Why do ports on the Irrawaddy River need separate high-water and low-water landing points?

Ports on the Irrawaddy River require separate high-water and low-water landing points due to the river's extreme seasonal fluctuations in water level. These variations are driven primarily by monsoon rains occurring between May and October, as well as the rapid melting of snow and glaciers during the summer months.1

The difference between the lowest and highest water levels is significant; for example, records at Mandalay and Prome have shown annual variations of approximately 31.7 feet (9.66 metres) and 37.3 feet (11.37 metres), respectively. During the period from mid-June to mid-October, the river typically rises 20 to 30 feet (6 to 9 metres) above its lowest level, which occurs in February. Consequently, these distinct landing points are necessary to ensure that vessels can safely dock and load or unload cargo regardless of the river's current stage.1