Technologies

Check dam for land [China]

淤地坝,谷坊

technologies_1455 - China

Completeness: 84%

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:
SLM specialist:

Mu Xingming

Institute of Soil and Water Conservation, CAS and MWR

China

SLM specialist:

Wen Zhongmin

Institute of Soil and Water Conservation, CAS and MWR

China

SLM specialist:
SLM specialist:

Chen Yun-ming

Institute of Soil and Water Conservation, CAS and MWR

China

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
Northwest A&F University (NWAFU) - China

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

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

Project of check-dam for land
approaches

Project of check-dam for land [China]

Approach of check dam for land is a kind of soil and water conservation activity to reduce the sediment discharge and improve the agricultural condition through building a dam across the valley in order to silt the sediment from upstream untill it convert to land with few soil erosion and ...

  • Compiler: Fei WANG

2. Description of the SLM Technology

2.1 Short description of the Technology

Definition of the Technology:

Check dam for land is a structural SLM practice that is constructed in the valley of a watershed in order to slow down the runoff and increase sedimentation. After this, the land quality of the controlling area will increase because soil and water conditions in this place are improved.

2.2 Detailed description of the Technology

Description:

The check dam is a small dam designed to reduce flow velocity, control soil erosion, and allow to settle on the bed of the valley. The whole system includes main body of dam, spillway, overflow and supporting measures. The check dam for land is a small dam mainly for land after it is filled up by the sediment from upstream area, from several years to 20 years in common, it could be flat land in the valley, not mainly for water collection (different from reservior).

Purpose of the Technology: Check dams in the Loess Plateau are very common. There are many advantages. The check dam could not only reduce the erosion of the gullies, furthermore it retain the sediment in the flow and this decreases the sediment of the Yellow River. The check dam is good quality land for the soils because of the sedimentation of organic matter and other nutrients from topsoil . In this region soils are deep and very fertile because most soil is from the top soil upstream. The soil moisture of check dam is also much better than in any other places in the watershed because the flood should go away from its surface and the water inflitration is great in raining seasons.

Establishment / maintenance activities and inputs: The establishment needs enough money because it has to be safe enough, and the maintenance cost is not so high. The catchment with great soil erosion is better when we considered the formation time of land.

Natural / human environment: The controlling area of check dam for land varies greatly from 30 square km or more. Since the "Grain for Green" Project of China in 1999, the soil erosion on the slope decreased. The time from reservoir to land need more time because there is less and less sediment from upstream and the sedimentation changed slowly.

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:

China

Region/ State/ Province:

Shaanxi Province

Further specification of location:

Yanhe River Basin

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

Boundary points of the Technology area: Only one check-dam for land is listed here.
Total area covered by the SLM Technology is 19.4 km2.

The total area with different measures is almost 2000 km2 . Yanhe River is a first class branch of Yellow River, China. The average channel slope is 3.26‰, and the area of whole basin is 7,687 km2. It is situated in the semi-arid North Temperate Zone with an average annual precipitation varying from 500 to 550 mm, and an average annual air temperature ranging from 8.5 to 11.4℃. It is in hilly gully area of the Loess Plateau covered by loess. The landform is broken seriously. The gully density (the length of channel in one km2) is amount to 2.1 to 4.6 km•km-2. The soil loss is severe all along.
The Ganguyi Hydrology Station (109°48′E, 36°42′N) located in the Ganguyi Town, Baota Country, Yan’an City, Shaanxi Province. The area up Ganguyi Hydrology Station is 5,891 km2, including of Jingbian County(256km2), Zhidan County(708km2), Ansai County(2,699km2) and Baota County(2,228km2). The average annual runoff is 0.22 billion m3, and the runoff modulus accounting for 4,776.36 m3•km-2•yr-1. The average annual sediment flow is 4.776 million tons, and the sediment flow modulus accounting for 8,100 t•km-2•yr-1. The coarse sediment (sediment particle diameter not less than 0.05 mm) flow modulus is 2,430 t•km-2•yr-1 on the Ganguyi Hydrology Station.

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:
  • during experiments/ research
Comments (type of project, etc.):

It is an old methodology in the Loess Plateau. Since 2003, the check dam had been determined as "Highlight Project " of the Ministry of Water Resources in order to expand in the whole area of the Yellow River Basin.

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:

Yes

Specify mixed land use (crops/ grazing/ trees):
  • Agro-silvopastoralism

Cropland

Cropland

  • Annual cropping
  • Tree and shrub cropping
Annual cropping - Specify crops:
  • cereals - maize
  • cereals - millet
  • flower crops
  • fodder crops - alfalfa
  • legumes and pulses - beans
  • oilseed crops - sunflower, rapeseed, other
  • root/tuber crops - potatoes
  • buckwheat
Tree and shrub cropping - Specify crops:
  • dates
  • pome fruits (apples, pears, quinces, etc.)
Specify:

Longest growing period in days: 300Longest growing period from month to month: March to NovemberSecond longest growing period in days: 200Second longest growing period from month to month: April to October

Waterways, waterbodies, wetlands

Waterways, waterbodies, wetlands

  • Ponds, dams
Comments:

major crop: beans, sunflower, apple, Chinese date, alfalfa, potato, millets, maize, buckwheat

Major land use problems (compiler’s opinion): Normally, the bed of valley is V-shaped and is covered by grass and trees. For the seasonal torrent or flash, it is very difficult to plant crops. The gully also cuts down by runoff and extends because of erosion's gravity .

Major land use problems (land users’ perception): It can not be used as agricultural purpose, especially to get more food.

Future (final) land use (after implementation of SLM Technology): Cropland: Ca: Annual cropping

Livestock is grazing on crop residues

3.3 Has land use changed due to the implementation of the Technology?

Has land use changed due to the implementation of the Technology?
  • Yes (Please fill out the questions below with regard to the land use before implementation of the Technology)
Cropland

Cropland

  • Annual cropping

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

  • cross-slope measure
  • surface water management (spring, river, lakes, sea)

3.6 SLM measures comprising the Technology

structural measures

structural measures

  • S5: Dams, pans, ponds
  • S11: Others
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
  • Wo: offsite degradation effects
Comments:

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

Secondary types of degradation addressed: Wo: offsite degradation effects

Secondary causes of degradation: Heavy / extreme rainfall (intensity/amounts) (It is the reason of erosion that influence the valley.)

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:

Main goals: prevention of land degradation

Secondary goals: mitigation / reduction of land degradation

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

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

The check dam land.

Location: Mazhuang Watershed. Baota County, Yan'an City, Shaanxi China

Date: 2008-10-20

Technical knowledge required for field staff / advisors: high (The design and construction need professional knowledge.)

Technical knowledge required for land users: low (it is easy to use, like alluvial land or wide terrace.)

Main technical functions: control of concentrated runoff: retain / trap

Spillway
Vertical interval between structures (m): 3
Spacing between structures (m): 6
Height of bunds/banks/others (m): 4
Width of bunds/banks/others (m): 6
Length of bunds/banks/others (m): 100

Dam/ pan/ pond
Vertical interval between structures (m): 10
Spacing between structures (m): 100
Depth of ditches/pits/dams (m): 10
Width of ditches/pits/dams (m): 50-100
Length of ditches/pits/dams (m): 300-1000

Construction material (earth): The earth-bank dam is built in Yanhe River Basin.

Construction material (stone): to build the spillways

Slope (which determines the spacing indicated above): 2-5%

If the original slope has changed as a result of the Technology, the slope today is: 2%

Lateral gradient along the structure: 2%

Specification of dams/ pans/ ponds: Capacity 180000m3

Catchment area: 58.3km2m2

Slope of dam wall inside: 30%;
Slope of dam wall outside: 60%

Dimensions of spillways: 3m

Vegetation is used for stabilisation of structures.

Author:

Wang Fei, Yangling, Shaanxi Province, China

4.2 General information regarding the calculation of inputs and costs

Specify currency used for cost calculations:
  • USD
If relevant, indicate exchange rate from USD to local currency (e.g. 1 USD = 79.9 Brazilian Real): 1 USD =:

-2.17

Indicate average wage cost of hired labour per day:

8.80

4.3 Establishment activities

Activity Timing (season)
1. Field survey and location selection Before design
2. Design before construction
3. Build the dam wall
4. Check and accept After the construction

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 Building the wall/ field survey and planning Person/day 180.0 8.8 1584.0 90.0
Labour Building the wall/ field survey Machine/hrs 75.0 43.8 3285.0
Construction material Stone m^3 40.0 26.35 1054.0
Total costs for establishment of the Technology 5923.0
Total costs for establishment of the Technology in USD -2729.49
Comments:

Duration of establishment phase: 1 month(s)

4.5 Maintenance/ recurrent activities

Activity Timing/ frequency
1. check the dam wall annually

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 check annualy the dam wall Person/day 15.0 8.8 132.0
Total costs for maintenance of the Technology 132.0
Total costs for maintenance of the Technology in USD -60.83
Comments:

Machinery/ tools: crawler type bulldozer, giant jet, tractor, traditional tools, ruler,

The grass on both sides of check wall is natural grass.

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

The wide of dam wall affects the cost greatly, the wider, more expensive.The labour cost and the distance of rock quarry are also important.

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:

The mean annual rainfall in the basin is 515.2 mm in the duration from 1952 to 2000. The rainfall from May to Oct accounts for 446.8 mm, up to 86.7%; and that from Jun to Sep accounts for 367.6 mm, up

Agro-climatic zone
  • semi-arid

Thermal climate class: temperate. The accumulating time that temperature above 0 ℃ about 3800 hours, and that above 10 ℃ is more than 3200 hours
It is based on the classification sysytem only based on the rainfall.

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:

Altitudinal zone: All check dam and check dam liand here is in such altitudinal zonation.

Slopes on average: Based on 1:100 thousand scale landform map

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:
  • low (<1%)
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: The depth of Loess varies from nearly 30 m to more than 100 m in Yanhe River Basin. The depth of soil is less than this but it could be nearly 10 meters in commom.

Soil texture: There are more than 50% soil particle which are fine sand with size between 0.05 and 0.1 mm

Soil fertility very low: Lack of N, P and SOM

Topsoil organic matter: <0.5%

Soil drainage / infiltration good: The inflitration in Loess is very fast, but it prones to sealing when flashing

Soil water storage capacity low: Evaporation and drainage are easy

5.4 Water availability and quality

Ground water table:

5-50 m

Availability of surface water:

medium

Water quality (untreated):

poor drinking water (treatment required)

Comments and further specifications on water quality and quantity:

Availability of surface water also poor/ none and: Nearly all the branches of Yanhe are seasonal rivers

Availability of surface water medium: It is very stable in this region

Water quality (untreated): Good quality for there are few pollution sources

5.5 Biodiversity

Species diversity:
  • medium
Comments and further specifications on biodiversity:

It is very stable in this region

5.6 Characteristics of land users applying the Technology

Market orientation of production system:
  • mixed (subsistence/ commercial)
  • commercial/ market
Off-farm income:
  • 10-50% of all income
Relative level of wealth:
  • average
Individuals or groups:
  • groups/ community
Level of mechanization:
  • animal traction
  • mechanized/ motorized
Gender:
  • women
  • men
Indicate other relevant characteristics of the land users:

Land users applying the Technology are mainly Leaders / privileged

Difference in the involvement of women and men: No clear difference

Population density: 50-100 persons/km2

Annual population growth: < 0.5%

(The Check dam for land are build together in some villages for all the people funded by national sub).

Level of mechanization also manual work: The harvesting and other management are by hand

Level of mechanization animal traction: Tillage with animal power mostly

Level of mechanization mechanized/motorized: Tillage with machine in large area check-dam land.

Market orientation of production system mixed: Some production for themselves, but most of production is exchanged on the market.

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)?
  • small-scale
Comments:

According to 0.054 ha per capita

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

Land ownership:
  • state
  • communal/ village
Land use rights:
  • individual
Water use rights:
  • open access (unorganized)
Comments:

Like other rural areas in China

5.9 Access to services and infrastructure

health:
  • poor
  • moderate
  • good
education:
  • poor
  • moderate
  • good
employment (e.g. off-farm):
  • 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

crop production

decreased
increased
Quantity before SLM:

600

Quantity after SLM:

6000

risk of production failure

increased
decreased
Quantity before SLM:

4500kg/ha

Quantity after SLM:

2500kg/ha

Comments/ specify:

In extreme year with great rainfall, low yield of check dam land

product diversity

decreased
increased

production area

decreased
increased
Quantity before SLM:

950

Quantity after SLM:

59

Socio-cultural impacts

national institutions

weakened
strengthened

situation of socially and economically disadvantaged groups

worsened
improved
Quantity before SLM:

200 kg

Quantity after SLM:

350 kg

Livelihoods and human well-being

reduced
improved

Ecological impacts

Water cycle/ runoff

excess water drainage

reduced
improved

groundwater table/ aquifer

lowered
recharge
Quantity before SLM:

8 m

Quantity after SLM:

4-6m

Soil

soil moisture

decreased
increased
Quantity before SLM:

12-16%

Quantity after SLM:

16-22%

soil loss

increased
decreased
Quantity before SLM:

60t/ha/yr

Quantity after SLM:

5t/ha/yr

Other ecological impacts

long time period to form land

increased
decreased
Comments/ specify:

Sediment from slope decelerate the process of building arable land. In other words the economic function can not appear soon.

6.2 Off-site impacts the Technology has shown

reliable and stable stream flows in dry season

reduced
increased

downstream flooding

increased
reduced
Quantity before SLM:

2events/yr

Quantity after SLM:

nearly no

groundwater/ river pollution

increased
reduced

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 rainstorm well
local windstorm well
Climatological disasters
How does the Technology cope with it?
drought well
Hydrological disasters
How does the Technology cope with it?
general (river) flood well

Other climate-related consequences

Other climate-related consequences
How does the Technology cope with it?
reduced growing period not known
Comments:

The better condition of soil and water of check dam land improves the capacity of land tp cope with the changing climate.

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:

positive

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

positive

Long-term returns:

positive

Comments:

In the first stage, there is no economic output but the check dam is going to fill up with sediments. Afterwards the check dam forms land and with it benefit which would keep up a long time.

6.5 Adoption of the Technology

  • 11-50%
If available, quantify (no. of households and/ or area covered):

675 households in an area of 19.4 km^2 (11 percent of the area)

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

100% of land user families have adopted the Technology with external material support

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

Comments on acceptance with external material support: All the lands (cropland on the slope or check dam land and forest et al, ) are shared evenly by people. Of course, the work like to build check dam should be finished by all the families.

Comments on spontaneous adoption: No single farmer or family can finish this work because the land right and great investment.

There is a strong trend towards spontaneous adoption of the Technology

Comments on adoption trend: More and more local farmers want to get more check dam land for its long-term benefits.

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
The yield of check dam land is much higher than that on the slope land.

How can they be sustained / enhanced? Ask the local people to do more work without payment because they would get more benefits from this land as such.
The yield is stable because the soil moisture is good even in dry year

How can they be sustained / enhanced? Use the land efficient and mainten it.
Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
It could reduce the soil erosion originated from the gully.

How can they be sustained / enhanced? The local people know this benefit that make them try to find chance to build check dam.
The dam can retain the flow and sediment and reduces the sediment delivery of the downstream.

How can they be sustained / enhanced? Ask the people or government of the lower reaches to combat soil erosion through the building of check dams.
The check dam land is fertile and productive

How can they be sustained / enhanced? When we make the plan or design the construction, we should better take this into account.
Land is fertile and productive

How can they be sustained / enhanced? Improve the awareness of local people to use this technology.
The ceck dam can be used as rural road.

How can they be sustained / enhanced? When we make the plan or design the construction, we should better take this into account.

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?
It is too expensive to build the check dam. Ask the government or other organization and person to invest in check dams.The local people can work together without payment.
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view How can they be overcome?
The land in a check dam with less and less soil erosion on the slope, needs longer time to form It is difficult to overcome this because the control of erosion on slope has higher priority. We can find how to use the water or the temporary wetland.
The input of check dam is quite high. Ask the government or other organization and person to invest in check dams. The local people can work together without payment.

7. References and links

7.1 Methods/ sources of information

7.2 References to available publications

Title, author, year, ISBN:

Soil and water conservation records of Shaanxi Province. 2000. Shaanxi People's Press, Xi'an City, China

Available from where? Costs?

Library of ISWC, CAS

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