A
ee VIEN KHOA HOC VA CONG NGHE VIET NAM
Trang 2Tap chi
Khoa hoc va Cong nghé bién
Journal of Marine Science and Technology Số phụ trương (2007) Mục lục Contents Trang 1 Nguyen Huu Cu, Mauro Frignani, Gabriele Capodaglio Studying the 6
coastal lagoon environment in Central Vietnam
- Nghiên cứu môi trường đầm phá ven bờ ở miền Trung Việt Nam
2 Luu Van Dieu Status and changes in the water quality of the Tam Giang 20 - Cau Hai lagoon
Hiện trạng và diễn biến chất lượng nước hệ đầm phá Tam Giang - Cau Hai
3 Georg Giesser, Tran Anh Tu, Francesca De Pascalis, DO Trong Binh, 29
Nguyen Huu Cu, Mauro Frignani Hydrodynamic modeling of the Tam
Giang - Cau Hai lagoon, Vietnam
Mô hình thủy động lực đầm phá Tam giang - Cầu Hai, Việt Nam
4 Lang Van Ken, Nguyen Van Quan Status and changes in biotic 44
resources of the Tam Giang - Cau Hai lagoon
Hiện trạng và diễn biến tài nguyên sinh vật đầm phá Tam Giang — Cầu Hai
5 Tran Duc Thanh Tam Giang - Cau Hai: lagoon resource potential and 53
orientation for management
Hệ đầm phá Tam Giang - Cầu Hai: Tiềm năng tài nguyên và định hướng
quản lý
6 Stefania Romano, Luca G Bellucci, Silvia Giuliani, Mauro Frignani, 63 Nguyen Huu Cu, Dang Hoai Nhon General sedimentological
characteristics of the Tam Giang - Cau Hai lagoon (Central Vietnam)
Đặc điểm trầm tích hệ đầm phá Tam Giang - Cầu Hai (việt Nam)
Trang 32
Tap chi Khoa hoc va Céng nghệ biên, Phụ trương (2007) Tr 53 - 62 TAM GIANG - CAU HAI LAGOON: RESOURCE POTENTIAL
AND ORIENTATION FOR MANAGEMENT
TRAN DUC THANH
Summary: With an area of 21,600ha, a length of 70km and two inlets, The Tam Giang - Cau Hai (TG-CH) lagoon is the most typical in Vietnam and the largest in South East Asia The lagoon is of value in living resources with a total of 839 species, including 7 species of seagrass, 7 spices of mangroves, 230 species of fishes and 73 species of birds.of which 34 species are boreal migrants.The annual fishery production from both catching and aquaculture reached once 4,000 - 5.000 tons The lagoon is also a nutrient Storage, a breeding and spawning ground, and seasonal migration path of marine fishes and hence it it is of significance for coastal marine fisheries It has environmental functions such as climatic and hydrological regulation, ground water maintenance, burying wastes and cleaning environment; values of tourism, agricultural production, waterway and harbors, settlement of beating fishermen, and values of culture, science and education
Thus, this lagoon has taken part in the development of regional SOcIO-econonly concerning 10 thousand of boating nomads, 19.5 thousand inhabitants on the shore and over 300 thousand residents of 40 lagoonal communes of 5 surrounding districts
Under the pressure ofsocio-economic development as well as population growth, the lagoon resources and environment are facing up to problems on the pollution of oil and domestic wastes; overexploitation and habitat damage Jeading to the degradation of living resources, and conflicts of use The coastal risky such as inundation desalination, salt IMIFUSTION, sedimentation, and inlet replacement and closing often occur due to cHmate change and human activities,
in reason for this, lagoonal resource management and protection, including establishing a natural conservation area in form of Ramsar Site or Biosphere Reserve are a realistic and urgent action
I INTRODUCTION
Trang 4north and Tu Hien in the south It is 21,600ha in area, | - 10 km wide, 1.5 - 2m deep on average and even over 10m deep at the Thuan An inlet
The TG-CH lagoon is the largest in Southeast Asia and typical for monsoon tropics With a great potential of natural resources, it plays a very important role for the coastal ecology and socio-economic development of the Hue region, where there was once Vietnam's Ancient Kingdom Capital newly recognized as a World Cultural Heritage Under the pressure of economic development and population growth, the lagoon is facing up to urgent problems of resources and environment degradation, and a suitable orientation for management is necessary 10/27 107%7 ‡ ‡ LEGEND 1 2 5
CAU BAL LAGOGN
1 Moutain 4 Old sand dunes
? Coastal plain 5 Sea and lagoon waters
3 Young sand dunes
102? tr
Trang 5I] POTENTIAL OF LAGOONAL RESOURCES
1 Biodiversity
Species diversity
A total of 839 species, including7 species of seagrass, 7 spices of mangrove, 230 species of fishes and 73 of species waterfowl have been recorded so far in the lagoon
(Thanh, T.D et al., 1997)
The flora in the Tam Giang-Cau Hai lagoon is composed of 221 species of phytoplankton, 54 species of phytobenthos, 47 species of algae, 19 species of watergrass (hydrophytes), among which are 7 species of seagrass and 12 species of freshwatergrass, and 31 species of plant,inluding 7 species of mangrove The ecological distribution of the flora has formed communities, of which the watergrass community is the most typical and important for lagoon
The fauna in the Tam Giang-Cau Hai lagoon consists of 467 species from
zooplankton (66 species), zoobenthos (98), fishes (230) and birds (73), among which are
80 species with a high economic value, including 23 species of fish, 12- shrimp, 18- crab
and some species of molluscs (Phu, V.V., 1995; Thị, N.N , 1996) The species of
fish-Cyprinus centralis Nguyen et Mai is not only an endemic but economically important one as well and considered to be special food Two species of shrimp-Penaeus monodon and Metapenaeus ensis have a high economic value and are often exported Among the 73 species of birds are 28 species with a high economic value, 30-inscribed in EU's list of strictly-protected birds (Ramsar Conservation Bureau, 1997) and 1- in Vietnam's Red Book
(Limnodromus semipalmatus)
Diversity of habitat and subecosystems
Many habitats/subecosystems can be found in the lagoon They are small estuaries, grass marshes, mangrove swamps, lagoonal tidal flats, freshwater grass and seagrass beds, and soft bottom The freshwater grass and seagrass beds are composed of 19 species of hydrophytes, but the most ecological significant species are Valisneria spiralis, Ceratophyllum demersum, Najas indica (fresh watergrass), Halophyla ovalis, H beccarii, Halodule pinifonia, H uninervis, Cymodocea rotundata, and Ruppia maritima (seagrass) The mangrove swamp is characterized by Kandelia canden, Bruguiera gymnozhina, Annona glabra, Excoecaria agallocha, Clerodendrum inerme and Ipomoea pescaprae The small estuaries, grass marshes are also waterfowl grounds in winter for over 20 thousand
individuals of birds (Thanh, T.D et al., 1 997)
Trang 6Diversity of faunal and floral origins
This is caused by the transfer location between the coastal zone of theTonkin Gulf
and Central Vietnam, and between the land and sea For example, the fish fauna is
originally similar to that in the north estuaries, meanwhile planktons and zoobenthos are similar to those in the south lagoons The fresh water phytoplankton are dominant with 52% of the number of species in rainy season and in turn, marine phytoplankton are dominant with 80% in dry season (Phap, T.T., 1993) Among the 73 species of birds are 34 species.of boreal migrants
2 Values of environment resources and ecological functions
Coastal nursery ground and nutrient store
The lagoon is also a nutrient store, nursery and spawning grounds, and seasonal migration path of marine fishes, hence it is of significance for coastal marine fishery
(Thanh, T D et al, 1996a, 1996b; Tien, N.V et al, 2001) The most important note on the
food chains in the TG-CH lagoon is the presence of hydrophytes aside from phytoplankton and other consumers as food for fishes (Siganus guttatus, Cyprinus centralis, Siganus oramin, Ctenopharyngodon idellus, etc.) Not only do hydrophytes serve as food for fishes but locally exploited objects for human multiuse as well
Harmonization for coastal environment
Being a coastal and natural functioning system located in a transborder position between the mainland and ocean and as a large natural reservoir, the lagoon controls the coastal flood and creates a balance of water levels It traps sediments and buries all kind of domestic wastes and self-purifies to stabilize the environment quality It stabilizes the groundwater level for farming soil surrounding the lagoon, which is inherently composed of sand or mainly of sand, and mitigates storm surges and landward salt-intrusion The lagoon harmonizes and mitigates the severity of regional climatic factors (Thanh, T.D et al., 1997.)
3 Potential for the socio-economic development
Inhabited areas
Exploiting and culturing lagoonal aquatic products have attracted about 13 thousand of labors and supported directly the life of 33.5 thousand persons The lagoon environment and
resources concern the survival of 10 thousand of boating nomads, 19.5 thousand inhabitants
Trang 7great role for the socio-economic development in the region, and had great effects to the development of Hue Capital before as well as Hue City nowadays (Thanh, TD et al., 1997)
Fishery production
Fishing productivity is about 2,500-3,000 tons/year but 4,500-5,000 tons/year in the period 1970-1975 Aquaculture are fairly developed in an area of about 1530 ha for shrimp, crab, fish, sea weed (Gracilaria tenuistipitata) in form of pond, cage and raft Seaweed yield is 400 dry tons/year Shrimp production is 200-700 kg/ha/year Besides this,
seaweeds, water grasses and molluscs are harvested (Hien, N.L., 1997; Thi, N.N., 1996) Agriculture
A part of lagoonal marshes is used for unusual rice cultivation (one crop or two crops) with a low productivity of 1-5 tons/ha/year There are also hundreds of thousand individuals of ducks and thousands of cattle cultured in the lagoon About 150,000 tons of seaweeds and seagrasses are yearly exploited for fertilizer for culturing rice , peanut, sesame, pepper and tobacco crops and for livestock (Thanh, T.D et al., 1997; Nam, D et al, 1998))
Figure 2:A ground of blackcoots
Figure 3: Aquaculture ponds (Fulica atra) in the TG - CH lagoon in the TG - CH lagoon
Waterway, harbor and Jishery infrastructure
The lagoon has been used for waterway, marine fishing harbors and as a refuge for ships and boats during thestorms.The Tan My harbor is now for 1,000 DWT ships but it is designed for 3,000 DWT ships until the year 2010 The lagoon supports a dense residential community with fish processing plants, trade and service Three districts, Quang Dien, Phu Vang and Phu Loc, had 3267 marine fishing boats and vessels, and 3928 lagoonal fishing boats with a total of 12 300 fishing labors, (Hien, N.L., 1997)
Trang 8Tourism and outdoor recreation
The beautiful landscape here is impressive with calm and clear water surface, vast sand dunes, and grass swamps crowded with waterfowls From the lagoon, one can travel upstream to the Hue City Centre via the Huong River Beautiful beaches like Thuan An and Vinh Hien with holiday cottages, and recreational activities of boating, fishing, and surf-riding can turn tourism into a potentially lucrative economic sector Around the lagoon, there are a number of historical and cultural sites, festivals and unique customs that needs to be preserved as they have potentials to share in economic benefits through tourist
operations ( Nam, D et all, 1998) Culture, education and science
The lagoon boasts aesthetic values that inspire poetry and painting The local custom, traditional festivals and rituals reflect these cultural values The lagoonal area possesses plenty of historical relicts and has shared in the historic vicissitude for hundreds of years The O Lau River for many years functioned as the Cham-Viet border Thuan An inlet was used to be the anchorage for French gunboats attacking Hue Citadel The lagoon in one time was crowded with boats running to and from the Thanh Ha Ancient Harbor in Bao Vinh There are likely to be many archeological remains of the Bau Tro and Sa Huynh cultures, and later feudal regimes in the region (Nam, D et al, 1998)
The lagoon ecosystem has proven to be an educational site for students and pupils in their excursion or practical courses on ecology, environment and natural resources Numerous undergraduate, graduate and post-graduate theses on this lagoon have been conducted The lagoon ecosystem has a high scientific value for research of ecology, living resources, experiential biology, coastal geomorphology and dynamics
I ORIENTATION FOR MANAGEMENT 1 Needsfor management
Pressure from population
The lagoonal environment and resources have been impacted directly by activities of 10 thousand lagoonal boating nomads, 30 thousand inhabitants in the lagoonal rim of 40 lagoonal communes belonging to 5 districts (Binh, N Q V 1996) Annually, the rate of population increase is very high, from 2 to3%
Pressure from the economic development
Trang 9been accelerated from the pressure of growing population, habitat destroying abuse such as electricity, blasting and nets with too small meshes Overharvesting watergrasses for fertilizer, livestock food has caused the deterioration of living resources and of biodiversity (Thanh, T.D et al., 1997.)
Agricultural land reclamation activity has destroyed the grass marshes where waterfowls are frequently resident Bird hunting initially occurs Agricultural land reclamation, irrigation, dike and dam construction, pond building, and cage and raft culturing have narrowed lagoonal waters, decreased water exchange but increased coastal inundation-flood
Activities of port, fishing harbors and waterway transportation have caused oil pollution with a high concentration over 0.05 mg/l.Agricultural and industrial activities have created contaminants of heavy metals and pesticides both in lagoonal water and sediments Due to the domestic wastes,lagoonal water has been locally polluted by the organic matter
and coliform density has exceeded 1,000 MPN/100ml (Hoi, N.C et al,, 1995) The
construction of reservoirs in the watershed can reduce locally nutrients to the lagoon Coastal risks
Coastal risks often occur to the lagoon area such as inundation,flood, water
desalination and lagoon inlet unstability During the terrible coastal flood on1-6 November1999,3 of 5 inlets were newly opened, over 300 people died and a total loss was estimated at nearly 2 000 billion VND The upper stream deforestation for cultivation and wood has made water turbid, water balance changed, coastal lowland inundated, lagoonal water fresh in rainy season, and seawater penetrated in dry season Especially, the Tu Hien inlet closure every duration of 4-11 years makes lagoonal waters fresh and causes a number of great changes to ecosystem (Thanh, T D., 1997) Around the lagoon, the sand flowing and sand blowing from sand dunes have taken part in shallowing the lagoon The natural tendency of lagoon evolution is to be shallow and narrow because of sedimentation
Conflicts of the lagoonal resource use
The conflicts are manifested in the dispute of resource use and mutual negative environmental impacts among the sectors such as agriculture, fishery and transportation, etc and among the sub-sectors, for instance, aquaculture and catching, preventing salt
intrusion and controlling flood inundation, etc (Hoi, N.C et al., 1995)
2 Orientation for management
A resolution of TG-CH lagoonal resource management is establishing a natural conservation area in form of Ramsar Site or Biosphere Reserve Area as a realistic and urgent demand A natural conservation area should be proposed with four basic functions:
Trang 10Conservation of biodiversity and aquatic living resources; Habitat and natural landscape protection;
Protection and growth of waterfowl population; and
Pollution prevention, natural hazard mitigation in the coastal area
In process of the submission to Vietnam’s Government and IUCN or UNESCO to recognize Tam Giang - Cau Hai lagoon as a national natural conservation area of Ramsar site or Biosphere Reserve Area, some technical resolutions need to be implemented urgently
- Stabilizing the inlets of Thuan An and Tu Hien - Controlling overexploitation of lagoonal resources - Protecting the spawning and breeding grounds
- Rehabilitation of habitats as seagrass beds and marshes - Developing aquaculture by a suitable planning
- Monitoring of water quality, biodiversity and habitat changes
- Management of lagoon risks such as inlet enclose, inundation, desalination, salt intrusion - Changing fishery structure with strengthening offshore catching
- Onshore settlement for boating nomads
IV CONCLUSION
The TG-CH lagoon is rich in natural resources for the coastal socio-economic development The lagoon also takes a very important function in coastal ecology and environment that influence deeply the survival of approximately one million inhabitants in the region Under the pressure of population growth and economic development, environment and natural resources of the lagoon, especially living ones, tend to be degraded and decreased seriously Due to the natural and human impacts, lagoon risks such as flood , inundation, salt intrusion, enclosing inlet, etc.are increasing both in frequence and critical level The conflicts are apparent in form of the dispute of natural resource use and mutual negative impacts
Trang 1110 11
REFERENCES
Nam, D, Mien, N., Thanh, T.D., Hoi, N.C., Cu, N.H., Tien, N.V., Thi, N.N.,
Lan,T.D.,1998 Impact of wetland preservation at Tam Giang-Cau Hai lagoon system Proc.Workshop on management and protection of coastal wetlands in Vietnam Hue City.p.68-80
Binh, N Q V 1996 Management of aquatic living resources in the Tam Giang coastal lagoon Thuan Hoa Publishing House, Hue
Hien, N.L., 1997 State and oriented development of fishery of the Tam Giang coastal lagoon in relation to the Thua Thien Hue region In: Marine resources and environment Sci & Tech Vol.4 Pub House Hanoi p 338-350
Hoi, N.C., Nam, D., Thanh, T.D and Mien, N., 1995 Study on the exploitation and
suitable utilization of natural resources potentials from the Tam Giang-Cau Hai coastal lagoon Project report coded KT-DL-95-09 reserved at Haiphong Institute of Oceanology
Phap, T.T., 1993 Research in the aquatic flora in Tam Giang -Cau Hai lagoon in Thua Thien Hue Ph Doctor thesis Hanoi
Phu, V.V., 1995 Fish fauna and biological characteristic of ten economic fish
species in the lagoon system in Thua Thien-Hue Ph Doctor thesis Hanoi
Ramsar Conservation Bureau, 1997 The Ramsar Convention Manual A guide to the convention on Wetlands 2™ edition
Thanh, T D., Hoi, N.C., and Thi, N.N.,1996a Principal issues on ecosystem of
Tam Giang - Cau Hai lagoon In: Marine resources and environment Sci & Tech Pub Vol.3 House Hanoi p.206 - 219
Thanh, T.D., Lan, T.D and Cu, N.H., 1996b Potentials to use and the management
of coastal lagoons in Central Vietnam Scientific activity No 9
Thanh, T.D., Cu, N.H and Lan, T.D., 1997 Estimation of wetland potentials and
the proposal to establish a wetland protected area of the Tam Giang coastal lagoon Project report managed by Thua Thien-Hue DOSTE
Thanh, T D., 1997 Environment impacts of enclosure and displacement of inlets of
Tam Giang - Cau Hai lagoon Marine Environment and Resources, Vol 4, Science
and Technology Publishing House, Hanoi, p 185-196
Trang 1212 13
Thi, N.N., 1996 Biological potential and aquatic living resources in Tam Giang-Cau Hai lagoon {Thua Thien-Hue province) Marine Environment and Resources, Vol.3, Science and Technology Publishing House, Hanoi, p 220-233
Tien, N.V., Hien, N.L., Trong, P.V., Thanh, T.D., 2001 Investigation of spawn and
nursery grounds in the coastal lagoon in Thua Thien-Hue and proposal of protected solutions for them Technical report of project, reserved at MOSTE of Thua Thien-Hue province
HE PAM PHA TAM GIANG CAU HAI:
TIỀM NĂNG TÀI NGUYÊN VÀ ĐỊNH HƯỚNG QUẢN LÝ
TRẦN ĐỨC THANH
Tóm tắt: Hệ đâm phá Tam Giang Cầu Hai (TG - CH) ở tỉnh Thừa Thiên Huế có diện tích khoảng 21.600ha, chiêu đài 70km và hai cửa lạch, điển hình nhất Việt Nam và lớn nhất Đông Nam Á hệ có giá trị lớn về tài nguyên sinh vật Khu hệ sinh vật được biết có 839 loài, đặc biệt là có 7 loài cỏ biển, 7 loài thực vật ngập mặn, 230 loài cá và 73 loài chỉm, trong đó có 34 loài chỉm di trú Sản lượng thuỷ sản đâm phá, bao gồm cả đánh bắt và nuôi trồng đã đạt tới 4000 - 5000 tấn Inăm Hệ còn là nguồn định dưỡng, bãi giống và bãi để, nơi đi cư theo mùa của cá biển, nên có ý nghĩa lớn đối với nghề cá ven bờ hệ đâm phá có giá trị lớn về chức năng môi trường như điều hoà khí hậu và thuỷ văn, duy trì nước ngầm, chôn vùi chất thải và làm sạch môi trường, có giá trị du lịch, sẳn xuất nông nghiệp, giao thông cảng, nơi cư trú tâu thuyền và các
giá trị về văn hoá, xã hội và khoa học
Thật vậy, hệ đâm phá có vai trò đặc biệt quan trọng đối với phát triển kinh tế xã hội
khu vực, liên quan đến 10 nghìn cũ dân thuỷ diện, 19,5 nghìn dân sống bao quanh và trên 300 nghìn dân thuộc 40 xã đâm phá của 5 huyện
Do áp lực phát triển kinh tế và dân số, tài nguyên và môi trường đâm phá đang phải đối mặt với những vấn đề ô nhiễm, khai thác quá mức và huỷ hoại gây suy thối tài ngun, mơi
trường và mâu thuẫn sử dụng đầm phá ngày càng gấy gắt Các tại biển ven bờ như ngập lụt, ngọt hoá và xâm nhập mặn, sa bồi, chuyển lấp cửa đâm phá thường xảy ra do tác động của biến đổi khí hậu và hoạt động nhân sinh
Vì vậy, các giải pháp quản lý và bảo tôn tài nguyên đâm phá trong đó có xây dựng các khu bảo tôn tự nhiên như Khu dự trữ sinh quyển hay Khu đất ngập nước có tẩm quan trong Quốc tế là một yêu cầu thực tiễn và cấp bách