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Since 2015.02. Reference to a UGRID NetCDF file that contains only grid geometry meta data. This only supports mesh topologies (unstructured grids) with 2D coordinates. This can be 1D network, 2D triangular, 2D flexible or 3D layered mesh topologies. This currently only works for files that are compliant to the UGRID 1.0 conventions. For more information see httpshttp://ugrid-conventions.github.comio/ugrid-conventions/ugrid-conventions

Irregular grid definition from a UGRID NetCDF file

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To import/export unstructured grid/flexible mesh data in Delft-FEWS, use a timeSeriesImport/ExportRun with type "NETCDF-CF_GRID" or use a generalAdapter import/exportNetcdfActivity. For this to work you need to add an irregular grid definition to the grids.xml configuration file. The easiest way to do this, is by using the option "netcdfFile" (see above) that refers to a NetCDF file that contains a UGRID mesh topology (and no data).

In an unstructured grid the data can be defined either on the nodes, the edges or the faces of the mesh (staggerLocations). Also see http://ugrid-conventions.github.io/ugrid-conventions/#data-defined-on-unstructured-meshes. Each grid definition in grids.xml is valid for only one staggerLocation and this should match the staggerLocation of the data that you are going to import using the grid definition. The staggerLocation on which the data is defined can be deduced from the data variable in a netcdf file that contains the data to import. The data variable (e.g. "water_level") has an attribute called "location" and a dimension (e.g. nmesh2d_face) that both indicate its staggerLocation. In the grid geometry choose the corresponding staggerLocation. If you want to import different data variables that are defined on different staggerLocations in the same mesh, then you will have to create separate grid definitions for different staggerLocations using the same mesh and netcdf file, e.g.:

<irregular locationId="SFBayFM_data_on_faces">
    <netcdfFile>
        <file>sfbay_flowgeom.nc</file>
        <geoDatum>UTM10N</geoDatum>
        <meshTopologyVariableName>mesh2d</meshTopologyVariableName>
        <staggerLocation>face</staggerLocation>
    </netcdfFile>
</irregular>
<irregular locationId="SFBayFM_data_on_nodes">
    <netcdfFile>
        <file>sfbay_flowgeom.nc</file>
        <geoDatum>UTM10N</geoDatum>
        <meshTopologyVariableName>mesh2d</meshTopologyVariableName>
        <staggerLocation>node</staggerLocation>
    </netcdfFile>
</irregular>

It is possible to use a D-Flow flexible mesh (D-Flow FM) flowgeom UGRID NetCDF file, produced by a D-Flow FM model run, as grid definition in Delft-FEWS. If your D-Flow FM model run does not produce a flowgeom file, then add the following line in the D-Flow FM .mdu file in the output section, e.g.:

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The flowgeom file format will match the configured map file format. If MapFormat is not set to 4, then D-Flow FM will produce a valid UGRID file. With MapFormat set to 1 it will produce a format that looks very much like UGRID, but is not the same. Delft-FEWS cannot use the produced flowgeom filecan only use valid UGRID files. Using MapFormat 1 files with Delft-FEWS may cause problems.

Config Examples

<irregular locationId="meshLocation">
	<netcdfFile>
		<file>simplebox_hex7_map.nc</file>
		<meshTopologyVariableName>insert_mesh_variable_name_here</meshTopologyVariableName>
		<staggerLocation>face</staggerLocation>
	</netcdfFile>
</irregular>

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