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

Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)

Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

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

2.1 Short description of the Technology

Definition of the Technology:

Spate irrigation is a traditional water diversion and spreading technology.

2.2 Detailed description of the Technology

Description:

Spate irrigation has a long history in Eritrea and still forms the livelihood base for rural communities in arid lowlands of the country.

Purpose of the Technology: It is a traditional water diversion and spreading technique under which seasonal floods of short duration – springing from the rainfall-rich highlands – are diverted from ephemeral rivers (wadis) to irrigate cascades of leveled and bunded fields in the coastal plains.

Establishment / maintenance activities and inputs: The diversion structures include the following elements: (1) the ‘agim’, a temporary 3-4 m high river diversion structure on the low-flow side of the wadi, made from brushwood, tree trunks, earth, stones and/or boulders, erected to divert a large part of the flow during a spate flow to adjacent agricultural fields; (2) a primary, and several secondary, distribution canals; unlined, bordered by earthen embankments; convey and spread the floodwater to the irrigable fields; (3) the fields, rectangular shaped, of about 1–2 ha, separated by earthen bunds. Floodwater is distributed from field to field: when a field is completely flooded (to a depth of about 0.5 m), water is conveyed to the immediate downstream field by breaching one of the bunds. This process continues until all the water is used up. Arable fields need to be flooded several times. The water soaks deep into the soil profile (up to 2.4 m) and provides moisture sufficient for two or even three harvests: crop growth is entirely dependent on the residual soil moisture. The main crop grown is sorghum; maize is the next most important. Sedimentation is as important as water management: With each flood, soil is built up by depositing rich sediment on the fields. Due to the force of the floods, the diversion structures are frequently damaged and/or washed away. Reconstruction and maintenance are labour-intensive and require collective community action.

Natural / human environment: Elaborate local regulations, organization and cooperation at the community level are prerequisites for successful management of spate irrigation systems.

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:

Eritrea

Region/ State/ Province:

Sheeb area, Eastern lowlands

Further specification of location:

Wadi Laba

Specify the spread of the Technology:

• evenly spread over an area

If the Technology is evenly spread over an area, specify area covered (in km2):

160.0

Comments:

Total area covered by the SLM Technology is 160 km2.

Current spate irrigation area in Eritrea is 16’000 hectares. Potential area is estimated at 60’000–90’000 hectares.

Map

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2.6 Date of implementation

If precise year is not known, indicate approximate date:

• more than 50 years ago (traditional)

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• as part of a traditional system (> 50 years)

Comments (type of project, etc.):

Spate irrigation is an indigenous technology, originally introduced from Yemen

3.1 Main purpose(s) of the Technology

• improve production
• reduce, prevent, restore land degradation

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

Cropland

• Annual cropping

Annual cropping - Specify crops:

• cereals - maize
• cereals - sorghum

Comments:

Livestock is grazing on crop residues

3.4 Water supply

Comments:

Water supply: post-flooding

3.5 SLM group to which the Technology belongs

• irrigation management (incl. water supply, drainage)
• surface water management (spring, river, lakes, sea)

3.6 SLM measures comprising the Technology

structural measures

• S3: Graded ditches, channels, waterways

Comments:

Main measures: structural measures

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

Cross section of an agim (top left); Components of a traditional spate irrigation system: (1) agim; (2) main distribution canal; (3) irrigated fields; (4) earthen embankments. Arrows indicate the water flow

Technical knowledge required for field staff / advisors: high

Technical knowledge required for land users: high

Main technical functions: control of concentrated runoff: drain / divert, increase of infiltration, water harvesting / increase water supply, water spreading

Diversion ditch/ drainage
Depth of ditches/pits/dams (m): 4.00

Construction material (earth): earth

Construction material (stone): stones

Construction material (wood): brushwood, tree trunks

Author:

Mats Gurtner, Center for Development and Environment, University of Bern

4.3 Establishment activities

4.4 Costs and inputs needed for establishment

4.5 Maintenance/ recurrent activities

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

Comments:

Machinery/ tools: scouring and tillage implements, shovels

The costs were calculated per unit = 10 m long agim (1 m high, 3 m wide), constructed with mixed material (stones, earth, brushwood)

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

Data on labour inputs for construction/maintenance of canals and field bunds are not included, therefore not included in the tables above. Costs for agim reconstruction are 40% of establishment. Total maintenance costs depend on the number of reconstructions during normal spate season (2-4 times). The yearly cost (establishment and maintenance) reaches US$ 60-156.

5.1 Climate

5.2 Topography

Comments and further specifications on topography:

Altitudinal zone: 101-500 m a.s.l. (200 m.a.s.l.)

5.3 Soils

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 is medium (loam to silt loams)
Soil fertility is very high (alluvial silts formed by annual sedimentation)
Soil drainage/infiltration is good

5.4 Water availability and quality

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Land users applying the Technology are mainly disadvantaged land users

Difference in the involvement of women and men: water management carried out communally, crop management individually

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

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

Land ownership:

• state

Land use rights:

• individual

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Income and costs

Socio-cultural impacts

Ecological impacts

Water cycle/ runoff

Soil

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

Climate-related extremes (disasters)

Meteorological disasters

Climatological disasters

Hydrological disasters

Comments:

The technology is tolerant to climatic extremes (adapted to unpredictable heavy floods)

6.4 Cost-benefit analysis

Comments:

no data

6.5 Adoption of the Technology

Comments:

There is a strong trend towards spontaneous adoption of the Technology

Comments on adoption trend: Spontaneous spread takes place throughout the lowlands. Current spate irrigation area in Eritrea is 16’000 hectares. Potential area is estimated at 60’000–90’000 hectares.

6.7 Strengths/ advantages/ opportunities of the Technology

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

7.2 References to available publications

Title, author, year, ISBN:

Abraham Mehari H, Van Steenbergen F, Verheijen O, Van Aarst S:Spate Irrigation, Livelihood Improvement and Adaptation to Climate Variability and Change

Title, author, year, ISBN:

Mehretab Tesfai Stroosnijder L:The Eritrean spate irrigation system

Title, author, year, ISBN:

Berhane Haile G, Van Steenbergen F: Agricultural Water Management in Ephemeral Rivers: Community Management in Spate Irrigation in Eritrea; in African Water Journal

7.3 Links to relevant online information

Title/ description:

Abraham Mehari, Depeweg, H, Schultz B (2005): Hydraulic Performance Evaluation of The Wadi Laba Spate Irrigation Systemin Eritrea, in Irrigation and Drainage. 54: 389–406

URL:

www.interscience.wiley.com

Title/ description:

Berhane Haile G: Community Spate Irrigation in Bada, Eritrea n Mehretab Tesfai, Stroosnijder L (2000): The Eritrean spate irrigation system

URL:

linkinghub.elsevier.com/retrieve/pii/S0378377400001153