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)

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

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

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) Questionnaires sur les Approches de GDT (documentées au moyen de WOCAT)

Regional rural development programme [Espagne]

Regional development programme to protect natural resources and stimulate rural economies.

• Compilateur : Joris De Vente
• 12 mai 2009 00:00

2.1 Courte description de la Technologie

Définition de la Technologie:

Earth-banked terraces in cereal and almond cropland covered with drought-resistant shrubs.

2.2 Description détaillée de la Technologie

Description:

Earth-banked terraces are constructed by carefully removing a superficial soil layer (~10-20 cm) from one part of a field, concentrating it on the lower end of that field in order to reduce slope gradient and length. Another terrace is created directly downslope to form a cascade of terraces. Terrace risers have to be of restricted height (~50-150 cm) to prevent steep and unstable terraces. Stones from the fields can be used to reinforce the terrace ridge. After terrace construction, fields should be gently sloping (<3%) in the direction of the main slope. The distance between terraces must be enough to allow tractor movement during normal cultivation activities and it depends also on the slope gradient. The steeper the slope, the shorter is the distance between terraces. Terraces reduce the formation of gullies and retain water from upslope. The terraces are made with locally available machinery (tractor, small bulldozer). The terrace ridges are optimal locations to plant olives, almonds or fruit trees. Moreover, to be most effective, the terrace ridges are vegetated with shrubs adapted to semi-arid conditions and with a good surface cover (>~30%) throughout the year (e.g. Stipa tenacisima, Rosmarinus officinalis, Thymus vulgaris, Ulex parviflorus, Rhamnus lycioides, Pistacia lentiscus). Natural regeneration of vegetation is allowed without limitation on the terrace ridges, so no herbicide application or burning are carried out to remove weeds. Where possible, regeneration should be stimulated by planting the same adapted species in at least 25% of the terrace ridge. Optionally, in the other 75% of the terrace ridge, cereals or other leguminous species can be sown, but should not be harvested or used for grazing.

Purpose of the Technology: This technology reduces flooding, damage to infrastructure and siltation of water reservoirs, while maintaining (or slightly increasing) crop productivity. This is achieved by reducing runoff, soil erosion and hydraulic connectivity through a decreased slope gradient and an increased vegetation cover. The terrace ridge functions as a sink for runoff within fields and reduces runoff velocity. The vegetation leads to increased soil organic matter content below plants, producing an improved soil structure and a higher infiltration capacity. The use of stones from the fields to reinforce the terraces is optional, but facilitates crop production in the fields and makes the ridges more resistant to higher runoff velocities. The technology requires an initial investment in the construction of the terraces. Terraces can best be located on thalwegs and on areas where gully formation is often observed. Maintenance consists of filling up possible bank gullies developed in the terraces after important rainfall events and, if needed, substitute decayed shrubs with new ones.

Natural / human environment: The technology is generally applied on soils of shallow to medium depth (20 – 60 cm), and slopes are gentle to moderate (5-15%). The climate is semi-arid with a mean annual rainfall around 300 mm. Droughts, peaking in summer commonly last for more than 4-5 months. Annual potential evapotranspiration rates larger than 1000 mm are common. The production system is highly mechanized and market-oriented but depends strongly on agricultural subsidies. All cropland is privately-owned.

2.3 Photos de la Technologie

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

Pays:

Espagne

Région/ Etat/ Province:

Murcia

Autres spécifications du lieu:

Guadalentin catchment

Spécifiez la diffusion de la Technologie:

• répartie uniformément sur une zone

S'il n'existe pas d'informations exactes sur la superficie, indiquez les limites approximatives de la zone couverte:

• 10-100 km2

Map

×

2.6 Date de mise en œuvre de la Technologie

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

• il y a plus de 50 ans (technologie traditionnelle)

2.7 Introduction de la Technologie

Spécifiez comment la Technologie a été introduite: :

• dans le cadre d'un système traditionnel (> 50 ans)

Commentaires (type de projet, etc.) :

Most of the earthen terraces are already much older than 50 years. Recently, the regional administration is promoting clearly defined vegetated strips with minimum dimensions in order to apply for subsidies.

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

Les divers types d'utilisation des terres au sein du même unité de terrain: :

Oui

Précisez l'utilisation mixte des terres (cultures/ pâturages/ arbres):

• Agroforesterie

Terres cultivées

• Cultures annuelles
• Plantations d’arbres ou de buissons

Plantations d'arbres et d'arbustes - Précisez les cultures:

• fruits à coque (noix du Brésil, pistaches, noyers de bancoule, amandes)

Nombre de période de croissance par an: :

• 1

Précisez:

Longest growing period in days: 220Longest growing period from month to month: November to June

Pâturages

Forêts/ bois

• Forêts (semi-)naturelles/ bois

Commentaires:

Major land use problems (compiler’s opinion): A lack of water availability seriously limits the production potential of the soil and results in a low vegetation/crop cover. The relatively high soil erosion rates cause various off-site related problems (i.e. flooding, reservoir siltation) and on-site problems (i.e. gully formation and loss of soil depth).

Major land use problems (land users’ perception): Lack of water for irrigation of crops limiting the crop types that can be planted as well as the crop yield of dryland farming.

Number of growing seasons per year:

1

Specify:

Longest growing period in days: 220Longest growing period from month to month: November to June

3.5 Groupe de GDT auquel appartient la Technologie

• Amélioration de la couverture végétale/ du sol
• mesures en travers de la pente

3.6 Mesures de GDT constituant la Technologie

pratiques végétales

• V1: Couverture d’arbres et d’arbustes
• V2: Herbes et plantes herbacées pérennes

structures physiques

• S1: Terrasses

Commentaires:

Main measures: vegetative measures, structural measures

Type of vegetative measures: aligned: -contour

3.7 Principaux types de dégradation des terres traités par la Technologie

érosion hydrique des sols

• Wt: perte de la couche superficielle des sols (couche arable)/ érosion de surface
• Wg: ravinement/ érosion en ravines
• Wo: effets hors-site de la dégradation

dégradation hydrique

• Ha: aridification

Commentaires:

Main type of degradation addressed: Wt: loss of topsoil / surface erosion, Wg: gully erosion / gullying, Wo: offsite degradation effects

Secondary types of degradation addressed: Ha: aridification

Main causes of degradation: crop management (annual, perennial, tree/shrub) (Almond and cereal fields often have a relatively low surface cover by vegetation during long periods of the year, leaving the soil unprotected against raindrop impact and rill or gully formation), disturbance of water cycle (infiltration / runoff) (Reduced infiltration capacity causing runoff and soil erosion), other human induced causes (specify) (Cropping of relatively steep slopes sensitive to erosion because of slope gradient), governance / institutional (spatial planning of land use results in formation of too large fields without field boundaries)

Secondary causes of degradation: Heavy / extreme rainfall (intensity/amounts) (High intensity erosive rainfall is common), droughts (Dry periods and dry years require higher water availability)

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:

• prévenir la dégradation des terres
• réduire la dégradation des terres

Commentaires:

Main goals: prevention of land degradation, mitigation / reduction of land degradation

4.1 Dessin technique de la Technologie

Spécifications techniques (associées au dessin technique):

Quickbird satellite image showing the concentration of terraces along natural drainage lines (thalwegs) where runoff concentrates. Drainage lines are indicated with dotted lines.

Location: Torrealvillla. Murcia

Date: Satellite image 2003

Technical knowledge required for field staff / advisors: moderate (Design of the terraces and selection of the location requires some technical knowledge.)

Technical knowledge required for land users: low (Practical implementation of the terraces does not require a high level of knowledge)

Main technical functions: control of dispersed runoff: retain / trap, control of dispersed runoff: impede / retard, control of concentrated runoff: retain / trap, control of concentrated runoff: impede / retard, reduction of slope angle, increase of infiltration, increase / maintain water stored in soil

Secondary technical functions: reduction of slope length, improvement of ground cover, stabilisation of soil (eg by tree roots against land slides), increase in organic matter, water harvesting / increase water supply, sediment retention / trapping, sediment harvesting, spatial arrangement and diversification of land use

Aligned: -contour
Vegetative material: F : fruit trees / shrubs
Number of plants per (ha): 42
Vertical interval between rows / strips / blocks (m): 1
Spacing between rows / strips / blocks (m): 30-100
Vertical interval within rows / strips / blocks (m): 0.5-7
Width within rows / strips / blocks (m): 2

Vegetative measure: alligned: contour
Vegetative material: G : grass
Number of plants per (ha): >30% cover
Vertical interval between rows / strips / blocks (m): 1
Spacing between rows / strips / blocks (m): 30-100
Vertical interval within rows / strips / blocks (m): 0.5
Width within rows / strips / blocks (m): 2

Vegetative measure: Vegetative material: G : grass

Vegetative measure: Vegetative material: G : grass

Vegetative measure: Vegetative material: G : grass

Fruit trees / shrubs species: natural regeneration of shrubs with possible additional plantation of almond trees and/or woody shru

Grass species: Natural regeneration assisted by seeding of legiminous species and cereals

Slope (which determines the spacing indicated above): 10.00%

Terrace: forward sloping
Vertical interval between structures (m): 1
Spacing between structures (m): 30-100
Height of bunds/banks/others (m): 0.5-1.5
Width of bunds/banks/others (m): 2
Length of bunds/banks/others (m): 50-200

Construction material (stone): Only when many stones are present in the fields

Slope (which determines the spacing indicated above): 5-15%

If the original slope has changed as a result of the Technology, the slope today is: <3%

Lateral gradient along the structure: 0%

Vegetation is used for stabilisation of structures.

Auteur:

Joris de Vente

4.2 Informations générales sur le calcul des intrants et des coûts

autre/ monnaie nationale (précisez):

EURO

Indiquez le taux de change des USD en devise locale, le cas échéant (p.ex. 1 USD = 79.9 réal brésilien): 1 USD = :

0,63

4.3 Activités de mise en place/ d'établissement

4.4 Coûts et intrants nécessaires à la mise en place

Commentaires:

Duration of establishment phase: 12 month(s)

4.5 Activités d'entretien/ récurrentes

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

Commentaires:

Machinery/ tools: For initial construction a large tractor or small bulldozer is required. For maintanance a normal tractor can be used.

The costs were indicated assuming a distance between terraces of 50 meter, meaning two terraces of 100 meter long per hectare. Prices are for spring 2008. Subsidies are foreseen for the installation of the vegetated terraces and for maintenance during at least 4 years if all requirements are fullfilled that are described in the regional development programme.

4.7 Facteurs les plus importants affectant les coûts

Décrivez les facteurs les plus importants affectant les coûts :

Price of fuel and labour are the most important determinants of the costs.

5.1 Climat

5.2 Topographie

Indiquez si la Technologie est spécifiquement appliquée dans des:

• situations concaves

Commentaires et précisions supplémentaires sur la topographie:

Landforms: Hill slopes-footslopes (mostly on concave slope segments)

5.3 Sols

5.4 Disponibilité et qualité de l'eau

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

Ground water table: >50m (There is a lowering of groundwater table due to overexploitation for irrigation purposes)
Availability of surface water: Poor/none (excess: sporadically there are flash floods during extreme rainfall events)
Water quality (untreated): For agricultural use only (irrigation) (groundwater)

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: Traditionally most agriculture is done by men in this region.

Population density: 10-50 persons/km2

Annual population growth: < 0.5%

15% of the land users are rich and own 20% of the land.
80% of the land users are average wealthy and own 75% of the land.
5% of the land users are poor and own 5% of the land.

Off-farm income specification: There is no difference in the ones who apply the technology and those who don’t. Most farmers do have an off-farm income for example from hunting, work in a factory, or office.

5.7 Superficie moyenne des terres utilisées par les exploitants des terres 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 des terres:

• individuel

Droits d’utilisation de l’eau:

• individuel

Commentaires:

All cropland is privately owned. Some shrubland or forest is state property. Water use is organised by permits to water extraction from aquifers on individual basis. Water rights are provided and controlled by the Water authority of the Segura river basin (CHS).

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

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)

Changements climatiques progressifs

Changements climatiques progressifs

Commentaires:

The crop type is sensitive to changes in water availability under the semi arid conditions

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:

Implementation of the terraces is relatively expensive. Additionally planting of shrubs is also relatively expensive and requires a subsidy. Once installed, maintenance is not expensive and pays off because of less damage to fields and infrastructure.

6.5 Adoption de la Technologie

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

• 11-50%

Commentaires:

80% of land user families have adopted the Technology with external material support

Comments on acceptance with external material support: Terraces are traditionally widespread in the region. Most of them were installed without external support. Nowadays there are subsidies for construction and maintenance of vegetated strips and terraces.

20% of land user families have adopted the Technology without any external material support

There is no trend towards spontaneous adoption of the Technology

Comments on adoption trend: There is acceptance, but it is not growing. In some parts terraces are removed to make larger fields, and some new ones are also constructed. Recently installed subsidies may change this

6.7 Points forts/ avantages/ possibilités de la Technologie

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

7.1 Méthodes/ sources d'information

7.2 Références des publications disponibles

Titre, auteur, année, ISBN:

Garcia-Fayos, P. and Gasque, M., 2002. Consequences of a severe drought on spatial patterns of woody plants in a two-phase mosaic steppe of Stipa tenacissima L. Journal of Arid Environments, 52(2): 199-208.

Disponible à partir d'où? Coût?

internet

Titre, auteur, année, ISBN:

Hooke, J.M., 2006. Human impacts on fluvial systems in the Mediterranean region. Geomorphology, 79(3-4): 311-335.

Disponible à partir d'où? Coût?

internet

Titre, auteur, année, ISBN:

Kirkby, M.J., Bracken, L.J. and Shannon, J., 2005. The influence of rainfall distribution and morphological factors on runoff delivery from dryland catchments in SE Spain. CATENA, 62(2-3): 136-156.

Disponible à partir d'où? Coût?

internet

7.3 Liens vers les informations pertinentes en ligne

Titre/ description:

CARM 2008. Programa de Desarrollo Rural de la Región de Murcia 2007-2013 Tomo I. 508pp

URL:

http://www.carm.es/neweb2/servlet/integra.servlets.ControlPublico?IDCONTENIDO=4689&IDTIPO=100&RASTRO=c431$m1219