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 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:

Yes

1.4 Declaration on sustainability of the described Technology

Is the Technology described here problematic with regard to land degradation, so that it cannot be declared a sustainable land management technology?

No

2.1 Short description of the Technology

Definition of the Technology:

The role of masonry micro-dams is to raise the level of the water table so as to supply wells and create water reserves for off-season farming activities.

2.2 Detailed description of the Technology

Description:

A masonry micro-dam is a structure built of dressed stone pointed with cement mortar. The width of the crest is 0.75 metres. The length generally ranges from 100 to 200 metres depending on the site. The height varies between two and four metres. The dam creates a water reservoir upstream covering an area of around 5 to 15 hectares. Micro-dams are equipped with buttresses and a stilling basin. Each dam has a sluice fitted with a stoplog gate for draining away sediment during the first rains of the season and to regulate water levels. The use of stoplog gates is recommended instead of sluice gates, as the latter are more technically sophisticated and require more maintenance. Farming is carried out upstream and downstream in the rainy season and off-season.

The dam increases the amount of available surface water during the rainy season and groundwater during the off-season. This results in increasing the farmland area as well as yields and production. A second growing season is made possible. Its effect on the water table depends on the depth of the scheme’s foundations: the deeper the foundations, the greater the recharge of ground water. During the rainy season, the lands are used for rice growing. The wells used for irrigating market gardens are fed from the water table, meaning vegetables can be grown off-season. The water is also used for watering livestock, fish farming and, sometimes, domestic purposes.

Implementation steps: An information and awareness-raising workshop is organised on the IPRO-DB approach at the commune level, involving the villages affected by the project. A general meeting is held to secure the support of the whole village for the development request. The village chief and commune mayor sign off the request. The project team carries out a scoping study and socio-economic surveys. If the outcomes of the scoping study phase and socio-economic surveys are positive, the terms of reference are drawn up for working with consultancies. Consultancies are selected through tender processes to carry out the technical studies and create the invitation to tender document. The project team monitors the consultancies’ delivery of the technical studies. The village pays its financial contribution towards the project. The management committee is set up and organisational and technical training is provided to beneficiaries. Exchange visits are organised with villages that have experience in installing these schemes. The project team, village, mayor and company sign the memorandum of understanding. Stone breaking gets underway. Landowners sign the transfer deeds for the site. The invitation to tender for the building works is published and the contractor selected. The invitation to tender for works supervision is published and the supervisory consultancy selected. The building contractor and supervisory consultancy are introduced to the village and begin the building work. Local labour is employed in building the scheme. Partial acceptance of the building works (for example, foundations, wall, buttresses, stilling basin, gabion reinforcements, etc.) is granted. The project team monitors the building works. Payment for activities is made on a unit-price basis. Interim acceptance is granted. Final acceptance is granted after one year.
A management committee takes charge of opening and closing stoplog gates, organises the maintenance of the scheme and institutes additional measures to protect the scheme (gabions, stone bunds, etc.). It collects and manages maintenance fees, ensures the committee’s rules of procedure are adhered to and organises meetings of local producers. With minimum levels of maintenance, a scheme will remain functional for at least 20 years.

Around 60 masonry dams have been built or rehabilitated in the Bandiagara and Bélédougou areas.

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

2.6 Date of implementation

If precise year is not known, indicate approximate date:

• 10-50 years ago

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• through projects/ external interventions

Comments (type of project, etc.):

This type of dam has been built since the 1990s, by IPRO-DB

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

Land use mixed within the same land unit:

Yes

Specify mixed land use (crops/ grazing/ trees):

• Agro-silvopastoralism

Cropland

• Annual cropping

Number of growing seasons per year:

• 1

Specify:

Longest growing period in days: 120, Longest growing period from month to month: August-November

Waterways, waterbodies, wetlands

• Ponds, dams

Comments:

Major land use problems (compiler’s opinion): lack of surface water and groundwater
Livestock density: 1-10 LU /km2

3.4 Water supply

Water supply for the land on which the Technology is applied:

• mixed rainfed-irrigated

3.5 SLM group to which the Technology belongs

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

3.6 SLM measures comprising the Technology

structural measures

• S5: Dams, pans, ponds

3.7 Main types of land degradation addressed by the Technology

biological degradation

• Bc: reduction of vegetation cover

water degradation

• Ha: aridification
• Hg: change in groundwater/aquifer level

Comments:

Main causes of degradation: over abstraction / excessive withdrawal of water (for irrigation, industry, etc.)

3.8 Prevention, reduction, or restoration of land degradation

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

• prevent land degradation
• restore/ rehabilitate severely degraded land

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

A masonry micro-dam is a structure built of dressed stone pointed with cement mortar. The width
of the crest is 0.75 metres. The length generally ranges from 100 to 200 metres depending on
the site. The height varies between two and four metres. The dam creates a water reservoir
upstream covering an area of around 5 to 15 hectares. Micro-dams are equipped with buttresses
and a stilling basin. Each dam has a sluice fitted with a stoplog gate for draining away sediment
during the first rains of the season and to regulate water levels.

Technical knowledge required for field staff / advisors: high
Technical knowledge required for land users: low
Main technical functions: increase of infiltration, increase / maintain water stored in soil, increase of groundwater level / recharge of groundwater, water harvesting / increase water supply, water spreading

Dam/ pan/ pond
Height of bunds/banks/others (m): 2-4
Width of bunds/banks/others (m): 0.75
Length of bunds/banks/others (m): 100-200

Author:

IPRO-DB

4.2 General information regarding the calculation of inputs and costs

other/ national currency (specify):

CFA Franc

If relevant, indicate exchange rate from USD to local currency (e.g. 1 USD = 79.9 Brazilian Real): 1 USD =:

517.0

4.3 Establishment activities

4.4 Costs and inputs needed for establishment

4.5 Maintenance/ recurrent activities

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

Each dam costs between 100 and 140 million CFA francs (195'583-273'817 Dollar). Costs are reduced as a result of the availability of local materials and the fact that local masons and contractors are well versed in this type of technology.

5.1 Climate

5.2 Topography

5.3 Soils

5.4 Water availability and quality

5.5 Biodiversity

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Population density: < 10 persons/km2
Annual population growth: 2% - 3%
10% of the land users are rich.
50% of the land users are average wealthy.
30% of the land users are poor.
10% of the land users are very poor.

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

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

Comments:

The irrigated land is allocated by the chief

5.9 Access to services and infrastructure

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

Other climate-related consequences

Other climate-related consequences

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?

6.7 Strengths/ advantages/ opportunities of the Technology

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

7.1 Methods/ sources of information

7.2 References to available publications

Title, author, year, ISBN:

IPRO-DB (2007): Fiches techniques des barrages individuels. [Data sheet on individual dams]

Title, author, year, ISBN:

Manual of Good Practices in Small Scale Irrigation in the Sahel. Experiences from Mali. Published by GIZ in 2014.

Available from where? Costs?

http://star-www.giz.de/starweb/giz/pub/servlet.starweb

Title, author, year, ISBN:

IPRO-DB: Module de formation pour la préparation des aménagements [Training module on preparing schemes] (avail-able in French and Bambara)

Title, author, year, ISBN:

IPRO-DB: Module de formation sur l’entretien des ouvrages [Training module on scheme maintenance] (available in French and Bambara)

Title, author, year, ISBN:

IPRO-DB: Approches du projet de l’irrigation de proximité au Pays Dogon et dans le Bélédougou [Small-scale irrigation project approaches in Dogon Country and in the Bélédougou region], (O. Fritz, Technical Assistant, GIZ, December 2011)