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)

Name of project 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

2.1 Short description of the Technology

Definition of the Technology:

Water harvesting and storage structures to impound runoff generated from upstream catchment areas.

2.2 Detailed description of the Technology

Description:

Small earth dams are water harvesting storage structures, constructed across narrow sections of valleys, to impound runoff generated from upstream catchment areas.

Establishment / maintenance activities and inputs: Construction of the dam wall begins with excavation of a core trench along the length of the dam wall which is filled with clay and compacted to form a ‘central core’ that anchors the wall and prevents or minimizes seepage. The upstream and downstream embankments are also built using soil with a 20-30% clay content. During construction – either by human labour, animal draught or machine (bulldozer, compacter, grader etc.) – it is critical to ensure good compaction for stability of the wall. It is common to plant Kikuyu grass (Pennisetum clandestinum) to prevent erosion of the embankment. The dam is fenced with barbed wire to prevent livestock from eroding the wall. Typical length of the embankment is 50-100 m with water depth ranging 4-8 m. An emergency spillway (vegetated or a concrete shute) is provided on either, or both sides, of the wall for safe disposal of excess water above the full supply level. The dam water has a maximum throwback of 500 m, with a capacity ranging from 50,000 – 100,000 m3.

Natural / human environment: The dams are mainly used for domestic consumption, irrigation or for watering livestock. If the dams are located on communal lands, their establishment requires full consultation and involvement of the local community. The government provides technical and financial assistance for design, construction and management of these infrastructures. Community contribution includes land, labour and local resources. The community carries out periodic maintenance of the infrastructure – including vegetation management on embankment, desilting etc. – and of the catchment areas (through soil and water conservation practices).

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:

Zambia

Region/ State/ Province:

Southern Province

Specify the spread of the Technology:

• applied at specific points/ concentrated on a small area

Comments:

In the study area there are over 293 dams serving a cattle population of 1.1 million and human population of nearly 1 million people

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 projects/ external interventions

3.1 Main purpose(s) of the Technology

• Access to water

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

Cropland

• Annual cropping

Number of growing seasons per year:

• 1

Specify:

Longest growing period in days: 120; Longest growing period from month to month: Nov-April

Comments:

Major land use problems (compiler’s opinion): water degradation, soil erosion, low surface water availability

3.4 Water supply

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

• rainfed

3.5 SLM group to which the Technology belongs

• improved ground/ vegetation cover
• water harvesting

3.6 SLM measures comprising the Technology

vegetative measures

• V2: Grasses and perennial herbaceous plants

structural measures

• S5: Dams, pans, ponds

Comments:

Secondary measures: vegetative measures

Type of vegetative measures: aligned: -contour

3.7 Main types of land degradation addressed by the Technology

soil erosion by water

• Wt: loss of topsoil/ surface erosion
• Wg: gully erosion/ gullying

Comments:

Secondary types of degradation addressed: Wg: gully erosion / gullying

Main causes of degradation: Heavy / extreme rainfall (intensity/amounts), floods

3.8 Prevention, reduction, or restoration of land degradation

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

• prevent land degradation
• reduce land degradation

Comments:

Secondary goals: rehabilitation / reclamation of denuded land

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

Dimensions and main components of a small dam: (1) water body; (2) dam wall (with layers of compacted soil; side slopes 3:1); (3) central core ('key'); (4) grass cover; (5) stone apron; (6) spillway

Southern Province

Technical knowledge required for field staff / advisors: high

Technical knowledge required for land users: high

Main technical functions: control of concentrated runoff: retain / trap, water harvesting / increase water supply

Aligned: -contour
Vegetative material: G : grass

Grass species: Pennisetum clandestinum

Dam/ pan/ pond
Depth of ditches/pits/dams (m): 4.00
Length of ditches/pits/dams (m): 50.00

Construction material (earth): 20-30% clay content

Specification of dams/ pans/ ponds: Capacity 100000.00m3

Dimensions of spillways: 5.00m

Vegetation is used for stabilisation of structures.

Author:

Mats Gurtner, Center for Development and Environment, University of Bern

4.2 General information regarding the calculation of inputs and costs

Specify how costs and inputs were calculated:

• per Technology unit

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:

Machinery/ tools: machinery, ox-ripper, hoe/pick, shovel

Establishment costs are calculated for a dam with an earthwork volume of 10’000 m3 (44 m long; 8 m deep; side slopes 3:1). 20% of costs are borne by the community (in-kind contribution: labour and local materials such as sand, stones). Construction machinery can include: tipper truck, bulldozer, motor scraper, compactor, tractor, grader

5.1 Climate

5.2 Topography

Comments and further specifications on topography:

Slopes on average: Gentle (plains), moderate (plains), rolling (plains) and hilly (valleys)

Altitudinal zone: Also 1000-1500 m a.s.l., range from 300-1200 m a.s.l.

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 medium

5.4 Water availability and quality

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Land users applying the Technology are mainly disadvantaged land users

Population density: < 10 persons/km2

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:

• communal/ village

• not titled

Land use rights:

• communal (organized)

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Water availability and quality

Income and costs

Socio-cultural impacts

Ecological impacts

Water cycle/ runoff

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

Climate-related extremes (disasters)

Meteorological disasters

Climatological disasters

Hydrological disasters

Other climate-related consequences

Other climate-related consequences

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:

Comments on adoption trend: Records of 1991 indicate at least 537 such dams exist in Zambia. In the study area there are over 293 dams serving a cattle population of 1.1 million and human population of nearly 1 million people.

6.7 Strengths/ advantages/ opportunities of the Technology

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

7.2 References to available publications

Title, author, year, ISBN:

Nissen-Petersen E. 2006. Water from small dams. A handbook for technicians, farmers and others on site investigations, designs, cost estimations, construction and maintenance of small earth dams

Title, author, year, ISBN:

Morris P. H. 1991. Statement of Policy: Progress Review of the Drought Relief Dam Cons/ruction Project, Southern Province. Part 1 — Main Report. Irrigation and Land Husbandry Branch, Department of Agriculture, Chôma

Title, author, year, ISBN:

Sichingabula H.M. 1997. Problems of sedimentation in small dams in Zambia. Human Impact on Erosion and Sedimentation (Proceedings of the Rabat Symposium, April 1997. IAHS Publ. no. 245, 1997

7.3 Links to relevant online information

Title/ description:

The Jesuit Centre for Theological Reflection. 2010. Social Conditions Programme.

URL:

http://www.mywage.org/zambia/main/minimum-wage/comparitive-minimum-wage