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

Nom du projet qui a facilité la documentation/ l'évaluation de la Technologie (si pertinent)

Water and Land Resource Centre Project (WLRC)

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

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

12/05/2014

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

Oui

1.4 Déclaration sur la durabilité de la Technologie décrite

Est-ce que la Technologie décrite ici pose problème par rapport à la dégradation des terres, de telle sorte qu'elle ne peut pas être déclarée comme étant une technologie de gestion durable des terres?

Non

1.5 Référence au(x) questionnaire(s) sur les Approches de GDT

2.1 Courte description de la Technologie

Définition de la Technologie:

Vegetated graded soil bund is a soil conservation practice meant for cultivated lands and constructed by excavating graded channel on upper side and develop embankment on lower side which is planted with grass or shrub species in order to control soil erosion and drain excess runoff implemented through community mobilization.

2.2 Description détaillée de la Technologie

Description:

Vegetated graded soil bund is a practice or soil conservation technology for cultivated lands and constructed by excavating graded channel and form embankment. It is practiced in areas where there is excess runoff to be disposed and where there is no stones available for construction. The design specifications (ditch gradient, width and height) and layout (spacing/vertical interval) vary on the amount of excess runoff and slope of the land. Soil bund construction begins from top of the catchment. Cut off drains are constructed on top of the catchment and where needed to drain excess runoff to well stabilized natural or man-made waterways. this helps to reduce runoff impact on gullies. The bund ditch/channel should be sufficient enough to drain excess runoff safely without causing channel erosion and creating downstream damages. At same time the embankment should be stable to withstand overflows and damage due to free grazing. One technique to stabilize bunds is to plant the embankment with grass and shrub species of multiple economic value in order to compensate production area lost by bund construction. Often, the species are preferably used for livestock feed. Thus, free grazing has to be controlled. To protect damage of channels and embankments by extreme runoff and floods, frequent supervision and maintenance is required.

The purposes are:
1) Reduce nutrient loss and soil erosion by shortening the slope length,
2) Safely drain excess runoff from upstream of gully into protected waterways,
4) Produce biomass of fodder and cash values.

Vegetated graded bunds are established by doing surveying using hand level to determine the layout of the technology along the slope. During the surveying, the position of bunds (spacing) and cutoff drains and connection to waterways are determined. Bunds are laid following 0.05% gradient and up to 80 m maximum length. The specifications of the structure are: height of bund is a minimum of 60 cm after compaction; depending on the soil, base width range between 1.0 and 1.5m; top width is between 30 and 50 cm. The construction is made across different parcels owned by different land users. If there is no natural waterways and where it is appropriate, paved waterways are constructed at every 80 m or less bund length to dispose drainage water. At the beginning of the rainy season, the embankments are covered with grass and/or shrubs either by direct sowing of seeds or planting the seedlings raised in the nurseries. Monitoring of damages due to flooding and animals, maintenance of the structure as well as replanting of dead seedlings on bunds is required to sustain the soil conservation technology.

The technology is appropriately applied in high rainfall and sub-humid areas of the sub-tropics, particularly where the soil is moderately deep and poorly drained. It is constructed on cultivated lands having slopes in the range of 3-15%. The practice can be constructed by land users. It also requires collective decision and actions to drain excess runoff through waterways. The living condition depends on subsistence crop-livestock mixed farming. On average households have 5-6 family size. Crop production is meant for home consumption with small surplus for local market. The services related to water supply, energy supply, and infrastructure are low. Besides it is an asset, animals often used to cope shocks during drought periods.

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

Commentaires (type de projet, etc.) :

The soil bunds are introduced before 30-40 years, however the integration of structural and combination of vegetative measures are applied in three years period in the WLRC learning watersheds.

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): Land degradation due to sheet erosion, rills and gullies, soil nutrient depletion, overgrazing, shortage of fuel wood, excessive removal of crop residuals, loss of vegetation and deforestation
Major land use problems (land users’ perception): Soil erosion, soil nutrient depletion, shortage of pasture

3.3 Informations complémentaires sur l'utilisation des terres

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

• pleine irrigation

Nombre de période de croissance par an: :

• 1

Précisez:

Longest growing period in days: 210, Longest growing period from month to month: June-December; Second longest growing period in days: 180, Second longest growing period from month to month: June-November

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 20 m2.
The technology is applied on specific conditions within the watersheds or area of adoption

3.6 Mesures de GDT constituant la Technologie

Commentaires:

Type of vegetative measures: aligned: -graded strips

3.7 Principaux types de dégradation des terres traités par la Technologie

Commentaires:

Main causes of degradation: soil management (High tillage frequency on annual basis and steep slope cultivation), crop management (annual, perennial, tree/shrub) (The cropping system is cereal based that induce erosion), overgrazing (Livestock graze on crop residues after harvesting of crops), Heavy / extreme rainfall (intensity/amounts) (Extreme rainfall cause for high erosion), other natural causes (avalanches, volcanic eruptions, mud flows, highly susceptible natural resources, extreme topography, etc.) specify (Steep slopes or rugged topography), population pressure (Result in expansion of crop lands to steeper slopes)
Secondary causes of degradation: deforestation / removal of natural vegetation (incl. forest fires) (Deforestation of scattered trees in the farm and forests upstream of crop lands), land tenure (Insecure tenure play role not to invest on long term), poverty / wealth (Poor can not afford to invest on soil conservation on his parcel), education, access to knowledge and support services, governance / institutional

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

4.1 Dessin technique de la Technologie

4.2 Spécification/ explications techniques du dessin technique

Vegetated graded soil bund showing the excavated ditch or channel and the embankment planted with grass and shrubs
Location: Amhara Region. Mecha, Yilmana Densa, Bahir Dar Zuria and Dessie Z

Technical knowledge required for field staff / advisors: high (Layout and design specification of soil bunds and cutoff drains vary on soil types, slopes, and rainfall conditions. Experts thus should acquire knowledge on specific hydrologic conditions)
Technical knowledge required for land users: moderate (Land users need skill to layout and construct bunds, monitor structures before the occurrence of excessive damage, and do regular maintenance)

Main technical functions: control of dispersed runoff: impede / retard, reduction of slope length, sediment retention / trapping, sediment harvesting, increase of biomass (quantity)
Secondary technical functions: control of dispersed runoff: retain / trap, reduction of slope angle, increase / maintain water stored in soil, increase of groundwater level / recharge of groundwater

Aligned: -graded strips
Vegetative material: T : trees / shrubs, C : perennial crops, G : grass
Number of plants per (ha): T=5333, C=160, G=1600
Vertical interval between rows / strips / blocks (m): 1-1.5
Spacing between rows / strips / blocks (m): 10-20
Vertical interval within rows / strips / blocks (m): T=0.3, C=5, G=0.5
Width within rows / strips / blocks (m): 0.3
Trees/ shrubs species: Cordia Africana, Polycantha, Sesbania Susban, Pigeon pea, Treelucer
Perennial crops species: Rhamnus
Grass species: Napier grass
Slope (which determines the spacing indicated above): 3-15%
Gradient along the rows / strips: 0.05%
Diversion ditch/ drainage
Depth of ditches/pits/dams (m): 0.3-0.7
Width of ditches/pits/dams (m): 1.2-2.8
Length of ditches/pits/dams (m): 100-250

Waterway
Depth of ditches/pits/dams (m): 0.3
Width of ditches/pits/dams (m): 1.5-2.0

Bund/ bank: graded
Vertical interval between structures (m): 1-1.5
Spacing between structures (m): 10-20
Depth of ditches/pits/dams (m): 0.5
Width of ditches/pits/dams (m): 0.3
Height of bunds/banks/others (m): 0.6
Width of bunds/banks/others (m): 1-1.5
Length of bunds/banks/others (m): 50-80

Construction material (earth): in-situ excavated soil
Slope (which determines the spacing indicated above): 3-15%
Lateral gradient along the structure: 0.05%
Vegetation is used for stabilisation of structures.

4.3 Informations générales sur le calcul des intrants et des coûts

autre/ monnaie nationale (précisez):

ETH BIRR

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

20,0

4.4 Activités de mise en place/ d'établissement

	Activité	Type de mesures	Calendrier
1.	Preparing planting materials	Végétale	January-May
2.	Preparation of planting materials	Végétale	January-May
3.	Transportation of grass splits/cuttings	Végétale	Start of rainy season/July
4.	Transporting tree seedlings	Végétale	Start of rain season/July
5.	Planting grass splits/cuttings	Végétale	Start of rainy season/July
6.	Sowing seeds on bunds	Végétale	Start of rainy season/July
7.	Planting tree seedlings on bunds	Végétale	Starting of rainy season/July
8.	Surveying (layout of structures)	Structurel	After crop harvest and before first tillage operation
9.	Construction of cutoff drains	Structurel	January-April
10.	Construction of bunds (ditch and embankment)	Structurel	January-April
11.	Construction of waterways	Structurel	January - April

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	1107,0	1107,0	79,0
Equipements	animal traction	ha	1,0	4,0	4,0	100,0
Equipements	tools	ha	1,0	300,6	300,6	50,0
Matériel végétal	seedlings	ha	1,0	32,0	32,0	100,0
Matériel végétal	seeds	ha	1,0	9,0	9,0	100,0
Matériel végétal	compost manure	ha	1,0	2,0	2,0	100,0
Matériaux de construction	stone	ha	1,0	1300,0	1300,0	100,0
Matériaux de construction	wood	ha	1,0	110,0	110,0	100,0
Matériaux de construction	earth	ha	1,0	25,2	25,2	100,0
Coût total de mise en place de la Technologie					2889,8

Commentaires:

Duration of establishment phase: 15 month(s)

4.6 Activités d'entretien/ récurrentes

	Activité	Type de mesures	Calendrier/ fréquence
1.	Preparation of planting materials	Végétale	January - May
2.	Transportation of seedlings	Végétale	July
3.	Re-plantation of seedlings and grass splits	Végétale	July
4.	Maintenance of bunds, cutoff drain and waterways	Structurel	January-April

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	279,0	279,0	100,0
Matériel végétal	seedlings	ha	1,0	20,0	20,0	100,0
Coût total d'entretien de la Technologie					299,0

Commentaires:

Machinery/ tools: Cart, plastic tubes, spade, pickaxe, hand level, graduated ranging pole, spade, pickaxe, crowbar, hammer
The costs are calculated based on the labour, seedling/seed, grass splits required per hectare

4.8 Facteurs les plus importants affectant les coûts

Décrivez les facteurs les plus importants affectant les coûts :

The cost variation in implementing vegetated soil bund is dependent upon availability of stones, workability of the soil, cost of seeds or seedlings for plantation, and distance for transporting seedlings.

5.1 Climat

5.2 Topographie

5.3 Sols

5.4 Disponibilité et qualité de l'eau

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
Difference in the involvement of women and men: Women are involved in the construction of bunds with role of collecting stones, stabilize/compact the embankments and sometimes help men in excavating the earth
Population density: 200-500 persons/km2
Annual population growth: 2% - 3%
80% of the land users are average wealthy.
20% of the land users are poor.
Off-farm income specification: Land users often do not have access to off-farm income unless those who are young and own small size of land go for seasonal labor to towns during the slack period

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:

• individuel

Droits d’utilisation de l’eau:

• accès libre (non organisé)
• communautaire (organisé)

5.9 Accès aux services et aux infrastructures

6.1 Impacts sur site que la Technologie a montrés

Impacts socio-économiques

Production

Revenus et coûts

Impacts socioculturels

Impacts écologiques

Cycle de l'eau/ ruissellement

Sols

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 météorologiques

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

Catastrophes hydrologiques

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

Commentaires:

The technology has sufficient drainage ditch to tolerate excess runoff occurred during heavy rainfall events. However, it is sensitive to floods unless flood management measures such as strong cutoff drains and waterways are implemented

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:

The short term economic benefits of the technology includes increase in fodder production and slightly crop productivity due to improved soil moisture. Whereas the long term benefit can be obtained as a result of increased yield on areas where sediment accumulation occurs as well as production of fodder on soil bunds for livestock feed

6.5 Adoption de la Technologie

Commentaires:

The technology is implemented using community mobilization approach which involves all land users. All land users, who cultivate land in areas where bunds are suitable, implemented the technology. All parcels are covered with the technology/bunds except homesteads and degraded hillsides and gullies which are treated with different SLM technologies
Since the approach encourages collective action (through community organizations) to integrate different SLM technologies in the watershed level, there is no attempt by individual land users. However, there are motivations and implementation of land users on adjacent watersheds to implement the technology.
There is a moderate trend towards spontaneous adoption of the Technology
The trend is at increasing rate although land users need material support such as multipurpose seedlings to stabilize bunds. There is shortage of supply of fodder seeds. Community nurseries are inadequate and not well supported to raise seedlings to meet community demands.

6.7 Points forts/ avantages/ possibilités de la Technologie

Points forts/ avantages/ possibilités du point de vue de l'exploitant des terres
Increase in fodder production for livestock feed
Reduce conflict among adjacent land users (i.e., upstream and downstream land users) that arise due to concentrated runoff
Reduce soil erosion

Points forts/ avantages/ possibilités du point de vue du compilateur ou d'une autre personne ressource clé
The technology reduces soil loss and associated nutrient loss significantly in the first 3 to 4 years and further reduce siltation of reservoirs and land degradation
Increase the soil moisture in the landscape/watershed
Improves the greenness, soil carbon and micro-climate
Increase level of awareness of land users to produce fodder and diversify production and income
Reduce the concentration of runoff and safely drain without causing damage

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?
Hinder farm operations like turning oxen become difficult while ploughing	It can be sustained through proper layout and allow space for human and animal paths
Plantation on bunds harbor birds	This can be avoided by harvesting the mature branches of the shrubs for livestock feed on seasonal basis.
Appearance of new weeds species along the drainage ditches	Regular weed monitoring and manual control
Hinders livestock to graze on crop residues	Try to use cut and carry grazing system (both crop residues and fodders) and develop forage development strategies in every possible niches

Faiblesses/ inconvénients/ risques du point de vue du compilateur ou d'une autre personne ressource clé	Comment peuvent-ils être surmontés?
High labor requirement to establish and maintain the technology	Increase the awareness level of land users and strength collective actions and local organizational setups
Small land loss for construction	Introduce production options (like fodder production) on bunds to compensate the lost land
It requires some years to accumulate sediment on bund area and form bench	It can be improved by modifying the design of drainage ditchs

7.1 Méthodes/ sources d'information

7.2 Références des publications disponibles

Titre, auteur, année, ISBN:

Vegetated Graded Soil Bund: A Technique to Reduce Runoff Impact and Increase Soil Moisture Storage and Fodder Biomass, WLRC Brief No. 4

Disponible à partir d'où? Coût?

WWW.wlrc-eth.org