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How do marshes and floodplains affect the lower Amur River?

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Topographic map of the Amur River basin and its drainage network, covering parts of northeastern China, eastern Russia, Mongolia, and North Korea. The map uses color shading to indicate elevation, shows major rivers and tributaries, surrounding mountain ranges, swamps, marshes, and lakes, and includes a locator inset of the region within Asia. Major cities, railways, and dams are also marked. — Amur River The Amur River basin and its drainage network.

In the lower reaches of the Amur River, broad marshlands and floodplains play a significant role in regulating the river's hydrology. By capturing excess floodwaters, these areas help dampen the dramatic water level variations that occur in the river's narrower upstream channels.1

During high-water seasons, the river overflows onto the flat, marshy ground of the valley, transforming the region into an enormous lake. In these sections, the riverbed expands into a complex labyrinth of branches, channels, islands, and sandbanks. Because these marshlands absorb and spread out the flow, the maximum rise in water level near the river's mouth is significantly reduced, reaching only about 8 feet (2.5 metres) compared to the much higher fluctuations seen upstream.21