8 percent steepness with fairly stable soils. By planting across the slope, rather than up and down a hill, the contour ridges slow or stop the downhill flow of water. Water is held in between these contours, thus reducing water erosion and increasing soil moisture. Contouring's impact on annual soil loss rates vary with slope steepness, but typically it's reduced about one half from up - and - down hill farming when the slope is between 4 and 7 percent.


 
Strip cropping is a very effective and inexpensive method for controlling soil erosion. Strip cropping is a combination of contouring and crop rotation in which alternate strips of row crops and soil conserving crops (sods) are grown on the same slope, perpendicular to the wind or water flow. When soil is detached from the row crops by the forces of wind or water, the dense soil conserving crops trap some of the soil particles and reduce wind translation and/or runoff.

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