IPDS.DAT

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 initial values of physical datasets 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

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
- salinity
key line: salinity = ..value..

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

exactly one specification allowed
- 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
- 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
- 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
- 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..
- additional roughness
key line: additional_roughness = nikuradse ..value..

the roughness value must be greater or equal -1 and less than 1
- concentration of suspended load
key line: suspendedload = ..sediment_name.. ..value..

use as many concentration of suspended load key lines as necessary
- z0 roughness length
key line: z0_roughnesslength = ..value..

the roughness value must be greater or equal 0 and less than 10
- chezy bottom friction coefficient
key line: bottom_friction_chezy = ..chezy-value..

the roughness value must be greater or equal 0 and less than 1000
- 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
- nikuradse bottom friction coefficient
key line: bottom_friction_nikuradse = ..nikuradse-value..

the roughness value must be greater or equal 0 and less than 1
- 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
- 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
- time dependent bathymetry
key line: time_dependent_bathymetry = ..value..

the bathymetry value must be greater or equal -99 and less than +99
- 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
- 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
- erodibility parameter
key line: erodibility_parameter = ..value..

the erodibility value must be greater or equal 0 and less than 100
- sediment mass
key line: sediment_mass = ..value..

the sediment mass value must be greater or equal 0 and less than 1 Million
- 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
- 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
- deposition rate
key line: deposition_rate = ..sediment_name.. ..value..

use as many deposition rate key lines as necessary
- mean wave period
key line: mean_wave_period = ..value..

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

the wave height value must be greater or equal 0 and less or equal 15
- 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
- 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
- artificial porosity
key line: artificial_porosity = ..value..

the porosity value must be greater or equal 0 and less or equal 1
- hydrodynamic pressure
key line: hydrodynamic_pressure = ..value..

the pressure value must be greater or equal -0.1 and less or equal +0.1
- tracer fraction
key line: tracer_fraction = ..tracer_name.. ..value..

use as many tracer key lines as necessary
- turbulent kinetic energy
key line: turbulent_kinetic_energy = ..value..

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

the length scale value must be greater or equal 0 and less or equal 10
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
- specification of the geodetic layer
- key lines: lower_validity_level = ..lower_limit..
  upper_validity_level = ..upper_limit..
- both specifications are not necessary
- 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).

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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