> For the complete documentation index, see [llms.txt](https://swatplus.gitbook.io/io-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://swatplus.gitbook.io/io-docs/theoretical-documentation/section-8-water-bodies/sediment-in-water-bodies.md).

# Sediment In Water Bodies

SWAT+ incorporates a simple mass balance model to simulate the transport of sediment into and out of water bodies. SWAT+ defines four different types of water bodies: ponds, wetlands, reservoirs and potholes. Sediment processes modeled in ponds, wetlands, reservoirs, and potholes are identical.

            When calculating sediment movement through a water body, SWAT+ assumes the system is completely mixed. In a completely mixed system, as sediment enters the water body it is instantaneously distributed throughout the volume.