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Data

1. Data description

a. Layer description

In some cases an input item may be defined as either a constant value or more detailed using a Layer based approach. In the latter case you need to create a layer for each input. Then for each specified layer a sub-item will appear where you can specify the input data.

b. Item description

For some items an input item comprises both a spatial distribution and a value that may be time varying.

The spatial distribution of the item can be defined in three ways:

Uniform

The Uniform spatial distribution defines the same value in the entire area. The value can be defined by a constant or by a time-varying dfs0 file.

Station based

If the data is sub area-based the area is divided into a number of sub areas, one for each station. You define the spatial area related to each station by grid codes in a dfs2 file or by polygons in a shape file (.shp). Then for each station a sub-item will appear where you can enter the time series of values for the station.

Fully distributed

If the data is fully distributed you need to specify a dfs2 file with the values to be used.

2. Geometry

Many items in MIKE SHE are defined by a surface elevation. For example, numerical and geologic layers both require bottom surfaces. Some items, such as geologic lenses also require an upper surface. Finally, some items are only defined in parts of the domain, which requires a definition of the areal extent of the parameter.

a. Upper Level

Upper Level
dialogue Type Stationary Real Data
EUM Data Units Elevation or Height above ground

The Upper Level is the upper elevation of the lense or water quality source. It is used by the interpolation algorithm to assign geologic and water quality properties to the model cells.

b. Lower Level

Lower Level
dialogue Type Stationary Real Data
EUM Data Units Elevation or Height above ground

The Lower Level value is used to define the bottom of geologic layers and lenses, numerical layers, and water quality layers and sources.

The bottom of a layer always equal to the top of the layer underneath. However, in the case of lenses and sources, the lower level is used to interpolate geologic and source properties to the model cells. In the case of numerical layers, the lower level is only used when you are using the explicit definition option.

c. Horizontal Extent

Horizontal Extent
Dialogue Type Integer Grid Codes
EUM Data Units Grid Code

Lenses

The horizontal extent is used to define the lateral extents of geologic lenses. The horizontal extent is usually a .shp file polygon, or a dfs2 grid file. In either case, the polygon name or the .dfs2 codes are ignored. Any cell within a polygon or with a grid code different than 0 is treated as part of the lense.

Water Quality Sources

If the source extent is Part Domain, then you can define a local extent for which the larger source file is applied. This allows you to define, for example, a distributed global source file - say of the field scale agricultural inputs in your catchment - and run individual water quality scenarios for each sub-catchment (modelled as a partial extent) to assess the subcatchment contributions to the global stream impact.