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Technologies
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Pitting to restore degraded catchment of Mount Fletcher Dam [South Africa]

Pits

technologies_3377 - South Africa

Completeness: 88%

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:

Buckle Jacob

Department of Environmental Affairs - South Africa

South Africa

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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

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

1.5 Reference to Questionnaire(s) on SLM Approaches (documented using WOCAT)

2. Description of the SLM Technology

2.1 Short description of the Technology

Definition of the Technology:

To improve infiltration and vegetation cover, by creating small pits on bare soil, which capture runoff and reduce erosion.

2.2 Detailed description of the Technology

Description:

This project on pitting was implemented on the banks of the Mount Fletcher dam in the Eastern Cape of South Africa. The rehabilitation was funded by the Department of Environmental Affairs as part of the “Working on Ecosystems” programme. The programme also focuses on creating jobs and improving skill levels within local communities. The average annual rainfall in the area is 600 to 800 mm and occurs mainly in summer as thunderstorms. Severe sheet and rill erosion occur in the dam’s catchment. Combined with overgrazing and veld fires on the highly erodible soils, the catchment is severely degraded. Due to the degradation, high loads of sediment have resulted in severe siltation of the Mount Fletcher dam. The pitting technology can help. It is suitable for any low gradient, degraded, landscape as long as duplex soils are not present - due to piping on these soils. The main purpose of pitting is to enhance infiltration of runoff water by capturing, and ponding, it on capped/crusted bare soils. Simultaneously soil loss, due to sheet and rill erosion, is reduced. Secondary benefits of ponding runoff include trapping of sediment and subsequent improvement of vegetation cover. Pitting is combined with brush packing (laying cut bush on the soil’s surface) or mulching, and the construction of silt fences (low barriers across the slope) to further improve sediment trapping. This technology commences with the digging of small pits (70 cm surface diameter and 30 cm deep ) by hand or mechanical implements. The excavated soil is piled up to form a ridge on the down-slope. Pits are placed 2 meters apart in rows 1 meter apart. Re-seeding in pits with commercially available grass seed mixes can be used to enhance vegetation cover. Brush packing over the ponds with local woody (preferably thorny branches) material is recommended (if available locally) to provide protection against grazing and to create a micro-climate for vegetation growth. In between and above the pits silt fences or fiber rolls (can be used to slow water runoff (placed 10 m apart, across the slope).
Silt fences and fiber rolls are temporary sediment control devices used on rehabilitation sites to reduce sediment movement downhill. A typical fence consists of a piece of synthetic filter fabric (also called a geotextile) stretched between a series of wooden or metal fence stakes along a horizontal contour level. A fiber roll is made of wood fiber, straw, coconut fiber or similar material formed into a tubular roll also fixed by wooden or metal stakes.
Maintenance of the structures will include the creation of more pits and repair of silt fences and/or fiber rolls where needed. Further brush packing might be required after 6 months.

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:

South Africa

Region/ State/ Province:

Eastern Cape

Further specification of location:

Near the town of Mount Fletcher on the banks of the Mount Fletcher dam

Specify the spread of the Technology:
  • evenly spread over an area
If precise area is not known, indicate approximate area covered:
  • 0.1-1 km2

2.6 Date of implementation

Indicate year of implementation:

2016

2.7 Introduction of the Technology

Specify how the Technology was introduced:
  • through projects/ external interventions

3. Classification of the SLM Technology

3.1 Main purpose(s) of the Technology

  • improve production
  • reduce, prevent, restore land degradation
  • conserve ecosystem
  • protect a watershed/ downstream areas – in combination with other Technologies
  • reduce risk of disasters
  • create beneficial economic impact

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

Grazing land

Grazing land

Extensive grazing:
  • Semi-nomadic pastoralism
Animal type:
  • cattle - dairy
  • goats
  • sheep
Products and services:
  • meat
  • milk
Comments:

Main animal species and products: Cattle, goats and sheep - meat and milk

Number of growing seasons per year: 1
Livestock density: Low

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

  • pastoralism and grazing land management
  • improved ground/ vegetation cover
  • surface water management (spring, river, lakes, sea)

3.6 SLM measures comprising the Technology

vegetative measures

vegetative measures

  • V2: Grasses and perennial herbaceous plants
structural measures

structural measures

  • S4: Level ditches, pits
  • S11: Others
management measures

management measures

  • M2: Change of management/ intensity level
Comments:

Other structural measures include brush packing (or mulch if available) and the placement of silt fences

3.7 Main types of land degradation addressed by the Technology

soil erosion by water

soil erosion by water

  • Wt: loss of topsoil/ surface erosion
  • Wo: offsite degradation effects
physical soil deterioration

physical soil deterioration

  • Pk: slaking and crusting

3.8 Prevention, reduction, or restoration of land degradation

Specify the goal of the Technology with regard to land degradation:
  • reduce land degradation
  • restore/ rehabilitate severely degraded land

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):

Pitting can be used to restore degraded bare landscapes on slopes up to 30 percent, though not on highly erodible duplex soils. The pits are dug 30 cm deep, with a surface diameter of 70 cm, and sited 2 m apart in rows 1 meter apart. Silt fences or fiber rolls are located 10 m apart across the slope. Brush packing is recommended for protection.

Author:

K. Coetzee

Date:

2005

4.2 General information regarding the calculation of inputs and costs

Specify how costs and inputs were calculated:
  • per Technology area
Indicate size and area unit:

2 hectares

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 =:

12.0

Indicate average wage cost of hired labour per day:

140 (excluding transport)

4.3 Establishment activities

Activity Timing (season)
1. Dig pits (5000/2ha) 2 to 3 months before onset of summer rains
2. Install silt fences or fibre rolls 2 to 3 months before onset of summer rains
3. Add grass seed mix in ponds and cover with layer of soil 2 to 3 months before onset of summer rains
4. Brush packing between pits 2 to 3 months before onset of summer rains

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
Labour Unskilled labour (including transport) per day 160.0 240.0 38400.0
Equipment Picks, spades, hand compactor, pliers, hopper, bow saws, hammer, wheel barrow (renting the equipment) per day 14.0 20.0 280.0
Plant material Grass seed kilogram 2.0 75.0 150.0
Construction material Silt fences or fibre rolls per meter 2000.0 15.0 30000.0
Construction material 1.0
Total costs for establishment of the Technology 68830.0
Total costs for establishment of the Technology in USD 5735.83
If land user bore less than 100% of costs, indicate who covered the remaining costs:

Department of Environmental Affairs - South Africa

4.5 Maintenance/ recurrent activities

Activity Timing/ frequency
1. Add more ponds if necessary After floods
2. Restore silt fences After floods
3. Brush packing of ponds After 6 months

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
Labour Unskilled labour per day 6.0 240.0 1440.0
Equipment Picks, spades, hand compactor, pliers, hopper, bow saws, hammer, wheel barrow (renting the equipment) per day 6.0 20.0 120.0
Plant material Grass seed kilogram 0.5 75.0 37.5
Construction material Silt fences per meter 200.0 15.0 3000.0
Total costs for maintenance of the Technology 4597.5
Total costs for maintenance of the Technology in USD 383.13
If land user bore less than 100% of costs, indicate who covered the remaining costs:

Department of Environmental Affairs - South Africa

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

Labor availability, soil hardness, availability of material, transport 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
Specify average annual rainfall (if known), in mm:

750.00

Specifications/ comments on rainfall:

Summer thunderstorms

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.
Indicate if the Technology is specifically applied in:
  • concave situations

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):
  • medium (loamy, silty)
Soil texture (> 20 cm below surface):
  • medium (loamy, silty)
Topsoil organic matter:
  • low (<1%)

5.4 Water availability and quality

Ground water table:

< 5 m

Availability of surface water:

poor/ none

Water quality (untreated):

unusable

Is water salinity a problem?

No

Is flooding of the area occurring?

Yes

Regularity:

episodically

Comments and further specifications on water quality and quantity:

Steep slopes in the catchment with frequent high rainfall events contribute to high levels of sheet and rill erosion casing the siltation of the Mount Fletcher dam (affecting the usability of the water and storing capacity of the dam).

5.5 Biodiversity

Species diversity:
  • low
Habitat diversity:
  • low
Comments and further specifications on biodiversity:

Degraded grassland

5.6 Characteristics of land users applying the Technology

Sedentary or nomadic:
  • Sedentary
Market orientation of production system:
  • subsistence (self-supply)
Off-farm income:
  • less than 10% of all income
Relative level of wealth:
  • very poor
Individuals or groups:
  • groups/ community
Level of mechanization:
  • manual work
  • animal traction
Gender:
  • women
  • men
Age of land users:
  • middle-aged
  • elderly
Indicate other relevant characteristics of the land users:

Poor rural communities far from markets - very little goods and services

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

  • < 0.5 ha
  • 0.5-1 ha
  • 1-2 ha
  • 2-5 ha
  • 5-15 ha
  • 15-50 ha
  • 50-100 ha
  • 100-500 ha
  • 500-1,000 ha
  • 1,000-10,000 ha
  • > 10,000 ha
Is this considered small-, medium- or large-scale (referring to local context)?
  • medium-scale

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

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

5.9 Access to services and infrastructure

health:
  • poor
  • moderate
  • good
education:
  • poor
  • moderate
  • good
technical assistance:
  • poor
  • moderate
  • good
employment (e.g. off-farm):
  • poor
  • moderate
  • good
markets:
  • poor
  • moderate
  • good
energy:
  • poor
  • moderate
  • good
roads and transport:
  • poor
  • moderate
  • good
drinking water and sanitation:
  • poor
  • moderate
  • good
financial services:
  • poor
  • moderate
  • good

6. Impacts and concluding statements

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

fodder production

decreased
increased

fodder quality

decreased
increased

animal production

decreased
increased
Comments/ specify:

Initially, animals are not grazed on restored areas to allow vegetation recovery – but the long term impacts should be positive.

land management

hindered
simplified
Comments/ specify:

Brush packing is used to prevent animals from grazing on rehabilitated areas.

Water availability and quality

drinking water availability

decreased
increased
Comments/ specify:

Infiltration improves - less runoff

drinking water quality

decreased
increased
Comments/ specify:

Less sedimentation from runoff.

water availability for livestock

decreased
increased
Comments/ specify:

Infiltration improves - less runoff

Income and costs

farm income

decreased
increased
Comments/ specify:

Over the long-term farm income will increase - improved rangelands.

diversity of income sources

decreased
increased
Comments/ specify:

Jobs are created for community members.

Other socio-economic impacts

Job creation

Improved skills

Socio-cultural impacts

food security/ self-sufficiency

reduced
improved

SLM/ land degradation knowledge

reduced
improved
Comments/ specify:

Skill levels increased for some community members.

situation of socially and economically disadvantaged groups

worsened
improved
Comments/ specify:

Household income increased for some community members.

Ecological impacts

Water cycle/ runoff

water quantity

decreased
increased
Comments/ specify:

Less runoff

water quality

decreased
increased
Comments/ specify:

Less sedimentation from runoff.

surface runoff

increased
decreased
Soil

soil moisture

decreased
increased

soil cover

reduced
improved

soil loss

increased
decreased

soil accumulation

decreased
increased

soil crusting/ sealing

increased
reduced

soil organic matter/ below ground C

decreased
increased
Biodiversity: vegetation, animals

Vegetation cover

decreased
increased

biomass/ above ground C

decreased
increased

plant diversity

decreased
increased
Comments/ specify:

Improved species composition due to seeding in pits.

Climate and disaster risk reduction

flood impacts

increased
decreased
Comments/ specify:

Less runoff

fire risk

increased
decreased
Comments/ specify:

More biomass to burn (including fencing and fibre rolls)

micro-climate

worsened
improved
Comments/ specify:

Improved micro-climate due to brush packing.

6.2 Off-site impacts the Technology has shown

water availability

decreased
increased
Comments/ specify:

Impact only slightly positive due to the extent of the erosion problem in the catchment - more pitting necessary to have a larger impact on the Mount Fletcher dam.

downstream siltation

increased
decreased
Comments/ specify:

Same as above.

Specify assessment of off-site impacts (measurements):

Impact of ponding only slightly positive due the the extent of the erosion problem in the catchment - more ponding necessary to have a larger impact on the Mount Fletcher dam. The Mount Fletcher dam is currently severely silted and the off-site effects of ponding is difficult to quantify at this stage.

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 increase or decrease 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 thunderstorm moderately
Climatological disasters
How does the Technology cope with it?
drought not well
land fire not well
Hydrological disasters
How does the Technology cope with it?
flash flood not well

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?
Short-term returns:

slightly negative

Long-term returns:

slightly positive

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?
Short-term returns:

slightly negative

Long-term returns:

slightly positive

6.5 Adoption of the Technology

  • 11-50%
Of all those who have adopted the Technology, how many did so spontaneously, i.e. without receiving any material incentives/ payments?
  • 0-10%

6.6 Adaptation

Has the Technology been modified recently to adapt to changing conditions?

Yes

other (specify):

droughts

Specify adaptation of the Technology (design, material/ species, etc.):

Adapted grass seed mixes for better drought tolerance.

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
Cost effective technology that can be applied to large areas (part of Extended Public Works Programme – job creation).
Improve infiltration of runoff.
Improve vegetation cover and therefore productivity of livestock.
Help to reduce the poverty level of communities and improve skill levels.
Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
Cost effective technology that can be applied to large areas.
Improve infiltration of runoff.
Improve vegetation cover and therefore productivity of livestock.
Help to reduce the poverty level of communities and improve skill levels.

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?
Silt fences can be damaged by fire and vandalism. Fire breaks and community engagement.
Very little local woody material for brush packing. Replace brush packing with mulch from nearby areas (can be expensive due to transport).
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view How can they be overcome?
Silt fences can be damaged by fire and vandalism. Fire breaks and community engagement.
Very little local woody material for brush packing. Replace brush packing with mulch from nearby areas (can be expensive due to transport).

7. References and links

7.1 Methods/ sources of information

  • interviews with SLM specialists/ experts
When were the data compiled (in the field)?

18/01/2018

7.2 References to available publications

Title, author, year, ISBN:

Wetland Rehabilitation Guidelines, W Russel, 2009, ISBN 978-1-77005-640-4: Water Research Commission - South Africa - WRC report TT 341/09

Available from where? Costs?

Water Research Commission - South Africa

Title, author, year, ISBN:

Caring for Natural Rangelands, Ken Coetzee, 2005, ISBN 1-86914-071-0

Available from where? Costs?

Ken Coetzee, University of KwaZulu-Natal Press

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