Environmental Assessment (EA)
Viet Nam Managing Natural Hazards Project (VN-Haz/WB5)
E2993 v3
ANNEX 3
Background on Key River Basins
1.
This annex provides environmental background in key river basins (Ma, Ca, Ha Vang-Rac, GianhNhat Le, Thach Han, Vu Gia - Thu Bon, Tra Khuc - Tra Bong, Kone, and Dinh). The data includes natural
features (climate, flow and flood, salinity intrusion), ecological features and cultural sites, water quality, and
socio-economic conditions. This information was used as the basis in assessing the potential impacts of the
Project.
A3.1. Environmental Background in Ma River Basin
A3.1.1. Natural features
2.
Ma River originates from the Northern side of Pu Huoi Long mountain range at an elevation of 2,179
meters (m) in Tuan Giao, Dien Bien province, continues in northwest – southeast direction across Son La,
Sam Nua (Lao PDR), Hoa Binh, Thanh Hoa, and discharges into the Pacific Ocean through the Sung, Lach
Truong and Cua Hoi tributaries. The Ma River basin system also includes three rivers, Chu River, Buoi River,
and Cau Chay River, all joining Ma River in Thanh Hoa Province in the Central Vietnam.
3.
Ma River is a 512 kilometers (km) long river, with a basin area being the fifth largest in Vietnam,
after Mekong River, Hong – Thai Binh River, Dong Nai River and Ca River. The total drainage area of the
basin is 28,400 square kilometers (km2), of which 17,720 km2 lies within Vietnam’s territory, making up 62%
of the total river basin area.
Climate
4.
The average temperature in the Ma River basin is relatively high throughout the year. The average
temperature recorded at the 14 meteorological stations within the Ma River basin varies spatially ranging
from 20.9-23.oC, reflecting the topographical characteristics and altitudes of the locations.
5.
Annual rainfall is substantial with dominant winds from south and southeast during May to
September months. The historical data recorded in the Ma River basin (1961-2007) show some special
variability in climatic conditions in annual rainfall of 1,165-1,966 millimeters (mm) with 80% of the rainfall
occurring during the monsoon (May to September) season. The average annual rainfall ranges from 1,200 to
1,700 mm per year (mm/year) in the upstream area, 1,500-1,600 mm/year in the middle stream area, 2,0002,200 mm/year in the upstream area of Chu River, and 1,600-1,800 mm/year in the lowland area. The rainy
season in the upstream areas begins in May and ends in October, while that in the Chu river basin is from late
August to early November.
6.
There are two factors that influence the wind characteristics in the Ma River basin: the southeast
winds in summer, originating from the Bay of Bengal, which increases the density of water vapor leading to
monsoon rains; and the presence of two parallel mountain ranges surrounding the Ma River basin that
partially blocks incoming air from the southwest in summer or from the north in winter. The average annual
wind speed in meters per second (m/s) in the Ma River basin indicates no big spatial variations in wind speed:
on an average, the lowest value corresponds to Tuan Giao (0.7 m/s) and the highest value to Moc Chau (2
m/s).
7.
The river flow varies greatly in time and space. In general, the distribution of flow of large and
medium rivers follows a one-peak pattern with the highest flow rate occurring in September or August.
However, the flow of small rivers in Chu river basin follows a two-peak pattern, with a second peak in May
or June. The river flow in cubic meters per second (m3/s) varies quite greatly in Cam Thuy. The average
discharge in April (111 m3/s) is only one-third of the annual discharge (334 m3/s) and one-seventh of the
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highest average discharge (in August). Data show that the highest discharges monitored at Cua Dai, Xuan
Khanh and Cam Thuy are 442 m3/s and 1,713 m3/s, respectively, and 258 times higher than the lowest
discharges at the same gauging station.
Flow and floods
8.
The flood season varies across the Ma River basin, from June to October across Ma River, from June
to November in the upper area of Chu river, and from July to November in the Chu River’s lowland area. The
total runoff in flood season accounts for 65-80% of the total annual runoff. Each year, Ma River’s total runoff
to the sea equals 18 billion m3/year. The flow is unevenly distributed.
9.
In the dry season, the runoff is only 4,76 billion m3, making up 26% of the total annual runoff.
Meanwhile, the 4 months of the flood season make up 74% of the total annual runoff. The driest period is
between February and April, which comprises 8% of the annual flow. March tends to have the lowest flow
rates, contributing only 2.4% of the total.
The total runoff per person in the Ma river basin is over 4,100 m3/person, only slightly higher than the
standard (4,000 m3/year), however, this number will be considerably reduced if the flows coming from
outside the country (22% of the runoff) are excluded, and the average total water supply per person goes
down to only 1,080 m3/person.
Salinity intrusion
10.
Salinity intrusion is influenced by tides and river flows. In the dry season, the salinity intrusion in the
downstream part of Len River can extend up to 20-25 km from the river mouth. Salt water intrusion reaches
Yen On along Len River, Mi Quang Trang along Can River and Tuan T-junction along Ma River. The entire
Lach Truong River always saline in the dry season. On Ma River, at Ham Rong, the salinity rises up to 6 %o
in 2-3 hours when the tides peak, up to 0.1%o half tide at Tuan T-junction. On Len River, the salinity is at
0.1%o. The intrusion even reaches Bao Van in several years. The salinity intrusion in Lach Truong River
often reaches Xiphong Cu Da in the dry season.
A3.1.2. Ecological features and cultural sites
11.
Ma River basin’s ecosystem is characterized by both Northwest and North-Central ecosystems.
Evergreen forests are the typical type of natural forests of the basin. There are 7 conservation areas within the
river basin: i) Pu Hu Nature Reserve (35,089 ha); ii) Pu Luong Nature Reserve (17,662 ha); iii) Ben En
National Park (16,634 ha); iv) Xuan Liem Natural Reserve (23.61 ha); v) Xuan Nha (38,069 ha); vi) Pa CoHang Kia (7,091 ha); vii) Cuc Phuong National Park (22,200 ha). Conversation area index is estimated at
5.66%, which is of low-medium level compared to other basins. The index indicates that the conservation
value and environmental assets in the basin are at low-medium level.
12.
Basin forest cover rate is estimated 44% at medium level, compared to other basins. The rate
indicates important role for sustaining river basin processes. Basin native forest rate is high 77.3% that
indicates good forest quality and good catchment processes for runoff and water quality. However, it is
generally acknowledged that the quality of natural forests continues to be more fragmented and degraded.
Most of the natural forests are considered poor or under recovery; significant forest fragments remaining are
mostly in Nature Reserves, National Parks.
13.
There are 4 Historical/Cultural Sites approved by The Government in the Basin. Heritage Index of
Ma basin is of medium level.
Table A3.1: Ecological features of Ma river basin
Total area: 28,400 km2 of which 17,720 km2 are located in Vietnam
Environmental health: Biodiversity and ecosystems
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Characteristics
Included: terrestrial and aquatic ecosystems
 Ma river basin’s ecosystem is characterized by both Northwest and North-Central
ecosystems. Evergreen forests are the typical type of natural forests of the basin;
lowland evergreen forests now only remain in some areas of Ben En National Park
Conservation
areas
There are 4 Conservation areas, including National Parks, Nature Reserves recognized by
The Government in the Basin
 Conversation area index is estimated at 5.66%, which is of low-medium level compared
to other basins. The index indicates that the conservation value and environmental assets
in the basin are at low-medium level
Historical/
Cultural Site


Major water
related
environmental
assets
1. Sop Cop Nature Reserve
Location, area, water source
Area: 27,886 ha
 Sop Cop Nature Reserve is located in Song Ma district in the mountainous north-west of
Vietnam. The topography of the nature reserve is steep and mountainous, and elevations
range from 450 to 1,940 m. The nature reserve is fed and drained by tributaries of the
Ma river.
 The natural vegetation has been extensively cleared and replaced by scrub. However, it
appears that areas of evergreen forest still remain at high elevations.
 The fauna was previously very rich, and the site supported a high diversity and
abundance of large mammal species, including, in the 1950s, a species of rhinoceros.
However, faunal diversity at the site has decreased in recent years.
 Forest at Sop Cop Nature Reserve protects the catchments of streams that provide local
communities with water for irrigation and domestic use.
There are 4 Historical/Cultural Sites approved by The Government in the Basin
Heritage Index of Ma basin is of medium level (4), compared to other basins.
2. Ben En National Park
Location, area, water source
Area: 16,634 ha
 Ben En National Park is located in Nhu Thanh and Nhu Xuan districts, Thanh Hoa
province. The national park is situated in a region of low hills surrounding an artificial
lake. Altitude ranges from 20 to 497 m, with most areas being below 200 m. The lake is
50 m above sea level and covers 2,281 ha. The geology of the national park is
characterized by sedimentary rocks, particularly mudstone. Small areas of limestone are
also present, and impressive limestone karts formations can be found in the buffer zone
in north-east boundary of the national park.
 The core zone of the national park is fed and drained by the Muc river, while the
proposed extension to the national park is fed and drained by the Chang river
 Ben En National Park is moderately important for the conservation of biodiversity. The
national park protects one of the few surviving areas of lowland evergreen forest in
north-central Vietnam. The forest has, however, been extensively disturbed in the past
by commercial logging operations, and, as a result, is characterized by small, shadeintolerant trees and a dense undergrowth dominated by bamboo. However, since the
cessation of commercial logging, forest quality has improved
 There are 870 species of high plant, 375 species of fauna, including amphibian, reptile,
mammal and bird (1998), in which a number of globally threatened trees and mammals
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have been recorded at the national park





Physical
condition
Land use
Proportions
Vegetation
cover



Forest cover: 44%
Agricultural cover: 20%
Resident cover 3%
Specific use 4%
Other use 29%
Vegetation Index of Ma River Basin occupies 6.18% of total national forest area. –
Lower than other basins. This basin take a less important role to meeting the national
forest target
Basin forest cover rate is estimated 44 % at medium level, compared to other basins.
The rate indicates important role for sustaining river basin processes
Basin native forest rate is high 77.3% that indicates good forest quality and good
catchment processes for runoff and water quality. However, it is generally
acknowledged that the quality of natural forests continues to be more fragmented and
degraded. Most of the natural forests are considered poor or under recovery; significant
forest fragments remaining are mostly in Nature Reserves, National Parks
A3.1.3. Water quality
14.
According to the annual Environmental Reports of Thanh Hoa province in the past few years, the water
quality of four rivers – Ma river, Len river, Cau Tao river and Chu river – within Ma river basin is generally
good. Water quality analysis performed at the 20 monitoring locations on these rivers show no signs of
contamination by heavy metals, for example, with the content of Cd and As ranging from below 0.001 mg/l0.002 mg/l and below 0.001 mg/l-0.01 mg/l, respectively, which are below the national standard (QCVN
08:2008/BTNMT). However, at some monitoring locations, the BOD value, varying between 2.3 mg/l-8.9 mg/l,
has exceeded the permissible limit for Grade A water (4-6 mg/l), but still very low compared to the standards for
Grade B water (15-25 mg/l). The COD value, in the orders of 3.2 mg/l-12.5 mg/l, is below the permissible limit
for Grade A water (10-15 mg/l) according to QCVN 08:2008/BTNMT. Based on evaluation, the surface water
in Ma river basin has shown signs of light pollution from organic substances in some river sections passing
through residential and industrial areas.
Table A3.2: Surface water quality parameters in Ma river basin
Monitoring location
Na Sài
Cửa Hà, Cẩm Thủy
Cầu Kiểu
Cầu Vạn Hà
Ngã ba Bông
Làng Giàng
Cầu Hoàng Long
Cảng Lễ Môn
Cửa Hới
Cầu Tào
Cầu phao Bút Sơn
Gũ - Nga Sơn
Monitoring parameters
COD
(mg/l)
3,5
4,5
5,9
6,8
3,2
6,3
4,9
8,5
7,8
8,6
9,8
BOD
(mg/l)
2,4
3,2
4,2
4,9
2,3
4,8
3,8
6,2
5,6
5,9
7,3
NO3(mg/l)
0,78
<0,01
1,36
<0,01
0,68
0,9
<0,01
6,2
5,8
1,82
1,45
SS
(mg/l)
156
150
250
110
148
380
320
5520
25.640
1440
1630
Cd
(mg/l)
<0,001
<0,001
0,001
<0,001
0,001
0,001
0,001
0,002
0,001
0,001
<0,001
As
(mg/l)
<0,001
<0,01
<0,01
<0,01
<0,01
<0,01
<0,01
<0,01
<0,01
<0,01
<0,01
Coliform
(MPN/ml)
150
150
130
210
130
220
240
480
120
180
150
4,8
3,4
0,12
169
<0,001
<0,01
170
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Monitoring location
Đò Thắm
Đập Bái Thượng
Dưới cửa xả KCN Mục Sơn
Dưới XN giấy QĐ
Giáp ngã ba Bông
Trên cửa xả KCN Mục Sơn
Cầu Mục Sơn
Thị trấn Thọ Xuân
Monitoring parameters
COD
(mg/l)
9,2
4,5
4,5
12,5
6,4
9,4
8,5
5,8
BOD
(mg/l)
6,4
3,2
3,1
8,9
4,3
6,4
6,9
3,6
NO3(mg/l)
1,12
<0,01
<0,01
2,25
0,01
1,78
3,6
0,68
SS
(mg/l)
1970
105
118
380
240
322
250
145
Cd
(mg/l)
0,001
<0,001
<0,001
0,001
0,001
<0,001
0,001
0,001
As
(mg/l)
<0,01
<0,01
<0,01
<0,01
<0,01
0,01
<0,01
<0,01
Coliform
(MPN/ml)
110
120
120
720
160
690
190
130
A3.1.4. Socio-economic conditions
Economic conditions
15.
Thanh Hoa accounts for most of the area of this river basin. GDP accounts for 2.83% of the national
GDP. Its economic structure is: agriculture 35%, industry 32% and service 33%. For the last 5 years, its
annual GDP growth is 10.1%. The area of agriculture and cultivation land is insignificant, of which, paddy
area makes up 65%. The yearly paddy production is low. Livestock output only accounts for 25% of the
agriculture sector’s GDP. Forestry land makes up 75% of the province’s area, the production value, however,
is not high. Aquaculture, mainly cultivation on the coastal area and catching on the rivers, is developing fast.
Industry is of slow development. The main industries are sugarcane and material manufacturing. Nghi Son
Cement Factory and Nghi Son Industrial Park are the two major industrial units in the province. Tourism and
commerce are also of slow growth and small scale. Sam Son is the main tourism spot.
Social conditions
–
Population: Up to 2006, the population of Ma river basin is 4382.6 thousand, making for 5.21% of
the whole country’s total population. The average population density is 247 people/km2. The average
population growth rate of the basin is 1.11%.
–
Ethnicity: The ethnic minorities account for 25.55%, of which, 14.4% is in Thanh Hoa and 13.25% in
Nghe An. Ethnic minorities live mainly in rural and remote areas and on self-sufficient agriculture.
–
Poverty rate: The average poverty rate of the basin is up to 53.8%, and virtually three times higher
than the average poverty rate of the whole country. In the basin, the highest poverty rate is of Nghe
An: 40.8% (of which, poverty rate of Que Phong district amounts to 83.41%) and the third is Thanh
Hoa: 35.65%.
–
Employment: Emloyment concentrates mostly in the agriculture sector. Industry and service sectors
are underdeveloped. The most developed industry is in Thanh Hoa and concentrates mainly in the
urban area: Thanh Hoa City.
A3.2. Environmental Background in Ca River Basin
A3.2.1. Natural features
16.
Ca river is an international river and Ca river basin is a large river basin in Vietnam. The river lies
between latitude 18015’00’’ and 20010’30’’ North and between longitudes 103045’20’’ and 105015’20’’ East.
The main flow of Ca river originates from Muong Khut, Muong Lap in Lao PDR, at over 1800-2000m height,
it continues in northwest – southeast direction, enters Nghe An at Keng Du and flows into the sea through Hoi
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river mouth. In the upstream, the river bed is narrow and steep, with many falls, while in the midstream (from
Con Cuong to Anh Son), the river bed expands and receives Hieu river from the left bank; the downstream
section flows through the plain area, receives La river from the right bank and then flows into the sea through
Cua Hoi. The total basin area is 29,930 km2, including 20,460 km2 in Vietnam’s territory.
Climate
17.
The average rainfall in the river basin is around 1,700-1,800 mm/year. Several locations with high
rainfall reach 2,200 mm/year in La river basin, 2,000-4,000 mm/year in Giang river basin. In the dry season,
the rainfall makes up only 35% while 4 months of the rainy season make up 65% of the total annual rainfall.
Flow and floods
18.
The river flow is determined by rainfall and typographic conditions of the river basin. Low flow rate in
Ca river (at Yen Thuong) lasts for 7 months (December – June), while the high flow rate lasts for 5 months in
a year (July – November). At Yen Thuong, the lowest average monthly flow rate is approximately ¼ of the
average annual flow rate and 1/10 the highest average monthly flow rate. The total annual runoff of Ca river
is 23.5 billion m3, of which 20.5 billion m3 (87%) is originated in the territory of Vietnam. The rest 3.0 billion
m3 (13%) is originated from Laos. The average annual water availability per capita in Ca river basin is 6,050
m3/person/year, 1,5 times as much as the standard set by the International Meteorological Organization (4,000
m3/person/year). In the dry season, this figure is 1.760 m3/person/year.
19.
In the basin, there are 2 flood periods, May rain-flood period in May – June, and main flood season in
September – November. The main flood season starts and ends at different time on different river branches.
Towards the main flow, floods start from June to October or November. Towards La river, floods start in
August and end in December. Floods on Lam river last from June to December. Floods on Ca river branches
never occur at the same time, especially big floods. Double floods often occur on branches of Hieu river and
Ca river, while single floods often occur on Giang river and La river.
Salinity intrusion
20.
According to monitoring figures of the month April in several years from the Institution of Water
Resources Planning, salinity limit of 10/00 reaches Duc Xa sluice on La river and it reaches Yen Xuan bridge
on Ca river. The salinity limit in the tidal areas depends on the discharge from the upstream and wind
direction at the river mouth. If the discharge at Yen Thuong reaches 150-180 m3/s, the salinity of 10/10 only
appears in 2-3 hours at Duc Xa, Cho Chang, and 6-8 hours at Trung Luong. But if the discharge at Yen
Thuong is below 100 m3/s, the salinity of 10/00 appears in 3 hours at Yen Xuan, 6 hours at Cho Chang, and
12 hours at Trung Luong. This indicated that the supplement for upstream discharge to push out the salinity is
necessary.
A3.2.2. Ecological features and cultural sites
21.
Ca river basin’s ecosystem is characterized by North-Centre ecosystems. Lowland and lower
mountains evergreen forest is the typical type of natural forests in the basin. There are 3 Conservation areas,
including National Parks, Nature Reserves approved by The Government in the Basin. i) Pu Mat National
Park (91,113 ha); ii) Vu Quang National Park (55,029 ha); iii) Pu Mat National Park (46,600 ha).
Conversation area index is estimated at 10.78%, which is at high-medium level, compared to other basins.
The index indicates the conservation value and environmental assets in the basin are at high-medium level.
22.
Basin forest cover rate is estimated 40 % at medium level, compared to other basins. The rate
indicates important role for sustaining river basin processes. Basin native forest rate is high 76.3% which
indicates good forest quality and good catchment processes for runoff and water quality. In addition, nature
forest is still good because primary forest area is still high.
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23.
There is 1 Historical/Cultural Site approved by The Government in the Basin. Heritage Index of Ca
basin is low.
Table A3.3: Ecological features of Ca river basin
Total area: 29,930 km2 of which 20,460 km2 are located in Vietnam
Environmental health: Biodiversity andecosystems
Characteristics
Included: terrestrial and aquatic ecosystems


Conservation
areas

Ca river basin’s ecosystem is characterized by North-Centre ecosystems. Lowland and
lower mountains evergreen forest is the typical type of natural forests in the basin;
The basin is in North Central Region, a typical feature of the region is the long but
narrow strip of land between the Annamite Range and the sea. Rich forests still cover a
long strip of the Annamite Range, near the Lao border.

There are 3 Conservation areas, including National Parks, Nature Reserves approved by
The Government in the Basin
Conversation area index is estimated at 10.78%, which is at high-medium level,
compared to other basins. The index indicates the conservation value and environmental
assets in the basin are at high-medium level
Historical/
Cultural Site


There are 1 Historical/Cultural Sites approved by The Government in the Basin
Heritage Index of Ca basin is low (1), compared to other basins.
Major water
related
environmental
assets
1. Pu Mat National Park
Location, area, water source
Area: 91,113 ha
 Pu Mat National Park is situated in the northern Annamite Range. Elevations at the
national park range between 100 and 1,841 m, although 90% of the national park is
under 1,000 m in elevation.
 The national park is fed and drained by four main rivers: the Khe Thoi, Khe Bu, Khe
Choang and Khe Khang. All four rivers feed the Ca river, which runs from west to east,
through a wide valley to the north of the national park.
 Forest at Pu Mat National Park protects the catchments of four rivers, which,
collectively, are the main source of water for irrigation and domestic use for
communities in the buffer zone. In addition, the forest at Pu Mat protects part of the
watershed of the Ca river, the major river in southern Nghe An province.
 There are 2469 species of plant, 938 species of fauna (120 species of mammal, 295
species of bird..) Especially, Pu Mat is probably one of the most important sites for
mammal conservation in Vietnam (discovered Sao La Pseudoryx nghetinhensis); 37
mammal species are listed in Global and Vietnamese Red Book.
 Pu Mat National Park preserves one of the best examples of the Annamite mountains
ecosystem, and is of international conservation significance. The national park supports
one of the largest remaining blocks of natural forest in northern Vietnam, and is linked
to other protected areas in Vietnam and Laos by contiguous areas of forest.
2. Vu Quang National Park
Location, area, water source
Area: 55,029 ha
 Vu Quang National Park is located in Huong Son and Huong Khe districts, Ha Tinh
province and is situated in the northern Annamite mountains. The national park contains
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
an elevation gradient of over 2,000 m, from 30 m in the lowlands in the north-east of the
national park to 2,286 m at the summit of Mount Rao Co, on the border with Laos.
The National Park is fed by three rivers: the Nam Truoi, Rao No and Khe Tre rivers.
These rivers originate in the south of the national park, as steep, narrow, fast-flowing
streams
There are 465 species of high plant and 70 species of mammal, 273 species of bird, in
which a number species are rare and valuable ones
The Site to be considered to be of the highest regional importance for bird conservation
Physical
condition
Land use
Proportions





Forest cover: 40%
Agricultural cover: 19%
Resident cover 1%
Specific use 4%
Other use 27%
Vegetation
cover

Vegetation Index of Ca River Basin occupies 6.45% of total national forest area. –
Lower than other basins. This basin take a less important role to meeting the national
forest target
Basin forest cover rate is estimated 40 % at medium level, compared to other basins.
The rate indicates important role for sustaining river basin processes
Basin native forest rate is high 76.3% which indicates good forest quality and good
catchment processes for runoff and water quality. In addition, nature forest is still good
because primary forest area is still high.




A3.2.3. Water quality
24.
Monitoring results of Ha Tinh and Nghe An provinces in recent years show that, at monitoring
locations on Quyen, La, Lam rivers and Cua Tien dug river, signs of water pollution from heavy metals such
as Cd, Pb haven’t been discovered. However, the BOD value at those monitoring locations has exceeded
permissible limits of QCVN for Grade A water, although still within limit for Grade B water. Coliform value
has exceeded QCVN for Grade B water at some locations such as Tay Yen bridge (Ky Anh district, Ha Tinh
province) and Duoc brigde (Nghe An).
Table A3.4: Water quality parameters in Ca river basin
No.
Parameters
1
2
3
4
5
6
7
8
9
10
COD (mg/l)
BOD (mg/l)
DO (mg/l)
NH4+ (mg/l)
NO3- (mg/l)
PO43- (mg/l)
SS (mg/l)
Pb (mg/l)
Cd (mg/l)
Coliform
(MPN/ml)
Quyền river (Tây
Yên Bridge, Kỳ Anh,
Ha Tinh)
28,7
18,4
5,6
0,54
29
12.600
La river (Thọ Tường
bridge, Đức Thọ, Ha
Tinh)
22
17,2
6,3
0,41
37
580
Lam river (Ben
Thuy bridge,
Nghe An)
10,1
5,7
5,03
0,41
3,66
0,04
34
KPH
KPHK
700
Cửa Tiền dug river
(Đước bridge,
Nghe An)
12,2
6,58
4,58
0,39
4,06
0,12
42
KPH
KPH
11000
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A3.2.4. Socio-economic conditions
Economic conditions
25.
Ca river basin basically consists of Nghe An and Ha Tinh. GDP of this basin accounts for 2.97% of
the national GDP. The economic structure is: agriculture 38%, industry 26% and service 36%. The average
annual GDP growth rate for the past 5 years is 9.8%.
–
Agriculture: the average rice yield is 40 tons/ha (2002). Livestock mainly focuses on small-scale
breeding of animals and pigs of households.
–
Industry: some industries have recently been formed such as cement, sugarcane and steel. Vung Ang
Industrial Park has great potential for economic development.
–
Aquaculture: face a good deal of difficulties regarding water sources.
–
Tourism and trade: small-scale and slowly developing.
Social conditions
26.
Population: The basin’s population scale is 3883.5 thousand people, making up 4.6% of the national
population. The Ca river basin’s population includes all the population of Nghe An except for 50% Que
Phong district’s population (belong to Ma river) which accounts for 78% of the total population of the basin.
Then comes Ha Tinh: 20% (except for Thach Ha, Cam Xuyen and Ky Anh district). Thanh Hoa only accounts
for 2% - which is half of the population of Nhu Xuan district. The average population growth rate is nearly
1.3%. About 20% of the population is in city and urban area while 30% is in the highlands and high
mountainous area. The average population density of the basin is 190 people/km2 while the delta’s population
density is 453 people/km2. The population density of Nghe An is 186 people/km2 and Ha Tinh is 217
people/km2. The average population growth rate of the basin is 0.88%. It shows that people in the basin
continues to emigrate to other regions in the recent years.
27.
Ethnicity: 9.58% of the basin’s population is ethnic minority, living mainly in the mountainous and
remote districts of 3 provinces – Thanh Hoa, Nghe An and Ha Tinh - especially Thanh Hoa. Ethnic
composition consists of Chut, Muong, Thai, Tay and Nung, etc.
28.
Poverty rate: Poor households of this basin accounts for up to 47%, rank third after Ma river and
Srepok river. The highest poverty rate is of Tuong Duong district (Nghe An): 96%, followed by Ky Son
commune: 93%, which is 4.5% times higher than the general poverty rate of the whole country.
A3.3 Ha Vang river and Rac river basin (Ha Tinh)
29.
The entire Ha Vang and Rac river basin is in the area of Ha Tinh province. Ha Vang is a small river in
Ha Tinh province. It rises from Ho Do bridge, Ho Do commune, Thach Ha district, which is the crossover of
Nghen river and Ho Do river. From this position, the river runs to the North-eastern direction and pours into
the Eastern Sea through the Sot estuary under Thach Kim commune, Thach Ha district. The river has the
length of relatively 12 km and wide river bed, the widest is about 2 km which is the solely waterway from Ha
Tinh city to the Eastern Sea. See Figure A2.3 (Annex 2) for Ha Vang – Rac river basin map.
30.
This basin has the climate condition of the North Ngang pass of North Central coastal region. Each year, it
is heavily affected by the North-east monsoon. This region’s main characteristic is cold winter and dry and hot
summer. The North-east monsoon blows from June, July to April of the following year. The region’s rainy season
begins in August and ends in November of the following year. As for period of time, the rainfall usually
concentrates in September, October and November. In these 3 months, rainfall accounts for nearly 70% of the total
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yearly rainfall, but September and October’s proportion amounts to 69% of the total rainfall of the above three
months. Spatially, rainfall tends to gradually increase from the North to South.
A3.4 Gianh and Nhat Le river basins (Quang Binh)
31.
Gianh river basin has the natural area of 4,680 km2, including Ron river, Gianh river, Ly Hoa river
and Dinh river in the vicinity of four districts - Quang Trach, Bo Trach, Minh Hoa and Tuyen Hoa - of Quang
Binh province and six communes of Ky Anh district, Ha Tinh province. The research area is limited to: the
North borders with Rac river basin , Rao Cai river, Ngan Sau river of Ha Tinh province; the South borders
with Nhat Le river basin of Quang Binh province; the West with Laos and the East with the Eastern Sea .
32.
The Nhat Le River is a river in Dong Hoi, Quang Binh province. The Nhat Le River is 152 km long,
of which the Kien Giang river is 58 km in length, and the Long Dai river is 77 km long. The river is formed
by the confluence of the Kien Giang river in Le Thuy district and the Long Dai river in Quang Ninh district.
The Nhat Le River flows northeast (unlike most rivers in Vietnam, which run southeast) before emptying into
the South China sea. At the mouth of this river are several white fine sand beaches which are popular tourist
attractions.
33.
Gianh and Nhat Le river basins terrain are narrow and steep from the West to East. Hills and
mountains account for 85% of the total natural area. Its topography is diverse. The West of the province is
mountainous area of the height from 1,000-1,500 m, next to it is low hill area, scattered in an upside down
bowl shape. There is a small and narrow strip of plain near the coast line. Last are coastal strips of sand with
the shape of sickle.
34.
Dry season is from April to August. Rainy season is from September to March of the following year,
flood season in the western slope of the Truong Son is from July to October and the high season is usually
from September to December. The average annual rainfall is from 2000 – 2,300 mm.
35.
Gianh and Nhat Le river basins’ ecosystem is characterized by the limestone forest ecosystem. There
are only one Conservation area, that is Phong Nha-Ke Bang National Park (85,754 ha), that approved by The
Government in the Basin. Conversation area index is estimated 18.32% is high level, compared to other
basins. The index indicates the conservation value and environmental assets in the basin is high level.
36.
There are no Historical/Cultural Sites in the Basin. It indicates there are insignificant heritage/
cultural and historic assets in the basin.
A3.5 Thach Han river basin (Quang Tri)
37.
Thach Han river basin is 155 km in length; the largest valley area is 2,660 km2. The main river
branch is Thach Han which is derived from the big mountains of Dong Sa Mui, Dong Voi Mep (Rao Quan
branch) and Ba Le cavern, Dang cavern (Dakrong branch). Thach Han river pour into the sea through Viet
estuary. The map of Thach Han river basin - Ben Hai is presented in Figure A2.5 (Annex 2).
38.
The rainy season occurs from September to January of the following year, the rainfall is about 75-85% of
the total yearly rainfall. There are usually heavy and prolonged rains from September to November (approximately
600 mm). The months with the least rainfall are February and July (40 mm/month for the least). The total annual
rainfall ranging from 2,000-2,700 mm, the number of rainy days is 130-180. The stormy season in Quang Tri
occurs from July to November, of which, September and October have the most storms.
38.
Thach Han river basin’s ecosystem is characterized by the tropical closed forest. There are no conservation
area in the basin. It indicates the conservation value and environmental assets in the basin is very low.
39.
There are one Historical/Cultural Sites in the Basin that is Thanh Co Quang Tri. It indicates there are
less significant heritage/ cultural and historic assets in the basin.
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A3.6. Environmental Background in Vu Gia - Thu Bon River Basin
A3.6.1. Natural features
40.
Vu Gia – Thu Bon river basin is one of the largest basin in the Central Coast, located on the Eastern
side of the Annamite Range. The basin lies between latitudes 16055' and 14055’ North, and longitudes 107015'
and 108024' East. The dominant direction of slope of the basin is northwest – southeast, with an average
gradient of 25,5%. The upstream area is high mountains of 1,700-2,045m height, which form an arc around the
entire northern, western and southern parts of the basin. The downstream area is the coastal lowlands. The total
basin area is 10,350 km2, including 560.5 in Kon Tum, the rest loes mainly within Quang Nam province and
Da Nang city. Vu Gia – Thu Bon river basin lies within the tropical monsoon area, deeply influenced by
typographic elements, therefore, the area has an unusual climate.
Climate
41.
The average annual rainfall ranges from 2,000 to 4,000 mm/year and decreases from the mountains to
the lowlands. Mountain sides facing winds have significantly high rainfall, in contrast, the sides hidden from
the winds received much lower rainfall. In the lowlands, the annual rainfall is around 2,000 mm, such as in
Da Nang (2,051 mm), Hội An (2,058 mm), meanwhile rainfall in the mountainous areas are higher, such as in
Bà Nà (2,341 mm), Nông Sơn (2,634 mm), especially in high mountains such as Thu Bon upstream area,
where the typography facing the winds has formed places of high rainfall such as Trà My (3,738 mm/year),
Tiên Phước (2,833 mm/year).
42.
The dry season lasts for 8 month from January to August, when rainfall makes up only 20-35% of the
total annual rainfall. February, March and April are months with lowest rainfall, at only 10-30 mm in the
lowlands and 30-100 mm in the mountains.
43.
The rainy season, when northeast monsoon winds prevail in the basin, begins in September and ends in
December, later than the North and the South regions. In the rainy season, the rainfall accounts for 65-80% of
the total annual rainfall. Months with highest rainfall are October and November, making up 40-50% of the total
annual rainfall.
Flow and floods
44.
The flow in the river basin is divided into two separate seasons (flood season and dry season). The flow
variations in Vu Gia – Thu Bon river basin are quite complicated, the annual flow in high flow years can be 4 to
8.25 times higher than that in low flow years. Because of the seasonal characteristic, the distribution of flow is
uneven in different months in the year, with big difference between high season month and low season month.
45.
The lowest discharge is in April or August. The runoff in the dry season makes up 21.8-38.5% of the
total annual runoff. The month with the lowest runoff is April, making up only 2.1-2.6% of the total annual
runoff. Area with the highest discharge in the dry season is the upstream Thu Bon river, area with the lowest
discharges are the North and Northwest of the basin. The dry season is divided into two periods:
46.
Floods in Vu Gia – Thu Bon river basin are big and rapid due to the steep typography and high
rainfall. The flood season often begins in mid-September and ends in early January in the next year. The flood
season often begins and ends from half a month to a month earlier than the rainy season. The start and ending
time of flood season and biggest floods are quite similar in Quang Nam province and Da Nang city. The
runoff in flood season makes up 62.5-69.2% of the total annual runoff. However, the flood time is not stable,
in many years, floods can happen from September to January of the next year. The highest flood discharge
monitored is 10,600 m3/s (4/12/1999) in Nong Son and Thành Mỹ 7,000 m3/s (20/11/1998).
Salinity intrusion
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47.
The salinity intrusion in the rivers follows two cycles, corresponding with two high tide cycles, during
which the saline water intrudes deeply in the rivers. During the low tides, deep salinity intrusion is less possible.
A3.6.2. Ecological features and cultural sites
48.
Ecosystem of Vu Gia-Thu Bon river’s downstream: characterized by magrove forest ecosystems like
coral reefs, seagrass beds and coastal lagoons, including wetlands with area of 500 ha in Cam Thanh, Cam
Kim Communes and surrounding areas-Hoi An Town-Quang Nam Province. There are 3 Conservation areas,
including National Parks, Nature Reserves approved by The Government in the Basin, which are Ba Na-Nui
Chua National Park (Area: 38,210 ha). Conversation area index is estimated 3.84% which is at low-medium
level, compared to other basins. The index indicates the conservation value and environmental assets in the
basin are at low-medium level.
49.
Basin forest cover rate is estimated at 49 % which is at medium level, compared to other basins. The
rate indicates the important role of the forest cover to the sustainable growth of the river basin. Basin native
forest rate is high 87% which indicates good forest quality and good catchment processes for runoff and water
quality. In addition, nature forest is still good because the primary forest area is still high.
50.
There are three Historical/Cultural Sites approved by The Government in the Basin, that are Hoi An
Ancient town, Ngu Hanh Son and My Son Holy Land, in which The ancient town of Hoi An and the My Son
Cham Holy Lands are two old cultural sites which are in the process of applying to the UNESCO for
recognition as World Cultural Heritage.
Table A3.5: Ecological features of Vu Gia – Thu Bon
Total area: 10,350 km2 of which 10,350 km2 are located in Vietnam
Environmental health: Biodiversity andecosystems
Characteristics
Included: terrestrial and aquatic and wetland/mangrove ecosystems
 Lowland and lower mountain evergreen forests are the typical type of natural forest
ecosystem of Vu Gia-Thu Bon river basin;
 Ecosystem of Vu Gia-Thu Bon river’s downstream: characterized by magrove forest
ecosystems like coral reefs, seagrass beds and coastal lagoons, including wetlands with
area of 500 ha in Cam Thanh, Cam Kim Communes and surrounding areas-Hoi An
Town-Quang Nam Province
Conservation
areas


Historical/
Cultural Site


Major water
related
environmental
assets
There are 3 Conservation areas, including National Parks, Nature Reserves approved by
The Government in the Basin, which are Ba Na-Nui Chua National Park and Cu Lao
Cham Nature Reserve
Conversation area index is estimated 3.84% which is at low-medium level, compared to
other basins. The index indicates the conservation value and environmental assets in the
basin are at low-medium level
There are three Historical/Cultural Sites approved by The Government in the Basin, that
are Hoi An Ancient town, Ngu Hanh Son and My Son Holy Land, in which The ancient
town of Hoi An and the My Son Cham Holy Lands are two old cultural sites which are
in the process of applying to the UNESCO for recognition as World Cultural Heritage.
Heritage Index of Vu Gia-Thu Bon basin is high (3), higher than other basins.
1. Ba Na-Nui Chua National Park
Location, area, water source
Area: 38,210 ha
 Ba Na-Nui Chua Nature Reserve centred on Mount Ba Na, a 1,487 metre - high
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



Physical
condition
Land use
Proportions
Vegetation
cover
mountain on the border between Da Nang city and Quang Nam province. The National
Park located in Hoa Ninh Commune-Hoa Vang District, west 38 km to Da Nang City
North-West part of the national park is fed and drained by streams - tributaries of Yen
river, which flows to downstream of Vu Gia, then flows into the south of the Da Nang
bay. South-East part of the National Park is fed anddrained by tributaries of Cu De river,
which flows into the north of the bay
543 species of vascular plants have been recorded at Ba Na-Nui Chua Nature Reserve.
These include 12 species listed in the Red Data Book of Vietnam
According to the investment plan, 61 mammal species, 178 bird species and 17 reptile
species have been recorded at Ba Na-Nui Chua. (1994). Many of the species listed in the
investment plan were also recorded during surveys by Frontier-Vietnam in 1994 and
1995, which recorded 472 vascular plant species, 29 mammal species, 106 bird species,
20 reptile species, six amphibian species, 33 fish species and 126 butterfly species.
These include 44 rare and valuable fauna species listed in the Red Data Book of
Vietnam
The forest at Ba Na-Nui Chua Nature Reserve protects the watersheds of the Ca De and
Yen rivers. These rivers are an important source of water for irrigation, and domestic
and industrial use in Da Nang city.





Forest cover: 49%
Agricultural cover: 12%
Resident cover 3%
Specific use 3%
Other use 33%

Vegetation Index of Vu Gia-Thu Bon River Basin occupies 4.04% of total national
forest area, lower than other basins. This basin takes a less important role to meeting the
national forest target
Basin forest cover rate is estimated at 49 % which is at medium level, compared to other
basins. The rate indicates the important role of the forest cover to the sustainable growth
of the river basin
Basin native forest rate is high 87% which indicates good forest quality and good
catchment processes for runoff and water quality. In addition, nature forest is still good
because the primary forest area is still high.


A3.6.3. Water quality
51.
Based on the surface water monitoring results through the years in Quang Nam province, some
conclusions can be drawn out as follow: Most of the parameters of water in Tiên, Tranh, Ly Ly, Bến Giằng,
Vu Gia – Thu Bồn rivers and Phú Ninh reservoirs are within the permissible limits, except the SS content in
Tien and Tranh rivers which is 1.35 – 2.46 times higher than the limit. In short, the quality of surface water in
most of the rivers and reservoirs in Quang Nam province is relatively good, except for Vinh Dien anh Truong
Giang rivers, signs of pollution from TSS, BOD5, COD have been discovered and tend to increase.
52.
Results from the Vu Gia river water quality monitoring program carried out by Da Nang DONRE in
recent years show that most of the parameters are within permissible limits, except Coliform value exceeding
Grade A limit by many times at all monitoring location. Overall, contents of pollutants in the river water such
as BOD5, COD, SS, heavy metals such as Fe, Pb have reduced over the years. The Hg content in water,
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Environmental Assessment (EA)
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although still within QCVN limit, is much higher than in previous years. Water quality in Vu Gia river within
Danang city has been improved compared to previous years.
A3.6.4. Socio-economic conditions
Economic conditions
53.
This basin consists of Quang Nam province and part of Da Nang and Kon Tum. GDP accounts for
1.35% of the national GDP.
54.
The economic structure is: agriculture 25%, industry 37% and service 38%. The average GDP growth
rate for the past 5 years is 11.8%. In particular, agriculture: depends heavily on nature like water sources,
floods and other natural disasters. In higher regions, the crop yield is lower, the cultivation area is unstable
and there is only one crop per year. Aquaculture: is developing faster in recent years and focusing on raising
tiger prawns in brackish water. Hydroelectricity: The area has a large hydropower potential, there has been
some new constructions like Song Tranh 2, Dak Mi River 4, Con River 2 and the upcoming constructions
such as the Song Bung 1, 4 and 5. Tourism: is developing fast with the tourism spots of Hoi An, My An and
My Son being its great advantages. The long and beautiful coastline is a major potential for tourism
exploitation. Industry: there are many industrial and economic zones such as Dien Nam - Dien Ngoc, Lien
Chieu, Chu Lai etc. which have been invested in recent years. Da Nang itself developed into an economic
center in the central region.
Social conditions
55.
Population: The population of the basin is 1787.6 thousand people, accounting for 2.12% of the
national population and 2.4% of all river basins’ total population. The average population density of the basin
is 113 people/km2. The population gathers crowdedly in Da Nang’s districts. Quang Ngai’s population density
is 251 people/km2. The average population growth rate of the basin: The average population growth rate of
the entire basin is 1.18%;
56.
Ethnicity: Ethnic minorities make up 38.2%. The ethnic minorities gather mainly in Kon Tum:
53.63%, followed by Quang Nam: 6.80% and Da Nang 0.57%.
57.
Employment in agriculture sector accounts for 44.52%, industry 19.37% and service 36.11%. The
proportion of employment in service sector is relatively high compared to other river basins. Unemployment
rate is 4.7%.
58.
Poverty rate of the whole basin is: 38.2%, of which, poor households mostly concentrate in Kon
Tum: 71.22%, then comes Quang Nam: 30.29% and Da Nang: 13.12%.
A3.7. Environmental Background in Tra Khuc -Ve-Tra Bong River Basin
A3.7.1. Natural features
59.
The Tra Khuc – Ve – Tra Bong river basin (Tra Khuc river basin) lies between latitudes 14 050’ and
15020’ North, longitudes 108010’ and 109000’ East. Tra Khuc river basin spans 11 districts and towns of
Quang Ngai and a part of Kon Plong district, Kon Tum province. The basin’s surface descends steadily from
the West to the East, starting from the high mountains in Kon PLong district, Kom Tum province at a height
of 1,300-1,500 m in the West, to the lowlands with an average height of 5-20 m. There is no significant
change in typography between the highlands and the lowlands. The highlands and the lowlands are next to
each other without nearly any transitory areas. This typographic feature creates straight flows from the
highlands to the lowlands, which can easily cause floods in the rainy season and drought in the dry season.
Tra Khuc – Ve – Tra Bong river basin area is 5,200 km2; Tra Khuc river is 135km long.
Climate
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60.
The average rainfall in the basin is about 2,890 mm. Rainfall tends to decrease from the North to the South
and from the East to the West. High rainfall focuses in high mountains such as Ba Tơ, Gia Vực (3,200-4,000
mm/year), while rainfall in the coastal lowlands only reaches 2,300-2,700 mm/year. There is a significant
difference in rainfall between the rainy season and the dry season. Rainfall is unevenly distributed throughout the
year. The rainy season lasts in 4 months, from September to December, making up 70-80% of the total annual
rainfall. High rainfall concentrates in October and November, accounting for 40-50% of the total annual
rainfall. The dry seasons begins in January and ends in August, whose rainfall makes up 20-30% of the total
annual rainfall. Months with the lowest rainfall are often February, April and August.
61.
The rainy season here lasts for 4 months, but the flood season lasts only for 3 months and often
begins 1 month later than the rainy season. The rainy season begins in September, but rainfall only accelerates
in October and then, the flood season begins. The flood season lasts from October to December, sometimes to
January of the next year. The month with the highest discharge is November. The dry season lasts for 8
months, when the discharge makes up only 30% of the total annual discharge. April is the month with the
lowest discharge. Flow in different months are uneven, the difference between the highest monthly discharge
and the lowest monthly discharge is very big.
Flow and floods
62.
Flow in the flood season: The flood season lasts for 3 months, from October to December, and is not
stable. The month with the highest discharge is November. The runoff in the flood season makes up 30% of
the total annual runoff. Apart from the main flood season, there are May rain-floods in May and June, and
early floods from August to early October and late floods from December to mid January of the next year.
63.
Flow in the dry season: In the dry season, the flow is small, the river flow is mainly supplied by
groundwater sources. The dry season starts from January to August, with a total runoff of only 30-35% of the
annual runoff. There are two dry period in the year, the first begins in April with an average discharge of 50.3
m3/s, and the second begins in July or August with the average discharge in August being about 61 m3/s.
Salinity intrusion
64.
In dry season months, the flow in the rivers is often small, which enables salinity intrusion to
increase. Based on the variation of the river flow, salinity intrusion is also divided into 3 periods: Early dry
season: January, February: Salt water intrudes river mouths and salinity tends to increase; Mid. dry season:
often from March – August, the salinity intrusion possibility is the highest. Influences from May rain-floods
forms two maximum points and one minimum point of the salinity intrusion, the strongest salinity intrusion
occurs in May, July, August, with the highest salinity in July. Late dry season: the salinity in the rivers
reduces quickly in the second half of September.
A3.7.2. Ecological features and cultural sites
65.
Tra Khuc river upstream’s ecosystem is characterized by the tropical closed forest ecosystem. There
is no Conservation area approved by The Government in the Basin. It indicates the conservation value and
environmental assets in the basin is very low.
66.
Basin forest cover rate is estimated 46% which is at medium level, compared to other basins. The rate
indicates the important role of forest cover to the sustainable development of the river basin. Basin native
forest rate is high 63.8% which indicates moderate forest quality and good catchment processes for runoff and
water quality. In general, native forest area of the Basin is less than other South Central coastal basins; mainly
of medium and poor forests.
67.
There is one Historical/Cultural Sites approved by The Government in the Basin. Heritage Index of
Vu Gia-Thu Bon basin is low-medium.
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Table A3.6: Ecological features of Tra Khuc, Ve, and Tra Bong river basin
Total area: 5,200 km2 of which 5,200 km2 are located in Vietnam
Environmental health: Biodiversity andecosystems
Characteristics
Included: terrestrial and aquatic and coastal ecosystems
 Tra Khuc river upstream’s ecosystem is characterized by the tropical closed forest
ecosystem
 Ecosystem of Vu Gia-Thu Bon river’s downstream is coastal ecosystem.
Conservation
areas


There is no Conservation area approved by The Government in the Basin.
It indicates the conservation value and environmental assets in the basin is very low

There is one Historical/Cultural Sites approved by The Government in the Basin that
is Cao Muon/Ba to.
Cao Muon Cultural and Historical Site is located in Ba Vinh, Ba Dinh, Ba Dien, Ba
Chua and Ba Cung communes, Ba To district. The site is centered on Mount Cao
Muon, an 829 m high mountain, situated north-west of Ba To town. Streams
originating in the east of the site flow into the Ve river, streams originating in the
north flow into the Ne river, streams originating in the west flow into the Lo river and
streams originating in the south flow into the Tra No river. The latter three rivers feed
the Ve river, which flows north through Quang Ngai province to meet the East Sea
south of Quang Ngai town.
Heritage Index of Vu Gia-Thu Bon basin is low-medium (1), compared to other
basins.
Historical/
Cultural Site


Major water
related
environmental
assets
There is no major water related environmental assets
Physical
condition
land use
proportions





Forest cover: 48%
Agricultural cover: 22%
Resident cover 2%
Specific use 3%
Other use 25%
Vegetation cover

Vegetation Index of Tra Khuc River Basin occupies 2.04% of total national forest
area, lower than other basins. This basin take a less important role to meeting the
national forest target
Basin forest cover rate is estimated 46% which is at medium level, compared to other
basins. The rate indicates the important role of forest cover to the sustainable
development of the river basin
Basin native forest rate is high 63.8% which indicates moderate forest quality and
good catchment processes for runoff and water quality. In general, native forest area
of the Basin is less than other South Central coastal basins; mainly of medium and
poor forests


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A3.7.3. Water quality
68.
The surface water quality in Tra Khuc – Ve – Tra Bong river basin is considered to be quite good
(BOD, COD, DO values are generally good). In the period 2005-2009, the BOD value only exceeded the
permissible limit once in 2006 in Tra Cau river in the My A sea mouth section (63mg/l), the COD exceeded
the limit twice in 2006 in the upstream of Tra Cau river (27mg/l) and in My A sea mouth (181mg/l).
69.
In general, surface water quality in the rivers varies differently. In Tra Cau river, according to
monitoring results, water in the sea mouth section has the lowest quality (BOD and COD values in this area
are 4 to 7 times higher than those monitored in the upstream and at Tra Cau river bridge). In Ve river,
monitoring results show that pollution levels in the upstream and sea mouth sections are quite similar (BOD
value exceeds the permissible limit by 1.2 to 2 times).
A3.7.4. Socio-economic conditions
Economic conditions
70.
The economic structure is: agriculture 34%, industry 27% and service 36%. The average GDP growth
rate for the last 5 years is 10.8%. Agriculture: basically fulfills the demand for food of the locality but the
growth rate is not high. Industry: focuses on several industrial establishments of small and medium scale.
Dung Quat Industrial Zone is under construction and of great development potential.
Social conditions
71.
Population: Population scale: 1,297.5 thousand people, accounting for 1.54% of the national
population. The average population density of the basin is 249 people/km 2. The population is unevenly
allocated, mainly gathering in cities and the delta. The average population growth rate of the basin is
1.48%.
72.
Ethnicity: Ethnic minorities make up 32.62%, mainly concentrating in remote communes of Quang
Ngai province and KonPlong district of Kon Tum province.
73.
Employment: Employment in the agriculture sector accounts for 60.77%, industry: 12.45% and
service 26.78%. It can be seen that the basin’s industry is underdeveloped while service is more developed.
74.
Poverty rate: The average poverty rate in the basin is 66.8%, the highest compared to the other 15
basins. Poor people gather mostly in mountainous districts: Son Tay and Tay Tra with nearly 100% is poor
households, then comes Tra Bong, KonPlong, and Son Ha with approximately 90% poor households.
A3.8. Kone River Basin (Binh Dinh)
75.
Kone river basin (including the Ha Thanh and La Tinh river basin) has an area of 3,640 km2, located
entirely within Vietnam territory and in the territory of Binh Dinh province. Kone River originates from the
Truong Son mountain, about 160 km of main stream flows Southeast through the mountains, then moves East
crossing the plains and pours into the sea. The basin’s terrain is relatively complex, lower from West to East.
It can be divided into mountain area, midland, coastal plain and coastal dune. Presently, forest cover is only
about over 40%, leading to the rivers causing floods each year and severe sedimentation. The map of Kone –
Ha Thanh river basin is presented in Figure A2.8 (Annex 2).
76.
The average annual rainfall is 1,700 – 1,800 mm. The rainy season, from August to December,
concentrates from 70 - 80% of the yearly rainfall. Since the rainy season coincides with stormy season, flood
often occurs. Prolonged dry season causes drought in many areas, the average humidity is 75%.
17
Environmental Assessment (EA)
Viet Nam Managing Natural Hazards Project (VN-Haz/WB5)
77.
May-rain flood usually occurs in May and June; early flood in the August and September; floods in
high season in October and November and late flood in December.
78.
Kone river basin’s ecosystem included: terrestrial and aquatic and wetland/mangrove ecosystems.
Lower montane evergreen forest is presented for forest ecosystem of Kone-Ha Thanh upstream; Ecosystem of
Vu Gia-Thu Bon river’s downstream is ecosystem like coral reefs, seagrass beds and coastal lagoons. There is
one Conservation are that approved by The Government in the Basin, that is Kon Cha Rang Nature Reserve
(15,900 ha). Conversation area index is estimated 4.37% is low-medium level, compared to other basins. The
index indicates the conservation value and environmental assets in the basin is low-medium level.
79.
There is only one Historical/Cultural Sites approved by The Government in the Basin, that is Quang
Trung Museum. Invaluable cutural heritages of Tay Son Period with architectural set of Tay Son Temple and
museum and martial arts house.
A3.9 Dinh river basin (Ninh Thuan)
80.
Dinh river basins (also called Cai river - Phan Rang) covers almost Ninh Thuan province. The river
originates from the Eastern slope of Gia Rich mountain bordering with Lam Dong province. The river flows
Northsouth and pours into the Eastern Sea through the Gulf of Phan Rang. The length of the main stream is
about 120 km. Total Cai river basin area is 3043 km2, in which, 2488 km2 of Ninh Thuan, 336 km2 of Khanh
Hoa, 172 km2 of Lam Dong and 47 km2 of Binh Thuan. The map of Dinh river basin is presented in Figure
A2.9 (Annex 2).
81.
Due to the terrain of the upstream surrounded by high mountains, the basin’s annual rainfall is very
large, from 1000 - 2000 mm. The basin has a tropical monsoon climate, with two obvious rainy and dry
seasons. Rainy season is from July to November, dry season from December to June of the following year.
Rainfall tends to gradually increase from the plains to the mountainous area. The average rainfall in many
years in the coastal area is about 600 mm, in Phan Rang it is 712 mm, and Tan My 1,071 mm. In the high
mountainous upstream part, rainfall may reach above 2000 mm.
18