Bench terracing
Transcript of Bench terracing
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Benching(Bench Terracing)
Presented to:
Dr. Abdul Rehman
Presented by:
Ali Adnan
BAGF14E260
7th Agronomy
College of Agriculture, University of Sargodha
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Definition
Bench terraces are a series of level or virtually level strips running
across the slope at vertical intervals, supported by steep banks or risers.
• It is an engineering soil conservation practice
• It is also called bench terracing.
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History
• Concept of bench terracing is old as agriculture itself.
• Philippines started bench terracing 2500 years ago.
US soil conservation services collected evidences:
• In Israel, citrus orchard in southern France, ShanSi province(China)
and Lebanon hill side.
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Objectives
• To reduce run-off or its velocity and to minimize soil erosion.
• To conserve soil moisture and fertility and to facilitate cropping
operations.
• To promote intensive land use and permanent agriculture on slopes
and reduce shifting cultivation
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Applicability
This practice can:
• Be manage on soil having slopes up to 30 %.
• Be done where there is deep heavy clay soil rather than in very sandy soil.
• Typically not applicable for slopes of decomposed granitic material, or any significantly sandy soil, because of excessive sloughing of material and construction difficulties.
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Locations and conditions for use
Bench terraces are particularly suited to countries or communities with the following macro conditions:
• Severe erosion hazards
• Areas with small holdings and a dense population.
• Areas where there are food shortages or high unemployment rates.
• Areas where crops require flood irrigation
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Cont..
For micro or site conditions, bench terracing is suitable in the following cases:
• Where there are relatively deep soils.
• On slopes not exceeding 25 degrees.
• On sites which are not dissected by gullies and not too stony.
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Cut and Fill method
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Types of Bench Terracing
1. Level or Table top bench terrace
2. Sloping inwards bench terrace
3. Sloping outwards bench terrace
4. Conservation type bench terrace
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Level or Table top bench terraceTable top bench terrace are suitable for:
• Areas receiving medium rainfall
• Areas having highly permeable and deep soils
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Sloping inwards bench terraceSloping inwards bench terrace are suitable for:
• Areas receiving heavy rainfall.
Sloping inwards bench terraceSloping inwards bench terrace are suitable for
• It is useful for crops susceptible to water lodging.
• Runoff towards hillside.
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Sloping outwards bench terrace:Sloping outwards bench terrace are suitable for:
• Areas receiving low rainfall & permeable soil of medium depth. at lower ends graded channels are provided for safe disposal of runoff
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Conservation type bench terrace
In this type of terrace:
• Modified form of level terrace
• Use moisture of uncropped area
• Barrier is established across the land at suitable interval and the terrace is developed by pushing soil downhill and subsequent natural leveling.
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Advantages
• Reduces the soil erosion.
• Aesthetical value
• Intensive land use.
• Economically beneficial.
• Availability of food for local area.
• Flood chances can be reduce.
• Improves the condition of the slope for plant establishment.
• Reduces runoff velocities and increases infiltration.
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Disadvantages
• Highly labor demand and time consuming.
• Increased cost relative to alternative slope stabilization techniques.
• Can be complicated to design and install, and may fail if not properly designed and installed
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Some examples over the world
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Terraces in northern Luzon Philippines
2000-B.C
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Citrus Orchard in southern France
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Lebanon hill side
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Level bench terracing in Japan
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Tea on bench terraces, Bhutan
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Outward bench terrace in Korea
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Terraces on eroded soils of Israel
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Terraced Fields in Sa Pa, Vietnam
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Rice Terrace Panorama in Bali
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Swat Valley, Pakistan
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Grassy Terraces in Chitral, Pakistan
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Kashmir, Pakistan
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Thank You