# IPDS.DAT

### From BAWiki

## Basic Information

### File-Type

ipds.dat

### File-Form

FORMATTED

### Version

1.4

### Description-Date

February 2021

## Significance of the File

A file of type ipds.dat contains ** i**nitial values of

**hysical**

__p__**ata**

__d__**ets The possibilities using this file (e.g. to define start conditions) may illustrate these examples. All improvements coming with Version 1.4 are marked as follows: New in V1.4**

__s__## File-Contents (in Catchwords)

- Block date_and_time
- date and time specification
- exactly one specification allowed
- the following formats are implemented:

- DD.MM.YYYY-hh:mm:ss
- DD.MM.YYYY-hh:mm:ss.nnnnnnnnn
- DD.MM.YYYY-hh:mm:ss.nnnnnnnnn-ZONE

- legend:

- DD = day of month (two digits 01-31)
- MM = month of year (two digits 01-12)
- YYYY = year (four digits)
- hh = hour of day (two digits 00-23)
- mm = minute of hour (two digits 00-59)
- ss = second of minute (two digits 00-59)
- nnnnnnnnn = nanoseconds (nine digits)
- ZONE = time zone (UTC/MEZ/MESZ/+3H/..)

- key line:
**datetime = DD.MM.YYYY-hh:mm:ss.nnnnnnnnn-ZONE**

- Block
**global_constant_values**- definition of physical constant values in the whole area (default values)
- exactly one
**global_constant_values**block allowed - these default values can be overwritten by regional valid values via the regional_values) blocks
- implemented physical values:

- water level

- key line:
**waterlevel = ..value..** - exactly one specification allowed

- key line:

- salinity

- key line:
**salinity = ..value..** - exactly one specification allowed

- key line:

- temperature

- key line:
**temperature = ..value..** - exactly one specification allowed

- key line:

- sediment fractions and porosity

- key line for one sediment fraction:
**sediment_fraction = ..sediment_name.. ..fraction..** - use as many sediment fraction key lines as necessary
- key line for porosity:
**porosity = ..fraction..** - exactly one specification allowed for porosity
- all used sediment names must be identical to the names defined in the sediment classification file (type soil.dat)
- the sum of all sediment fractions must be 1

- key line for one sediment fraction:

- ripple wave number

- the wave number k defines both direction and wavelength (λ) of a ripple structure (k = 2 π / λ)
- defining the wave number by giving its x- und y-component values
- key line:
**ripple_wavenumber = ..x-component.. ..y-component..** - exactly one specification allowed

- ripple height

- key line:
**ripple_height = ..value..** - exactly one specification allowed

- key line:

- dune wave number

- the wave number k defines both direction and wavelength (λ) of a dune structure (k = 2 π / λ)
- defining the wave number by giving its x- und y-component values
- key line:
**dune_wavenumber = ..x-component.. ..y-component..** - exactly one specification allowed

- dune height

- key line:
**dune_height = ..value..** - exactly one specification allowed

- key line:

- depth of the unerodable layer

- implemented are two ways ("absolute" and "relative") of giving the depth of the unerodable layer
- absolute depth is necessary if the unerodable layer lies in a geodetic (absolute) depth
- relative depth means the unerodable layer lies in a depth relative to the bottom of the water body (negative values represents values below the bottom of the water body)
- key line:
**rigid_layer_depth = relative|absolute ..value..** - exactly one specification allowed

- roughness of the unerodable layer

- the roughness of the unerodable layer is important if there are no sediments left at the bottom of the water body
- two specifications are necessary to define the roughness of the unerodable layer

- specification of the used bed shear stress formula (at this time only the effective bed roughness according to nikuradse is implemented)
- specification of the roughness coefficient

- key line:
**rigid_layer_roughness = nikuradse ..value..**

- control volume number

- key line:
**control_volume_number = ..value..**

- key line:

- additional roughness

- key line:
**additional_roughness = nikuradse ..value..** - the roughness value must be greater or equal -1 and less than 1

- key line:

- concentration of suspended load

- key line:
**suspendedload = ..sediment_name.. ..value..** - use as many concentration of suspended load key lines as necessary

- key line:

- z0 roughness length

- key line:
**z0_roughnesslength = ..value..** - the roughness value must be greater or equal 0 and less than 10

- key line:

- chezy bottom friction coefficient

- key line:
**bottom_friction_chezy = ..chezy-value..** - the roughness value must be greater or equal 0 and less than 1000

- key line:

- manning bottom friction coefficient

- key line:
**bottom_friction_manning_str = ..manning-value..** - the roughness value must be greater or equal 0 and less than 1000

- key line:

- nikuradse bottom friction coefficient

- key line:
**bottom_friction_nikuradse = ..nikuradse-value..** - the roughness value must be greater or equal 0 and less than 1

- key line:

- white colebrook bottom friction coefficient

- key line:
**bottom_friction_white_colebr = ..white-colebrook-value..** - the roughness value must be greater or equal 0 and less than 1

- key line:

- taylor bottom friction coefficient

- key line:
**bottom_friction_taylor = ..taylor-value..** - the roughness value must be greater or equal 0 and less than 0.1

- key line:

- time dependent bathymetry

- key line:
**time_dependent_bathymetry = ..value..** - the bathymetry value must be greater or equal -99 and less than +99

- key line:

- critical stress for deposition

- key line:
**critical_stress_for_deposition = ..value..** - the critical stress value must be greater or equal 0 and less than 99

- key line:

- critical stress for erosion

- key line:
**critical_stress_for_erosion = ..value..** - the critical stress value must be greater or equal 0 and less than 99

- key line:

- erodibility parameter

- key line:
**erodibility_parameter = ..value..** - the erodibility value must be greater or equal 0 and less than 100

- key line:

- sediment mass

- key line:
**sediment_mass = ..value..** - the sediment mass value must be greater or equal 0 and less than 1 Million

- key line:

- current velocity in x direction

- key line:
**current_velocity_(x-dir.) = ..value..** - the velocity value must be greater or equal -10 and less or equal +10

- key line:

- current velocity in y direction

- key line:
**current_velocity_(y-dir.) = ..value..** - the velocity value must be greater or equal -10 and less or equal +10

- key line:

- deposition rate

- key line:
**deposition_rate = ..sediment_name.. ..value..** - use as many deposition rate key lines as necessary

- key line:

- mean wave period

- key line:
**mean_wave_period = ..value..** - the wave period value must be greater than 0 and less or equal 100

- key line:

- significant wave height

- key line:
**significant_wave_height = ..value..** - the wave height value must be greater or equal 0 and less or equal 15

- key line:

- mean wave direction x component

- key line:
**mean_wave_direction_(x-dir.) = ..value..** - the direction value must be greater or equal -10 and less or equal +10

- key line:

- mean wave direction y component

- key line:
**mean_wave_direction_(y-dir.) = ..value..** - the direction value must be greater or equal -10 and less or equal +10

- key line:

- artificial porosity

- key line:
**artificial_porosity = ..value..** - the porosity value must be greater or equal 0 and less or equal 1

- key line:

- hydrodynamic pressure

- key line:
**hydrodynamic_pressure = ..value..** - the pressure value must be greater or equal -0.1 and less or equal +0.1

- key line:

- tracer fraction

- key line:
**tracer_fraction = ..tracer_name.. ..value..** - use as many tracer key lines as necessary

- key line:

- turbulent kinetic energy

- key line:
**turbulent_kinetic_energy = ..value..** - the energy value must be greater or equal 0 and less or equal 10

- key line:

- generic length scale

- key line:
**generic_length_scale = ..value..** - the length scale value must be greater or equal 0 and less or equal 10

- key line:

- Block
**region**- definition of regions
- the maximum number of regions is unlimited
- at least one region is necessary to define regional differing physical values
- it is allowed to use no regions
- each region needs a name:

- this name will be used as an identification key
- notice case sensitivity
- key line:
**region_name = ..name..**

- description of the border polygon

- the border polygon need at least three border points
- the maximum number of border points is unlimited
- the border polygon will be closed automatically
- key line for one border point:
**border_point = ..x-coordinate.. ..y-coordinate..**

- Block
**sampling_point**- definition of positions related to measured data
- the maximum number of positions is unlimited
- at least one position is necessary to define regional differing physical values
- it is allowed to use no positions
- each position needs a name:

- this name will be used as an identification key
- notice case sensitivity
- key line:
**sampling_point_name = ..name..**

- position specification

- specification of x- and y-coordinate
- only one position specification is allowed
- key line:
**sampling_point_xy = ..x-coordinate.. ..y-coordinate..**

- definition of physical values valid at the position

- it is allowed to use the same physical values as described in the global_constant_values block

- Block
**regional_values**- definition of regional differing physical values
- specification of regions with physical values related to positions
- in the space between the positions the physical values will be interpolated
- the maximum number of these blocks is unlimited
- it is allowed to use no
**regional_values**block (the physical constant values for the whole area will not change) - sorting the regional_values blocks so that the block with the lowest priority will come first (this is important only if the regions overlap)
- specification of the region

- key line:
**region = inside|outside ..name..** - the name of the region must match with the region identification key defined in one of the region blocks
- with the "inside" or "outside" key word it is possible to define the region of interest inside or outside the region border polygon

- key line:

- specification of the geodetic layer

- key lines:
**lower_validity_level = ..lower_limit..****upper_validity_level = ..upper_limit..** - both specifications are not necessary

- key lines:

- specification of positions

- the maximum number of positions is only limited to the maximum number of defined sampling_point blocks
- at least one position is necessary
- in the presence of only one position the physical values are constant over the whole region of interest
- the names of all positions must match with the position identification keys defined in the sampling_point blocks
- key line:
**sampling_point = ..name..**

- specification of a maximum distance between positions and a given point P. Only positions inside a distance radius around P are used for interpolation.

- only one specification allowed
- the value for maximum distance must be greater zero
- key line:
**sampling_point_maxdist = ..maximum_distance_to_positions..** - the key line ist not necessary. if maximum distance ist not specified, the default value (
**40.E6**) will be used. so it is ensured that older IPDS files (version 1.1) will produce the same result as before. - The following pictures will document the influence of the maximum distance: Visualized in all pictures is the computed distribution of fine sand (.063-.177 mm grain diameter) for the mouth of the ems river. the computation started with 1382 measurement positions from the Rijksinstituut voor Kust en Zee (RIKZ) sediment atlas. The colours represents different rates of fine sand: red represents 100%, yellow 75%, green 50% and dark blue 0% rate of fine sand.

- The maximum distance to the positions (300m) corresponds to the internal grid resolution

The interpolation takes place only around positions. For all other grid points the measurement positions all too far away. The locations of the positions come clearly to sight. (642x768 Pixel, 21kB). - The maximum distance to the positions (1000m) is about 3-4 times greater than the internal grid resolution

The interpolation takes place in all areas where positions are not too far away The result as a first approximation is nature alike. In wide areas will be no interpolation, because of the great distance to positions. (642x768 Pixel, 30kB). - No specification of a maximum distance The interpolation takes place everywhere for all grid points. Far away of the positions the result will be artificial. (642x768 Pixel, 85kB).

- The maximum distance to the positions (300m) corresponds to the internal grid resolution

- specification of the interpolation method
- key line:
**interpolation_method = nearest_points_in_sectors | linear_distance_weighting | triangular_interpolation** - The interpolation method
**nearest_points_in_sectors**is developed at BAW and and tries to look for the nearest positions in different directions (sectors) for a point of interest. The physical values at all positions found will be averaged dependant to the square of the distance to the positions (1/d**2). - New in V1.4 The method
**linear_distance_weighting**works as described for**nearest_points_in_sectors**with one difference: The physical values will be averaged dependant to the distance to the positions (1/d). - At first the interpolation method
**triangular_interpolation**creates a grid of all available positions. This grid follows Delaunay-criteria and covers a convex hull around all positions. The grid generation process takes place in an external software package so called GEOMPACK (author: Barry Joe) and gives back the grid via the interface**ext_ipds_setup_mespos_tria**.

## Programs using this Type of File

GEOTRANSFORMER, NCAGGREGATE, NCCUTOUT, TELEMAC-2D [SediMorph], UNS, UNTRIM [SediMorph], UNTRIM2, UNTRIM2007 [SediMorph]

### Example-File

$PROGHOME/examples/ipds/ipds.dat

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