# Landscape Units

A Landscape Unit (LSU) is a collection of HRUs. It can be equivalent to a subbasin, a floodplain or upland unit, or a grid cell with multiple HRUs. LSUs are currently only used for summarizing landscape outputs. Two files are needed to define which HRUs are part of which LSU: 

* [ls\_unit.def](https://swatplus.gitbook.io/io-docs/introduction-1/landscape-units/ls_unit.def) specifies which HRUs a LSU contains.
* [ls\_unit.ele](https://swatplus.gitbook.io/io-docs/introduction-1/landscape-units/ls_unit.ele) lists all HRUs and their corresponding LSU and basin fractions.