Unexpected flood risk control in village [Nepal]
- Creation:
- Update:
- Compiler: Sabita Aryal
- Editor: –
- Reviewers: David Streiff, Alexandra Gavilano
Bhelbadi Niyantran
technologies_1590 - Nepal
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Expand all Collapse all1. 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:
Koirala Pratiksha
Nepal
Gautam Bibhu
Nepal
Mulmi Anjuli
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:
Yes
2. Description of the SLM Technology
2.1 Short description of the Technology
Definition of the Technology:
It is a technology used to control and reduce the effects of downstream flood by physical interventions like construction of spillway, ditch and stone dam on the wall of ditch.
2.2 Detailed description of the Technology
Description:
Hilly areas are prone to flash flood that occur with little warning. During rainy season, level of water rises in the stream due to which land mass field of around area was degraded. This technology is used to control the land mass and water flowing from upper region to the lower region of the hill. The natural stream was modified to deep and more sloppy. And surrounding walls were made by piling up stones dams and tighten them by metal wires. These dams decrease the slope gradient and reduce the velocity of water flow and promote the deposition of eroded materials.
Purpose of the Technology: There was no problem of landslide and downstream flood before. But after the road construction, soil became loose resulting in the occurrence of downstream flood. It caused massive destruction of agricultural fields and disturbed settlement areas. Also, stone and gravel during landslide and stream flood used to be deposited and block the flow of the water. So land user invented by this technology to control and reduce the effects of downstream flood.
Establishment / maintenance activities and inputs: Land users and other villagers took the initiative to carry out the technology. Stones were abundantly found in the stream that were utilized to make the dams on lining the stream. Dozer was used to deepen the stream and increase the slope of stream. Stones were piled up and tied by iron wires on the bank of stream by local farmers themselves with their own investment.
Natural / human environment: The area where this technology has been used is a hilly area. Soil fertility in that area is low or medium which differs according to the place. Due to landslide and downstream flood, sand and gravel get deposited in the cropland, so its fertility is very low. No crops can be grown in there. This technology helps to control further degradation of land but could't help to restore natural quality of land.
This area is semi arid area. Due to the proper supply of water the area is prevented from drying. People living in that area are mainly farmers and depend on agriculture for livelihood. Also the area is developing more after the road construction. People are now being more aware about health, education and development.
2.3 Photos of the Technology
2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment
Country:
Nepal
Region/ State/ Province:
Nepal
Further specification of location:
Kavre
Specify the spread of the Technology:
- applied at specific points/ concentrated on a small area
Comments:
The area occupied by SLM technology is approximately 28 km2. It includes area occupied by conversation measures and the additional area protected by them.
Map
×2.6 Date of implementation
If precise year is not known, indicate approximate date:
- less than 10 years ago (recently)
2.7 Introduction of the Technology
Specify how the Technology was introduced:
- through land users' innovation
Comments (type of project, etc.):
The problem of downstream flood was caused before two years after the construction of road. so technology was also developed before 2 years.
3. Classification of the SLM Technology
3.1 Main purpose(s) of the Technology
- reduce, prevent, restore land degradation
- reduce risk of disasters
3.2 Current land use type(s) where the Technology is applied
Waterways, waterbodies, wetlands
- Waterway, ditch
Comments:
Major land use problems (compiler’s opinion): Cropland destruction
Major land use problems (land users’ perception): Cropland destruction, vegetation destruction, decreased soil fertility.
Constraints of waterway/ditch (Ditch for the flow of water): Big stone which block the water ways.
Number of growing seasons per year: 3
Longest growing period in days: 150; Longest growing period from month to month: june-november; Second longest growing period in days: 90; Second longest growing period from month to month: march-june
3.5 SLM group to which the Technology belongs
- surface water management (spring, river, lakes, sea)
3.6 SLM measures comprising the Technology
structural measures
- S3: Graded ditches, channels, waterways
- S6: Walls, barriers, palisades, fences
3.7 Main types of land degradation addressed by the Technology
soil erosion by water
- Wg: gully erosion/ gullying
- Wo: offsite degradation effects
Comments:
Main causes of degradation: urbanisation and infrastructure development (Construction of road i.e infrastructure development), floods (Downstream flood during rainy season.), inputs and infrastructure: (roads, markets, distribution of water points, other, …) (Road construction)
Secondary causes of degradation: Heavy / extreme rainfall (intensity/amounts) (Heavy rainfall during rainy season cause downstream flooding.)
3.8 Prevention, reduction, or restoration of land degradation
Specify the goal of the Technology with regard to land degradation:
- prevent land degradation
Comments:
Secondary goals: mitigation / reduction of land degradation, rehabilitation / reclamation of denuded land
4. Technical specifications, implementation activities, inputs, and costs
4.1 Technical drawing of the Technology
Technical specifications (related to technical drawing):
This technical drawing shows the constructed dam and gully which allow proper flow of downstream flood.
Location: Chyamrangbes. Kavre
Technical knowledge required for land users: high
Technical knowledge required for labour: high (Through their experience to construct in a useful way.)
Main technical functions: control of concentrated runoff: drain / divert, reduction of slope angle
Secondary technical functions: control of dispersed runoff: retain / trap, improvement of surface structure (crusting, sealing)
Diversion ditch/ drainage
Vertical interval between structures (m): n'a
Spacing between structures (m): n'a
Depth of ditches/pits/dams (m): 2.13
Width of ditches/pits/dams (m): 3.2
Length of ditches/pits/dams (m): 1000
Height of bunds/banks/others (m): 1.6
Width of bunds/banks/others (m): 0.8
Length of bunds/banks/others (m): 1000
Construction material (earth): Soil excavate from the ditches is used to build bank.
Construction material (stone): the cut off ditch is lined with stones, embankment with stones.
Construction material (other): iron wire was used to bind the stone together.
Slope (which determines the spacing indicated above): 12%
Author:
Bibhu Gautam, KUGH,Kavre
4.2 General information regarding the calculation of inputs and costs
Specify currency used for cost calculations:
- USD
4.3 Establishment activities
Activity | Timing (season) | |
---|---|---|
1. | Land user increased the width and slope of existing ditch for easy flow of water. | dry seasonm |
2. | Land user embanked the bank with stones on either side. | dry season |
3. | Stones are bind together by wires in some places. | dry season |
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 | Increase the width and slope of ditch | ha | 1.0 | 941.17 | 941.17 | 100.0 |
Total costs for establishment of the Technology | 941.17 | |||||
Total costs for establishment of the Technology in USD | 941.17 |
Comments:
Duration of establishment phase: 2 month(s)
4.6 Costs and inputs needed for maintenance/ recurrent activities (per year)
Comments:
Machinery/ tools: dozer, Dozer
The above mentioned cost is not given per unit/hectar. It is the total cost used for that technology.
4.7 Most important factors affecting the costs
Describe the most determinate factors affecting the costs:
The most determinate factor affecting the cost is land structure. Land contains loamy soil which made it difficult for construction of ditch.
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
Specifications/ comments on rainfall:
monsoon rain, dry winter
Agro-climatic zone
- semi-arid
Thermal climate class: subtropics
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.
Indicate if the Technology is specifically applied in:
- concave situations
Comments and further specifications on topography:
Slopes on average: The average slope is about 15%.
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):
- coarse/ light (sandy)
Topsoil organic matter:
- low (<1%)
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 texture: Sandy and graveled land
Soil fertility is medium - low and varies according to soil texture
Soil drainage / infiltration is poor
Soil water storage capacity is low, soil is sandy and contains gravel. So it cannot store water
5.4 Water availability and quality
Ground water table:
on surface
Availability of surface water:
excess
Water quality (untreated):
unusable
Comments and further specifications on water quality and quantity:
Ground water table: Infiltration is very low. Water only flow on surface.
Availability of surface water: During rainy season excess water flow through the steam.
Water quality (untreated): Some portion water is used in agriculture
5.5 Biodiversity
Species diversity:
- low
Comments and further specifications on biodiversity:
Soil is very infertile. So it is poor in biodiversity.
5.6 Characteristics of land users applying the Technology
Off-farm income:
- less than 10% of all income
Relative level of wealth:
- average
- rich
Individuals or groups:
- groups/ community
Gender:
- women
- men
Indicate other relevant characteristics of the land users:
Land users applying the Technology are mainly common / average land users
Difference in the involvement of women and men: More male because women cannot do such type of heavy labor work.
Population density: 50-100 persons/km2
Annual population growth: 2% - 3%
(living standard is more than average).
(average life standard).
Off-farm income specification: Their land is protected from further degradation
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
Is this considered small-, medium- or large-scale (referring to local context)?
- small-scale
5.8 Land ownership, land use rights, and water use rights
Land ownership:
- individual, not titled
Land use rights:
- communal (organized)
Comments:
The land where SLM technology is applied belongs to individual, but it land use right belongs to community.
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
risk of production failure
Quantity before SLM:
n/a
Quantity after SLM:
n/a
Comments/ specify:
protected the cropland from flood
Socio-cultural impacts
SLM/ land degradation knowledge
Quantity before SLM:
n/a
Quantity after SLM:
n/a
Comments/ specify:
active participating people on land conservation.
Ecological impacts
Water cycle/ runoff
surface runoff
Comments/ specify:
water travel in fixed path
excess water drainage
Comments/ specify:
improved water way for passage of excess water
Soil
soil loss
Comments/ specify:
soil loss due to flooding is reduced
6.2 Off-site impacts the Technology has shown
downstream flooding
Comments/ specify:
the main benefits of this technology
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)
Meteorological disasters
How does the Technology cope with it? | |
---|---|
local rainstorm | not well |
local windstorm | not known |
Climatological disasters
How does the Technology cope with it? | |
---|---|
drought | well |
Hydrological disasters
How does the Technology cope with it? | |
---|---|
general (river) flood | not well |
Comments:
Dame can be made more tolerant again flash flood by using wire to tighten the stone walls or making the concrete wall.
6.4 Cost-benefit analysis
How do the benefits compare with the establishment costs (from land users’ perspective)?
Short-term returns:
negative
Long-term returns:
slightly negative
Comments:
This technology is not a investment purpose. People used their own money to construct it.
6.5 Adoption of the Technology
- single cases/ experimental
If available, quantify (no. of households and/ or area covered):
14 households in an area of 10 - 100 sq km (50 - 100 persons per sq km)
Of all those who have adopted the Technology, how many did so spontaneously, i.e. without receiving any material incentives/ payments?
- 0-10%
Comments:
100% of land user families have adopted the Technology with external material support
14 land user families have adopted the Technology with external material support
Comments on acceptance with external material support: Iron wire was provided by Bagmati watershed.
There is a strong trend towards spontaneous adoption of the Technology
Comments on adoption trend: People have well accepted this technology.
6.7 Strengths/ advantages/ opportunities of the Technology
Strengths/ advantages/ opportunities in the land user’s view |
---|
Risk of downstream flood and landslide is reduced. How can they be sustained / enhanced? If they had been more donation from government or any other projects, they would construct concrete or more flood resistance dams. As some parts are still unconstructed they would complete them with some more external support. |
Agriculture land get protected so they can plant the crop without being at risk. |
Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view |
---|
Proper water drainage system and water can get collected in the river following the fix path. How can they be sustained / enhanced? Fodder plant could be grown on the stream banks which is now left and unused. This could be used to feed the animals and would also help to control flood and landslide. |
It reduced the risk of further land degradation by downstream flood. How can they be sustained / enhanced? Dams can be made more strong by making concrete walls |
6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them
Weaknesses/ disadvantages/ risks in the land user’s view | How can they be overcome? |
---|---|
N/A |
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view | How can they be overcome? |
---|---|
N/A | N/A |
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