CEDAS Details

CEDAS – Coastal Engineering Design and Analysis System

General Engineering Module includes:


ACES (Automated Coastal Engineering System) is itself an integrated collection of coastal engineering design and analysis software. ACES provides a comprehensive environment for applying a broad spectrum of coastal engineering technologies. It uses the CEDAS window-oriented intuitive interface to access the underlying collection of coastal engineering design and analysis technologies, prepare various and often-large input data sets, and visualize results.

Functional areas covered by the ACES system include:

  • wave prediction
  • wave theory
  • wave transformation
  • structural design
  • wave runup, transmission, and overtopping
  • littoral processes
  • inlet processes
  • harbor design


Click here to see a listing of ACES models.



EST (Empirical Simulation Technique) is a life-cycle approach to risk analysis based on bootstrap resampling-with-replacement, interpolation, and smoothing of observed and/or computed information about site-specific historical events.

Disposal sites

Dune / beach recession

Storm surge stage and wave runup frequency

Storm event impacts in estuaries

The Empirical Simulation Technique (EST) is a bootstrap-based statistical procedure for simulating multiple time sequences of non-deterministic multi-parameter systems such as storm events and their corresponding environmental impacts. Results of the multiple repetitions are subsequently analyzed to compute frequency-of-occurrence relationships for storm effects such as coastal erosion and storm surge. Because multiple life-cycle scenarios are simulated through the EST, mean value frequencies are computed along with error estimates of deviation about the mean.

The EST utilizes observed and/or computed parameters associated with site-specific historical events as a basis for developing a methodology for generating multiple life cycle simulations of storm activity and the affects associated with each simulated event. Contrary to the Joint Probability Method, the technique does not rely on assumed parametric relationships, but uses the joint probability relationships inherent in the local database. Hence, probabilities are site specific, do not depend on fixed parametric relationships, and do not assume parameter independence. Therefore, theEST is “distribution free” and nonparametric.


RELIABLE is a code to compute a Level II analysis of the reliability (or failure probability) of a structure design. Key formulas for varying structure types, armor units, etc., are cast into a performance function equation with partial safety factors. Users need only provide the required statistics for the parameters of interest.

Reliability methods are readily adaptable to a wide variety of coastal structure design and evaluation problems and provide a powerful tool for rationally making economic compromises that are always necessary in civil engineering. The RELIABLE Code allows a Level II analysis, namely, it approximates Reliability assuming the Limit state equation is normally distributed and converts all random correlated non-normally distributed variables to non-correlated normally distributed variables, or assuming a mathematically simplified form of the failure surface, or both. RELIABLE employs a Taylor Series expansion of the Limit state equation about some critical point and Reliability is computed as the minimum distance between the failure surface and zero. A discussion of this approach can be found in Melby and Mlakar (1997).Any limit state equations or performance functions can be used in the reliability analysis. TheCoastal Engineering Manual (see CEM 2.01 Professional Edition) lists a considerable number of equations dealing with most aspects of coastal structure design. In addition, the CEM has a chapter devoted to Reliability Analysis where several limit state equations and associated statistics are given. Rather than developing codes specific to a given set of equations, RELIABLE takes the approach of solving two general expressions that together can represent most any equation in the CEM pertinent to structure analysis.

Inlet Processes Module


NMLONG-CW (Numerical Model for simulating LONGshore current – Current-Wave interaction) calculates wave height and angle, mean water surface, longshore current, wave-current interaction, and sediment transport rate for beaches with arbitrary bottom contours that are uniform alongshore. The mean current and water-level change induced by obliquely incident waves, wind, and externally-imposed tidal current are simulated.
Recent enhancements to NMLONG-CWprovide calculations of cross-shore distribution of the longshore sediment transport rate on a barred profile under either monochromatic or random waves. A more accurate wave blocking routine is used in the face of strong currents. Finally, a wave roller model is included to permit simulation of momentum flux introduced by wave breaking before energy dissipation actually occurs.The major assumptions in NMLONG-CW are longshore homogeneity (straight and parallel bottom contours) and linear wave theory. Potential applications of NMLONG-CWinclude estimating the distribution and magnitude of sediment or pollutant transport, estimating wave overtopping and wave forces, and preliminary structure design, such as length and placement of groins and breakwaters.

DYNLET (DYNamic behavior of tidal flow at inLETs) is a powerful 1-D hydrodynamic model for riverine, estuarine, or coastal problems.  DYNLET predicts tide-dominated velocities and water level fluctuations at an inlet and interior back bay system. It can also serve as a generalized model for one-dimensional channel flow in river or estuarine systems. The model solves the full one-dimensional shallow water equations employing an implicit finite difference technique. It provides detailed velocity information across channels and is able to describe multi-channel inlets or river systems. The model can be used for design-level studies simulating 1-D fluid flow from the ocean through a tidal inlet, into back-bay regions, and up tributaries.

Key Features in DYNLET include:

  • Variable bottom elevations and friction coefficients at user-specified stations across channel cross sections.
  • Use of channel conveyance for describing friction loss.
  • Computation of the velocity field at stations that can be spaced arbitrarily across each cross section (at each node).
  • Optimization of the computational procedure by employing a banded matrix solver for channel networks.
  • Generalization of external and internal boundary conditions so that channel networks and multiple entrances can be described.
  • Capability to include culvert influence in the network.
  • Automated grid generation.

Beach Processes Module includes:


NEMOS (Nearshore Evolution MOdeling System) is a set of codes that operates as a system to simulate the long-term planform evolution of the beach in response to imposed wave conditions, coastal structures, and other engineering activity (e.g., beach nourishment).

The system consists of the following key codes:

  • GENESIS (GENEralized Model for SImulating Shoreline Change) is a
    model for calculating shoreline change caused primarily by wave action and can be applied to a diverse variety of situations involving almost arbitrary numbers, locations, and combinations of groins, jetties, detached breakwaters, seawalls, and beach fills. The system is based on one-line theory, whereby it is assumed the beach profile remains unchanged permitting beach change to be described uniquely in terms of the shoreline position. The program can be applied to a diverse variety of situations involving almost arbitrary numbers, locations, and combinations of groins, jetties, detached breakwaters, seawalls, and beach fills. Other features included in the system are wave shoaling, refraction, and diffraction; sand passing through and around groins, and sources and sinks of sand.The GENESIS package is structured to enable complete design-level shoreline evolution investigations to be performed by engineers regardless of their computer-programming capabilities.GENESIS now contains two solution schemes – implicit (for general use) and explicit (to simulate tombolo formation). The explicit scheme is referred to as GENESIS-T. New features also include capability to use tidal currents, variable transmission through detached breakwaters, and a regional contour trend to help model crenulated beaches more accurately.


  • RCPWAVE (Regional Coastal Processes WAVE propagation model) is a 2-D, steady state, monochromatic short wave model for simulating wave propagation over arbitrary bathymetry. The governing equations solved in the model are the “mild slope” equation for linear, monochromatic waves, and the equation specifying irrotationality of the wave phase function gradient. Finite-difference approximations of these equations are solved to predict wave propagation outside the surf zone. These equations account for shoaling, refraction and bottom-induced diffraction within a study area. Included in the model is an algorithm for treating wave breaking. Results include wave height, wave angle, and wave number at each grid location.
  • STWAVE (STeady WAVE) is a 2-D finite-difference representation of a simplified form of the spectral balance equation to simulate near-coast, time-independent spectral wave energy propagation.

The model assumes:

  • only wave energy directed into the computational grid is significant, i.e., wave energy not directed into the grid is neglected, and
  • wave conditions vary slowly enough that the variation of waves at a given point over time may be neglected relative to the time required
    for waves to pass across the computational grid.


is based on a simplified form of the spectral balance equation. The model now has capability of using tidal currents, nested grids, and a variable ocean boundary condition.

The wave models and GENESIS can be used independently. There are also several auxiliary codes in NEMOS allowing for constructing grids, developing input data sets, and visualizing results.


These auxiliary codes include:

SPECGEN is a helper application used to import, create, or visualize directional spectra for use inSTWAVE. It can be run as a standalone application, or invoked from within CEDAS when working on data for STWAVE.

GRIDGEN is a code to create uniform grids at arbitrary orientations from random bathymetry/topography data. This code now permits construction of both the wave model and GENESISgrids.

WSAV (Wave Station Analysis and Visualization) is used to perform statistical analysis of series of wave events, graphically displaying the results of these analyses, and producing a representative group of wave events for use in simulations.


WMV(WaveModelVisualization) is an application for performing graphical analysis from the various uniform rectilinear grid models within CEDAS. It displays data produced by wave model simulations solved on uniform rectilinear grids. The various plan views of scalar and vector data is overlaid for simultaneous viewing. In 3-D views, several planes of plan views can be stacked above one 3-D surface.

WWWL (Waves, Winds, Water Levels) Editor is used for specifying and editing a variety of record-oriented data types. Common data sources include WWWL databases, analyzed gage data, statistically-derived datasets, theoretical cases, and data derived from other model simulations.

WISPH3 (WISPHase 3 Wave Transformation) is a simplified point-to-point steady-state spectral transformation of WIS 2-component wave descriptions from deeper water to an arbitrary shallower water depth. From basic parametric wave descriptions (H, T, theta) for each of 2 components, it generates theoretical directional spectra, performs shoaling and refraction, and considers shore-induced sheltering at a nearshore location.



  • SBEACH (Storm-induced BEAch CHange) simulates cross-shore beach, berm, and dune erosion produced by storm waves and water levels. The latest version allows simulation of dune erosion in the presence of hard bottom and has improved graphics and file standards. The model is applied in beach fill project design and evaluation and in other studies of beach profile change.SBEACH operates in the CEDAS graphical user interface designed to facilitate data input, model setup and execution, and analysis of model results.


  • BMAP (Beach Morphology Analysis Package) is a collection of automated and interactive tools to analyze morphologic and dynamic properties of beach profiles. BMAP is dynamically linked withSBEACH to support beach erosion analysis, but can be operated as a stand-alone program for general analysis of beach profile shape and beach profile change. The program operates in the CEDASgraphical user interface that enables rapid and intuitive analysis and manipulation of large amounts of beach profile data.


BMAP tools include:


ACES Models

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