basin profile of the nam theun/nam kading, nam hinboun … · this report covers the catchment of...

MK3

Optimising cascades of hydropower

BASIN PROFILE

BASIN PROFILE OF THE NAM THEUN/NAM KADING, NAM HINBOUN AND XE BANG FAI IN LAO PDR

October 2013 Khamfeuane Sioudom

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Author Khamfeuane Sioudom

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 Sioudom, K. 2013. Basin Profile for the Nam Theun/Nam Kading, Nam Hinboun and Xe Bang Fai, Lao PDR. 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: Nam Theun river downstream of the Nakai dam (Nam Theun 2) (Photo Peter-John Meynell). Inside page: Downstream of the Nam Ngouang dam (still under construction) (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 6A Lane 49, Tô Ngoc Vân| Tay Ho, HA NOI | Socialist Republic of Viet Nam

http://www.optimisingcascades.org/

http://www.icem.com.au/

MEKONG CPWF| Optimising cascades of hydropower (MK3) Basin Profile of the Nam Thuen-Nam Kading in Lao PDR

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TA BLE OF CON TEN TS 1 ACKNOWLEDGEMENTS ........................................................................................................................... 4 2 INTRODUCTION ....................................................................................................................................... 5 3 BOUNDARIES OF THE BASIN .................................................................................................................... 6 3.1 Nam Theun/Nam Kading ............................................................................................................................ 9 3.2 Nam Hinboun ............................................................................................................................................. 9 3.3 Xe Bang Fai ................................................................................................................................................. 9 4 PHYSICAL CHARACTERISTICS ................................................................................................................. 10 4.1 Topography and geology .......................................................................................................................... 10 4.1.1 Nam Theun/Nam Kading .................................................................................................................... 12 4.1.2 Nam Hinboun ...................................................................................................................................... 12 4.1.3 Nam Gnouang Reservoir and Dam site ............................................................................................... 12 4.2 Soil ............................................................................................................................................................ 13 4.3 Seismicity ................................................................................................................................................. 13 4.4 Climate ..................................................................................................................................................... 14 4.4.1 Temperature ....................................................................................................................................... 14 4.4.2 Rainfall ................................................................................................................................................ 14 4.4.3 Evaporation ......................................................................................................................................... 15 4.5 Hydrology ................................................................................................................................................. 15 4.5.1 Nam Hinboun/Nam Hai ...................................................................................................................... 17 4.6 River geomorphology and drainage network .......................................................................................... 19 4.7 Water Quality ........................................................................................................................................... 20 4.7.1 Sub Basin Characteristics .................................................................................................................... 20 4.7.2 Heavy metals ...................................................................................................................................... 22 4.7.3 Oxygen Status ..................................................................................................................................... 22 4.7.4 Stratification ....................................................................................................................................... 23 5 BIOLOGICAL ENVIRONMENT ................................................................................................................. 23 5.1 Terrestrial habitats, land use and vegetation cover ................................................................................ 23 5.1.1 Nam Gnouang catchment ................................................................................................................... 23 5.2 Wildlife ..................................................................................................................................................... 25 5.2.1 Regional Status ................................................................................................................................... 25 5.2.2 Nam Gnouang catchment ................................................................................................................... 26 5.2.3 Nam Hai and Nam Hinboun Catchment ............................................................................................. 27 5.3 Aquatic Ecology ........................................................................................................................................ 27 5.3.1 River Ecology ....................................................................................................................................... 27 5.3.2 Aquatic Biodiversity ............................................................................................................................ 29 5.3.3 Fish Production ................................................................................................................................... 30 6 LAND COVER AND LAND USE ................................................................................................................. 32 6.1 Land cover related to agricultural activities ............................................................................................. 33 6.2 Forest ....................................................................................................................................................... 33 6.3 Agriculture................................................................................................................................................ 35 6.4 Protected areas ........................................................................................................................................ 36 6.4.1 National protected areas .................................................................................................................... 36 6.4.2 Provincial protected areas .................................................................................................................. 36 6.4.3 Saola Management Area .................................................................................................................... 37 6.4.4 Urbanisation ....................................................................................................................................... 39 7 INFRASTRUCTURE ................................................................................................................................. 39 7.1 Road network and transport .................................................................................................................... 39 7.2 Energy and hydropower ........................................................................................................................... 40


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7.2.1 Hydropower infrastructure ................................................................................................................. 40 8 SOCIAL ECONOMIC PROFILES ................................................................................................................ 43 8.1 Administrative boundaries ....................................................................................................................... 43 8.2 Population ................................................................................................................................................ 44 8.3 Population structure and Ethnicity .......................................................................................................... 44 8.4 Access to public services .......................................................................................................................... 45 8.5 Healthcare ................................................................................................................................................ 46 8.6 Education and Illiteracy ............................................................................................................................ 47 8.7 Water supply and sanitation .................................................................................................................... 48 8.8 Electricity supply ...................................................................................................................................... 49 9 ECONOMIC DEVELOPMENT ................................................................................................................... 49 9.1 Agriculture................................................................................................................................................ 49 9.2 Fisheries ................................................................................................................................................... 50 9.3 Mining, including sand and gravel ........................................................................................................... 51 9.4 Industry .................................................................................................................................................... 52 9.5 Hydropower ............................................................................................................................................. 52 9.6 Tourism .................................................................................................................................................... 52 9.7 Irrigation ................................................................................................................................................... 53 9.8 Transportation ......................................................................................................................................... 54 10 REFERENCES .......................................................................................................................................... 55 11 APPENDIX-A IRRIGATION SCHEMES AND WATER SUPPLY SCHEDULES IN THE CATCHMENT .................. 56


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1 ACK N OW LEDG EMEN TS

The authors would like to thank and acknowledge the assistance of the MK3 project staff, who provided their valuable knowledge and experience as well as advisories, training and support, over more than two years. Their support during field drips and workshop activities enhanced this report’s scientific vision, while MK3 research grants enabled us to conduct this project and to acquire data

We would also like to thank a number of people and institutions for offering data, information and references.

We are grateful to Dr. Kim Geheb Mekong River Leader, Challenge Program on Water and Food, for financial backing and to Peter-John Meynell, Team Leader, MK3 project, who provided a great deal of information about the Nam Theun/Nam Kading expansion and the Nam Theun 2 project report.

We sincerely thank all the district and provincial staff involved in the Nam Theun/Nam Kading, Nam Hinboun and Xe Bang Fai projects, and all villages at the basin rivers, for their invaluable support during the field visits and data collection phases.


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2 I N TROD UC TION This report covers the catchment of the Nam Theun/Nam Kading, Nam Hinboun and Xe Bang Fai Rivers in Lao PDR (thereafter, referred to as the MK3). MK3 is a conservation and livelihoods initiative. It aims to develop and scale out land and water management strategies that increase productivity and reduce land degradation and erosion, thereby slowing the pace of reservoir siltation, while generating benefits to riparian communities. The project addresses the optimisation of dam and reservoir management in cascades of dams for both electricity generation and multiple use of the water upstream and downstream of the dams.

The report is a summary of general aspects covering hydro-meteorological data, physical and biological environment data, socio-economic development activities and potential development on the catchment. Since the data on the Nam Kading is limited, the report mainly focusses on the Nam Theun/Nam Hinboun and Nam Theun1. In Lao, the catchment of the MK3 River mainly covers two provinces, namely Borikhamxay and Khammouane; therefore, the data from the two provinces are extensively used in this report. Data available from existing reports, published literature, maps, statistics, databases, ministries, non-governmental organisations (NGOs) and district level was gathered, compiled and summarised in concise forms.

Some of the main features of the three basins in the MK3 to are presented in Table 1.1. However, for detailed information on each specific section readers are recommended to consult the references provided in the respective section.

Table 1.1: Summary of river basins features

Features Basins

Nam Theun/Nam Kading Nam Hinboun Xe Bang Fai Physical features

Catchment area

14,813 sq. Km (6.25% of national area)



Length 353 Km About 89 Km About 209 Km Elevation Min.: 145 masl (at Kading

River mouth) Max.: 2,288 masl (Phou Lao

Kai, Khamkeut district)

Min.: 138 masl (at Hinboun River mouth)

Max.: over 2,000 masl (at mountains)

Annual rainfall

Min.: 1,739 mm (at Ban Namoew)

Avg.: 2,500 mm Max.: 2,979 mm (Ban Nakai

Tai)

Avg.: 2,646 mm (CS11 station @ Nam Hai_2008-2011)

Avg.: 1,811 mm (CS16 station @ Nam Hinboun_2009-2011)

Avg.: 1,746 mm (CS20 station @ Nam Hinboun_2009-2010)

Avg.: 2,646 mm (at Mahaxai_1989-2002)

Avg.: 2,224 mm (at Gnommalati_1994-2002)

Water resources

Average flow to Mekong River

17,219 x 106 m3/year 16,493 x 106 m3/year

Average discharge

546 m3/second 147.64 m3/second (CS10 station @ Nam Hinboun_2007-2011)

86.49 m3/second (CS11 station @ Nam Hai_2007-2011)

51.13 m3/second (CS10 station @ Nam Hinboun_2008-2011)

523 m3/second

Annual 7,641.03 x 106 m3/year:


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water use agriculture 146.226 mcm %1.948, domestic 78% mcm% 0.102, industrial 4 mcm% 0.001, hydropower 7,700 mcm% p7.98

Land cover and land use (compiled from Y2002 GIS data obtained from NGS)

Natural forest

57.48%

Agricultural land

2.31%

Grassland 0.55% Water surface

0.55%

Urban area 0.02% Other 35.85%

Administration Province included in the Basin

Xiengkhouang, Borikhamxay, Khammouane

Khammouane Khammouane, Savannakhet

Number of districts

9 2 13

Administration Population 142,466 persons (2005) 34,148 persons (only Hinboun

district in March 2011) 231,000 persons (2005)

3 BOU N DA RIES OF TH E BA S IN This profile covers the whole catchment of the three major rivers in Lao PDR, namely the Nam Theun/ Nam Kading, Nam Hinboun and Xe Bang Fai and their tributaries. Sharing catchment borders, these three rivers are situated in the southern part of the central region of Lao PDR. They cover large parts of two provinces, namely Borikhamxay and Khammouane, and also small parts of Mok Mai district in Xiengkhouang province and Xaybouly district, Atsaphone district, Sepone district and Vilabouly district in Savannakhet province. The Hinboun River is situated in the middle and the Nam Theun/ Nam Kading are situated in the northward part of the catchment. The boundary of this catchment is illustrated in Figures 2.1 to 2.4 below.


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Figure 2-1: Boundary of the Catchment for Nam Theun/Nam Kading Basin with existing reservoirs in basin

Figure 2-2: Boundary of the Catchment for Nam Hinboun Basin


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Figure 2-3: Boundary of the Catchment for Xe Bang Fai Basin

Figure 2-4: Three Boundaries of the Catchments for Nam Theun/Nam Kading, Nam Hinboun and Xe

Bang Fai Basins with existing reservoirs in basins


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3 . 1 N A M T H E U N / N A M K A D I N G Nam Theun and Nam Kading are actually parts of same river system and a major tributary of the Mekong, however they are generally separately named. The part upstream from the Nam Gnouang confluence is known as the Nam Theun but the downstream part, from the above confluent point to its confluent point with the Mekong at Pakkading district in Borikhamxay province, is known as Nam Kading. It has several tributaries, namely Nam San, Nam Mouan, Nam Gnouang, Nam Pao, Nam One and Nam Noi. The river system flows through southeast to northwest. Its catchment is mainly situated in Borikhamxay and Khammouane province. Nam San tributary is located in Pakkading and Bolikhan districts in Borikhamxay province; Nam Mouan is located in Viengthong district and at Mok Mai districts in Xiengkhouang province; Nam Gnouang and Nam Pao tributaries are located in Khamkeut district in Borikhamxay province; and others tributaries are located in Khammouane province.

3 . 2 N A M H I N B O U N The Nam Hinboun is the shortest river of the three rivers in the catchment; it is situated in the Hinboun district in Khammouane province and this is also where its confluence with the Mekong is located.

3 . 3 X E B A N G F A I A major tributary of the Mekong, the Xe Bang Fai is is fed by two tributaries, namely Se Noy and Nam Ou La. TheXe Bang Fai flows from its origination at the Lao-Vietnam border at Bualapha district, westward to the Mekong at the border of Xe Bang Fai and Nongbok districts in Khammouane province. The catchment of Xe Bang Fai covers several districts in Khammuane province, namely Nongbok, Xebangfai, Mahaxay, Gnommalath, Xaybuathong and Bualapha, and covers small parts of a few districts in Savannakhet in the south, namely Xaybuly, Atsaphone and Vilabuly.

The total area of the catchment and total area of the districts are shown in Table 2.1. However, only nine districts are significantly impacted by development activities in the region. Therefore; this report focusses on those nine districts, as shown in the Table 2.1.

Table 2.1: The catchment area

No. Province name District name Total area (ha) Area in the basin (ha)

1 Xiengkhouang Mokmai 207,314 72,329

2 Borikhamxay Borikhan 190,618 11,852

3 Khamkeut 438,648 434,902

4 Pakkading 239,312 139,982

5 Pakxanh 173,875 12,552

6 Thaphabath 75,500 5,723

7 Viengthong 449,931 444,028

8 Khammouane Bualapha 324,487 296,068

9 Hinboun 298,511 243,629

10 Mahaxay 140,265 138,967

11 Nakai 433,272 433,271

12 Gnommalat 157,201 155,090

13 Nongbok 133,587 26,970

14 Thakhek 97,435 17,666

15 Xaybouathong 88,566 88,566

16 Xebangfay 194,183 93,574

17 Savanakhet Atsaphone 145,178 35,105


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18 Sepone 226,388 5,412

19 Vilabuly 176,467 58,671

20 Xaybuly 89,177 60,075

Total 4,279,915 2,774,433

Source: Field survey from October 2010 to March 2011.

4 P HYSICA L CHA RAC TERIST ICS 4 . 1 T O P O G R A P H Y A N D G E O L O G Y

The headwaters of the Nam Theun and Nam Gnouang are located in the Annamite mountain chain which forms the border between Lao PDR and Vietnam. The highest mountains in this chain rise over 2,000 m above sea level. The headwaters of Nam Hinboun are located west of the Nam Theun catchment at about 400 masl. At the confluence with the Nam Kading, the Mekong River is located at an elevation of about 140 masl and at the confluence with the Nam Hinboun is 138 masl.

Absolute elevations of the catchment range between about 140 m on the Mekong Flood Plain to about 2,300 m along the Annamite watershed. Many mountains in the watershed, and isolated mountains within the catchments, have summit elevations of 1500 m to 1900 m. The most notable features of the relief are the scarcity of flat land (Figure 3.1). There are high average slope values and long cliffs and escarpments of 200m to 500 m height along the WNW-ESE alignments of the sedimentary systems, marking the boundaries of different sedimentary rock types.


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(Light green: Agricultural land and grassland; Darker blue-green: Barren rock; Red-brown: Wooded) Figure 3-1: Landsat image of parts of the project area general geology


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The geology of the region covering the project area is shown in Figure 3.2.

Figure 3-2: Geology of the area Source: Geological Map of Cambodia, Lao PDR and Vietnam

4.1.1 Nam Theun/Nam Kading The Nam Theun/Nam Kading catchment is geologically diverse, with rocks of alluvial, sedimentary and igneous origin. A corridor of red conglomerated sandstone, siltstone and clay stone run on each side of the Nam Theun/Nam Kading main stream channel from the source to the confluence with the Mekong. Parallel to this, to the north and south, are Carboniferous and Devonian pavement and karsts limestone uplands, with isolated granite extrusions.1 .

4.1.2 Nam Hinboun The Nam Hinboun catchment lies predominantly in the limestone zone, coming off the extremely steep Nakai-Nam Theun Plateau, descending through limestone uplands and down through quaternary alluvial sandstone, siltstone and clay stone of the Mekong main stream floodplain.2 .

4.1.3 Nam Gnouang Reservoir and Dam site The NG Reservoir area consists of Jurassic sandstone and Carboniferous karstic limestone. The majority of the limestone is found bordering the southern shores of the reservoir. The reservoir water is in most

1 Source: NORPLAN, 2008. 2 Source: NORPLAN, 2008


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areas separated from contact with the limestone by an underlying layer of relatively impervious siltstone rock overlain by deeply weathered impervious residual material. The NG Dam site is located at a point where the Nam Gnouang breaks through a ridge of Carboniferous limestone, schist, shale and siltstone, which includes karstic limestone of the Bacson series, to enter younger Jurassic-Cretaceous sandstones, conglomerates and siltstones. The dam site is located over impermeable Jurassic sandstones.3 .

4 . 2 S O I L In general, hill soils are shallow, acidic and strongly leached. Silts and fine sands are chiefly found on slopes. Finer particles are accumulated on valley floors and here deeper clay-dominated soils have developed. The Nam Hinboun catchment is dominated by Acrisol and Cambisol (Figure 3.3) in addition to large areas covered barren with calcareous rock.4.

Figure 3-3: Soil types in the Nam Hinboun catchment Source: Chareun 2007.

4 . 3 S E I S M I C I T Y The seismic earthquake conditions have been studied in the Nam Theun catchments in connection with the different plans for hydro-power dam construction. The studies indicate that the maximum horizontal surface acceleration for a maximum credible earthquake would be in the range of about 0.1 to 0.12 g

3

Source: NORPLAN, 2008 4

Source: NORPLAN, 2008


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(SWECO 2006). A well designed and constructed RCC dam type does not require any special construction measures to withstand this value of seismic shaking.5.

4 . 4 C L I M A T E The profiled topography of the catchment determines the patterns of air temperatures and rainfall resulting in large differences in temperature and rainfall frequency and intensity.6 .

4.4.1 Temperature Air temperatures are measured on a daily basis by the THPC Environment Monitoring Division (EMD) at the headpond and at the power house at Ban Khounkham. The calculated average monthly air temperatures at the headpond site and at the powerhouse are based on the EMD measurements from 1999 to 2006. Average minimum monthly air temperatures range from 16.0 Ċ – 36.3 Ċ7.

4.4.2 Rainfall The local rainfall of the Nam Theun Basin is very complex and significant efforts have been made to understand the rainfall pattern in the project area. The catchment’s northeast boundary comprises the divide between the rivers emptying into the South China Sea and the rivers emptying into the Mekong. The rainfall on each side of this divide is dominated by different weather systems. During the southwest monsoon the winds bring humid air from the Indian Ocean causing the wet season to peak in July-August in Lao PDR. In central Vietnam, however, much rain falls in the transition period between the southwest and the northeast monsoons (which carry humid air from the South China Sea) giving a peak rainy season in September and October. It was found that the heavy rain falls in Vietnam during these months also spill over to the upper mountainous part of the Nam Theun Basins in Lao PDR. The rainfall in the Nam Theun Basin is therefore a mix of both the southwestern and eastern water systems8.

To add to this complex situation, the mountains along the border between Lao PDR and Vietnam affect the local climate. The steep slopes and mountains ridges cause rainfall due to orographic effects on one side, but create a rain shadow on the other side. Besides giving very large local variations this phenomenon causes a dip in average annual rainfall along the centre of the Nam Theun Basin. Annual rainfall is higher at the water divides because of orthographic effects during either the southwest or the northeast monsoon, while the central parts suffer from the rain shadow. This effect is especially prevalent in the Nam Phao and Nam Gnouang tributaries, which receive the least amount of rainfall within the Nam Theun Basin. The complex rainfall pattern is illustrated in Figure 3.4.

5 Source: NORPLAN, 2008 6 Source: NORPLAN, 2008 7 Source: NORPLAN, 2008 8 Source: NORPLAN, 2008


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Figure 3-4: Isohyet map of the project area Source: SWECO, 2006. Of major importance is also the fact that the Nam Theun Basin is regularly affected by typhoons. The river basin is located in the direct path that typhoons normally take during the months of September and October. The typhoons may cause extreme rainfall and runoff and historic records show that large floods in the Nam Theun are often related to such events. Typhoons must therefore be taken into account for estimation of floods in the Nam Gnouang, Nam Phao and Nam Theun Rivers.

Annual rain fall for the NT2 project measured at Nakai Tai in 2010 was about 2,210 mm/year (NTPC, 2011). However, the average value of two stations, Vientiane and Savannakhet, from 1995 to 2006 measured by the Department of Meteorology and Hydrology was about 1680 mm/year (National Statistics Center, 2006).

4.4.3 Evaporation The NT2 project has established a pan type evaporation measuring system, located at Ban Nakai Tai, for daily time series basis. The average evaporation value in the period 2006 to 2010 was 1,635 mm/year.

However, for the Nam Hinboun catchment, it is believed that evaporation is relatively similar to the values in Thailand (1,084 mm/year at Ban Phaeng and 1,000 mm/year at Nakhonphanom) and is less than 1,000 mm/year.9.

4 . 5 H Y D R O L O G Y Two major river systems will be impacted by the planned project: the Nam Theun/Nam Kading catchment (which also includes Nam Gnouang) and the Nam Hinboun/Nam Hai catchment. The outline of the catchments can be seen in Figure 3.5 below.

9 Source: NORPLAN, 2008


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Figure 3-5: Relevant catchments and sub-catchments Source: NTPC, 2005. EIA report of Nam Theun 2.

The natural Nam Theun/Nam Kading catchment covers a total area of 14,813 sq.km (59%) and is upstream of the present Theun Hinboun Weir. In relation to the existing THPP and the planned expansion this catchment can be considered as the “upstream river catchment”. Below the THPP weir the river system has been modified by the THPP diversion of flow into the Nam Hinboun/Nam Hai Basins. This has significantly reduced the dry season flow downstream in the Nam Kading. Further reduction in the downstream flow will result from the implementation of THXP. Effective from 2008, the runoff from about a half of the Nam Theun catchment will be diverted into Xe Bang Fai from the Nam Theun 2 Reservoir on the Nakai Plateau. Only a 2 m/s compensation flow will be discharged from the dam except for possible reservoir overspill in extreme flood situations.

SWECO (2006) has modelled the inflow of the two catchments, using the latest data on rainfall and taking into account evaporation and rainfall on the planned reservoir and the headpond. The results are seen in the table and the duration curves below.


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Figure 3-6: Reservoir inflow duration curve Source: SWECO, 2006

Figure 3-7: Headpond inflow duration curve Source: SWECO, 2006.

4.5.1 Nam Hinboun/Nam Hai The Nam Hai catchment receives extreme rainfall. The annual average is about 4000 mm and maximum intensities of 260 mm/day and 115 mm/hour have been observed. The Nam Hai thus experiences rapid fluctuations in water levels and flows. The flood peaks are high and normally have short duration. The Nam Hinboun shows slower response; the catchment is much larger and the extensive limestone areas that provide good infiltration capacity buffer the rainfall events. The Nam Hinboun, therefore, shows a distinct seasonality in flows with high flows during most of the rainy season and significant base flows throughout


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the dry season.10 .

Figure 3-8: Flow duration curve at Nam Hai before its confluence with Nam Hinboun with and without the THPP operation (SWECO 2007)

Figure 3-9: Flow duration curve of Nam Hinboun at Ban Khen with and without the THPP operation

(SWECO, 2007)

Figure 3.8 shows the comparison of flow durations in natural conditions and with the present releases from THPP. The effects of the power plant operational regime are significant in the Nam Hai. Dry river conditions, which were occurring about 40-45 % of the time, now only occur 1-2% of the time, while the duration of flows above 110 m/s has increased from 3% to 50% of the time. In the Nam Hinboun at Ban Khen (just upstream of the narrow gorge through the mountain ridge) the effects of the THPP releases are significantly less than in the Nam Hai (Figure 3.9). Here, the natural flows of more than 110 m/s occurred 30% of the time and activities around the river were thus probably accustomed to these high levels during the rainy season. With the THPP operation the flows above 110 m/s now occur 58% of the time. A significant change from the normal situation, however, is that also at Ban Khen the levels of mean annual low flow (2.7 m/s) have become very rare due to THPP operations.

The results of the hydrological assessment further indicate that the strongest impact of THPP operation peak flows are found in the Nam Hai. The peak flow is the hydrological parameter which is

10 Source: NORPLAN, 2008


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most important for judging impacts on the river morphology. Here, the mean annual flood is presently increased by 30-50% compared with natural conditions, while the 100-year peak is increased by about 15-25%. In the Nam Hinboun, the effects of THPP releases are considerably lower. The mean annual flood is today only increased by some 10% and the 100-year flood by some 5%.

4 . 6 R I V E R G E O M O R P H O L O G Y A N D D R A I N A G E N E T W O R K The Nam Gnouang Reservoir (NG Reservoir)/Nam Theun-Hinboun expansion (THXP) project had created a maximum 105 and minimum 15 square kilometre reservoir area on the Nam Gnouang about one kilometre upstream of Ban Thasala and 27 km upstream of the existing THPP diversion weir. Water from the THPP diversion weir will be diverted by an intake structure, located about 5.5 km upstream from the weir (THPP), into a diversion tunnel excavated downstream to join the Nam Hai . The water discharged from the powerhouse will then flow through a purpose-built 3 kilometre downstream channel to join the Nam Hai and continued to join the another river system, like the Nam Hinboun, which also flows into the Mekong River, but about 91 km south of the Nam Theun/Nam Kading as presented in Figure 3.9.

Figure 3-9: The schematic of Nam Gnouang Reservoir/Nam Theun and Nam Hinboun The Nam Theun 2 hydropower project has created a 450 square kilometre reservoir on the Nakai. Water from the Nakai Reservoir is diverted by an intake structure, located about 40 km upstream from the dam, into a diversion tunnel excavated in Thu Ark Escarpment. The water in this tunnel will then drop about 350 m before entering the turbines in a powerhouse located at the foot of the escarpment (see Figure 3.10).


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The water discharged from the powerhouse will then flow through a purpose-built 28 kilometre long downstream channel to another river system, the Xe Bang Fai, which also flows into the Mekong River, but about 150 km south of the Nam Theun/Nam Kading.

Figure 3-10: The schematic of Nam Theun 2 and Xe Ban Fai

4 . 7 W A T E R Q U A L I T Y A number of water quality analyses are available for the river systems upstream and downstream of the THPP. Most of these studies have been made as a part of the planning and assessment of hydropower developments. Therefore they have often been ad hoc in character and few long times series of data exist.

For the Theun Hinboun project area, older data series are found in NORPLAN (1995). The NORPLAN analysis covers December 1994 and March, April and July 1995.

The water quality parameters measured by Environmental Management Division (EMD) have been: temperature, dissolved oxygen (DO), oxygen saturation (DO %), pH, total dissolved solids (TDS), total hardness, conductivity, salinity, suspended solids (SS), turbidity (NTU), Secchi disk reading, ammonia (NH-N), total phosphate (Tot-P), chemical oxygen demand (COD), faecal coliform bacteria and total coliform bacteria. The data are available in a database format but have not always been consistent.

It is important to recognise that there are dramatic seasonal and yearly fluctuations in water discharges in the Nam Theun, Nam Gnouang, Nam Hai and Nam Hinboun. Several of the water quality parameters are functions of flow. Some pollutants will be diluted at high flows but heavy rains and resulting high floods might cause flushing and mobilising of pollutants and sediments.

4.7.1 Sub Basin Characteristics Below is a brief summary of some of the features of the relevant sub-catchments influenced by the project. The presentations in Table 3.1 to Table 3.2 are based on a synthesis of the data from the EMD monitoring from 1998 to 2006, supplemented with some information from other sources (i.e. RMR, 2006 and Schouten et al. 2004). In addition to the general status of the river reaches described below, a more detailed discussion of the priority issues turbidity and oxygen is provided in separate sections. The figures in the summary tables show that the reaches studied in most cases have satisfactory levels of most of the parameters measured. Except for the diversion of water from Nam Theun into the Nam Hinboun catchment and the erosion induced by swidden agriculture practices and the water diversion, impacts on water quality from human activities are very modest. It is striking to see the great variation in the maximum and minimum readings of most parameters. This reflects the dramatic


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changes in water quality over the year caused by very high variations in wet season and dry season river flow. Seen in light of the large variation between the maximum values and the minimum values, the differences between river reaches are minor. It is probable that some of the more systematic chemical differences between the rivers seem negligible compare to the seasonal variation and the extreme maximum and minimum values.

1) Nam Gnouang

The water quality in the Nam Gnouang is generally high; it has neutral pH, low conductivity, no salinity, low values of nutrients and no measurements showing significant levels of organic micro pollutants, heavy metals or coliform bacteria. The Nam Gnouang has at times experienced extremely low water temperatures. In January 1975, when air temperatures dropped below 0 Celsius at night, a massive fish kill affecting numerous fish species was observed because of the resulting low water temperature. Heavy rainfall in the upstream reaches sometimes causes landslides which contribute to high concentration of suspended solids (SS). The very high maximum values for SS can be attributed to such events. Table 3.1: Summary of 1998-2006 water quality data from Nam Gnouang Dam site (EMD 2A)

Parameter Maximum Average Minimum Temperature (oC) 32.3 24.8 16.7 Dissolved Oxygen (DO mg/l) 9.9 7.4 4.5 Total Dissolved Solids (TDS mg/l) 131.0 52.8 27.0 Total Hardness (mg/l) 135.0 45.4 5.0 Suspended Solids (SS mg/l) 685.0 56.2 5.0 Nitrogen (NO3- N mg/l) 2.70 0.41 0.10 Phosphorous (Tot-P mg/l) 0.46 0.09 0.01

2) Nam Theun and upper tributaries Water quality in the Nam Theun, in particular in the upper reaches which will be diverted into Xe Bang Fai by the NT2 project, is uniformly high, with neutral pH, low conductivity, no salinity, low values of nutrients and negligible pollutants. The sediment transport is low in the dry season since the larger part of the upper catchment is inside the NPA. Even in this relatively “unpolluted” river, the measured minimum values for dissolved oxygen are very low (below the Thai standards for fisheries). This happens in the wet season when transport of organic materials is high and light penetration in water bodies low. Table 3.2: Summary of 1998-2006 water quality data from Nam Theun upstream headpond (EMD 1A)

Parameter Maximum Average Minimum Temperature (Ċ) 32.3 24.8 16.7 Dissolved Oxygen (DO mg/l) 9.9 7.4 4.5 Total Dissolved Solids (TDS mg/l) 131.0 52.8 27.0 Total Hardness (mg/l) 135.0 45.4 5.0 Suspended Solids (SS mg/l) 685.0 56.2 5.0 Nitrogen (NO3- N mg/l) 2.70 0.41 0.10 Phosphorous (Tot-P mg/l) 0.46 0.09 0.01

3) Nam Kading The quality values of the water in the riparian release and flood season downstream in the Nam Kading show many similarities with the upstream river reaches. One notable point from the monitoring data is the very high maximum figures for dissolved solids and suspended solids. The most likely explanation for this situation is that the riparian flow releases are drawn from a sediment rich deep layer in the headpond. Furthermore, low minimum values of dissolved oxygen have been found, but it is assumed that the oxygen is quickly replenished in the river rapids in the upper Nam Kading.


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Table 3.3: Summary of 1998-2006 water quality data from Nam Kading below headpond (EMD 3)

Parameter Maximum Average Minimum Temperature (oC) 31.5 24.8 17.6 Dissolved Oxygen (DO mg/l) 11.9 7.5 4.4 Total Dissolved Solids (TDS mg/l) 261.0 34.2 13.3 Total Hardness (mg/l) 90.0 28.2 12.0 Suspended Solids (SS mg/l) 327.0 38.3 3.0 Nitrogen (NO3- N mg/l) 1.60 0.32 < 0.05 Phosphorous (Tot-P mg/l) 0.39 0.06 < 0.005

4) Nam Hai and Nam Hinboun

The Nam Hai and Nam Hinboun water flow and water quality has undergone significant changes since 1998 when the THPP commenced operation. From being rivers with large seasonal variations in flow and quality (as seen in the upper reaches of the rivers today), there is a high year-round flow but with very large daily fluctuation. The dramatic increase in dry season flow and the intermittent discharge, varying from 0 to 110 m/s in one day, have started extensive erosion processes, in particular along the Nam Hai. This process is still ongoing and river morphology does not yet seem to have been stabilised. Table 3.4: Summary of 1998-2006 water quality data from the Nam Hai and Nam Hinboun impacted by the present power plant (EMD 8 and 11)

Parameter Maximum Average Minimum Temperature (oC) 32.1 25.0 13.4 Dissolved Oxygen (DO mg/l) 11.9 7.7 3.5 Total Dissolved Solids (TDS mg/l) 145.2 48.0 16.0 Total Hardness (mg/l) 162.0 46.7 13.5 Suspended Solids (SS mg/l) 230.0 64.3 18.0 Nitrogen (NO3- N mg/l) 2.60 0.46 < 0.05 Phosphorous (Tot-P mg/l) .00 0.10 0.01

4.7.2 Heavy metals A particular water quality problem is encountered in the lower part of the Nam Hinboun. In the Nam Pathaen tributary of the Nam Hinboun there are mines producing heavy metals like tin, lead and zinc. There is presently high activity at the mines and this contributes significantly to pollution problems in the Nam Pathaen and subsequently in the lower Nam Hinboun.

High levels of turbidity can also be observed. Regular monitoring is not carried out but one sample taken in Nam Phaeten in July 1995 showed high levels of several heavy metals including lead, zinc, tin and cadmium. The content of iron was extreme (18,700 µg/l compared to the WHO and Lao PDR standard of 300 µg/). In the same period the iron concentration in the lower Nam Hinboun also exceeded the water quality standards (NORPLAN, 1997). There is a concern that the mining activity might be causing high concentrations of heavy metals in fish and other aquatic organisms.

4.7.3 Oxygen Status The oxygen content of water bodies is important for the ecological status of the water. Oxidation of organic (and other reactive) materials in the water and on the bottom of rivers and reservoirs will consume dissolved oxygen. The replenishment of oxygen takes place by aquatic plant photosynthesis, thermal turnover, diffusion from the surface, water and air mixing in streams and rapids and by wind action in lakes and reservoirs.


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If the water is stagnant, or if the input of organic material is too high, the concentration of oxygen in the water column will be diminished and in some cases reach zero (anoxic conditions) in the deeper stagnant layers.

4.7.4 Stratification In lakes and reservoirs under stable conditions, stratification in temperature and oxygen concentration might develop. In Lao PDR this happens in the dry season when the inflow is low. The reservoir develops a cooler bottom layer depleted of oxygen (hypolimnon) and an upper warmer layer (epilimnon) where oxygen is replenished by diffusion, plant photosynthesis and mixing. Adding to the problem of stratification is the fact that plants produced in the epilimnon will die and sink down to the hypolimnon and thus provide more organic material to be digested. Unless the reservoir is deep, the inflow of large quantities of water in the wet season will cause a turnover of the whole water column and thus bring oxygen to the deep layers of the reservoir.

Biodiversity comes under stress when the oxygen content in the water is reduced. Some species are more sensitive to the reduction than others and the species composition might change. Under anoxic conditions the ecological situation changes completely and the oxidation process shifts into other chemical pathways and produces, for instance, H2S, ammonia and methane, which are toxic to most organisms. Anoxic situations will instantly lead to death of all fish species and other higher animal organisms. When, however, the water is again exposed to oxygen the chemical process is rapidly reversed and the organisms might re-establish themselves.

A common cause of oxygen depletion is pollution from domestic or industrial waste water with high organic content (food processing, paper mills, etc.).

The oxygen monitoring data in the catchment area is measured by level of dissolved oxygen (DO). No specific Lao PDR water quality standards exist for oxygen status. However, in Thailand the standard requirement of surface water suitable for conservation of aquatic organisms and fisheries is set at DO 6 mg/l occurring for at least 20% of measurements.

The Nam Theun, Nam Gnouang and most of the upstream tributaries in the catchment area are rapid flowing (good oxygen mixing) and have relatively low traces of organic material. Therefore the dissolved oxygen status at most of the stations are characterised as high (6-8 mg/l) or very high (> 8 mg/l).

At the Environmental Management Division monitoring stations of the Nam Theun and Nam Gnouang (both stations located in slow flowing water close to the THPP headpond), dissolved oxygen levels typically fall to between 4 and 5 mg/l in September and October (Figure 3.3). During these months rainfall and run off are very high. This brings detritus and organic material from the land into rivers and streams causing a decline of DO in the Nam Theun and Nam Gnouang. However, no DO concentrations lower than 4.5 mg/l have been measured during the rainy season.

5 BIOLOG ICA L EN VIRONMEN T 5 . 1 T E R R E S T R I A L H A B I T A T S , L A N D U S E A N D V E G E T A T I O N C O V E R

The Nam Gnouang catchment is situated in the Annam Biogeographic Sub Unit (5B). The catchment is a mosaic of habitats and forest types. The entire area is crisscrossed by small rivers and streams and features impressive limestone outcrops rising to 1600 masl and covered in mostly deciduous species. These outcrops contain many caves that are suitable for cave dwelling wildlife such as bats, birds and small mammals.

5.1.1 Nam Gnouang catchment A large percentage of the area is covered with agricultural land and vegetation heavily modified by human activities. However, the upper reaches of both the Pon and Khamang tributaries contain what appear to be good quality forests. This is most likely due to the large distance these areas are from villages along with their inaccessibility.


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In areas of original forest cover, mixed deciduous forest is the most prominent (Figure 4.1A). This forest type is located along streams and on hillsides. Patches of evergreen forest persist in gullies at higher elevations and there are stands of deciduous and bamboo forest.

Figure 4-1: Different habitats along the Nam Pon. A. Mixed deciduous forest. B. Evergreen forest.

C. Deciduous forest. D. Bamboo forest.

Areas close to villages located along the Nam Gnouang could be regarded as unstocked forest or upland field re-growth. These are previously forested areas where crown density has been reduced to less than 20% (or in some cases 0%) due to disturbance from shifting cultivation practices. These agricultural practices have led to a loss of forest structure, species diversity and the ecological processes that characterise natural forests. Areas currently being used for upland agricultural practices are virtually devoid of vegetation aside from whatever crop is planted there.

Upland shifting agriculture has been practiced for many years in the area and due to varying fallow periods (3-10 years) the disturbed landscape is a mixture of re-growth stages. Areas in fallow for 1-3 years are dominated by grasses and herbaceous perennial plants such as Imperata cylindrica, Themeda triandra, Eupatorium odoratum, Ageratum conyzoides and Erianthus arundinaceus. In areas

C

D


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that have been fallow for approximately 3-6 years it is evident that pioneer tree species have begun to regenerate and previously dominant grasses and herbaceous plants have declined. In areas that have been fallow for 8-10 years trees have started to form an open canopy, although bamboo species are prominent.

5 . 2 W I L D L I F E

5.2.1 Regional Status Most of the attention of conservationists in the last decade has been directed at the biodiversity of the Nakai Plateau area, which is beyond the impact zones of this project. The most relevant studies covering the relevant impact zone were commissioned in 1995 from the Wildlife Conservation Society (WCS) in connection with the initial THPP. The study concluded that at least 5 globally threatened birds and 12 globally threatened mammals lived within the area affected by the original Theun Hinboun Project. In addition, 22 other important species were found to have populations in the affected area. A number of habitats were identified as being vulnerable to damage or destruction by the project. The definition of the impact area also includes the Nam Kading National Protected Area which is located on each side of the Nam Kading downstream the THPP headpond.

The animals listed by the WCS as at risk of experiencing significant impairment from the project’s impact events are shown in Table 4.1 below:

Table 4.1: Animals at risk of significant impairment by Theun-Hinboun Project (WCS 1995)

Species Status Oriental Darter Globally Near-Threatened Lesser Fish Eagle Globally Near-Threatened River Lapwing National Long-term Decline Long Billed Plover Globally Near-Threatened Small Pratincole Regionally At Risk Pale-Capped Pigeon Globally Threatened Crested Kingfisher Regionally At Risk Blythe’s Kingfisher Globally Threatened Red-Collared Woodpecker Globally Threatened Wire-Tailed Swallow Regionally At Risk Rufous-Throated Fulvetta Globally Near-Threatened Rhesus Macaque Regionally At Risk Dhole Globally Threatened Large otters (2 spp.) Regionally At Risk Asian Small-Clawed Otter Globally Threatened Asian Elephant Globally Threatened Gaur Globally Threatened

A further 38 species of birds and mammals were listed as being at risk of experiencing a slight impairment. Dominant in the list of mammals and birds that were suspected to be negatively impacted were water-related species which might be impacted by the reduced water flow in the Nam Kading.

A significant reduction in the occurrence of some species in and around Nam Kading NPA has been observed. How much of this reduction can be attributed to the THPP and how much is caused by other developments, for instance increased hunting pressure, has not been established.

The WCS study recommended certain mitigation and compensatory measures to reduce the impact on wildlife. Most of the mitigation measures recommended by WCS were not effectively adopted and there has been no follow-up survey to determine the impact of extent of damage to the animal populations at risk. Some of the initial management actions have recently been proposed to be included in the Environment Management and Mitigation Plan for the NT1 Hydropower Project.


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5.2.2 Nam Gnouang catchment The Nam Gnouang Reservoir and catchment area contains a great diversity of wildlife species. Numerous surveys have been conducted in surrounding areas by various teams. A summary of recent observations of birds and mammals species is given in Table 4.2. The list is compiled from direct observations and interviews with informants from villages during the field visits. The table is limited to "key species" of conservation concern, as defined by Duckworth et al. (1999). As the information was gathered opportunistically it cannot be regarded as a comprehensive list of key species in the area.

Table 4.2: Comments on key wildlife species in the upper Nam Gnouang catchment. Based on Robichaud, 2005 and WCS 2007

Species Status Birds

Crested Argus (Rheinardiaocellata) Reported present (but less common than formerly) in the vicinity of Ban Sopchat.

Bar-backed Partridge (Arborophila brunneopectus)

One caged bird seen in Ban Phonekham.

Crested Kingfisher (Megaceryle lugubris) Just one was seen along the Nam Gnouang. Although Tizard (1996) reported 4-5 pairs on the Nam Gnouang and Nam Heung.

Great Hornbill (Buceros bicornis) Casques of Great Hornbill (one each) were seen in Ban Sensi, Ban Phonekham and Ban Sopchat. Villagers said the species still occurs in the general area.

River Lapwing (Vanellus duvaucelii) Just one pair was observed during the survey, on the Nam Gnouang, within 2 km upstream of Ban Sensi. Tizard (1996) reported 8 pairs on the same stretch of the Nam Gnouang.

Large-billed Crow (Corvus macrorhynchos) A maximum of 2 were seen one-way along the Nam Gnouang and 3-4 along the Nam Heung.

Mammals Macaques Residents of Ban Phonekham reported that three species

inhabit the area; the description of one fits Rhesus Macaque (Macaca mulatta). In Ban Phonekham, a freshly butchered primate carcass was seen and villagers' description of the live animal corresponds to Bear Macaque (Macaca arctoides).

Douc Langur (Pygathrix namaeus)

Reported to be very common locally by residents of Ban Sopchat.

Phayre's Langur (Semnopithecus phayrei)

A grey monkey (called "chang" in Khmu) that most likely equates to Phayre's Langur was reported present locally by residents of Ban Phonekham.

Gibbons All villagers questioned reported gibbons present in the area. Bears Two species reportedly present, fitting Asiatic Black Bear

(Ursus thibetanus) and Sun Bear (Ursus malaynus). Otters Two species ("bouan" and "nak") reportedly still inhabit both

the Nam Gnouang and Nam Heung, but apparently less commonly than before.

Asian Golden Cat (Catopuma temminckii A juvenile golden cat was seen captured by a villager in the upper reaches of the Nam Khamang

Tiger (Panthera tigris) Tiger may survive at very low density in the area. Ban Kuang villagers believe one might still inhabit the upper Houay Kao on the east side of the Nam Heung, north of the village.

Asian Elephant (Elephas maximus) None occur in the area, and have not for a very long time – at least 20-30 years.

Heude’s Pig (Sus bucculentus) Villagers consistently reported that two species of pigs inhabit the area, and that both are common and crop pests. Presumably, Eurasian Wild Pig (Sus scrofa) and the Indochinese endemic, S. bucculentus.

Saola (Pseudoryx nghetinhensis) This species is extremely rare and known to occur in the area relevant to the NG.


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Muntjac Villagers collectively reported three species of Muntjacs in the general area, the descriptions of which apparently correspond to Large-antlered Muntjac (Muntiacus vuquangensis), Red Muntjac (M. muntjak), and Truongson Muntjac (M. truongsonensis).

Sambar (Cervus unicolor) Antlers (one set each) were seen in Ban Sensi and Ban Sopchat. Villages variously reported one (Ban Sensi) or two (Ban Koang and Ban Sopchat) species of “khouang” present.

Gaur (Bos gaurus) Probably absent from the area of Ban Sensi. Elsewhere, vague but conflicting information was given.

Banteng (Bos javanicus) More than one village reported the presence of a remnant herd (numbering fewer than ten individuals) of wild cattle that, based on their descriptions, is probably Banteng, around the upper Nam Kamang.

Serow (Naemorhedus sumatraensis) Generally reported to occur in nearby mountainous, rocky areas.

Black Giant Squirrel (Ratufa icolour)

Two partial tails said to be from, and consistent with, this species were seen in the house of the vice-chief of Ban Sopchat.

Of these species particular focus has been on the extremely rare and endangered Saola (Pseudoryx nghetinhensis) which is endemic to this part of Laos PDR. This animal is regarded as having the highest priority for conservation in the Lao PDR (WCS 1999). The consensus of the villagers interviewed is that Saola may remain in the area, but in very low numbers due to hunting. It seems unlikely that they occur close to Ban Sensi today, although Tizard (1996) mapped a small area of occurrence just east of the village nine years ago. The remaining Saola are probably found further up the Nam Gnouang/Heung/Chat basin.

Fauna also includes the Laotian rock rat or khanyou (Laonastes aenigmamus), sometimes called the "rat-squirrel" which is found in the inaccessible limestone mountains of Pha Kouanchan Provincial Protected Area. This large rodent belongs to the ancient fossil family Diatomyidae, and was first scientifically described in 2005.

The following key species were reported to have disappeared from the area: Green Peafowl (Pavo muticus), Golden Jackal (Canis aureus), Dhole (Cuon alpinus), Asian Tapir (Tapirus indicus) and rhino. The only surprise amongst this list of absentees is Dhole; it apparently occurred formerly but few or none survive in the area today.

5.2.3 Nam Hai and Nam Hinboun Catchment The Phou Hin Poun NPA which covers a substantial part of the catchment and transmission line corridor was declared an NPA (NBCA) in 1993 (PM Decree 164). The NPA is reported to harbour over 20 species of mammals including Asian Elephant, Gaur, Sam- bar, Bear, several big cat species, etc. It also contains a significant number of vulnerable bird species, 81 species of reptiles, and 47 species of amphibians.

5 . 3 A Q U A T I C E C O L O G Y

5.3.1 River Ecology The main rivers and tributaries in the project impact zones offer a variety of ecological conditions, which again determines the aquatic fauna and flora. The most important features are the river profiles and morphology and the seasonal fluctuations in river discharges, water levels and water quality.

1) Habitats

The most important habitats for fish and other aquatic organisms’ biodiversity are as follows:

• Floodplains are found on level land where the river overflows large areas of land in the wet season. The most significant floodplain areas are found on lowland rivers such as the Nam


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Hinboun and the lower part of the Nam Kading. In these rivers, floods in the Mekong will give backwater effects and cause flooding of low-lying surrounding land up-stream of the confluence. The organic materials found in these flooded areas create spawning and breeding grounds for many fish species and give rise to fisheries both in the flooded fields and in the rivers when water resides. Several fish species found in the main Mekong migrate to spawn in the tributary floodplains in the wet season.

• Deep pools are features found in both slow flowing reaches and in reaches with rapids. Such pools serve as dry season refuge areas and spawning grounds for many fish species and are the most important fishing sites in both the Nam Theun/Nam Kading and Nam Hinboun river systems. Deep pools are formed by scouring just upstream and just downstream of rapids. An important pool area is found downstream of the Keng Vang Fong rapids on the Nam Kading, 38 km upstream of the Mekong confluence (at the dam site of the planned NT1 hydropower project). An agreement has been reached to protect this pool area as a fish conservation zone. Deep pools are also found in slow flowing river reaches in the Nam Gnouang, Nam Hinboun and lower Nam Kading. On sandy substrate bottoms these pools might change in form and depth by the process of erosion and sediment transport. The intermittent flow release from THPP has significantly reduced the number of pools in the downstream part of Nam Hinboun.

• Rapids form habitats with ecological conditions very different from those found in the main river reaches and provide feeding and spawning grounds for species particularly adapted to such conditions. The often rocky substrate and high currents also give good conditions for benthic plant growth and invertebrates that are a source of food for some fish species.

2) Flow fluctuations

In addition to the different morphological features, the ecological conditions for fish and other aquatic organisms are very much determined by seasonal and daily water level fluctuations. Data series from the period before the THPP was constructed show that the average maximum and minimum water levels differs by as much as 16 m from the dry to the wet season in the Nam Theun/Nam Kading and as much as 12 m in Nam Hinboun. The maximum change in water levels from one day to the next has been measured as high as 9 m in both the Nam Theun/Nam Kading and Nam Hinboun.

Due to seasonal fluctuations of river discharges and water levels, and subsequent changes in water quality, the conditions of aquatic habitats differ seasonally. As a result of dynamic natural changes in aquatic habitats, the species composition of aquatic life, and the abundance of aquatic populations, fish production and fish catch change seasonally and annually as well. Floods can flush out certain fish species from rivers, floodplains can be inadequately flooded affecting fish recruitment and flow, temperature and water quality factors that trigger migration might fail. During some years, aquatic habitats provide the right conditions for spawning but in other years there is little recruitment of particular fish species due to unfavourable conditions of aquatic habitats. In particular, landslides, erosion and subsequent sedimentation affect spawning habitats such as riverbanks, deep pools and rapids. Sedimentation is aggravated by extreme floods and land and water uses by a growing human population. Fish that are abundant one year might be totally absent the next.

3) Migration

Migration between different aquatic habitats has often triggered flow conditions that change concentrations of suspended solids and water transparency. Such factors affect the availability of food for fish and the spawning migrations of fish, both being strongly related to concentrations of suspended solids. Most fish species that migrate upstream in September, when suspended solids are high, are searching for upstream rapid reaches where the water levels have receded and concentrations of suspended solids have declined. At the beginning of the rainy season, when suspended solids increase, spawning migration aims for floodplains where sediments settle or for clean upstream reaches of ephemeral streams.


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5.3.2 Aquatic Biodiversity

1) General The Mekong Basin supports a rich aquatic diversity. The Fisheries Program of the Mekong River Commission estimates that about 1,200 fish species might be found in the Mekong River Basin but only some of these have been identified and scientifically described. Even less is known about the biological and ecological requirements of the fish species. Fish species with geographically limited distribution areas or which are confined to specific rivers (endemic species) are frequently found in the headwaters of many tributaries to the Mekong.. The reasons for this are both isolation though geological processes and the diversity of natural river habitats as a result of the dynamic annual, seasonal and spatial differences in climate, hydrology and water quality.

2) Nam Theun – Nam Kading The fish biodiversity of the Nam Theun/Nam Kading has been studied several times in connection with the planning of hydropower developments in the basin. All studies found a large number of species but there are some differences in the number and species reported. This is partly caused by the seasonal and yearly changes in occurrence and lack of clarity in the taxonomy of the registered fish species in the region.

As an input to the Environmental Assessment of the Theun-Hinboun Hydropower Project (Norpower 1993) a “Study of Aquatic Life” was prepared (Department of Livestock and Veterinary & Burapha Development Consultants, 1992). This study reported 102 fish species in the Nam Kading below Keng Vang Fong. Further upstream, in the Nam Kading and in the reach which is now the THPP Headpond, 79 species were found.

To assess the impacts on fish species of the planned Nam Theun 2 Hydropower Plant, the fish taxonomist Maurice Kottelat carried out several fish surveys in Nam Theun/Nam Kading Basin (Kottelat 1996, 1997 and 2002). In total, 71 fish species were identified of which a large percentage had not been previously recorded in Laotian waters.

Eleven fish species were registered as new to science. These species were:

• Bangana elegans • Danio fangfangae • Rhodeus laoensis • Scaphognathops theunensis • Nemacheilus arenicolus • Schistura atra • Schistura nudidorsum • Schistura obeini • Schistura tubulinaris • Rhinogobius lineatus • Tor ater

The populations of some of these endemic species are to some extent impacted by the dam and headpond of the THPP, but none of them seem to have disappeared. They can still be found in the Nam Theun upstream of the headpond.

Fish species in the Nam Kading reach downstream of the Keng Vang Fong rapids are similar to the fish species that can be found in the Mekong mainstream. The composition of species in the upstream and rapids flowing through part of the Nam Kading and in the Nam Theun differs greatly from those found in the slow flowing lowland reach.

Biologists and taxonomists, who carried out their fish surveys in Nam Theun/Kading only during the dry season, assumed that Keng Vang Fong and the other numerous rapids in the Nam Kading formed an obstacle for upstream fish migration from the Mekong even before the construction of the Theun-Hinboun Weir. However, at least one aquatic species belonging to the long distance migrating fish


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family Pangasiidae swims from the Mekong mainstream up into tributaries in August/September to spawn in rapids. With the establishment of the headpond weir the upward migration of fish has been blocked for most of the year. However, in the peak of the wet season (September) the weir is submerged and some long distance migrating fish are able to pass to upstream waters.

3) Nam Gnouang and Theun-Hinboun Headpond,

The 25 meter high Theun-Hinboun Weir has changed part of the Nam Theun and Nam Gnouang Rivers into a “lake like” water body with a surface area of 6.3 km2. The water level of the headpond is maintained at 397-400 masl but reaches 410 masl during high floods.

A habitat change has resulted in the disappearance of many of the original fish species but has allowed the proliferation of others. Presently, the introduced fish species, common carp (Cyprinus carpio), forms an important part of the fish yield of Theun-Hinboun Headpond. The carp has invaded the headpond after the disappearance of more than one-third of the originally occurring fish species. The carp is confined to the slow moving water of the headpond and has not been able to establish populations in the fast flowing rivers further upstream.

The fish species composition of the Nam Gnouang upstream of the headpond does not seem to have been significantly changed by the THPP. In the first years after the filling of the headpond, a temporary increase in fish catch was observed, likely due to upstream factors and creation of the headpond, but this situation has now stabilised.

4) Nam Hai and Nam Hinboun.

The Nam Hinboun river system is found to be even richer in species than the Nam Theun/Nam Kading. In the “Study of Aquatic Life” (Department of Livestock and Veterinary & Burapha Development Consultants, 1992) 118 fish species are listed from the Nam Hinboun. Due to the level and slow flowing character of this river, the species composition of the Nam Hinboun is more similar to the Mekong mainstream and the lower part of the Nam Kading than to the Nam Theun.

5.3.3 Fish Production

1) General The fisheries of the Nam Theun/Nam Kading and Nam Hinboun river basins are to a great extent influenced by the fish migration patterns of refuge, spawning and feeding areas. Fish migrate between deep pools, floodplains, rapids, tributaries, ephemeral streams, ponds, paddies and backwaters. Long distance migrating fish species migrate upstream from the Mekong, particularly in the months of August/September when water levels in tributaries are high.

While extreme floods may result in reduced fish catch at upstream locations, the area, duration and frequency of flooding caused by the Mekong mainstream are largely determining the total annual fish production of the Mekong Basin as a whole, including the Nam Hai/Nam Hinboun Basin. Since the annual floods fluctuate significantly, annual fish production and fish yields differ accordingly. Recruitment and production of Pa Soy (Pa Soy is the local name for mix of juveniles from about 25 different fish species) in the Nam Hinboun floodplain depend on the level, duration and frequency of floods. Pa Soy is caught when they migrate from the floodplains and streams up into the Nam Hinboun.

The inherent complexity of monitoring many fish species, large natural changes in ecological conditions and changes in use of fishing gear and level of total fishing efforts makes it difficult to analyse the developments in fish production and fish catch. For instance, the impacts on fisheries of the THPP have been difficult to isolate from changes resulting from natural causes and other development factors.

2) Nam Kading/Nam Theun In the Nam Kading, significant fishing takes place only directly downstream of the headpond weir and in the reach between Keng Vang Fong, at the border to the Nam Kading NPA, and the confluence with the Mekong. The lack of permanent settlements and difficult access restricts the fishing activities


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inside the NPA.

Villagers who fish the Nam Kading in the first few km downstream of the weir have reported a reduction of abundance of certain fish species in their catch after the construction and operation of THPP. However, they did not notice any disappearance of specific fish species in their catch.

Downstream of Keng Vang Fong the changes caused by the THPP in hydrology and water quality are observed mainly in the dry season.

The flow volume and the water velocity have been reduced and have resulted in the deposition of finer sediments. Two bottom dwelling fish species have disappeared from the reach most likely because of a change from sandy to muddy conditions. The change in substrate has, however, led to the establishment of new aquatic plant species and new mussel species. Annual village fish yields have reportedly decreased significantly downstream of Keng Vang Fong. However, the total fishing effort in this stretch of the river has increased considerably since the operation of THPP. The decreased annual village fish yields are more likely to have been caused by the increased fishing efforts than by the diversion of water caused by the THPP (Schouten et al. 2004).

In the Nam Mouan, local fishermen report that their annual catch has changed little. THPP has only caused a slight decrease in water levels during the dry season.

At the upstream headpond, the blockage of migration opportunities by the THPP weir does not seems to have had any significant impact on the species composition downstream and upstream of the weir. The upstream fish species appear to be able to fulfil their complete life cycles upstream of the dam. Villagers at upstream locations of the headpond have reported a decrease in annual catch from the previous year. However, the fish yields appear to have decreased mostly as a result of increased fishing efforts, due to increased access to markets to sell fish, and background impacts on aquatic habitats and water quality. Ongoing large scale fishing practices in the Nam Katha and Nam Phao and ongoing destructive fisheries with explosives and use of pesticides in the Nam Theun do not contribute to the sustainability of annual village fish yields.

3) Nam Gnounag and Theun-Hinboun Headpond Due to the reduction in the number of fish species it would have been expected that the fish yields from the headpond area would have declined. However, the loss in species seems to have been more than compensated for by the proliferation in the headpond of the carp (Cyprinus carpio). This exotic fish species has become the most common species in the annual village fish yields along the headpond and has largely compensated the reduction of annual village fish yields resulting from loss of fish species.

The stable increase in water depth has caused a loss of aquatic vegetation from the headpond area. This has impacted those people living around the headpond who used to harvest such aquatic weeds for consumption. On the other hand some fauna has benefited. For example, one snail that normally occurs in stagnant waters and paddies has proliferated in the headpond. People harvest this snail for consumption and it also serves as the main food source for the carp.

What is said about the Nam Theun and its tributaries upstream the headpond is also valid for the Nam Gnouang.

4) Nam Hai and Nam Hinboun At upstream locations of the Nam Hai, the annual village fish yields stayed more or less the same or even increased after THPP came into operation. The positive changes have been seen in the dry season. Before the power plant was established this reach went almost dry, but now the power plant releases water into the Nam Hai year-round.

Further downstream in the Nam Hai and in the Nam Hinboun down to the Mekong River, the village fish yields have reportedly shown a significantly decline. The discharges from the power plant have caused riverbank erosion, downstream sedimentation, drastic morphologic changes and extreme water level fluctuation (average of 2 m in dry season). High turbidity and high flows which earlier only


32

occurred as a wet season phenomenon are now permanent features of the river.. It also seems that the increased sediment transport in the Nam Hinboun caused by the intermittent flow releases have “filled” the deep pools of the river and thus destroyed important fish production habitats and fishing sites.

This has resulted in a situation where local people can no longer harvest aquatic vegetation or collect snails, mussels and shrimps from the Nam Hinboun mainstream. These items represent important parts of the aquatic food chain and this has thus resulted in a decline in fish productivity and village fish catches. Discharges of suspended solids and heavy metals from tin mines into the Nam Theuk and Nam Pathaen and subsequently into the Nam Hinboun have exacerbated the negative impacts on fish yields in the lower reaches of the Mekong.

In the Nam Hinboun, upstream of the confluence with the Nam Hai, the project induced backwater effects are recorded up to the village of Nasangkham. The annual village fish yields in this stretch of the Nam Hinboun have increased since the power plant started operation due to higher water levels during the dry season. However, the annual village fish yields in villages along the Nam Hinboun upstream of Nasangkham have declined. This indicates that, similar to the lower Nam Kading, the decrease in fish catches in the Nam Hinboun Basins can be partly be attributed to factors such as over-fishing and unsustainable fishing methods in addition to the morphologic and flow changes due to the THPP.

6 LA ND COV ER A ND LAND US E The basin of the Nam Theun/Nam Kading, Nam Hinboun and Xe Bang Fai, is situated in the central region of Lao PDR which is largely covered by forests and cultivated lands. However, the land use patterns in the basin have been driven by changes in the livelihood approaches of local people and investor strategies. Before promotion of shifting cultivation stabilisation in the early 2000s, the forests in the basin were seriously damaged by the slash-and-burn approach of local people. However, after this period, the basin’s forests were able to grow for almost half a decade which enabled lowland paddy areas to expand together with irrigated plant crop cultivation. Investment in irrigation infrastructure is also increasing..

The major drivers of land use patterns are: rapid population growth, increasing investment in natural resources in the basin, expansion of agricultural and increased investment in hydropower and industrial plants or plant crop plantations.. Dry season paddy and tobacco cultivations are being served by irrigation water while maize, cassava and rubber trees have become industrialised. Large areas of land have been approved for industrial plantation projects, particularly rubber trees in Pakkading, Xe Bang Fai, Nakai, Mahaxay, Hinboun, Nongbok and Viengthong districts. However, the most important land for the village economy and subsistence is the paddy land, since the vast majority of the families grow their own rice. The patterns of land cover in each district are illustrated in Table 5.1 below.

Table 5.1: Land cover classification in the basin

No. Province name

Districtname

Total area (ha)

Residential land (ha)

Agricultural land (ha)

Forest land (ha)

Other land (ha)

1 Borikhamxay Pakkading 239,312 74,681 8,336 110,280 46,015

2 Khammouane Xe Bang Fai 194,183 13,169 11,294 92,310 77,410

3 Gnommalath 157,201 351 5,315 84,273 67,262

4 Nakai 433,272 40,000 2,786 332,635 57,850

5 Mahaxay 140,265 386 7,318 84,881 47,680

6 NongBok 133,587 N.A 2,478 92,929 38,180

7 Hinboun 298,511 929 12,409 37,937 247,23


33

6

8 Borikhamxay Khamkeut 438,648 N.A 13,558 107,070 318,02

0

9 Viengthong 449,931 992 94,649 293,785 60,505


6 . 1 L A N D C O V E R 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 Agricultural activities have also played a major role in changing the land cover pattern in the basin. Noticeably, land cover patterns in each district show a direct relation to the degree of investment in each district. Lowland paddy cultivation and gardening are traditional livelihood practices for the people in the basin, thus the percentage of land covered by lowland paddies and gardens is relatively vast in general. Upland rice cultivation is significant in Nakai and Viengthong districts, industrial trees plantation is undertaken in Pakkading, Xe Bang Fai, Hinboun and Khamkeut districts and in Mahaxay and Viengthong district vast areas of land have been conceded for industrial trees plantation, as illustrated in the Table 5.2 below.

Table 5.2: Agricultural land classification in the basin and marginal area in year 2010

No. Provincename District name

Garden (ha)

Lowland paddy

(ha)

Upland paddy

(ha)

Grazing land (ha)

Tree plantatio

n land (ha)

Land given for

concession (ha)

1 Borikhamxay Pakkading 1,621 7,985 838

2 Khammouane Xe Bang Fai 325 10,980 509

3 Gnommalath 502 5,029

4 Nakai 306 1,985 495

5 Mahaxay 76 6,570 672

6 NongBok 1,512 966

7 Hinboun 7,216 11,083 13 15,140

8 Borikhamxay Khamkeut 2,995 5,715 380 118 4,350

9 Viengthong 19,134 3,544 1,774 9,710 60,487

Total 33,687 53,857 2,649 9,841 20,837 61,159


6 . 2 F O R E S T According to the Forest Law of Lao PDR, issued in 1996 and amended in 2005, the forests in Lao PDR are categorised into five different types: protected forest, reserved forest, production forest, generation forest and degraded forest. However, information about the present forest cover recorded by the district does not relate to these categories. This study uses forest cover information from the Land Use Map 2002 and information acquired from the districts authority and by site observation to investigate the current profile of the forest cover. It has found that the forests in the basin are being continuously seriously impacted by human activities, particularly where there are nearby communities.

Deforestation in the basin continues, with both local people and investors playing a significant role in forest degradation. The main cause of deforestation has changed from slash-and-burn for upland rice cultivation to slash-and-burn for both agricultural plant crops and industrial tree plantation... Upland rice and agricultural plant crop cultivation, as a general practice of the local people, and industrial plantation of cassava, maize and rubber trees by local people and organisations are occurring significantly in the basin. Even though the information only shows significant upland rice cultivation in


34

Nakai and Viengthong districts, forests are generally slashed-and-burned in the basin as previously stated in the sub-section 4.1.

Figure 5.1 below shows forest resources in the basin in 2004.. Areas of plantation and unstocked forests are scattered over the basin, particularly in the Xe Bang Fai Basin, revealing forest degradation in the area.

Figure 5-1: Forest cover in the basin Source: NORPLAN and EcoLao. (2004). Cumulative impact analysis and Nam Theun 2 contributions,

Final report.


35

Table 5.3: Forest cover in the basin and marginal area in year 2010

No.

Province name

District name

Cons

erva

tion

and/

or N

CBA

(h

a)

Gen

erat

ion

fore

st (

ha)

Prod

uctio

n fo

rest

(ha

)

Rese

rved

fore

st

(ha)

Oth

er fo

rest

s (h

a)

1 Borikhamxay Pakkading 80,472 28,762 990 21,289 2 Khammouane Xe Bang Fai 4,202 12,635 84,404 417,292 428,004 3 Gnommalath 30,632 52,417 1,156 34,927 4 Nakai 79,004 50,000 75,780 127,774 54,656 5 Mahaxay 48,537 36,414 110,000 227,345 6 NongBok 80,648 12,243 149,199 7 Hinboun 34,803 152,314 8 Borikhamxay Khamkeut 91,949 2,800 4,320 7,895 130,478 9 Viengthong 199,145 53,530 41,043 50,515

Total 336,275 343,749 347,870 740,953 1,248,727 Source: Field survey from October 2010 to March 2011.

6 . 3 A G R I C U L T U R E The agriculture sector in the basin is very active, particularly in lowland areas. However, there is no irrigation water supply in the wet season, except in Nakai district where rain water is sufficient for cultivation of the small rice fields in the district. As well as rice, several other plant crops are also cultivated in all districts in the basin and its marginal areas. The main plant crops are maize, cassava, tobacco, sweet potato, banana, papaya, chilli, beans and melons, with maize, cassava and tobacco the most common.

Table 5.4: Cultivated land classification in the basin and marginal area in 2010

No. Province name

District name

Main crops Annual average

rice product

(ton)

Wet season Dry season

Maize (ha)

Root crop (ha)

Vegetable (ha)

Others (ha)

Tobacco (ha)

1 Borikhamxay Pakkading 23,157 107 311 113 1044 1,090 2 Khammouane Xe Bang Fai 33,015 76 184 9 529 36 3 Gnommalath 15,087 40 30 45 196 4 Nakai 6,888 82 78 13 41 92 5 Mahaxay 21,681 6 NongBok 3,284 130 99 687 700 62 7 Hinboun 36,574 8 Borikhamxay Khamkeut 21,717 3,340 4,305 9 Viengthong 12,050



36

Table 5.5: Plan for irrigation water supply in the basin and marginal area in 2009 - 2010

No. Province name

District name

Number of irrigation

Plan for irrigation water supply for: Wet season cultivation

(ha)

Dry season paddy

(ha)

Dry season plant crops

(ha) 1 Borikhamxay Pakkading 8 840 420 120

2 Khammouane Xe Bang Fai 8 2,352 2,139 51

3 Gnommalath 11 1,072 843 40

4 Nakai 3 0 140 0

5 Mahaxay 14 868 697 35

6 NongBok 26 4,275 3,527 80

7 Hinboun 31 1,787 1,918 66

8 Borikhamxay Khamkeut 14 274 442 145

9 Viengthong 8 225 281 57

Total 123 11,693 10,407 594

Source: Ministry of Agriculture and Forestry, 2009.

6 . 4 P R O T E C T E D A R E A S

6.4.1 National protected areas Lao PDR ranks as one of the richest countries in South East Asia when it comes to biological diversity. Unfortunately, the increasing degradation of the country’s forest resources and wetlands, combined with intense (illegal) hunting pressure and trade in endangered species continues to put undue pressure on the diversity of plants and animals. In order to counteract this negative trend, Lao PDR has initiated several important actions in biodiversity conservation.

In 1996, Lao PDR ratified the Convention on Biological Diversity (CBD). The obligations of CBD have been followed up with legal and institutional development, as well as by the establishment of 20 National Protected Areas (NPAs), previously labelled National Biodiversity Conservation Areas (NBCAs), covering more than 33,100 km (14% of the land area). In addition to the NPAs, a number of provincial and district protection areas have been established.

There are three NPAs in the direct or indirect impact zone of the THXP (Figure 5.2). These are:

• Nakai Nam Theun NPA covering 353,200 ha of the headwaters of Nam Theun

• Nam Kading NPA covering 169,000 ha of the Nam Kading valley downstream of the existing Theun Hinboun dam

• Phou Hin Phoun or Kammouan Limestone NPA covering 150,000 ha of the southern and eastern catchment of Nam Hinboun.

As a compensation measure of the barrier effect of the Nam Theun 2 reservoir on the Nakai Plateau, a Forest Corridor (Nam Theun Corridor) linking Nam Kading NPA with Phou Hin- boun NPA has been established. This area covers the forests on each side of Nam Theun downstream of the NT2 dam site.

6.4.2 Provincial protected areas In addition to the NPAs, two Provincial Protected Areas (PPAs) are found within or close to the project impact zones (Figure 5.2). These are:

• The Nam Chat/Nam Pan Provincial Conservation Forest consisting of 45,000 ha of largely undisturbed forest. It is located to the east of the planed reservoir area covering the parts of the catchment of Nam Gnouang bordering Vietnam. The area contains large stands of wet


37

evergreen forest and is considered important habitat for rare and highly endangered wildlife species such as the Saola (Pseudoryx nghetinhensis).

• The small Pha Kouanchan PPA covers most of the inaccessible limestone ridge separating the Nam Gnouang reservoir area and the Nam Theun catchment. The most characteristic species found in this PPA are species adapted to steep rock and cave environments, in particular reptiles and bats. The fauna also includes the Laotian rock rat or khanyou (Laonastes aenigmamus), sometimes called the "rat-squirrel". This large rodent, belonging to the ancient fossil family Diatomyidae, was first scientifically described in 2005.

6.4.3 Saola Management Area The Pou Kadoung Saola Management area was proposed in 1996 (WCS/ IUCN 1999). It encompasses the northern section of the Nam Gnouang and the head waters of the Nam Chat, Nam Pan and Nam Heung. This area is considered to be of high importance due to the presence of Saola (Pseudoryx nghetinhensis). Despite its apparent importance, no action has been taken to establish or manage this area.


38

Figure 5-2: Biodiversity conservation areas Source: NT-NKD River Basin Committee (RBC), 2011. Similar to the general situation in Lao PDR, the unique value of the biodiversity in the Borikhamxay and Khammouane provinces is under serious threat. In general for the NPAs in Lao PDR, unsustainable logging and deforestation for agriculture are seen as the most serious threats to biodiversity. In these two provinces, however, and in particular in the western parts, the trade in wildlife is seen as an even more acute problem (IUCN 2000). The centre of this trade is supposed to be Lak Xao and about 60-70 % of the goods are assumed to go to Vietnam and eventually to China.

From, 2012, the NT2 Project will provide the Nakai-Nam Theun NPA with annual funds of 1,200 million USD11. This will be an important contribution to help protect this globally important NPA against

11 Source: Nam Theun-Nam Kading Basin Committee, 2012.


39

further encroachment from loggers and poachers.

At the present time there is almost no control of logging or hunting in these NPAs, which mostly responds to pressure from rapidly expanding markets for timber, wild animals and “wild medicines” in Vietnam and China. It cannot be expected that this situation will change in the near future. Theoretically, plans to extend and link NPAs to form more effective ecosystem assemblies are sound. However, the core problem of how to protect habitats and species in Lao PDR has not yet been solved. The most promising event in recent years has been the emergence of ecotourism. It may be possible to initiate effective conservation by empowering enterprises and communities benefiting from tourism revenues to protect the wild resources on which the tourism is based. This will inevitably be on a small scale and it may be necessary to scale down the ambitious expectations triggered when the NPAs and PPAs were established.

6.4.4 Urbanisation There are an estimated 139 small towns with a high urbanisation rate of 4-5 percent per annum, and many of those are along economic corridors (Samakhomlao, 2010); this includes Parkading, Khamkeut, Nongbok, Hinboun, Xe Bang Fai and Nakai. However, basic infrastructure improvement and population in the central districts of Viengthong, Gnommalath, Mahaxay are increasing even though they are not yet recognised as urban.

7 I N F RASTRU CTU RE 7 . 1 R O A D N E T W O R K A N D T R A N S P O R T

The Nam Theun/Nam Kading Basin covers large areas of both central towns and remote areas; therefore, conditions of roads and transportation differ. The northern parts of Vienthong and Khamkeut districts and the northeastern part of Nakai district are more rural, and some communities can only accessed by road in particular seasons and there is no land-based public transportation. However, most other areas are covered by road networks with increasing public transportation services. Development projects, particularly hydropower projects, are influencing development of infrastructures and transportation in the catchment. Present transportation status is illustrated in Figure 6.1, Table 6.1 and Table 7.4.

Table 6.1: Road networks in the catchment

Province District Total length of roads in the province / district

Total Paved road Gravel pave Earth pave

Borikhamxay Pakkading 119.0 104.6 22.9 246.5

Khammouane Xe Bang Fai 24.7 45.8 149.6 220.1

Gnommalath 76.0 72.2 94.6 242.8

Nakai - 63.7 213.9 277.6

Mahaxay - 146.7 301.9 448.6

NongBok - 152.1 33.4 185.5

Hinboun 97.4 178.4 316.5 592.3

Borikhamxay Khamkeut 86.0 164.1 76.6 326.7

Viengthong 59.2 289.2 348.4

Source: MPWT, 2008. Population and Access Database 2008

In the upstream part of the Nam Theun/Nam Kading and the northern side of Xe Bang Fai, main roads of about 56 km and more than 100 km respectively were constructed and improved by the Nam Theun 2 Hydroelectric Project (NT2). Moreover, 15 remote villages in the Nakai-Nam Theun NBCA were relocated


40

in resettlement schemes in which basic infrastructures were provided. Sixteen rural villages remain in the catchment of the Nam Theun where people are using motor boats for transport to central Nakai (Nam Theun 2 Power Company, 2005).

Figure 6-1: Basic infrastructures in the basin Source: NORPLAN and EcoLao. (2004).Cumulative impact analysis and Nam Theun 2 contributions.

Final report.

7 . 2 E N E R G Y A N D H Y D R O P O W E R Lao PDR’s demand for oil is met mostly by imports and is usually used for transportation purposes. Energy consumption in the country has experienced rapid increase from 1995 to 2000, but has slowly stabilised since 2000 (ADB, 2006).

7.2.1 Hydropower infrastructure There is great potential for hydropower development in the basin. There are two big dams already in the basin, namely the NT2 and Theun-Hinboun, two projects under construction, namely the Theun-


41

Hinboun exp. (NG8) and the Theun-Hinboun expansion, and seven other dam projects have been proposed to be constructed in the basin. Details of these 11 hydropower projects are illustrated in Table 6.2 and details of households with electricity in the catchment are shown in Table 7.4.

Table 6.2: Electricity generation in MK3 River Basin

Project Installed capacity

(MW)

Mean annual energy (GWh)

Supply target Commissi

oned (year)

Status

Nam Theun 2 1,075.0 5,936.0 Lao PDR, Thailand 2009 In operation

Theun-Hinboun 210.0 1,327.0 Lao PDR, Thailand 1998 In operation

Theun-Hinboun expansion

222.0 1,395.0 Lao PDR, Thailand 2012 In operation

Theun-Hinboun exp. (NG8)

60 294.0 Lao PDR 2012 In operation

Nam Theun 1 600 2,371.0 Lao PDR, Thailand 2014 Proposed Nam Hinboun 1 45 173.0 Lao PDR 2020 Proposed Nam Hinboun 2 13 58.5 Lao PDR 2020 Proposed Xe Bang Fai 107 564.2 Lao PDR 2019 Proposed Xe Neua 60 230.0 Lao PDR 2020 Proposed Nam Theun 4 30 130.5 Lao PDR, Vietnam 2020 Proposed Nam Mouan 110 452.2 Lao PDR 2020 Proposed

Source: MRC. (2009). Hydropower Project Database_DB-090204-M


42

Figure 6-1: Location of dam projects Source: MRC. (2010). Initiative on Sustainable Hydropower (ISH) 2011-2015 Document.


43

1) Nam Theun 2 Hydropower Project The Nam Theun 2 Hydropower Project is the largest dam in Laos; located upstream of the Nam Theun it has a reservoir area at full supply level of about 450 km2 and a catchment area of about 3,475 km2. The powerhouse includes four Francis turbines and two Pelton turbines,with a total generating energy of 1,075 MW.

2) Theun-Hinboun Hydropower Project The Theun-Hinboun Hydropower Project is a trans-basin diversion project that diverts water from the Theun-Kading River into the Hai and Hinboun River Basins (MRC, 2009). It is located on the Nam Theun about 100 km upstream of its confluence with the Mekong and creates a catchment area of 8,937 km2. The run-of-river design diverts up to a maximum of 110 m³/s for feeding the two identical vertical Francis turbines for a total power generation of about 210 MW (THPC, 2003).

3) Theun Hinboun exp. (NG8) The Theun Hinboun Expansion Project is composed of two main parts; first is a storage reservoir and a power plant on the Nam Gnouang upstream of the Theun-Hinboun headpond and second is expansion of the Theun-Hinboun Power Plant capacity to take advantage of increased dry season flows facilitated by the improved seasonal storage by the reservoir. The Nam Hai and Nam Hinboun channels downstream of the Theun-Hinboun Power Plant will have to convey an increased water flow volume.

4) Nam Theun-1 The Nam Theun 1 Hydropower Project will be the largest dam in Laos; located upstream of the Nam Kading and creating a reservoir area at full supply level of about 280 km2 and a catchment area of about 14,070 km2. The powerhouse includes three vertical axis Francis turbines, with a total energy generating capacity of 600 MW.

5) Other proposed hydropower projects Prior to September 2008, several hydropower projects had been proposed. The Nam Mouan, Theun Hinboun exp. (NG8), and the Theun-Hinboun expansion are operating on the Theun/Kading River and/or its tributaries; the Nam Hinboun 1 and Nam Hinboun 2 are planned for the Hinboun River; and Xe Ban Fai and Xe Neua are scheduled for construction on Xe Bang Fai. The total plannedcapacity of these proposed eight dams is 1170 MW (MRC, 2010)

8 S OCIA L ECONOMIC PROFILES 8 . 1 A D M I N I S T R A T I V E B O U N D A R I E S

This report takes into account the principle districts which are being significantly affected by the water resources development projects, particularly the hydropower projects in the basin. There are nine districts: Pakkading district, Khamkeut district, Viengthong district and Bolikhan district of Borikhamxay province; and Xe Bang Fai district, Gnommalath district, Nakai district, Mahaxay district, Nongbok district and Hinboun district of Khammouane province. Considered as the districts in the administrative boundary, nine districts are shown in Table 7.1 below.


44

Table 7.1: Administration boundary division of the NT/NKD river basin

Source: Field survey from October 2010 to March 2011. Eleven other districts remain under consideration: Mokmai, Borikhan, Pakxanh, Thaphabath, Bualapha, Thakek, Xaybouathong, Atsaphone, Sepone, Vilabuly and Xaybouly. These eleven districts have a less significant impact on, and lessaffected by, development activities in the basin.

8 . 2 P O P U L A T I O N The basin of the Nam Theun/Nam Kading, Nam Hinboun and Xe Bang Fai covers a large area with a high population. The total population in the basin is 358,563 people across the nine districts as presented in Table 7.2; within this figure Hinboun and Khamkeut districts have the biggest populations at 67,313 and 62,492 respectively. The population is differently distributed over the basin, from a population density of 3 people per square kilometre in Xe Bang Fai district to the the highest density of 34 people per square kilometre in Hinboun district. The people often live in rural areas, particularly in Pakkading district, where the percentage of the population in rural area is 91.6%. However; the average value of the percentage of the population in rural area is about 61%.

Table 7.2: Population distribution in the river basin

SoSource: Field Source: Field survey from October 2010 to March 2011.

8 . 3 P O P U L A T I O N S T R U C T U R E A N D E T H N I C I T Y The basin is comprised of a total of 19 ethnic groups: Lao Loum, Phou Tai, Xek, Mah Korng, Kim Mou, Karieng, Forngh, Hmong, Meuy, Kouam, Phouane, Men, Khung, Lao Deng, Eth, Pao, Yuol, Toomh and Khaah. However, the principle ethnic groups are Lao Loum, Phou Tai, Mah Korng, Kim Mou and

No. Province name District name Total area (ha) Area in the basin (ha) Percent (%)

1 Borikhamxay Pakkading 239,312 139,982 58.5 2 Khammouane Xe Bang Fai 194,183 93,574 48.2 3 Gnommalath 157,201 155,090 98.7 4 Nakai 433,272 433,271 100.0 5 Mahaxay 140,265 138,967 99.1 6 NongBok 133,587 26,970 20.2 7 Hinboun 298,511 243,629 81.6 8 Borikhamxay Khamkeut 438,648 434,902 99.1 9 Viengthong 449,931 444,028 98.7 Total 2,484,910 2,110,413 -

No. Province District

Population

Num

ber o

f fa

mili

es

Popu

latio

n gr

owth

rate

(%)

Popu

latio

n de

nsity

(p

erso

n/sq

.km

)

Perc

ent o

f po

pula

tion

in

Female Total

1 Borikhamxay Pakkading 23,726 47,819 8,541 8.2 24 91.6 2 Khammouane Xe Bang Fai 13,503 25,035 4,343 10.1 3 61.2 3 Gnommalath 15,440 30,107 6,285 86.7 24 72.7 4 Nakia 11,022 22,077 4,518 N.A 5 41.0 5 Mahaxay 16,701 33,276 6,348 45.4 8 34.0 6 NongBok 22,528 44,090 8,246 89.3 18 38.8 7 Hinboun 34,418 67,313 13,793 18.3 34 47.6 8 Borikhamxay Khamkeut 29,820 62,492 9,526 N.A 25 80.9 9 Viengthong 12,941 26,354 4,018 20.2 6 84.3 Total 180,099 358,563 65,618 - 147 -


45

Hmong, as shown in Table 7.3.1 below. The districts which are ethnically diversity are Gnommalath district and Pakkading district, as there are 14 and 8 ethnic groups respectively.

Table7.3.1: Population breakdown structure and ethnicity


Popu

latio

n

Fam

ilies

in th

e di

stric

t

Percentage of ethnic groups (%)

Num

ber o

f eth

nic

grou

ps

in th

e di

stric

t

Lao

Loum

Phou

Tai

Mah

kor

ng

Kim

Mou

Hmon

g

Oth

er

Tota

l

1 Borikhamxay Pakkading 47,819 8,541 77.2 5.9 0 4.5 8.8 3.6 100 8

2 Khammouane Xe Bang Fai 25,035 4,343 31.9 24.5 0 5.4 25.1 13.1 100 5

3 Gnommalath 30,107 6,285 0 34.0 0 0 31.1 34.9 100 14

4 Nakia 22,077 4,518 58.4 24.1 17.5 0 0 0 100 3

5 Mahaxai 33,276 6,348 63.9 22.9 13.2 0 0 0 100 3

6 NongBok 44,090 8,246 60.8 3.9 0 29.5 0 5.9 100 4 7 Hinboun 67,313 13,793 35.0 0 0 65.0 0 0 100 3

8 Borikhamxay Khamkeut 62,492 9,526 95.6 0 0 0 0 4.4 100 2

9 Viengthong 26,354 4,018 100 0 0 0 0 0 100 1


Regrettable, there is no age breakdown in the population database in either the district level or provincial level. However, there are nationwide average values in the Census 2006, conducted by the National Statistics Centre of Lao PDR. These are summarised in Table 7.3.2 below:

Table7.3.2: National age distribution in Lao PDR in 2006

Percentage of the population in age ranges:

<15 years 15 – 24 years 25 – 59 years ≥ 60 years

Female 38.5 21.0 34.5 6.0 Male 39.6 21.0 33.9 5.5 Average 39.0 21.0 34.2 5.8

Source: National Statistics Centre, 2006 8 . 4 A C C E S S T O P U B L I C S E R V I C E S

A large portion of the villages in the basin are located in rural areas therefore accessibility to basic infrastructures and services vary. The principle basic public services available in the area are district or community markets, electricity, main and access roads, schools, health facilities, irrigation and clean water supplies, on land transport and navigation across the Mekong River. Table 7.4 below shows some public services and infrastructures in the basin; however, some of these services are described in more detail in the following sections.


46

Table7.4: Availability of basic infrastructures and services

No.

Prov

ince

:

Dist

rict:

Tota

l vill

ages

in th

e di

stric

ts

Tota

l fam

ilies

in th

e di

stric

ts

Num

ber o

f mar

kets

Num

ber o

f vill

ages

with

el

ectr

icity

Num

ber o

f fam

ilies

with

el

ectr

icity

con

nect

ion

Num

ber o

f vill

ages

with

all-

wea

ther

road

acc

ess

Num

ber o

f prim

ary

scho

ol in

th

e di

stric

t

Num

ber o

f loc

atio

n of

ferr

y cr

ossi

ng th

e M

ekon

g riv

er in

th

e di

stric

t

1 Borikhamxay Pakkading 51 8,541 4 21 25 35 2 2 Khammouane Xe Bang Fai 45 4,343 2 34 3,573 34 43 2 3 Gnommalath 44 6,285 2 43 7 56 3 4 Nakia 29 4,518 1 14 25 16 1 5 Mahaxai 70 6,348 1 54 59 68 0 6 NongBok 55 8,246 4 55 52 49 1 7 Hinboun 137 13,793 1 118 8,801 94 128 1 8 Borikhamxay Khamkeut 64 9,526 1 56 8,292 52 49 0 9 Viengthong 46 4,018 1 25 12 46 0

Source: Field survey from October 2010 to March 2011

8 . 5 H E A L T H C A R E There are district hospitals in each district in the basin, and in the more developed towns along the main roads. Those areas with large infrastructure development projects will also have medical facilities, with Hinboun, Nong Bok and Khamkeut districts having one, two and three health clinics respectively(). Both district health workers and village health workers attend the district hospitals and provide basic medicine boxes. However, accessibility to health services differs between the towns and the remote areas; people in remote areas generally have quite limited access to health care service and moreover some villages located far away from the central district and with noroad access have to either use a farm tractor or carry the patient to hospital.

The five most common reported diseases and infections are typhoid, dysentery, diarrhoea, pneumonia and dengue fever and the reported main causes of death are old age, dengue and other. However, it is noticeable that dengue has caused more deaths than old age.


47

Table7.4: Availability of basic infrastructures and services

No. Province: District N

umbe

r of h

ealth

clin

ics

Num

ber o

f hos

pita

sl

Num

ber o

f dis

tric

t hea

lth st

aff

Num

ber o

f vill

age

heat

h w

orke

rs

People affected by the most common reported diseases

(%)

People dying in the year, and main cause of

death (%)

Typh

oid

Dyse

nter

y

Diar

rhoe

a

Pneu

mon

ia

Deng

ue

Old

age

Deng

ue

Oth

er

1 Borikhamxay Pakkading 0 1 8 21 2.5 7.2 0.0 3.4 68.0 10.0 0.0 55.5

2 Khammouane Xe Bang Fai 0 1 55 12 4.0 6.4 5.0 1.1 83.4 0.0 37.5 62.5

3 Gnommalath 0 1 51 9 6.6 4.2 0.0 0.5 74.0 0.0 0.0 33.5

4 Nakia 0 1 37 5 0.0 0.0 3.3 2.6 0.0 0.0 45.0 0.0

5 Mahaxai 0 1 23 25 7.0 10.3 0.0 0.0 57.7 7.0 0.0 88.0

6 NongBok 2 1 78 18 3.8 3.7 7.0 1.4 0.0 5.0 57.5 0.0

7 Hinboun 1 1 68 23 8.0 0.0 0.3 0.7 0.0 0.0 17.0 55.0

8 Borikhamxay Khamkeut 3 1 70 19 0.0 7.8 0.0 1.7 52.3 4.0 0.0 0.0

9 Viengthong 0 1 34 10 9.1 0.0 0.0 1.7 0.0 0.0 34.2 10.0


8 . 6 E D U C A T I O N A N D I L L I T E R A C Y On average, 90 % of all villages have primary schools, and 15% of all villages have secondary school facilities. There are primary schools in every village in Gnommalath district and Viengthong district. However, the weakest district is Nakai, as there are only 16 primary schools in a total of 29 villages, and the percentage of children attending primary and secondary schools is 7.9% and 2.9% respectively, which is also lower than in other districts. In contrast, Khamkeut district in Borikhamxay province has 29.3% and 26.3% of children attending primary and secondary schools respectively. Another key measure is that there are no illiterate people in the basin except in Viengthong district in Borikhamxay province where 2.3 % of people are illiterate.


48

Table7.6: Educational facilities and children attending school

No Province District Pe

rcen

t of p

rimar

y sc

hool

com

pare

to

tota

l num

ber o

f vill

ages

(%)

Number of children attending primary

school

Perc

ent o

f sec

onda

ry sc

hool

com

pare

to

tota

l num

ber o

f vill

ages

(%)

Number of children attending secondary

school

Percentage

of Illitera

cy (%)

Girl

s

Tota

l

Com

pare

to to

tal

popu

latio

n (%

)

Girl

s

Tota

l

Com

pare

to to

tal

popu

latio

n (%

)

Mal

e

Fem

ale

1 Borikhamxay Pakkading 68.6 3,204 6,573 13.7 13.7 1,342 3,303 6.9 0 0 2 Khammouane Xe Bang Fai 95.6 1,867 3,986 15.9 15.6 1,114 2,333 9.3 0 0

3 Gnommalathh 100.0 2,901 5,799 19.3 11.4 667 1,185 3.9 0 0

4 Nakia 55.2 864 1,751 7.9 10.3 315 632 2.9 0 0 5 Mahaxai 97.1 3,069 6,366 19.1 17.1 856 1,992 6.0 0 0 6 NongBok 89.1 2,375 5,098 11.6 20.0 2,322 4,624 10.5 0 0 7 Hinboun 93.4 4,814 10,039 14.9 13.9 1,763 4,198 6.2 0 0 8 Borikhamxay Khamkeut 76.6 8,694 18,292 29.3 23.4 7,813 16,438 26.3 0 0

9 Viengthong 100.0

2,438 5,353 20.3 10.9

789 2,106 8.0

1.1

2.3


8 . 7 W A T E R S U P P L Y A N D S A N I T A T I O N

Table 7.1 below shows the numbers and percentages of villages that have a clean water supply and sanitation.. The basin is distinct in that there are plenty of natural water resources and many local villages use water from shallow wells and/or directly from streams. Nongbok district and Hinboun district have the lowest percentage of families with a clean water supply; however, there are sanitation usage is higher in these two districts. The district with the lowest sanitation use (26%) is the Gnommalathh district.

Table7.7: Water supply and sanitation data in the basin


Tota

l vill

ages

in th

e di

stric

ts

Tota

l fam

ilies

in th

e di

stric

ts

Num

ber v

illag

e ha

ve

clea

n w

ater

supp

ly

Num

ber o

f fam

ilies

ha

ve c

lean

wat

er su

pply

Num

ber v

illag

e ha

ve

sani

tatio

n

Villa

ge h

ave

clea

n w

ater

su

pply

(%)

Perc

ent o

f fam

ilies

hav

e sa

nita

tion

(%)

1 Borikhamxay Pakkading 51 8,541 20 7,819 25 39.2 48.7 2 Khammouane Xe Bang Fai 45 4,343 34 3,573 44 75.6 35.5 3 Gnommalathh 44 6,285 37 3,107 28 84.1 26.0 4 Nakia 29 4,518 16 7,973 16 55.2 33.4


49

5 Mahaxai 70 6,348 58 3,989 5 82.9 35.0 6 NongBok 55 8,246 11 7,780 44 20.0 98.2 7 Hinboun 137 13,793 25 6,480 10 18.2 65.0 8 Borikhamxay Khamkeut 64 9,526 32 6,554 15 50.0 68.8 9 Viengthong 46 4,018 33 3,050 11 71.7 55.0


8 . 8 E L E C T R I C I T Y S U P P L Y

Within these rivers basins, between 70% and 100% of households have access to electricity, with this being higher in the municipal areas where there are economic activities and better basic infrastructure, such as roads. However, households in three rural districts still have limited access to electricity: Pakkading district (41.2%), Nakai district (48.3 %) and Viengthong district (54.3%). See Table 7.8 below.

Table 7.8: Villages and households with access to electricity in the basin

No. Province: District:

Tota

l vill

ages

in

the

dist

ricts

Tota

l fam

ilies

in

the

dist

ricts

Num

ber o

f vi

llage

s with

el

ectr

icity

Num

ber o

f fa

mili

es w

ith

elec

tric

ity

conn

ectio

n

Elec

tric

ity

cove

rage

pe

rcen

tage

(%)

1 Borikhamxay Pakkading 51 8,541 21 41.2 2 Khammouane Xe Bang Fai 45 4,343 34 3,573 75.6 3 Gnommalath 44 6,285 43 97.7 4 Nakia 29 4,518 14 48.3 5 Mahaxai 70 6,348 54 77.1 6 NongBok 55 8,246 55 100.0 7 Hinboun 137 13,793 118 8,801 86.1 8 Borikhamxay Khamkeut 64 9,526 56 8,292 87.5 9 Viengthong 46 4,018 25 54.3


9 ECON OM IC DEV ELOP MEN T Together these three rivers sustain the livelihoods of diverse ethnicities and poor communities in the central provinces of Lao PDR, who rely on them for fishing, farming and maintaining their cultural traditions. The Nam Theun/Nam Kading, Nam Hinboun and Xe Bang Fai are a source of immense biodiversity, are rich in fish and are critical for the migration of fish species travelling to the Mekong Basin in Laos and Thailand. All basins report a decline in fish production from a combination of loss of habitat, fishing pressure and illegal fishing methods; in the future these issues will increase due to changes caused by hydropower dams. The pressures on water resources across the Nam Theun/Nam Kading, Nam Hinboun and Xe Bang Fai Basins are intensifying. These pressures could, in the future, undermine the ability of Laos and Thailand to meet their long term development objectives.

9 . 1 A G R I C U L T U R E In the catchment, agricultural practices are similar in all districts. Rice has always been the major agricultural product but other cash crops have also been dominant sources of income. The popular cash crops are vegetables, maize, cassava, tobacco, sweet potato, banana, papaya, chilli, beans and melons, with maize, cassava and tobacco the most dominant. Furthermore, some cash crops are increasingly industrialised. The most industrialised plant crops are rubber, cassava, maize, tobacco, teak, and sugarcane. However, dry season rice production is continuous promoted; many irrigation


50

schemes have been constructed and are continually maintained (see sub-section 8.7). Some details of plantations are shown in the table below.

Table 8.1: Cultivation in the catchment

Source: Field survey Source: Field survey from October 2010 to March 2011.

9 . 2 F I S H E R I E S The field survey found that for the majority of people, running a fishery is a dominant occupation and an important income source. Fishing is in both these rivers and their tributaries. However, many households breed fish in either their own fishponds or in nets in the rivers. More details are provided in Table 8.2 below.

No. Province District Cultivated land and type of plant crops

Majority of cash crops

Majority of industrial crops

1 Borikhamxay Pakkading Paddy and orchards 11,005 ha; Vegetables 206 ha; Industrial crops 1,396 ha

Tobacco leaf, pineapple, cassava, rice, etc.

Rubber trees, teaks, eucalyptuses, and etc.

2 Khammouane Xe Bang Fai Paddy & orchards 7,407 ha; Vegetables 763 ha; Industrial crops 14,982 ha

Pineapple, rice, raw rubber, etc.

Rubber trees, eucalyptus and vegetation

3 Gnommalath Paddy and orchard 4,530 ha; Vegetables 497 ha; Industrial crops 10,664 ha

Cassava, maize, rice, etc.

4 Nakia Paddy and orchards 1.491 ha; Vegetables 492 ha; Industrial crops 818 ha

Cassava, rice, tobacco leafs, etc.

5 Mahaxay Paddy and orchards 7,320 ha; Vegetables 876 ha; Industrial crops 133

Rice and vegetables

6 NongBok Paddy and orchards10,535 ha; Vegetables 1,707 ha; Industrial crops 150 ha

Rice, maize & vegetables

Rubber trees, cassava, sugarcane and etc.

7 Hinboun Paddy and orchards 10,834 ha; Vegetables 547 ha; Industrial crops 2,990 ha

Rice, cassava, maize & vegetables

8 Borikhamxay Khamkeut Paddy and orchards 5,695 ha; Vegetables 5,519 ha; On land paddy 110 ha

Rice, cassava, maize & vegetables.

Industrial plantations is a policy of the government

9 Viengthong

Paddy and orchards 2,135 ha; Vegetables 919 ha; Industrial crops 1,353 ha; On land paddy 1,774 ha

Rice, cassava & vegetables

Industrial plantations is a policy of the government


51

Table 8.2: Fishery activities in the catchment

No. Province name District name Fishery activities

1 Borikhamxay Pakkading Fishing is a dominant occupation of the local people along the Nam Kading.

2 Khammouane Xe Bang Fai Fishing is a dominant occupation of the local people along the Xe Bang Fai. However, many people have their own fishponds.

3 Gnommalath Fishing is a dominant occupation of the local people along the Xe Bang Fai as Ban Hai, Ban Phonkeo, Ban Hadsone and Ban Kengmouang. However, some people have their own fishponds.

4 Nakai Fishing is a dominant livelihood activity of the majority of people. The outstanding record is in year 2009, when fish production was 23.74 tonnes, mostly through traditional fishing.

5 Mahaxay Most people have fishing as a dominant occupation. Furthermore, they breed fish; there are 219 fishponds in the district in an area of 1,375 ha.

6 NongBok Fish production is a main income source

7 Hinboun The majority of people earn their income from fishing. However people in 38 villages also breed fish in their own fishponds with a total of 197 fishponds and area of 195.35 ha.

8 Borikhamxay Khamkeut Most people earn income from fishing and breeding fish in their own fishponds and also in nets.

9 Viengthong The majority of people earn their living by fishing along several rivers in the district.

Source: Field survey from October 2010 to March 2011 9 . 3 M I N I N G , I N C L U D I N G S A N D A N D G R A V E L

Nam Theun/Kading: Deposits of gold, lead, graphite and tin are believed to be present in the Nam Gnouang and Nam Theun catchments and some small scale commercial mining is taking place.

Some alluvial panning for gold is practiced by villagers during low water levels (at the end of the dry season) on the Nam Gnouang and the Nam Kading. Alluvial deposits are dredged by hand or mechanized dredgers from the bottom of pools and then panned for gold. In particular, the villagers of Ban Kengbit on the Theun-Hinboun Headpond and Ban Phonsi in the lower Nam Kading are involved in alluvial panning of gold deposits.

Alluvial gold is also found in Nam Kata, a stream entering the Nam Theun tributary, and Nam Phao, downstream of Lak Xao. Prospects exist for commercial exploitation. At present gold is extracted by artesian means, which includes the use of mercury. THPC is presently monitoring these rivers due to the locations of proposed resettlement sites along the Nam Phao and the Nam Phiat.

Nam Hinboun: Located on the Nam Pathen, a tributary of the Nam Hinboun, is the Maouang Kai tin and lead mine. The mine has been worked since about 1930, originally established under the French colonial regime. It is a typical small washing and screening process applied to a local lead ore deposit in silt. It uses water pumped from the Nam Pathen stream to wash out the ore. There are no settling ponds and the sediment rich water is fed directly back into the Nam Pathen leading to downstream water quality problems. Some of the discharge water also enters the Nam Thak through an underground river.

Several unexplored and un-mined iron and tin deposits are known to occur in Khammouane province and small scale operations have already started at some of these sites.


52

Table 8.3: Mine extractions in the catchment

No. Province name District name Soil, stone, sand and gravel extraction

1 Borikhamxay Pakkading

Extraction of sand, gravel and fertilized soil. The products are: gravel 3,420 m3/y; sand 5,648 m3/y; and soil 1,300 m3/y. Cooper extraction at Paksan village and lead extraction at Sang and Thongnamee villages.

2 Khammouane Xe Bang Fai Stone extraction for construction projects.

3 Gnommalath Extraction of stone for roads construction projects and lime stone for cement production.

4 Nakai None.

5 Mahaxay Clay and lime stone extraction for cement production in the district with cement production capacity of 2,500 ton/day.

6 NongBok

Extraction of magnesium salt and potassium salt by the Vietnamese and Chinese and river sand extraction in one location. 5 mortar-cement block factories, 7 drinking water plants and 206 rice mills.

7 Hinboun

17 stone extraction set-ups:9 units are extracting, 2 units are conducting surveys, 2 units are waiting for permission and 1 unit is on-hold. The products: crushed stone, 277,835 m3/y and river sand & -gravel,2,760 m3

8 Borikhamxay Khamkeut Monitoring the extracting activities of 24 stone extraction units. The products: crushed stone for construction,8,550 m3l sand, 23,665 m3; and fertilized soil, 4,500 m3.

9 Viengthong None


9 . 4 I N D U S T R Y

There are several large scale factories and many medium and small scale factories in the catchment. They include sawmills, rice mills, furniture factories, drinking water plants, crushing plants, cement plants, ice making plants and mortar-cement block plants. Most of the industrial factories are located in the more urbanised districts, such as Nongbok, Khamkeut and Hinboun. However, sawmills are scattered. Most of the production is distributed within the country.

9 . 5 H Y D R O P O W E R There are two large scale hydroelectric projects in the catchment, namely NT2 and Theun Hinboun, with NT1 being planned. When NT1 is complete, they will be the biggest dams in Laos, with a total installed capacityof 2167 MW and providing important contributions to the country’s economy.

The government of Lao PDR recognises the potential for hydropower development, particularly in the basin, and has incorporated this into its plans for developing the economy of the country. Notwithstanding, 11 hydropower projects, with a total installed capacity of about 1170 MW, have been constructed, or are planned for construction, in the basin.

9 . 6 T O U R I S M The MK3 River catchment is home to sites of historical, cultural and natural interest to tourists. More than 200 tourist attractions are scattered within and near the catchment and are being promoted as such.. The table below describes these sites.


53

Table 8.5: Touristic activities in the catchment

No. Province name District name Tourism

1 Borikhamxay Pakkading 3 tourist attractions, 1 place had been officially conserved, 36 tourist groups and earned 244 million kip.

2 Khammouane Xe Bang Fai 21 tourist attractions: 1 cultural, 6 historical and 34 natural.

3 Gnommalath

Phou Hinboun National Conservation Forest, Khou Hou Cave, 4 historical tourist attractions, 6 cultural tourist attractions. Recently, construction has taken place atNang Loth Cave at Naden village and Nong Cave at Pheingsang villages which will facilitate tourism to these caves.

4 Nakai 15 tourist attractions: 11 cultural, 1 historical and 3 natural.

5 Mahaxay 20 tourist attractions: 15 cultural and 5 natural, including Pha Nang Cave, Pha Katao Cave, Jeb Cave, SiengSone waterfall and Khoun Oula .

6 NongBok 10 historical tourist attractions and 3 natural tourist attractions.

7 Hinboun Hinboun mountain national conservation area, Khoun Kongleng, Khoun Kheh, Thawada waterfall. And 34 other tourist attractions: 32 natural and 2 historical.

8 Borikhamxay Khamkeut

92 tourist attractions increase 22.4 % of tourists and 1 more natural site inaugurated during the year. Survey of the Phiod River conducted for possible construction of new tourist attraction.

9 Viengthong Development of 1 or 2 tourist attractions planned, for example, Phathong and Theub Caves.

Source: Field survey from October 2010 to March 2011 9 . 7 I R R I G A T I O N

Having presented some aspects of irrigation in the catchment in sub-section 5.3, this sub-section presents the irrigation development status in the catchment. Irrigation development has been a key component of the Socio-Economic Development Plans of the government of Lao PDR, since the Fifth Five year plan in the early 2000s in order to yield cultivated products, particularly rice, as a development strategy for poverty reduction nationwide.

A summary of more than 100 irrigation schemes constructed in and at the marginal area of this catchment is presented in Table 8.6. There are currently yearly plans to supply irrigation water for cultivation.


54

Table 8.6: A summary of the irrigation schemes and water supply schedules in the catchment

9 . 8 T R A N S P O R T A T I O N

Since development of the on land transportation network in the catchment is in progress, water transport is playing a smaller role. There is neither a major transport port nor a ferry crossing on the Nam Theun/Nam Kading; in practice, people use motor boats for crossing the river between neighbouring villages However, there is single-weather road access to several villages in remote areas, particularly in the northern parts of Viengthong and Khamkeut districts and the northeastern part of Nakai district; people in those villages are using wooden boats for transport to the central districts. In the case of Xe Ban Fai, transport on the river is inconvenient; only small volumes can be transported within fifty kilometres from the confluence with the Mekong River. In the wet season, the river is navigable for ships with a capacity of up to 5 tonnes, in the dry season the capacity of the ships is limited to 0.2 tonnes. Villagers report that their use of the Xe Bang Fai for transportation during the dry season is less than in the past, and there are only a few regular passenger boat services operating in the lower section of the river12.

12

Source: MRC, 2009b, pp.9-10.

Wet Season Dry Season paddy Dry Season plant crops

(ha) (ha) (ha)1 Borikhamxai Pakkading 8 840 420 320

2 Khammouane Xe Bangfai 8 2,325 2,139 51

3 Khammouane Gnommalath 11 1,072 843 40

4 Khammouane Nakai 3 - 140 -

5 Khammouane Mahaxay 14 868 697 35

6 Khammouane NongBok 26 4,275 3,527 80

7 Khammouane Hinboun 31 1,787 1,918 66

8 Borikhamxai Khamkeuth 14 274 442 145 9 Borikhamxai Viengthong 8 225 281 57

No. Name of DistrictNumber of irrigation

sheme

Schedule of Water Supply in 2009-10

Name of Province


55

1 0 REF EREN CES ADB. (2006). Lao PDR _Country synthesis Report on Urban Air Quality Management. Philippines: ADB.

Retrieved 10th September 2011, from http://www.google.la/#hl=en&q=urbanization+in+Lao+PDR&oq=urbanization+in+Lao+PDR&aq=f&aqi=&aql=&gs_sm=e&gs_upl=32837l36258l0l37745l4l4l0l3l0l0l1948l1948l8-1l1l0&fp=78e7fb070209b77a&biw=1199&bih=637

MRC. (2009). Basin Development Plan Programme, Phase 2. Hydropower sector review for the joint basin planning process. Retrieved 09th September 2011, from http://www.mrcmekong.org/download/programmes/bdp/BDP2-Regional-Hydropower-Sector-Review-5-Mar-09.pdf

MRC. (2009b). Integrated Flood Risk Management Plan for the Lower Xe Bang Fai area in Lao PDR. Draft Final Report, Volume 6B. pp.9-10. Retrieved 05th October 2011, from http://www.mrcmekong.org/download/fmmp-reports/V6B_Lower%20Xe%20Bang Fai%20IFRM%20Plan_GSL_22122009.pdf

MRC. (2010). Initiative on Sustainable Hydropower (ISH) 2011-2015 Document. Retrieved 09th September 2011, from http://www.mrcmekong.org/download/free_download/hydropower/ISH-2011-2015-Initiative-Final-version-30Oct.pdf

NORPLAN and EcoLao. (2004). Cumulative impact analysis and Nam Theun 2 contributions. Final Report.

NTPC. (2005). Environmental Assessment and Management Plan. Nam Theun 2 Hydroelectric Project.

NTPC. (2011). Technical data of monthly areal rainfall of Nam Theun 2 Basin for Year 2010

NORPLAN A.S. (2008). Theun Hinboun Expansion Project. Final EIA/EMMP. Section 1 EIA.

Samakhomlao. (2010). High urbanization rate of 4-5% per annum. Retrieved 10th September 2011, from http://laomate.activeboard.com/t34513029/laos-high-urbanization-rate-of-4-5-percent-per-annum/

THPC. (2003). Theun-Hinboun Power Plant. Operation Handbook.

WCS Lao Program (1996). Regional Assessment of the Effects on Wildlife of Proposed Hydropower Projects in the Nam Theun/Nam Kading Watershed.

http://www.google.la/#hl=en&q=urbanization+in+Lao+PDR&oq=urbanization+in+Lao+PDR&aq=f&aqi=&aql=&gs_sm=e&gs_upl=32837l36258l0l37745l4l4l0l3l0l0l1948l1948l8-1l1l0&fp=78e7fb070209b77a&biw=1199&bih=637



http://www.mrcmekong.org/download/programmes/bdp/BDP2-Regional-Hydropower-Sector-Review-5-Mar-09.pdf

http://www.mrcmekong.org/download/programmes/bdp/BDP2-Regional-Hydropower-Sector-Review-5-Mar-09.pdf

http://www.mrcmekong.org/download/fmmp-reports/V6B_Lower%20Xe%20Bangfai%20IFRM%20Plan_GSL_22122009.pdf

http://www.mrcmekong.org/download/fmmp-reports/V6B_Lower%20Xe%20Bangfai%20IFRM%20Plan_GSL_22122009.pdf

http://www.mrcmekong.org/download/free_download/hydropower/ISH-2011-2015-Initiative-Final-version-30Oct.pdf

http://www.mrcmekong.org/download/free_download/hydropower/ISH-2011-2015-Initiative-Final-version-30Oct.pdf

http://laomate.activeboard.com/t34513029/laos-high-urbanization-rate-of-4-5-percent-per-annum/

http://laomate.activeboard.com/t34513029/laos-high-urbanization-rate-of-4-5-percent-per-annum/


56

1 1 A P PEND IX -A IRRIG ATION S CH EMES AND WATER S U PPLY S CH ED U LES IN TH E CATCH MEN T

No. Name of district/ Project name

Location project

Type of activities

Schedule of water supply in 2009-10

Village River

Wet season

Dry season

paddy

Dry season plant crops

(ha) (ha) (ha)

I Pakkading 840 420 320

1.1 Nam Khou Thongnamee Nam Khou Pumping 400 50 40

1.2 Horng Xeng Thongnamee Horng Xeng Pumping 10 50 40

1.3 Nam Bor Thong Harp Nam Bor Pumping 10 20 40

1.4 Somsanouk Somsanouk Mekong Pumping 170 170 40

1.5 Houay Hin Dam Thongnamee Houay Hin Dam Pumping 20 20 40

1.6 Houay Sa Fark Thongnamee Houay Sa Fark Pumping 150 30 40

1.7 Houay Ya Orh Thongnamee Houay Ya Orh Pumping 50 50 40

1.8 Houay Tui Xonh Phansai Houay Tui Pumping 30 30 40

II Xe Bang Fai 2,325 2,139 51

2.1 Ban Had Kham Hieng 1 Had Kham Hieng Xe Bang Fai Pumping 250 220 5

2.2 Ban Had Kham Hieng 2 Had Kham Hieng Xe Bang Fai Pumping 120 160 5

2.3 Ban Na Pork Na Pork Xe Bang Fai Pumping 250 130 7

2.4 Ban Yang Kham Yang Kham Xe Bang Fai Pumping 250 230 5

2.5 Ban Som Sa Ath Som Sa Ath Xe Bang Fai Pumping 145 130 5

2.6 Ban Norng Bone Norng Bone Xe Bang Fai Pumping 60 52 4

2.7 Ban Vang Vueng Phee Vang Vieng Phee Xe Bang Fai Pumping 1,200 1,200 20

2.8 Ban Na Than Na Than Xe Bang Fai Pumping 50 17 -

III Gnommalath 1,072 843 40

3.1 Ban Norng Ping Norng Ping Nam Yom Pumping 100 80 8

3.2 Ban Naphosai Na Pho Sai Nam Yom Pumping 85 72 3

3.3 Ban Phon Toum Phon Toum Nam Yom Pumping 45 30 2

3.4 Ban Boung Bao Boung Bao Nam Yom Pumping 60 51 3

3.5 Ban Keng Lek Keng Lek Nam Yom Pumping 110 103 7

3.6 Ban Si Boun Heuang Si Boun Heuang Nam Yom Pumping 100 80 6

3.7 Ban Houay Yen Houay Yen Nam Yom Pumping 65 70 3

3.8 Ban Thaa Pha Thaa Pha Nam Yom Pumping 80 65 -

3.9 Ban Phon Sied Phon Sied Nam Yom Pumping 77 65 -


57

3.10 Ban Na Ka Tang Na Ka Tang Nam Yom Pumping 70 45 -

3.11 Ban Tha Thoth Tha Thoth Nam Yom Pumping 280 182 8

IV Nakai 0 140 0

4.1 Ban Thaa Phai Ban Thaa Phai Ban Nam Hang Pumping - 50 -

4.2 Khet Mark Feuang Vang Chang Nam Hang Pumping - 55 -

4.3 Khet Teung Beuk Houay Noi Pumping - 35 -

V Mahaxia 868 697 35

5.1 Ban Na Forng Na Forng Xe Bang Fai Pumping 98 35 3

5.2 Ban Dangh Dangh Xe Bang Fai Pumping 150 100 4

5.3 Ban Na Kioe Na Kioe Xe Bang Fai Pumping 65 40 4

5.4 Keng Sa Vang Keng Sa Vang Xe Bang Fai Pumping 35 15 6

5.5 Mahaxia Neua Mahaxia Neua Xe Bang Fai Pumping 100 80 6

5.6 Mahaxia Tai Mahaxia Tai Xe Bang Fai Pumping 150 120 5

5.7 Ban Pho Wa Neua Pho Wa Neua Xe Bang Fai Pumping 80 52 4

5.8 Ban Pho Wa Tai Pho Wa Tai Xe Bang Fai Pumping 80 70 3

5.9 Ban Norng Pa Khao Norng Pa Khao Xe Bang Fai Pumping 60 50 -

5.10 Ban Som Sa Nouk Som Sa Nouk Xe Bang Fai Pumping 50 10 -

5.11 Ban Veun Veun Xe Bang Fai Pumping - 30 -

5.12 Nan Norng Kork Norng Kork Xe Bang Fai Pumping - 35 -

5.13 Ban Na Than Dong Na Than Dong Xe Bang Fai Pumping - 30 -

5.14 Ban Na Khai Na Khai Xe Bang Fai Pumping - 30 -

VI Nongbok 4,275

3,527

80

6.1 Ban Na Tai Na Tai Xe Bang Fai Pumping 150 120 5

6.2 Ban Had Sieng Dy Had Sieng Dy Xe Bang Fai Pumping 250 200 5

6.3 Ban Sa Deu Neua Sa Deu Neua Xe Bang Fai Pumping 190 170 6

6.4 Ban Dong Sa Ngum Dong Sa Ngum Xe Bang Fai Pumping 90 80 2

6.5 Ban Ding Ka Sin Ding Ka Sin Xe Bang Fai Pumping 130 120 6

6.6 Ban Phon Sao Eh Phon Sao Eh Xe Bang Fai Pumping 100 90 4

6.7 Had Say Forng Had Say Forng Xe Bang Fai Pumping 200 150 4

6.8 Ban Na Vang Noi Na Vang Noi Xe Bang Fai Pumping 190 150 5

6.9 Ban Tan Theung Tan Theung Xe Bang Fai Pumping 350 250 5

6.10 Dong Phak Feua 1 Dong Phak Feua 2 Xe Bang Fai Pumping 150 140 3

6.11 Ban Sa Deu Tai Sa Deu Tai Xe Bang Fai Pumping 150 130 3

6.12 Ban Thaa Mouang Thaa Mouang Xe Bang Fai Pumping 90 82 3

6.13 Ban Nam Phooh 1 Nam Phooh 2 Xe Bang Fai Pumping 50 40 2

6.14 Ban Sam Na Dy Sam Na Dy Xe Bang Fai Pumping 80 70 2

6.15 Ban Nam Phooh 2 Nam Phooh 3 Xe Bang Fai Pumping 100 95 2

6.16 Ban Nong Sa Phang Nong Sa Phang Xe Bang Fai Pumping 120 100 2

6.17 Ban Na Man Pa Na Man Pa Xe Bang Fai Pumping 300 200 2

6.18 Ban Na Vang Thong Na Vang Thong Xe Bang Fai Pumping 180 160 2

6.19 Ban Na Vang Tai Na Vang Tai Xe Bang Fai Pumping 150 100 3

6.20 Ban Sork Bo Sork Bo Xe Bang Fai Pumping 350 300 2

6.21 Ban Na Vang Neua Na Vang Neua Xe Bang Fai Pumping 170 150 2


58

6.22 Ban Sieng Wang Sieng Wang Xe Bang Fai Pumping 350 300 2

6.23 Ban Beung San Thaa Beung San Thaa Xe Bang Fai Pumping 85 80 2

6.24 Dong Phak Feua 2 Dong Phak Feua 3 Xe Bang Fai Pumping 100 80 2

6.25 Dong Phak Phao Dong Phak Phao Xe Bang Fai Pumping 100 90 2

6.26 Ei Tou Ei Tou Xe Bang Fai Pumping 100 80 2

VII Hinboun 1,787 1,918 66

7.1 Don Dou Don Dou Hin Boun River Pumping 250 67 4

7.2 Pak Pa Kan Pak Pa Kan Pakan River Pumping 50 20 4

7.3 Hin Khan Hin Khan Hin Boun River Pumping 60 50 1

7.4 Poung Neua Poung Neua Mekong Pumping 150 100 3

7.5 Ban Phon Men Phon Men Hin Boun River Pumping 120 120 4

7.6 Ban Hinboun Tai Hinboun Tai Hin Boun River Pumping 70 55 4

7.7 Ban Hinboun Neua Hinboun Neua Hin Boun River Pumping 150 120 4

7.8 Ban Nong Hoi 1 Nong Hoi Pakan River Pumping 100 80 3

7.9 Ban Nong Hoi 2 Nong Hoi Pakan River Pumping 34 15 1

7.10 Ban Kham Keo 1 Kham Keo Hin Boun River Pumping 70 63 2

7.11 Ban Kham Keo 2 Kham Keo Hin Boun River Pumping 70 66 2

7.12 Ban Phon Kham Phon Kham Hin Boun River Pumping 100 80 -

7.13 Keng Phak Kham Keng Phak Kham Hin Boun River Pumping 24 20 3

7.14 Sa mak Khi Say Sa mak Khi Say Hin Boun River Pumping 20 20 3

7.15 Ban Tao Than Tao Than Hin Boun River Pumping 20 15 2

7.16 Ban Nong Boua Nong Boua Hin Boun River Pumping 49 40 4

7.17 Ban Vang Houa Pa Vang Houa Pa Hin Boun River Pumping 40 40 4

7.18 Ban Pounh Tai Pounh Tai Hin Boun River Pumping 88 60 3

7.19 Ban Don Lap Don Lap Hin Boun River Pumping 32 20 2

7.20 Ban Pha Vang Pha Vang Hin Boun River Pumping 30 25 6

7.21 Ban Nong Khoonh Nong Khoonh Hin Boun River Pumping 33 22 -

7.22 Ban Houay Khi Mi Noi Houay Khi Mi Noi Hin Boun River Pumping 44 10 -

7.23 Ban Na Neua Na Neua Hin Boun River Pumping 57 40 1

7.24 Ban Vang Khorngh Vang Khorngh Hin Boun River Pumping 60 40 6

7.25 Ban Vang Mon Vang Mon Pumping 36 30 -

7.26 Ban Pha Vang 2 Pha Vang Pumping 30 25 -

7.27 Korng Lor Kang Korng Lor Kang Pumping - 140 -

7.28 Tew Tew Pumping - 100 -

7.29 Na Kang Na Kang Pumping - 225 -

7.30 Phonyeng Phonyeng Pumping - 95 -

7.31 Yang Yang Pumping - 115 -

VIII Khamkeut 274 442 145

8.1 Nam Maheng NamKham Nam Maheng Dyke, gravity fed 35 40 15

8.2 Nam Gnok Nape Nam Gnok Dyke, gravity fed 20 30 20

8.3 Nam Thop-3 Nathone Nam Thop Dyke, gravity fed 25 35 15

8.4 Nam Khoua Thaveng Nam Khoua Dyke, gravity fed 15 40 5

8.5 Nam Khoua-1 Namkhoua Nam Khoua Dyke, gravity fed 12 25 8


59



8.8 HouayHoi Donexath Nam Khoua Dyke, gravity fed 16 20 6

8.9 Nam Mana Dongpang Nam Mana Dyke, gravity fed 50 17 30

8.10 Nam Phouane Khammouane Nam Phouane Dyke, gravity fed 5 50 -

8.11 Nam Thop-1 Nakadok Na Kadok Dyke, gravity fed 35 5 10

8.12 Nam Her Thongpe Thong pair Dyke, gravity fed 20 50 8

8.13 Nam Thop Gnoignhai Yoi Hai Dyke, gravity fed 20 40 12

8.14 Nam Kheio Phonetan Phontan Dyke, gravity fed - 50 -

IX Viengthong 22

5 28

1 57

9.1 Nam Khama Home Chaleun Nam Khama Dyke, gravity fed 20 30 5

9.2 Houay Zoo Sivilai Houy zoo Dyke, gravity fed 30 30 7

9.3 Houay Yang Na Pheun Houay Yang Dyke, gravity fed 30 30 10

9.4 Houay Pha Zune Cha Leun Mai Houay Pha Zune Dyke, gravity fed 20 40 5

9.5 Nam Zang Thorngmisai Nam Zang Dyke, gravity fed 25 40 10

9.6 Houay Zairh 1 Phondoo Houay Sair Gaboin Dyke - 31 -

9.7 Nam Yangh Nam Yangh Nam Yangh Gaboin Dyke - 30 -

9.8 Houay Say Nam Tak Nam Tak Dyke, gravity fed 100 50 20

basin profile of the nam theun/nam kading, nam hinboun … · this report covers the catchment of...

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