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Saudamini Das, Assoc Prof. Institute of Economic Growth, Delhi, and SANDEE Fellow

Economics of Climate Change Adaptation Workshop, USAID, UNDP, ADAPT Asia-Pacific, 24-26 Oct 2012, Bangkok

Conserving Mangroves for Storm Protection Services

The views expressed are those of the presenter and should not be attributed to either UNDP or USAID. Furthermore, it is strongly recommended that both the PowerPoint slides and the videos of the presentation of content included herein are viewed in conjunction in order that statements appearing in the PowerPoint slides are not interpreted out of context.

Approach to Storm Hazard

•There are limitations & uncertainty

• Accurate prediction of intensity, landfall with sufficient time gap

• Limited compliance of community to State warning: (wait & watch, faith on GOD, less faith on Govt)

• All investments limited to protection of movable properties

• Uncertainty from Climate change

• Bay of Bengal, South China Sea and North Pacific Ocean are core area of Cyclogenesis (IPCC 1997)

• Emphasis on scientific & engineering approach to storm risk management by policy

• Better prediction• Early warning• Evacuation• Storm shelters, storm resistant houses, dikes

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Natural buffers are important - need to examine their role

• Do mangroves provide storm protection ?

- historical context, - concerns, knowledge gap - careful examination of this service

• Is mangrove preservation an economically viable adaptation strategy to climate change?

• How do they fare vis-à-vis the other approaches like early warning, storm shelter, dikes, etc?

Mangroves break, stop and channelise the storm surge

• Debated since the Bhola Cyclone (Nov 1970) in East Pakistan (Bio.Conserv, 1971)

• Much focus due to prominent natural disasters like 2004 tsunami, Katrina, Sidr, Nargis, Aila etc.

• Accepted as a prominent ecosystem service (Barbier et al, Science 2008; Day et al, Science 2007; Gedan et al, Climate Change 2010).

• Most of the empirical works are questioned.

Storm protection by Mangroves - Background

• Quantifies Mangrove Protection during 1999 Super Cyclone

• Examines mangrove protection for movable as well as immovable properties (house damages)

• Large sample and maximum possible control to separate Mangrove impact on Cyclone Damage

• Use Scientific, GIS and Socio-Economic data

• Robust finding that mangroves reduced cyclone damages and support for mangrove conservation to get storm protection

Present Study

Mangrove

District Boundary

River

LEGENDS

Kendrapada

Jagatsinghpur

Bhadrakh

Puri

Super Cyclone Path

Bay of Bengal

Mangrove Forest cover before 1950 (30,766 hectares)

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Casurina Dense

Casurina Open

Mangrove

Mix Jungle(Kaju)

District Boundary

River

LEGENDS

Kendrapada

Jagatsinghpur

Puri

Bhadrakh

Super Cyclone path Bay of Bengal

Mangrove Forest cover in 1999 (17,900 hectares)

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AB

Human death in Kendrapada

Description of Deaths

Area No of Villages

Mean death

Minimum

Maximum

Entire District 1180 0.39 0 21

Villages with no or little mangrove protection (M ≤ 0.5)

722 0.54 0 21

Villages with high mangrove protection (M > 0.5)

458 0.14 0 10

Villages inside mangrove habitat ( established by cutting mangroves)

96 1.11 0 13

Villages outside mangrove habitat

1084 0.32 0 21

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How do I identify Mangrove Impact during Cyclone?

• Estimate Cyclone Damage Function using multiple control variables along with mangroves

• Use variables to control for: - Physical features of mangrove habitat - Cyclone Impact - Topography - Hydrology - Infrastructure - Socio-Economic Well-being - Governmental Institution

• Calculate avoided damages from marginal effect

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Confounding effect of mangrove with effect of distance from coast

●

●Village A

Village B

Mangrove

Sea

---- with effect of Mangrove Habitat

A● C●

• Exclude village A, include village C

• Test that protection at B is due to vegetation, not habitat

B●

Sea

Mangrove habitat

Mangrove

Marginal effect - death (villages within 10km from

coast)

Variables Marginal Effect Variables Marginal Effect

Mahakalpada Tahasil

0.22 *** Droad 0.0006

Patamundai Tahasil

-0.06 Roadumy 0.04

Surge 0.02 Pop99 0.00005 ***

Dcoast 0.02** Literate -0.16

Mangrove -0.111*** Schedulcaste -0.10

Mhabitat -0.022 *** Cultivator 0.05

Topodumy 0.294 *** Aglabor 0.03

Casuarinadumy -0.045 Hhworker 0.958

Dmajriver 0.025 *** Margworker 0.36***

Dminriver -0.004 Otworker -0.26

Deaths averted by Mangroves

yyDA ˆˆ

,

Actual death due to super cyclone 392

Predicted deaths if there were no mangroves 603

Predicted deaths if current mangroves were at 1950 level

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Averted deaths under assumption 1

(603 – 392) = 211

211 (54%)

Averted deaths under assumption 2

(392 – 31) = 361

361 (92%)

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Other damages averted by Mangroves (%)

Damage type

1999 mangrove

1950 mangrove

Human death

54 92

FC 17 100

PC -17 -100

Cattle 15 67

Buffalo 27 52

yyDA ˆˆ

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Area / Mangrove unit

Value of 1km width

Value of 1 hectare

Village Rs3,928/ Rs217/

Entire study area

Rs33,39,166/ (USD 68, 586)

Rs1,82,080/ (USD 4335)

Storm Protection Value of Mangroves during super cyclone

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Type of damage Value/km of 1999 mangrove/village

Value/km of 1950 Mangrove/village

Human death 2743.95 1478.28

Fully collapsed houses 1368.55 3235.85

Partially collapsed houses

-245.59 -580.85

Fully collapsed + Partially collapsed

1123.36 2655

Buffaloes 8.77 4.83

Cattle 49.94 45.07

Weighted Average Storm Protection Value of km width of Mangroves per Village (in INR)

Will we optimize benefit by going back to 1950 level? NO

-.1

-.05

0.0

5.1

.15

avdeath

km

hm

ang

0 1 2 3 4 5hmangrvillage

X axis: km width of mangrove \ village

Y axis: averted death \ km width of mangrove \ village

Turning point: at approximately 1.5 km \ village

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Mangroves vs. others

Damage

Actual

Death without mangroves

Death without storm shelters

Death without early warning

Death without dikes

Human death

197 331 404 1602 257

• 74% of all the Swept Away houses and 80% of all the cattle loss in Kendrapada occurred from villages next to dikes.

Source: Das & Vincent ongoing (not to be quoted)

Source: Das (sandee@10)

Meteorology: • Orissa is the most cyclone prone state in east coast of India.• Frequency of high intensity cyclones increasing over years.

Period Frequency of VSCS & SC

Annual Probability

1900-1920 0 0.00

1920-1940 2 0.10

1940-1960 1 0.05

1960-1980 3 0.15

1980-2000 3 0.15

Should we preserve mangroves to adapt to climate change?

Yes, on both meteorological and economic grounds.

Economic cost & benefit (1999 prices)

Opportunity cost of conserving mangroves

• Market value of land in coastal Kendrapada: Rs172, 970 \ ha

• Annual return from land (8%): Rs13, 837\ha\yr

• Annual return from land(12%): Rs20, 756\ha\yr

Benefit from conserving mangroves

• Storm protection value (only for 3 damages):Rs182, 080\ha

• Annual Probability of VSCS and SC: 0.15\yr

• Annual Storm Protection Value (for 3 damages): Rs27, 312\ha\yr

Does reduction in only death risk justify mangrove preservation?

Benefit from death risk reduction

• No of lives saved: 0.01 \ ha• VSL for Orissa from Indian wage-risk study: Rs10,918,132\ • Annual probability of VSCS &SC: 0.15\yr• Annual benefit from reduction of death risk : Rs17, 469\ha\yr

• Opportunity cost of Mangrove Preservation: Rs13, 837 – Rs20, 756\ha\yr

Benefit ≥ Cost

• VSL for India: Rs13.7-14.2 to Rs55.5-60.6million at 2000 - 01prices ≈ Rs17.8-18.4 to Rs72 -78.12m at 2002-08 Per capita income.

Conclusions

•Mangroves reduced human death, livestock loss and house damages during the T-7 Super cyclone of October 1999.

• Human death toll would have been nearly doubled in absence of mangroves.

•Annualized storm protection benefit of mangrove for reducing three damages was found higher than annual return from land justifying mangrove conservation as a viable adaptation strategy to climate change.

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Policy Implications

• Use of engineering approach to manage storm disaster may not be the only option.

•Along with engineering and scientific approaches, mangrove protection and regeneration should be undertaken to manage storm risk more efficiently

• Along with movable properties like lives, mangroves also protect immovable assets like houses.

THANKS