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)

Book project: where the land is greener - Case Studies and Analysis of Soil and Water Conservation Initiatives Worldwide (where the land is greener)

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

GEOTEST AG (GEOTEST AG) - Suisse

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

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

01/09/2003

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

Oui

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

2.1 Courte description de la Technologie

Définition de la Technologie:

Integrated gully treatment consisting of several simple practices including stone and wooden check dams, cut-off drains and reforestation in sediment traps (biotrampas).

2.2 Description détaillée de la Technologie

Description:

The focus of the case study is a degraded catchment, located at high altitude (2,800–4,200 m a.s.l.), home to 37 households, which is characterised by severe gullies and landslides. Gullies are continuously expanding, and constitute a significant proportion of the catchment. These cause considerable loss of cropland as well as downstream damage to the city of Cochabamba.
A combination of structural and vegetative measures was designed and implemented with the purpose of: (1) preventing affected areas from further degradation by safely discharging runoff from the surrounding area through the main gullies down to the valley; (2) gradually stabilising the land through the regeneration of vegetative cover; (3) reducing downstream damage through floods and siltation; (4) ensuring accessibility to the mountainous agricultural area during the rainy season.
Cut-off drains at the heads of the gullies, reinforced with stones inside the channel and grassed bunds below, concentrate runoff and cascade it down over stone steps back into the waterways. Flow is controlled by stone and wooden check dams and discharged safely. Sediment is trapped behind these structures and terraces develop. Bushes or trees are planted above and below the check dams. Depending on availability of materials, wooden check dams are sometimes used and associated with tree planting (four trees above and four below each check dam).
These practices are complemented by SWC measures throughout the catchment: biotrampas are staggered sediment traps located on the steep lateral slopes. They comprise ditches behind wooden barriers where soil accumulates. Biotrampas create suitable sites for tree/bush planting while stabilising the hillsides, reducing erosion, increasing infiltration and slowing siltation of the check dams in the watercourses. Supporting technologies include fenced-off areas for reforestation of the lateral slopes/upper edge of the gully, and finally large gabion dams at the outlets of the gullies, usually 10-25 m in length, but exceptionally up to 200 m.
After a few years vegetation should have stabilised the system, and effectively replaced the wooden and stone constructions. The various practices enhance each other. Establishment is labour demanding, but other costs are low, as long as the material in question is locally obtainable. Maintenance costs are also low. The technology was implemented over a period of six years, starting in 1996, through the Programa de Manejo Integral de Cuencas (PROMIC).

2.3 Photos de la Technologie

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

2.7 Introduction de la Technologie

Spécifiez comment la Technologie a été introduite: :

• par le biais de projets/ d'interventions extérieures

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 and poorly managed channel irrigation in areas with steep slopes: poorly structured soils and
extreme climatic variability causing erosion gullies, landslides, downstream flooding and sedimentation of agricultural land and settlements - including the city of Cochabamba.

Other grazingland: extensive grazing

3.3 Informations complémentaires sur l'utilisation des terres

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

• pluvial

Précisez:

Longest growing period in days: 210 Longest growing period from month to month: Oct - Apr

3.4 Groupe de GDT auquel appartient la Technologie

• mesures en travers de la pente
• dérivation et drainage de l'eau

• Sediment traps

3.5 Diffusion de la Technologie

Commentaires:

Total area covered by the SLM Technology is 6 m2.

3.6 Mesures de GDT constituant la Technologie

3.7 Principaux types de dégradation des terres traités par la Technologie

Commentaires:

Main type of degradation addressed: Wg: gully erosion / gullying, Wm: mass movements / landslides, Wo: offsite degradation effects, Bq: quantity / biomass decline

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:

• restaurer/ réhabiliter des terres sévèrement dégradées

4.1 Dessin technique de la Technologie

4.2 Spécification/ explications techniques du dessin technique

Gully control and catchment protection: an overview of the integrated measures.

Technical knowledge required for field staff / advisors: moderate

Technical knowledge required for land users: moderate

Main technical functions: reduction of slope angle, reduction of slope length, improvement of ground cover, increase in organic matter, sediment retention / trapping, sediment harvesting, control of concentrated runoff

Secondary technical functions: increase of infiltration, control of dispersed runoff

Vegetative measure: grassed bunds
Vegetative material: G : grass

Vegetative measure: aligned trees
Vegetative material: G : grass

Vegetative measure: Vegetative material: G : grass

Vegetative measure: Vegetative material: G : grass

Structural measure: cut-off drains

4.4 Activités de mise en place/ d'établissement

	Activité	Type de mesures	Calendrier
1.	Plant local bushes and trees in front and behind the biotrampas andthe check dams (after sedimentation). Altitude acclimatisation (2 weeks)is required for the trees before planting.	Végétale
2.	Cut-off drains: excavate channel above the gully. Lay stones in the bedand plant local bushes or grass on the bund below the ditch. The outletof the ditch into the gully is stabilised by a few stone steps.	Structurel
3.	Stone check dams: excavate a ditch perpendicular to the water channel	Structurel	during the dry season
4.	Wooden check dams (up to 8 m long, 15–20 cm wide and 1 m high):soil excavation (see 2.). Fix logs with wire or nails to vertical poles.Position a bio-fibre fleece behind the dam to prevent sediment fromflowing through.	Structurel
5.	Biotrampas: excavate soil, hammer wooden posts into the soil andfix 2–3 horizontal logs with nails or wire to the wooden posts.	Structurel	(During dry season)
6.	Plant local bushes and trees in front and behind the biotrampas andthe check dams (after sedimentation). Altitude acclimatisation (2 weeks)is required for the trees before planting. Establish fences to protect the plants.	Structurel

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	48,0	48,0
Equipements	Tools	ha	1,0	4,0	4,0
Matériel végétal	Seedlings	ha	1,0	19,0	19,0
Matériaux de construction	Stone	ha	1,0
Matériaux de construction	Wood	ha	1,0	33,0	33,0
Matériaux de construction	Nails, wire	ha	1,0	2,0	2,0
Matériaux de construction	Bio-fibre fleece	ha	1,0	4,0	4,0
Coût total de mise en place de la Technologie					110,0

4.6 Activités d'entretien/ récurrentes

	Activité	Type de mesures	Calendrier/ fréquence
1.	Biotrampas: pruning the trees	Végétale	/every three years.
2.	Cut-off drains: clearing of sediment, cutting bushes and grasses.	Végétale
3.	Stone check dams: pruning trees and bushes. After full sedimentation, the dam may be increased in height.	Végétale	/every three years.
4.	Wooden check dams: pruning trees and bushes	Végétale	/every three years

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	12,0	12,0	100,0
Equipements	Tools	ha	1,0	1,0	1,0	100,0
Matériel végétal	Seedlings	ha	1,0	1,0	1,0	100,0
Matériaux de construction	Stone	ha	1,0
Matériaux de construction	Wood	ha	1,0	1,0	1,0	100,0
Matériaux de construction	Nails, wire	ha	1,0	1,0	1,0	100,0
Coût total d'entretien de la Technologie					16,0

Commentaires:

Costs have been calculated for the whole catchment (6 km2) – including 100 m of cut-off drains, 6,750 m of stone
check dams, 1,500 m of wooden check dams and 770 biotrampas – and then divided by the number of hectares. Wood is not locally available (because of national park laws) and needs to be brought into the area. Establishment and maintenance costs were paid by PROMIC during their intervention period of 6 years. The (high) costs of the gabion weirs further downstream are not included as these are not always required and vary considerably in size from site to site.

5.1 Climat

5.2 Topographie

Commentaires et précisions supplémentaires sur la topographie:

Slopes on average: Also very steep and hilly (both ranked 2) and moderate and rolling (both 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: Also Very shallow (ranked 2) and shallow as well as deep (both ranked 3)
Soil fertility: Low and very low
Topsoil organic matter: High (on the cropland at high altitudes) and low (in the gullies)
Soil drainage/infiltration: Medium

5.6 Caractéristiques des exploitants des terres appliquant la Technologie

Indiquez toute autre caractéristique pertinente des exploitants des terres:

Market orientation: Subsistence (mostly subsistence (self-supply) with low market income)

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

• communal grassland

Droits d’utilisation des terres:

• communautaire (organisé)
• individuel

6.1 Impacts sur site que la Technologie a montrés

Impacts socio-économiques

Production

Revenus et coûts

Impacts socioculturels

Impacts écologiques

Sols

6.2 Impacts hors site que la Technologie a montrés

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

Parmi tous ceux qui ont adopté la Technologie, combien d'entre eux l'ont fait spontanément, à savoir sans recevoir aucune incitation matérielle ou aucun paiement?

• 0-10%

Commentaires:

100% of 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: Only a few farmers have built new structures post-project. This is due to different reasons: (1) PROMIC stopped its financial support; (2) the gullied areas are not used by farmers, therefore they have little reason to protect them; (3) the catchment is w

6.7 Points forts/ avantages/ possibilités de la Technologie

Points forts/ avantages/ possibilités du point de vue du compilateur ou d'une autre personne ressource clé
Reduction of landslips and flooding in the valley How can they be sustained / enhanced? New small gullies may originate inside an existing gully or around it. It is important to continue to maintain the current measures and construct new, even though the subsidies of PROMIC have been terminated.
The technology could be implemented by the farmers themselves as materials (except for wood) and tools are locally available How can they be sustained / enhanced? Prolong the sensitisation work to convince the farmers of the necessity and benefits of the technology.
Reduction of soil loss in the watershed How can they be sustained / enhanced? Do not apply the mentioned practices in isolation but always in combination.
Simple technology with high positive long-term impact, especially downstream.

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?
The technology doesn’t address the root cause of human induced gully erosion	Alongside the gully control technology it is necessary to apply complementary conservation measures on the cropland above the gully to prevent new gully development.
High labour input for establishment of SWC measures.	An agreement on sustainable use of trees should be made with the national park authority.
The technology partly depends on inputs that are not available locally: timber for establishment of wooden structures (which is a significant quantity) are brought in from outside (since the area is within a national park tree felling is not allowed)

7.2 Références des publications disponibles

Titre, auteur, année, ISBN:

Documentation of PROMIC (see address above)

Disponible à partir d'où? Coût?

PROMIC, Programa de Manejo Integral
de Cuencas, Av. Atahuallpa final, Parque Tunari, casilla 4909, Cochabamba, Bolivia; promic@promic-bolivia.org; www.promic-bolivia.org