# 4. Results 3Di¶

The results of a simulation are written to file. The result file is created using NetCDF, which is a set of software libraries and self-describing, machine-independent data formats that support the creation, access, and sharing of array-oriented scientific data. The set of libraries can be used by multiple tools and programming languages, such as matlab, python and excel, to extract the data from the netcdf data formats.

The 3Di Plugin visualizes the information stored in this file. An overview of the data format in the output file is given in this chapter, to help users in reading data from file. To facilitate users in the direct access to the results from the output file, users can make use of the python package *threedigrid*. Which can be downloaded from https://pypi.org/project/threedigrid. This package helps to link the output data to the input data.

During the spring release of 2018 the output file has been changed. The changes include a change in name from *subgrid_map.nc* to *results_3di.nc* and changes to the data format within the output file. An overview of both data formats is presented below.

These files consist of all relevant variables that are necessary to analyze the results of a simulation. The user defines the output time step. The snapshots of the flow are saved at these intervals. Note, that the output time step in combination with the size of the model will define the size of the output file. In addition to these snap shots, 3Di can generate aggregated results. More about this can be found in Aggregated output.

## 4.1. Data format *results_3di.nc*¶

The current output NetCDF file consists of all flow variables of the 1D and the 2D mesh. The results file is constructed according to the CF Conventions . In this data format, the 2D and 1D mesh are split, so each part of the mesh has its own result and mesh variable. A description of all the flow and mesh variables for the 1D and 2D mesh are given below.

For the results in the 1D and in the 2D domain, results are split between node and line variable. Node variables are typically, variables related to volumes. This concens volumes, water levels and all the source and sink terms. Line variables are related to flow variables, in other words velocities and discharges. This distiction is also clear in the 3Di Plugin and in the contsruction of the result files.

### 4.1.1. 2D Mesh Cell/Node variables:¶

First the meta information of the computational grid is defined.

**Coordinates**

Mesh2DFace_xcc: x-coordinate of the center of the computational cell

Name: Flow Face 2D center x coordinate

Unit: [m]

Mesh2DFace_ycc: y-coordinate of the center of the computational cell

Name: Flow Face 2D center y coordinate

Unit: [m]

Mesh2DFace_zcc: The deepest point in either the surface water cell or the groundwater cell

Name: Flow Face 2D center z coordinate

Unit: [m MSL]

Mesh2DContour_x: x-coordinates of the location of the edge of the cell

Name: List of x-coordinates forming Face

Unit: m

Mesh2DContour_y: y-coordinates of the location of the edge of the cell

Name: List of y-coordinates forming Face

Unit: m

**Attributes** Some administrative information

Mesh2DNode_id: IDfrom the computational core

Name: Node Identifier

Mesh2DFace_sumax: Maximum surface area in a computational cell

Name: Total cell surface

Unit: m2

Mesh2DNode_type: Type of 2D computational cell

Name: Type of 2D mesh node/face

Types: surface_water_2d, grounwater_2d, groundwater_2d, open_water_boundary_2d, groundwater_boundary_2d

**Dimensions** Lenght of the arrays

nMesh2D_nodes:

Name: Number of 2D mesh nodes/faces.

**Flow Variables** These are the variable that are defined in the cell centers.

Mesh2D_s1: Water level, depending on the node type, it is the surface or the groundwater level.

Name: waterlevel

Unit: m MSL

Mesh2D_vol: water volume in a cell

Name: Water volume

Unit: m3

Mesh2D_su: current wet surface area

Name: Wet surface area

Unit: m2

Mesh2D_ucx: Interpolated flow velocity in the cell center in x-direction

Name: Flow velocity in x direction in cell center

Unit: m/s

Mesh2D_ucy: Interpolated flow velocity in the cell center in y-direction

Name: Flow velocity in y direction in cell center

Unit: m/s

Mesh2D_rain: Current amount of rain in computational cell

Name: Rain

Unit: m3/s

Mesh2D_q_lat: Point discharge in computational cell

Name: Lateral discharge

Unit: m3/s

Mesh2D_infiltration_rate_simple: Current amount of infiltration in computational cell

Name: Infiltration rate

Unit: m3/s

Mesh2D_leak: Current amount of leakage in computational cell.

Name: Leakage rate

Unit: m3/s

Mesh2D_intercepted_volume: Amount of intercepted volume

Name: intercepted_volume

Unit: m3

Mesh2D_q_sss: Current amount of surface sources and sinks discharge in computational cell.

Name: Surface sources and sinks discharge

Unit: m3/s

### 4.1.2. 2D Mesh Line variables:¶

The meta information, that defines the structure for the line variables is mentioned first.

**Coordinates**

Mesh2DLine_xcc:

Name: Flow line 2D center x coordinate.

Unit = m

Mesh2DLine_ycc:

Name: Flow line 2D center y coordinate.

Unit = m

Mesh2DLine_zcc:

Flow line 2D center z coordinate.

Unit = m

**Attributes**

Mesh2DLine_type:

Name: Type of Cell edge

Types: open_water_2d, open_water_obstacles_2d, vertical_infiltration_2d, groundwater_2d, open_water_boundary_2d, groundwater_boundary_2d

**Dimensions**

nMesh2D_lines:

Name: Number of 2D Mesh lines.

**Flow variables**

Mesh2D_u1: This variable, in case of Horton-based infiltration and groundwater flow, also consists of the vertical flow and the groundwater flow. This depends on the Line Type. This also yields for most of the other line variables.

Name: Flow velocity on 2D flow line

Unit: m/s

Mesh2D_q:

Name: Discharge on flow line

Unit: m3/s

Mesh2D_au:

Name: Wet cross-sectional area

Unit: m

Mesh2D_up1:

Name: Flow velocity in interflow layer

Unit: m/s

Mesh2D_qp:

Name: Discharge in interflow layer

Unit: m/s

### 4.1.3. 1D Mesh Node variables:¶

The results for the 1D variables are structured in a similar way. Note that embedded nodes do not have a 1D water level, volume etc information. This information can be found in the 2D results.

**Coordinates**

Mesh1DNode_xcc:

Name: Node 1D x coordinate

Unit: m

Mesh1DNode_ycc:

Name: Node 1D y coordinate

Unit: m

Mesh1DNode_zcc:

Name: Node 1D z coordinate

Unit: m MSL

**Attributes**

Mesh1DNode_id:

Name: Node Identifier

Mesh1DNode_sumax:

Name: Total cell surface

Unit: m2

Mesh1DNode_type:

Types = node_without_storage_1d, open_water_with_storage_1d, open_water_boundary_1d

**Dimensions**

nMesh1D_nodes:

Name: Number of 1D mesh nodes

**Node variables**

Mesh1D_s1: Waterlevel in 1D Node

Name: Waterlevel

Unit: m MSL

Mesh1D_vol: Water Volume in a cell

Name: Water volume

Unit: m3

Mesh1D_su: Current wet surface area

Name: Wet surface of 1D Node

Unit: m2

Mesh1D_rain: Inflow in 1D from rain or dry wetter discharge

Name: Inflow in 1D from rain

Unit = m3/s

Mesh1D_q_lat: Point source/sink flux in 1D cell

Name: Lateral discharge in/from 1D cell

Unit = m3/s

### 4.1.4. 1D Mesh Line variables:¶

**Coordinates**

Mesh1DLine_xcc:

Name: Flow line 1D x center coordinate

Unit: m

Mesh1DLine_ycc:

Name: Flow line 1D center y coordinate

Unit: m

Mesh1DLine_zcc:

Name: Flow line 1D z center coordinate

Unit = m MSL

**Attributes**

Mesh1DLine_id:

Name: Line identifier

Mesh1DLine_type:

Types: embedded_1d, isolated_1d, connected_1d, long_crested_structure_1d, short_crested_structure_1d, double_connected_1d, from_node_with_storage_1d2d, from_node_without_storage_1d2d, potential_breach_1d2d, groundwater_1d2d, boundary_1d

**Dimensions**

nMesh1D_lines:

Name: Number of 1D Mesh lines

**Flow variables**

Mesh1D_u1:Flow velocity on 1D flow line, including 1D2D connections.

Name: Flow velocity on 1D flow line

Unit: m/s

Mesh1D_q:

Name: Discharge on 1D flow line

Unit: m3/s

Mesh1D_au:

Name: Wet cross-sectional area

Unit: m

Mesh1D_breach_depth:

Name: Breach depth on 1D2D connection

Unit: m

Mesh1D_breach_width:

Name: Breach width on 1D2D connection

Unit: m

### 4.1.5. Pump variables:¶

**Coordinates**

Mesh1DPump_xcc:

Name: Start point Pump 1D x-coordinate

Unit: m

Mesh1DPump_ycc:

Name: Start point Pump 1D y-coordinate

Unit: m

**Attributes**

Mesh1DPump_id:

Name: Pump identifier

**Dimensions**

nPumps:

Name: Number of 1D pumps

**Flow variables**

Mesh1D_q_pump:

Name: Pump discharge

Unit: m3/s

## 4.2. Data format *subgrid_map.nc*¶

In the file called: subgrid_map.nc exists the following information:

X-coordinates of the 2D computational cell corner points (FlowElemContour_x)

size[4,n2dtot]

dimension [m]

Y-coordinates of the 2D computational cell corner points (FlowElemContour_y)

size [4,n2dtot]

dimension [m]

X-coordinates 1D en 2D computational cell center point (FlowElem_xcc)

size [number of computational nodes]

dimension [m]

y-coordinates 1D en 2D computational cell center point (FlowElem_ycc)

size [number of computational nodes]

dimension [m]

Maximum surface area computational cell (sumax)

size [number of computational nodes]

dimension [m2]

Connections between computational points in 1D network (FlowLine_connections)

size [2,number of flow lines]

dimension [-]

Connections by a pump (PumpLine_connections)

size [2,number of pumps]

dimension [-]

(projected_coordinate_system (projected_coordinate_system)

size [1]

dimension [-]

Deepest point of a computational cell (bath)

size [number of computational nodes]

dimension [m MSL]

Potential breaches

size [number of potential breaches]

dimension [-]

Mapping of input and out put of connection nodes (node_mapping)

size [2,number of connection nodes]

dimension [-]

Mapping of input and out put of connection lines (channel_mapping)

size [2,number of flow lines]

dimension [-]

Time (time)

size [number of time steps]

dimension [s]

Water level (s1)

size [number of computational nodes]

dimension [m MSL]

Volume in a computational cell (vol)

size [number of computational nodes]

dimension [m3]

Wet surface areas computational cell (su)

size [number of computational nodes]

dimension [m2]

Velocity interpolated in cell centre in x-direction (ucx)

size [number of computational nodes]

dimension [m/s]

Velocity interpolated in cell centre in y-direction (ucy)

size [number of computational nodes]

dimension [m/s]

Rain per computational cell (rain)

size [number of computational nodes]

dimension [m3/s]

Lateralen per computational cell (qlat)

size [number of computational nodes]

dimension [m3/s]

Infiltration per computational cell (infiltration)

size [n2dtot]

dimension [m3/s]

Velocity (u1)

size [number of flow lines]

dimension [m/s]

Discharge (q)

size [number of flow lines]

dimension [m3/s]

Wet Cross-Sectional area (au)

size [number of flow lines]

dimension [m2]

Velocity in interflow layer (up1) (if defined)

size [number of flow lines]

dimension [m/s]

Discharge in interflow layer (qp) (if defined)

size [number of flow lines]

dimension [m3/s]

Discharge (q_pump)

size [Number of pumps]

dimension [m3/s]

computational cells in 2D (nFlowElem2D)

[n2dtot]

computational cells in 1D (nFlowElem1D)

[n1dtot]

computational cells concerning 2D boundary conditions (nFlowElemBound2d)

[n2dobc]

computational cells concerning 1D boundary conditions (nFlowElemBound1d)

[n1dobc]

total computational cells (nFlowElem)

[number of computational nodes]

Flowlines in 2D Domain (nFlowline2D)

[l2dtot of liutot+livtot]

Flowlines in 1D Domain (nFlowline(1D)

[l1dtot]

1D2D Connections (nFlowline1D2D)

[infl1d]

Flowlines concerning 2D boundary conditions (nFlowline2DBound)

[n2dobc]

Flowlines concerning 1D boundary (nFlowline1DBound)

[nodobc-n2dobc]

Total number of flowlines (nFlowline)

[number of flow lines]

Number of Pumps (nPumps)

[jap1d]

Number of potential breaches (nBreaches)

[levnms]