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

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

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

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

1.3 Conditions regarding the use of data documented through WOCAT

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

Yes

1.4 Declaration on sustainability of the described Technology

Is the Technology described here problematic with regard to land degradation, so that it cannot be declared a sustainable land management technology?

No

2.1 Short description of the Technology

Definition of the Technology:

Retention ditches, also called infiltration ditches, are larger ditches designed to catch and retain all incoming runoff for infiltration into the soil.

2.2 Detailed description of the Technology

Description:

Retention ditches, also called infiltration ditches, are larger ditches designed to catch and retain all incoming runoff for infiltration into the soil. They operate like contour furrows, increasing the supply of water made available to crops planted in and adjacent the ditch, while also reducing soil erosion. However, they handle much more water. Retention ditches are in essence water harvesting and conservation structures

Purpose of the Technology: They are commonly used as an alternative to diversion ditches if there is no places to discharge runoff or if there is a need , as in semi –arid areas , to harvest water , e.g. for bananas.

Establishment / maintenance activities and inputs: When constructing the ditches, the soil is thrown to the lower side to form an embankment that prevents soil from falling back in. This structure can be stabilized further by planting grass on it. On soils with lower infiltration rate, or on slopes, the ends can be left open to allow excess water to drain out.

Natural / human environment: Retention ditches are normally constructed on relatively flat areas with closed ends and wide and deep enough to hold all the runoff expected. They are often found on steep slopes in humid area under small scale farming where there is no opportunity to discharge runoff to a waterway. Retentions ditches can be useful where soils are permeable, deep and stable. However, retention ditches are not recommended for areas with shallow soil, those prone to land slides or where soil salinity is a possibility.

2.3 Photos of the Technology

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

Country:

Kenya

Region/ State/ Province:

Eastern

Further specification of location:

Mbeere

Specify the spread of the Technology:

• evenly spread over an area

If precise area is not known, indicate approximate area covered:

• < 0.1 km2 (10 ha)

Comments:

Retention ditches technology not practiced by many farmers although some collaborate with the local agricultural extension officer from the ministry of Agriculture to show them the guidelines of construction.

Map

×

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 land users' innovation

3.1 Main purpose(s) of the Technology

• improve production
• reduce, prevent, restore land degradation
• create beneficial economic impact

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

Cropland

• Annual cropping
• Perennial (non-woody) cropping

Perennial (non-woody) cropping - Specify crops:

• banana/plantain/abaca

Comments:

Major land use problems (compiler’s opinion): To reduce soil erosion and retain runoff for infiltration.
Major land use problems (land users’ perception): Inadequate water for irrigating the farm.
Future (final) land use (after implementation of SLM Technology): Cropland: Ca: Annual cropping

3.3 Has land use changed due to the implementation of the Technology?

Has land use changed due to the implementation of the Technology?

• No (Continue with question 3.4)

3.4 Water supply

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

• mixed rainfed-irrigated

3.5 SLM group to which the Technology belongs

• water harvesting
• irrigation management (incl. water supply, drainage)
• water diversion and drainage

3.6 SLM measures comprising the Technology

structural measures

• S4: Level ditches, pits

3.7 Main types of land degradation addressed by the Technology

water degradation

• Hs: change in quantity of surface water

Comments:

Main causes of degradation: soil management, Heavy / extreme rainfall (intensity/amounts), poverty / wealth, labour availability
Secondary causes of degradation: deforestation / removal of natural vegetation (incl. forest fires)

3.8 Prevention, reduction, or restoration of land degradation

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

• prevent land degradation
• restore/ rehabilitate severely degraded land

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

A technical drawing showing a retention ditch. The run-off ponds within the ditch giving it time to infiltrate.

Location: Ntharawe. Eastern Province
Date: 27/10/2012

Technical knowledge required for field staff / advisors: moderate (In implement this technology the farmers collaborates with an Agriculture extension officer in order to assist in making the retention ditches.)
Technical knowledge required for land users: low (Water scarcity triggers farmers to look for better means of soil conservation and retention ditch plays an important role to satisfy crop water requirement.)

Main technical functions: control of concentrated runoff: retain / trap, increase of infiltration
Secondary technical functions: control of concentrated runoff: impede / retard, reduction of slope angle

Retention/infiltration ditch/pit, sediment/sand trap
Vertical interval between structures (m): 6
Spacing between structures (m): 30
Depth of ditches/pits/dams (m): 0.5
Width of ditches/pits/dams (m): 0.5
Length of ditches/pits/dams (m): 50
Height of bunds/banks/others (m): 0.5
Width of bunds/banks/others (m): 0.5
Length of bunds/banks/others (m): 50

Author:

Paul Kahiga, 8444-00300 Nairobi

4.2 General information regarding the calculation of inputs and costs

other/ national currency (specify):

Kshs

If relevant, indicate exchange rate from USD to local currency (e.g. 1 USD = 79.9 Brazilian Real): 1 USD =:

100.0

4.3 Establishment activities

4.4 Costs and inputs needed for establishment

4.5 Maintenance/ recurrent activities

4.6 Costs and inputs needed for maintenance/ recurrent activities (per year)

Comments:

in the month of June 2012

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

slope of the land, labour and availability of a technical person to assist in laying down of the contours

5.1 Climate

5.2 Topography

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: Medium
Soil drainage/infiltration: Medium
Soil water storage capacity: Medium

5.4 Water availability and quality

5.5 Biodiversity

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Land users applying the Technology are mainly common / average land users
Population density: 10-50 persons/km2
Annual population growth: 0.5% - 1%

5.7 Average area of land used by land users applying the Technology

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

Land ownership:

• individual, titled

Land use rights:

• individual

Water use rights:

• individual

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

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

Climate-related extremes (disasters)

Climatological disasters

Comments:

stabilization of the up-slope using grass which is also fed to animals

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)?

6.5 Adoption of the Technology

Comments:

There is a moderate trend towards spontaneous adoption of the Technology

6.7 Strengths/ advantages/ opportunities of the Technology

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

7.1 Methods/ sources of information