Takuro ENDO
Flow Characteristics and Erosion Trends of the Mekong River in the Kingdom of Cambodia

Naoyuki INUKAI

The Mekong River originates from the Tibetan Plateau and flows into the South China Sea in southern Vietnam. In Cambodia, where the river basin covers 85% of the country's area, significant seasonal variations in water flow cause riverbank erosion and slope failures. Additionally, unregulated sand dredging near these areas exacerbates the problem. Understanding current flow conditions and predicting high-risk areas are crucial for effective countermeasures.
This study aims to identify high-risk erosion sites, propose mitigation measures, and assess sediment deposition areas for planned dredging along the Mekong River in Cambodia. Using ADCP measurements of velocity and depth, combined with numerical simulations, the study analyzes riverbed topography, flow patterns, and erosion/deposition trends.
Survey results show that slope failures occur where water depth and velocity are high, and slope angles exceed the critical threshold. These findings help pinpoint high-risk locations for further analysis. Flow simulations were conducted using iRIC software, validating model accuracy by comparing simulated and observed flow rates. The results demonstrated high reproducibility across most cross-sections.
Further simulations examined flow conditions under various discharge scenarios, including annual maximum and minimum flows. All high-risk locations exhibited consistently high velocities near the riverbank, indicating a continuous erosion trend. To mitigate short-term slope failures, structural reinforcements such as concrete blocks should be placed in deeper areas. Additionally, low-velocity zones inside meandering sections and around river islands were identified as suitable dredging sites.
Future research should focus on long-term simulations to assess flow variations over time. This will enable the development of more comprehensive mid-to-long-term slope failure countermeasures and detailed dredging plans, including specific locations and sediment volumes.