# Wetlands

Wetlands are HRUs in which ponding of water on the surface is allowed. There are two files that are specific to wetlands:

* Main wetland file: [**wetland.wet**](https://swatplus.gitbook.io/io-docs/introduction-1/wetlands/wetland.wet)
* Wetland hydrology: [**hydrology.wet**](https://swatplus.gitbook.io/io-docs/introduction-1/wetlands/hydrology.wet)

For defining the remaining wetland properties, the following reservoir files are used: 

* Wetland initialization: [**initial.res**](https://swatplus.gitbook.io/io-docs/introduction-1/reservoirs/initial.res)
* Wetland sediment: [**sediment.res**](https://swatplus.gitbook.io/io-docs/introduction-1/reservoirs/sediment.res)
* Wetland nutrients: [**nutrients.res**](https://swatplus.gitbook.io/io-docs/introduction-1/reservoirs/nutrients.res)
* Wetland release: [**res\_rel.dtl**](https://swatplus.gitbook.io/io-docs/introduction-1/decision-tables/lum.dtl)