1.2 Contact details of resource persons and institutions involved in the assessment and documentation of the Technology

Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)

Programme d’Appui à l’agriculture Productive (GIZ / PROMAP)

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) - Germany

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

Misereor - Germany

1.3 Conditions regarding the use of data documented through WOCAT

When were the data compiled (in the field)?

01/07/2012

The compiler and key resource person(s) accept the conditions regarding the use of data documented through WOCAT:

Yes

2.1 Short description of the Technology

Definition of the Technology:

Hand-dug trenches contribute to the restoration of tree cover and prevention of water erosion on slopes.

2.2 Detailed description of the Technology

Description:

This technique is designed to restore communal land on slopes and highland pediments. It involves manually excavating trenches 3 to 3.5 m long and 0.6 m deep, spaced 4 m apart in staggered rows. This results in around 625 trenches per hectare. The excavated earth is piled downhill of the trenches, which are aligned perpendicular to the slope. In the middle of each trench, a 0.40 m high step is left on which the tree seedling is planted. The tree receives the water it needs from the trench where it collects.

Purpose of the Technology: The main purpose of this technique is to restore tree cover on degraded, unfertile land and prevent water erosion on slopes by reducing the flow of water that threatens land downstream. The trenches reduce gully erosion and pedimentation of areas with a fragile soil structure. Like all afforestation measures, in the medium term, this technique is effective in protecting the land against water and wind erosion. The shade provided by the trees also lowers the temperature of the soil and the infiltration of water in the hand-dug trenches contributes to groundwater recharge.
Areas restored using hand-dug trenches can subsequently be exploited to a limited extent in accordance with strict controls.

Establishment / maintenance activities and inputs: The technique is very labour intensive. Work must begin immediately after harvesting when the soil is still moist and workable. A protection and monitoring system is required to ensure that grazing animals do not damage the young trees. The mortality of trees after planting is relatively high (survival rate is about 60%), and dead trees must be replaced systematically during the first three years. Good community organisation is required.

Natural / human environment: Hand-dug trenches are particularly useful when rainfall is low, as they retain water and make it available to the trees growing in them. In years when rainfall is abundant or there are violent downpours, the young trees are protected, as they are planted on a raised step within the trench, although there is a risk of flooding in the event of very heavy rain.

2.3 Photos of the Technology

2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment

2.6 Date of implementation

If precise year is not known, indicate approximate date:

• 10-50 years ago

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• through projects/ external interventions

Comments (type of project, etc.):

Developed, implemented and disseminated as part of projects and programmes undertaken from the 1980s onwards to combat desertification and improve natural resource management. Implemented by German Development Cooperation (BMZ, GIZ, KfW) in Niger by projects e.g. PDRT (Projet de développement rural de Tahoua - Tahoua Rural Development Project)

3.1 Main purpose(s) of the Technology

• reduce, prevent, restore land degradation

3.2 Current land use type(s) where the Technology is applied

Comments:

Major land use problems (compiler’s opinion): water erosion (gully, sheet), wind erosion, degraded and infertile land

Nomadism: Yes

Semi-nomadism / pastoralism: Yes

Cut-and-carry/ zero grazing: Yes

Improved pasture: Yes

Mixed: (eg agro-pastoralism, silvo-pastoralism): Yes

Other grazingland: agropastoralism

Selective felling of (semi-) natural forests: Yes

Forest products and services: timber, fuelwood, fruits and nuts, grazing / browsing, other forest products / uses (honey, medical, etc.)

Type of cropping system and major crops comments: armers are mainly agropastoralists with some communities specialised on pure pastoralism

Constraints of common grazing land

Constraints of forested government-owned land or commons

3.3 Further information about land use

Water supply for the land on which the Technology is applied:

• rainfed

Comments:

Water supply: Also mixed rainfed - irrigated and post-flooding

Number of growing seasons per year:

• 1

Specify:

Longest growing period in days: 120; Longest growing period from month to month: August to October

Livestock density (if relevant):

1-10 LU /km2

3.4 SLM group to which the Technology belongs

• improved ground/ vegetation cover
• irrigation management (incl. water supply, drainage)

3.5 Spread of the Technology

Specify the spread of the Technology:

• evenly spread over an area

3.6 SLM measures comprising the Technology

3.7 Main types of land degradation addressed by the Technology

Comments:

Secondary types of degradation addressed: Et: loss of topsoil, Hg: change in groundwater / aquifer level

Main causes of degradation: soil management (Unadapted land use methods, reduced or abandoned fallow periods), crop management (annual, perennial, tree/shrub) (Neglect of fallow periods and crop rotation), droughts (due to heat waves), population pressure (rapidly growing population increasing pressure on land), land tenure (insecure access to land and collectively managed communal land), poverty / wealth (very poor population)

Secondary causes of degradation: deforestation / removal of natural vegetation (incl. forest fires) (deforestation through overgrazing and fire wood collection), over-exploitation of vegetation for domestic use (firewood collection), overgrazing (cattle, sheep and goats), change in temperature (Climate change: heat waves), change of seasonal rainfall (more variable onset of rains), Heavy / extreme rainfall (intensity/amounts) (more variable and intensive rains), wind storms / dust storms (frequent storms), floods (due to intensive rain storms), labour availability (some migration of men to nearby cities), education, access to knowledge and support services (high level of illiteracy)

3.8 Prevention, reduction, or restoration of land degradation

Specify the goal of the Technology with regard to land degradation:

• restore/ rehabilitate severely degraded land

Comments:

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

4.1 Technical drawing of the Technology

4.2 Technical specifications/ explanations of technical drawing

Trenches are manually excavated 3 to 3.5 m long and 0.6 m deep, spaced 4 m apart in staggered rows. This results in around 625 trenches per hectare. The excavated earth is piled downhill of the trenches, which are aligned perpendicular to the slope. In the middle of each trench, a 0.40 m high step is left on which the tree seedling is planted. The tree benefits from the water collected in the trench.

Technical knowledge required for field staff / advisors: moderate

Technical knowledge required for land users: low

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, control of concentrated runoff: drain / divert, improvement of ground cover, stabilisation of soil (eg by tree roots against land slides), increase of infiltration, increase / maintain water stored in soil, water harvesting / increase water supply

Secondary technical functions: increase in organic matter, increase in nutrient availability (supply, recycling,…), increase of groundwater level / recharge of groundwater, sediment retention / trapping, sediment harvesting, reduction in wind speed, increase of biomass (quantity), promotion of vegetation species and varieties (quality, eg palatable fodder)

Vegetative measure: planted in trench
Vegetative material: T : trees / shrubs, G : grass

Vegetative measure: Vegetative material: T : trees / shrubs, G : grass

Retention/infiltration ditch/pit, sediment/sand trap
Spacing between structures (m): 4
Depth of ditches/pits/dams (m): 0.6
Length of ditches/pits/dams (m): 3.5

Vegetation is used for stabilisation of structures.

4.3 General information regarding the calculation of inputs and costs

Specify currency used for cost calculations:

• US Dollars

4.4 Establishment activities

	Activity	Type of measure	Timing
1.	marking out the contour line	Structural
2.	laying out the trenches in staggered rows	Structural
3.	digging two rectangular microcatchments separated horizontally by a flat surface	Structural
4.	making a hole in the central area	Vegetative
5.	planting the seedlings	Vegetative
6.	sowing grass on the ridges	Vegetative

4.5 Costs and inputs needed for establishment

	Specify input	Unit	Quantity	Costs per Unit	Total costs per input	% of costs borne by land users
Labour	All the Labour	unit	1.0	220.76	220.76
Plant material	Seedlings	unit	1.0	41.55	41.55
Other	Transport of seedlings	unit	1.0	1.93	1.93
Total costs for establishment of the Technology					264.24

4.6 Maintenance/ recurrent activities

	Activity	Type of measure	Timing/ frequency
1.	A protection and monitoring system is required to ensure that grazing animals do not damage the young trees	Vegetative
2.	dead trees must be replaced systematically during the first three years	Vegetative

4.8 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

Other costs
• equipment, such as jumper bars, shovels and axes
• 625 tree seedlings
• 15 kg of grass seed
• cost of transporting 2 cartloads of seedlings
• 120 seedlings to replace dead trees.

5.1 Climate

5.2 Topography

Comments and further specifications on topography:

Altitudinal zone: 200 m a.s.l.

Landforms: Also footslopes and valley floors

5.3 Soils

If available, attach full soil description or specify the available information, e.g. soil type, soil PH/ acidity, Cation Exchange Capacity, nitrogen, salinity etc.

Soil fertility is very low - medium

Soil drainage / infiltration is poor - medium

Soil water storage capacity is low - medium

5.4 Water availability and quality

Comments and further specifications on water quality and quantity:

Ground water table: > 10m

Availability of surface water: Surface runoff generated by limited but intense rainfalls

5.5 Biodiversity

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Population density: 10-50 persons/km2

Annual population growth: 3% - 4%

(mostly poor households below poverty line).

Off-farm income specification: men migrate temporarily or permanently to cities for off-farm income, women and men seasonally carry out paid farm work

Market orientation of production system: Most households crop for subsistence , but surplus is sold on the market. Some vegetable growing is just for commercial/ market.

Level of mechanization: Oxes and donkeys used for animal traction.

5.7 Average area of land owned or leased by land users applying the Technology

5.8 Land ownership, land use rights, and water use rights

Land ownership:

• state
• communal/ village

• not titled

Land use rights:

• individual

Comments:

Traditional land use rights prevail. On fields individual land use rights, communal rights on pasture and forest land (collection of wood and other products (fruits, medicinal plants))

5.9 Access to services and infrastructure

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Income and costs

Socio-cultural impacts

Ecological impacts

Water cycle/ runoff

Soil

Biodiversity: vegetation, animals

Climate and disaster risk reduction

6.2 Off-site impacts the Technology has shown

6.3 Exposure and sensitivity of the Technology to gradual climate change and climate-related extremes/ disasters (as perceived by land users)

Gradual climate change

Gradual climate change

	Season	Type of climatic change/ extreme	How does the Technology cope with it?
annual temperature		increase	well

Climate-related extremes (disasters)

Meteorological disasters

	How does the Technology cope with it?
local rainstorm	not well
local windstorm	well

Climatological disasters

	How does the Technology cope with it?
drought	well

Hydrological disasters

	How does the Technology cope with it?
general (river) flood	not well

Other climate-related consequences

Other climate-related consequences

	How does the Technology cope with it?
reduced growing period	not known

Comments:

Damages are generally small but need to be repaired quickly.

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?

Comments:

Establishment of the trenches involves considerable labour and growth of trees takes a couple of years.

6.5 Adoption of the Technology

Of all those who have adopted the Technology, how many have did so spontaneously, i.e. without receiving any material incentives/ payments?

• 0-10%

Comments:

Comments on acceptance with external material support: The technology has been applied by PDRT on common land using food/cash for work in order to inject money and food into the local communities.

Comments on spontaneous adoption: There was no spontaneous adoption. The technology is designed for common lands and takes considerable labour that only very well organised communities are able to mobilise.

There is no trend towards spontaneous adoption of the Technology

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
The young trees are protected of flooding, as they are planted on a raised step within the trench

Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
Hand-dug trenches retain water and make it available to the trees growing in them. Although the trenches are progressively filled with sediment, which reduces their capacity to retain water, at the same time, the trees develop and become less dependent on stored water.
This technique has proved effective in restoring forest/rangeland sites. The progressive development of grass and tree cover continues on the improved sites, where the tree population is up to 20 years old. After around ten years, the average annual production of wood is 1.3 steres per hectare.
The shade provided by the trees also lowers the temperature of the soil.
In the medium term, this technique is effective in protecting the land against water and wind erosion.
Areas restored using hand-dug trenches can subsequently be exploited to a limited extent in accordance with strict controls.

6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them

Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view	How can they be overcome?
The technique is very labour intensive. Work must begin immediately after harvesting when the soil is still moist and workable.	Good community organisation is required.
A protection and monitoring system is required to ensure that grazing animals do not damage the young trees. The mortality of trees after planting is relatively high (survival rate is about 60%), and dead trees must be replaced systematically during the first three years.

7.3 Links to relevant information which is available online

Title/ description:

Good Practices in Soil and Water Conservation. A contribution to adaptation and farmers´ resilience towards climate change in the Sahel. Published by GIZ in 2012.

URL:

http://agriwaterpedia.info/wiki/Main_Page