Technologies

Check Dam [China]

Lan Sha Ba

technologies_1365 - China

Completeness: 67%

1. معلومات عامة

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

Key resource person(s)

SLM specialist:

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:

نعم

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

Check Dam
approaches

Check Dam [China]

Check dam is a kind of sediment storage dam of 5m below and is built in channels to control the down cutting of channel bed.

  • Compiler: Haiyan WEI

2. Description of the SLM Technology

2.1 Short description of the Technology

Definition of the Technology:

Check dam refers to dam that constructed in the gullies or river ways and the height of the dam is often lower than 5m.

2.2 Detailed description of the Technology

Description:

Check dams are built in the gully systems to harvest water and sediment. Usually many check dams are built in a gully or waterway to control the gully erosion. Check dams can be classified into "masonry dam", "check dam of earth", "check dam with willow" according to materials. Some strong masonry can last more than 10 years. As willow pegs in the "check dam with willow" can grow into timber after years.
Maintenance work should be done before rainy seasons every year so as to prevent the dam from destruction.
Following are the building procedures:

Masonry dam & check dam using earth:
1. Preparation---Removing grass, roots and surface soil; Digging a channel along an axis of a check dam in order to combine the dam and the bed firmly.
2. Construction---If a dam is planned to be made of earth, do scarification first, then adding earth (about 0.3m thick) and ramming it into 0.2m layer by layer. Building the dam with stones and/or rocks.
3. Base---If a bed of a gully consists of earth or sand, "base" should be built at the downstream feet of the dam. Length of the base should be twice as that of the dam and thickness should be 50-70cm.
4. Building a spillway at the top of the dam.

Check dam with willow:
1. Removing grass, roots and surface soil.
2. Cutting branches from willow; chopping the branches into pegs with the thick ends wedge.
3. Inserting the pegs into the ground.
4. Entwining wattles from willows around the pegs compactly.
5. Filling the space between two rows of pegs with stones, bricks, treetops etc. Making the stuff surface 10cm lower than the pegtop.
6. Combining the dam into a whole with iron chains.

2.3 Photos of the Technology

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

بلد:

China

Region/ State/ Province:

Shanxi, Beijing

Specify the spread of the Technology:
  • evenly spread over an area
If the Technology is evenly spread over an area, specify area covered (in km2):

145,0

If precise area is not known, indicate approximate area covered:
  • 100-1,000 km2
Comments:

Total area covered by the SLM Technology is 145 km2.

As a traditional SWC technology, check dams have been used widely in China.

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.):

Experiences from the local people's many SWC practice.

3. Classification of the SLM Technology

3.1 Main purpose(s) of the Technology

  • reduce, prevent, restore land degradation

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

Land use mixed within the same land unit:

نعم

Specify mixed land use (crops/ grazing/ trees):
  • Agro-pastoralism (incl. integrated crop-livestock)

Cropland

Cropland

  • Annual cropping
Annual cropping - Specify crops:
  • cereals - maize
  • cereals - wheat (winter)
Number of growing seasons per year:
  • 1
Specify:

Longest growing period in days: 180Longest growing period from month to month: Apr - Sep

Grazing land

Grazing land

Waterways, waterbodies, wetlands

Waterways, waterbodies, wetlands

  • Ponds, dams
Main products/ services:

Check Dam

Comments:

Major land use problems (compiler’s opinion): Serious gully erosion by water.

Major land use problems (land users’ perception): Gullies were widened and deepened greatly in the rainy season and crop land area is decreasing above the gully edges.

Constraints of urban land use

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

  • surface water management (spring, river, lakes, sea)
  • reduce loss of cropland

3.6 SLM measures comprising the Technology

vegetative measures

vegetative measures

  • V1: Tree and shrub cover
structural measures

structural measures

  • S5: Dams, pans, ponds
Comments:

Main measures: structural measures

3.7 Main types of land degradation addressed by the Technology

soil erosion by water

soil erosion by water

  • Wg: gully erosion/ gullying
Comments:

Main type of degradation addressed: Wg: gully erosion / gullying

Main causes of degradation: deforestation / removal of natural vegetation (incl. forest fires), poverty / wealth (Lack of captial)

Secondary causes of degradation: other natural causes (avalanches, volcanic eruptions, mud flows, highly susceptible natural resources, extreme topography, etc.) specify, education, access to knowledge and support services (Lack of knowledge), Lack of enforcement of legislat./authority

3.8 Prevention, reduction, or restoration of land degradation

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

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

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

Description of Building Check Dam Procedures

Location: the Loess Plateau. Shanxi, Beijing

Date: 2000

Technical knowledge required for field staff / advisors: moderate

Technical knowledge required for land users: moderate

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

Secondary technical functions: increase / maintain water stored in soil

Construction material (earth): Loessial earth

Construction material (stone): if available

Construction material (wood): willow pegs

Slope (which determines the spacing indicated above): 30%

If the original slope has changed as a result of the Technology, the slope today is: 16%

Lateral gradient along the structure: 90%

For water harvesting: the ratio between the area where the harvested water is applied and the total area from which water is collected is: 1:30

Author:

LIU Baoyuan, Beijing China

4.2 General information regarding the calculation of inputs and costs

other/ national currency (specify):

RMB Yuan

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

8,27

Indicate average wage cost of hired labour per day:

2.00

4.3 Establishment activities

Activity Timing (season)
1. Preparation
2. Construction Before rainy season

4.4 Costs and inputs needed for establishment

Comments:

Duration of establishment phase: 120 month(s)

4.5 Maintenance/ recurrent activities

Activity Timing/ frequency
1. reparing after rainstorm.

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

Comments:

Length, width and height of check dams.

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

Sizes and materials of the check dams.

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:

580,00

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
Comments and further specifications on topography:

Slopes on average also gentle, moderate and rolling

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)
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 fertility: low

Soil drainage / infiltration: medium

Soil water storage capacity: low

5.6 Characteristics of land users applying the Technology

Off-farm income:
  • 10-50% of all income
Relative level of wealth:
  • average
Level of mechanization:
  • animal traction
  • mechanized/ motorized
Indicate other relevant characteristics of the land users:

Population density: 100-200 persons/km2

Annual population growth: < 0.5%

30% of the land users are average wealthy and own 20% of the land (No difference).

Off-farm income specification: The land users who made the check dams can own more "deposited land". Generally these deposited land is fertile and produces high yield.

Level of mechanization: animal traction: on steep slope

Level of mechanization: mechanized/motorized: plateau or gully flat.

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

Land ownership:
  • state
Land use rights:
  • communal (organized)

6. Impacts and concluding statements

6.1 On-site impacts the Technology has shown

Ecological impacts

Water cycle/ runoff

surface runoff

increased
decreased
Quantity before SLM:

48

Quantity after SLM:

30

Soil

soil loss

increased
decreased
Quantity before SLM:

180

Quantity after SLM:

110

6.4 Cost-benefit analysis

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

positive

Long-term returns:

very positive

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

positive

Long-term returns:

very positive

6.5 Adoption of the Technology

  • > 50%
If available, quantify (no. of households and/ or area covered):

180 household are using the technology and represent 65 percent of the poeple living in the stated area

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

55% of land user families have adopted the Technology with external material support

150 land user families have adopted the Technology with external material support

Comments on acceptance with external material support: estimates

10% of land user families have adopted the Technology without any external material support

30 land user families have adopted the Technology without any external material support

Comments on spontaneous adoption: estimates

There is a little trend towards spontaneous adoption of the Technology

Comments on adoption trend: In the past (planning economy)SWC activities are administrative action to call local land users to carry out, but nowadays in the market economic conditions, if no or little benefits obtained, land users would not like to do any more.

7. References and links

7.1 Methods/ sources of information

7.2 References to available publications

Title, author, year, ISBN:

How to design the dry masonry dam in the Hanjiachuan watershed. Tianyuzhu, Wangzuliang. Beijing. Water conservation in Beijing.. 2000.3.

Available from where? Costs?

Library of the Resource and Environmental Department of the Beijing Normal Univ.

Title, author, year, ISBN:

Consideration about the check dam design and application. Liu shunzong. Soil and water conservation in China.. 1990.6.

Available from where? Costs?

Library of the Resource and Environmental Department of the Beijing Normal Univ.

Title, author, year, ISBN:

Special Planning of Soil and Water Conservation in Xinzhou Region, Shanxi Province. 1986-2000.

Available from where? Costs?

Library of the Resource and Environmental Department of the Beijing Normal Univ.

Title, author, year, ISBN:

The application of the Check dam with willow in controlling gully erosion.Tu xingwen. Soil and water conservation in China.. 1986.

Available from where? Costs?

Library of the Resource and Environmental Department of the Beijing Normal Univ.

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