1.2 Coordonnées des personnes-ressources et des institutions impliquées dans l'évaluation et la documentation de la Technologie

Nom du ou des institutions qui ont facilité la documentation/ l'évaluation de la Technologie (si pertinent)

Haramaya University (HU) - Ethiopie

1.3 Conditions relatives à l'utilisation par WOCAT des données documentées

Quand les données ont-elles été compilées (sur le terrain)?

02/05/2011

Le compilateur et la(les) personne(s) ressource(s) acceptent les conditions relatives à l'utilisation par WOCAT des données documentées:

Oui

2.1 Courte description de la Technologie

Définition de la Technologie:

Stone wall check dams are built across a gully to collect alluvial soil and hinder further gully erosion.

2.2 Description détaillée de la Technologie

Description:

During the 1980s stone walls and terraces were introduced in Ethiopia in order to combat soil erosion. The technology of stone walls or terraces is used to stabilize hills or to refill gullies also in Bati, Ethiopia. Stone walls can form a very strong check dam to rehabilitate gullies even several meters deep.

Purpose of the Technology: Although stone walls can be used for different purposes, this case study is focusing on stone walls used to combat gully erosion. Farmers in the Bati region often use stone walls to rehabilitate gullies if the material is easily accessible, otherwise they may search for alternatives.

Establishment / maintenance activities and inputs: Following procedure is undertaken to build a stone wall check dam: After breaking the stones in the source-area they are transported to the target-area either by hand, by camels or by donkeys, depending on the distance. After digging a foundation for the wall of approximately 30 cm depth, the gap between two rows of big stones 1 m apart is filled up with smaller stones and gravel. These actions are repeated until the desired height and width of the wall are reached

Natural / human environment: The case study site, Bati, lays in an semiarid climatic zone on 1600 m a.s.l. Rainfalls are erratic and the rain sum per year is between 500-1000 mm. The landscape is very hilly with rather steep slopes. As almost in all Ethiopia, the area has a high population density and growth. The agricultural sector is very dominant and lead by a lot of small scale farming with a lot of livestock and small plots of cropland.

2.3 Photos de la Technologie

2.5 Pays/ région/ lieux où la Technologie a été appliquée et qui sont couverts par cette évaluation

2.6 Date de mise en œuvre de la Technologie

Si l'année précise est inconnue, indiquez la date approximative: :

• il y a entre 10-50 ans

2.7 Introduction de la Technologie

Spécifiez comment la Technologie a été introduite: :

• par le biais de projets/ d'interventions extérieures

Commentaires (type de projet, etc.) :

Soil and water conservation measures, including stone wall check dams, were mainly introduced to land users during the 1980s by the government. Sometimes the technology is not adequately performed though. In recent years the local Agricultural Office is teaching farmers how to correctly build soil and water conservation measures not only on a technology basis but to take care of an integrated watershed management.

3.1 Principal(aux) objectif(s) de la Technologie

• réduire, prévenir, restaurer les terres dégradées

3.2 Type(s) actuel(s) d'utilisation des terres, là où la Technologie est appliquée

Commentaires:

Major land use problems (compiler’s opinion): Deforestation, overgrazing, cultivation of erosion-sensitive areas or steep slopes.

Major land use problems (land users’ perception): Too much soil loss and land degradation, no vegetation cover and poor soil moisture.

Grazingland comments: Livestock is not fenced in. Children herd the animals and watch out that they do not browse through crop fields. In off-farming season crop residues are collected from the field and stored next to the field. Animals are allowed to eat the still remaining residues on the field. After that, the animals are fed by the collected crop residues.

Livestock is grazing on crop residues

Type of grazing system comments: Livestock is not fenced in. Children herd the animals and watch out that they do not browse through crop fields. In off-farming season crop residues are collected from the field and stored next to the field. Animals are allowed to eat the still remaining residues on the field. After that, the animals are fed by the collected crop residues.

3.3 Informations complémentaires sur l'utilisation des terres

Approvisionnement en eau des terres sur lesquelles est appliquée la Technologie:

• mixte: pluvial-irrigué

Commentaires:

Water supply: Also rainfed

Précisez:

Longest growing period in days: 90 Longest growing period from month to month: June until September

Densité d'élevage/ chargement (si pertinent):

> 100 LU /km2

3.4 Groupe de GDT auquel appartient la Technologie

• mesures en travers de la pente

3.5 Diffusion de la Technologie

Commentaires:

Total area covered by the SLM Technology is 0.6 m2.

Size of the case study watershed.

3.6 Mesures de GDT constituant la Technologie

Commentaires:

Main measures: structural measures

3.7 Principaux types de dégradation des terres traités par la Technologie

Commentaires:

Main type of degradation addressed: Wg: gully erosion / gullying

Secondary types of degradation addressed: Wt: loss of topsoil / surface erosion

Main causes of degradation: deforestation / removal of natural vegetation (incl. forest fires) (Deforestation for the past 30 years.), over-exploitation of vegetation for domestic use (Wood collection for cooking and construction.), overgrazing (50% of the watershed area are cultivated - big grazing pressure on remaining land), other human induced causes (specify) (Cultivation of very steep slopes.), change of seasonal rainfall (Erratic rainfall.), Heavy / extreme rainfall (intensity/amounts) (If there is rain, it is intensive.), population pressure (High population pressure.), poverty / wealth (Poor facilities.)

Secondary causes of degradation: soil management (Poor soil management practices and lack of awareness.), crop management (annual, perennial, tree/shrub) (Annual cropping.), droughts (The research area is considered rather dry.), land tenure (If the land is rented, it is poorly managed.), inputs and infrastructure: (roads, markets, distribution of water points, other, …) (Poor access to fertilizer. Bad infrastructures.), education, access to knowledge and support services (Lack of awareness for soil degradation.), Low productivity of the land (As a consequence seeking for new/larger areas to increase production.)

3.8 Prévention, réduction de la dégradation ou réhabilitation des terres dégradées

Spécifiez l'objectif de la Technologie au regard de la dégradation des terres:

• réduire la dégradation des terres
• restaurer/ réhabiliter des terres sévèrement dégradées

Commentaires:

Secondary goals: mitigation / reduction of land degradation

4.1 Dessin technique de la Technologie

4.2 Spécification/ explications techniques du dessin technique

Stone wall check dams as they can be found in the region of Bati. The approximately 1 m wide gap between two rows of larger stones is filled up with small stones or gravel. This is done for every new level of the wall until the wall reaches its final height. The first row of stones is placed in the top 30 cm of the ground and on each side the dam is entering the hill to some extent. After a wall has silted up, the height is increased by other rows of stones until desired dimension is reached. Walls up to 5 m can be found in the case study site.

Location: South-West of Bati. Bati Woreda, Amhara Region, Ethiopia

Date: 26.04.2011

Technical knowledge required for field staff / advisors: moderate (To teach the farmers how to perform an integrated watershed management.)

Technical knowledge required for land users: high (To build a robust check dam there is a lot of knowledge needed.)

Main technical functions: control of concentrated runoff: retain / trap, control of concentrated runoff: impede / retard, reduction of slope angle, reduction of slope length, increase / maintain water stored in soil, sediment retention / trapping, sediment harvesting

Secondary technical functions: water harvesting / increase water supply, improvement of water quality, buffering / filtering water

Retention/infiltration ditch/pit, sediment/sand trap
Depth of ditches/pits/dams (m): 6
Width of ditches/pits/dams (m): 10
Length of ditches/pits/dams (m): 1

If the original slope has changed as a result of the Technology, the slope today is: 0%

4.3 Informations générales sur le calcul des intrants et des coûts

autre/ monnaie nationale (précisez):

Ethiopian Birr

Indiquer le taux de change du dollars en monnaie locale (si pertinent): 1 USD= :

16,82

4.4 Activités de mise en place/ d'établissement

	Activité	Type de mesures	Calendrier
1.	Preparation of the stones (500 person days needed).	Structurel	During dry season.
2.	Transportation of the stones (depending on the distance).	Structurel	During dry season.
3.	Digging a foundation of 30 cm depth (165 person days needed).	Structurel	During dry season.
4.	Building of the stone wall (500 person days needed).	Structurel	During dry season.

4.5 Coûts et intrants nécessaires à la mise en place

	Spécifiez les intrants	Unité	Quantité	Coûts par unité	Coût total par intrant	% des coût supporté par les exploitants des terres
Main d'œuvre	Labour	ha	1,0	1165,0	1165,0	50,0
Equipements	Tools	ha	1,0	5,0	5,0	100,0
Coût total de mise en place de la Technologie					1170,0

4.6 Activités d'entretien/ récurrentes

	Activité	Type de mesures	Calendrier/ fréquence
1.	Prepare the stones (250 person days needed).	Structurel	During dry season if needed.
2.	If dam is silted up, increasing the height by 0.5 m (250 person days needed)	Structurel	Every year in dry season.

4.7 Coûts et intrants nécessaires aux activités d'entretien/ récurrentes (par an)

	Spécifiez les intrants	Unité	Quantité	Coûts par unité	Coût total par intrant	% des coût supporté par les exploitants des terres
Main d'œuvre	Labour	ha	1,0	500,0	500,0	50,0
Equipements	Tools	ha	1,0	5,0	5,0	100,0
Coût total d'entretien de la Technologie					505,0

Commentaires:

Machinery/ tools: Shovel, digging hoe, iron rod.

Total costs of a hectare were calculated for a wall of 100 m length and 1 m of height every 20 m (500 m total wall) in the year 2011. Tool prices were estimated and labor costs were calculated with a daily wage of 1$.

4.8 Facteurs les plus importants affectant les coûts

Décrivez les facteurs les plus importants affectant les coûts :

Rough topology in the area, questionable availability of construction materials if they are not found nearby.

5.1 Climat

5.2 Topographie

Commentaires et précisions supplémentaires sur la topographie:

Altitudinal zone: 1501-2000 m a.s.l. (The study site is located at 1600m a.s.l.)
Landforms: Hill slopes (ranked 1) and valley floors (ranked 2)
Slopes on average: Hilly (ranked 1), rolling (ranked 2) and steep (ranked 3)

5.3 Sols

Si disponible, joignez une description complète du sol ou précisez les informations disponibles, par ex., type de sol, pH/ acidité du sol, capacité d'échange cationique, azote, salinité, etc.

Soil depth on average: Very shallow (ranked 1) and shallow (ranked 2)
Soil textur: Coarse/light (ranked 1) and medium (ranked 2)
Soil fertility is low
Soil drainage/infiltration is poor
Soil water storage capacity is medium

5.4 Disponibilité et qualité de l'eau

Commentaires et précisions supplémentaires sur la qualité et la quantité d'eau:

Ground water table: Unknown
Availability of surface water is poor/none (Only during rainy season)
Water quality (untreated): Poor drinking water (treatment required, mostly groundwater)

5.5 Biodiversité

Commentaires et précisions supplémentaires sur la biodiversité:

Relative to other parts of Ethiopia.

5.6 Caractéristiques des exploitants des terres appliquant la Technologie

Indiquez toute autre caractéristique pertinente des exploitants des terres:

Land users applying the Technology are mainly common / average land users
Population density: 100-200 persons/km2
Annual population growth: 6%
1% of the land users are rich (Adopt the most of SWC technologies).
19% of the land users are average wealthy.
89% of the land users are poor.
Off-farm income specification: Off-farm income has low importance.
Level of mechanization: Animal traction (Plowing by oxen, ranked 1) and manual labour (ranked 2)
Market orientation cropland: Subsistence
Market orientation grazing land: Goat/sheep are main meat source (in household or on market).

5.7 Superficie moyenne des terres détenues ou louées par les exploitants appliquant la Technologie

5.8 Propriété foncière, droits d’utilisation des terres et de l'eau

Propriété foncière:

• individu, avec titre de propriété

Droits d’utilisation de l’eau:

• accès libre (non organisé)

5.9 Accès aux services et aux infrastructures

6.1 Impacts sur site que la Technologie a montrés

Impacts socio-économiques

Production

Disponibilité et qualité de l'eau

Revenus et coûts

Impacts socioculturels

Impacts écologiques

Cycle de l'eau/ ruissellement

Sols

Biodiversité: végétale, animale

Réduction des risques de catastrophe et des risques climatiques

6.2 Impacts hors site que la Technologie a montrés

6.3 Exposition et sensibilité de la Technologie aux changements progressifs et aux évènements extrêmes/catastrophes liés au climat (telles que perçues par les exploitants des terres)

Changements climatiques progressifs

Changements climatiques progressifs

	Saison	Type de changements/ extrêmes climatiques	Comment la Technologie fait-elle face à cela?
températures annuelles		augmente	bien

Extrêmes climatiques (catastrophes)

Catastrophes météorologiques

	Comment la Technologie fait-elle face à cela?
pluie torrentielle locale	bien
tempête de vent locale	bien

Catastrophes climatiques

	Comment la Technologie fait-elle face à cela?
sécheresse	bien

Catastrophes hydrologiques

	Comment la Technologie fait-elle face à cela?
inondation générale (rivière)	bien

Autres conséquences liées au climat

Autres conséquences liées au climat

	Comment la Technologie fait-elle face à cela?
réduction de la période de croissance	bien

6.4 Analyse coûts-bénéfices

Quels sont les bénéfices comparativement aux coûts de mise en place (du point de vue des exploitants des terres)?

Quels sont les bénéfices comparativement aux coûts d'entretien récurrents (du point de vue des exploitants des terres)?

Commentaires:

Big labour input for establishment. Also maintenance needs some work every year. But also high benefit by additional farming land gained due to the check dams.

6.5 Adoption de la Technologie

Commentaires:

100% of land user families have adopted the Technology with external material support

Comments on acceptance with external material support: In the past 6 years the local Agricultural Office has supported farmers to treat their watersheds with SWC technologies based on a food for work programme. Today farmers build the structures on their own but seek support.

There is a moderate trend towards spontaneous adoption of the Technology

Comments on adoption trend: Most of the farmers build SWC technologies (includin stone check dams in gullies) because of the food for work programme

6.7 Points forts/ avantages/ possibilités de la Technologie

Points forts/ avantages/ possibilités du point de vue de l'exploitant des terres
The stone check dams are conserving soil and moisture. How can they be sustained / enhanced? Maintain the dams.
Due to alluvial soil there is additional farming land and therefore increased productivity. How can they be sustained / enhanced? Take care of the walls as well of the surrounding area and the whole watershed.

Points forts/ avantages/ possibilités du point de vue du compilateur ou d'une autre personne ressource clé
Stone check dams are a quite durable structure. How can they be sustained / enhanced? Stability could be enhanced by additional technologies e.g. similar as gabbions or planting of trees/shrubs in front of the wall to reduce collapsing possibility.
The structure collects alluvial soil which can be plowed and used as new farming fields. How can they be sustained / enhanced? Structure maintenance is important. If the dam fails, the field is washed out as well.
The technology is widely used around the world (perhaps with local adaptations) and is therefore well documented. How can they be sustained / enhanced? Keep on with documentation and monitoring of limitations and potentials of stone check dams around the world.

6.8 Faiblesses/ inconvénients/ risques de la Technologie et moyens de les surmonter

Faiblesses/ inconvénients/ risques du point de vue de l’exploitant des terres	Comment peuvent-ils être surmontés?
The Land users could not tell any disadvantages of the technology.	Could be an indicator that there is enough spare time to build and maintain structures during off-farming season.

Faiblesses/ inconvénients/ risques du point de vue du compilateur ou d'une autre personne ressource clé	Comment peuvent-ils être surmontés?
Large labour input at establishment and during maintenance period.	Possibly by machinery but it is very expensive.
During time of establishment/maintenance there is no time for farming activites. These activities can therefore be seen as hidden costs.	Perhaps a "professional" team that takes care of check dams and is payed for it.

7.2 Références des publications disponibles

Titre, auteur, année, ISBN:

Bach S. (2012) Potentials and limitations of Jatropha curcas as a multipurpose crop for sustainable energy supply and soil and water conservation - a case study in Bati, Ethiopia, using the WOCAT approach. Unpublished master’s thesis, Centre for Development and Environment, University of Bern.