Micro irrigation canal system for supplying water to poplar plantations on sloping lands.
The Micro Irrigation system technology is documented by SLM Project/HELVETAS Swiss Intercooperation with financial support of Swiss Agency for Development and Cooperation (SDC). The presented micro-irrigation system, a structural SLM technology, was applied in Central Highland’s Province of Bamyan (Afghanistan). The micro-irrigation technology is applied to bring marginal land under cultivation for economic benefits, with the added benefit of rehabilitating degraded sloping land. The main irrigation canal also conveys water to agricultural land. It is a traditional technology applied by a land user without external support. It is also implemented by many other land users with some variations to the technology.
The technology consists of a network of main irrigation canal, secondary canals from which water is conveyed to sloping micro irrigation canals. The water reaches to the roots of each tree through infiltration/seepage.
The main canal has about 2% gradient and the micro-channels from 2-7% gradient. The slope of the site ranges between 20-40%. A micro irrigation canal is 28 m long, 15 cm wide and 10 cm deep. While the cross section remains same, the length can differ according to the land size.
The site was originally a degraded site with gravel soil. According to the land user, the site was not at all suitable for agriculture due to soil degradation and bad water shortage possibilities. Approximately 25 years after the plantation of poplar trees, the site's physical and biological conditions of the slope have improved due to the establishment of poplar trees. The poplar trees can be used for timber for construction and firewood. The poplar timber has good market in Bamyan and can fetch up to 35 USD per tree.
The micro-irrigation systems, which help establishing poplar plantations, contribute to multiple benefits for the land user's family and also the environment. As the poplar plantations are irrigated, their growth increases and their mortality, due to water shortage, is reduced.
As a result of re-vegetating the relatively steep slope, soil erosion from the site has reduced and the fertility of the soil has improved. Improved soil moisture and fertility has also helped in establishment of a good ground canopy. Many birds visit the site for shelter. The plantation has reached its harvesting stage and the land user is planning to cut the trees for sale, expecting an income of about 10,500 USD from the site.
A close look at this technology shows that the system works well and that it is easily managed by the land user. Some minor improvements, such as reducing the slope gradient of the micro-irrigation canals for reducing canal erosion, construction of pits to capture sediments at the drainage points and planting suitable grasses with good roots along the canal bunds could make the system more effective and sustainable. The measures could also help in reducing the sensitivity of the micro-irrigation canals towards intense rainfall.
The farmers are applying this SLM technology without any external financial or technical support and there is growing trend towards spontaneous adoption. According to the land user's estimate, of about 400 families in his village, 80 families have applied the technology
The basic purpose of the micro-irrigation system is to supply irrigation water to the poplar trees for reducing plant mortality and increasing plant growth.
The main establishment activities include layout of the micro canals across the sloping land using shovels and pick axe without use of any alignment equipment. Approximately 150 persons-days/ha were employed for constructing the micro-irrigation canals and 5 person-days/ha sufficed for on-site maintenance works. About 970 USD/ha was spent on the construction and most of the cost for labour was covered by the family of the owner.
The site is owned by a land user with clear land use rights. The water rights are common and organized as there is a traditional social water management institution (Mirab), which ensures an equitable distribution of irrigation water to all the farmers taking water from the main canal. A command area on a turn-by-turn basis exists. Water users pay service fees to the Mirab mostly in kind. The land users mentioned that they give about 14 kg of wheat and/or potato each year to the Mirab for this site. The land user has to also participate in main canal repair works on a voluntary basis. Bamyan Centre receives about 230 mm rainfall per year. Most of the rain falls in the months of April and May. Winters are severe with temperatures falling below minus 20 degrees. The area receives snowfall up to 180 cm per year in normal years. Bamyan center has an arid and temperate climate with one main growing season of about 6 months, which is from April to September. The plantation site is located at an altitude of about 2300 m. It is north-facing slope with a soil depth of about 30-50 cm. The soil is sandy loam with a medium soil fertility.
- 0.1-1 平方千米
Total area covered by the SLM Technology is 0.16 km2.
The technology is being applied on the site since about 25 years.
Major land use problems (compiler’s opinion): Gravely site, shortage of water for irrigation, sloping land affected by soil erosion. Heavy shrub harvesting for firewood and overgrazing on common/rangeland leading to land degradation.
Major land use problems (land users’ perception): Sloping land with sandy soil unsuitable for agriculture.
Plantation forestry: Plantation of poplar trees (mono culture)
Problems / comments regarding forest use: Land users do selective felling when they need cash. The trees are lopped for fuel wood.
Future (final) land use (after implementation of SLM Technology): Forests / woodlands: Fp: Plantations, afforestations
Number of growing seasons per year: 1
Longest growing period in days: 170, Longest growing period from month to month: April to September in the valley bottom
Main causes of degradation: over-exploitation of vegetation for domestic use (Particulary for firewood), overgrazing (Mainly by sheep and goats), population pressure, inputs and infrastructure: (roads, markets, distribution of water points, other, …) (Lack of irrigation water), governance / institutional (Specifically in the case of common lands)
Secondary causes of degradation: droughts
Technical specifications of micro-irrigation system for poplar plantation. The system comprises main canal, secondary canals and micro irrigation canals which receive water from and drain into secondary canals.
Location: Tape Chauni. Bamyan Centre
Date: 10 May 2014
Technical knowledge required for field staff / advisors: low
Technical knowledge required for land users: low
Main technical functions: water harvesting / increase water supply
Secondary technical functions: increase of biomass (quantity)
Vertical interval between structures (m): 0.22-0.6
Spacing between structures (m): 1.8-2
Depth of ditches/pits/dams (m): 0.1
Width of ditches/pits/dams (m): 0.15
Length of ditches/pits/dams (m): 0.28
Construction material (earth): Soil from the site is used for canal consturction
Slope (which determines the spacing indicated above): 20-40%
Lateral gradient along the structure: 3-7%
SLM Project, Helvetas, HELVETAS Swiss Intercooperation, Afghanistan
|1.||Construction of secondary and micro-irrigation canals||Spring|
Duration of establishment phase: 0.25 month(s)
|1.||Maintenance of canals||Spring/once per year|
Machinery/ tools: Pick axe and shovels
The presented costs were calculated on the basis of the exisiting local labour rate and the currency exchange rate which may vary from one year to another. For instance in 2010/11, 1 USD was 50 Afghani.
The cost of payment to the Mirab (Water distributor appointed by the land users) is not included. According to the land user, the Mirabs receive about 700 kg wheat/year from all the land users who use the main canal.
Labour is the most determinate factor affecting the costs. All the work is done manually.
- < 250毫米
- > 4,000毫米
Most rainfall is in May. According to provincial agriculture department, Bamyan centre receives about 230 mm rain a year
Thermal climate class: temperate. Winter temperatures can go below minus 20 degree C and maximum in summer up to 34 degree C
- 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.
- 非常深（> 120厘米）
Land users applying the Technology are mainly common / average land users
Difference in the involvement of women and men: Women are however involved in other agriculture works but at the plantation site, they are not involved at all. The land user has about 0.4 ha irrigated crop land used for potato and wheat cultivation on a rotation basis.
Population density: 10-50 persons/km2
Annual population growth: 2% - 3%
Off-farm income specification: The land user family is food secure from its own production for up to 6 months only. For food security for 12 months, they have to depend on other sources of off farm income. The agriculture land is not enough to meet all the family needs.
- < 0.5 公顷
- 0.5-1 公顷
- 1-2 公顷
- > 10,000公顷
For water distribution, there is a traditional system called as Mirab which is applied for the plantations as well. The land user applying the plantation/micro-irrigation technique have to participate in main irrigation canal repair and cleaning works. The land user also has to pay in kind or cash to the Mirab for his services.
Irrigation helps in Poplar establishment and growth
Important for reducing plant mortality
The area was degraded before
From sale of poplar trees but only in the long term
Irrigation needs more time and labour
Other land users see and learn
Fuel wood sufficiency
Lopped branches are used for fuel wood
contribution to human well-being
The technology contributes to increased household income in the long term and also towards increased production of fodder, fuel wood and timber.
Due to build of humus and ground cover
Due to plantations
due to increased soil moisture
habitat for birds
Due to plantations (indirect impact)
Due to plantations
Due to less sedimentation and runoff from the site
Stabilize the technology with grasses and reduce the slope of the channels so that it is less sensitive to increase in rainfall intensities.
The returns in the form of cash start coming after 10-12 years with this poplar variety following a selective felling and replanting approach.
100% of land user families have adopted the Technology without any external material support
80 land user families have adopted the Technology without any external material support
The total area under this plantation in the village is estimated to be 16 ha (80 jerib)
There is a small growing trend towards the adoption of the technology by communities and individuals in the area. Adoption depends on (and is hampered by) the availability of a reliable water source near the sites with potential for plantation and also about the land.
|The technology helps successful establishment of poplar trees and also natural grasses on sloping lands.|
|Micro-irrigation technology is important for the establishment and maintenance of poplar plantations. The technology is adapted for afforestation of sloping land.|
|The technology does not require much maintenance once the plantations are well established. A special attention need to be given to the secondary canals.|
|No external support for establishing or maintaining the technology.|
|The technology helps in improving the site's micro climate which leads to more plant and animal (bird) diversity.|
|There is no information available regarding the land user's view on the weaknesses of this technology.|
|The canals break at some weak points. Also the slopes of the micro channels is more at many places leading to some soil erosion.||Proper alignment of micro-irrigation canals.|
|Rill and gully erosion due to rapid and uncontrolled flow of excessive drainage in secondary canals.||Plant grasses with robust root system along the canals. Strengthen points where water spills from the micro-irrigation canals into the secondary canals with vegetative measures and sediment pits.|
|Due to small sizes of the channels, irrigation needs more time and labour.||Improvements in micro irrigation canals will reduce this problem considering. Interested organisations could carry out action research on how to improve this system by also incorporating efficient water use measures.|
|The technology can be applied only when there is a reliable source of running water.||Action research on soil and water conservation techniques for plantations in areas where there is no easy access to irrigation water.|