1.2 ព័ត៌មានលម្អិតពីបុគ្គលសំខាន់ៗ និងស្ថាប័នដែលចូលរួមក្នុងការវាយតម្លៃ និងចងក្រងឯកសារនៃបច្ចេកទេស

ឈ្មោះគម្រោងដែលបានចងក្រងឯកសារ/ វាយតម្លៃលើបច្ចេកទេស (បើទាក់ទង)

Water and Land Resource Centre Project (WLRC)

1.3 លក្ខខណ្ឌទាក់ទងទៅនឹងការប្រើប្រាស់ទិន្នន័យដែលបានចងក្រងតាមរយៈ វ៉ូខេត

តើពេលណាដែលទិន្នន័យបានចងក្រង (នៅទីវាល)?

12/05/2014

អ្នកចងក្រង និង(បុគ្គលសំខាន់ៗ)យល់ព្រមទទួលយកនូវលក្ខខណ្ឌនានាទាក់ទងទៅនឹងការប្រើប្រាស់ទិន្នន័យដែលបានចងក្រងតាមរយៈវ៉ូខេត:

បាទ/ចា៎

1.4 សេចក្តីប្រកាសស្តីពីចីរភាពនៃការពណ៌នាពីបច្ចេកទេស

តើបច្ចេកទេសដែលបានពណ៌នានេះមានបញ្ហាដែលផ្តោតលើការធ្លាក់ចុះគុណភាពដី, បើដូច្នេះវាមិនអាចត្រូវបានប្រកាសថាជាបច្ចេកទេសនៃការគ្រប់គ្រងប្រកបដោយចីរភាពទេ?

ទេ

1.5 ការយោងទៅលើកម្រងបញ្ជីសំណួរនៃវិធីសាស្ត្រផ្សព្វផ្សាយ SLM

2.1 ការពណ៌នាដោយសង្ខេបពីបច្ចេកទេស

និយមន័យបច្ចេកទេស:

Vegetated graded soil bund is a soil conservation practice meant for cultivated lands and constructed by excavating graded channel on upper side and develop embankment on lower side which is planted with grass or shrub species in order to control soil erosion and drain excess runoff implemented through community mobilization.

2.2 ការពណ៌នាលម្អិតពីបច្ចេកទេស

ការពណ៌នា:

Vegetated graded soil bund is a practice or soil conservation technology for cultivated lands and constructed by excavating graded channel and form embankment. It is practiced in areas where there is excess runoff to be disposed and where there is no stones available for construction. The design specifications (ditch gradient, width and height) and layout (spacing/vertical interval) vary on the amount of excess runoff and slope of the land. Soil bund construction begins from top of the catchment. Cut off drains are constructed on top of the catchment and where needed to drain excess runoff to well stabilized natural or man-made waterways. this helps to reduce runoff impact on gullies. The bund ditch/channel should be sufficient enough to drain excess runoff safely without causing channel erosion and creating downstream damages. At same time the embankment should be stable to withstand overflows and damage due to free grazing. One technique to stabilize bunds is to plant the embankment with grass and shrub species of multiple economic value in order to compensate production area lost by bund construction. Often, the species are preferably used for livestock feed. Thus, free grazing has to be controlled. To protect damage of channels and embankments by extreme runoff and floods, frequent supervision and maintenance is required.

The purposes are:
1) Reduce nutrient loss and soil erosion by shortening the slope length,
2) Safely drain excess runoff from upstream of gully into protected waterways,
4) Produce biomass of fodder and cash values.

Vegetated graded bunds are established by doing surveying using hand level to determine the layout of the technology along the slope. During the surveying, the position of bunds (spacing) and cutoff drains and connection to waterways are determined. Bunds are laid following 0.05% gradient and up to 80 m maximum length. The specifications of the structure are: height of bund is a minimum of 60 cm after compaction; depending on the soil, base width range between 1.0 and 1.5m; top width is between 30 and 50 cm. The construction is made across different parcels owned by different land users. If there is no natural waterways and where it is appropriate, paved waterways are constructed at every 80 m or less bund length to dispose drainage water. At the beginning of the rainy season, the embankments are covered with grass and/or shrubs either by direct sowing of seeds or planting the seedlings raised in the nurseries. Monitoring of damages due to flooding and animals, maintenance of the structure as well as replanting of dead seedlings on bunds is required to sustain the soil conservation technology.

The technology is appropriately applied in high rainfall and sub-humid areas of the sub-tropics, particularly where the soil is moderately deep and poorly drained. It is constructed on cultivated lands having slopes in the range of 3-15%. The practice can be constructed by land users. It also requires collective decision and actions to drain excess runoff through waterways. The living condition depends on subsistence crop-livestock mixed farming. On average households have 5-6 family size. Crop production is meant for home consumption with small surplus for local market. The services related to water supply, energy supply, and infrastructure are low. Besides it is an asset, animals often used to cope shocks during drought periods.

2.3 ​រូបភាពនៃបច្ចេកទេស

2.5 ប្រទេស/តំបន់/ទីតាំងកន្លែង ដែលបច្ចេកទេសត្រូវបានអនុវត្ត និងបានគ្រប់ដណ្តប់ដោយការវាយតម្លៃនេះ

2.6 កាលបរិច្ឆេទនៃការអនុវត្ត

ប្រសិនបើមិនច្បាស់ឆ្នាំ សូមបញ្ជាក់កាលបរិច្ឆេទដែលប្រហាក់ប្រហែល:

• តិចជាង 10ឆ្នាំមុន (ថ្មី)

2.7 ការណែនាំពីបច្ចេកទេស

សូមបញ្ជាក់តើបច្ចេកទេសត្រូវបានណែនាំឱ្យអនុវត្តដោយរបៀបណា:

• តាមរយៈគម្រោង / អន្តរាគមន៍ពីខាងក្រៅ

មតិយោបល់ (ប្រភេទនៃគម្រោង ។ល។):

The soil bunds are introduced before 30-40 years, however the integration of structural and combination of vegetative measures are applied in three years period in the WLRC learning watersheds.

3.1 គោលបំណងចម្បង (១​ ឬច្រើន)​ នៃបច្ចេកទេសនេះ

• កាត់បន្ថយ, បង្ការ, ស្តារឡើងវិញនូវការធ្លាក់ចុះគុណភាពដី

3.2 ប្រភេទដីប្រើប្រាស់មួយប្រភេទ (ច្រើនប្រភេទ) ដែលបានអនុវត្តបច្ចេកទេស

មតិយោបល់:

Major land use problems (compiler’s opinion): Land degradation due to sheet erosion, rills and gullies, soil nutrient depletion, overgrazing, shortage of fuel wood, excessive removal of crop residuals, loss of vegetation and deforestation
Major land use problems (land users’ perception): Soil erosion, soil nutrient depletion, shortage of pasture

3.3 ព័ត៌មានបន្ថែមអំពីអ្នកប្រើប្រាស់ដី

ការផ្គត់ផ្គង់ទឹកនៅកន្លែងអនុវត្តបច្ចេកទេស:

• ប្រព័ន្ធស្រោចស្រពទាំងស្រុង

ចំនួនសារដែលដាំដំណាំក្នុងមួយឆ្នាំ:

• 1

សូមបញ្ជាក់:

Longest growing period in days: 210, Longest growing period from month to month: June-December; Second longest growing period in days: 180, Second longest growing period from month to month: June-November

3.4 ក្រុម SLM ដែលបច្ចេកទេសស្ថិតនៅក្នុង

• វិធានការអនុវត្តកាត់ទទឹងទីជម្រាល

3.5 ការសាយភាយនៃបច្ចេកទេស

មតិយោបល់:

Total area covered by the SLM Technology is 20 m2.
The technology is applied on specific conditions within the watersheds or area of adoption

3.6 វិធានការ SLM ដែលបញ្ចូលនូវបច្ចេកទេស

មតិយោបល់:

Type of vegetative measures: aligned: -graded strips

3.7 កំណត់ប្រភេទនៃការធ្លាក់ចុះគុណភាពដីសំខាន់ៗដែលបច្ចេកទេសនេះបានដោះស្រាយ

មតិយោបល់:

Main causes of degradation: soil management (High tillage frequency on annual basis and steep slope cultivation), crop management (annual, perennial, tree/shrub) (The cropping system is cereal based that induce erosion), overgrazing (Livestock graze on crop residues after harvesting of crops), Heavy / extreme rainfall (intensity/amounts) (Extreme rainfall cause for high erosion), other natural causes (avalanches, volcanic eruptions, mud flows, highly susceptible natural resources, extreme topography, etc.) specify (Steep slopes or rugged topography), population pressure (Result in expansion of crop lands to steeper slopes)
Secondary causes of degradation: deforestation / removal of natural vegetation (incl. forest fires) (Deforestation of scattered trees in the farm and forests upstream of crop lands), land tenure (Insecure tenure play role not to invest on long term), poverty / wealth (Poor can not afford to invest on soil conservation on his parcel), education, access to knowledge and support services, governance / institutional

3.8 ការពារ កាត់បន្ថយ ឬស្តារឡើងវិញនៃការធ្លាក់ចុះគុណភាពដី

បញ្ជាក់ពីគោលដៅរបស់បច្ចេកទេស ដែលផ្តោតទៅការធ្លាក់ចុះគុណភាពដី:

• ការកាត់បន្ថយការធ្លាក់ចុះគុណភាពដី

4.1 គំនូសបច្ចេកទេសនៃបច្ចេកទេសនេះ

4.2 លក្ខណៈពិសេសនៃបច្ចេកទេស/ ពណ៌នាពីគំនូរបច្ចេកទេស

Vegetated graded soil bund showing the excavated ditch or channel and the embankment planted with grass and shrubs
Location: Amhara Region. Mecha, Yilmana Densa, Bahir Dar Zuria and Dessie Z

Technical knowledge required for field staff / advisors: high (Layout and design specification of soil bunds and cutoff drains vary on soil types, slopes, and rainfall conditions. Experts thus should acquire knowledge on specific hydrologic conditions)
Technical knowledge required for land users: moderate (Land users need skill to layout and construct bunds, monitor structures before the occurrence of excessive damage, and do regular maintenance)

Main technical functions: control of dispersed runoff: impede / retard, reduction of slope length, sediment retention / trapping, sediment harvesting, increase of biomass (quantity)
Secondary technical functions: control of dispersed runoff: retain / trap, reduction of slope angle, increase / maintain water stored in soil, increase of groundwater level / recharge of groundwater

Aligned: -graded strips
Vegetative material: T : trees / shrubs, C : perennial crops, G : grass
Number of plants per (ha): T=5333, C=160, G=1600
Vertical interval between rows / strips / blocks (m): 1-1.5
Spacing between rows / strips / blocks (m): 10-20
Vertical interval within rows / strips / blocks (m): T=0.3, C=5, G=0.5
Width within rows / strips / blocks (m): 0.3
Trees/ shrubs species: Cordia Africana, Polycantha, Sesbania Susban, Pigeon pea, Treelucer
Perennial crops species: Rhamnus
Grass species: Napier grass
Slope (which determines the spacing indicated above): 3-15%
Gradient along the rows / strips: 0.05%
Diversion ditch/ drainage
Depth of ditches/pits/dams (m): 0.3-0.7
Width of ditches/pits/dams (m): 1.2-2.8
Length of ditches/pits/dams (m): 100-250

Waterway
Depth of ditches/pits/dams (m): 0.3
Width of ditches/pits/dams (m): 1.5-2.0

Bund/ bank: graded
Vertical interval between structures (m): 1-1.5
Spacing between structures (m): 10-20
Depth of ditches/pits/dams (m): 0.5
Width of ditches/pits/dams (m): 0.3
Height of bunds/banks/others (m): 0.6
Width of bunds/banks/others (m): 1-1.5
Length of bunds/banks/others (m): 50-80

Construction material (earth): in-situ excavated soil
Slope (which determines the spacing indicated above): 3-15%
Lateral gradient along the structure: 0.05%
Vegetation is used for stabilisation of structures.

4.3 ព័ត៌មានទូទៅដែលពាក់ព័ន្ធនឹងការគណនាធាតុចូល និងថ្លៃដើម

ផ្សេងៗ/ រូបិយប័ណ្ណជាតិ (បញ្ជាក់):

ETH BIRR

កំណត់អត្រាប្តូរប្រាក់ពីដុល្លាទៅរូបិយប័ណ្ណតំបន់ (បើទាក់ទង)៖ 1 ដុល្លារ =:

20,0

4.4 សកម្មភាពបង្កើត

	សកម្មភាព	ប្រភេទវិធានការ	ពេលវេលា
1.	Preparing planting materials	សារពើរុក្ខជាតិ	January-May
2.	Preparation of planting materials	សារពើរុក្ខជាតិ	January-May
3.	Transportation of grass splits/cuttings	សារពើរុក្ខជាតិ	Start of rainy season/July
4.	Transporting tree seedlings	សារពើរុក្ខជាតិ	Start of rain season/July
5.	Planting grass splits/cuttings	សារពើរុក្ខជាតិ	Start of rainy season/July
6.	Sowing seeds on bunds	សារពើរុក្ខជាតិ	Start of rainy season/July
7.	Planting tree seedlings on bunds	សារពើរុក្ខជាតិ	Starting of rainy season/July
8.	Surveying (layout of structures)	រចនាសម្ព័ន្ធ	After crop harvest and before first tillage operation
9.	Construction of cutoff drains	រចនាសម្ព័ន្ធ	January-April
10.	Construction of bunds (ditch and embankment)	រចនាសម្ព័ន្ធ	January-April
11.	Construction of waterways	រចនាសម្ព័ន្ធ	January - April

4.5 ថ្លៃដើម និងធាតុចូលដែលត្រូវការសម្រាប់ការបង្កើតបច្ចេកទេស

	បញ្ជាក់ពីធាតុចូល	ឯកតា	បរិមាណ	ថ្លៃដើមក្នុងមួយឯកតា	ថ្លៃធាតុចូលសរុប	% នៃថ្លៃដើមដែលចំណាយដោយអ្នកប្រើប្រាស់ដី
កម្លាំងពលកម្ម	labour	ha	1,0	1107,0	1107,0	79,0
សម្ភារៈ	animal traction	ha	1,0	4,0	4,0	100,0
សម្ភារៈ	tools	ha	1,0	300,6	300,6	50,0
សម្ភារៈដាំដុះ	seedlings	ha	1,0	32,0	32,0	100,0
សម្ភារៈដាំដុះ	seeds	ha	1,0	9,0	9,0	100,0
សម្ភារៈដាំដុះ	compost manure	ha	1,0	2,0	2,0	100,0
សម្ភារៈសាងសង់	stone	ha	1,0	1300,0	1300,0	100,0
សម្ភារៈសាងសង់	wood	ha	1,0	110,0	110,0	100,0
សម្ភារៈសាងសង់	earth	ha	1,0	25,2	25,2	100,0
ថ្លៃដើមសរុបក្នុងការបង្កើតបច្ចេកទេស					2889,8

មតិយោបល់:

Duration of establishment phase: 15 month(s)

4.6 សកម្មភាពថែទាំ

	សកម្មភាព	ប្រភេទវិធានការ	ពេលវេលា/ ភាពញឹកញាប់
1.	Preparation of planting materials	សារពើរុក្ខជាតិ	January - May
2.	Transportation of seedlings	សារពើរុក្ខជាតិ	July
3.	Re-plantation of seedlings and grass splits	សារពើរុក្ខជាតិ	July
4.	Maintenance of bunds, cutoff drain and waterways	រចនាសម្ព័ន្ធ	January-April

4.7 កំណត់ថ្លៃដើមសម្រាប់ការថែទាំ/ សកម្មភាពរបស់បច្ចេកទេស (ក្នុងរយៈពេលមួយឆ្នាំ)

	បញ្ជាក់ពីធាតុចូល	ឯកតា	បរិមាណ	ថ្លៃដើមក្នុងមួយឯកតា	ថ្លៃធាតុចូលសរុប	% នៃថ្លៃដើមដែលចំណាយដោយអ្នកប្រើប្រាស់ដី
កម្លាំងពលកម្ម	labour	ha	1,0	279,0	279,0	100,0
សម្ភារៈដាំដុះ	seedlings	ha	1,0	20,0	20,0	100,0
ថ្លៃដើមសរុបសម្រាប់ការថែទាំដំណាំតាមបច្ចេកទេស					299,0

មតិយោបល់:

Machinery/ tools: Cart, plastic tubes, spade, pickaxe, hand level, graduated ranging pole, spade, pickaxe, crowbar, hammer
The costs are calculated based on the labour, seedling/seed, grass splits required per hectare

4.8 កត្តាសំខាន់បំផុតដែលមានឥទ្ធិពលដល់ការចំណាយ

ពណ៌នាពីកត្តាប៉ះពាល់ចម្បងៗទៅលើថ្លៃដើម:

The cost variation in implementing vegetated soil bund is dependent upon availability of stones, workability of the soil, cost of seeds or seedlings for plantation, and distance for transporting seedlings.

5.1 អាកាសធាតុ

5.2 សណ្ឋានដី

5.3 ដី

5.4 ទឹកដែលអាចទាញមកប្រើប្រាស់បាន និងគុណភាពទឹក

5.5 ជីវៈចម្រុះ

5.6 លក្ខណៈនៃអ្នកប្រើប្រាស់ដីដែលអនុវត្តបច្ចេកទេស

សូមបញ្ជាក់ពីលក្ខណៈពាក់ព័ន្ធផ្សេងទៀតអំពីអ្នកប្រើប្រាស់ដី:

Land users applying the Technology are mainly common / average land users
Difference in the involvement of women and men: Women are involved in the construction of bunds with role of collecting stones, stabilize/compact the embankments and sometimes help men in excavating the earth
Population density: 200-500 persons/km2
Annual population growth: 2% - 3%
80% of the land users are average wealthy.
20% of the land users are poor.
Off-farm income specification: Land users often do not have access to off-farm income unless those who are young and own small size of land go for seasonal labor to towns during the slack period

5.7 ទំហំផ្ទៃដីជាមធ្យមនៃដីផ្ទាល់ខ្លួន ឬជួលគេដែលបានអនុវត្ត​បច្ចេកទេស

5.8 ភាពជាម្ចាស់ដី កម្មសិទ្ធប្រើប្រាស់ដី និងកម្មសិទ្ធប្រើប្រាស់ទឹក

ភាពជាម្ចាស់ដី:

• រដ្ឋ

កម្មសិទ្ធិប្រើប្រាស់ដី:

• ឯកជន

កម្មសិទ្ធប្រើប្រាស់ទឹក:

• អាស្រ័យផលសេរី (មិនមានការកំណត់)
• ជាក្រុម (មានដែនកំណត់)

5.9 ការប្រើប្រាស់សេវាកម្ម និងហេដ្ឋារចនាសម្ព័ន្ធ

6.1 ផលប៉ះពាល់ក្នុងបរិវេណអនុវត្តបច្ចេកទេសដែលកើតមាន

ផលប៉ះពាល់លើសេដ្ឋកិច្ចសង្គម

ផលិតផល

ចំណូល និងថ្លៃដើម

ផលប៉ះពាល់ទៅលើវប្បធម៌សង្គម

ផលប៉ះពាល់ទៅលើអេកូឡូស៊ី

វដ្តទឹក/លំហូរ

ដី

6.2 ផលប៉ះពាល់ក្រៅបរិវេណអនុវត្តបច្ចេកទេសដែលកើតមាន

6.3 ភាពប្រឈម និងភាពរួសនៃបច្ចេកទេសទៅនឹងការប្រែប្រួលអាកាសធាតុ និងគ្រោះអាកាសធាតុ/ គ្រោះមហន្តរាយ (ដែលដឹងដោយអ្នកប្រើប្រាស់ដី)

គ្រោះអាកាសធាតុ (មហន្តរាយ) ​

គ្រោះមហន្តរាយធម្មជាតិ

	លក្ខណៈឆ្លើយតបនៃបច្ចេកទេសទៅនឹងការប្រែប្រួលអាកាសធាតុ
ព្យុះភ្លៀងតាមតំបន់	ល្អ

គ្រោះមហន្តរាយទឹក

	លក្ខណៈឆ្លើយតបនៃបច្ចេកទេសទៅនឹងការប្រែប្រួលអាកាសធាតុ
ទឹកជំនន់ទូទៅ (ទន្លេ)	មិនល្អ

មតិយោបល់:

The technology has sufficient drainage ditch to tolerate excess runoff occurred during heavy rainfall events. However, it is sensitive to floods unless flood management measures such as strong cutoff drains and waterways are implemented

6.4 ការវិភាគថ្លៃដើម និងអត្ថប្រយោជន៍

តើផលចំណេញ និងថ្លៃដើមត្រូវបានប្រៀបធៀបគ្នាយ៉ាងដូចម្តេច (ទស្សនៈរបស់អ្នកប្រើប្រាស់ដី)?

តើផលចំណេញ និងការថែទាំ/ ជួសជុលត្រូវបានប្រៀបធៀបគ្នាយ៉ាងដូចម្តេច (ទស្សនៈរបស់អ្នកប្រើប្រាស់ដី)?

មតិយោបល់:

The short term economic benefits of the technology includes increase in fodder production and slightly crop productivity due to improved soil moisture. Whereas the long term benefit can be obtained as a result of increased yield on areas where sediment accumulation occurs as well as production of fodder on soil bunds for livestock feed

6.5 ការទទួលយកបច្ចេកទេស

មតិយោបល់:

The technology is implemented using community mobilization approach which involves all land users. All land users, who cultivate land in areas where bunds are suitable, implemented the technology. All parcels are covered with the technology/bunds except homesteads and degraded hillsides and gullies which are treated with different SLM technologies
Since the approach encourages collective action (through community organizations) to integrate different SLM technologies in the watershed level, there is no attempt by individual land users. However, there are motivations and implementation of land users on adjacent watersheds to implement the technology.
There is a moderate trend towards spontaneous adoption of the Technology
The trend is at increasing rate although land users need material support such as multipurpose seedlings to stabilize bunds. There is shortage of supply of fodder seeds. Community nurseries are inadequate and not well supported to raise seedlings to meet community demands.

6.7 ភាពខ្លាំង/ គុណសម្បត្តិ/ ឱកាសនៃបច្ចេកទេស

ភាពខ្លាំង/ គុណសម្បត្តិ/ ឱកាសនៅកន្លែងរបស់អ្នកប្រើប្រាស់ដី
Increase in fodder production for livestock feed
Reduce conflict among adjacent land users (i.e., upstream and downstream land users) that arise due to concentrated runoff
Reduce soil erosion

ភាពខ្លាំង/ គុណសម្បត្តិ/ ឱកាស​ ទស្សនៈរបស់បុគ្គលសំខាន់ៗ
The technology reduces soil loss and associated nutrient loss significantly in the first 3 to 4 years and further reduce siltation of reservoirs and land degradation
Increase the soil moisture in the landscape/watershed
Improves the greenness, soil carbon and micro-climate
Increase level of awareness of land users to produce fodder and diversify production and income
Reduce the concentration of runoff and safely drain without causing damage

6.8 ភាពខ្សោយ/ គុណវិបត្តិ/ ហានិភ័យនៃបច្ចេកទេស និងវិធីសាស្ត្រដោះស្រាយ

ភាពខ្សោយ/ គុណវិបត្តិ/ ហានិភ័យ ទស្សនៈរបស់អ្នកប្រើប្រាស់ដី	តើបច្ចេកទេសទាំងនោះបានដោះស្រាយបញ្ហាដូចម្តេច?
Hinder farm operations like turning oxen become difficult while ploughing	It can be sustained through proper layout and allow space for human and animal paths
Plantation on bunds harbor birds	This can be avoided by harvesting the mature branches of the shrubs for livestock feed on seasonal basis.
Appearance of new weeds species along the drainage ditches	Regular weed monitoring and manual control
Hinders livestock to graze on crop residues	Try to use cut and carry grazing system (both crop residues and fodders) and develop forage development strategies in every possible niches

ភាពខ្សោយ/ គុណវិបត្តិ/ ហានិភ័យ ទស្សនៈរបស់អ្នកចងក្រងឬបុគ្គលសំខាន់ៗ	តើបច្ចេកទេសទាំងនោះបានដោះស្រាយបញ្ហាដូចម្តេច?
High labor requirement to establish and maintain the technology	Increase the awareness level of land users and strength collective actions and local organizational setups
Small land loss for construction	Introduce production options (like fodder production) on bunds to compensate the lost land
It requires some years to accumulate sediment on bund area and form bench	It can be improved by modifying the design of drainage ditchs

7.1 វិធីសាស្ត្រ/ ប្រភពនៃព័ត៌មាន

7.2 ឯកសារយោងដែលបានចេញផ្សាយ

ចំណងជើង អ្នកនិពន្ធ ឆ្នាំ ISBN:

Vegetated Graded Soil Bund: A Technique to Reduce Runoff Impact and Increase Soil Moisture Storage and Fodder Biomass, WLRC Brief No. 4

មានប្រភពមកពីណា? ថ្លៃដើមប៉ុន្មាន?

WWW.wlrc-eth.org