Technologies

Earth dam for stockwater [South Africa]

technologies_1376 - South Africa

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Completeness: 61%

1. General information

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

Key resource person(s)

SLM specialist:

Jannie Nel

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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. Description of the SLM Technology

2.1 Short description of the Technology

Definition of the Technology:

Construction of earth dams to provide stock water

2.2 Detailed description of the Technology

Description:

Bulldozers were used to build earth dams and to move the soil to construct bankments and spillways in a river or natural run-off (water course of some kind). No concrete or rock is used, only soil up to a certain slope of sides or crests. The main concern is to provide water to seep through the spillway large enough to discharge the excess water from the catchment whenever the dam is full. Normally the spillway is constructed so that the water doesn’t cause erosion in the spillway itself.

Purpose of the Technology: The purpose was to catch water to provide stock water for animals in the rural areas (de-silt earth dam in 5-10 years time close to the village, dams far away in the veld silt up in a longer time).

Establishment / maintenance activities and inputs: Maintenance is done in winter when rain is not expected. All the dams are seasonal, water is only available for 2 months after the rainy season (June - September). Evaporation is very high, and cleaning up and fixing-up are necessary.

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

Country:

South Africa

Region/ State/ Province:

North West Province

Further specification of location:

Eastern Regions of North West

Specify the spread of the Technology:
  • applied at specific points/ concentrated on a small area
Comments:

Total area covered by the SLM Technology is 184 km2.

All farm cattle are communal. Ruighoek town the only big village in the area.

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2.6 Date of implementation

If precise year is not known, indicate approximate date:
  • more than 50 years ago (traditional)

2.7 Introduction of the Technology

Specify how the Technology was introduced:
  • as part of a traditional system (> 50 years)
Comments (type of project, etc.):

Comes from a need which people had

3. Classification of the SLM Technology

3.1 Main purpose(s) of the Technology

  • access to water

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

Grazing land

Grazing land

Extensive grazing:
  • Nomadism
Settlements, infrastructure

Settlements, infrastructure

  • Settlements, buildings
Comments:

Major land use problems (compiler’s opinion): Communal ownership system, grass belong to everybody - not one owner. Overgrazing as far the little boys (witch look after the cattle) can walk, in the rest undergrazing, no proper management, no knowledge, no infrastructure

Major land use problems (land users’ perception): Land doesn’t belong to him, can’t put infrastructure in (fence, water) for cattle farming.
Drought, fire (caused by human), some people still belief that veld get sweeter if it is burned each year

Nomadism: Yes

Number of growing seasons per year: 1
Longest growing period in days: 150; Longest growing period from month to month: Oct - Feb

3.5 SLM group to which the Technology belongs

  • water harvesting

3.6 SLM measures comprising the Technology

structural measures

structural measures

  • S5: Dams, pans, ponds

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: prevention of land degradation

4. Technical specifications, implementation activities, inputs, and costs

4.1 Technical drawing of the Technology

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Technical specifications (related to technical drawing):

Technical knowledge required for field staff / advisors: high

Main technical functions: water harvesting / increase water supply

Secondary technical functions: control of concentrated runoff: retain / trap, sediment retention / trapping, sediment harvesting

Grass species: Kikuyu grass or any natural grass

Vegetation is used for stabilisation of structures.

4.2 General information regarding the calculation of inputs and costs

other/ national currency (specify):

Rand

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

6.0

4.3 Establishment activities

Activity Timing (season)
1. No planting, it has to grow itself
2. Clearing the foundation 5 days (in winter)
3. Gather soil for the embankement (only good soil) 5 days (in winter)
4. Push the embanquement 2 weeks
5. Excavation of the spillways 1 week
6. Clearing of the basin, a little bit 2 days

4.4 Costs and inputs needed for establishment

Specify input Unit Quantity Costs per Unit Total costs per input % of costs borne by land users
Equipment Machine use for dam construction ha 1.0 6700.0 6700.0
Total costs for establishment of the Technology 6700.0
Total costs for establishment of the Technology in USD 1116.67

4.5 Maintenance/ recurrent activities

Activity Timing/ frequency
1. The cattle will eat it
2. Repairing the dam
3. Repairing the spillways 1-3 years
4. If dams is dry, take out the sediments Winter/1-3 years

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

Specify input Unit Quantity Costs per Unit Total costs per input % of costs borne by land users
Equipment Machine use for dam maintenance ha 1.0 835.0 835.0
Total costs for maintenance of the Technology 835.0
Total costs for maintenance of the Technology in USD 139.17
Comments:

Earth moving

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

Machine running cost

5. Natural and human environment

5.1 Climate

Annual rainfall
  • < 250 mm
  • 251-500 mm
  • 501-750 mm
  • 751-1,000 mm
  • 1,001-1,500 mm
  • 1,501-2,000 mm
  • 2,001-3,000 mm
  • 3,001-4,000 mm
  • > 4,000 mm
Specifications/ comments on rainfall:

Evaporation high

Agro-climatic zone
  • semi-arid

5.2 Topography

Slopes on average:
  • flat (0-2%)
  • gentle (3-5%)
  • moderate (6-10%)
  • rolling (11-15%)
  • hilly (16-30%)
  • steep (31-60%)
  • very steep (>60%)
Landforms:
  • plateau/plains
  • ridges
  • mountain slopes
  • hill slopes
  • footslopes
  • valley floors
Altitudinal zone:
  • 0-100 m a.s.l.
  • 101-500 m a.s.l.
  • 501-1,000 m a.s.l.
  • 1,001-1,500 m a.s.l.
  • 1,501-2,000 m a.s.l.
  • 2,001-2,500 m a.s.l.
  • 2,501-3,000 m a.s.l.
  • 3,001-4,000 m a.s.l.
  • > 4,000 m a.s.l.

5.3 Soils

Soil depth on average:
  • very shallow (0-20 cm)
  • shallow (21-50 cm)
  • moderately deep (51-80 cm)
  • deep (81-120 cm)
  • very deep (> 120 cm)
Soil texture (topsoil):
  • fine/ heavy (clay)
Topsoil organic matter:
  • medium (1-3%)
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 depth on average: In February

Soil fertility is high

Soil water storage capacity is very high

5.6 Characteristics of land users applying the Technology

Off-farm income:
  • > 50% of all income
Relative level of wealth:
  • poor
Indicate other relevant characteristics of the land users:

100% of the land users are poor and own 80% of the land (Communal farmers).

Off-farm income specification: Farming can't sustain the people

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

Land ownership:
  • communal/ village
Land use rights:
  • communal (organized)

6. Impacts and concluding statements

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

production area

decreased
increased

Ecological impacts

Water cycle/ runoff

water quantity

decreased
increased
Comments/ specify:

water harvesting

excess water drainage

reduced
improved

6.2 Off-site impacts the Technology has shown

downstream flooding

increased
reduced

downstream siltation

increased
decreased

6.5 Adoption of the Technology

Comments:

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
Water for animals

How can they be sustained / enhanced? More dams
Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
Runoff control in stream bed

How can they be sustained / enhanced? More dams
Add to under ground water supply

How can they be sustained / enhanced? More dams
Provide stock water

How can they be sustained / enhanced? More dams
Facilitate grazing rotation

How can they be sustained / enhanced? More dams

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

Weaknesses/ disadvantages/ risks in the land user’s view How can they be overcome?
Too small More dams
Too far More dams
Not enough More dams
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view How can they be overcome?
Animal trampling turns water to mud Fence off dam
Animal trampling decreases bank height Fence off dam
Fast sedimentation in eroded catchment areas Prevent erosion in catchment
Spreading of animals diseases Fence off dam
Dependant on rain Drill a bore hole

7. References and links

7.1 Methods/ sources of information

Links and modules

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