Use Of Natural Geotextiles in Severe Erosion Control: A Local-Are

7/30/2019 Use Of Natural Geotextiles in Severe Erosion Control: A Local-Are

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What is Soil erosion? Why is itharmful?

The removal of the soil, especially its top layer, is termedas soil erosion. It destroys the soil, its properties

& characteristics.

Due to erosion, the soil loses its fertility and vegetativecapacity. Even in some cases, due to erosion, the soilbecomes prone to landslides and other disasters.

A view from my research visitto Keonjhar Mines in Odisha



What is Slope erosion?

The erosion from a soil slope is known as Slope Erosion.

Slope erosion has been a major erosional type in the land sector. There are

numerous kinds of slope erosion. They may be natural as in natural uncovered

slopes or anthropogenic as in case of mining soil dumps, uncovered slope due

to construction etc... This type of erosion has caused a great amount of damage to the land especially the anthropogenic mode of slope erosion.

It also results in slope failures causing landslides, especially during

construction. Slope Erosion from mine spoils destroy the surrounding land

completely, taking away its usability & fertility.

An erosional site inHingula Mines inTalcher, Odisha, India



What is Riverine Erosion?

The erosion due to the direct action of the river, is called asriverine erosion.

Riverine erosion is another major type of erosion of the land. It has been seen in most

high flow rivers and at many places along its bank where it has either soft soil or high

current. It destroys the land quality of the adjoining areas. So, it has caused muchdestruction to many villages, buildings etc…

Severe erosion byRiver Mahanadi inOdisha, India



What are Geosynthetics ?

It includes a variety of materials like

Geotextiles, Geogrids, Geomembranes,

Geonets, Geosynthetics clay liners,

Geofoam, Geocells & Geocomposites.

These range of materials are mostly

synthetic in nature and are used for civil

engineering purposes.

But here, I intend to use them for curbing

soil erosion. Here with 'them', I mean the

natural geotextiles.

Geosynthetics refer to a class of materials that are used to improve

the physical, mechanical & hydraulic

properties of the soil.



Various Natural Fibres Tested

To find a perfect fibre for our purpose of curbing soil erosion, idid a lot of research on locally availlable items, such as:• Tala chheli from Tala or Palm(Borassus flabellifer)• Khajuri patra from Khajuri or Date Palm (Phoenix dactylifera)• Juna (Chrysopogon zizanioides)• Hensa (Saccharum munja)• Jute fibres from Jute (Corchorus capsularis)• Coir Fibres from Coconut Palm (Cocos nucifera)• Incerapa cylindrica

Some of my testing samples

Out of theses Jute & Coir were foundto be most suitable for furtherresearch.



Why Jute & Coir?

•Good Pliancy•Render a high degree of

flexibility & finenessthat helps in fabricconstruction

•Consistency in tenacity•High torisional rigidity•Low percent of

Elongation-at-break•High drapability etc...

Some of the geotextile samples I made



Role of Geotextile in slope ErosionControl

Geotextile (GT), a 3-D fabric, when laid on the slope surface initially givesprotection against soil disintegration due to rain splash. Weft yarns of the GT

lying across the direction of flow act as mini check dams and reduce the velocity of flow. Besides reducing the velocity of overland flow, the apertures of the

fabric entrap the disintegrated soil particles that start carried away with it. Additional advantage is both in respect of velocity reduction and particleentrapment. The moisture in GT creates a congenial climate conductive to

growth of vegetation. Within one or two months vegetation starts sprouting.Ultimately after about one year or more, as per the case, GT coalesces with the

soil on bio degradation, adding nutrients to the soil.



My Experiments on it

• We made a soil bed with resemblance to the natural soil and covered one half

of it with geotextiles while the other half was left bare. Then this soil bed was put

on a stand with adjustable slope angle. Then water was poured over it with the

help of a motor Rainer.

• We also made many tweaks such as we changed the soil, the slope angle as

well as the amount of the rain shower. All the observations were taken and theconclusion was drawn that these geotextiles were completely efficient in curbing

slope erosion. All the data is available in the experimental data section.



Evolving a general procedure forcurbing slope erosion

After the research, I evolved out a general procedure for curbing slope

erosion.

First step is selecting the required geotextile, then,the following sequence is

followed, so that we can get the most benefits in order to curb the slope

erosion:

• If possible lay grass seeds

• Fixing of the geotextile on the slope

• Nailing it to fix it on site

• Anchoring the geotextileThis will result in stopping the erosion & well as ambient place for

vegetation, leading to natural slope stabilization.



Role of Geotextile in Riverine ErosionControl

In the case of riverine erosion, it is the current of the river as well as the soft soil of the bank that

results in the erosion. The river water hits the bank, and penetrates into the bank soil to some extent

and while receding back, it also sculpts out some soil with it.

So, to stop it the geotextile acts as a penetrable shield. The water enters through the geotextile and

comes out through it, but the geotextile acts as a filter and stops it from taking away the soil, thus

protecting it from erosion.



My Experiments on it• In a large tank of water, I created a false river bank. I attached flow pipes on

either side of the tank parallel to the bank in order to maintain the water flow. I alsohad the disturbance simulators attached to the pool side opposite to the bank.

• On the bank side half of it was covered with geotextile & the other was left

bare. I compared the amount of erosion on each side.

• Also I tweaked with the speed of the water flow, the amount of disturbances

etc…And at last took all our observations which can be found in the experimental data

section and found out the conclusion that the geotextiles are very effective in curbingthe riverine erosion.



Evolving a general procedure forcurbing Riverine erosion

After the research, I evolved out a general procedure for curbing riverine

erosion.

First step is selecting the required geotextile, then,the following sequence is

followed, so that we can get the most benefits in order to curb the riverine

erosion:

• Fixing of the geotextile on tarza mat

• Laying of geotextile – tarza mat composite on the river bed

• Anchoring the geotextile on the river bank

• Laying of two layers of boulder filled wire crates on the thegeotextile-tarza mat composite

This will result in stopping the erosion & well as ambient place for

vegetation, leading to natural bank stabilization.



Benefits of Natural Geotextiles

Natural geotextiles, dominantly jute geotextile, facilitate and quicken growth of vegetative-cover

soil. Vegetation once grown dissipates substantially the kinetic energy of rain drops, serves as a

receptor and absorbent of moisture and surface run-off. The wind, which has a sweeping effect,

is also prevented from disintegrating soil-particles. Surface rugosity of vegetation also attenuates

the velocity of surface run-off. Its root system ensures soil-integration and imparts strength to

the soil body. Soil permeability is also improved. JGT has proved to be an ideal nourisher of

vegetation in initial stages of its growth. It also improves the soil texture & properties.

Moreover its 'eco' characteristics help the environment to be clean also. In addition to that, it is

not also very expensive, which makes it rather attractive.



Drawbacks: Maintenance Requirment

Minor repairing work of the geotextiles laid-slants may be required after monsoon

season for one or two years. Inspection of geotextile-laid areas is needed within 24

hours after each rainfall or periods of heavy winds or daily during periods of

prolonged rainfall. Inspections and consequent action should be continued until

vegetative cover is established.

But this drawback is not big enough from stopping us to save our soil using naturalgeotextiles.



My Tested Sites & Benefits to thepeople

I used my idea at many local places like Santhapada, Talcher thermal etc...The people liked the idea so much, looking at the benefits that theypromptly accepted it.

Santhapada Bharatpur Open Cast Hingula



Conclusion

After gaining so much success, it would be impossible to notto use such a great idea. So, it can be safely concluded thatNatural Geotextiles are completely capable of controlling

about 87%-94% soil erosion of slopes & rivers.

Use Of Natural Geotextiles in Severe Erosion Control: A Local-Are

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