BASIN PROFILE OF THE LOWER SEKONG, SESAN AND SREPOK … · Basin Profile of the Lower Sekong, Sesan and Srepok (3s) Rivers in Cambodia 6 with limited agricultural development in the

BASIN PROFILE OF THE LOWER SEKONG, SESAN AND SREPOK (3S) RIVERS IN CAMBODIA

August 2013 Paradis Someth, Sochiva Chanthy, Chhorda Pen, Piseth Sean, Leakhena Hang

MK3 Optimising cascades

of hydropower

BASIN PROFILE

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Authors Paradis Someth, Sochiva Chanthy, Chhorda Pen, Piseth Sean, Leakhena Hang

Produced by Mekong Challenge Program for Water & Food Project 3 – Optimising cascades of hydropower for multiple use Led by ICEM – International Centre for Environmental Management

Suggested citation Someth, P. et al. 2013. Basin Profile of the Lower Sekong, Sesan and Spreok (3S) Rivers in Cambodia. Project report: Challenge Program on Water & Food Mekong project MK3 “Optimizing the management of a cascade of reservoirs at the catchment level”. ICEM – International Centre for Environmental Management, Hanoi Vietnam, 2013

More information www.optimisingcascades.org | www.icem.com.au

Image Cover image: High flows in Sesan river at Ta Veaeng (Photo Peter-John Meynell). Inside page: Sesan river near the border between Cambodia and Vietnam, a few kilometres below the proposed dam site of Sesan1/5 HPP (Photo Peter-John Meynell).

Project Team Peter-John Meynell (Team Leader), Jeremy Carew-Reid, Peter Ward, Tarek Ketelsen, Matti Kummu, Timo Räsänen, Marko Keskinen, Eric Baran, Olivier Joffre, Simon Tilleard, Vikas Godara, Luke Taylor, Truong Hong, Tranh Thi Minh Hue, Paradis Someth, Chantha Sochiva, Khamfeuane Sioudom, Mai Ky Vinh, Tran Thanh Cong

Copyright 2013 ICEM - International Centre for Environmental Management

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http://www.optimisingcascades.org/

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MEKONG CPWF| Optimising cascades of hydropower (MK3) Basin Profile of the Lower Sekong, Sesan and Srepok (3s) Rivers in Cambodia

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TA BLE OF CON TEN TS 1 FOREWORD ................................................................................................................................. 5

2 TOPOGRAPHY ............................................................................................................................. 5

3 HYDROMETEOROLOGY ............................................................................................................... 7

4 WATER QUALITY ....................................................................................................................... 16 4.1 Water quality data ...................................................................................................................... 16 4.2 Water level fluctuation and water pollution in the Sesan River in Cambodia ........................... 17

5 SOIL TYPES ................................................................................................................................ 18

6 LAND COVER AND LAND USE .................................................................................................... 21 6.1 Forest coverage .......................................................................................................................... 22 6.2 Agricultural land ......................................................................................................................... 23 6.3 Land use related to agricultural activities for family use ........................................................... 24 6.4 Aquatic ecosystems .................................................................................................................... 24

7 BIODIVERSITY AND NATIONAL RESOURCES............................................................................... 27 7.1 Protected areas .......................................................................................................................... 27 7.2 Non-timber forest products (NTFP) ............................................................................................ 27 7.3 Mining......................................................................................................................................... 29 7.4 Fisheries ...................................................................................................................................... 30

8 INFRASTRUCTURE ..................................................................................................................... 31 8.1 Domestic water supply ............................................................................................................... 31 8.2 Transport .................................................................................................................................... 31 8.3 Energy ......................................................................................................................................... 32

9 SOCIO-ECONOMIC PROFILE ....................................................................................................... 32 9.1 Populations ................................................................................................................................. 32 9.2 Access to public services ............................................................................................................ 34 9.2.1 Access to safe water ............................................................................................................... 34 9.2.2 Access to sanitation ............................................................................................................... 34 9.2.3 Access to health care.............................................................................................................. 34 9.2.4 Illiteracy .................................................................................................................................. 34 9.2.5 Access to land resources ........................................................................................................ 34

10 DEVELOPMENT TRENDS IN THE 3S CATCHMENT ................................................................... 36 10.1 Irrigation development............................................................................................................... 36 10.2 Hydropower development ......................................................................................................... 37 10.3 A controversial project: Lower Sesan 2 ...................................................................................... 38

11 AGENCIES WITH FUNCTIONS AFFECTING WATER RESOURCES DEVELOPMENT ...................... 39

12 REFERENCES .......................................................................................................................... 45


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LIST OF FIGURES Figure 1. Provinces of the 3S Rivers catchment ..........................................................................................6 Figure 2. The location of meteorological and hydrological stations............................................................8 Figure 3. Long-term average maximum and minimum temperature and relative humidity at Stung Treng ................................................................................................................................................................... 10 Figure 4. Monthly rainfall at Siempang station as a representative for the Sekong catchment ............... 11 Figure 5. Monthly rainfall at Voeun Sai station as a representative for the Sesan catchment ................. 11 Figure 6. Monthly rainfall at Lumphat station as a representative for the Srepok catchment ................. 12 Figure 7. Monthly flow characteristics of the Sekong at Chantangoy ....................................................... 14 Figure 8. Monthly flow characteristics of the Sesan at Voeun Sai ............................................................ 14 Figure 9. Monthly flow characteristics of the Sesan at Andaung Meas .................................................... 15 Figure 10. Monthly flow characteristics of the Srepok at Lumphat .......................................................... 16 Figure 12. Changes in land cover in the 3S catchment .............................................................................. 23

LIST OF TABLES

Table 1. Summary of hydrometeorological data availability in the 3S catchment. ..................................... 9 Table 2. Long-term average climate components at Stung Treng (CNMC, 2009). ...................................... 9 Table 5. Monthly rainfall (mm) at Voeun Sai station as a representative for the Sesan catchment (CNMC, 2009). ........................................................................................................................................................ 11 Table 6. Monthly rainfall (mm) at Lumphat station as a representative for the Srepok catchment (Source: CNMC, 2009). .............................................................................................................................. 12 Table 7. Monthly flow (MCM) characteristics of the Sekong at Chantangoy (Source: CNMC, 2009). ...... 13 Table 8. Monthly flow (MCM) characteristics of the Sesan at Voeun Sai (Source: CNMC, 2009). ............ 14 Table 9. Monthly flow (MCM) characteristics of the Sesan at Andaung Meas (Source: CNMC, 2009). .... 15 Table 10. Monthly flow (MCM) characteristics of the Srepok at Lumphat (Source: CNMC, 2009). .......... 15 Table 11. Water quality indices of primary stations on the Sekong, Sesan and Srepok for 2004-2008 (Source: CNMC, 2009) ............................................................................................................................... 16 Table 12. Significant water quality parameters for the station on the Sekong, Sesan and Srepok (Source: MOWRAM, 2004-2008) ............................................................................................................................. 17 Table 13. Major soil types of 3S basins and their characteristics (Source: CNMC, 2009). ........................ 19 Table 14. Land use and land cover in the 3S catchment (Source: JICA, 2002). ......................................... 21 Table 15. Changes of land used for rice production (MAFF, 1980-2007). ................................................. 22 Table 16. Changes of land used for annual cash crop production (MAFF, 1980-2007). ........................... 22 Table 17. Changes in land cover in the 3S catchment (MRC, 1997; JICA, 2002). ...................................... 23 Table 18. List of food and crop plants in Sesan River homesteads (SWECO, 2006). ................................. 25 Table 19. List of forest products collected by villagers living in the Sesan catchment (SWECO, 2006). .. 28 Table 20. Proportion of vegetation type (% length) along the north and south Sesan River banks (measured along the Sesan River bank in Cambodia to its confluence with the Srepok River) (Source: SWECO, 2006)............................................................................................................................................ 28 Table 21. List of animals hunted by villagers living in the Sesan catchment (Source: SWECO, 2006). ..... 29 Table 22. Fish catch and fish consumption in the 3S catchment (ADB, 2010a). ....................................... 30 Table 23. Generation capacity and distribution lines in Stung Treng and Rattanakiri in 2007 (Source: EDC, 2008). ................................................................................................................................................ 32 Table 24. Population and age group (Commune Database, NIS, 2008). ................................................... 33 Table 25. Composition of population groups within the 3S catchment (Commune Database, NIS, 2008). ................................................................................................................................................................... 33 Table 26. Demography of 3S Basins (Commune Database, NIS, 2008). .................................................... 34 Table 27. Irrigation schemes in the 3S catchment (NCDD of Mondulkiri, Ratanakiri, Stung Treng, 2009). ................................................................................................................................................................... 36 Table 28. Potential irrigation area in the 3S catchment (NCDD of Mondulkiri, Ratanakiri, Stung Treng, 2009). ........................................................................................................................................................ 36 Table 29. Current condition of rice production in the 3S catchment (NCDD of Mondulkiri, Ratanakiri, Stung Treng, 2009). ................................................................................................................................... 37 Table 30. Potential irrigation development in the Sesan Basin. ................................................................ 37 Table 31. Potential hydropower development in the Sesan Basin (CNMC, 2009) (1 of 3). ....................... 37


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Table 32. Potential hydropower development in the Sesan Basin (CNMC, 2009) (2 of 3). ....................... 38 Table 33. Potential hydropower development in the Sesan Basin (CNMC, 2009) (3 of 3). ....................... 38

1 F OREW ORD

The Sekong, Sesan and Srepok Rivers are important transboundary tributaries of the Mekong River, accounting for 19 percent of the flow of the Mekong River’s total annual discharge. The Sesan and Srepok flow from the central highlands of Viet Nam through Cambodia’s Ratanakiri, Mondulkiri and Stung Treng before converging into Sekong. The Sekong, on the other hand, begins in Viet Nam and then flows through Southern Lao PDR into Cambodia and, before reaching Cambodia’s Stung Treng, it merges with the Sesan and Srepok rivers and finally the Mekong River.

Together these three rivers sustain the livelihoods of more than a hundred communities in northeastern Cambodia, which rely on them for fishing, farming and maintaining their cultural traditions. Besides, the 3S Rivers are a source of immense biodiversity, rich in fisheries and critical for the migration of fish species traveling to and from central Cambodia’s Tonle Sap Lake and from upstream areas of the Mekong Basin in Lao PDR and Thailand. Aquatic biodiversity and resources are threatened by changes in flows and water quality in the rivers. All basins report decline in fish production from a combination of loss of habitat, fishing pressure and illegal fishing methods; in the future these trends will increase due to changes induced by hydropower dams. The pressures on water resources across the 3S Basins are intensifying. These pressures could, in the future, undermine the ability of the countries (Cambodia, Lao PDR and Viet Nam) to meet their long-term development objectives. There is a need to address and manage these existing pressures and to strengthen cross border collaboration. However, until now, there has been no significant development in the water sector in Cambodia.

The report is a summary of general aspects covering hydrometeorology data, agricultural and industrial activities and potential hydropower development on the catchment of the Sekong, Sesan and Srepok Rivers (thereafter referred to as the 3S Rivers) in Cambodia. Since the data and information on the Sekong is limited, the report mainly focuses on the Sesan and Srepok Rivers. In Cambodia, the catchment of the 3S Rivers is mainly within two provinces, namely Stung Treng and Rattanakiri. Therefore, the data and information from the two provinces are extensively used in this report. Data and information available from existing reports, published literature, maps, statistics, databases, ministries and non-governmental organisations (NGOs) were gathered, compiled and summarised in concise forms. For detailed information on each specific section, readers are recommended to consult the references provided in the respective sections. The purpose of this catchment profile is to provide an overview of the characteristics and data and information availability in the catchment, for further information and accuracy of the data, information, value and figures, readers are advised to consult the references provided.

2 TOP OG RAPHY

The catchment of the Sekong, Sesan and Srepok (3S) Rivers is located in the northeast of Cambodia and covers a total area1 of approximately 26,521 km2.

This catchment includes partial or entire parts of three provinces: Stung Treng (62%), Ratanakiri (100%) and Mondulkiri (49%). The catchments are characterised by rugged terrain with peaks of over 1,546 m, and valleys at about 0-36 m. The majority of these areas remain under forest and woodland,

1 The total area of 3S catchment in Cambodia varies from 25,951 km2 (cited in JICA, 2000) to 26,521 km2 (cited in CNMC, 2009).


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with limited agricultural development in the valleys and shifting cultivation on the slopes. The steep slope of the rivers makes navigation in some stretches possible only during certain months of the year (especially during the rainy season) (CNMC, 2009).

Figure 1. Provinces of the 3S Rivers catchment


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The topography and geology of the Sesan catchment in Cambodia (especially Ratanakiri) is generally diverse, encompassing rolling hills, mountains, plateaus, lowland watershed and crater lakes. This can be divided into four ecological zones (Danith, 2001):

- The central plateau with highest elevation of over 500 m, near the border of Viet Nam with red fertile basaltic soils;

- The hilly region, covering 300 m elevation, is an important watershed of tributaries of both the Sesan and Srepok Rivers. It supports shifting cultivation on the red and gray forest soils;

- North of the Sesan River, where a major tributary Prek Liang is located, is older and non-volcanic terrain, and rises to 1,000 m elevation at certain points along the division between the Sekong and Sesan catchments;

- The last one is the lowland plains region, with elevations from 60-100 m, which supports lowland rice cultivation.

3 H YD ROM ETEOROLOG Y

The climate of the 3S catchment is governed by the Southwest Monsoon, which brings rains in the period from May until September/October. During the Northeast Monsoon (when the winds blow from the Chinese mainland), the temperatures drop (hot and dry) and rainfall is low (less humid). The detailed meteorological data of the 3S catchment are available only at Stung Treng. The location of meteorological and hydrological stations is presented in Figure 2. A summary of availability of the hydrometeorological data is shown in Table 1.

Daily temperature varies between the maximum of 36°C, during the hottest months of March/April, to 19°C during the coldest month of January. The daily minimum and maximum varies by between 6°C and 12°C. Table 2 presents the long-term average climate condition, observed at Stung Treng stations, together with Reference Evapotranspiration (ETo), computed by applying the Penman-Monteith method. This evapotranspiration is particularly high in March and April.


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Figure 2. The locations of meteorological and hydrological stations


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Table 1. Summary of hydrometeorological data availability in the 3S catchment. No Rainfall

station Catchment 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

1 Siempang Sekong - - - - - - - - - - - - - - A A A A A - A A A

2 Sen Monorom Srepok - - - - - - A - - - - - - - - - - - - - - - -

3 O Raing Srepok 62 A A A A A - A - - - - - - - - - - - - - - - 4 Lumphat Srepok A A A A A A - A - - - - - - - - A A A - A A - 5 Banlung Sesan - - - - - - - - - - - - - - - - A A A - A A A 6 Sesan Sesan - - - - - - - - - - - - - - - - - A A - A A A 7 O Chum Sesan - - - - - - - - - - - - - - - - 92 A A - A A - 8 Voeun Sai Sesan A A A A A A A A A - - - - - - - 274 A A - - A -

9 Andaung Meas Sesan - - - - - - - - - - - - - - - - A A A - A A -

No Hydrological station River 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

1 Ban Khmoun Sekong - 12 - 1 A A A A A A - - - - - - - - - - - - - 2 Siempang Sekong - - - - - A 92 72 153 - - - - - - - - 70 A A A A A 3 Chantangoy Sekong 67 - - - - - - - - - A A A A A A A A A A A - A

4 Ban Kamphun Sesan 69 A A A A A A A A A A A A A A A A A A 61 62 3 A

5 Voeun Sai Sesan - - - - - A 275 150 182 31 - - - - - - 274 A A A A A -

6 Andaung Meas Sesan - - - - - - - - - - - - - - - - 112 A A A 153 A -

7 Lumphat Srepok - - - - - 83 92 59 91 A - - - - - - 127 A A A 153 120 -

“A” indicates the data is available for a given year. “-” indicates no data for a given year. Figures indicate the number days missing in a given year.

Table 2. Long-term average climate components at Stung Treng (CNMC, 2009). Parameter Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

Tmax (°C) 30.5 32.8 34.4 34.4 32.2 31.1 30.0 30.0 29.4 30.0 29.4 29.4 31.1 Tmin (°C) 19.0 20.9 23.5 24.9 24.3 23.8 23.6 23.6 23.7 23.0 21.6 19.2 22.6 Relative humidity (%) 66.4 61.7 60.3 64.9 78.5 82.8 85.2 86.7 87.7 83.4 78.4 74.4 75.9

Wind speed (km/day) 146.9 112.3 95.0 103.7 95.0 121.0 121.0 121.0 95.0 138.2 164.2 172.8 123.8 Sunshine hour (hour/day) 8.9 8.8 8.7 8.3 7.2 6.4 6.2 5.6 5.1 7.5 8.3 8.6 7.5 Radiation (MJ/m2 day) 19.6 21.1 22.3 22.3 20.4 19.0 18.8 18.0 16.9 19.6 19.2 18.6 19.7

Reference evapotranspiration (mm/day) 4.2 4.7 5.1 5.2 4.5 4.1 4.0 3.8 3.5 4.0 3.9 3.9 4.2


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Table 3. Summary of flow measurement for the 3S Rivers (CNMC, 2009). No Station Name River Measurement numbers Year of measurement 1 Chantangoy Sekong 56 1992, 1993, 1996, 1999, 2000 2 Ban Kamphun Sesan 43 1992, 1993, 1999, 2000 3 Voeun Sai Sesan 24 2000 4 Andaung Meas Sesan 21 2000 5 Lumphat Srepok 68 2000, 2005, 2006

There are ten rainfall stations in the 3S catchment and the data availability can be seen in Table 1. Annual rainfall distribution over the 3S catchment varies from 1,496 mm to 2,447 mm with an average of 1,948 mm.

Figure 1. Long-term average maximum and minimum temperature and relative humidity at Stung

Treng

Three rainfall stations, Siem Pang, Voeun Sai and Lumphat, were selected as representative stations for Sekong, Sesan and Srepok catchments, respectively. These rainfall stations are usually located in the middle of the catchment and have reasonable long reliable records. A summary of the monthly rainfall at the stations are presented in Table 4-Table 6. Annual rainfall for Siem Pang, Voeun Sai and Lumphat ranges between 1,167 mm and 2,494 mm (average of 1,872 mm), between 1,846 mm and 3,149 mm (average of 2,405 mm) and between 1,091 mm and 2,707 mm (average of 1,705 mm), respectively.

Table 4. Monthly rainfall (mm) at Siempang station as a representative for the Sekong catchment (CNMC, 2009).

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1998 0 0 0 0 283 84 17 180 258 165 72 108 1,167 1999 18 7 25 298 255 428 420 207 295 160 72 41 2,226

2000 0 0 0 187 159 433 296 337 249 86 56 0 1,803 2001 12 16 11 10 258 395 390 622 447 320 12 2 2,495 2002 0 2 2 107 241 193 315 366 457 59 75 62 1,879

2004 10 13 2 18 81 293 162 698 235 30 60 16 1,618 2005 0 0 10 58 204 166 299 562 401 111 0 0 1,811 2006 20 9 45 78 123 186 560 433 356 151 15 0 1,976


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Average 8 6 12 95 201 272 307 426 337 135 45 29 1,872

Figure 2. Monthly rainfall at Siempang station as a representative for the Sekong catchment

Table 3. Monthly rainfall (mm) at Voeun Sai station as a representative for the Sesan catchment (CNMC, 2009).

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1961 0 0 0 47 62 191 467 833 359 380 32 0 2,370 1962 0 0 9 60 239 399 465 433 425 55 17 0 2,101 1963 0 0 5 0 177 293 262 475 498 127 10 0 1,847 1964 0 0 0 18 321 301 215 512 435 233 71 0 2,106 1965 0 0 0 93 346 596 480 337 610 36 5 0 2,503 1966 0 2 50 10 344 204 600 414 305 115 22 0 2,066 1967 0 0 0 109 165 532 572 732 422 0 0 0 2,532 1968 0 0 0 118 158 239 304 735 468 36 0 0 2,058 2000 - - - - - - 479 737 326 - - - - 2001 0 0 56 54 381 464 400 817 401 52 34 25 2,683 2002 0 0 18 113 164 477 315 797 683 300 152 27 3,046 2005 0 0 0 43 224 254 884 758 796 147 13 30 3,149 Average 0 0 13 60 235 359 454 632 477 135 32 7 2,406

Figure 3. Monthly rainfall at Voeun Sai station as a representative for the Sesan catchment


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Table 4. Monthly rainfall (mm) at Lumphat station as a representative for the Srepok catchment (Source: CNMC, 2009).


1961 0 0 0 86 294 313 288 599 438 228 13 0 2,259 1962 0 0 2 37 306 64 377 223 278 113 12 0 1,412 1963 0 0 42 0 115 319 239 164 419 111 4 0 1,413 1964 0 0 11 27 280 145 73 174 188 190 151 0 1,239 1965 0 0 0 29 122 163 282 279 166 50 0 0 1,091 1967 0 0 0 332 139 234 372 470 348 159 116 0 2,170 2000 0 0 0 187 159 433 296 337 249 86 0 0 1,747 2001 0 0 73 37 528 509 264 704 329 211 54 0 2,708 2002 0 0 5 29 198 198 350 404 488 109 10 0 1,791 2004 0 0 26 0 172 219 214 411 178 51 0 0 1,271 2005 0 0 0 0 0 220 520 528 286 98 7 0 1,659 Average 0 0 14 69 210 256 298 390 306 128 33 0 1,705

Figure 4. Monthly rainfall at Lumphat station as a representative for the Srepok catchment

The Srepok catchment in Cambodia measures 13,171 km2, which is part of the whole 29,800 km2 catchment area. The Srepok River rises in Central Viet Nam, it flows for 250 km within Cambodia territory and joins the Sesan River 30 km upstream of the confluence of the Sesan and Sekong Rivers. Eleven tributaries drain directly into the Srepok river, namely Or Kaong, Or Patinh Thum, Prek Dokyong, Prek Drang, Prek Nam Lieou, Prek Rue, Or Phlay, Prek Rouei, Prek Tramet, Prek Chbar and Prek Dak (CNMC, 2009).

The Sesan catchment in Cambodia measures 7,960 km2, of the whole 17,300 km2 catchment area2. The Sesan River rises in the Truong Son Range of Central Viet Nam and flows for over 200 km before entering Cambodia. While in Cambodia, this river flows with the length of 278 km before discharging into the Sekong River at Stung Treng. Seven tributaries flow into the Sesan River. They are Prek

2 The total area of each catchment of the 3S Rivers in Cambodia varies from report to report, e.g., the Sesan catchment ranging from 17,300 km2 (7,960 km2 in Cambodia) cited in (CNMC, 2009) to 18,570 km2 (or 6,960 km2 in Cambodia) or even to 18,888km2 cited in SWECO, 2007. This situation is similar in the other two catchments, Sekong and Srepok.


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Chhnang, Or Kan Sieng, Prek Lalai, Prek Banpang, Or Ta Phlay, Prek Lamong and Prek Liang (MRC, 2009). At the border to Viet Nam the average flow is observed at about 380 m3/s (SWECO, 2007

The Sekong catchment in Cambodia covers an area of 5,390 km2, as a part of the whole area of 32,200 km2. The Sekong River rises in the Annamite Mountain range at the border between Lao PDR and Viet Nam, and drains into the eastern part of the Bolovens Plateau east of Pakse. The Sekong River travels for 344 km in Laos and some 155 km in Cambodia, before meeting the Sesan near Stung Treng provincial town and finally discharging into the Mekong River. The Sekong River has four tributaries in total, namely, Prek Smang, Prek Khampha, Prek Kheh and Prek Nakalaeng (MRC, 2009).

It is reported that runoff pattern closely follows the rainfall pattern but is slightly buffered by retardation of runoff by the tropical evergreen rainforests in the mountains, and recharge and runoff from substantial groundwater aquifers under extensive plateaus of basaltic volcanic rocks. Recurrent flooding takes place during short periods late in the wet season (September–November), and may be aggravated by intense rainfall and flash floods with tropical cyclones from the East Sea.

Records of data and information on rainfall, water level and flow for the 3S catchment were disrupted for the 1970s and 1980s. A summary of rainfall, water level and flow data availability is presented in Table 1 and Table 3, and observation network is shown in Figure 2. There are seven water level stations and five of which have discharge observation. It is believed that Ban Kamphoun on the Sesan River has a long data record. It is noted that no information on the common datum is available for these stations.

Flow information at the five hydrological stations, where the observed discharges are available, is derived from the rating curves at those stations. There is only one flow monitoring station for the Sekong River. It is Chantangoy station, which is located near the confluence where the Sesan flows into the Sekong. In addition, there are three flow monitoring stations for the Sesan River, at Ban Kamphuon, Veun Sai and Andaung Meas. Only flow at Veun Sai and Andaung Meas can be used since flow at Ban Kamphuon were measured only during the low flow period (CNMC, 2009). Furthermore, there is only one flow monitoring station for the Srepok River at Lumphat, located about 30 km upstream from the confluence with the Sesan River. Average of monthly flow at Chantagnoy for the Sekong River, at Veun Sai and Andaung Meas for the Sesan River and at Lumphat for the Srepok are presented in Table 7-Table 10.

Table 5. Monthly flow (MCM) characteristics of the Sekong at Chantangoy (Source: CNMC, 2009).


1994 715 454 343 371 613 2,263 9,597 11,133 14,750 3,921 1,236 977 46,373

1995 792 499 377 329 406 934 3,208 7,999 12,234 4,835 1,984 1,040 34,637

1996 756 524 389 405 1,254 1,646 6,126 9,970 12,082 5,934 2,612 1,347 43,045

1997 735 471 422 511 677 1,598 6,518 18,507 9,113 5,095 1,479 924 46,050

1998 600 408 298 113 230 705 2,059 2,451 3,528 3,502 3,648 3,026 20,568

1999 879 504 329 735 1,780 3,599 6,210 13,657 7,525 4,315 3,601 1,686 44,820

2000 935 623 539 588 1,533 3,755 15,585 13,190 20,695 6,459 2,243 1,418 67,563

2001 1,281 821 638 620 1,086 2,934 8,182 19,611 13,758 4,827 2,203 1,135 57,096

2002 745 491 424 448 574 2,076 8,015 18,131 17,009 4,406 1,900 1,155 55,374

2003 743 504 488 446 892 2,003 2,797 7,268 12,219 3,723 1,614 1,087 33,784

2004 690 474 442 434 569 2,349 4,070 13,510 12,126 2,511 1,146 870 39,191

Average 806 525 426 455 874 2,169 6,579 12,312 12,276 4,503 2,151 1,333 44,409


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Figure 5. Monthly flow characteristics of the Sekong at Chantangoy

Table 6. Monthly flow (MCM) characteristics of the Sesan at Voeun Sai (Source: CNMC, 2009).

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1967 - - - 258 378 1,589 3,089 - - - - - 1968 - - - 307 - - - - 4,167 - - - - 1969 523 343 331 299 324 408 3,636 5,294 6,014 3,186 1,560 - 2000 - - - - 1,033 2,312 6,366 - - - - - - 2001 798 531 591 533 845 1,789 5,072 6,776 5,317 3,384 1,844 1,153 28,633 2002 809 300 407 275 385 1,142 3,464 5,817 6,816 3,515 1,978 1,262 26,170 2003 559 284 463 287 686 1,451 1,898 3,968 5,298 3,966 1,950 1,245 22,055 2004 524 380 556 401 344 1,790 2,228 - 5,291 2,475 1,198 790 - 2005 882 746 506 223 294 402 2,384 7,877 5,503 3,362 2,126 - - Average 683 431 476 323 536 1,360 3,517 5,946 5,487 3,315 1,776 1,113 25,619

Figure 6. Monthly flow characteristics of the Sesan at Voeun Sai


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Table 7. Monthly flow (MCM) characteristics of the Sesan at Andaung Meas (Source: CNMC, 2009).

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 2000 - - - - 1,509 2,420 5,022 2,003 1,685 1,327 1,051 442 - 2001 60 155 509 599 691 1,180 3,334 5,790 4,251 2,610 1,488 969 21,636 2002 774 535 550 366 444 713 2,023 3,298 4,482 2,288 1,377 889 17,739 2003 509 348 495 424 603 946 869 2,236 3,236 2,927 1,552 1,021 15,166 2004 451 379 503 463 313 1,215 1,614 - - - - - - 2005 345 191 187 329 276 320 1,252 4,620 3,830 2,038 1,321 966 15,675 Average 428 322 449 436 639 1,132 2,352 3,589 3,497 2,238 1,358 857 17,554

Figure 7. Monthly flow characteristics of the Sesan at Andaung Meas

Table 8. Monthly flow (MCM) characteristics of the Srepok at Lumphat (Source: CNMC, 2009).

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1965 1,282 - - - 995 2,374 2,955 2,692 4,644 1,905 907 969 18,723 1966 606 219 213 251 676 912 3,222 4,830 5,063 - - - - 1967 - - 281 567 1,509 3,811 2,779 3,267 5,511 2,559 1,188 820 - 1968 - - - 264 497 1,140 857 2,702 2,080 2,412 1,055 526 - 1969 160 81 54 55 384 499 1,880 1,919 6,449 4,179 815 413 16,888 1970 287 222 173 - - - - - - - - - - 2000 - - - - - 3,265 4,470 3,706 6,675 8,570 2,199 1,985 - 2001 843 401 366 349 758 2,230 2,377 8,907 3,780 3,216 1,456 814 25,497 2002 484 300 241 262 341 967 1,142 6,858 7,007 2,042 1,470 562 21,676 2003 494 402 364 368 840 1,510 1,753 3,687 4,911 3,355 1,822 751 20,257 2004 479 365 209 11 213 2,317 1,422 - - - - - - 2005 64 - - - - 436 1,915 5,741 6,170 1,730 1,096 2,052 -

Average 522 284 238 266 690 1,769 2,252 4,431 5,229 3,330 1,334 988 20,608


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Figure 8. Monthly flow characteristics of the Srepok at Lumphat

4 W A TER Q UA LITY 4 . 1 W A T E R Q U A L I T Y D A T A

Water quality data for the 3S Rivers were recorded from four stations: Phum Pi, Angdoung Meas, Siem Pang and Lumphat, for the periods of 2004-2008 (CNMC, 2009). There were three main categories of water quality indices: (i) water quality index for aquatic life (WQIal), (ii) water quality index for human impact (WQIhi), and (iii) water quality index for agricultural use (WQIag). Following the MRC guidelines (MRC, 2008), the WQIal was assessed from six parameters: (i) DO, (ii) pH, (iii) NH3, (iv) Conductivity, (v) NO3-2 and (vi) Total P. Likewise, WQIhi was assessed from three parameters: DO, CODmn, and NH4 while that of WQIag was assessed against the values of conductivity in sampled water (CNMC, 2009).

The result of water quality assessment (Table 11) shows that water quality of the 3S Rivers is still good quality for aquatic life as the value of WQIal for all stations ranges between 9.5-9; but quality for humans has been impacted as the WQIhi value is between 8.5-7; however, for general agriculture, paddy rice and livestock, the water quality is in excellent state as the values of the three WQIag indices are within the range of no restrictions (8.0-10.0) (CNMC, 2009).

Data on significant water quality parameters are presented in Table 12. Overall, the water quality of the 3S catchment presents pH value above neutrality and is well oxygenised. The levels of plant nutrients (phosphorus and nitrogen) are very low for sustaining the life of most algae including toxic blue green algae, and not significant enough to cause problems of eutrophication. The content of Total P is moderate, not at a level that could create problems for fish or other aquatic organisms.

Table 9. Water quality indices of primary stations on the Sekong, Sesan and Srepok for 2004-2008 (Source: CNMC, 2009)

Station River WQIal WQIhi WQIag-general WQIag-paddy WQIag livestock Siempang Sekong B (9.3) C (8.1) A (10.0) A (10.0) A (10.0) Andaung Meas Sesan B (9.2) C (8.1) A (10.0) A (10.0) A (10.0) Phum Pi Sesan B (9.5) C (7.6) A (10.0) A (10.0) A (10.0) Lumphat Srepok B (9.2) C (7.8) A (10.0) A (10.0) A (10.0) WQIal: (A) high quality for 10.0-9.5, (B) good quality for 9.5-9.0, (C) moderate quality for 9.0-7.0, (D) poor quality for <7.0; WQIhi: (A) not impact for 10.0-9.5, (B) slightly impacted for 9.5-8.5, (C) impacted for 8.5-7.0, (D) severely impacted for <7.0; WQIag: (A) no restrictions for 10.0-8.0, (B) some restrictions for 8.0-


17

7.0, (C) severe restrictions for <7.0.

Table 10. Significant water quality parameters for the station on the Sekong, Sesan and Srepok (Source: MOWRAM, 2004-2008)

Significant water quality parameters Siempang Andaung Meas Lumphat Phum Pi

Temperature (°C) 28.5 27.5 28.5 27.8 pH (-) 7.1 6.9 7.1 7.2 TSS (mg/L) 46.123 37.641 42.402 33.808 Conductivity (mS/m) 5.357 4.000 6.005 4.611 Ca (meq/L) 0.220 0.131 0.214 0.180 Mg (meq/L) 0.161 0.098 0.158 0.100 Na (meq/L) 0.131 0.132 0.174 0.137 K (meq/L) 0.025 0.040 0.041 0.042 ALK (meq/L) 0.435 0.295 0.432 0.316 Cl (meq/L) 0.028 0.025 0.057 0.037 SO4 (meq/L) 0.080 0.080 0.100 0.109 NO3 (mg/L) 0.075 0.107 0.205 0.100 NH4N (mg/L) 0.038 0.039 0.040 0.039 Tot P (mg/L) 0.067 0.069 0.089 0.043 DO (mg/L) 7.353 7.740 7.664 7.641 COD (mg/L) 2.820 2.091 3.238 3.387

4 . 2 W A T E R L E V E L F L U C T U A T I O N A N D W A T E R P O L L U T I O N I N T H E S E S A N R I V E R I N C A M B O D I A

Recent significant and sudden water level fluctuations (within 24-hours) in the 3S Rivers in Cambodia, especially in the Sesan River, have not all been related to the climate, but possibly directly related to upstream infrastructure operations. This is a recent observation and had not occurred previously. The following are some selected causes and consequences of the fluctuations, and the detail can be found in (3S Basins website, 2010).

- Unpredictable flows have started to be observed as a result of upstream dam operations. Water release from the dam is generally linked to variable electricity production and may cause disruption to natural water flows over short periods . In addition, filling of the reservoirs at the beginning of the wet season creates a deficit downstream, which may impact agricultural activities and aquatic life.

- Deforestation and change of land use patterns increase the runoff flows and generate more severe flood, including sudden flash floods in the wet season. In addition, this also decreases the rainfall infiltration into the aquifers and generates lower base flows in the dry season.

- The water quality in the Sesan River is reported to have seriously deteriorated since the construction of the upstream dam. The water in the river has become more turbid and has a bad smell (SWECO, 2007; ADB, 2010a).

The water quality in the Sesan River seems to be impacted by water infrastructure development/operations, intensive agriculture and high population density in the upper catchment, rather than by local sources of pollution. In addition, pollution due to mining activities is also mentioned (ADB, 2006). The pollution sources reported are (3S Basins website, 2010):


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- Areas of high density of population in the upper part of the Sesan and Srepok catchment located in Viet Nam, where human activities are the most developed (intensive cash crop agriculture and industries).

- Some significant areas near mining activities, urban areas and industrial development. - Poor water quality discharged at times from reservoirs of hydropower dams and storage

reservoirs for irrigation. - The present situation of the Sesan River can be described as follows (SWECO, 2006): - The water is soft with low content of dissolved ions with conductivity 3-4 mS/cm. - The water has weakly alkaline reaction with typical pH of 7.0-7.5. - Most of the year the turbidity is moderate (5-15 FNU), but in the rainy season turbidity can be

very high (200 FNU corresponding to 250-300 mg SS per litre). This high particle content causes problems for the river ecology and for human use.

- The content of the plant nutrients phosphorus and nitrogen is low and is not high enough to produce eutrophication problems.

- The algal biomass is low and the species composition is normal. - No content of algal toxins were observed in the sampling in Nov/Dec 2005, but this was not

studied in the most intensive algal producing period (April-June). - The concentrations of heavy metals, including arsenic, are low and reflect unpolluted water in

this respect. - The water has been analysed for 55 pesticides with detection limit of 0.01 ppb, but no

compound is detected. The conclusion is that pesticides are not a problem in Sesan River. - The content of coliform bacteria is periodically high, particularly in the rainy season. Drinking

water should be boiled, or filtered, before consumption. - It is not likely that the water coming out of the Yali Reservoir will contain enough nutrients to

create any algal problems in Sesan River in the future. However, Vietnamese monitoring data from 2004 found very high phosphorus content in samples taken just downstream the outlet of the reservoir.

On other hand, the river banks, especially along the Sesan River, are usually eroded due to high fluctuation of water level and the impact from the construction and operation of the hydropower plants upstream. The reservoirs will decrease sediment load and cause erosion downstream. When the sediment-free water (or sediment-hungry water) is released into the river downstream of the dam, it eats away the river banks to replenish its sediment load. Extensive erosion of the river banks makes it difficult for people to build ports or landing facilities on the river banks. Combined with rapid fluctuation in water level, improvement of the facilities is even more challenging.

5 S OI L TYP ES

The 3S catchment has seven major soil groups: Acrisols, Cambisols, Ferrasols, Gleysols, Leptosols, Planosols, and Vertisols. Acrisols are found either stand-alone or mixed with other soil groups. Thus there are actually eight different soil types as shown in Figure 3 and Table 13.

A very large proportion (40.3%) of the 3S catchment is covered by mixed Acrisols (poor acidic soil) and Leptosols (20% fine earth and 80% rock), which are not suitable for farming. Acrisols and Acrisol-mixed with other soil groups (Leptosols, Planosols and Cambisols) cover 73.3% of the catchment. Gleysols, which can be used for rice production and aquatic/semi-aquatic plants (vegetables, taro, lotus, etc.), cover 8.5% of the total area, while Ferrasols, which can be good for rubber and wood or


19

fruit tree plantation, cover 10.6%. The remaining 7.7% is Vertisols, which are good soils for most crops especially annual cash crops (CNMC, 2009).

Table 11. Major soil types of 3S basins and their characteristics (Source: CNMC, 2009).

No. Major soil types Area (ha) Percent (%) Summary of key characteristics

1 Acrisols 347,391 13.4

Acrisols are acidic, lack plant nutrients and have aluminum toxicity and high sensitivity to erosion thus pose limitations to permanent cropping. This soil type is generally used for subsistence farming and partly under shifting cultivation. Because they are not productive, only undemanding and/or acid-tolerant crops such as cashew and pineapple can perform well on this soil type.

2 Acrisols & Leptosols mixed 1045,699 40.3

Leptosols are shallow soils with various kinds of rock as their parent materials and thus have less than 20% of fine earth. This soil type has limited potential for tree crop production or extensive grazing and is best kept under forest. The combination of Acrisols and Leptosols, therefore, is soil/rock mixed that must remain under forest. Land with these soil types should be reserved for national park.

3 Acrisols & Planosols mixed 329,425 12.7

Planosols, a product of clayey alluvial and colluvial deposits, can be found in seasonally waterlogged flat lands. Because flooding is common during the wet season and drought occurs during the dry season, this soil type can be at best used for rice production during the wet season. The combination of Acrisols and Planosols is somewhat unattractive for any crop production. At best, only acid-tolerant rice crop can grow on this soil type.

4 Acrisols & Cambisols mixed

50,466 1.9

Cambisols, a product of alluvial and colluvial deposits, generally lack fertiliser elements and their structure is easily destroyable, thus they are not suitable for farming. The combination of Acrisols and Cambisols is, therefore, poor acidic soil that should be kept under forest, or at best serve as grazing lands.

5 Ferrasols 273,970 10.6

Ferrasols have good physical properties but are often chemically poor. Their low natural fertility, virtual absence of minerals and very low cation retention, are serious limitations for production of some crops. If brought into intensive agriculture, constant liming and fertiliser application is needed. Ferrasols can be used for fruit tree and rubber plantations.

6 Gleysols 219,903 8.5

Gleysols are present in areas with shallow groundwater, thus have clear excess wetness. Waterlogging is the main limitation for their utilisation. Gleysols are mostly used for grazing or are covered with swamp forest. Gleysols in the tropics and sub-tropics are widely planted with rice.

7 Leptosols 129,371 5.0 As has been described above, Leptosols have limited potential for tree crop production and should be best kept under forest.


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8 Vertisols 198,883 7.7

Vertisols are productive soils if properly managed. However, their fine texture and poor internal drainage account for their poor workability in both wet and dry condition. Vertisols are good for most annual cash crops (e.g., beans, groundnuts, etc.)


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Figure 11. Soil types of 3S catchment

6 LA ND COVER A ND LA ND US E

The 3S catchment is dominated by forest/vegetation3 (92.5%) while the remaining areas are agricultural land (6.0%), ecosystem area (1.4%), barren land and urban area (less than 1%). Area covered by each category is presented in Table 14 and land cover in the 3S catchment is shown in Figure 4.

Table 12. Land use and land cover in the 3S catchment (Source: JICA, 2002).

Land cover (ha) Sekong Sesan Srepok 3S catchment Percent

Aquatic ecosystems 10,172 13,449 11,579 35,200 1.40

Open water 8,044 8,895 7,041 23,980 0.95

Lake or pond 57 400 447 904 0.04

Seasonal flooded forest 637 4 0 641 0.03

Seasonal flooded grassland 99 0 0 99 0.00

Seasonal flooded shrubland 135 32 14 181 0.01 Marsh or swamp 1,200 4,118 4,077 9,395 0.37 Forest/Vegetation 548,092 512,289 1,271,798 2,332,179 92.52

Evergreen forest 191,993 164,593 102,106 458,692 18.20

Semi-evergreen forest 120,835 107,495 189,746 418,076 16.59

Deciduous forest 132,331 64,530 694,873 891,734 35.38

Woodland and scattered trees 74,779 85,335 123,533 283,647 11.25

Other forest 9,628 3,034 97,628 110,290 4.38

Grassland 9,099 11,222 22,651 42,972 1.70 Shrubland 9,427 76,080 41,261 126,768 5.03

Cultivated land 18,369 85,212 47,977 151,557 6.01

Annual cash crops 178 4,213 3,923 8,314 0.33

Orchard 0 3,283 2,495 5,779 0.23

Rice field 9,388 12,360 21,977 43,725 1.73

Swidden agriculture 8,299 64,388 18,533 91,220 3.62 Village garden crops 504 967 1,049 2,520 0.10

Barren land 335 473 89 897 0.04

Rock areas 19 11 0 30 0.00

Sand terrain 316 398 52 766 0.03 Other barren land 0 64 37 101 0.00 Urban built up and others 0 793 129 922 0.04

Total 576,968 612,216 1,331,572 2,520,755 100.00

3 Area and percentage of forest coverage are slightly different according to data sources and classification of type of land cover.


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6 . 1 F O R E S T C O V E R A G E

Forest distribution is uneven with dense forest in the far north of Ratanakiri (Virachey National Park) and secondary forests (e.g., deciduous, bamboo, shrubland, etc.) between the Srepok and the Sesan Rivers. The eastern Viet Nam border and western Stung Treng border have a mix of evergreen, semi-evergreen and deciduous forests. Agriculture expansion is being linked to forest clearing. The rapid growth of commercial interest as well as the new settlement of outsiders has significantly changed the land use patterns and resulted in apparent soil erosion and microclimate alteration. The changes in areas for rice production and annual cash crop production are presented in Table 15 and Table 16.

Changes in forest coverage in the 3S catchment are believed to be caused by extensive legal and illegal logging, agricultural land expansion, infrastructure development and economic forest concession. Comparing datasets from MRC in 1997 and JICA in 2002, a significant reduction in forest coverage area can be observed. Area covered by evergreen forest and semi-evergreen forest more than halved, from 2 million ha to less than 1 million ha, between 1997 and 2002. On the other hand, area under deciduous forest increased from 50,000 ha to 890,000 ha (Table 17).

Table 13. Changes of land used for rice production (MAFF, 1980-2007).

Year Sekong Sesan Srepok Total 1980 3,542 5,790 7,071 16,403 1985 3,542 7,249 10,079 20,870 1990 3,099 7,134 9,531 19,764 1995 6,199 7,944 10,430 24,573 2000 8,191 11,529 15,982 35,702 2001 8,280 12,379 18,530 39,189 2002 8,590 12,752 17,999 39,341 2003 9,077 13,219 19,254 41,550 2004 9,431 13,409 19,208 42,048 2005 10,184 13,898 20,984 45,066 2006 10,184 15,260 23,009 48,453 2007 10,184 15,844 23,626 49,654 Arable land 34,508 50,158 85,583 170,249

Table 14. Changes of land used for annual cash crop production (MAFF, 1980-2007).

Year Sekong Sesan Srepok Total

1980 126 386 443 955 1995 136 393 488 1,017 1996 138 359 524 1,021 1997 152 326 670 1,148 1998 115 431 585 1,131 1999 185 560 761 1,507 2000 233 493 535 1,260 2001 197 527 716 1,439 2002 173 669 853 1,696 2003 221 676 899 1,796 2004 235 628 918 1,782 2005 393 662 909 1,964 2006 238 1,117 1,518 2,872


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2007 471 1,338 1,818 3,627 Arable land 39,949 58,355 96,952 195,256

Table 15. Changes in land cover in the 3S catchment (MRC, 1997; JICA, 2002).

Land use/cover Year 1997 Year 2002

Area (ha) Percent Area (ha) Percent

Evergreen forest 1,070,300 43.0 458,691 19.0

Semi-evergreen forest 1,091,500 43.8 418,076 17.4

Deciduous forest 50,100 2.0 891,734 37.0

Woodland 212,700 8.5 283,648 11.8

Grassland 9,000 0.4 42,972 1.8

Agricultural land 30,700 1.2 151,559 6.3

Wetland/water 24,100 1.0 24,884 1.0

Urban and others 1,500 0.1 138,589 5.8

Figure 9. Changes in land cover in the 3S catchment

6 . 2 A G R I C U L T U R A L L A N D

Shifting cultivation or slash-and-burn agriculture is commonly practiced by indigenous people living in the catchment. They clear forest land and plant those lands with agricultural crops for 3-5 years depending on soil fertility. Then the area is left abandoned. Their livelihood is usually supplemented with other activities including hunting, fishing and the collection of non-timber forest products (NTFPs).

Common food crops found in the catchment are: rice, sweet potatoes, taro and cassava. Rubber and orchards (e.g., coffee, cashew, mango and oil palm) apparently dominate commercial agricultural land. Besides these, there are annual cash crops: sesame, mung bean, soybean, groundnut and vegetables.

A major constraint on crop production has been limited water availability during the cropping season due to erratic rainfall and limited water management infrastructures. Water is very scarce in the dry season and excessive in the wet season. The main water management tasks in the wet season include


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supplementary irrigation during the dry spell period and flood management to save people’s lives, property and crops.

Along the Sesan River, paddy rice is grown for one crop per year. Paddy fields are flooded with water during the onset of the wet season: when the river gets full, water is channelled into the fields through dikes or pumps. Rice field size per household in general varies from less than 0.5 to 2 ha; some households have up to 5 ha of land (SWECO, 2007). After harvesting the wet season rice, vegetables are grown during the dry season. Irrigation water is carried or pumped up to the gardens from the Sesan River. All cultivation is based on manual labour and neither pesticides nor fertilisers are used.

Among some ethnic minority groups, like the Jarai, smoking is common (both men, women and children can be seen smoking) and tobacco plants are grown on the riverbank as well as further away from the river. In some areas, like in Andoung Meas, many households have started small-scale cultivation of cash crops like soybeans at a distance from the river. Cashew cultivation has also been growing in importance for villagers in Ta Veaeng and Veun Sai. There are private commercial cashew nut and coffee plantations in Ratanakiri, but no ethnic minority people are growing coffee (ADB, 2000).

6 . 3 L A N D U S E R E L A T E D T O A G R I C U L T U R A L A C T I V I T I E S F O R F A M I L Y U S E

Along the Sesan and Srepok Rivers, there are generally three zones of agricultural land in relation to the position of the house and the river: home gardens (around and closest to the house), backyard gardens or crop fields and river bank gardens (only in the dry season) (SWECO, 2007). A high diversity of crop species are grown in these zones. Characteristics of each zone are described below and detailed crop plants in the three zones are presented in Table 18.

- Home gardens are found in the immediate surroundings of almost all homes and are the most diverse of agricultural activities. These usually consist of perennial plants yielding fruits, spices, tubers and vegetables. Annual plants commonly comprise spice plants (coriander, spring onions, Chinese chives), vegetables (long beans, greens of mustard family or Brassicaceae, gourds) and ornamental plants. These provide invaluable plant components for daily use.

- Backyard gardens or crop fields are areas in which many households can have larger areas allocated for crops, like beans, cassava, sweet potatoes, tobacco, sugar cane and, in some cases, also cashew, both for their own use and for commercial purposes.

- River bank gardening was once practiced by most homes during the dry season but has been progressively moved to higher levels due to recent unpredictable fluctuations of the Sesan River.

Paddies and fruit orchards can be found far away from the main rivers. Some secondary crops are also planted in the vicinity of paddy fields. Fruit orchards are more common among villages near the Sesan River than along the Srepok River. The most lucrative orchards were said to be cashew. Rice paddies harvested for one crop per year are most common. Rainfed paddy is grown furthest from the rivers (SWECO, 2007)

6 . 4 A Q U A T I C E C O S Y S T E M S

Aquatic ecosystems in the 3S catchment consist of open water (3S Rivers, its tributaries, small streams and lake) and wetland areas (seasonal flooded forest, grassland, shrubland, marsh and swamp). It is estimated that the total area of aquatic ecosystems for 3S catchment is approximately 352 km2, which covers 1.3% of the total area of the 3S catchment of 26,521 km2.


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Figure 13. Land cover in the 3S catchment

Table 16. List of food and crop plants in Sesan River homesteads (SWECO, 2006).


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Local name Informal translation

Plants grown in the immediate

home gardens

Plants grown in the backyards of

homes

Plants cultivated along the Sesan

River banks "Chi Neangvong" Basil A A - "Chi Angkam" Mint A - - "Chi Vansuy" Coriander A - - "Mtesh" Chili A - A "Sloeuk Krey" Lemongrass A A - "Roum Deng" Galanga A - - "Lmeat" Turmeric A - - "Khgney" Ginger A A - "Sloeuk Khtoem" Spring onion A - A "Khtoem Sor" Garlic A - - "Kroch Chhmar" Lime/Lemon A - - "Sandaek Kuo" Long bean A - - "Sandaek Bay" Mung bean - A -

"Trakoun" Morning glory - - A

"Trob" Eggplant A - A "Lpov" Pumpkin A - A "Trav" Taro A A A "Trasork" Cucumber A - - "Tralach" Long gourd A - - "Nonong" Ridge gourd A - - "Slar" Betel nut A - - "Mlou" Betel leaf A - - "Rumchek" Pandan A - - "Phkar" Flowers A - - "Euloeuk" Watermelon - - A "Paut" Corn - - A "Lngor" Sesame - A A "Manaos" Pineapple A A A "Chek" Banana A - - "L'hong" Papaya A A - "Lamot" Sapodilla A A - "Dong" Coconut A A - "Mean" Longan A A - "Svay Chanty" Cashew A A - "Kroch Thlong" Pomelo A - -

"Kroch Pursat" Green orange A A -

"Ampov" Sugar cane A - - "Seda" Egg fruit A A - "Svay" Mango A A - "Speu" Star fruit A A - "Trabaek" Guava A - - "Khnorl" Jackfruit A A - "Deum Toekdoh "Kor" Milk fruit A A -

"Ampel" Tamarind A A A "Tham Chok" Tobacco - A A "Damlong Cassava A A -


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Chhvea" "Deum Kor" Kapok A A -

7 BIODIV ERS ITY AND NA TION A L RES OU RCES 7 . 1 P R O T E C T E D A R E A S

Virachey National Park, Lumphat Wildlife Sanctuary, protected deep-pools, Yeak Loam lakes and spirit forests are the main protected areas in the 3S catchment. Virachey National Park is the largest (332,500 ha) of seven national parks in Cambodia, located in Stung Treng and Ratanakiri. Specifically, this park is in the ecoregion called the Cambodia/Lao/Viet Nam Tri-border Forests (Baltzer et al., 2001), bordering the Eastern Plains Dry Forests in the south, and its biological importance is rated as Acute to Critical by WWF (SWECO, 2007). In addition, the World Wide Fund for Nature (WWF) has classified the area around the Sesan River as the Forest of the Lower Mekong Ecoregion Complex (FLMEC) forming the Central Indochina Dry Forests (Baltzer et al., 2001). It is also an example of an area of outstanding biodiversity in the Indochina region. Another outstanding protected area in the province is the Lumphat Wildlife Sanctuary, which used to be the Koprey (wild ox) conservation site before the civil war. The sanctuary encompasses evergreen forest, grassy glades, riverine habitats and small wetlands (ADB, 2010a). Another wetland area is the Ramsar site located in the central of Stung Treng along the Mekong River and close to the Lao border (ADB, 2010b).

Virachey National Park (VNP) borders Lao PDR in the north and Viet Nam in the east. The terrain is fairly mountainous with mountain ranges and plateaus from 4,000 m to 1,000 m amsl (average mean sea level). The Sekong and Sesan Rivers run along the eastern and southern edges of the park’s buffer zone. VNP borders with Chu Mom Ray Nature Reserve in Viet Nam and Xe Pian and Dong Ampham National Protected Areas in Lao PDR (SWECO, 2006).

Sixty villages rely on the natural resources of VNP (MoE, 2003). Local people use VNP as village settlements and for swidden agriculture (slash and burn), forest product gathering (rattan, bamboo, malva nuts (Sterculia lychnophora), eaglewood (pieces of Aquilaria crasna) and resin), hunting (rabbits, forest rats, turtles, deer, wild boar), rainfed (wet) rice agriculture and spirit forests4.

Forests provide many significant resources and serve many functions, including: wood products, recreational opportunities, habitat for wildlife, water and soil conservation, and a filter for pollutants. Dense semi-evergreen forest, upland savannah, bamboo thickets and occasional patches of deciduous forest form the majority of the vegetation of VNP. Ashwell (1998) reported 156 vertebrate species of which 43 are of international significance (SWECO, 2006). Wildlife found in VNP is mainly tiger, Himalayan black bear, Malayan sun bear, guar, sambar deer and muntjac (SWECO, 2006). Wildlife in the area that is reported to be highly threatened species are slow loris, pygmy loris, pig-tail macaque, long tailed macaque, douc langur, yellow-cheeked crested gibbon, elephant, tiger, gaur, banteng, other gibbons and langurs (Hout et al. 2003; Baltzer et al. 2001). The Siamese crocodile has also been said to be sighted in tributaries close to the Sesan River.

7 . 2 N O N - T I M B E R F O R E S T P R O D U C T S ( N T F P )

People living in the riverside villages have a long tradition and knowledge in utilising many types of forest products for food, medicine, shelter, household utensils and for generating additional income. Wild vegetables and fruits make an important supplementary food, especially during the dry season between January and June: most fruits ripen from April to June and vegetables, mushrooms and 4 Spirit forests is a part of the forest considered sacred ground and forest graveyards for minority cultures and traditions.


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leaves provide additional sources of protein and minerals to a diet based on fish and rice. Different kinds of leaves and bark are also used for medicine. In addition, wood is collected for firewood and for house construction and the forest provides materials for making baskets and other household crafts. Honey adds to the diet, and resin is collected for sealing boats and making torches for lighting (SWECO, 2007).

Non-Timber Forest Products (NTFP) collected in the Sesan catchment are listed in Table 19 and proportion of vegetation type (% length) along the north and south Sesan River banks is presented in Table 20. There is a notable reduction of wildlife in the 3S catchment including elephant, tiger, deer, native chicken, rabbit, wild pig, peacock, wild cattle and bear. It is reported that the use of guns has intensified as has illegal hunting activity (CNMC, 2009).

Table 17. List of forest products collected by villagers living in the Sesan catchment (SWECO, 2006).

Local name Informal translation Parts used

"Sokram" Xylia dolabriformis

Fungi, timber

"Pchek" Shorea obtuse

Resin, fungi,

timber

"Phset" Mushroom Various parts

"Thnaim Boran"

Medicinal plant

Various parts

"Os" Firewood Various species

"Tompaeng" Bamboo shoot Whole

"Banlae Prey"

Wild vegetable Leaves

"Phdao" Rattan Stem

"Russey" Bamboo Stem "Tnoat" Palm Leaves

Table 18. Proportion of vegetation type (% length) along the north and south Sesan River banks (measured along the Sesan River bank in Cambodia to its confluence with the Srepok River) (Source:

SWECO, 2006).

Vegetation type North bank of Sesan River

South bank of Sesan River

Paddy fields 3 4 Swidden agriculture 16 11 Village garden crops 4 6 Deciduous forest 17 14 Evergreen broadleafed forest 3 10 Riparian forest 0 1 Bamboo and secondary forest 14 9 Mixed forest of evergreen and deciduous species 15 18

Abandoned field covered by shrub 25 22 Woodland and scattered tree (canopy < 10%) 2 3

Shrubland (undifferentiated) 1 - Abandoned field covered by grass - - Sand bar - 2


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In Stung Treng, most families are engaged in collecting NTFPs, which is another important source of supplementary income: some items, such as rattan and resin, are useful for household consumption while the collection of non-timber forest products (NTFPs) is supplements the economic activity of Rattanakiri. In Sesan catchment, the most valuable NTFPs for the rural people in this region are bamboos. Other valuable NTFPs collected by communities include rattan, resin and samrong (native fruit, collected from March to April) and wildlife includes python, snakes, pangolin, giant lizard, wild pigs, deer, wild buffalo, black bird and bee (CNMC, 2009b). The river bank of the Sesan River reportedly serves as habitat for a number of animals: birds, boars, deer, lizards, otters and turtles. Many bird species use the river area for nesting and breeding, particularly during the dry season (Table 21).

Table 19. List of animals hunted by villagers living in the Sesan catchment (Source: SWECO, 2006).

Local name Informal translation Parts used

"Chrouk Prey" Wild boar Whole "Chhlosh" Barking deer Whole "Preus" Sambar deer Whole

"Andeuk" Turtle Body without shell "Trakuot" Monitor lizard Whole "Sampoch" Civet Whole

"Tonsay" Rabbit Whole "Moin Prey" Wild chicken Whole "Kangkaeb" Frog Whole

"Khchang" Snail Body without shell "Trey" Fishes Whole "Chunlen" Earthworm Whole

Logging concessions granted to private corporations covered more than 60,000 ha of forest in Ratanakiri. In January 1998, the Royal Government in Cambodia authorised a 25-year timber concession to the Hero Taiwan Company to log 60,150 hectares of forest in O' Chum, Veun Sai and Taveng districts and logging operations commenced in May 1999 (ADB, 2010a). In April 2000, the Asian Development Bank funded Cambodian Forest Concession Review gave Hero Taiwan Company the lowest performance score of all forest concessions inspected (McAndrew & Il, 2004).

7 . 3 M I N I N G

In Rattanakiri, 22 mining licenses have been issued by the Royal Government of Cambodia (RGC) to 11 companies for extraction of gold, bauxite, iron, gemstones and granite. These companies have a combined total of mining fields of approximately 400,000 ha (ADB, 2010a). Stung Treng contains several mineral deposits but apart from the alluvial gold deposits in the Sekong River (on the border between Stung Treng and Ratanakiri) none are commercially exploited (ADB, 2010b). The mineral resources are reported as follows (3S Basins website, 2010):

- Sand and gravel have been extracted from the river beds of the Sesan in Stung Treng. - Coal deposits are found on the Sekong and Sesan Rivers in Stung Treng.


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- Precious metals, gold and silver resources have been identified on the Sesan and Srepok catchments in Rattanakiri.

- Gemstones, sapphires, amethysts and semi-precious stones such as zircons are found in the lower parts of the Sekong catchment. Rattanakiri in Cambodia is famous for its sapphires, and there are a number of small artisanal zircon mines in the province.

- Base metals like copper and lead minerals have been identified in the Sekong catchment, near Sekong town.

- Bauxite deposits are mainly found in Mondulkiri

7 . 4 F I S H E R I E S

Fish, along with rice, is daily food for all the people residing in the 3S catchment. Traditionally all households engage in fishing, and there are several households in each village that specialise in year-round fishing and selling fish. Table 22 presents the fish catch and fish consumption in this province (ADB, 2010a).

Ninety percent of total population in Stung Treng live along the rivers and streams and rely on fish for food security and subsistence livelihoods. The Fisheries Administration cooperated with the Project of Inventory and Management of Wetland in Cambodia to conduct a study during 1999-2000 and found that there were around 38 sites of fish spawning ground and migration routes in five districts of Siem Pang, Siem Bok, Thalaborivat, Stung Treng and Sesan (Mekong Info, 2010). However, the fisheries resource will be damaged if the illegal fishing activities are not eliminated and if a hydropower dam is constructed at the confluence of the Sesan and Srepok rivers in the future.

In the Sesan catchment, it is reported that natural fish catch has been intensified for trading purposes and has become more difficult for those fishing for household consumption: it takes longer and requires travel further from home (CNMC, 2009). Moreover, illegal fishing has been reported including the use of fine meshed nets, fishing during spawning season and the use of electricity, poisons and explosives (ADB, 2010a). The Yali Falls dam construction had serious negative downstream impacts on fish and fisheries in the Sesan Rivers (Baird and Meach, 2005).

A decline in the fish population is reported to have been especially dramatic since 2000. Recently, many people have stopped fishing due to poor catches. Fish at the provincial Banlung market comes mainly from Kratie, which is from the Mekong mainstream. Some fishermen have moved to work along the Srepok River in southern Ratanakiri, increasing the pressure on this river, where also a decline in fish population has been reported during the past decade.

Table 20. Fish catch and fish consumption in the 3S catchment (ADB, 2010a).

Year Fish catch per capita (kg/capita/year) Annual consumption (kg/person)

Sekong Sesan Srepok Sekong Sesan Srepok

2000 - - - 55 24 18 2002 142 18 29 65 14 31 2003 113 15 25 52 12 28

2004 87 11 19 40 8 23 2007 33 4 4 - - - 2008 105 13 12 - - -

2009 120 12 12 - - -

Average 100 12 17 53 15 25


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8 I N F RA S TRU CTU RE 8 . 1 D O M E S T I C W A T E R S U P P L Y

Ratanakiri and Stung Treng consist of many waterways, including the Sesan and Srepok Rivers, which can serve as fresh water resources in the provinces. The main source of water for villagers is from rivers, lakes, ponds and water wells. However, the water plant is a source of domestic water supply for the provincial towns and this water supply can be consumed only by people who are living around the towns. It is observed that besides the clean water from the water plant and other natural sources of water, in the rainy season, rainwater is commonly used by people in the province. Provincial statistics revealed that 61.1% of residents obtain water from springs, streams, ponds and rain, whereas most of the remainder (32.2%) obtain water from dug wells and only 5.5% of residents obtain water from sources that are considered safe (purchased water, piped water or tube/piped wells) (ADB, 2010a, 2010b).

Six villages in Stung Treng municipality (Srae Pou, Leu, Spean Thma, Kandal, Tra Peang Pring and Preaek villages) have access to tap water. There are about 1,500 water meters (including houses, businesses, offices) connecting to the tap water network. This tap water is pumped from the Sekong in Stung Treng town, which is about 25 km downstream from the planned Lower Sesan 2 Dam site. It is reported that approximately 900 m3 of water is pumped each day, of which 25%-30% is lost through leakage (Baird, 2009).

The Water Supply Authority (semi-autonomous) in Banlung, Ratanakiri had only 525 customers (households) in 2008, which a total volume of 180,000 m3 (or 500 m3/day). The quantity of water supplied to people was equal to 64% of the total volume (36% was used to produce clean water). The water for this water supply plant came from dug wells (ADB, 2010a)

The Nam Theun-Nam Kading basin is unusual in the Mekong basin, in that it sits in line with the track of major annual tropical cyclones. Proximity to the Vietnam coast together with orographic effects from the mountains combines to produce very high annual rainfall and very high variability associated with the presence or absence of typhoon rain. Existing hydroelectric plants in the basin (Nam Theun 2, Nam Gnouang and Theun Hinboun) are characterized by modest or very small storage volumes, which mean that daily rates of rise in reservoirs may be high. Without spillage, rates of rise of 3½ m/d in Nam Theun 2 reservoir are possible during extreme runoff events. This presents challenges for dam operators, for communications between operators of the cascade of dams in the basin, and for extreme reliability of spillway gate mechanisms. There is a great need for improvements to rainfall prediction accuracy over the relatively small area of the basin.

Given the background of ‘close calls’ in the region, with dam overtopping and potential collapse, there is a need for co-ordination and a clear command structure for routing major floods, such as 10-year events, through the Nam Theun-Nam Kading basin. This is a matter of national concern for Laos, and strengthening of emergency preparedness capability in relation to flooding is vital.

8 . 2 T R A N S P O R T

In the 3S catchment, the road infrastructure is very limited and the network does not link to the remote villages along the 3S Rivers and its tributaries. Therefore, local people are heavily dependent on waterway transportation. People use the waterway for fishing, collecting wildlife and forest products, traveling and transporting their agricultural products to the market and bringing back food, household goods and material for construction from the market to their villages. The waterway can


32

also be used to trade with neighbouring communities up and down the rivers (CNMC, 2009). Only small engine boats have been used for daily commuting (ADB, 2010b).

With inadequate port and landing facilities, passengers usually embark and disembark the boats, and cargoes are loaded and unloaded, directly onto the river banks or, in the dry season, on the sand banks. The passengers usually use a very narrow timber plate for moving between the boats and the banks and cargo handling is done in a very basic manner.

8 . 3 E N E R G Y

Stung Treng and Rattanakiri have very sparse population density and no potential industries, therefore, energy demand in these provinces is still very low. The power generation in these two provinces comes from Independent Power Producers and Electricité du Cambodge (EDC). Diesel oil and hydropower plans are used to generate electricity.. The generation capacity and distribution lines in the two provinces are presented in Table 23.

Table 21. Generation capacity and distribution lines in Stung Treng and Rattanakiri in 2007 (Source: EDC, 2008).

9 S OCIO- ECONOM IC P ROF ILE 9 . 1 P O P U L A T I O N S

The 3S Basin covers 14.6% of the country (Cambodia) area and 1.5% of the total population (13.2 million). The catchment covers 48.9% of Mondulkiri, 100% of Ratanakiri and 61.7% of Stung Treng with an estimated total area of 21,055 km2. There are 39,322 households with a total of 193,031 inhabitants living in this subarea. Of these, 3,292 households are headed by women and they account for around 8% of each basin. The size of each household is about five people on average. There are more people in the Sesan Basin (19,315 households and 94,919 inhabitants) and the Srepok Basin (16,101 households and 77,799 inhabitants), than in the Sekong Basin (3,906 households and 20,331 inhabitants). The population density in this subarea is very low (seven people per km2) when compared to other parts of Cambodia. Population density in 47 out of 72 communes within this catchment is less than 20 people per km2. The population is mainly concentrated in the provincial towns or places not so far from the town. The annual population growth is 1.7%. This figure includes migration, which has been increasing significantly in the last five years. If only local population is included the growth rate is lower due to high infant mortality (SWECO, 2007).

Data in Table 24 indicates that there is similar proportion of males and females in most age groups in the whole catchment as well as in each basin. 43.1% of the population is young (under 15) and approximately 52.5% of the population is working age (15-60). This means that more jobs need to be ensured(CNMC, 2009).

For the 3S Basins, the term “ethnic minority” appears to be a misnomer because the ethnic population outnumbers the Khmer people (Table 25). In fact, Khmer people represent only 18.3%

Province Diesel oil (GWh)

HPPs (GWh)

Total (GWh)

Medium voltage line length (km)

Low voltage line length (km)

Number of substation

Stung Treng 2.563 - 2.563 13.073 33.812 12 Rattanakiri 1.796 3.209 5.005 21.690 31.340 19


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(35,347) of the total population for this subarea. Significant ethnic minorities include Charay, Cham, Kachak, Kavet, Kroeung, Lao, Phnong, Praov and Tompuon (CNMC, 2009).

Tompuon is the largest minority group and accounts for just over 20% of the ethnic population. Charay, Kroeung and Phnong account for more than 30% of the ethnic population. Historically, Cham and indigenous ethnic people have lived in this catchment for centuries while the Khmer, Lao and Vietnamese have only recently settled in this remote area. Overall, recent statistics from the Commune Database (2007) reveal that there are 26 ethnic groups within the 3S Basins. Of these, 13 ethnic groups account for nearly 80% of the ethnic population (CNMC, 2009).

Table 22. Population and age group (Commune Database, NIS, 2008).

Age group Sekong Sesan Srepok 3S catchment

Female Male Female Male Female Male Female Male Both Aged 0-2 771 751 3,575 3,397 2,692 2,700 7,038 6,848 13,886 Aged 3-4 777 794 3,663 3,878 2,885 3,388 7,325 8,060 15,385 Aged 5-6 2,514 2,309 11,273 11,040 10,090 9,796 23,877 23,145 47,022 Aged 7-11 896 800 4,631 4,371 3,501 3,722 9,028 8,893 17,921 Aged 12-14 708 708 3,161 3,023 2,463 2,605 6,332 6,336 12,668 Aged 15-17 505 488 2,235 2,205 1,785 1,885 4,525 4,578 9,103 Aged 18-24 522 523 2,574 2,467 1,845 1,749 4,941 4,739 9,680 Aged 25-35 1,226 1,200 5,398 5,493 4,431 4,648 11,055 11,341 22,396 Aged 36-45 759 719 3,390 3,357 2,686 2,886 6,835 6,962 13,797 Aged 46-60 1,296 1,197 5,958 5,370 4,604 4,352 11,858 10,919 22,777 Aged over 61 456 394 2,241 2,219 1,517 1,569 4,214 4,182 8,396

Total 10,430 9,883 48,099 46,820 38,499 39,300 97,028 96,003 193,031

Table 23. Composition of population groups within the 3S catchment (Commune Database, NIS, 2008).

Groups Sekong Sesan Srepok 3S catchment

Khmer 16,732 14,154 4,462 35,348 Non-Khmer 3,581 80,765 73,337 157,683

Charay 16 13,161 8,479 21,656

Cham 6 343 2,119 2,468

Kachak 9 3,585 6 3,600

Kavet 3,015 3,264 37 6,316

Kroeung 3 16,420 3,326 19,749

Lao 3 9,432 2,201 11,636

Phnong 0 6 14,368 14,374

Praov 23 6,879 1,753 8,655

Tompuonn 21 15,453 16,312 31,786 Others 485 12,222 24,736 37,443

Population 20,313 94,919 77,799 193,031


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9 . 2 A C C E S S T O P U B L I C S E R V I C E S

This section describes access to public services and Table 26 presents about population and access to different public services.

9 . 2 . 1 A c c e s s t o s a f e w a t e r

People living in the 3S catchment have the poorest access to safe water in Cambodia. Overall, only 41.2% of the households living in the catchment can access safe water (tap/pipe water) (CNMC, 2009).

9 . 2 . 2 A c c e s s t o s a n i t a t i o n

Less than 10% of households living in the 3S catchment use toilets. At the catchment level, the percentage of households using toilets ranges from 7.7% (in Sesan catchment) to 12.7% (in Sekong catchment). Generally, only people living in or near provincial towns use a toilet, whereas most households in rural areas do not have one because they are still living an indigenous lifestyle (CNMC, 2009).

9 . 2 . 3 A c c e s s t o h e a l t h c a r e

In every district of the Sesan catchment there is a District Health Centre with health counselling staff and midwives but no medical doctors. The doctors are regularly available only at the provincial hospital. Currently, a health care structure of health posts at commune level is being established in Ratanakiri to bring a basic health care closer to villages (SWECO, 2007).

9 . 2 . 4 I l l i t e r a c y

The illiteracy rate in the 3S catchment is very high when compared to other parts of Cambodia. Overall, 52% of people aged 15-60 living in the 3S Basin are illiterate. At the basin level, the illiteracy rate ranges from 44% (Srepok) to 64% (Sekong). At the commune level, 48 out of 72 communes in the SA-7C have an illiteracy rate of 50% or more. At the village level, 217 out of 328 villages have an illiteracy rate of 50% or more. Of these, there are 37 villages with 100% of population illiterate (CNMC, 2009).

9 . 2 . 5 A c c e s s t o l a n d r e s o u r c e s

Land is a critical asset for rural people in the 3S catchment as well as in the whole country. At the subarea level, more than 90% of the households have at least 1 ha of rice land each. With a population density of eight people per km2, which is very low when compared to other parts of Cambodia, access to cultivated land is much easier, particularly in very remote areas. However, recent developments (logging, land concession, etc.) are very likely creating landlessness problems. Problems related to land access will be aggravated in the next 20 years as the population grows. This poses a great challenge for water and related resources planning, particularly for addressing poverty of the rural poor (CNMC, 2009). Land concessions are becoming a hot issue due to conflicts created from granting decisions. As of 2009, a total of 929,798 ha of land within the 3S Basins were granted by the government to private companies as concession land. Of these, 298,482 ha were under long-term (70 years) economic land concessions and 631,316 ha were under mining concessions. Some of these lands overlap indigenous community land or land that they used (CNMC, 2009).

Table 24. Demography of 3S Basins (Commune Database, NIS, 2008).

Sekong Sesan Srepok 3S catchment

Population 20,313 94,919 77,799 193,031

Mondulkiri - - 20,685 20,685

Ratanakiri - 85,029 53,775 138,804

Stung Treng 20,313 9,890 3,339 33,542


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Female population 10,430 48,099 38,499 97,028

Mondulkiri - - 10,351 10,351

Ratanakiri - 43,098 26,477 69,575

Stung Treng 10,430 5,001 1,671 17,102 Number of households 3,906 19,315 16,101 39,322

Mondulkiri - - 4,364 4,364

Ratanakiri - 17,107 11,075 28,182

Stung Treng 3,906 2,208 662 6,776 Number of households whose heads are female 273 1,547 1,472 3,292

Mondulkiri - - 483 483

Ratanakiri - 1,358 942 2,300

Stung Treng 273 189 47 509 Households with cultivated land less than 1 ha 8 134 207 349


Ratanakiri - 134 108 242

Stung Treng 8 0 11 19 Households with no cultivated land 12 49 107 168


Ratanakiri - 49 70 119

Stung Treng 12 0 1 13 Households with rice land less than 1 ha 258 1,501 720 2,479


Ratanakiri - 1,320 253 1,573

Stung Treng 258 181 59 498 Households with no rice land 354 1,360 781 2,495


Ratanakiri - 1,196 591 1,787

Stung Treng 354 164 20 538 Households with access to clean water 1,609 6,391 4,811 12,811

Mondulkiri - - 1,909 1,909

Ratanakiri - 5,513 2,678 8,191

Stung Treng 1,609 878 224 2,711 Households using toilettes 495 1,495 1,885 3,875


Ratanakiri - 1,035 1,768 2,803

Stung Treng 495 460 44 999 Households with access to electricity 184 1,472 2,227 3,883


Ratanakiri - 1,472 2,057 3,529

Stung Treng 184 0 0 184 Children aged 6-24 attending school 4,367 16,094 17,850 38,311

Mondulkiri - - 4,860 4,860

Ratanakiri - 13,982 12,042 26,024

Stung Treng 4,367 2,112 948 7,427 Illiterate people aged 15-60 6,690 27,639 18,196 52,525

Mondulkiri - - 4,762 4,762

Ratanakiri - 26,027 12,830 38,857

Stung Treng 6,690 1,612 604 8,906


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1 0 D EV ELOP M EN T TREN DS IN TH E 3S CA TCH MEN T

This section describes the development of large infrastructure in the 3S Basin in Cambodia. Only two development trends are found in the area: agriculture (irrigation) and hydropower.

1 0 . 1 I R R I G A T I O N D E V E L O P M E N T

In the 3S River Basin, there are a total of 82 existing irrigation projects which were built during the Khmer Rouge regime (8 schemes in Sekong Basin, 39 in Sesan and 35 in Srepok), of which only 8 schemes are functional and operational (Table 27). The 82 schemes, if running, have the potential to irrigate 2,803 ha in the dry season and 14,878 ha in the wet season (Table 28). Actually, only 520 ha are irrigated in the dry season. Most irrigation schemes are small-scale schemes able to irrigate 180 ha on average. Only three schemes have the potential to irrigate more than 1,000 ha. Most schemes were built and used for providing supplementary irrigation water to the wet season crop production. All schemes use water from small reservoirs filled with rainfall during the rainy season. Those reservoirs have very limited capacity for providing water during the dry season (ADB, 2006). Current condition of rice production in the 3S catchment is presented in Table 29.

Table 25. Irrigation schemes in the 3S catchment (NCDD of Mondulkiri, Ratanakiri, Stung Treng, 2009).

Catchment Mondulkiri Ratanakiri Stung Treng Total

Existing schemes Sekong - - 8 8

Sesan - 34 5 39

Srepok 10 24 1 35 3S catchment 10 58 14 82

Operating schemes

Sekong - - - -

Sesan - 3 - 3

Srepok 2 3 - 5 3S catchment 2 6 - 8

Table 26. Potential irrigation area in the 3S catchment (NCDD of Mondulkiri, Ratanakiri, Stung Treng, 2009).

Catchment Season Mondulkiri Ratanakiri Stung Treng Total

Sekong Dry - - 970 970

Wet - - 2,700 2,700

Sesan Dry - 698 490 1,188

Wet - 2,911 1,100 4,011

Srepok Dry - 595 50 645

Wet 6,073 1,944 150 8,167

3S catchment Dry - 1,293 1,510 2,803

Wet 6,073 4,855 3,950 14,878


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Table 27. Current condition of rice production in the 3S catchment (NCDD of Mondulkiri, Ratanakiri, Stung Treng, 2009).

Catchment Wet season Dry season

Area (ha) Yield (t/ha) Production (t) Area (ha) Yield (t/ha) Production (t) Sekong 19,642 1.4 26,517 20 1.6 31 Sesan 8,598 1.2 10,404 - - - Srepok 32,753 1.1 36,683 500 1.4 715 Total/Average 60,993 1.2 73,604 520 1.5 746

Specifically, the irrigation projects in the Sesan are of small scales type and use runoff water, and some are under consideration for improvement and rehabilitation by the Provincial Department of Water Resource and Meteorology (PDOWRAM). As the construction of the irrigation schemes during the Khmer Rouge regimes was not based on Integrated Water Resources Management (IWRM), the rehabilitation or improvement of the existing projects require a better study and application of the IWRM principle in order to build more sustainable irrigation projects (CNMC, 2009).

Based on the analysis of the water and related resources, particularly land, soil types, elevation and overall geographical conditions of each tributary, six small and medium scales potential irrigation projects in the Sesan can be identified (CNMC, 2009). Table 30 presents potential schemes, its irrigable area and its additional components for project implementation.

Table 28. Potential irrigation development in the Sesan Basin.

Potential

Irrigable area (h )

Additional components Lower Sesan 2 14,211 7,586 ha with 60 m elevation. 5,257 ha with 75 m and 1,368 ha with

Prek Chhnang 2,790 N/A O Kansieng 5,059 N/A Prek Lalai 997 Integrated with 24 km of flood protection embankment Prek Lamang 2,005 Integrated with 16 km of flood protection embankment Prek Liang 3,066 Integrated with 3 km of flood protection embankment

1 0 . 2 H Y D R O P O W E R D E V E L O P M E N T

It is obvious that the planned dams in Viet Nam are being implemented, whilst the dams in Cambodia are still at the planning and design stages. On the Sesan River in Cambodia, potential annual energy is planned to be 4,176 GWH. Currently, only O Chum 2 is in operation with capacity of 3 GWH.

Based on the Lower Mekong Basin (LMB) Hydropower Sector Review, there are a total of four large scale projects located in the Sesan catchment, and among them the Lower Sesan & Srepok 2 is the most significant in term of economic viability since the annual revenue expected is high (14% of investment cost) (CNMC, 2009). Table 31-Table 33 present potential hydropower development in the Sesan Basin.

In addition, there are three more potential micro hydropower plants in the Sesan Basin. They are O Chum 3 (74 kW), Ta Ang (10 kW) and Bei Srok (78 kW). Furthermore, there is one state-owned hydropower plant, O Chum 2, which is under operation with a capacity of 1 MW (ADB, 2006).

Table 29. Potential hydropower development in the Sesan Basin (CNMC, 2009) (1 of 3).

Dam name River Catchment

size (km2)

Monthly flow (m3/s)

Spillway design max flow

(m3/s)

Base flow

(m3/s)


38

Sesan 1 Mainstream 11,070 N/A 24,163 21 Ochum 2 Tributary 45 2 278 0 Prek Liang 1 Tributary 883 N/A 2,234 2 Prek Liang 2 Tributary 595 N/A 2,934 3 Lower Sesan 3 Mainstream 15,600 N/A 28,488 44 Lower Sesan 2 Mainstream 49,200 1,304 36,394 132


Dam name Sediment (‘000 m3)

Draw down

(m)

Res. area (km2)

Gross sto. (mil. m3)

Active sto. (mil. m3)

People resettled

Sesan 1 NA 1.0 10.6 37.7 3.4 0 Ochum 2 NA 2.5 0.1 - 0.1 0 Prek Liang 1 47 20.0 10.7 170.8 134.6 N/A Prek Liang 2 36 10.0 5.6 100.5 54.7 N/A Lower Sesan 3 163 1.0 414.0 4,542.4 323.1 6,035 Lower Sesan 2 201 1.0 312.4 1,792.5 279.8 3,985


Dam name Height (m)

Length (m)

Discharge (m3/s)

Head (m)

Capacity

(MW)

Annual energy (GWH)

Annual revenue

(%) Project status

Sesan 1 32 644 N/A 18.6 90 480 - N/A

Ochum 2 10 107 4 32.6 1 3 - Under-operation

Prek Liang 1 90 300 27 154.0 64 259 7.59 Pre-feasibility study

Prek Liang 2 90 250 18 106.0 64 261 6.92 Pre-feasibility study

Lower Sesan 3 75 4,320 500 27.0 180 953 8.11 Pre-feasibility study

Lower Sesan 2 36 6,036 2,119 22.2 400 1,912 14.04 Feasibility study

1 0 . 3 A C O N T R O V E R S I A L P R O J E C T : L O W E R S E S A N 2

Although the Environmental Impact Assessment report on the Lower Sesan 2 hydroelectric dam did not meet the international best practice on dam development, the Royal Government of Cambodia (RGC) has approved the controversial project.

The Lower Sesan 2 Project was found to cause tremendous impact on the fisheries and biodiversity of the Tonle Sap and Mekong system. The project would cause about 9% drop in fish stocks and threaten more than 50 fish species in the Mekong Basin (Ziv et al., 2012).

The design of the Lower Sesan 2 dam has been revised several times and unclosed to the public. It is recently reported that the dam would equipped with an installed capacity of 400 MW and would have a length of 6 km, a height of 36 m and a reservoir area of 312 km2.

The time line of the development of the Lower Sesan 2 Project are given as follows (Mekong Watch, 2013):

- June 2007: A Memorandum of Understanding (MOU) was signed between Electricité du Viet Nam (EVN) and Ministry of Industry, Mines, and Energy (MIME), on behalf of the Royal Government of Cambodia, for EVN to undertake a feasibility study.


39

- 2008 to 2009: A feasibility study was conducted by an EVN subsidiary, the Power Engineering Consulting Joint-Stock Company No 1 (PECC1).

- January to June 2008: Environmental Impact Assessment (EIA) on the Lower Sesan 2 project was conducted by the Key Consultants Cambodia (KCC).

- June 2010: The EIA report was approved by the Royal Government of Cambodia. - April 2011: The Cambodia-Vietnam Hydropower Company, a joint venture between the Royal

Group (49%) and EVN International Joint Stock Company (EVNI) (51%), was established as the dam’s developer. It was later registered as the Hydro Power Lower Sesan 2 Co. Ltd., by the Royal Group.

- November 2012: the Lower Sesan 2 Project was approved by the Royal Government of Cambodia. A joint agreement for the dam’s construction was signed between the Royal Group and Hydrolancang International Energy.

- February 2013: The Law on Government Guarantee of Payment for the Lower Sesan 2 Project was approved by Cambodia’s National Assembly.

- March 2013: The Ang & Associates Lawyer Co. Ltd., owned by the Royal Group had begun clearing the dam's reservoir.

1 1 A G EN CIES W ITH F UN CTI ON S A FF ECTING W A TER RES OU RCES D EV ELOP MEN T

This table presents the agencies (in their respective ministry), which are directly involved in water resources management in Cambodia (WEPA, 2013). Ministry/Agency Function Ministry of Water Resources and Meteorology (MOWRAM) The Ministry of Water Resources and Meteorology is given the following mission by the Royal Government of Cambodia:

- Define and develop policies and strategies towards the utilisation, development and sustainable conservation of water resources.

- Study and research potential water resources in terms of surface, underground and atmosphere in order to establish the basic scientific techniques.

- Develop short, medium and long term plans for exploration, development and conservation of water resources and atmosphere.

- Manage all direct and indirect utilisation of water resources and disaster minimisation.

- Develop legislations related to water resources management and their application.

- Provide necessary technical support and advice to private sectors, organisations, communities and all people who are related to the improvement and exploitation of water resources.

In the context of water resource management, there are two departments directly involved: the Department of Hydrology and River Works and the Department of Water Resources Management and Conservation.


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Department of Hydrology and River Works

(1) Research and Flood Forecasting Office

(2) Hydrological Works Office

(3) Water Quality Analysis Office

(4) River Works and Bank Protection Office

(5) Administration Office

- Develop necessary projects and hydrological stations at designated water areas in order to serve the water resources development.

- Develop short, medium and long term plans for erosion, sedimentation and river bank protection and management.

- Observe the hydrological regime both surface and groundwater by establishing hydrological stations and collecting and analysing data for related sectors.

- Measure and evaluate the water level, discharge, sedimentation and other related tasks.

- Monitor water quality at the hydrological stations of the designated water areas along the Mekong River, Tonle Sap Lake and their tributaries.

- Research and study the hydrological phenomena, hydrological modelling, hydrological calculation and the potential of surface and ground water.

- Manage the hydrological information and forecast and provide information before floods and water shortages.

Department of Meteorology

(1) Forecasting Office (2) Equipment Office (3) Observation Office (4) Climate Office (5) Administration Office (6) Information and

research Office

- Develop necessary projects and meteorological stations in the country.

- Observe, collect and analyse the weather conditions for the purpose of serving all concerned sectors.

- Report climate observations and information. - Forecast weather across the country. - Research on natural disaster phenomena related to

the climate and seismology.

Department of Water Resources Management and Conservation

(1) Administration Office (2) Water Policy and

Extension Office (3) Hydropower and Flood

Control Office (4) Water Management

Office

- Develop and carry out the strategic plans for various development activities, e.g., hydropower, flood control, irrigation.

- Manage watershed areas and develop relevant programmes for ensuring the utilisation and conservation of water resources in an effective and sustainable manner.

- Develop necessary policies, legislations and regulations for policymakers.

Ministry of Environment (MoE) The Ministry of Environment has the following critical functions;

- Collect and collate related data about water quality at public water areas and pollution sources.

- Assess the status of the water environment and natural resources (current status and future trend) based on existing data.

- Prepare specific legislation for environmental protection and natural resources


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management. - Issue a license of treated wastewater discharge to factories that have been

recognised as having complied with the national effluent water quality standard imposed by the ministry.

The most important department directly involved in water resources development is the Department of Environmental Pollution Control. Department of Environmental Pollution Control

(1) Office of Water and Soil Quality Management

(2) Office of Environmental Pollution Research and Technology Management

(3) Office of Planning and Statistics

(4) Office of Air Quality, Noise and Vibration Management

(5) Office of Laboratory and Analysis

(6) Office of Soil Waster and Hazardous Substance Management

(7) Office of Administrative and Staff Governing

- Monitor and control effluents and/or treated effluents discharged from various pollution sources into receiving sources.

- Monitor and control water quality at public water areas in compliance with the Public Water Quality Standard for Biodiversity Conservation, and report to the decision-makers about the current water quality aspect and its future trend.

- Cooperate and implement the international conventions approved by the Royal Government.

Ministry of Agriculture and Forestry (MAFF) The Ministry of Agriculture, Forestry and Fisheries has the following function and roles:

- Develop policies, and coordinate, monitor and evaluate the implementation of policies and development programmes in the agriculture sector.

- Create legislation and regulations on the agricultural management and maintain and protect the natural resources under the agricultural sector.

- Provide necessary support and advice to farmers and key stakeholders on technologies to improve production and increase productivity.

- Conduct research study on advanced agricultural technology, science and economics for all sub-sectors.

- Provide advice on agricultural land development, soil quality improvement and appropriate utilisation of land, seeds, breeds, fertiliser and chemicals according to the conditions of geography and regional climate, which leads to high yield and maintains the balance of the environment.

There are three departments directly involved: the Fisheries Administration, the Inland


42

Fisheries Research and Development Institute and the Forestry Administration.

Fisheries Administration

(1) Administration-personnel Division

(2) Planning-accounting Division (Project Management Division)

(3) Fishing Domain and Extension Division

(4) Litigation Division (Community Fishery Development Division)

(5) Exploitation Division (6) Aquaculture Division

(Inspection and Surveillances Division)

(7) Fisheries Inspection Units/Stations (Provincial Fisheries Division)

- Prepare and establish fishery resource inventory, assess potentiality and follow up on the evolution of fishery resources and aquaculture.

- Create laws and regulations for fishery protection and fishery resource exploitation management and monitoring.

- Prepare plan to manage fishery zones and fishery conservation and set up fishery resource development policies and measures which ensure environmental protection.

- Conduct scientific research study on fishery and aquaculture.

- Inspect and manage all activities of fishery resource exploitation and aquaculture.

Inland Fisheries Research and Development Institute (IFReDI)

(1) Biological Division (2) Laboratory Division (3) Techno-transfer

Division (4) Socio-economic

Division (5) Field Research Station (6) Administrative Division

- Scientific collection, analysis and dissemination of biological and socioeconomic data.

- Development and upgrading of national capacity for the rational management of inland fisheries.

- Maximisation of the income of fishermen and farmers. - Sustainable utilisation of the fishery resources.

Forestry Administration - Prepare forest and wildlife inventory and assess potentiality and follow up forest and wildlife evolution.

- Create laws and regulations for the protection and management of forestry resource exploitation and wildlife conservation.

- Take part in the establishment of measures to ensure environmental protection and prepare plan for forestry zoning management, natural protection zones and reforestation areas and set up forestry and wildlife development policy.

- Conduct scientific research and studies on forestry and wildlife.

- Inspect and manage the exploitation activities on


43

forestry and wildlife hunting.

Ministry of Industry, Mines and Energy (MIME) The Ministry of Industry, Mines and Energy has the following mandate and duties:

- Develop policies for proper management of industry, mine and energy sectors. - Manage and enhance technologies and standards. - Develop and carry out the national policy on research studies on mineral resources

and other natural resources (in terms of both in land and water) and hydropower. - Encourage and develop privatisation procedures within a clean water supply and

sanitation sector.

Department of Hydropower - Develop and implement the national policy of electric power including low cost electric power, effective uses and making electricity available in most urban and rural areas.

- Collect, analyse, maintain and utilise data for study and develop hydro-electric power in potential areas with sound environment.

- Develop and implement the action plan of hydro-electric power development throughout the country, including its monitoring programme.

Department of Portable Water Supply

- Control and manage the production and utilisation of safe water throughout the country.

- Collect information and make inventory on the potential production of water and supply, both surface water and groundwater.

- Develop policies, rules and regulations to manage water supply and sanitation.

- Prepare and install specific laboratories to control water quality, based on the National Drinking Standard.

Cambodia National Mekong Committee (CNMC) As a governmental institution, the Cambodia National Mekong Committee has the following major functions:

- Coordinate, collaborate with, advise and follow up with relevant divisions of the ministries concerned and line agencies, in order to implement all government decisions related to the Mekong River and its tributaries.

- Strengthen the cooperation with other members of the National Mekong Committee, donors and international organisations in order to research, study, design, develop, manage and maintain water and related resources, including water quality.

Ministry of Rural Development (MRD) The Royal Cambodian Government has given the Ministry of Rural Development complete responsibility within Cambodia for these following Rural Development initiatives and activities:


44

- Coordinating, Cooperating, Implementing, Monitoring and Evaluating Rural Development Projects and Programs in order to rehabilitate and help develop the country's Rural areas by assisting the Rural population.

- Coordinating the operational efforts of the various Line Ministries and assistance programs.

- Actively Undertaking Independent Research Initiatives to practically develop the Rural areas of Cambodia by liaising widely, in order to assess likely needs and investigate possible solutions that would maximize identified opportunities, etc.

Department of Rural Water Supply

- To prepare short/medium/long-term plans for the rehabilitation and development of small-scale irrigation systems at the family, village and commune levels and small-scale energy projects as well as clean water supply programs;

- To survey, research, design and carry out small-scale irrigation projects at the family, village and commune levels and small-scale energy projects as well as clean water supply program in collaboration with relevant institutions;

- To monitor and ensure the quality of wells and well-water before villagers are free to use it daily; and

- To prepare and produce documents covering operation and maintenance for small-scale irrigation and clean water, and the organization of water user's association.

Ministry of Public Works and Transportation (MPWT) In relation to the water environmental management process, the Ministry of Public Works and Transport has the following mandates and functions:

- Develop specific national policy concerning all public works construction by establishing the principles of law, relevant regulations and cooperation with various organisations.

- Build, maintain and manage all the infrastructures of roads, bridges, ports, railways and waterways.

Department of Waterways - Study and execute works concerning waterways and navigations in natural watercourse.

- Prepare acceptable locations for the rafts and floating houses and examine the construction of structures along the river.

- Study and research the river bank subsidence and its protection.

- Propose measures and dredge the river so that it will be deep enough to be used for transport.

- Examine the requests to pump water from and into rivers which may alter the water depth.

- Monitor the water level of all the rivers in the country for navigation purposes.


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1 2 REF EREN CES

3S Basins website, 2010. http://reta.3sbasin.org/, accessed on October 31, 2010.

3S Rivers Protection Network (3SPN), 2010. http://3spn.cfsites.org, accessed on October 31, 2010.

Ashwell, D. 1998. The Conservation and Management of Biological Resources and Values of Virachey National Park. A Report to the World Bank for Biodiversity and Protected Areas Management Project, Cambodia, World Bank, Washington.

Asian Development Bank (ADB), 2000. ADB RTA 5771. Draft July 2000. Poverty Reduction and Environmental Management in Remote Greater Mekong Subregion Watersheds. Phase II. Interim Report Volume II: Opportunities for Project Interventions: Cambodia – Se San. Margules Pöyry in association with ANZDEC Ltd, New Zealand and GFA-Agrar, Germany.

Asian Development Bank (ADB), 2006. Sesan, Srepok, and Sekong River Basins Development Study in Kingdom of Cambodia, Lao People's Democratic Republic, and Socialist Republic of Viet Nam, ADB.

Asian Development Bank (ADB), 2010a. 3S River Basin – Provincial Sector Development Briefing Note, Rattanakiri Province.

Asian Development Bank (ADB), 2010b, 3S River Basin – Provincial Sector Development Briefing Note, Steung Treng Province

Baird, I.G., 2009. Best Practices in Compensation and Resettlement for Large Dams: The Case of the Planned Lower Sesan 2 Hydropower Project in Northeastern Cambodia. Rivers Coalition in Cambodia, Phnom Penh.

Baird, I.G., and Meach, M., 2005. Se San river fisheries monitoring in Ratanakiri province, Northeast Cambodia. Before and after the construction of the Yali Falls Dam in the central highlands of Vietnam.

Baltzer, MC, Nguyen Thi Dao, RG Shore (eds.), 2001. Towards a vision for biodiversity in the forest of the lower Mekong ecoregion complex – technical annex. WWF Indochina/WWF US, Hanoi and Washington D.C.

Cambodia National Mekong Committee (CNMC), 2009a. Profile of Sub-area 7C (Cambodia), October 2009.

Cambodia Nation Mekong Committee, 2009b. Proceedings of 3S Basin Consultation Workshop, Cambodia National Mekong Committee, November 2009.

Danith, C. 2001. Community Forestry in the Watershed of Ratanakiri province, Cambodia.

Electricite du Cambodge (EDC), 2008. EDC Annual Report 2007, EDC 2008.

Hout S. K., Pech B., Pool M. C., Tordoff W. A., Davidson P., Delattre E., 2003. Directory Important Bird Areas in Cambodia. Key Sites For Conservation. Phnom Penh 69-74.

McAndrew J.P and Oeur Il, 2004. Upholding Indigenous Access to Natural Resources in Northeast Cambodia. Indigenous Peoples and Communal Land Management in Asia Regional Workshop at ADB Headquarters, Manila.

Mekong Info, 2010. Status of Fisheries Resources in Stung Treng Province. http://www.mekonginfo.org, accessed on September10, 2010.

Mekong Watch, 2013. Fact Sheet – Lower Sesan 2 Hydropower Project, Northeastern Cambodia, Mekong Watch and 3S Rivers Protection Network.


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Ministry of Environment (MoE), 2003. Virachey National Park, Management Plan 2003-2007. Phnom Penh.

National Institute of Statistics (NIS), 2008. Cambodia General Population Census 2008, Retrieved from web http://celade.cepal.org/khmnis/census/khm2008/, accessed on July 15, 2010.

National Committee for Sub-National Democratic Development (NCDD) of Mondulkiri, 2009. Mondulkiri Data Book 2009.

National Committee for Sub-National Democratic Development (NCDD) of Ratanakiri, 2009. Ratanakiri Data Book 2009.

National Committee for Sub-National Democratic Development (NCDD) of Stung Treng, 2009. Stung Treng Data Book 2009.

SWECO Groner (in association with Norwegian Institute for Water Research, ENVIRO-DEV, and ENS Consult, and Electricity of Viet Nam), 2006. Environmental Impact Assessment on the Cambodian part of the Se San River due to Hydropower Development in Vietnam, December 2006.

Water Environment Partnership in Asia (WEPA), 2013. http://www.wepa-db.net/policies/structure/chart/cambodia/index.htm, accessed on January 31, 2013.

Ziv, G., Baran, E., Nam, S., Rodríguez-Iturbe, I., and Levin, S., 2012. Trading-off Fish Biodiversity, Food Security and Hydropower in the Mekong River Basin, Proceedings of the National Academy of Sciences of the United States of America.

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