Soil Erosion Control using Geo synthetics
key words- soil erosion. environmental problems, geo synthetic, slope stability
Erosion of soil takes place due to the action of flowing water, rain water or wind. The soil particles then get displaced which in turn creates various engineering and environmental problems. It is therefore very essential to prevent soil erosion. There are different methods to arrest the erosion. One of the effective and economical methods is the use of geo synthetic mats for erosion control.
Introduction
Soil erosion takes place when the shear force generated due to the external agencies such as wind and flowing water exceeds the shearing resistance of the soil particles. To control soil erosion, the shear resistance has to be increased.
Due to erosion, the banks of rivers may cut into the natural ground, road/ railway embankments may collapse leading to serious catastrophes. In case of agricultural soils, the top layer of soil may get depleted and may lead to the loss of fertile soil. It is reported that the soil is swept and washed faster than natural replenishment to the tune of 10 times in USA and 30 to 40 times faster in China and India.
Erosion can be controlled by different methods as natural vegetation, turfing, rip-rap, stone pitching, mats and gabions. But for the last fifty years, geo synthetic materials are being used in large quantities.
Characteristics of Soil Erosion
The main factors affecting erosion are intensity of rain, quantity of rain, duration, slope of the ground and soil permeability.
The types of erosion are - splash, sheet, shore line and rill & gully.
The processes involved in erosion are - detachment, transportation and deposition.
Geo synthetics
Geo means earth or soil and synthetics means man-made. Geo synthetics are made from petrochemical based polymers (plastics) which are biologically inert and will not decompose from bacterial or fungi actions. These are porous fibers manufactured from synthetic materials such as polypropylene, polyester, polyethylene, nylon, polyvinyl chloride and different mixes of these items. They are available in different thicknesses and widths in rolls of various lengths. These fabrics are durable and strong and can with stand hostile soil environment.
These geo synthetic mats are placed on or in the soil to improve slope stability of embankments, hill sides, and river / stream banks. Different geo synthetic materials are geo- textiles, geo- grids, geo- cells, geo- membranes and erosion control materials.
Method of Installation
- Level and compact the area after removing vegetation, debris, stones and other discarded materials.
- Lay the mat and anchor it at the toe of slope properly.
- Construct gabions at the slope benches
Advantages of Geosynthetic Mats
The main advantages of geo synthetic mats are: Easy and quick installation, economical, environmental friendly, maximum root anchorage, helps in the growth of vegetation and reduces water and wind velocities.
Conclusions
Erosion is a natural phenomenon and can’t be avoided altogether. But its effects can be reduced by taking suitable methods. One such effective and economical method is the use of geo synthetics for the control of erosion.
Image courtesy: http://www.flickr.com/photos/drainage-erosion-virginia/4293695138/
References:
1. Principles of Soil Mechanics and Foundation Engineering, V N S Murthy,UBS Publishers and Distributors, New Delhi,1992
2. Construction Engineering and Management, S Seetharaman, Umesh Publications, Delhi, 2003
3.Construction and Foundation Engineering, J Jha, S K Sinha, Khanna Publishers,Delhi,1977
Links:
www.erosiopollution.com
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