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WEL-COME

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Bioengineering methods for soil erosion control

Prepared by: Santosh pathak

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Bio-engineering methods:

integrated technology that uses sound engineering practices in conjuction with ecological principles to:

design & construct vegetative living system to prevent erosion, stabilize shallow areas of soil instability, protect and enhance healthy system.

uses live plant materials and flexible engineering techniques to eliminate environmental problems.

Different combination of methods can be used on cut and fill slopes along roadways, landfill covers, spoil banks and streambanks.

On areas of existing or potential mass wasting, it may be best to use a bio engineered system alone or in combination with soil bioengineering.

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Construction of engineering structures are expensive, alternative cheap option so in our cases there is a need of alternative conservation methods which can be adopted with less expenditure, use locally available materials and environmentally friendly……Bioengineering

To control the surface erosion on fill slope, napier was grown in Shivapuri Watershed road erosion control program.

Many landslides affected areas like Krishna Bhir are rehabilitated by the uses of bioengineering measures.

Advantages:

1) low cost and lower long term maintenance cost.

2) low maintenance of live plants after establishment.

3) environmental benefit of wildlife habitat.

4) water quality improvement.

5) compatibility with enviromentally sensitive sites.

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Soil conservation practices by Bio-engineering measures

Riprap

stone pitching is done with vegetation inter-planted between the stones; usually on gully floor

It is made from variety of rock types, commonly granite or limestones, and occasionally concrete rubble from building.

used to stabilize streambanks, provide in –stream channel stability and provide a stable outlet.

absorb and deflect the energy of waves before they reach the defended structure.

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The vegetation like nilkanda, asuro, saiiwan, simali etc are grown.

Riprap stone can be built at any time, but planting should be done before monsoon.

Slopes on which riprap is used to stabilize streambanks should be no steeper than 1.5:1.

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Grass waterways Grass waterways is earth waterway planted with

grasses (such as . dubo, centipede grass) to control soil erosion

Waterways are important for removing surplus water from terraced field and for erosion control. They are constructed along the slope of area (<20%).

2-m to 48m wide The uses of grasses in this measures act as lining

material to control the problem of erosion caused by turbulent runoff flow through the section.

allows increasing soil cohesion and roughness.(reduce K),

also prevents the formation of rills and gullies.

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Advantages:

a) It carries large flow and make it suitable for large watershed.

b) Farm machineries can easily cross them.

c) After establishment of grasses, its maintenance become very easy.

Disadvantages:

a) It restricts the installation of the drainage outlet.

b) At few location the establishment of vegetation is being very difficult.

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Fascine: A fascine is a rough bundle of brushwood or other

material used for strengthening an earthen structure, or making a path across uneven or wet terrain.

Typical uses are protecting the banks of stream from erosion, covering marshy ground and so on. In the war they are often used to create paths for tanks and other vehicles across uneven terrain.

Fascine spacing : 4m for < 30 degree slope; 2m for 30-45 degree slope.

Trench 10-20 cm deep, 20 cm wide (may vary according to site).

For each fascine, there should be at least 4 but not more than 8 cuttings.

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Jute netting This is a net made of jute that is laid and anchored

over straw or other mulch to protect the mulch from wind and water damage.

It reduces soil erosion and provides a good environment for vegetative regrowth. Jute is a biodegradable material that will eventually decompose and is not a threat to the environment.

This practices is often used on areas that may erode near structures such as homes, roads, and bridges.

Jute can be applied alone( without mulch) as an alternative to straw or wood mulches on flat sites for dust control and seed germination enhancement.

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Procedure:

Jute nets are placed on slopes or degraded land with the help of the stakes.

Seeds or cuttings can be placed inside.

Natural regeneration takes place on time.

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Wattling Rows of fence of live cutting across the slope. Catches debris, slope modification. Phaledo, Bains, Dabdabe, Kavro,Khirro- as stakes.

Design: Long stakes: 100cm long, 4-6 cm diameter. Short stakes: 50 cm long, 3-4 cm diameter. Insert 100cm long stakes at intervals of about 1m,

insert two 50 cm long stakes in between the long stakes.

Place the vegetative cuttings between the stakes as live fence(asuro, nilkanda, sajiwan, simali).

Wattling spacing: 100-200cm on steep slopes

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