Cambodia-Mekong River Delta Transboundary Aquifer (CMDA)
CMDA

CMDA Technical Methodology - Project Components

The CMDA project applies the GEF International Waters technical methodology, moving from a joint Transboundary Diagnostic Analysis (TDA) to a negotiated Strategic Action Programme (SAP) endorsed by both Cambodia and Viet Nam. This process builds a shared scientific foundation, identifies priority transboundary concerns, and develops coordinated actions for sustainable groundwater management. Supporting components on cooperation, legal reform, capacity building, and gender equality ensure that the methodology is not only technically rigorous but also socially inclusive and politically legitimate. (Source: PRODOC, 2023).

The CMDA project is built on the GEF International Waters (IW) methodology, which has been applied across more than 30 shared river basin and aquifer systems worldwide. As outlined in the Project Document (PRODOC, 2023), this methodology proceeds from a Transboundary Diagnostic Analysis (TDA) to a Strategic Action Programme (SAP). The TDA provides the joint scientific and policy diagnosis of priority issues, while the SAP sets out ministerially endorsed solutions. Complementary components on cooperation, policy reform, and capacity building ensure that these processes are embedded in durable governance frameworks.

Project Area and Geology

The Cambodia–Mekong River Delta Aquifer system extends beneath Cambodia’s Mekong floodplain and the delta in southern Viet Nam. According to the PRODOC (pp. 7–11):

  • The aquifer consists of Quaternary alluvial deposits and deeper Tertiary sedimentary formations, which together act as major transboundary groundwater reservoirs.

  • It supports domestic water supply for millions of people, irrigated agriculture in one of the world’s most productive deltas, and wetlands of international significance.

  • Groundwater is particularly critical in rural Cambodia, where piped supply coverage remains limited and dependence on wells is high.

Main Issues and Pressures

The PRODOC identifies several urgent transboundary issues (pp. 12–17):

  • Over-abstraction and groundwater mining: Viet Nam’s delta provinces pump an estimated 2.5–3 million m³/day, exceeding recharge in many locations. Cambodia’s abstraction is lower in volume but often unmanaged, with little licensing or control.

  • Land subsidence: Linked to groundwater extraction in the delta, with rates of 2–4 cm/year recorded in urban and peri-urban areas. This exacerbates flood risk and damages infrastructure.

  • Saline intrusion: Accelerated by reduced river flows, sea level rise, and declining groundwater levels. Salinity now penetrates tens of kilometers inland in the dry season.

  • Water quality degradation: Arsenic and iron contamination in shallow aquifers, especially in Cambodia, pose risks to drinking water safety. Agricultural and industrial pollution add further pressure.

  • Data and monitoring gaps: Viet Nam has several hundred observation wells, while Cambodia operates fewer than 20, limiting its ability to track groundwater levels or quality (Annex 1).

  • Institutional asymmetry: Viet Nam’s DWRM maintains structured groundwater management policies, while Cambodia’s frameworks remain at an earlier stage of development, creating challenges for harmonization.

These issues underscore the importance of a joint, science-based diagnostic and cooperative management framework — the central purpose of the CMDA project.

Component 1: Joint Science-Based Diagnostic (TDA)
This component produces a Transboundary Diagnostic Analysis (TDA) to establish a shared, evidence-based understanding of the aquifer. Activities include hydrogeological modelling, water balance analysis, ecosystem assessments, and stakeholder consultations.
Outputs include:

  • Baseline assessment of groundwater recharge, abstraction, and storage.

  • Causal chain analysis linking socio-economic drivers (population growth, agriculture, urbanization, climate change) to impacts (subsidence, salinity intrusion, quality degradation).

  • A shared problem tree and set of agreed transboundary priorities.

Findings will provide the foundation for the Strategic Action Programme (SAP, Component 4).

Component 2: Government Pilots
This component translates science into on-the-ground demonstration projects, led by Cambodian and Vietnamese government agencies.
Pilot themes include:

  • Managed Aquifer Recharge (MAR) for water security.

  • Saline intrusion barriers for coastal protection.

  • Water demand management (irrigation efficiency, licensing).

Pilots are co-designed with provincial stakeholders, tested against environmental, social, and economic indicators, and used to ensure that the SAP is not only scientifically robust but also operationally feasible and politically supported .

Component 3: Transboundary Cooperation Mechanisms
Permanent structures for binational governance will be established, including:

  • Harmonized monitoring networks and standards for groundwater and ecosystems.

  • Agreed data exchange mechanisms.

  • A Transboundary Consultation and Coordination Body (TCCB) to oversee SAP implementation, with balanced gender and minority representation .

Component 4: Policy and Legal Reforms
This component focuses on aligning national frameworks with the joint SAP:

  • In Cambodia, supporting enforcement of groundwater licensing and regulatory provisions in the new Environmental Protection and Natural Resources Law.

  • In Viet Nam, strengthening DWRM’s permitting systems and integrating groundwater into basin-level planning.

  • At the regional level, ensuring groundwater is included in Mekong River Commission and ASEAN water cooperation platforms .

It culminates in ministerial endorsement of the Strategic Action Programme (SAP) as a binding roadmap .

Component 5: Capacity Building, Stakeholder Engagement, and Gender Mainstreaming
Activities strengthen institutions and ensure inclusive governance:

  • Training national and provincial staff in hydrogeology, modelling, monitoring.

  • Awareness campaigns with farmers, urban water users, and local authorities.

  • Knowledge-sharing networks linking universities and technical institutes.

A key innovation is integration of UNESCO’s WWAP Gender Toolkit, ensuring:

  • Sex-disaggregated water-use data.

  • Gender-responsive monitoring indicators.

  • Representation of women, Indigenous Peoples, and ethnic minorities in decision-making .

Further Resources on Methodology and Tools

 

The Cambodia–Mekong River Delta Aquifer (CMDA) Project is a Global Environment Facility (GEF) International Waters initiative implemented by the Food and Agriculture Organization of the United Nations (FAO) and led by the International Union for Conservation of Nature (IUCN) as Lead Executing Agency, with UNESCO and MERFI as Executing Partners, in collaboration with the Governments of Viet Nam and Cambodia.

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