Rivers carry sediment down their riverbeds, allowing for the formation of depositional features such as river deltas, alluvial fans, braided rivers, oxbow lakes, levees and coastal shores. The construction of a dam blocks the flow of sediment downstream, leading to downstream erosion of these sedimentary depositional environments, and increased sediment build-up in the reservoir.
While the rate of sedimentation varies for each dam and each river, eventually all reservoirs develop a reduced water-storage capacity due to the exchange of "live storage" space for sediment. Diminished storage capacity results in decreased ability to produce hydroelectric power, reduced availability of water for irrigation, and if left unaddressed, may ultimately result in the expiration of the dam and river.

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Additionally, the build-up of sediment in reservoirs can have negative impacts on water quality as it can trap pollutants and nutrients, leading to the degradation of water quality and ecosystems downstream. This can have significant environmental and economic consequences for communities that rely on the river for drinking water, agriculture, and recreation.

To mitigate these impacts, sediment management strategies can be implemented, such as dredging sediment from reservoirs, releasing sediment downstream in controlled intervals, or constructing bypass channels to allow sediment to bypass the dam. These strategies can help maintain the functionality of the dam and restore the ecological balance of the river system.

It is important for dam operators and policymakers to consider the long-term effects of sedimentation on river systems when planning and managing dams. By implementing sustainable sediment management practices, we can ensure the longevity and effectiveness of dams while preserving the health of our rivers and ecosystems.