GENESIS Version 3 -- Summary of model enhancements/updates
Milestones in the development of GENESIS
GENESIS version 2 was initially released in December 1989 and
represented the first public release of the GENESIS model. Technical
documentation of the GENESIS model was provided with this release of the
model in Technical Report CERC-89-19 (Report 1), Hanson and Kraus, 1989, and
is commonly known among GENESIS users as the "Technical Reference" manual.
In September 1991, GENESIS version 2.5 was released together with the GENESIS
system support programs. Technical documentation with step-by-step example
applications of each of the GENESIS system support programs was provided in
Technical Report CERC-89-19 (Report 2), Gravens, Kraus and Hanson, 1991, and
is commonly referred to as the "GENESIS Workbook." The GENESIS system support
programs were developed to automate many of the tasks associated with
conducting a design level numerical shoreline evolution investigation using the
GENESIS model. The motivation for the development of the system support
programs, was a recognition of the requirement to utilize computer programs to
develop the required input data streams necessary to run the GENESIS model, and
the need for standardization of analysis procedures and techniques which
access standardized data bases (e.g., Wave Information Study wave hindcast data
bases, Hubertz, et.al. 1993), or output from other numerical models (e.g.,
RCPWAVE), and generate intermediate analysis results or direct input data
streams for GENESIS. In August 1992, the GENESIS system support programs, the
numerical models GENESIS and RCPWAVE, together with model configuration data
editors and graphics programs for GENESIS and RCPWAVE, were released in an
integrated menu driven system known as the Shoreline Modeling System (SMS).
A user's manual for the SMS was provided in Instruction Report CERC-92-1,
"User's Guide to the Shoreline Modeling System" (Gravens 1992).
Development of the GENESIS model has continued based on identified
needs for model improvement brought to light through application of the model
to increasingly diverse coastal settings. The release and distribution of the
present version of the GENESIS model referred as version 3, includes several
model upgrades and enhancements that have been developed since the release of
GENESIS version 2.5. A summary overview of the model upgrades is given in the
following and formal documentation will be prepared, published, and
disseminated upon completion.
GENESIS Version 3 - Upgrades and Enhancements
The major upgrades and enhancements included in version 3 of the GENESIS
model can be categorized into four topic areas.
- New algorithms for wave diffraction and different procedures
for computing the cumulative effect of multiple wave energy
sources impacting a given shoreline reach.
- Addition of a moving shoreline position boundary condition.
- Addition of the capability to simulate mechanical sand
bypassing operations within the model domain.
- Incorporation of an improved representation of groins and
A summary of each of these model upgrades or enhanced capabilities are given in
Wave diffraction and the cumulative effect of multiple wave energy sources.
The concept of wave energy windows is central to GENESIS and determines
its algorithmic structure. Wave energy windows provide a powerful means of
describing breaking wave conditions alongshore and the associated sand
transport for a variety of configurations of coastal structures. For a
complete description of the concept of wave energy windows, sand transport
calculation domains, and multiple diffraction see pages 77-80 in the Technical
Reference. As originally formulated, breaking wave conditions alongshore were
individually computed for each wave energy window. The resulting shoreline
change was computed based on a summation of longshore sand transport rates
calculated from each of the energy windows. This calculation procedure was
found to result in unrealistic shoreline evolution in instances where multiple
wave energy windows influenced the same sand transport domain and some energy
windows were inside (landward) of the breaker line while other energy windows
were outside (seaward) of the breaker line. The enhancement discussed here has
changed this calculation procedure. The new procedure involves computing a
single energy-based breaking wave field along the entire model domain prior to
calculating sand transport rates and the resulting shoreline change. This
means that instead of summing sand transport rates for a reach of shoreline
influenced by multiple wave energy windows, an energy-based sum of the various
breaking wave fields (one for each wave energy window) is first computed and
then sand transport rates are computed only once and shoreline change is
subsequently calculated. This model enhancement, is confined entirely within
the computational portion of the model and requires no additional model input.
Moving shoreline position boundary condition.
As originally formulated the GENESIS model allowed for the specification
of two distinct lateral boundary conditions, the "pinned-beach" and the "gated"
boundary conditions. For a complete discussion of these boundary condition see
pages 41-42, 86-89, and 99-101, in the Technical Reference. In many
applications involving simulation of shoreline change it is possible to
identify portions of the beach that might serve as model domain boundaries
which are moving with a fairly constant rate. In those cases, the two
originally available boundary condition formulations in GENESIS are not
appropriate. The moving shoreline position boundary condition upgrade
addresses this model weakness by generalizing and expanding the originally
formulated "pinned beach" boundary condition. The pinned beach boundary
condition is equivalent to a moving boundary at which the movement is specified
as zero. Implementation of this model upgrade requires additional input data
not previously required. The new model inputs are specified in the START file
on lines C.4 through C.12. The START file distributed with the GENESIS
software reflects these additional input lines which are self-explanatory.
Mechanical sand bypassing.
This capability is analogous to including point or line sources or sinks
of sand within the model domain, but in practice this is most often associated
with mechanical sand bypassing operations and is consequently referred to as
such. The model upgrade allows the user to specify point or line sources or
sinks of sand anywhere within the model domain. Implementation of this model
upgrade within GENESIS again requires input data not previously required by
the model. As implemented specifying bypassing operations in a given GENESIS
simulation can be done in one of two ways, either entirely within the START
file, or through the use of an additional input data file called "BYPASS"
together with specific entries in the START file. Within the START file,
model inputs regarding specification of bypassing operations are contained
in section "J" which includes entries for ten specific data values or arrays.
The START file distributed with the GENESIS software reflects these additional
START file input lines and are self-explanatory. Also distributed with the
GENESIS software is an example BYPASS data file which can be used as a template
for generating additional BYPASS data files.
Improved representation of groins and jetties.
Groins and jetties have been represented in GENESIS throughout its
development, and shoreline change has been successfully simulated for cases
involving jetties and groins in the field and in physical models. However,
predicted shoreline response adjacent to groins has been regarded by the
GENESIS model developers as needing improvement, particularly for groins that
are both permeable and diffract waves. The groin boundary condition
enhancement included in GENESIS version 3 was revised based on the following
- Bypassing should be represented such that the shoreline response
to a groin, including evolution of the shoreline in time and its
equilibrium plan form, depend on groin length (actually, depth at
tip of groin since a specified profile shape is assumed), with an
increase in length increasing the impact of the structure on the
- Different groin permeabilities should produce different equilibrium
plan forms, with increasing permeability decreasing the impact of
the structure on the shoreline.
- A permeability of 100% should result in longshore sand transport
and shoreline evolution identical to that with no groin present.
This model enhancement is contained entirely within the computational portions
of the GENESIS model and requires no additional model inputs. In fact, a
previously required model input (START file line F.2) variable "SLOPE2",
representative bottom slope near groins, has been eliminated. Previous
versions of GENESIS used this input specification to compute the depth at
the tip of the groin which is required to calculate the magnitude of sand
bypassing seaward of the groin. In GENESIS version 3, an equilibrium profile
shape of the form y=Ax**(2/3) is used to calculate the depth at the tip of
the groin. The sediment scale parameter " A " is calculated using
user-specified grain size information input to the model.
Comments and Questions.
Each of the above described model enhancements and upgrades have been
implemented and tested by CERC personnel and others to the extent possible.
However, because the model allows, in effect, an infinite number of possible
coastal configurations it is possible that a unrealistic representation of
shoreline change could occur as a result of a specific model configuration.
If this should occur, or if you have questions regarding the model
formulation, or if you require clarification or additional information
regarding the GENESIS version 3 model enhancements and upgrades, please
contact Mark Gravens by phone at (601)634-3809, or fax at (601)634-4314, or
Email at firstname.lastname@example.org, or by mail:
USAE Waterways Experiment Station
Mark Gravens (CEWES-CR-P)
3909 Halls Ferry Rd
Vicksburg, MS 39108-6199