United Nations Water (UN Water) defines transboundary waters as the aquifers, and lake and river basins shared by two or more countries. Nearly half of the Earth's land surface is occupied by 263 transboundary lakes which provide 60 percent of global freshwater flow on which 2 billion people worldwide depend on. To be exact, the global total surface area for transboundary aquifer is 26,561,572 km2, those for transboundary lake is 874,171 km2, those for transboundary river basin is 62,000,000 km2, those for large marine ecosystems is 113,000,000 km2 and those for open ocean is 232,000,000 km2 according to Transboundary Waters Systems – Status and Trends Crosscutting Analysis (Vol: 6) of Transboundary Water Assessment Programme published by the United Nations Environment Programme (UNEP) in January 2016.
Depleted and degraded transboundary water supplies can bring social unrest and spark conflict within and between countries through which water flows. For example, building a dam upstream by a country can drastically reduce a river's flow downstream in another country. Since 1948, there have been many incidents of conflict over water. Therefore, to prevent these conflicts, Integrated Water Resource Management, which creates benefits for everyone; international trade, climate change adaptation, economic growth, food security, improved governance and regional integration, should be implemented to boost food and energy production, reduce poverty and control rural-urban migration.
The Mekong is also the Transboundary River with a length of approximately 5,000 km in East and Southeast Asia flowing from China to Vietnam running through Myanmar, Laos, Thailand, and Cambodia. It is the twelfth longest in the World and sixth longest river in Asia. The River is a transboundary resource of significant socio-economic, environmental, and cultural value. It provides a vital lifeline for millions of people living in the basin by supporting irrigation, energy production and ecosystem conservation.
Currently the Mekong River Basin is facing some issues: Change in long-term flow regime and Rapid water level fluctuation in water flow conditions, Reduced sediment transport in Water quality and sediment conditions, Loss of wetlands and Fish populations in Status of environmental assets, Inequality of access to Household food and water security in Living conditions and wellbeing, Temperature increases and more severe floods and droughts in Climate trends and extremes.
Governing the Mekong River requires coordinated management approaches, dialogue, and cooperation not only between sectors but also between countries to achieve a well-balanced development of the basin. The Integrated Water Resource Management (IWRM) process is relevant for large and complex rivers such as the Mekong River Basin where water, fish, sediment, and other valuable resources all travel from one country to the next, and the transboundary river's ecosystems are highly connected.
Since 2009, Mekong River Commission (MRC), an intergovernmental organization for regional dialogue and cooperation in the Lower Mekong River Basin, established in 1995 based on the Mekong Agreement between Cambodia, Lao PDR, Thailand and Viet Nam, initiated the Mekong IWRM Project (M-IWRMP). Five joint bilateral projects were launched under this project in 2013-2014 to address transboundary issues in the management of water and related resources for sustainable development through the IWRM approaches.
- Sesan and Srepok River Basins Water Resources Management Project (2014-2019) assisted Cambodia and Vietnam to institutionalize bilateral mechanisms to address major issues putting pressure on the sub-basins. These issues included hydropower and irrigation developments that cause social and environmental impacts such as soil erosion, deterioration of watersheds, increased flash floods, and degradation of water quality.
- Mekong and Sekong Rivers Fisheries Management Project (2014-2019) helped improve fisheries management in the bordering provinces of Stung Treng and Kratie in Cambodia and Champasak and Attapeu in Lao PDR and supported the two countries to establish a joint fishery monitoring system and a fisheries management action plan.
- Mekong Delta Water Resources Management Project (2014-2019) supported Cambodia and Vietnam to analyze issues that threatened the basin's sustainability, such as flooding, drought, acid sulphate soils, and saltwater intrusion and promoted cooperation on the development of data and information sharing mechanisms and basin monitoring strategies for harmonized water resources management and future investment in the Mekong Delta.
- Xe Bang Hieng and Nam Kam River Basins Wetland Management Project (2013-2018) strengthened to improve wetland management in Lao PDR's Xe Bang Hieng and Thailand's Nam Kam river basins and enhanced IWRM-based management practices to support river basin planning, flood management, and sustainable irrigation development.
- Tonle Sap and Songkhla Lake Basins Communication Outreach Project (2013-2018) promoted good governance of Cambodia's Tonle Sap and Thailand's Songkhla Lakes for sustainable livelihoods through community outreach activities and knowledge exchange.
Building on the success of the above five joint bilateral projects, MRC identified a new set of five joint projects in Lower Mekong Basin (LMB) 2016-2020 to facilitate sustainable development of the Mekong Basin through many sectors, such as food, energy, navigation, tourism, and flood protection.
- Lao-Thai safety regulations for navigation (Thailand, Lao PDR)
- Cross-border water resources development and management, including environmental impact monitoring of the Don Sahong hydropower project (Lao PDR, Cambodia)
- Transboundary cooperation for flood and drought management in the Thai-Cambodian border area – a part of the 9C-9T sub-area (Thailand, Cambodia)
- Sustainable water resources development and management in the Sekong, Sesan and Srepok river basins (3S Basin) (Viet Nam, Cambodia, Lao PDR)
- Integrated flood management in the border area of Cambodia and Vietnam in the Mekong Delta for water security and sustainable development (Viet Nam, Cambodia)
Also, MRC established the IWRM-based Basin Development Strategy (BDS) for the Mekong River Basin 2021-2030. The BDS 2021–2030 is prepared and agreed for a ten-year period and focuses on the entire Mekong River Basin. The BDS 2021–2030 guides all relevant actors involved in Mekong water-related issues towards achieving improvements in the environmental, social, and economic state of the Mekong River Basin.