End of Basin issues in Mekong Basin

• Issues facing those living in Tonle Sap /Delta • Bio-physical causes /origins of these problems• Who is affected? • What are their long-term development

objectives?

Issues facing those living in Tonle Sap/Delta

• Natural resource degradation– Declining fish population – Salinity intrusion and acidity– River bank erosion– Sedimentation– Imbalance water flow in dry and wet season

• Water shortage in dry season– Competing demand for water

• Flood and inundation• Deforestation

Seawater Intrusion in Mekong Delta (2/3)Seawater Intrusion in Mekong Delta (2/3)Jan. 2003Upstream Discharge into

Mekong Delta is Key Factor !

Upper Limit of Maximum Salinity in 1985

20g/l

25g/l

0g/l 5g/l10g/l15g/l

April

0g/l5g/l10g/l

June

Flood and inundation

Tidal effect at Delta

0.8 m above sea

Flood-Hazard Areas in the Lower Mekong Basin

Issues facing those living in Tonle Sap/Delta

• Natural resource degradation– Declining fish population – Salinity intrusion and acidity– River bank erosion– Sedimentation– Imbalance water flow in dry and wet season

• Water shortage in dry season– Competing demand for water

• Flood and inundation• Deforestation

24

Despite being heavily forested, deforestation rate in Cambodia is at present very high. In 1989-92, it reached almost 3% per year.

Forest clearance in Viet Nam has resulted in severe soil erosion and an increased incidence of floods as many upper watersheds areas have been cleared.

Deforestation

Bio-physical causes / origins of these problems

• Population pressure • Development interventions • Over-fishing • Increasing water demand in sector

development • Increasing use of chemicals• Change of hydrological regime • Climate change• Deforestation

Who is affected?

• All people in the sub-areas (directly and indirectly)

• The ecology in the sub-area

• The biodiversity in the sub-area

What are the long-term development objectives of those at the end of the Basin system?

• Economic growth

• Poverty alleviation

• Prosperous and peaceful basin

• Mutual benefit and understanding, and cooperation

Irrigation growthIrrigation growthTotal dry season irrigated cropped areasirrigated cropped areas (ha)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

mill

ion

hect

ares

1985 1990 1995 2000

Cambodia Lao PDR Thailand Viet Nam

Indicative dry season water balanceAverage Flows at Kratie

MCM/month

-

20,000

40,000

60,000

80,000

100,000

120,000

J F M A M J J A S O N D

Dry Season Water Balance MCM

-

25,000

50,000

75,000

100,000

125,000

150,000

1985 2000Dry season runoff Irrigation 90 Irrigation 70

On average 10,400 MCM/month in dry

season

13-17%13-17% of Kratie flow

52%52%

Basin irrigation efficiencies of 90%90% and 70%70%

40%40%

9

Mekong Fisheries

Total 2 million tonnes Capture Fisheries

1.75 million tonnes Aquaculture 0.25 million

tonnes

Total value: $1,400 million

40 million people involved full or part-time

Non-fish products (shellfish, frogs, insects, aquatic plants)

Flooding

• 2000 flood– 800 people died– $400 million damage

• 2002 flood and drought– impact on food security

and health

Key Factor of Water Utilization in Mekong DeltaKey Factor of Water Utilization in Mekong Delta

Fishery

Water Utilization inMekong Delta

Agriculture

Navigation Domestic

Vital Role of Mekong Deltain Vietnam Economy :

39,000 km2, 6.4% of LMRB 16 millions of population Huge potential of agriculture (2.9

million ha, 74% of delta) Irrigated for paddy (1.4 million ha) More than half of paddy

production

Key Issues on Water Use inMekong Delta:

Water Shortage in the Dry Season Seawater Intrusion Acidification (acid sulphate soils)

HydrologicalCharacteristics in Mekong

Delta (see next picture)

Changes in overall paddy areas and production - 1990 to 2000

80%80%

60%60%

40%40%

20%20%

ProductionArea

Cambodia Lao PDR Thailand Viet NamCambodia Lao PDR Thailand Viet Nam