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)

Mekelle University (Mekelle University) - Ethiopie

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

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

11/11/2012

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:

It is a raised wall constructed across a stream/gully using stone, concrete and/or gabion for dual purpose, namely, to pond/store the stream flow behind it for irrigation purpose while at the same time reducing the runoff velocity and enhancing gully rehabilitation.

2.2 Description détaillée de la Technologie

Description:

A check dam pond is a raised wall constructed across a gully from stone, concrete and/or gabion to store water behind it for irrigation purpose using either gravity or lifting mechanism. The structure generally consists of construction of foundation, apron, retaining wall and the checkdam. The width of the checkdam ranges between 1 - 2 m while the height varies between 1 - 2 m depending up on the gully depth. The length of the checkdam depends on the gully width. The spacing between adjacent checkdams is determined based on two factors, namely, the gradient of the river bed and the availability of potential land that can be irrigated. It is also provided with a number of sluice gates which will be removed during the main rainy season to minimize siltation.

Purpose of the Technology: In addition to storing water for irrigation, check dam ponds decrease slope length, slope angle, runoff velocity and minimize soil erosion.

Establishment / maintenance activities and inputs: Establishment of a check dam pond starts with collection and transportation of stone and sand. The construction is started by setting out the dimensions from the design on the selected site and excavating the foundation for the different parts, namely, key trench, apron and retaining wall. The check dam is then constructed using gabions filled with stones and tightly tied together with wire. Finally the superstructure is plastered using mortar to prevent the passage of water through the body. Gates of about 1 m wide are finally constructed at about 1 m interval and fitted with sluice gates. Maintenance usually involves fixing damaged gates and reinforcing gabions.

Natural / human environment: Check dam pond is implemented in gentle (2 - 5%) and moderate (5 - 8%) slopes and in medium and light soil types of at least 1 m depth. It increases water availability for irrigation and livestock consumption purposes. It also reduces runoff velocity thereby decreasing soil erosion and enhancing gully rehabilitation.

It requires skilled labour and high construction cost. As a result, it is constructed through external support. However, the number of communities seeking for external support and willing to contribute their share is at the rise. The technology minimizes greatly the risk of crop failure and improves the livelihood of the land users.

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 moins de 10 ans (récemment)

2.7 Introduction de la Technologie

Spécifiez comment la Technologie a été introduite: :

• par le biais de projets/ d'interventions extérieures

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 and overgrazing, high erosion risk, gully formation and land loss, decline in productivity.

Major land use problems (land users’ perception): Population pressure, deforestation, flood, soil erosion, reduced productivity.

3.3 Informations complémentaires sur l'utilisation des terres

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

• mixte: pluvial-irrigué

Nombre de période de croissance par an: :

• 2

Précisez:

Longest growing period in days: 150Longest growing period from month to month: June - NovemberSecond longest growing period in days: 105Second longest growing period from month to month: January - April

3.4 Groupe de GDT auquel appartient la Technologie

• récupération/ collecte de l'eau
• gestion de l'irrigation (incl. l'approvisionnement en eau, le drainage)
• gestion des eaux de surface (sources, rivières, lacs, mers)

3.5 Diffusion de la Technologie

Spécifiez la diffusion de la Technologie:

• répartie uniformément sur une zone

Si la Technologie est uniformément répartie sur une zone, indiquez la superficie couverte approximative:

• 1-10 km2

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, Wm: mass movements / landslides, Wo: offsite degradation effects

Main causes of degradation: deforestation / removal of natural vegetation (incl. forest fires), Heavy / extreme rainfall (intensity/amounts), other natural causes (avalanches, volcanic eruptions, mud flows, highly susceptible natural resources, extreme topography, etc.) specify (Steep topography that increases amount and velocity of flood), population pressure

Secondary causes of degradation: crop management (annual, perennial, tree/shrub), over-exploitation of vegetation for domestic use, overgrazing, floods, land tenure, poverty / wealth, education, access to knowledge and support services

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:

Main goals: mitigation / reduction of land degradation

Secondary goals: rehabilitation / reclamation of denuded land

4.1 Dessin technique de la Technologie

4.2 Spécification/ explications techniques du dessin technique

Check dam ponds are raised walls constructed across a stream/gully using stone, concrete and/or gabion for dual purpose, namely, to pond/store the stream flow behind it for irrigation purpose while at the same time reducing the runoff velocity and enhancing gully rehabilitation.

Location: Tigray. Kilte Awlaelo

Date: 10/10/2014

Technical knowledge required for field staff / advisors: high

Technical knowledge required for land users: high

Technical knowledge required for Engineer/designer: high

Main technical functions: control of dispersed runoff: impede / retard, reduction of slope length

Secondary technical functions: reduction of slope angle, increase of infiltration, increase of groundwater level / recharge of groundwater, sediment retention / trapping, sediment harvesting

Wall/ barrier
Vertical interval between structures (m): n/a
Spacing between structures (m): n/a
Height of bunds/banks/others (m): 1 - 2
Width of bunds/banks/others (m): 1 - 2

Construction material (stone): Stones are usually shaped in order to piece together very well.

Construction material (concrete): The chekdam is usually plastered by concrete on the upstream side to prevent the passage of water th

Construction material (other): Gabion, Sheet metal and Angle iron.

Slope (which determines the spacing indicated above): 2 - 8%

Lateral gradient along the structure: 0%

4.3 Informations générales sur le calcul des intrants et des coûts

autre/ monnaie nationale (précisez):

Birr

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

18,0

4.4 Activités de mise en place/ d'établissement

	Activité	Type de mesures	Calendrier
1.	Site clearance and excavation of foundation	Structurel	Dry season
2.	Stone collection and transportation	Structurel	Dry season
3.	Sand collection and transportation	Structurel	Dry season
4.	Gabion masonry work	Structurel	Dry season
5.	Plastering	Structurel	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	4678,0	4678,0	25,0
Matériaux de construction	Cement	ha	1,0	953,0	953,0
Matériaux de construction	Gabion	ha	1,0	6268,0	6268,0
Matériaux de construction	Sheet metal	ha	1,0	44,0	44,0
Matériaux de construction	Angle iron	ha	1,0	56,0	56,0
Coût total de mise en place de la Technologie					11999,0

Commentaires:

Duration of establishment phase: 6 month(s)

4.6 Activités d'entretien/ récurrentes

	Activité	Type de mesures	Calendrier/ fréquence
1.	Fixing damaged gates and reinforcing gabions	Structurel	Dry season

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

Commentaires:

Machinery/ tools: Digging hoe, shovel, hammer, crow bar

Since the check dam ponds generally vary in depth, width and most importantly in length depending up on the gully profile, calculation of cost per meter length will not be a reliable presentation. As a result, one typical check dam pond was selected and the total volume of the structure and the corresponding total cost of construction calculated. Then, the cost per cubic meter of the check dam was determined by dividing the total construction cost to the total volume of the structure.

The calculation includes the cost for the purchase of industrial materials (cement, gabion, sheet metal and angle iron) and cost of labour used for the construction including site clearance and excavation of foundation, stone and sand collection and transportation, gabion masonry work and plastering.

The price of the industrial materials and the labour wage used in the cost calculation apply to 2012. The daily labour wage for plastering is 180 Birr while it is 50 Birr for all other works.

4.8 Facteurs les plus importants affectant les coûts

Décrivez les facteurs les plus importants affectant les coûts :

Labour, availability of construction material, depth and width of gully.

5.1 Climat

5.2 Topographie

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 fertility is low (medium soils, ranked 1) and very low (light soils, ranked 2)
Soil drainage/infiltration is medium (ranked 1) and good (ranked 2)
Soil water storage capacity is medium (ranked 1) and low (ranked 2)

5.4 Disponibilité et qualité de l'eau

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

Availability of surface water is good (September - January). Also medium (February-June)

5.5 Biodiversité

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: 2% - 3%
10% of the land users are rich and own 10% of the land.
60% of the land users are average wealthy and own 55% of the land (35 Birr/day/person).
30% of the land users are poor and own 35% of the land.

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:

• état

Droits d’utilisation des terres:

• communautaire (organisé)
• individuel

Droits d’utilisation de l’eau:

• communautaire (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

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)

Extrêmes climatiques (catastrophes)

Catastrophes hydrologiques

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

6.5 Adoption de la Technologie

Commentaires:

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

500 land user families have adopted the Technology with external material support

There is no trend towards spontaneous adoption of the Technology

Comments on adoption trend: There is no trend for spontaneous adoption due to high costs. However, communities are increasingly seeking external support to implement this technology.

6.7 Points forts/ avantages/ possibilités de la Technologie

Points forts/ avantages/ possibilités du point de vue de l'exploitant des terres
Increased water availability for irrigation and livestock consumption How can they be sustained / enhanced? Watershed management
Reduced soil erosion How can they be sustained / enhanced? Construction of retaining walls
Increased employment opportunity and income from irrigation How can they be sustained / enhanced? Cultivation of high value crops

Points forts/ avantages/ possibilités du point de vue du compilateur ou d'une autre personne ressource clé
Increased water availability for irrigation as well as livestock consumption How can they be sustained / enhanced? Integrated watershed management
Reduce slope length, angle and erosion risk and enhance gully rehabilitation How can they be sustained / enhanced? Regular maintenance of the structure

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

Faiblesses/ inconvénients/ risques du point de vue du compilateur ou d'une autre personne ressource clé	Comment peuvent-ils être surmontés?
High cost of construction	Selecting a site that has good availability of construction material and that can irrigate as large area as possible.
Require skilled labour	Training of land users
Labour intensive	Mass mobilization

7.2 Références des publications disponibles

Titre, auteur, année, ISBN:

Staff members of the Kilte Awlaelo Wereda Office of Agriculture and Rural Development and Office of Water Resources Development