The land surface plays a very important role in hydrology. In principle, the land use section is used to define the properties of the land surface. The most important of these is the distribution of vegetation, which is used by MIKE SHE to calculate a the spatial and temporal distribution of actual evapotranspiration.
However, the land surface comes into play in many ways and other sections of the data tree also include properties related to land use. Some of these properties are related to the vegetation distribution, and may even be spatially identical. For example:
Topography - The topography is a physical property of the land surface that defines the hydraulics of both the overland flow and the unsaturated flow. See Topography (V1 p. 41). Related to topography is the definition of Subcatchments (V1 p. 226), which is needed when you are using the Linear Reservoir method for groundwater or the simple, catchment based overland flow method.
Flood zones - In MIKE SHE, flood zones can be defined relative to the MIKE Hydro River branches using Flood codes. For details on how use Flood codes see the chapter on Surface Water (V1 p. 97).
Hydraulic properties - The properties related directly to overland sheet flow are found under Overland Flow (V1 p. 47). This includes the Manning number (V1 p. 267) or surface roughness and the Detention Storage (V1 p. 268), both of which are influenced or even defined by the vegetation.
Hydraulic flow - Areas of the land surface can be hydraulically divided by man-made structures, such as road ways and embankments, which can be defined by Separated Flow Areas (V1 p. 273).
Infiltration properties - The infiltration rate is a property of the soil type, which may be modified by the land use. Related to the gross infiltration rate is the presence or absence of macropores and other soil features leading to rapid infiltration. Both of these properties are found in the Unsaturated Flow (V1 p. 53) section. However, land surface sealing and compaction can be defined as a reduced contact between ponded water and the subsurface. This is defined in the Overland flow section as a Surface-Subsurface Leakage Coefficient (V1 p. 269).
Groundwater drainage - As the groundwater table rises, it intersects low lying topographic features, such as ditches, or other man-made drainage features, such as buried farm drains. These features are related to land use, but are specified as Groundwater drainage (V1 p. 61)
Ponded drainage and Paving - Heavy rainfall will generate ponded areas in the landscape and paving will inhibit infiltration. However, 2D overland flow does not usually travel far. It typically drains into local, small scale ditches and channels. The Ponded Drainage function is used to route local ponded water to urban and natural drainage features. The Ponded Drainage function is calculated before any other function, so it effectively acts on rainfall.