Sedimentation rate estimation in Yangon River for the protection of Yangon Port, Myanmar

The Yangon River is a branch of Ayeyarwady River which is the ninth largest in the world in terms of sediment discharge, depositing more than 330 million tons of sediment annually. Twice daily reversing flows due to the tidal action also make flows in estuaries and tidal section of rivers complex. Yangon Port, located on the Yangon River, is the largest port in Myanmar and it handles about 85% of the country's exports and imports. Waves within the Yangon River do not hinder marine operations but there are two restricted shallow water areas along the navigation channel to Yangon Port called the inner bar (4m water depth) and outer bar (6m water depth). So, the size of the vessel entering to the port is limited by these two shallow water areas. Daily dredging works are required to maintain the depth of navigation channel at shallow water areas. But, even huge amount of dredging works are not enough to maintain the required depth due to the increase rate of sedimentation in Yangon River because of deforestation and riverbank erosion along the river, and it becomes a big issue for Yangon Port. As for an evidence for this erosion, the riverbank shoreline is clearly retreated by comparing topographical map (1904) and google map (2015). The total dredged volume is estimated up to 1.4 million m3/year base on the workload of the dredgers. This is quite a huge volume compared to the other ports in ASEAN countries. Sedimentation rates are estimated based on bedload transport formulas, and the results are compared with observed data measured at 3 locations near the Yangon Port. The results show that the pure sedimentation rate was greater than the rate of sediment removal by dredging, which may cause serious problem for the ship navigation though the channels in the river. Further research is necessary to accurately estimate the sedimentation rate and the to predict future geological changes because the government should consider the other possible ways for the country's exports and imports especially avoiding any huge investment on Yangon Port if it becomes too expensive to maintain the navigation channel