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

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

When were the data compiled (in the field)?

20/12/2008

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

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 imporved.

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

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.

3.1 Main purpose(s) of the Technology

• reduce, prevent, restore land degradation

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

Comments:

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

If land use has changed due to the implementation of the Technology, indicate land use before implementation of the Technology:

Mixed: Ms: Silvo-pastoralism

3.3 Further information about land use

Water supply for the land on which the Technology is applied:

• rainfed

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

3.4 SLM group to which the Technology belongs

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

3.5 Spread of the Technology

Comments:

Total area covered by the SLM Technology is 19.4 m2.

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.

3.6 SLM measures comprising the Technology

Comments:

Main measures: structural measures

3.7 Main types of land degradation addressed by the Technology

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

4.1 Technical drawing of the Technology

4.2 Technical specifications/ explanations of 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.

4.3 General information regarding the calculation of inputs and costs

Specify currency used for cost calculations:

• US Dollars

Indicate exchange rate from USD to local currency (if relevant): 1 USD =:

-2.17

4.4 Establishment activities

	Activity	Type of measure	Timing
1.	Field survey and location selection	Structural	Before design
2.	Design	Structural	before construction
3.	Build the dam wall	Structural
4.	Check and accept	Structural	After the construction

4.5 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

Comments:

Duration of establishment phase: 1 month(s)

4.6 Maintenance/ recurrent activities

	Activity	Type of measure	Timing/ frequency
1.	check the dam wall	Structural	annually

4.7 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

Comments:

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

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

4.8 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.

5.1 Climate

5.2 Topography

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

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

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

Comments and further specifications on biodiversity:

It is very stable in this region

5.6 Characteristics of land users applying the Technology

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 owned or leased by land users applying the Technology

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

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Socio-cultural impacts

Ecological impacts

Water cycle/ runoff

Soil

Other ecological impacts

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)

Gradual climate change

Gradual climate change

	Season	Type of climatic change/ extreme	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)?

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?

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

• 10-50%

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 have 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.

7.2 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