1.2 Detalles de contacto de las personas de referencia e instituciones involucradas en la evaluación y la documentación de la Tecnología

Nombre del proyecto que financió la documentación/ evaluación de la Tecnología (si fuera relevante)

Manual of Good Practices in Small Scale Irrigation in the Sahel (GIZ )

Nombre de la(s) institución(es) que facilitaron la documentación/ evaluación de la Tecnología (si fuera relevante)

Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH (GIZ) - Alemania

1.3 Condiciones referidas al uso de datos documentados mediante WOCAT

¿Cuándo se compilaron los datos (en el campo)?

01/07/2012

El compilador y la/s persona(s) de referencia claves aceptan las condiciones acerca del uso de los datos documentados mediante WOCAT:

Sí

1.4 Declaración de la sostenibilidad de la Tecnología descrita

¿La Tecnología aquí descrita resulta problemática en relación a la degradación de la tierra, de tal forma que no puede considerársela una tecnología sostenible para el manejo de la tierra?

No

2.1 Breve descripción de la Tecnología

Definición de la Tecnología:

Small-scale dams are moderately-sized barriers built across valley bottoms to retain water from permanent watercourses or seasonal flows.

2.2 Descripción detallada de la Tecnología

Descripción:

They can range in length from 100 to 200 m, and the dam wall is usually between 2 and 4 m high. Small-scale dams impound permanent or seasonal water behind them, covering areas from 5 to 15 hectares. They are built with buttresses and a stilling basin. Depending on local conditions, the dam wall can be made of quarry stone joined with mortar or concrete. The dikes are made of earth and can be reinforced with stones. Some such structures are built as bridge dams, providing a means of crossing the valley. The effect on the water table depends on the depth at which the dam is anchored. The deeper the foundation, the more groundwater is retained. Sometimes, they are fitted with geomembranes which extend down deeper to retain more groundwater.

In the rainy season, water gradually accumulates behind the dike, increasing the availability of surface water during the rainy season and groundwater in the dry season. The land is farmed upstream and downstream both in the rainy season and the dry season. During the rainy season, rice is grown, and the areas around the body of water are used for other crops (flood-recession cropping). Dams increase the area of farmable land, yields and production. The water is also used for livestock, for fish farming and sometimes for household needs. The recharged water table feeds market garden wells, enabling farmers to grow vegetables in the dry season and permitting two or three crop harvests a year which increases the availability of food, providing income for farmers and guaranteeing work all year round. This improves the stability of local communities, increases their income and raises their standard of living.

Sustainable operation and management depend directly on the participatory approach. At the planning stage, the condition of the valley upstream and downstream and all user groups must be taken into account. The question of land tenure, in particular, must be settled before construction begins. It must be determined who the owner of the bottomlands is, who will be entitled to use them once the dam has been constructed, what uses will be permitted and under what conditions. The question of project ownership and upkeep must also be clarified. Today, the role of project owner is normally assigned to the commune authorities, although management of the dam is often delegated to a management committee. In order to avoid conflicts, it is essential to take into account all the user groups, livestock keepers in particular. Watering corridors must be established to prevent animals from damaging the crops. In order to maximise the value of the investment, well-organised management committees must be set up to ensure efficient crop production and oversee maintenance work. A management committee controls the opening and closing of the gates. It organises the maintenance of the structure and the implementation of any additional measures necessary to protect the gabion structures and stone bunds. It also collects and manages funds for the maintenance of the dam and organises meetings of farmers. In dry periods, it is important to manage water resources in such a way that downstream areas have enough water. When a series of dams are built on the same watercourse, an inter-dam committee may be required to manage the distribution of water and avoid conflicts between the users of the different dams.
Well-constructed small-scale dams last at least 50 years with a certain amount of upkeep. A high standard of technical planning and construction is required for small-scale dams to avoid subsequent damage. Depending on the natural characteristics of the watershed, small-scale dams may require additional SWC/SPR measures upstream to protect them from siltation.

These small-scale dams are suitable for use in narrower valleys, as a considerable volume of water can be impounded with a relatively short structure. They are not as well suited to wide, gently sloping valleys, as very long dikes are required and this increases the cost.

2.3 Fotografías de la Tecnología

2.5 País/ región/ lugares donde la Tecnología fue aplicada y que se hallan comprendidos por esta evaluación

2.6 Fecha de la implementación

Si no se conoce el año preciso, indique la fecha aproximada:

• 10-50 años atrás

2.7 Introducción de la Tecnología

Especifique cómo se introdujo la Tecnología:

• mediante proyectos/ intervenciones externas

Comentarios (tipo de proyecto, etc.):

developed, implemented and disseminated as part of projects and programmes undertaken from the 1980s onwards to combat desertification and improve natural resource management. Implemented by GIZ (German Federal Enterprise for International Cooperation), and the project to rehabilitate dams and tracks (PRBP) and the Mali north programme (PMN)

3.1 Propósito(s) principal(es) de la Tecnología MST

• mejorar la producción

3.2 Tipo(s) actuales de uso de la tierra donde se aplica la Tecnología

Comentarios:

Major land use problems (compiler’s opinion): lack of irrigation water, surface water, soil erosion by water and wind
Constraints of common grazing land
Constraints of forested government-owned land or commons

3.3 Información adicional sobre el uso de tierras

Provisión de agua para la tierra donde se aplica la Tecnología:

• mixta de secano – irrigada

Número de temporadas de cultivo por año:

• 1

Especifique:

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

3.4 Grupo MST al que pertenece la Tecnología

• Manejo de irrigación: (incl. provisión de agua, invernaderos)
• diversión y drenaje de agua
• manejo de agua superficial (manantial, río, lagos, mar):

3.5 Difusión de la Tecnología

Especifique la difusión de la Tecnología:

• distribuida parejamente sobre un área

Si la tecnología se halla difundida homogéneamente en un área, indique el área aproximada que cubre:

• 0.1-1 km2

Comentarios:

Small-scale dams impound permanent or seasonal water behind them, covering areas from 5 to 15 hectares

3.6 Medidas MST que componen la Tecnología

3.7 Principales tipos de degradación del suelo encarados con la Tecnología

Comentarios:

Main causes of degradation: crop management (annual, perennial, tree/shrub), floods, droughts, population pressure, land tenure

3.8 Prevención, reducción o restauración de la degradación del suelo

Especifique la meta de la Tecnología con relación a la degradación de la tierra:

• prevenir la degradación del suelo
• restaurar/ rehabilitar tierra severamente degradada

4.1 Dibujo técnico de la Tecnología

4.2 Especificaciones técnicas/ explicaciones del dibujo técnico

They can range in length from 100 to 200 m, and the dam wall is usually between 2 and 4 m high.

Technical knowledge required for field staff / advisors: high
Technical knowledge required for land users: low
Main technical functions: control of dispersed runoff: retain / trap, control of concentrated runoff: retain / trap, increase of infiltration, increase / maintain water stored in soil, increase of groundwater level / recharge of groundwater, water harvesting / increase water supply
Secondary technical functions: increase in organic matter, increase in nutrient availability (supply, recycling,…), sediment retention / trapping, sediment harvesting, increase of biomass (quantity), promotion of vegetation species and varieties (quality, eg palatable fodder)

Dam/ pan/ pond
Depth of ditches/pits/dams (m): 2-4
Length of ditches/pits/dams (m): 100-200

4.4 Actividades de establecimiento

	Actividad	Tipo de medida	Momento
1.	At the planning stage, the condition of the valley upstream and downstream and all user groups must be taken into account. The question of land tenure must be settled before construction begins. The question of project ownership and upkeep must also be clarified.	Estructurales
2.	In order to avoid conflicts, it is essential to take into account all the user groups, livestock keepers in particular	Estructurales
3.	Construction of dam	Estructurales
4.	Watering corridors must be established to prevent animals from damaging the crops	Estructurales
5.	well-organised management committees must be set up to ensure efficient crop production and oversee maintenance work	Estructurales

4.6 Actividades de establecimiento/ recurrentes

	Actividad	Tipo de medida	Momento/ frequencia
1.	A management committee controls the opening and closing of the gates. It organises the maintenance of the structure and the implementation of any additional measures necessary to protect the gabion structures and stone bunds. It also collects and manages funds for the maintenance of the dam and organises meetings of farmers	Estructurales
2.	Depending on the natural characteristics of the watershed, small-scale dams may require additional SWC/SPR measures upstream to protect them from siltation.	Estructurales

4.8 Factores más determinantes que afectan los costos:

Describa los factores más determinantes que afectan los costos:

The cost of small-scale dams varies greatly depending on the physical characteristics of the site, the size of the structure and the local availability of materials. In Dogon country, in Mali, the PDRT project constructed dams with cyclopean concrete costing an average of around 20 million CFA francs and between 3 and 5 million CFA francs per hectare. The internal rate of return of the dams built averaged 17% (Nill & Kobilke, 2002). Larger dams built in the Beledougou area cost 100-140 million CFA francs. Helvetas Swiss Intercooperation reports costs of around 20 million CFA francs for areas of 10-80 hectares (PASSIP, 2012).

5.1 Clima

5.2 Topografía

5.3 Suelos

5.4 Disponibilidad y calidad de agua

5.5 Biodiversidad

5.6 Las características de los usuarios de la tierra que aplican la Tecnología

Indique otras características relevantes de los usuarios de las tierras:

Population density: 10-50 persons/km2
Annual population growth: 3% - 4% (mostly poor households below poverty line).
Off-farm income specification: men migrate temporarily or permanently to cities for off-farm income

5.7 Área promedio de la tierra que pertenece a o es arrendada por usuarios de tierra que aplican la Tecnología

5.8 Tenencia de tierra, uso de tierra y derechos de uso de agua

Tenencia de tierra:

• estado

Derechos de uso de tierra:

• comunitarios (organizado)

Derechos de uso de agua:

• comunitarios (organizado)

Comentarios:

traditional land use rights on fields, communal land on pasture and forest land

5.9 Acceso a servicios e infraestructura

6.1 Impactos in situ demostrados por la Tecnología

Impactos socioeconómicos

Producción

Disponibilidad y calidad de agua

Impactos socioculturales

Impactos ecológicos

Ciclo de agua/ escurrimiento de sedimento

Suelo

Biodiversidad: vegetación, animales

6.2 Impactos fuera del sitio demostrados por la Tecnología

6.3 Exposición y sensibilidad de la Tecnología al cambio climático gradual y a extremos relacionados al clima/ desastres (desde la percepción de los usuarios de tierras)

Cambio climático gradual

Cambio climático gradual

	Estación	tipo de cambios climáticos/ climas extremos	¿Cómo es que la tecnología soporta esto?
temperatura anual		incrementó	bien

Extremos (desastres) relacionados al clima

Desastres climatológicos:

	¿Cómo es que la tecnología soporta esto?
tormenta de lluvia local	bien
tormenta de viento	bien

Desastres climatológicos

	¿Cómo es que la tecnología soporta esto?
sequía	bien

Desastres hidrológicos

	¿Cómo es que la tecnología soporta esto?
inundación general (río)	bien

Otras consecuencias relacionadas al clima

Otras consecuencias relacionadas al clima

	¿Cómo es que la tecnología soporta esto?
periodo reducido de crecimiento	bien

6.4 Análisis costo-beneficio

¿Cómo se comparan los beneficios con los costos de establecimiento (desde la perspectiva de los usuarios de tierra)?

¿Cómo se comparan los beneficios con los costos de mantenimiento/ recurrentes (desde la perspectiva de los usuarios de tierra)?

6.7 Fuerzas/ ventajas/ oportunidades de la Tecnología

Fuerzas/ ventajas/ oportunidades desde la perspectiva del compilador o de otra persona de referencia clave
The small-scale dams create water reserves. When there is not enough rain or during dry spells in the rainy season, the dams retain enough water for crops throughout their growth cycle. If rain-fed crops fail, production in the valley bottoms can mitigate these losses. In wet years, the dams regulate the flow of water, preventing heavy floodwaters from causing damage to land downstream.
The water impounded by small-scale dams makes it possible to farm a much larger area in the valley bottoms and ensures better yields in the rainy season and also in the off-season. The production of food staples and market garden output increases significantly. More intense production ensures employment all year round, which improves the stability of local communities, increases their income and raises their standard of living.
In the dry season, the recharged water table makes a second and even third crop harvest possible, increasing the availability of food, providing income for farmers and guaranteeing work all year round.
Replenished water tables not only improve crop output, they also reduce the time and effort that women devote to fetching water and make it easier to water livestock.

6.8 Debilidades/ desventajas/ riesgos de la Tecnología y formas de sobreponerse a ellos

Debilidades/ desventajas/ riesgos desde la perspectiva del compilador o de otra persona de referencia clave	¿Cómo sobreponerse a ellas?
A high standard of technical planning and construction is required for small-scale dams to avoid subsequent damage.	In order to maximise the value of the investment, well-organised management committees must be set up to ensure efficient crop production and oversee maintenance work.

7.1 Métodos/ fuentes de información

7.2 Vínculos a las publicaciones disponibles

Título, autor, año, ISBN:

Good Practices in Soil and Water Conservation. A contribution to adaptation and farmers´ resilience towards climate change in the Sahel. Published by GIZ in 2012.

¿Dónde se halla disponible? ¿Costo?

http://agriwaterpedia.info/wiki/Main_Page