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

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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)

2.1 Short description of the Technology

Definition of the Technology:

Silt fences together with brush packing were introduced to reduce sediment transport and restoration of gully erosion in the Potlake nature reserve, Limpopo Province, South Africa.

2.2 Detailed description of the Technology

Description:

Silt fences, together with brush packing were introduced in the Potlake Game Reserve (2817 ha) in the Limpopo Province of South Africa to rehabilitate areas affected by serious rill and gully erosion. Due to overgrazing on highly erodible soils, gully headcuts are actively migrating upstream. Implementation of the technology leads to enhanced vegetation cover and reduced sediment transport in the gullies. Silt fences are temporary structures and are therefore placed closer together than permanent structures. The placing is such that the silt from the downstream structure builds up against the upstream structure to delay the perishing of the restoration materials. Vegetation must be established in the gully (donga) as soon as possible so that, when the materials decay after about ten years, the area will be restored. Altitudes vary from 1 174 m to 780 m above sea level. The reserve is located in a summer rainfall region and receives an average annual rainfall of 438 mm per year. Clayey duplex soils are prone to both natural and man-induced erosion. The vegetation comprises Central Bushveld vegetation units of the Savanna Biome. Savanna is characterized by a herbaceous layer (usually dominated by grasses) with a woody component. In Southern Africa, Bushveld is an apt description of the vegetation structure, as the vegetation most often does not comprise distinct shrub and tree layers. Instead, the shrubs and trees occur in a matrix with a grass-dominated herb layer. A number of large gullies exist along drainage lines on highly erodible soils. Some of the gullies are up to 1.5 m deep and 5 m wide. A total of around 200 m of silt fences were erected at selected sites in the reserve to retain sediment and to establish vegetation. The following steps were followed in the establishment of the silt fences:
1. Identification of priority sites to erect the silt fences - using Google Earth imagery and field surveys.
2. Acquisition of restoration material and training of local community members on the implementation of the technology (training by Mr. Buckle at that stage from the Department).
3. Levelling of the area where fences would be erected.
4. Construction of fences.
5. Brush packing (upstream of fence) stone packing (downstream in the gully).

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:

• less than 10 years ago (recently)

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• through projects/ external interventions

3.1 Main purpose(s) of the Technology

• reduce, prevent, restore land degradation
• conserve ecosystem
• protect a watershed/ downstream areas – in combination with other Technologies

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

Land use mixed within the same land unit:

No

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)

Land use mixed within the same land unit:

No

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
• cross-slope measure

3.6 SLM measures comprising the Technology

3.7 Main types of land degradation addressed by the Technology

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

4.1 Technical drawing of the Technology

4.2 General information regarding the calculation of inputs and costs

Specify how costs and inputs were calculated:

• per Technology unit

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 =:

16.0

4.3 Establishment activities

	Activity	Timing (season)
1.	Preparation of the site to be restored	Winter (outside raining season)
2.	Installation of silt fences followed by brush and stone packing	Winter

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	6.0	280.0	1680.0
Equipment	Power tools - electric power generator, angle grinder, hammer drill,	Per day	3.0	500.0	1500.0
Equipment	Measuring tape, wire tensioning tool, pole driver, heavy and light hammers, pick, spade, pliers and scissors	Per day	10.0	20.0	200.0
Construction material	4mm wire	Per meter	100.0	15.0	1500.0
Construction material	Standards	Per piece	6.0	90.0	540.0
Construction material	Netting	Per meter	15.0	90.0	1350.0
Construction material	Anchor poles	Per piece	6.0	10.0	60.0
Construction material	T pegs	Per piece	20.0	20.0	400.0
Construction material	Binding wire	Per kg	5.0	40.0	200.0
Construction material	Filter material (UV treated shade cloth - 80%)	Per meter	86.0	20.0	1720.0
Total costs for establishment of the Technology					9150.0
Total costs for establishment of the Technology in USD					571.88

If land user bore less than 100% of costs, indicate who covered the remaining costs:

Department of Forestry, Fisheries and the Environment - South Africa

4.5 Maintenance/ recurrent activities

	Activity	Timing/ frequency
1.	Repair of fences after floods	After flooding event

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	Repair of fences	Per day	2.0	280.0	560.0
Equipment	Pliers, hammers, wire tensioning tool, pick, spade, pliers and scissors	Per day	5.0	20.0	100.0
Construction material	Binding wire and filter material	Per meter	4.0	150.0	600.0
Total costs for maintenance of the Technology					1260.0
Total costs for maintenance of the Technology in USD					78.75

If land user bore less than 100% of costs, indicate who covered the remaining costs:

Department of Forestry, Fisheries and the Environment

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

1. Timing - during the raining season these areas could be inaccessible due to clayey soils and water in gullies.
2, Availability of labour.

5.1 Climate

5.2 Topography

Indicate if the Technology is specifically applied in:

• concave situations

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.

A variety of soil forms occur in the reserve and can generally be grouped according to the vegetation unit it supports. Sekhukhune Mountain Bushveld soils are predominantly shallow, rocky and clayey, with lime soils of the Glenrosa and Mispah soil forms often occurring in low-lying areas. Steep slopes commonly have rocky areas with no soil. The Dwars River valley is characterised by prismacutanic horizons with melanic structured diagnostic horizons.

Sekhukhune Plains Bushveld mainly occurs on red apedal clayey soils rich in metals. Soils on the plains are characterised by deep loamy Valsrivier soils. Shallow Glenrosa soils are found on the low-lying, rocky hills. Small mountains commonly have erodible black, melanic structured horizons.

5.4 Water availability and quality

Is water salinity a problem?

No

Is flooding of the area occurring?

Yes

5.5 Biodiversity

Comments and further specifications on biodiversity:

Although the reserve has a very high biodiversity it also includes a potential 16 plant species of conservation concern, of which one is critically endangered and two are endangered.
The reserve has a fair representation of game for its size, but it should be noted that the area is very prone to erosion if its ecological capacity is exceeded. During an aerial census conducted in the reserve a total of 582 head of game was recorded. There are currently 78 verified avian species occurring at the reserve, of which 10 occur on the IUCN Red List of Threatened Species. A total of 33 reptile species has been recorded and a possible 32 amphibian species. No data is currently available for the fish species occurring at the reserve.

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Nature reserve - tourism

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:

• state

• State land

• State land

Are land use rights based on a traditional legal system?

No

5.9 Access to services and infrastructure

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Other socio-economic impacts

Ecological impacts

Soil

Specify assessment of on-site impacts (measurements):

The on-site impact assessment mainly includes a visual assessment of the amount of sediment trapped behind the silt fences and the establishment of vegetation.

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)

Climate-related extremes (disasters)

Meteorological disasters

	How does the Technology cope with it?
local thunderstorm	moderately

Hydrological disasters

	How does the Technology cope with it?
flash flood	moderately

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

• 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?

No

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
Very important to stabilise landscapes.
Helps to improve the habitat for wildlife, biodiversity in the protected area.

Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
Helps to improve the habitat for wildlife, biodiversity in the protected area.

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?
Sensitive to floods	Timing of construction crucial - ready before the floods occur

Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view	How can they be overcome?
Same as above

7.1 Methods/ sources of information

7.2 References to available publications

Title, author, year, ISBN:

Combating erosion with silt fences, Jan van Heerden, 2006, ISBN 1-919849-76-9

Available from where? Costs?

https://www.arc.agric.za/arc-iae/Documents/Publication%20List%20and%20Orderform.pdf

Title, author, year, ISBN:

Five-year strategic plan for the Potlake Nature Reserve, Limpopo Province, South Africa

Available from where? Costs?

LEDET - no cost