Mathematical Model SEDIMORPH

Short Description

The mathematical model SediMorph is a morphodynamic model which simulates the physical processes in the soil under surface waters. To do this the mass movements of the different grain classes according to bed load and suspended load transport and the pore water are balanced, respectively.

SediMorph is able to work on unstructured orthogonal grids (UOG). The modelling domain is covered by a grid consisting of a set of non-overlapping convex polygons, usually either triangles or quadrilaterals. The grid is said to be an unstructured orthogonal grid if within each polygon a point (hereafter called a center) can be identified in such a way that the segment joining the center of two adjacent polygons and the side shared by the two polygons, have a non-empty intersection and are orthogonal to each other. The vertical co-ordinate is resolved by horizontal layers with having unequal depths.

Physical processes

SediMorph can include the following processes:

• variation of the grain size distribution in space and time,
• spatial variation of bed forms,
• prediction of ripples and dunes and the pore water content,
• spatial variation of the bottom roughness resulting from grain and form roughness;
• variation of the bed shear stress in space and time, resulting from variations of the bed roughness and the overlying currents,
• bed shear stresses resulting from waves,
• erodibility of the bed sediments as a function of the pore water content,
• calculation of the erosion rates,
• calculation of the bed load transport rates for each fraction,
• combination of bed load and suspended load for (fine) sands,
• simulation of the morphodynamics (Change of the water depths in space and time) as a result of bed load and suspended load transport,
• accelerated bed evolution through scaling of the transport rates.

Simulation results

Synoptic results in BDF- and/or UGRID CF-NetCDF file types for:

• the distribution of the sediment fractions
  1. in percent, or
  2. as available mass in kg/m².
• the mean grain diameter
• the grain roughness
• the pore water content
• the dune heights and lengths
• the ripple heights and lengths
• the transport capacities of every sediment fraction
• the transport rates of every sediment fraction
• the erosion rates of every sediment fraction
• the deposition rates of every sediment fraction
• the integrated mass fluxes

Publications

1. Malcherek, A. and Putzar, B. (2003). The Prediction of Dunes and Their Related Roughness in Estuarine Morphological Models. 8th Int. Conference on Estuarine and Coastal Modeling, Monterey, CA.
2. Malcherek, A. and Piechotta, F. (2004). Investigations on the Porosity as a Parameter for Sediment Erodibility. 9th Int. Symp. River Sedimentation, Vol. III, pp. 1913-1918.
3. Knoch, D. and Malcherek, A. (2005). The influence of waves on the sediment composition in a tidal bay. 9th Int. Conference on Estuarine and Coastal Modeling, Charlston.

Standard Validation document

A. Malcherek, F. Piechotta, D. Knoch Mathematical Module SediMorph - Standard Validation Document Version 1.1, Technical Report, Bundesanstalt fuer Wasserbau, 2005.

A PDF-version is freely available for download:

• (ca. 2.5 MB) SEDIMORPH Validation document

User Group (in alphabetical order)

• Anchor QEA, LLC, San Francisco, CA 94111, USA
• Bundesanstalt fuer Wasserbau;
• Professur fuer Hydromechanik und Wasserbau am Institut fuer Wasserwesen, Universitaet der Bundeswehr, Muenchen.

BAW-specific informations

Simulation

The SEDIMORPH model can be used via direct coupling with the three-dimensional mathematical model UNTRIM or the two-dimensional mathematical model TELEMAC-2D for hydrodynamics and transport processes. Further information about the steering of the model can be found on the page of the steering file sedimorph.dat.

Graphical representation of simulation results

There are different methods available for the graphic representation of the results produced by SEDIMORPH:

• HVIEW2D, for files of type BDF,
• Davit (A product of SmileConsult), for files of type BDF as well as for files of type UGRID CF-NetCDF,
• NCPLOT, for files of type UGRID CF-NetCDF-Format

Analysis of Computational Results

A great variety of methods for analyses of computational results is available which enables the user to respond to many different questions.

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Overview