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‘Water Security for Sustainable Development in a Changing Climate’

Discussion about water issues under changing climate

TOPIC:

WATER RELATED ISSUES IN THE MEKONG DELTA

By: To Quang Toan, toan_siwrr@yahoo.com

VIỆN KHOA HỌC THỦY LỢI MIỀN NAM

Southern Institute of Water Resources Research658 Vo Van Kiet street, Dist 5, HCM city

Tel: 08 39238320 Fax: 0839235028

Webs: www.siwrr.org.vn 2

1. Mekong Delta and water related issues

2. Unusual climate and hydrological condition in Mekong delta

3. Vietnam national projection for climate change and sea level rise

4. Change of hydrological flow: impact to flood and dry season flow

5. Salinity intrusion status

6. Change on sediment, riverbank and coastal zone erosion impacts

7. Sea water level rise, land subsidence and typhoons

8. Impact of climate change to Mekong delta

9. Conclusion and delivery messages

CONTENTS

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MEKONG DELTA AND WATER RELATED ISSUES1

4

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â

â

â

â

Pakse

Kratie

Ch©u §èc

Jinghong

Chiang SaenLuang Prabang

T©n Ch©u

H� Néi

Bangkok

Vientiane

Phnom Penh

Trung Quèc

Myanma

Th¸i Lan

Campuchia

ViÖt Nam

L�o

QuÇn ®¶o Ho�ng Sa

QuÇn ®¶o Tr−êng Sa

BIÓN §¤NG

BIÓN T¢Y

PhÇn th −î ng l−u t õ biª n giíi Tru ng Q

uèc vÒ ®Õn Kra tie

Ph Çn t h

−î ng l− u t h ué c Tru ng Qu èc v � M

ya nma

PhÇn th−îng l−u thuéc Campuchia ë d−íi Kratie

Vïng ®å ng b»n g C

h ©u thæ s«ng Mª C

« ng

§ång B»ng S«ng Cöu Long, ViÖt Nam

BiÓn hå Tonle Sap

C¸c ®Æc tr−ng chÝnh

DiÖn tÝch l−u vùc: 795.000 km (21)

ChiÒu d�i dßng chÝnh: 4.800 km (12)

L−u l−îng b×nh qu©n h�ng n¨m: 15.000 m /s

16%

2%

18%

35%

18% 11%

2

3

70 0 70 140 210 280 350 Kilometers

L−u vùc s«ng Mª C«ng h¹ thuéc L�o, Th i Lan, Campuchia v� VNTh−îng l−u tõ Trung Quèc ®Õn KratieTh−îng l−u §BSCL thuéc Campuchia sau Kratie§ång B»ng S«ng Cöu Long v� Phô cËnBiÓn Hå Tonle Sap

Th−îng l−u vùc s«ng Mª C«ng thuéc Trung Quèc v� MyanmaVïng Ch©u thæ Mª C«ngC¸c nh¸nh chÝnh trªn l−u vùc

Ú VÞ trÝ c¸c tr¹m quan tr¾c trªn dßng chÝnh Mª C«ngâ Th�nh phè, thñ ®«

Ranh giíi c c qu«c gia trong khu vùcDßng chÝnh s«ng Mª C«ng

S

N

EW

B¶N §å L¦U VùC S¤NG M£ C¤NG

GHI CHó

�Total area: 3.9 million ha

� Population:

18 million people

�Cultivated area:

> 2 million ha of rice,

up to 7crops per 2years

The Mekong Delta

Key figures of in the Mekong Delta

5

� Area: 12% of Vietnam

� Population: 21.5% of Vietnam

Contribute

� 50% of food production, 90% of

exported rice come from Mekong

delta

� 70% of fruit production

� >60% of the aquaculture production

(catch 44%, culture 75%) and 80%

national expoted value

Month

Problems1 2 3 4 5 6 7 8 9 10 11 12

Flood

Salinity Intrusion

Acid sulphate soil

and acid water

Drought

River bank

erosion

Sedimentation

Water pollution

Related problems in the Mekong delta

In addition: upstream development, climate change-SLR, land

subsidence… 6

2

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UNUSUAL CLIMATE AND HYDROLOGICAL CONDITION IN MEKONG DELTA 2

Unusual climate condition in the South of Vietnam

� High temperature: 35-37 deg., 20ys

� Cool temp.: Dec-Jan 16-17 deg., 10ys.

� High spring tidal during Oct to Feb: 170 cm at Phu An, while previous calculation max WL with P1% 130 cm

� Rain fall distributed infrequent: start earlier some time, (as of 2009, 2010, 2016 P>50mm) and stop later (2006, 2016),

� Continuos High flood 2000 to 2002

� Severely drought: 1998, 2005, 2010, 2012 and typical 2016

� The longest low flood period from 2003-2010, 2012-present

� Typhoons and hurricanes increase in number and intensity: Linda 5 Nov 1997, Durian 17Nov 2006, Nov 2008

� Unusual flow of the Mekong river

Mekong delta flood 2011 Pakhar Storm 1st April 2012

Sources: www.nld.com.vn

Climate change in the Mekong delta

� Sea water level rise about 3 mm/year12

VIETNAM NATIONAL PROJECTION FOR CLIMATE CHANGE AND SEA WATER LEVEL RISE3

3

Biến đổi khí hậu - NBD

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(MONRE 2016)

o RCP4.5:To increase 1,7oc*1,9oc, Rainfall increase 5*15%, SLR 32* 78 cmo RCP8.5:To increase 3,0oc*3,5oc, Rainfall increase >20%, SLR 48*106 cm

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CHANGE OF HYDROLOGICAL FLOW FROM MEKONG RIVER: IMPACT TO FLOOD AND DRY SEASON FLOW

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abnormal operation of hydropower dams

� Abnormal water storage may change a normal hydrological year to a droughty year and opposite way - may resulted from close dam at completed construction, trial operation, other purposes

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3 operated perious of China dams in 2016 .

2: Hydrological change Dry season flow in 2015-2016

China dams operation

2nd times (from 23-28/2/2016)

3th (from

9/3/3016)

1st times (from 19-27/1/2016)

Operation scenario:

early/late water retention

� Early water retention operation may reduce the discharge at early stage of

rainy season, salinity water may happen a longer period

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�Late water retention operation may reduce the discharge at early of dry season, salinity intrusion happen earlier dry season

Late storage water

Early storage water

Natural flow condition

With flow regulation

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SALINITY INTRUSION STATUS5

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Salinity intrusion in dry season 2015-2016

• Potential salinity intrusion (without salinity intrusion control systems) in 2015-2016

• Salinity concentration was too high ����aquaculture cultivation plan is inactively

Source: SIWRR

Salinity concentration was too high, over suitable thresholds for

shrimp cultivation

Orchard areas were affected by saline intrusion to reduce yield product

ProvinceNumber of

family(household)

Number of family lack of drink water

in 2016(household)

Percentage of family lack of

water (%)

Ben Tre 300.000 86.200 28.7

Soc Trang 311.000 43.000 13.8

Kien Giang 415.000 25.000 6

Tra Vinh 244.000 21.400 8.8

Long An 351.000 15.500 4.4

Ca Mau 289.000 14.500 5

Tien Giang 408.000 7.000 1.7

Bac Lieu 209.000 3.200 1.5

Vinh Long 247.000 2.500 1

Hau Giang 182.000 2.500 1.4

Total 220.800 7.5

B�n Tre, Sóc Trăng, Kiên Giang, Trà Vinh… Number of schools,

clinics hotels, factories were also lack of water supply

3: Salinity intrusion In recently period

Affected to drinking water supply in 2016

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CHANGE ON SEDIMENT, RIVERBANK AND COASTAL ZONE EROSION IMPACTS6

TT Scenario Description

Sediment load at Kratie

(Mil ton)Reduction

vs 1998

condition

(%)

Reductio

n vs

present

conditio

n (%)

Max MinAverag

e

1 KB0 Baseline – China dams (CND) 97,0 34,0 59,6 63%

2 KB1 CND+Xayabury 89,3 31,5 54,5 66% 9%

3 KB3CND+ (Pakbeng, Luang

Prabang, Xayabury)81,7 28,4 48,3 70% 19%

4 KB10CND+ 10 mainstream

hydropower dams in Lao PDR58,3 21,3 34,9 78% 42%

5 KB12CND+ 12 mainstream

hydropower dams49,1 17,7 29,4 82% 51%

6 KB12+

CND+ 12 mainstream

hydropower dams+tributaries

dams

29,4 11,1 17,9 89% 58%

Other study (MDS) 13,88 mil tons

4: Change on sediment Impact of upstream development

Sediment change based on some simulation scenario (KC08.13/11-14, SIWRR)

4: Change on sediment Existing of mangrove forest belt

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Lost 500 ha/year

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SEA WATER LEVEL RISE, LAND SUBSIDENCE AND TYPHOONS7

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5: Sea level rice, land subsidence and typhoon

Land subsidence

To what extent? 1.6 – 2.5 cm/year

Delta now faces the twin threats of subsidence and rising sea

levels.

Sinking at rates many times faster than global sea level is rising”.

Sea water level rise (1,6-2cm/year??)

Station PeriodRate of Sea WLR

(mm/year)

Vũng

Tàu1980-2015 4.85

Gành

Hào

1996-2015 16.6

2000-2015 19.6 (2cm/year)

Sông

�c

1996-2015 13.3

2000-2015 11

R�ch

Giá

1996-2015 2.9

2000-2015 5.3

(Na Uy: 1,9 – 2,8 cm/năm) (ICEM: 1,9 –

2,8 cm/năm)

Natinal projection for sea level rise:2100: 100 cm

2030: 17 cm

Max high of wave in KB1 (level 13): 3.5 m

WAVE LEVEL IN TYPHOON

5: Sea level rice, land subsidence and typhoon

Typhoon

e.g: Typhoon wind speed level 13

Distribution of water level rise in high typhoon

KB1 (level 13)

5: Sea level rice, land subsidence and typhoon

Typhoon

e.g: Typhoon wind speed level 13

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IMPACT OF CLIMATE CHANGE TO MEKONG DELTA8

Agriculture and aquaculture development in Mekong delta

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Change of salinity intrusion by

concentration in simulated scenarios

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Change of salinity extent in 1g/lTidal inundation change in SLR scenarios

Flood changes in case of Mekong river

flood as year 2000 + SLRPossible impact of Climate change

and Sea level rise to the Mekong delta

With the pre-simulated results on the impact of

CC&SLR to the Mekong delta it may concluded

that there will be a large change to the natural

conditions (soils - inundated area, water

resources, floods, salinity intrusion, water

quality…), to the ecology conditions (plants,

animals and microorganism, insects…) and

affected to infrastructure, socio-economic and

sustainable development in the Mekong delta.

Posible impact to agriculture in dry season

Evaluation the impact of SLR to Rice cultivation area

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Rice yield reduction and rice

production reduction

Impact

Type of

land use

Affected

area (ha)

Rice yield

reduction (T/ha)

Rice production

reduction (Ton)

Fresh turn to salty 3-rice crops 14180 -6.0 -85081

Brackish turn to salty 3-rice crops 71290 -5.5 -392095

Fresh to brackish 3-rice crops 103135 -1.2 -123762

Brackish to fresh 3-rice crops 77 1.1 84

Salty to brackish 3-rice crops 0 3.5 0

Salty to fresh 3-rice crops 0 5.0 0

Fresh to salty WS-SA 3750 -6.0 -22498

Brackish to salty WS-SA 32891 -5.5 -180899

Fresh to brackish WS-SA 75053 -1.2 -90064

Brackish to fresh WS-SA 4 1.1 4

Salty to brackish WS-SA 0 3.5 0

Salty to fresh WS-SA 0 5.0 0

Fresh to salty WS-SA 40 -6.0 -242

Brackish to salty SA-M 23855 -5.5 -131203

Fresh to brackish SA-M 11848 -1.2 -14217

Brackish to fresh SA-M 0 1.1 0

Salty to brackish SA-M 0 3.5 0

Salty to fresh SA-M 0 5.0 0

Total 336.123 -1.039.973

Posible impact to agriculture in flood season

Impact to bio-diversity

Changes of inundation extent in Cape Camau Park Possible impact to biodiversity (e.g Cape Camau Park)

The living environmental condition for reptiles and

crustaceans is shallow and temporary daily

inundation.

The earned foods for births and other animals are

also come from the similar conditions.

What is happening here?

Impact to infrastructures

� Increase the flooding condition of cities and towns in the delta: Cần Thơ, Mỹ Tho, Bạc Liêu, Long Xuyên...

� Impact to infrastructure of roads and others;

� Impact to current hydraulic structures: the crest of the salinity intrusion gate is about 2.0-2.5m – water would run over the top of sluice gate

� Current dikes and roads would not meet the SLR condition

� ...

Flooding condition in Can Tho city in SLR scenarios

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Flood warning mark

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CONCLUSION AND DELIVERY MESSAGES9

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Inside Mekong delta: Land subsidence/ tidal

inundation/ salinity intrusion/ drought/water

quality…

6: Challenges: Conclusion

Delivery messages

The

Main stream

Mekong hydro�power

cascadesCut

‘Mekong Mekong Mekong Mekong

DragonDragonDragonDragon’

INTO

PIECES

- loss the God’s Gift to Mekong’ people: water with natural flow, protit and fertilizers

- loss the ability to forecast and do early warning for floods and drought. – With reservoir water levels can not predict the real discharge.

Mekong hydropower Cascades cause a considerable losses of sediments, fisheries, agriculture causing drought, salinity intrusion, erosion, environmental problems.

Water resources development in the Mekong basin needs an integrated approach.

Give a hand to save the Mekong River!46