The Mekong River is one of the most important transboundary rivers of Asia. It flows through or along six countries: China, Myanmar, Laos, Thailand, Cambodia and Vietnam. In China, the upper part of the river is called the Lancang Jiang. After entering mainland Southeast Asia, it is known as the Mekong. The river is central to the geography, economy, ecology and geopolitics of mainland Southeast Asia.
Course
The Mekong originates in the Tibetan Plateau and flows southwards through China’s Yunnan province before entering Southeast Asia.
It then passes through:
- Myanmar
- Laos
- Thailand
- Cambodia
- Vietnam
Finally, it drains into the South China Sea through the Mekong Delta in Vietnam.
The river is nearly 4,900 km long, making it one of Asia’s major river systems.
Basin Importance
The Mekong basin supports one of the world’s most productive river ecosystems.
It is important for:
- rice cultivation
- fisheries
- inland navigation
- hydropower
- wetlands
- floodplain agriculture
- drinking water
- biodiversity
- livelihoods of millions of people
The lower Mekong basin is especially important for Cambodia and Vietnam because it supports food security, fisheries and delta agriculture.
Major Tributaries
Important tributaries and sub-basins include:
- Nam Ou
- Nam Ngum
- Mun River
- Chi River
- Tonle Sap system
- Sekong
- Sesan
- Srepok
The Tonle Sap Lake in Cambodia is especially significant because it is connected to the Mekong through a unique seasonal flow reversal system. During the monsoon, Mekong floodwaters flow into Tonle Sap, expanding the lake and supporting one of the world’s richest inland fisheries.
Mekong Delta
The Mekong Delta in Vietnam is one of Asia’s most important agricultural regions.
It supports:
- rice cultivation
- aquaculture
- fisheries
- fruit production
- dense rural settlements
- inland waterways
- export-oriented agriculture
The delta is often described as Vietnam’s rice bowl. However, it is increasingly threatened by sea-level rise, salinity intrusion, sediment reduction, sand mining, upstream dams and climate change.
Economic Significance
The Mekong supports both traditional and modern economic activities.
- Fisheries provide food and livelihoods for millions.
- Floodplain agriculture supports rice and vegetable production.
- Hydropower projects supply electricity, especially in Laos and China.
- Navigation supports regional trade.
- Wetlands support biodiversity and local livelihoods.
- The delta supports major agricultural exports from Vietnam.
The river is therefore not just a water source; it is an economic lifeline for mainland Southeast Asia.
Hydropower and Dams
Hydropower is one of the most controversial issues in the Mekong basin.
China has built several large dams on the upper Lancang-Mekong. Laos has also pursued large hydropower projects as part of its strategy to become the “battery of Southeast Asia.”
Dams create electricity and revenue, but they also affect:
- river flow
- sediment transport
- fish migration
- flood pulses
- agriculture
- delta stability
- downstream livelihoods
A key concern is that upstream dams can alter the natural seasonal rhythm of the Mekong, which is essential for fisheries and floodplain agriculture.
Mekong River Commission
The Mekong River Commission is the main intergovernmental body for cooperation in the lower Mekong basin.
Its members are:
- Cambodia
- Laos
- Thailand
- Vietnam
China and Myanmar are not full members; they are dialogue partners. The MRC supports basin-wide planning based on Integrated Water Resources Management and works on fisheries, agriculture, navigation, hydropower, flood and drought management, climate change and ecosystem protection.
This membership gap is important because China controls the upper basin but is not a full member of the MRC.
China and Lancang-Mekong Cooperation
China leads a separate mechanism called the Lancang-Mekong Cooperation. It includes China, Cambodia, Laos, Myanmar, Thailand and Vietnam.
This mechanism gives China a more direct role in Mekong affairs. The MRC Secretariat has observer status in the LMC’s water-resources working group, allowing some degree of information sharing and coordination.
However, tensions remain because downstream countries depend heavily on upstream flow, while China controls major dams in the upper basin.
Environmental Concerns
The Mekong faces serious ecological pressure.
Major concerns include:
- hydropower dams
- reduced sediment flow
- overfishing
- sand mining
- wetland loss
- pollution
- climate change
- salinity intrusion in the delta
- loss of fish biodiversity
A 2024 report by WWF and conservation partners found that around 19% of assessed Mekong fish species are threatened with extinction. The report identified dams, habitat loss, wetland conversion, sand mining, invasive species and climate change as major threats.
This is important because the Mekong is one of the world’s richest inland fisheries. Ecological decline directly affects food security and livelihoods.
Climate Change Concerns
Climate change is increasing stress on the Mekong basin.
Likely impacts include:
- irregular monsoon rainfall
- stronger droughts
- intense floods
- sea-level rise in the delta
- salinity intrusion
- reduced agricultural productivity
- pressure on fisheries
- higher uncertainty in dam operations
The MRC’s State of the Basin Report 2023 focuses on the basin’s environment, economy, society, climate change and cooperation challenges, showing that climate and hydropower issues are now central to Mekong governance.
India and the Mekong
India engages with Mekong countries through the Mekong-Ganga Cooperation, established in 2000.
It includes:
- India
- Cambodia
- Laos
- Myanmar
- Thailand
- Vietnam
The cooperation is based on civilisational links between the Ganga and Mekong regions and focuses on culture, tourism, education, transport, connectivity and people-to-people ties.
For India, the Mekong region is important because it connects with:
- Act East Policy
- ASEAN engagement
- India-Myanmar-Thailand connectivity
- cultural diplomacy
- maritime and land connectivity
- balancing China’s influence in mainland Southeast Asia
Strategic Importance
The Mekong region is strategically important because it lies between India, China and ASEAN.
It matters for:
- China’s influence in mainland Southeast Asia
- India’s Act East Policy
- ASEAN connectivity
- supply-chain diversification
- regional river diplomacy
- food and water security
- infrastructure competition
- Indo-Pacific geopolitics
China’s role through dams, financing and Lancang-Mekong Cooperation has made the river a strategic issue, not just an environmental one.
Key Challenges
- China’s upstream control over river flow
- incomplete membership of the Mekong River Commission
- hydropower impact on fisheries and sediment
- climate change and droughts
- salinity intrusion in Vietnam’s delta
- food-security risks from fish decline
- sand mining and riverbank erosion
- weak enforcement of transboundary environmental norms
- competing needs of energy, agriculture and ecology
- strategic competition between China and other regional actors
Way Forward
The Mekong needs stronger basin-level cooperation based on transparent data sharing, ecological protection and sustainable development.
Priority areas include:
- real-time sharing of dam-release and water-flow data
- stronger role for the Mekong River Commission
- environmental assessment of hydropower projects
- protection of fish migration routes
- reduction of sand mining
- wetland conservation
- climate-resilient delta planning
- cooperation between MRC and Lancang-Mekong Cooperation
- stronger livelihood protection for fishing and farming communities
India should strengthen the Mekong-Ganga Cooperation by linking cultural diplomacy with practical projects in connectivity, digital public infrastructure, education, water management and capacity building.
Conclusion
The Mekong is one of Asia’s most important transboundary rivers. It sustains agriculture, fisheries, hydropower, biodiversity and livelihoods across mainland Southeast Asia.
Its future depends on whether the basin can balance development with ecological security. Hydropower, climate change, China’s upstream role and delta vulnerability have made the Mekong a critical issue in Southeast Asian geopolitics and environmental governance.
