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2017/EPWG/SDMOF/017 Thematic Session 2.5

Bamboo Fence Technology for Wave Height and Current Reduction, Accretion and Mangrove

Restoration to Protect Sea Dikes and Coastline of Viet Nam

Submitted by: Viet Nam

11th Senior Disaster Management Officials ForumVinh City, Viet Nam

21–22 September 2017

BAMBOO FENCE TECHNOLOGY FOR WAVE HEIGHT AND CURRENT REDUCTION, ACCRETION

AND MANGROVE RESTORATIONTO PROTECT SEA DIKES AND COASTLINE OF VIETNAM

Assoc. Prof. , Ph.D Trinh Van HanhDirector of Institute of Ecology and Works Protection

11th Senior Disaster Management Officials’ ForumVinh city, Nghe An Province, Vietnam, September, 21 - 22 , 2017

The role of mangrove forest1

3 Challenges and difficulties in mangrove forest rehabilitation

4Some measures to reduce waves, reduce current, accretion andmangrove forest restoration in Vietnam

5 Proposing measures to restore mangrove in Vietnam

Reality and Cause of mangrove forest decline in

Vietnam

2

CONTENT

The dike has not mangrove forest’s protection

The dike has mangove forest’s protection

Green wall protects the coast in a sustainable way for the coastal plain

Chart of Correlation between transmission and width of mangrove belt

The height of wave after transmission through the mangrove forest belt with a

width of more than 900m is less than 10%

I. THE ROLE OF MANGROVE FOREST

Climate control, CO2 absorption

CO2

CO2O2

O2

O2

Maintain biodiversity and aquatic resources

I. THE ROLE OF MANGROVE FOREST

Creating livelihood for people

Beekeeping

Exploit crabs in mangrove forest

Expand the area of the mudflats, limiting erosion and cleanning water environment

I. THE ROLE OF MANGROVE FOREST

The development of mangrove forests throughout the period in Vietnam

II. REALITY AND CAUSE OF MANGROVE FOREST DECLINE

Area(ha)

Time

Areas(ha)

Time

conversion of land mangrove forest use purpose

The acreage of mangrove forest land was converted to aquaculture land

Mangroves are converted to shrimp farming land in Vinh

Chau, Soc Trang

II. REALITY AND CAUSE OF MANGROVE FOREST DECLINE

The average amount of sediment in Mekong river in 1985-2000(Source: Lu, Siew 2006)

Because of reducing the amount of sediment that leads to erosion, deforestation

Coastal erosion in Ca Mau province

Coastal erosion in Tien Giang province

II. REALITY AND CAUSE OF MANGROVE FOREST DECLINE

Exploit in mangrove forest Deforestation Exploit seafood in mudflats

Mangrove forest decline because of exploitation activities of human

-80

-60

-40

-20

0

20

40

60

80

100

120

1 2 3 4 5 6 7 8 9 10

THEO NĂM 19 9 8 - 2 0 0 7

Mtb

Mtc

Mtt

II. REALITY AND CAUSE OF MANGROVE FOREST DECLINE

Chart of sea level rise in Vung Tau(Source: Nguyen Phu Quynh, Nguyen An Nien - Institute

of Irrigation Science)

Development of sea level in Rach Gia from 1998 to 2007(Source: International meeting on cooperation in river and

sea environmental protection in the Mekong Delta)

Cause of sea level rise

The area of the mangrove belt is negatively affected

Area of mangrove belt in favorable conditions

III. DIFFICULTIES AND CHALLENGES IN MANGROVE FOREST REHABILITATION

Seawater pollution

Negative impact on the growth and development of

mangroves

Decrease of sediment from the

river to the sea Poor nutrient Altitude is decreased

Decrease drying time

Waves impact on mangrove belt stronger

Reduce naturally recovery

Increased erosion,loss of forest

Poor growth

Decrease drying time

Wave stronger

Current shoreline stronger

Natural disasters increase

Increased

erosion,loss of forest

Climate change and sea

level rise

Water flow from the river

to the sea decreased

Salinity increased

Poor growth

Pressure on social and economic

development

Aquaculture

Farming

Transportation, irrigation

Industry

Tourism

Decrease mangrove

area

IV. SOME MEASURES TO REDUCE WAVES, REDUCE CURRENT, ACCRETIONAND MANGROVE FOREST RESTORATION TO PROTECT SEA DIKES ANDCOASTLINE

GeotubeCentrifugal concrete Hollow cylinder dike

Bamboo fence by WIP

(U – fence)T – fence

by GIZ

IV. SOME MEASURES TO REDUCE WAVES, REDUCE CURRENT, ACCRETIONAND MANGROVE FOREST RESTORATION TO PROTECT SEA DIKES ANDCOASTLINE

Bamboo fence to reduce waves Typical lay-out of bamboo fence in Nha Mat, Bac Lieu province

Bamboo fence to reduce currents

Advantages: Friendly environment, low price, responding to climate changeand sustainable development

Disadvantages: Not feasible at deep erosion sites and high wave intensityconditons

Building bamboo fence

IV. SOME MEASURES TO REDUCE WAVES, REDUCE CURRENT, ACCRETIONAND MANGROVE FOREST RESTORATION TO PROTECT SEA DIKES ANDCOASTLINE

Wave front and behind the bamboo fence system

The height result of meaning wave front and behind the bamboo fence

The measurement results of flow front and behind the bamboo fence

Sonneratia caseolaris 1-month-old seedling Sonneratia caseolaris are eligible for planting

Planting mangrove seedling Mangrove after planting 6 months

IV. SOME MEASURES TO REDUCE WAVES, REDUCE CURRENT, ACCRETIONAND MANGROVE FOREST RESTORATION TO PROTECT SEA DIKES ANDCOASTLINE

V. PROPOSING MEASURES

The mangrove forest restoration planning and land for mangrove forest restoration is the

basis for the protection, management, and development of coastal mangrove forests.

Using measures for wave reduction, current reduction, accretion and stabilization of

mangrove rehabilitation sites in mangrove areas not eligible for natural regeneration.

Researching on mangrove species adapted to higher salinity, deeper tides, stronger root

systems

Protecting the mangrove belt rehabilitation, supplement the seedling sources for alluvial

areas that are favorable for mangroves to grow and develop.

Planting mangrove with high density, and improving the mudflats which high sandy rate

Developing a reasonable mechanism for mangrove protection, management and

exploitation.

THANK YOU FOR YOUR ATTENTION!

11th Senior Disaster Management Officials’ ForumVinh city, Nghe An Province, Vietnam, September, 21 - 22 , 2017