Coastal Adaptation Mixing Gray and Green Infrastructures to Climate Change in Vietnam

1

January 23, 2019@Hanoi, Vietnam4th NIES International Forum

Makoto Tamura*Institute for Global Change Adaptation Science,

Ibaraki University, Japan

This study was partly supported by the Environment Research and Technology Development Fund (S‐14&2‐1712) of the Ministry of the Environment in Japan.

Soc Trang, Vietnam, 2015

2015/11/24

2015/11/24

3Tamura et al.(2018)

Method

Impact assessment with and without adaptationDike and

mangrove

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Impact assessment with and without adaptation<No adaptation>・Inundated area and coastline・Affected population・Economic damage

Steric sea level rise ・MIROC-ESM・RCP (8.5)

Construction of elevation data in land and sea・ETOPO1=> smoothing for land elevation and water depth･TPXO7.2=> mean higher high water level (MHHWL)

Calculation of inundation ・Compare land elevation with sea level ・Water intrusion from the coastline

Socioeconomic scenarios・Downscaled SSP 1-3

(0.5×0.5 degrees)

<Adaptation: dike & mangrove >・Inundated area and coastline・Affected population・Economic damage・Cost of adaptation・Benefit-cost of adaptation

Cost database of adaptation・Dike & mangrove

Kumano et al.(2018)

Potentially inundated area (SLR&tide)

6Potentially inundated areas and affected population due to SLR and high tide(MIROC‐ESM)

SLR by MIROC-ESMPotentially inundated areas is

calculated without protectionSSP1-3

scenarios(0.5°*0.5°) Murakami and Yamagata(2016)

Potential inundated areas due to SLR and high tide at 2100 (MIROC‐ESM, RCP8.5 )

Modified from Yotsukuri et al.(2017)

inundated area

Coastal inundation due to SLR in some countries (MIROC-ESM)

Inundated rate= potential inundated area/Land area

MIROC-ESM, RCP/SSPTop 10 inundated countries are

almost the same regardless of GCMs (Tsuchida et al. 2018)

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Potentially inundated areas

Modified from Yotsukuri et al.(2017) Affected population

Cost of coastal adaptation

Design standards and cost database of adaptations from world projects

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14 countries 89 points20 countries 455 points 20 countries 134 points

10 102 103 104 1050

10

20

30

40

Real GDP/Capita(US$)

Cos

t (10

KU

S$/h

a)

アメリカ(21)インド(2)インドネシア(1)エリトリア(1)オーストラリア(12)タイ(7)ニュージーランド(1)

バングラディッシュ(1)フィリピン(10)ブラジル(7)ベトナム(9)マレーシア(14)メキシコ(2)モザンピーク(1)

アメリカ(70)イギリス(5)イタリア(3)インドネシア(7)オーストラリア(5)オランダ(9)ガーナ(1)カンボジア(1)シリア(4)スペイン(2)

デンマーク(2)ドイツ(3)バングラディッシュ(1)フランス(2)ベトナム(5)ベルギー(1)ポルトガル(1)ホンデュラスラトビア(2)南アフリカ(1)

10 102 103 104 1050

10

20

30

40

50

Real GDP/Capita(US$)

Cos

t (U

S$/m

3 )

10 102 103 104 105

010

20

30

40

50

6070

Real GDP/Capita(US$)

Cos

t (M

US$

/km

)

全球費用

USA(94)UK(22)Italy(1)Indonesia(10)Estonia(1)Australia(4)Netherlands(28)

Ghana(2)Cambodia(6)Syria(6)Thailand(1)Denmark(1)Germany(16)Bangladesh(2)

Brazil(3)Vietnam(58)Honduras(4)Latvia(1)South Africa(2)Japan(194)

USA (94)UK (22)Italy (1)Indonesia (10)Estonia (1)Australia (4)Netherlands (28)

Ghana (2)Cambodia (6)Syria (6)Thailand (1)Denmark (1)Germany (16)Bangladesh (2)

Brazil (3)Vietnam (58)Honduras (4)Latvia (1)South Africa (2)Japan (194)

MangrovesBeach nourishmentDike/sea walls

Unit cost of coastal adaptations (Kumano et al. 2018)

USA(21)India(21)Indonesia(1)Eritrea(1)Australia(12)Thailand(7)New Zealand(1)

Bangladesh(1)Philippines(10)Brazil(7)Vietnam(9)Malaysia(14)Mexico(2)Mozambique(1)

USA(70)UK(5)Italy(3)Indonesia(7)Australia(5)Netherland(9)Ghana(1)Cambodia(1)Syria (4)Spain (2)

Denmark(2)Germany(3)Bangladesh(1)France(2)Vietnam(5)Belgium(9)Portugal(1)Honduras(1)Latvia(4)South Africa(2)

Assessment of adaptations

Case 1: Dikes will be constructed along the entire inundated coastline in response to SLR.

Case 2: Mangroves will be planted periodically in inundated coastal areas where mangrove forests already exist. Dikes will be only constructed along inundated coastline where there is no mangrove forests.

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Dike Durability is 30 years

MangroveForest grows for 30 yearsForest life is 50 years2% decrease in area per year

Maintenance CostCj,t(US$):Durability(30 years)d(year):

Length of the inundated coastline (km) Lj,t(km):

Construction Costs

Case 1: Dike protection only Case 2: Combination of dikes and mangroves

Around 250m of mangroves alongthe coast are assumed to have aprotection effect equivalent to thesame length of dike.

Assumptions

1km

250m

, , ,t j t j t j tAC L UC MC

, , ,1

j t j t j tMC L UCd

Mangrove protectionGrowth scenarios of planting mangrove

• Plant every 5 years to compensate the decreased amount• Initial and maintenance costs

1t at

BAYe

tts e s

t t tY s Y BA：area of mangrovea：growth parameter(0.4) ： lifetime parameter(0.1)

• Growth rate: sigmoid type • Survival rate：

0.00

0.20

0.40

0.60

0.80

1.00

0 20 40 60 80 1000.00

0.20

0.40

0.60

0.80

1.00

0 20 40 60 80 100

Amount of planting  

Cost of plantingmangrove t mangroveAC M c

0.1st t t t n t nM Y Y Y Y

Impacts of SLR

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LandMangroveMangrove outside of landOcean Inundated area

Potentially inundated area under RCP8.5 

Affected population under RCP8.5 

2020 2040 2060 2080 2100

36

38

40

42

Inun

date

d ar

ea(1

03km

2 )

34

32

30

2020 2040 2060 2080 2100

10

12

8

14

16

18

20

Affe

cted

pop

ulat

ion

(106 )

SSP1

SSP2SSP3

Kumano et al.(2018)

Potentially inundated area in 2100 and mangrove distribution(MIROC‐ESM, RCP8.5, TroCEP)

Economic damage and adaptationcost in Vietnam (MIROC-ESM)

Economic damage > cost of adaptationCost of only dike > cost of

mixing dike & mangrove

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Economic damage due to SLR and tides (RCP8.5)2020 2040 2060 2080 2100

35

25

10

0

30

15

5

20

Econ

omic

dam

age(

109

US$

) SSP1SSP2SSP3

B/C of adaptation (RCP8.5)

SSP1 Dike + MangroveSSP1 DikeSSP2 Dike + MangroveSSP2 DikeSSP3 Dike + MangroveSSP3 Dike

2020 2040 2060 2080 2100

30

20

10

0

Ada

ptat

ion

cost

(109

US$

)

25

15

5

Cost of adaptation (RCP8.5)

SSP1 Dike + Mangrove

SSP1 DikeSSP3 Dike + Mangrove

SSP3 Dike

SSP2 Dike + Mangrove

SSP2 Dike

Kumano et al.(2018)

Economic damage and adaptationcost in the world (MIROC-ESM)Adaptation => raising dikes (new dikes or upgraded dikes)

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Cost of adaptation Economic damage w & w/o adaptation     (three‐function estimate) Tamura et al.(2019)

Inundated area w & w/o adaptation Affected population w & w/o adaptation

Multiple Protection

Mixed techniques which are suitable for local situationMultiple protection, harmonized with ecosystem and livelihoodsArtificial beach

nourishmentMangroveGabion

(a) Combination with artificial beach nourishment

(b) Combination with mangrove plantation

(c) Combination with gabion

Mangrove

ReinforcedLevee

Wave eater(e.g., Distorted Ripple Mat)

Artificial Beach Nourishment Reinforced

LeveeBreaking wave

GabionReinforced

Levee

Wave eater(e.g., Distorted Ripple Mat)

Breaking wave

Wave eater(e.g., Distorted Ripple Mat)

Breaking wave

Yasuhara et al.(2016)

Optimal climate change adaptation strategies using green & gray infrastructures

From scientific assessments to policies

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Research image

Concluding remarks

Global impact assessment of SLR based on RCP/SSPCoastal vulnerability in the Mekong Delta and Red River Delta Impact and cost analyses of coastal protection using both gray and green infrastructures against SLROnly dikes vs. mixing dikes and mangroves

• Economic damage > cost of adaptationMultiple protection, harmonized with ecosystem and

livelihoodsResilient adaptation strategies that are suitable in local situationScientific assessment and collaboration with local

stakeholders

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References Kumano N, Tamura M, Inoue T, Yokoki H (2018). Estimating the cost of coastal protection using

green infrastructure against sea level rise in Philippines and Vietnam. Journal of Japan Society of Civil Engineers G (Environment), 74(5), I_395-I_404 (in Japanese).

Ling FH, Tamura M, Yasuhara K, Ajima K, Trinh VC (2015). Reducing flood risks in rural households: Survey of perception and adaptation in the Mekong Delta. Climatic Change, 132(2), 209-222.

MONRE (2016). Climate change and sea level rise scenarios for Viet Nam. Ministry of Natural Resources and Environment.

Murakami D, Yamagata Y (2016). Estimation of gridded population and GDP scenarios with spatially explicit statistical downscaling, ArXiv, 1610.09041.

Tamura M, Yasuhara K, Ajima K, Trinh VC, Pham SV (2018). Vulnerability to climate change and residents’ adaptations in coastal areas of Soc Trang Province, Vietnam. International Journal of Global Warming,16(1), 102-117.

Tamura M, Yotsukuri M, Kumano K, Yokoki H (2019).Global assessment of the effectiveness of adaptation in coastal areas based on RCP/SSP scenarios. Climatic Change, 15p. (in press).

Tsuchida K, Tamura M, Kumano N, Masunaga E, Yokoki H (2018). Global impact and uncertainty assessment of sea level rise based on multiple climate models. Journal of Japan Society of Civil Engineers G (Environment), 74(5), I_167-I_174 (in Japanese).

Tuan LA, Hoanh CT, Miller F, Sinh BT (2007). Flood and salinity management in the Mekong Delta, Vietnam. In: Be TT, Sinh BT, Miller F (eds.), Challenges to Sustainable Development in the Mekong Delta: Regional and National Policy Issues and Research Needs. The Sustainable Mekong Research Network, 15-68.

Yasuhara K, Tamura M, Trinh CV, Do MD (2016). Geotechnical adaptation to the Vietnamese coastal and riverine erosion in the context of climate change. Geotechnical Engineering Journal of the SEAGS & AGSSEA, 47(1), 7-14.

Yotsukuri M, Tamura M, Kumano N, Masunaga E, Yokoki H (2017). Global impact assessment of sea level rise based on RCP/SSP scenarios. Journal of Japan Society of Civil Engineers G (Environment), 73(5), I_369-I_376 (in Japanese).

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