Technologies

Using Salix plant to protect stream banks [Nepal]

Baais ropi khola kinar samrakshan

technologies_1693 - Nepal

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Completeness: 71%

1. General information

1.2 Contact details of resource persons and institutions involved in the assessment and documentation of the Technology

Key resource person(s)

SLM specialist:

Shreedip Sigdel

SLM specialist:

Mulepati Indira

Department of Soil Conservation and Watershed Management

Nepal

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
Department of Soil Conservation and Watershed Mana (Department of Soil Conservation and Watershed Mana) - Nepal
Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
ICIMOD International Centre for Integrated Mountain Development (ICIMOD) - Nepal

1.3 Conditions regarding the use of data documented through WOCAT

The compiler and key resource person(s) accept the conditions regarding the use of data documented through WOCAT:

Ja

2. Description of the SLM Technology

2.1 Short description of the Technology

Definition of the Technology:

Stream banks can be protected by planting them with Salix (Salix babylonica); this is a traditional practice that has been used for streams that flow through agricultural lands.

2.2 Detailed description of the Technology

Description:

The erosion of stream banks is a natural geomorphic process, but when the streams flow through agricultural land there is a danger that they can overrun their banks and damage crops or erode land used for cultivation. The degree of erosion can be reduced by using structural measures such as lining the banks with concrete or large boulders or by planting trees along the edges. The Salix plant (Salix babylonica) has been found to be particularly useful for preventing erosion because its roots extend deep into the soil and help to anchor the bank. Following age-old tradition, land users in Bhaktapur district have planted Salix along the Bramayaeni khola (stream). It is a low-cost technology that is simple to implement.

Purpose of the Technology: Salix does best in moist soils, such as those found along irrigation channels and along the banks of rivers and streams. Salix saplings are most commonly planted in single rows but sometimes in double rows. After the saplings are planted, the entire area is fenced off using a biofence to protect them from being eaten or trampled by wild animals. Land users keep an eye on the Salix and prune or thin them as needed, for example when it is shading crops, or when they need firewood or can sell the branches.

2.3 Photos of the Technology

Media Gallery

2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment

Country:

Nepal

Further specification of location:

Bhaktapur Municipality-2, Nantukucha, Bhaktapur District

Specify the spread of the Technology:
  • applied at specific points/ concentrated on a small area
Comments:

Total area covered by the SLM Technology is 0.026 km2.

3. Classification of the SLM Technology

3.1 Main purpose(s) of the Technology

  • reduce, prevent, restore land degradation

3.2 Current land use type(s) where the Technology is applied

Cropland

Cropland

  • Annual cropping
Number of growing seasons per year:
  • 2
Comments:

Major land use problems (compiler’s opinion): When streams overflow their banks, agricultural land can be flooded and eroded.

3.5 SLM group to which the Technology belongs

  • improved plant varieties/ animal breeds
  • surface water management (spring, river, lakes, sea)

3.6 SLM measures comprising the Technology

vegetative measures

vegetative measures

  • V1: Tree and shrub cover

3.7 Main types of land degradation addressed by the Technology

soil erosion by water

soil erosion by water

  • Wr: riverbank erosion
Comments:

Main causes of degradation: floods

3.8 Prevention, reduction, or restoration of land degradation

Specify the goal of the Technology with regard to land degradation:
  • prevent land degradation

4. Technical specifications, implementation activities, inputs, and costs

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

Schematic diagram of a low cost riverbank protection scheme that can be implemented using mostly local materials.

Technical knowledge required for land users: moderate

Main technical functions: The Salix roots reinforce the soil and support it by buttressing and arching., Salix armours the slope against surface erosion

Secondary technical functions: Floodwater is safely channeled downstream

Author:

Bhojdeo Mandal, AK Thaku

4.2 General information regarding the calculation of inputs and costs

Specify how costs and inputs were calculated:
  • per Technology area
Indicate size and area unit:

ha

Specify currency used for cost calculations:
  • USD

4.3 Establishment activities

Activity Timing (season)
1. The planting site is cleared. Cuttings are taken from 3–5 year-old trees: average length: 2–2.5 m; average diameter: 5–7 mm. January-febuary
2. Planting pits approximately 30 cm in diameter and 90 cm deep are dug into the stream bank approximately 1–2 m apart.
3. The Salix cuttings are planted so that one-third of their length is below the surface of the soil.
4. After planting, the soil is compacted around the base of the cuttings.
5. The cuttings are watered soon after planning and again at least three times per month. In June and July, six months after planting, the cuttings that have survived and taken hold should show new shoots.

4.4 Costs and inputs needed for establishment

Specify input Unit Quantity Costs per Unit Total costs per input % of costs borne by land users
Labour Clear planting side persons/day/ha 150.0 3.9 585.0 100.0
Construction material Salix cutting ha 1.0 186.0 186.0 100.0
Total costs for establishment of the Technology 771.0
Total costs for establishment of the Technology in USD 771.0
Comments:

Duration of establishment phase: 2 month(s)

4.5 Maintenance/ recurrent activities

Activity Timing/ frequency
1. The established Salix is thinned or pruned if it is found to be shading crops. New cuttings are planted in areas where cuttings have failed to take root.

4.6 Costs and inputs needed for maintenance/ recurrent activities (per year)

Specify input Unit Quantity Costs per Unit Total costs per input % of costs borne by land users
Labour Thinning and prunning persons/day/ha 10.0 3.9 39.0 100.0
Construction material New salix cutting ha 1.0 35.0 35.0 100.0
Total costs for maintenance of the Technology 74.0
Total costs for maintenance of the Technology in USD 74.0

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

The labour cost is very high in Bhaktapur District; when compared to other parts of the country it is probably the highest. All costs and amounts are rough estimates by the technicians and authors

5. Natural and human environment

5.1 Climate

Annual rainfall
  • < 250 mm
  • 251-500 mm
  • 501-750 mm
  • 751-1,000 mm
  • 1,001-1,500 mm
  • 1,501-2,000 mm
  • 2,001-3,000 mm
  • 3,001-4,000 mm
  • > 4,000 mm
Agro-climatic zone
  • sub-humid

Thermal climate class: temperate

5.2 Topography

Slopes on average:
  • flat (0-2%)
  • gentle (3-5%)
  • moderate (6-10%)
  • rolling (11-15%)
  • hilly (16-30%)
  • steep (31-60%)
  • very steep (>60%)
Landforms:
  • plateau/plains
  • ridges
  • mountain slopes
  • hill slopes
  • footslopes
  • valley floors
Altitudinal zone:
  • 0-100 m a.s.l.
  • 101-500 m a.s.l.
  • 501-1,000 m a.s.l.
  • 1,001-1,500 m a.s.l.
  • 1,501-2,000 m a.s.l.
  • 2,001-2,500 m a.s.l.
  • 2,501-3,000 m a.s.l.
  • 3,001-4,000 m a.s.l.
  • > 4,000 m a.s.l.

5.3 Soils

Soil depth on average:
  • very shallow (0-20 cm)
  • shallow (21-50 cm)
  • moderately deep (51-80 cm)
  • deep (81-120 cm)
  • very deep (> 120 cm)
Soil texture (topsoil):
  • medium (loamy, silty)
Topsoil organic matter:
  • high (>3%)
If available, attach full soil description or specify the available information, e.g. soil type, soil PH/ acidity, Cation Exchange Capacity, nitrogen, salinity etc.

Soil fertility is high

Soil drainage / infiltration is good

Soil water storage capacity is medium

5.4 Water availability and quality

Ground water table:

> 50 m

Availability of surface water:

good

Water quality (untreated):

for agricultural use only (irrigation)

5.5 Biodiversity

Species diversity:
  • medium

5.6 Characteristics of land users applying the Technology

Market orientation of production system:
  • mixed (subsistence/ commercial)
Off-farm income:
  • > 50% of all income
Relative level of wealth:
  • rich
Individuals or groups:
  • individual/ household
Level of mechanization:
  • manual work
Indicate other relevant characteristics of the land users:

Population density: > 500 persons/km2

Annual population growth: 2% - 3%

5.7 Average area of land used by land users applying the Technology

  • < 0.5 ha
  • 0.5-1 ha
  • 1-2 ha
  • 2-5 ha
  • 5-15 ha
  • 15-50 ha
  • 50-100 ha
  • 100-500 ha
  • 500-1,000 ha
  • 1,000-10,000 ha
  • > 10,000 ha

5.8 Land ownership, land use rights, and water use rights

Land ownership:
  • individual, titled
Land use rights:
  • individual
Water use rights:
  • communal (organized)

5.9 Access to services and infrastructure

health:
  • poor
  • moderate
  • good
education:
  • poor
  • moderate
  • good
technical assistance:
  • poor
  • moderate
  • good
employment (e.g. off-farm):
  • poor
  • moderate
  • good
markets:
  • poor
  • moderate
  • good
energy:
  • poor
  • moderate
  • good
roads and transport:
  • poor
  • moderate
  • good
drinking water and sanitation:
  • poor
  • moderate
  • good
financial services:
  • poor
  • moderate
  • good

6. Impacts and concluding statements

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

fodder production

decreased
increased

risk of production failure

increased
decreased

production area

decreased
increased
Comments/ specify:

New land can be brought under cultivation

Income and costs

diversity of income sources

decreased
increased

Socio-cultural impacts

community institutions

weakened
strengthened

SLM/ land degradation knowledge

reduced
improved

livelihood and human well-being

reduced
improved
Comments/ specify:

Farm income is increased when more land is available for cultivation and when more fodder and fuelwood are available

Ecological impacts

Water cycle/ runoff

excess water drainage

reduced
improved

evaporation

increased
decreased
Soil

soil loss

increased
decreased
Biodiversity: vegetation, animals

biomass/ above ground C

decreased
increased
Climate and disaster risk reduction

flood impacts

increased
decreased
Comments/ specify:

reduced susceptibility to adverse events such as floods

Other ecological impacts

Salik can shade crop

increased
decreased

6.2 Off-site impacts the Technology has shown

water availability

decreased
increased
Comments/ specify:

Improved water availability downstream because water remains contained in the stream

damage on public/ private infrastructure

increased
reduced
Comments/ specify:

Reduced probability of flooding

6.3 Exposure and sensitivity of the Technology to gradual climate change and climate-related extremes/ disasters (as perceived by land users)

Gradual climate change

Gradual climate change
Season increase or decrease How does the Technology cope with it?
annual temperature increase well

Climate-related extremes (disasters)

Climatological disasters
How does the Technology cope with it?
drought not well
Hydrological disasters
How does the Technology cope with it?
general (river) flood well

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?
Short-term returns:

positive

Long-term returns:

very positive

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?
Short-term returns:

very positive

Long-term returns:

very positive

6.5 Adoption of the Technology

If available, quantify (no. of households and/ or area covered):

148 households

Of all those who have adopted the Technology, how many did so spontaneously, i.e. without receiving any material incentives/ payments?
  • 91-100%
Comments:

There is a strong trend towards spontaneous adoption of the Technology

Comments on adoption trend: All of the 148 households studied implement this technology voluntarily without external support.

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
It is a successful example of sustainable land management that has been very effective in Nepal.

How can they be sustained / enhanced? An awareness programme on the importance of stream bank protection would help to validate and reconfirm this age-old practice.
This low-cost technology is applied using indigenous knowledge.

How can they be sustained / enhanced? Scientific and technical input might help to make this technology more effective.

6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them

Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view How can they be overcome?
There are no funds to help extend the technology to other areas. More funding should be made available for stream bank protection either from the District Soil Conservation Office or private organizations.
When newly planted Salix cuttings are overrun by khosima, a new invasive species, they gradually die. Technical backstopping is needed for the removal of unwanted species.

7. References and links

7.1 Methods/ sources of information

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