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Why does the Indus River deposit silt across the plains of Pakistan?

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Physical map showing the Indus River basin and its drainage network across parts of Pakistan, India, China, and Afghanistan. The map details river courses, tributaries, canals, dams, irrigated and marsh areas, sand regions, and elevation changes with shaded relief. International, disputed, and control boundaries are marked, and a small locator map in the corner shows the basin's position within South Asia. — Indus River The Indus River basin and its drainage network.

The Indus River deposits silt across the plains of Pakistan primarily because its flow slows down significantly as it moves across the flat landscape.1

As the river traverses the plains, its reduced velocity diminishes its capacity to transport sediment, causing it to deposit accumulated silt on its bed. Over time, this process of aggradation has built up the riverbed, often raising it above the level of the surrounding sandy plains. Much of the land in the Sindh province has been formed by this alluvium, which the river has laid down over time. While embankments and levees have been constructed to manage the river and prevent flooding, the alluvial nature of the soil means these structures can occasionally give way, leading the river to shift its course.12