The final information in the model-parameter file is specification of the
special output points. These points are I, J (x grid cell index, y grid cell index)
pairings of these special output points. There must be NSELCT pairs of
numbers. The values are again read in free format and may occupy as many lines
as needed (one pair per line).
The default name of the model parameter file is options.std. In SMS,
the file is specified with a project name and the "std" extension, project.std. A
sample model parameter file is given in Appendix A. The sample file specifies
that the model run will consider propagation and source terms (IPRP = 0), wave-
current interaction is included (ICUR = 1), breaker indices are written to a file
(IBREAK=1), and radiation stress gradients are written to a file (IRS=1). Three
output points have been selected (at I, J coordinates (110,157), (131,117), and
(146,86)).
Bathymetry
The bathymetry file gives the STWAVE grid size and grid spacing and
defines the grid bathymetry. The first line of the file, read using free format,
includes (in the following order):
NI = Number of cross-shore (x) grid cells or columns. The value of NI,
together with the grid spacing (DXINC), determines the cross-shore extent of the
modeling domain and the location of the offshore grid boundary. The offshore
boundary is typically placed in a region where the bathymetry contours are
relatively straight and parallel and where incident wave information is available
from a gauge or hindcast.
NJ = Number of alongshore (y) grid cells or rows. The value of NJ, together
with the grid spacing, determines the alongshore extent of the modeling domain
and the location of the lateral grid boundaries. The lateral extent of the grid is a
balance between keeping the lateral boundaries as far away as possible from the
region of engineering interest and keeping the grid domain small for
computational efficiency. The grid should extend sufficiently far alongshore to
include the bathymetric features that influence the engineering project (e.g., if a
project is centered on a coastal entrance, the entire ebb shoal and any offshore
features that influence refraction should be included in the model domain).
DXINC = Grid spacing in meters, which is the same in the x and y directions.
The grid spacing determines how finely bathymetric features and current fields
are resolved in the model and the spatial resolution of the output fields of wave
height, period, and direction. Grid spacing should be sufficient to define
bathymetric features and gradients (shoals, canyons, and channels) that are
important to the engineering project. Typical resolutions are tens to hundreds of
meters. For a fixed grid domain, increasing the grid resolution increases
computational time.
The remainder of the file gives the water depth (relative to some datum, such
as mean sea level or mean lower low water) for each grid cell in an STWAVE
16
Chapter 3 Input File Description
Previous Page
