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{{DISPLAYTITLE:Coastal Modeling System: Dredging Module}}
<p style="margin:0; background:#2580a2; font-size:20px; font-weight:bold; border:1px solid #a3bfb1; text-align:left; color:#FFF; padding:0.2em 0.4em;">CIRP-WN-12-1</p>
<p style="margin:0; background:#2580a2; font-size:20px; font-weight:bold; border:1px solid #a3bfb1; text-align:left; color:#FFF; padding:0.2em 0.4em;">CIRP-WN-17-1</p>


= Inlet Reservoir Model: Part II: PC-Interface =
<div style="text-align:left">'''''by Chris Reed and Alejandro Sanchez'''''</div><br>
<div style="text-align:left">'''''by Julie Dean Rosati, Mohamed Dabees, Wayne Tanner'''''</div><br>


__TOC__
__TOC__


==PURPOSE==
==PURPOSE==
This Wiki-Coastal and Hydraulics Engineering Technical Note (Wiki-CHETN) is the second in the Inlet Reservoir CHETN series. This CHETN describes the Inlet Reservoir Model (IRM) interface and setting up an IRM project. Part III of the IRM series presents guidance for application and two example problems. The IRM calculates the time-dependent volumetric evolution of inlet morphologic features such as ebb and flood shoals, and estimates bypassing to adjacent beaches based on user-specified relationships (Kraus 2000, 2002).
This Coastal and Hydraulics Engineering Technical Note (CHETN) describes the implementation of a dredging module (DM) within the U.S. Army Corps of Engineers (USACE) Coastal Modeling System (CMS). The DM simulates one or more dredging operations during a CMS simulation and provides options for the dredging and placement of material. The DM may be used in studies such as estimating future dredging requirements, evaluating alternative dredging
operations, and analyzing morphologic consequences of dredging operations. A coastal application at St. Marys Entrance Channel, FL, is provided to illustrate the setup procedure and demonstrate the model capability.  


==CITATION==
==CITATION==
  Rosati, J.D., Dabees, M., and Tanner, W. 2011. Inlet Reservoir Model, Part II: PC-Interface. Coastal and <br> Hydraulics Engineering Technical Note ERDC/CHL CIRP-WN-12-1. Vicksburg, MS: U.S. Army Engineer Research <br> and Development Center. A pdf version of this document is available on the [http://cirp.usace.army.mil/products/?tab=5#products CIRP Website].
<blockquote>Reed, C. and Sanchez, A. 2016. Coastal Modeling System: Dredging Module. Coastal and Hydraulics Engineering Technical Note ERDC/CHL CIRP-WN-17-1. Vicksburg, MS: U.S. Army Engineer Research and Development Center. </blockquote>
 
A pdf version of this document is available at the [http://www.dtic.mil/get-tr-doc/pdf?AD=AD1011630 Defense Technical Information Center].


==INTRODUCTION==
==INTRODUCTION==
The Inlet Reservoir Model (IRM) calculates time-dependent sediment bypassing around an inlet and associated volume change for inlet morphologic features as identified by the user, as a function of longshore sediment transport along the adjacent beaches, user-defined equilibrium volumes for each morphologic feature, and engineering activities in vicinity of the inlet. In a typical wave-dominated inlet, there would be three distinct ocean-side morphologic features: an ebb shoal, bypassing bar, and an attachment bar.  The concept of the Inlet Reservoir Model is based on the assumption that each feature has a maximum (equilibrium) sand-retention capacity that cannot be exceeded.  Once a feature has reached capacity, all additional sediment transport to that feature will bypass to the next feature(s), until sediment arrives at the downdrift side of the inlet, or is deposited in another location such as the inlet channel or flood shoal.  If a morphologic feature is partially full, it still provides partial bypassing.  The Inlet Reservoir Model calculates growth of the shoals as a function of the littoral drift and equilibrium volumes of the shoals, and it accounts for the naturally long timescales of large morphologic features and time delays in exchange of material among the features.
The CMS, developed by the Coastal Inlets Research Program (CIRP), is an integrated suite of numerical models for simulating water surface elevation, current, waves, sediment transport, and morphology change in coastal and inlet applications. It consists of a hydrodynamic and sediment transport model, CMS-Flow, and a spectral wave model, CMS-Wave (Buttolph et al. 2006; Sánchez et al. 2011a, b; and Lin et al. 2008). The CMS is interfaced
 
through the Surface-water Modeling System (SMS).
Formulation of the IRM was discussed in Part I of the series, CHETN-IV-39 (Kraus 2002), for one-direction of net longshore transport from the up-drift beach through the ebb-tidal shoal, bypassing bar, attachment bar, to the downdrift beach. Capabilities of the IRM have expanded since the initial formulation to include transport in both directions, potential contributions of various engineering activities in proximity or certain distance of the inlet (such as dredging of channels, deposition basins, and mining of shoals); and the IRM can include as many morphologic features as the user defines.  Previous studies that have used the IRM include Dabees and Kraus (2004, 2005, 2008); and Zarillo and Kraus (2003).
 
Figure 1 shows a schematic of an inlet system within the IRM with various types of reservoirs (e.g., channel, deposition basin) and morphologic features (e.g., ebb, flood shoal; bypassing bars).  Identification of these features and the associated pathways can be estimated based on:
 
* Shoreline position, bathymetric and topographic data to indicate shoals, impoundment areas and attachment bars;
* Aerial photographs delineating wave breaking patterns, the typical extent and coverage of the ebb tidal jet, and sediment transport pathways as indicated by sand leaking through or around structures, and visible morphology such as subaqueous bars, etc.;   
* Knowledge of engineering activities within the inlet system (e.g., dredging of a deposition basin or dredged channel);
* Knowledge of structural condition and layout (e.g., presence of a weir or degraded jetty, and segmentation or curvature of structure); and,
* Previous studies documenting sediment budgets, magnitudes and directions of longshore sand transport rates, and approximate sand transport pathways.
 
[[File:IRMPartIIFigure1.png|thumb|right|Figure 1. Schematic illustrating various reservoirs and morphologic features available in the IRM.]]
 
Within the IRM, the Ebb shoal “proper,” $E$, is defined as that portion of the ebb shoal that is directly within the ebb tidal jet, as indicated by a dashed line in Figure 1. The Bypassing bars, $B(1)$ and $B(2)$ are the portions of the ebb tidal shoal that are primarily influenced by wave-induced transport, and the Attachment bar, $A$, is the shore-attached feature that accretes in response to the wave reduction and delivery of sand provided by the Bypassing bar. It is important to realize that estimates of ebb shoal volumes documented in literature pertaining to a particular site most likely include the ebb shoal proper and bypassing bar. The IRM must delineate each morphologic feature to properly distinguish the temporal variation in growth and associated variation in bypassing.  Part III of the IRM series discusses methods to estimate the relative volumes of these features, as well as the equilibrium volumes.
 
As shown in Figure 1, sand transport pathways extend from the source (either transport towards the right (South Beach), $Q_{R in}$ or transport towards the left (North Beach), $Q_{L in}$ ) to associated features for which the user either defines or the IRM computes so-called “Coupling Coefficients.”  Coupling Coefficients define the proportion of the incoming sand volume that will be transported to the destination feature. For example, in Figure 1, the user may define for a long-term average that 30% of $Q_{L in}$ is transported to the Impoundment feature adjacent to the north jetty, $I$, and the remaining 70% is transported to the North Bypassing Bar, $B(1)$. The Coupling Coefficient to $I$ would be 0.3, and the IRM would compute the Coupling Coefficient to $B(1)$ as 0.7.  For other features with only one pathway, for example from $I$ to the Channel, $C$, the IRM calculates the Coupling Coefficient equal to 1.0. Other features in Figure 1 include a Shore accretion zone, $S$, which is fed by the Attachment bar, $A$; Deposition basin, $D$, inside the weir portion of the south jetty, which receives sand from the Shore, $S$; Flood shoal, $F$; and zones which only receive and are final “sinks” for sand, the Bay, $Y$, and Offshore, $O$.
 
Once morphologic features, pathways, coupling coefficients, equilibrium volumes for each reservoir (discussed in a following section), and engineering activities such as dredging of the Channel, $C$, or Deposition basin, $D$, are defined, the IRM solves the governing  equations that relate each feature's volume relative to its equilibrium volume and sand transport pathways into and out of each feature through time.  
 
''*Note: The IRM also allows the user to use different conventions for $Q_R$ and $Q_L$. The user may prefer to define $Q_R$ as “transport from the right beach,” and similarly for $Q_L$, “transport from the left beach.”''
 
==REVIEW OF THEORY==
A brief review of the IRM concept and development is discussed to provide the reader basics of the underlying IRM assumptions. For more detail, the reader is referred to Kraus (2000, 2002).  The underlying principles of the IRM are as follows (Kraus, 2000):
 
# Mass (sand volume) is conserved.
# Morphologic forms (reservoirs) and the sediment pathways among them can be identified, and the morphologic forms evolve while preserving identity.
# Stable equilibrium of the individual aggregate morphologic forms exists.
# Changes in meso- and macro-morphologic forms are reasonably smooth (e.g., these do not evolve abruptly).
 
The IRM is conceptualized as a series of beakers, or reservoirs, that have a defined so-called “equilibrium” volume.  Figure 2 shows how transport from left-to-right would be conceptualized with transport entering the inlet complex from the updrift beach, $Q_{in}$, and transporting to the Ebb shoal,$E$, then from $E$ to the Bypassing bar, $B$, then to the Attachment bar, $A$, and from there to the Shore, $S$.  As the first reservoir in the system, $E$, fills and its volume increases closer to the equilibrium (identified for all features with a subscript “$e$”), $V_{Ee}$, it begins to increase the transport to the next reservoir, $B$, proportionally.  Similarly, as $B$ fills towards its equilibrium, $V_{Be}$, it begins to transport more to $A$, and so on.
 
[[File:IRMPartIIFigure2.png|thumb|right|Figure 2. Definition sketch for IRM (modified from Kraus, 2002)]]
 
 
 
Equations for the Ebb shoal are presented below (modified from Kraus, 2002) to provide understanding of how the IRM is developed and explain the influence of the user-specified equilibrium volumes. For the full set of equations, the reader is directed to the CIRP Website and the [http://cirp.usace.army.mil/pubs/chetns/CHETN-IV-39.pdf CHETN-IV-39] publication.
 
The amount of material bypassed from any of the morphological forms is assumed to vary in direct proportion to the volume of the form (amount of material in a given reservoir) at the time of the calculation. Therefore, the rate of sand leaving $E$, $Q_{Eout}$, is specified as,


<big>
Dredging is one of the primary missions of USACE. Several hundred million cubic yards of sediment are dredged annually from U.S. ports, harbors, and navigation channels to maintain and improve the Nation's navigation system for commercial, national defense, and recreational purposes (USACE 2010). Dredging operations can have a significant impact on coastal morphological evolution (Stark 2012). Hence, the simulation of the coastal morphological features should also include dredging activities. In the past, dredging activities have been incorporated into CMS modeling studies by (1) interrupting the CMS simulation and modifying the bathymetry according to dredging activities and re-initializing the simulation (Beck and Legault 2012) or (2) limiting the simulation period to be within the dredging cycles (Sánchez and Wu 2011). To accurately simulate long-term coastal morphology change extending over multiple dredging cycles, a DM has been developed and implemented in the CMS. The module directly simulates dredging operations by removing and adding sediment to user-specified dredge and placement areas.
\begin{equation} \tag{1}
  Q_{Eout}=\frac{V_E}{V_{Ee}}Q_{in}
\end{equation}
</big>


in which $V_E$ is the volume of the ebb shoal at that time step, and $Q_{in}$ is taken to be constant (average annual rate).
==DREDGING MODULE (DM) OVERVIEW==
The DM simulates the dredging and placement of material by simply adjusting the bed elevations of user-defined dredge and placement areas on
the CMS-Flow grid. In the present version, the DM assumes a uniform bed composition and therefore is only recommended to be used with a single sediment size class. This limitation will be addressed in the subsequent version of the DM. There are multiple options for controlling how a dredging event is triggered, how the material is dredged, and how the material is placed. If CMS-Flow is coupled to CMS-Wave, the updated bathymetry is passed to the CMS-Wave grid at each steering interval. The DM is coupled to the hydrodynamics, waves, and sediment transport through the bed elevations. The dredging simulation can also be configured to simulate the construction of islands created through placement of dredged sediment. It is also possible to represent conditions in which the dredged sediment is placed in upland areas or in areas not represented in the CMS grid domain. A verification of the DM is presented in Reed & Reed (2014) for eight idealized test simulations to ensure correctness of input and output as well as mass conservation.
The DM is not intended to simulate the details of the dredging operation since it does not simulate processes such as the suspension of sediments during dredging, hopper dredging overflow, sediment dispersal during placement, etc. The primary purpose of the DM is to represent the morphologic changes due to dredging operations and estimate future dredging requirements in response to system modifications or changes in the environmental forcing.


The mass balance equation governing the change in $V_E$ can be expressed as,
==MODEL SETUP==
Dredging simulations are organized into dredge operations. Each dredging operation is characterized by a single dredge area and one or more placement areas. Multiple dredging operations may be specified in a simulation. For each dredging operation there are multiple options for controlling how a dredging operation is triggered, how the dredged material is removed, and how the dredged material is placed. Each dredging operation can use any of the user-defined dredge and placement areas.


<big>
All dredge operations use the same dredge update interval at which the dredging and placement occur. The dredged volume is calculated as the product of the time interval and the dredging rate. The dredging update interval is the same for all operations and is specified only once. The parameter
\begin{equation} \tag{2}
is only required for the explicit temporal solution scheme available in CMS; when the implicit scheme is used, the dredging update interval is automatically set to the hydrodynamic and sediment transport time step because this time step is relatively large.
  \frac{dV_E}{dt}=Q_{in}-{Q_{Eout}}
\end{equation}
</big>


where $t$ is time. Substituting Eqn. (1) into Eqn. (2),
The dredge and placement areas are defined by creating input datasets similar to a bottomfriction or hard-bottom dataset. The datasets are easily created and exported in XMDF file(s) (*.h5) in the SMS. Users should refer to the CMS User Manual for more information on how to create and export user-defined datasets (Sánchez et al. 2014). Cells within the dredge areas are assigned a depth indicating the maximum dredge depth. The dredge depth is the maximum depth to which a cell is dredged. Cells in the placement areas are assigned a value of 1. Cells outside of the dredge and placement areas are assigned a value of -999, which is the SMS convention for undefined values.


<big>
For each dredge area, the following must be defined:
\begin{equation} \tag{3}
#Dredging depths dataset (also defines dredging area)
  \frac{dV_E}{dt}=Q_{in}(1-\frac{V_E}{V_{Ee}})
#Criteria for triggering dredging
\end{equation}
#Dredging rate
</big>
#Method for determining where to dredge first
#Method for placement of dredge material.


If this is a new inlet (not required by the IRM), then $V_E(0)=0$, and the solution of (3) is
The four options for triggering dredging for a scenario are the following:
#If any cell in the source area has a bottom elevation above a threshold, as defined by the user.
#If the volume of sediment above the dredged depth is above a threshold, as defined by the user.
#If a certain percentage of the source area’s bottom elevation is above a threshold, with both the threshold and the percentage defined by the user
#Specification of a time window during which dredging can occur. Any dredged areas with elevations above the specified depth will be dredged during the specified time period. Multiple time periods can be specified. 


<big>
The dredging approach defines the order in which cells are dredged to the specified depth. There are two dredging approach options:
\begin{equation} \tag{4}
#During each dredging interval, the volume dredged initiates from the shallowest point in the source area first.
  V_E=V_{Ee}(1-e^{-at}), a=\frac{Q_{in}}{V_{Ee}}
#A dredging starting point is defined, and the volume dredged during each interval is taken from the cell closest to the starting point first and then progresses to cells that are farther away from the starting point. The starting point is defined by the user by specifying the cell ID that contains the starting point.
\end{equation}
</big>


The parameter a defines a characteristic time scale for the ebb shoal. For example, if $Q_{in} = 1 \times 10^5 m^3/$year and $V_{Ee} = 2 \times 10^6 m^3$, then $1/a = $ 20 years.  The shoal is predicted to reach 50% and 95% of its equilibrium volume after 14 and 60 years, respectively, under the constant imposed transport rate. These timeframes are on the order of those associated with development of inlet ebb shoals. Using user-defined transport rates, pathways and equilibrium volumes, the IRM develops and solves a system of coupled equations that describe the time-dependent evolution of each reservoir.  
If more than one placement area is specified for a dredging operation, then one of two methods is used to determine how the dredge material is distributed amongst the placement areas. In the first approach, the placement areas are filled in the order that they are defined in the advanced cards. All dredged material is placed in the first placement area until filled and then in the second area and so on. If all of the placement areas are filled to capacity, then the dredged material is assumed to be placed out of the grid system, and that volume is recorded. In the second scenario, the percentage of dredged material allocated to each placement area is defined during each dredging interval. If any placement area reaches capacity during the simulation, the dredged material is redistributed across the remaining placement areas, based on their relative percentages. If all of the placement areas fill during a simulation, then the material is placed outside of the grid domain. It is noted that if no placement area is specified, or the allocation does not sum to 100%, the remaining dredged volume is placed outside of the grid domain.


The significance of the equilibrium volume is apparent in the equations above.  Larger reservoirs with greater equilibrium volumes will not bypass sand as rapidly as smaller reservoirs (Eqn. (1)). For the ebb shoal proper plus bypassing bars, the equilibrium volumes can be estimated by using Walton and Adams (1976) relationships, as discussed in Part III of the IRM series. For reservoirs that are total sinks for sand, such as $Y$ and $O$ (Figure 1), the user can set these equilibrium volumes to very large values.  For sinks that are regularly dredged such as $C$ and $D$ (Figure 1), the equilibrium volumes can be set to a value which is representative of the typical dredging volume, which would imply that these reservoirs would not significantly bypass (or “leak”) sand until they begin to reach the typical dredging volume. Ideally, the user will have a history of growth and evolution of the Ebb shoal, Bypassing bars, Attachment bars, and other features with which to calibrate and validate the IRM for each project.
The following must be defined in each placement area:
#The placement limit, which is the maximum height that dredge material can be placed
#Method for determining where to start the material placement.  


==INTERFACE FEATURES==
There are two methods for specifying the placement limit for each placement area:
The IRM interface is a PC-based stand-alone program available for download from the CIRP website as discussed at the end of this CHETN. There are three main sections of the IRM interface, a Toolbar at the top of the page, an Alternatives window on the left-hand side, and the central Topology Window in which images can be displayed and the project formulated (Figure 3).  The Toolbar and Alternative Window are discussed with reference to Figures 4 and 5. The Topology Window is discussed in the Example Problem.
#Placement is limited to a user-specified thickness above the bed. If the material placed in a cell exceeds the specified thickness, then no more material will be placed in that cell.
#Placement is limited to a minimum water depth above the bed. If the material placed in a cell reduces the cell’s water depth to the specified limit, then no more material will be placed in that cell.


[[File:IRMPartIIFigure3.png|thumb|right|Figure 3. Overview of IRM PC Interface.]]
Both options can be defined for specifying the placement limit. In that case, the more limiting
condition will be used.


 
There are two options for determining where to start the material placement:
#The volume dredged is placed uniformly across the placement area.  Each cell is filled to the specified thickness or the placement water depth limit (also referred to as the placement limit).  When a cell reaches its placement limit, no more material is placed in that cell.
#A starting point is defined in the placement area. The volume dredged is placed in the cell closest to the point, and then the placement progresses to cells that are farther away from the starting point. The user defines the starting point by specifying the cell ID. Each cell is filled to the specified thickness or the placement water depth limit.


The top Toolbar is shown in the top-central portion of Figure 4, with a black rectangle outline. From left to right, each of these features is described below.
'''Input Cards.'''  The dredging simulations are specified using the advanced cards in the CMS menu and the dredge and placement areas specified using the SMS interface. The cards for the DM are described in Table 1. The first card is specified once, and the remaining cards are specified for each dredging scenario in a simulation. A specific simulation may not require all the cards.


[[File:IRMPartIIFigure4.png|thumb|right|Figure 4. IRM toolbar features and definitions.]]
==Table 1. Dredge module parameter specifications in the CMS==


{| class="wikitable"
! style="text-align: center; font-style: italic; width: 20%;" | Input
! style="text-align: center; font-style: italic; width: 40%;" | Format
! style="text-align: center; font-style: italic; width: 40%;" | Comments
|-
| Time interval for updating dredge algorithm
| [card=DREDGING_UPDATE_INTERVAL] [name=OpTimeInt, type=real, default=10]
[name=OpTimeIntUnits, type=char, options=TimeUnits, default=‘min’, optional=true]
| Only used for the explicit solver. The dredge interval is set automatically to the hydrodynamic time step for the implicit solver.
|-
| Dredging operation block
| [begin=DREDGE_OPERATION_BEGIN, name=DredgeOpBlock]
| Begin a dredging operation block structure.
|-
| Name of dredging operation
| [card=NAME, parent=DredgeOpBlock, optional=true]
| Assign a unique name to a dredging operation.
|- bgcolor="#fafeff"
| Dredge block
| [begin=DREDGE_BEGIN, name=DredgeBlock, optional=false]
| Begin a dredging block structure.
|- bgcolor="#fafeff"
| Dredge area and depth
| [card=DEPTH_DATASET, parent=DredgeBlock, optional=false]
[name=DredgeDepthFile, type=char, default=mpFile]
[name=DredgeDepthPathID, type=char, default=none]
| Specify the file name and path of the XMDF file with the dredging depth dataset. A depth value of -999.0 is assigned outside of the dredge area. mpFile is the CMS-Flow Model Parameter (*_mp.h5) file.
|- bgcolor="#fafeff"
| Dredging method
| [card=START_METHOD <nowiki>|</nowiki> METHOD, parent=DredgeBlock, optional=true]
[name=DredgeMethod, type=char, options=(SHALLOW,CELL), default=SHALLOW]
| Specify the method used to determine the order in which cells are dredged in the source area.
|- bgcolor="#fafeff"
| Starting Location for dredging
| [card=START_CELL, parent=DredgeBlock, optional=false]
[name=CellID, type=integer]
| CellID is the SMS cell ID of the starting location of the dredging operation. Only needed if START_METHOD is set to CELL.
|- bgcolor="#fafeff"
| Dredging rate for specified dredge scenario
| [card=(DREDGE_RATE <nowiki>|</nowiki> RATE) parent=DredgeBlock, optional=false]
[name=DredgeRate, type=real, optional=false]
[name=DredgeRate, type=char, options=(‘m^3/day’,‘m^3/hr’, ‘ft^3/day’,‘ft^3/hr’, ‘yd^3/day’,‘yd^3/hr’,) default=‘m^3/day’, optional=true]
| Specify the dredging rate. The dredging rate is constant for each dredging operation.
|- bgcolor="#fafeff"
| Trigger method
| [card=TRIGGER_METHOD, parent=DredgeBlock, optional=false]
[name=TriggerMethod, type=char, options=(DEPTH,VOLUME,PERCENT,
TIME_PERIODS), default=DEPTH]
| Specify the method for triggering dredging: The options are the following:
DEPTH: Dredging is triggered when the depth of a cell in the source area exceeds a depth threshold.
VOLUME: Dredging is triggered when the volume of sediment above the dredge depth in the source area exceeds a volume threshold.
PERCENT: Dredging is triggered when the a percentage of the cells in the source area exceed a threshold depth.
TIME_PERIODS: Dredging is triggered for user-specified time periods.
|- bgcolor="#fafeff"
| Trigger depth
| [card=TRIGGER_DEPTH, parent=DredgeBlock, optional=false]
[name=TriggerDepth, type=real]
[name=TriggerDepthUnits, type=char, options=LengthUnits, default=‘m’]
| Specify the dredging trigger depth. If speci-fied, TriggerMethod is set to DEPTH.
|- bgcolor="#fafeff"
| Trigger volume
| [card=TRIGGER_VOLUME, parent=DredgeBlock, optional=false]
[name=TriggerVolume, type=real]
[name=TriggerVolumeUnits, type=char, options=VolumeUnits, default=‘m^3’]
| Specifies the dredging trigger volume. If specified, then TriggerMethod is set to VOLUME.
|- bgcolor="#fafeff"
| Dredging time periods
| [card=DREDGE_TIME_PERIODS, parent=DredgeBlock, optional=false]
[name=Ntp, type=integer]
for(i=1:Ntp,
[name=Ts(i), type=real]
[name=Tf(i), type=real])
[name=DredgeTimePeriodUnits, type=char, options=TimeUnits, default=‘hr’]
| Specifies dredging time periods. If speci-fied, then TriggerMethod is set to TIME_PERIODS.
|- bgcolor="#fafeff"
| Placement distribution method
| [card=DISTRIBUTION, parent=PlacementBlock, optional=false]
[name=PlaceDistMeth, type=char, options=(PERCENT,SEQUENTIAL), default=SEQUENTIAL]
| Specifies the method for triggering dredg-ing. The two options are the following:
PERCENT: A percentage of the dredge material is assigned for each placement area. The percentages of all placements must sum up to 100.
SEQUENTIAL: The placements are filled sequentially in the order as listed.
|- bgcolor="#fafeff"
| Dredge block
| [begin=DREDGE_END, name=DredgeBlock]
| End a dredging block structure.
|- bgcolor="#FFFBFA"
| Placement block
| [begin=PLACEMENT_BEGIN, name=PlacementBlock, optional=false]
| Begin a placement block structure.
|- bgcolor="#FFFBFA"
| Placement area
| [card=AREA_DATASET, parent=PlacementBlock, optional=false]
[name=DredgeAreaFile, type=char, default=mpFile]
[name=DredgeAreaPathID, type=char, default=none]
| Specifies the file name and path of a XMDF file for the placement area. The placement area is given by nonzero values in the dataset. mpFile is the CMS-Flow Model Parameter (*_mp.h5) file.
|- bgcolor="#FFFBFA"
| Placement method
| [card=PLACEMENT_METHOD <nowiki>|</nowiki> METHOD, parent=PlacementBlock, optional=false]
[name=PlacementMethod, type=char, options=(UNIFORM,CELL), default=UNIFORM]
| Specifies the method for placement. The two options are the following:
UNIFORM: The dredge material is placed uniformed over the placement area.
CELL: The dredge material is placed start-ing at the user-specified point (location).
|- bgcolor="#FFFBFA"
| Percentage of material from dredge area
| [card=DISTRIBUTION_PERCENTAGE <nowiki>|</nowiki> DIST_PERCENTAGE, parent=PlacementBlock, optional=true]
[name=PlacementPercent, type=real]
| Specifies the percentage of material from the dredge area assigned to placement area. Only needed if the DISTRIBUTION card is set to PERCENTAGE.
|- bgcolor="#FFFBFA"
| Starting location for placement
| [card=START_CELL, parent=PlacementBlock, optional=false]
[name=CellID, type=integer]
| Specifies the SMS cell ID, CellID, of the starting location of the placement. Only needed if START_METHOD is set to CELL.
|- bgcolor="#FFFBFA"
| Limit on depth of disposed material in placement areas
| [card=DEPTH_LIMIT, parent=PlacementBlock,optional=false]
[name=PlacementLimit, type=real, parent= PlacementBlock)
[name=PlacementLimitUnits, type=char, options=LengthUnits, default=‘m’]
| Specifies the depth below water surface that material placement cannot exceed.
|- bgcolor="#FFFBFA"
| Limit on height of disposed material in placement areas
| [card=THICKNESS_LIMIT, parent=PlacementBlock, optional=false]
[name=ThicknessLimit, type=real, optional=true])
[name=PlacementLimitUnits, type=char, options=LengthUnits, default=‘m’]
| Specifies the maximum thicknesses above initial bed layer that placed material cannot exceed.
|- bgcolor="#FFFBFA"
| Placement block
| [end=PLACEMENT_END, name=PlacementBlock]
| Ends a placement block structure.
|-
| Dredge operation
| [end=DREDGE_OPERATION_END, name=DredgeOpBlock]
| Ends a dredging operations structure.
|}


* The purple box shows typical file and viewing tools, such as save, cut, paste, etc.
* Moving to the right, the next portion of the toolbar allows the user to select parts of the Topology window, all elements in the window, and lock a particular portion of the toolbar that will be repeated several times. For example, if several polygonal features were to be drawn in sequence, the lock and polygon would keep this feature active while drawing.  Clicking again on the lock removes the lock. 
* The next section of the Toolbar allows the user to draw a rectangular or polygonal morphologic feature. Once selected, a drop-down menu appears with various features identified. Another way to create these morphologic features is to use the area identified with the red box at the bottom of the toolbar, as described at the bottom of Figure 4. Note that the size, shape, and alongshore extent of the user-defined features do not influence the equilibrium relationships in the IRM. The planview footprint of these features only facilitates visualization.
* The area shown with a blue box on the Toolbar allows the user to draw pathways connecting transport rates to morphologic features, or feature-to-feature connections.  The first section is for pathways to the left, '''PL''', and the next section is for pathways to the right. Immediately to the right of the “'''PL'''” is the option to draw an input transport flux towards the left, '''QLI''', and an output transport flux, '''QL0'''.  Similarly, the next section allows pathways towards the right, '''PR''', input transport towards the right, '''QRI''', and an output flux towards the right, '''QR0'''.
* The area shown in a green box on the Toolbar provides an option to annotate the Topology window, such as with names for features shown in an image, the date of an image, or other information.  The project definition table summarizes information available about the project, and will be discussed later. When clicked, the runner button will execute the IRM for the conditions defined in the topology window, and the graphs (next icon) will change from a grayed-out image to a colored image when the run is completed. The user has the option to show a grid on the Topology window to better position and draw features.
* Finally, the last portion of the Toolbar allows the user to load an image as background to the Topology window, whether it is a *.jpg or other image or a shape file. Clicking the Layer button allows the user to see the images that are loaded and to reorder which ones are visible.  The last two buttons on the top Toolbar give information about IRM and provide help for specific features.


'''Output.''' The DM produces the following output:
#Setup File: The DM setup file, called dredge_module_setup.txt, is written at the beginning of the CMS simulation when dredging is turned on and contains a summary of the dredge scenarios and parameters defined in the advanced cards.
#Global Output: When a dredging scenario is defined, global output will be generated for the depth and morphology arrays. If sediment transport is active, the output will occur at the same intervals specified for morphology output. If sediment transport is not active, the morphology output will be written at the same interval as the water elevation output.
#Time-Series Output: A time-series output file in the comma delimited ASCII format will be generated for each dredging scenario defined in the simulation with the name DredgeDetailsOpNum_1.csv where the “_1” specifies the dredge scenario. The scenarios are numbered by the order in which they are defined in the advanced cards.


==EXAMPLE==
The St. Marys Entrance Channel extends 17.4 kilometers (km) (10.8 miles) offshore to the St. Marys River Entrance. The channel continues into Cumberland Sound up to Kings Bay Naval Submarine Base for a total length of 33.5 km (20.8 miles) (Figure 1). Presently, the channel is maintained at 15.5 meters (m) (51 feet [ft]) relative to mean low water (MLW) plus 3 ft of advanced dredging. The average annual dredged volume for the entrance channel since 1989 is approximately 968,000 cubic yards/year (yd<sup>3</sup>/year) with a range of 44,000 to over 3,000,000 yd<sup>3</sup>/year. [1] 


The Alternatives window is shown in Figure 5, and allows the user to view and edit the Topology Window. Right-click on an existing Alternative in this window to copy the IRM file into a duplicate Alternative #2. In this way an original set up can be altered with different pathways, engineering activities, or transport rates and differences readily viewed. The relationships between each morphologic feature can be viewed in the Relationships tab. Finally, fonts, colors and transparencies of features can be altered at the bottom of the window. Change colors and fonts, then select the features that are to be modified by using the selection buttons.  Then click on “Apply to Selected Objects” to have the changes implemented.
The CMS flow and wave models were configured to simulate dredging activities in the St. Marys Entrance Channel (i.e., the offshore portion of the channel). Bathymetry data were obtained from NOAA’s National Geophysical Data Center (NGDC) web site (NGDC 2014) for St. Marys Entrance, the adjacent offshore area, and in Cumberland Sound. A telescoping grid was constructed with variable grid cells ranging from 50 to 500 m (1640 ft) (Figure 1). A color contour map of the bathymetry is also shown in Figure 2, and the entrance channel is visible in the figure. The channel depths were set to 15.5 m (51 ft) at the beginning of the simulation.


A 1-year simulation for 2008 was used for the example. The model was forced with tide constituent data using the tidal consistent database available via SMS. Wind data were obtained from the NOAA meteorological station at Fernandina Beach (Station 8720030) (NDBC 2014). A CMS wave model was also configured for the same domain as the flow grid using constant 200 m grid spacing. Wave data from Wave Information Study (WIS) station 63401 (WIS 2014) were used for input to the wave model.


[[File:WTN17-1_Fig1.bmp|thumb|right|Figure 1. CMS-Flow computational grid.]]
[[File:WTN17-1_Fig2.bmp|thumb|right|Figure 2. Color contour bathymetry map for St. Marys Entrance, FL.]]


The flow and wave models were run using the implicit temporal scheme with the inline steering (coupling between flow and waves) option with a hydrodynamic time-step of 10 minutes (min), and a steering interval of 1 hour (hr). The DM was configured to simulate dredging of the outer
channel. The dredging and the placement areas are shown in Figure 3.


[[File:IRMPartIIFigure5.png|thumb|right|Figure 5. IRM Alternatives Window.]]
[[File:WTN17-1_Fig3.bmp|thumb|right|Figure 3. Dredge and placement areas and the dredge starting location.]]


    
The advanced cards used to activate the DM are listed in the example below:
<hr>
!Dredging Module Input Cards<br>
DREDGE_UPDATE_INTERVAL   900.0 'sec'<br>
DREDGE_OPERATION_BEGIN<br>
:NAME "MaintDREDGE"<br>
:DREDGE_BEGIN<br>
::DEPTH_DATASET  "Dredgearea.h5" "Datasets/Dredge_Area"<br>
::DREDGE_RATE  20000.0 'm^3/day'<br>
::START_METHOD  CELL !SHALLOW<br>
::STARTING_CELL  26475<br>
::DISTRIBUTION  SEQUENTIAL  !PERCENT | SEQUENTIAL<br>
::TRIGGER_METHOD  DEPTH  !DEPTH | VOLUME | PERCENT | TIME_PERIODS<br>
::TRIGGER_DEPTH  14.0 'm'<br>
:DREDGE_END<br>
:PLACEMENT_BEGIN<br>
::AREA_DATASET  "Dredgearea.h5" "Datasets/Placement_Area"<br>
::START_METHOD  UNIFORM  !STARTING_POINT<br>
::DEPTH_LIMIT  3.0 'm'<br>
:PLACEMENT_END<br>
DREDGE_OPERATION_END<br>
<hr>


In this section, a simple example for Rudee Inlet, Virginia is set up with hypothetical data to illustrate operation of the IRM and highlight features of the IRM interface, particularly use of the Topology Window. Part III of the IRM CHETN series applies the IRM to two other project sites to provide additional guidance on how to estimate quantities and pathways.
The file containing the identification of cells in the dredged and placement areas is “DredgeAreas.h5” with paths “Datasets/DredgeArea” and “Datasets/PlacementArea.” The dredge depth was set to 15.5 m (51 ft), and the triggering approach was set to the DEPTH method with a depth of 14.0 m (46 ft). The dredging rate was 20,000 cubic meters/day (m<sup>3</sup>/day) (26,159 yd<sup>3</sup>/day). The dredging started at the river entrance (cell ID 26475) and proceeded offshore. There was a single placement area. Dredged material was placed uniformly in each cell in the placement area and continued for each cell until the prescribed depth limit of 3.0 m (9.84 ft) was reached. A time-series plot of the dredging activities is shown in Figure 4. The relative offshore wave height during the simulation is shown in grey. The maximum height was 5 m (16.4 ft), and the sudden increase in the channel sediment volumes correlates well with the large wave events. The black dashed line (volume in channel) represents the sediment volume that is above the specified dredge depth in the entire dredge source area. The red line (volume ahead of dredge) is the sediment volume that has not been dredged yet in the section of the channel. For the first 33 days, these volumes are identical because dredging has not started. At day 33, the depth in the channel goes below the triggering depth of 14.0 m (45.93 ft) and dredging begins. The volume ahead of the dredge is the volume remaining to be dredged and decreases as the dredge progresses through the source area. The total volume in the dredge area also decreases but at a slower rate since sedimentation continues in the areas of the channel already dredged (i.e., behind the dredge). The sediment volumes occasionally increase in response to large wave events. The dredge reaches the end of the source area on day 93, when the sediment volume ahead of the dredge is reset to the same value as the total volume in the channel. At this point, the total dredged volume is approximately 1,150,000 yd<sup>3</sup> (879,238 m<sup>3</sup>). However, since sedimentation has been occurring behind the dredge, the triggering criteria of 14 m depth is exceeded only 1 week later, and the dredging cycle starts again.


[[File:WTN17-1_Fig4.bmp|thumb|right|Figure 4. Volume of sediment in channel and cumulative dredged as a function of time, St. Marys Entrance.]]
 
'''EXAMPLE, RUDEE INLET, VIRGINIA.''' When the IRM is installed, it creates a directory with two example cases, one for Sebastian Inlet, Florida and the other for Rudee Inlet.   
 
 
 
'''Step 1.''' Load the image for Rudee Inlet as background in the Topology Window by clicking on the camera in the upper toolbar, and browsing for the file “RudeeInlet comp.jpg.”  If the IRM was installed in the default directory, this image will be located at C:\Program Files\USACE\Reservoir\Data. Once the image is loaded, the user can click on the Layer button to see the path to any images that are loaded and reorder which image is visible, for multiple overlapping images.  The user can save the file as “ExampleRudee.rsv” (all IRM files are automatically saved with a *.rsv extension).
 
 
 
 
'''Step 2.''' Rudee Inlet has a weir jetty on the south (right) side of the image, with a deposition basin inside the weir jetty which is regularly dredged.  Net longshore sand transport (LST) is from right to left. First, draw the primary LST pathway by choosing the “transport to the left, into the system,” '''QLI''' button, and clicking and dragging the extent of this arrow coming into the south weir; double-click to end the arrow.  Similarly, draw the “transport to the left, out of the system”, '''QLO''' button.  These two buttons are now grayed-out in the upper toolbar.
 
 
 
 
'''Step 3.''' Now begin drawing morphologic features within the inlet system. Select “Draw polygonal feature" and choose a Depositional basin to draw inside the weir section of the project.  Continue drawing each morphologic feature, including the channel, ebb shoal, an offshore zone, flood shoal, and bay (Figure 6). If indices of a particular morphologic feature need to be moved, click on the feature and drag one of the corners (see ebb shoal in Figure 6 showing an indices being repositioned).
 
 
 
 
[[File:IRMPartIIFigure6.png|thumb|left|Figure 6. Example for Rudee Inlet.  Vertices on the ebb shoal illustrate selecting a corner and dragging it to reconfigure the feature.]]
 
 
 
 
'''Step 4.''' The next step is to draw transport pathways towards the left. The transport pathways should represent the directions sediment is transported in and around the inlet when transport is directed to the left. Select “Draw left pathway,” and begin dragging and double-clicking to create each pathway. Multiple pathways can extend from '''QLI''', '''QLO''', and any morphologic feature.  Once the '''PL''' button has been clicked that it remains locked; to unlock it, click on the lock button twice.  Pathways can be directed to the right, onshore, and offshore for conditions in which inlet processes cause local reversals of sediment that originated from the '''QLI''' source (Figure 6).
 
 
 
 
'''Step 5.''' The best way to enter data within the IRM is to double-click on the transport flux, pathway, or morphologic feature of interest and populate each data tab.  To begin, double-click on Qleft in and enter the transport rate shown in Figure 6.  Data can be entered for the remaining morphologic features and pathways as shown in Figure 6 by double-clicking on each.  Note that the sum of all pathways exiting a morphologic feature or transport flux must equal 1.0.
 
 
 
 
Click on the Project Definition button to see the data that has been entered.  The default time period for the IRM is to begin in 1900 and run for 100 years, until 2000.  Next add in the engineering activities for the Deposition basin and Channel as shown in Table 1.  Double-click on the Deposition basin and Channel and enter these data into the Events tab.
 
 
 
Measured data can be entered by double-clicking on a morphologic feature and selecting the Measurements tab. Add additional rows using the Add Row button at the bottom of the menu. Figure 7 shows hypothetical Ebb shoal volume measurements.
 
[[File:IRMPartIIFigure7.png|thumb|right|Figure 7. Entering measured data for the ebb shoal volume.]]
 
 
 
 
Once all data have been entered, click on the runner button in the top toolbar and let the program calculate.  The run is completed when the graph icon becomes active.
 
 
 
'''Step 6.''' To view the output, click on the graph icon and select which graphs to view.  Figure 8 shows output from several transport and morphologic features.  Dredging of the Channel and Deposition basin shows an effective “resetting” of these reservoirs, which then begin a new filling cycle. As would be expected, the output transport rate, $Q_{left out}$, increases with time as the ebb shoal and other morphologic features gain volume nearer to their equilibrium values.  At the end of 100 years,$Q_{left out} = 40,000 m^3$ /year which is 25% of the incoming rate.
 
 
 
 
[[File:IRMPartIIFigure8.png|thumb|right|Figure 8. IRM output graphs.]]
 
 
 
 
User-specified graphs can be created by combining multiple output types.  In the graph menu, select Add Graph, add a title and axis labels, then add features by clicking Add Row then using the drop-down menu to add the feature of interest (Figure 9a).  If measured data are available, add these by selecting Data Type as “Measurements,” selecting the morphologic feature for which there are data, and selecting the desired symbol (Figure 9b).
 
 
 
 
[[File:IRMPartIIFigure9a.png|thumb|left|Figure 9a. Creating a graph in IRM.]]
 
[[File:IRMPartIIFigure9b.png|thumb|left|Figure 9b. Showing the graph for the ebb shoal, channel, flood shoal, and ebb shoal measurements]]
 
==CONCLUSIONS==
The reservoir model of bypassing and ebb-shoal evolution requires input that is compatible with the amount and quality of data typically available in engineering and science studies. Such data are the longshore transport rate, which may be the net or gross rate depending on the inlet configuration; estimates of the equilibrium volumes of morphologic features; engineering activities during the period of interest; and qualitative understanding of sediment pathways at the particular inlet. The model predicts a delay in sand bypassing to the downdrift beach according to the properties of the morphologic system and longshore transport rate. The ratio of input longshore transport rate and equilibrium volume of the morphological feature is the main parameter governing volume change and bypassing rates. 
 
Part III of the IRM series discusses estimating input values and use of the IRM with project case studies.
 
 
 
 
==AVAILABILITY==
The IRM is available for download from the CIRP Website [http://cirp.usace.army.mil/products/?tab=5 Inlet Reservoir Model Products page].
 
==POINT OF CONTACT==
This Wiki-Note was prepared as part of the Coastal Inlets Research Program (CIRP) and was written by Dr. Julie D. Rosati (Julie.D.Rosati@usace.army.mil, Tel: 251-694-3719 Fax: 601-634-4314) of the U.S. Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL), 3909 Halls Ferry Road, Vicksburg, MS 39180; Dr. Mohamed Dabees, Humiston and Moore Engineers, Naples, FL; and Mr. Wayne Tanner, Applied Research Associates, Inc., Vicksburg, MS. Ms. Tanya Beck, Dr. Zeki Demirbilek, Ms. Ashley Frey, and Mr. Robert Thomas provided peer-review of this publication. For questions about this CHETN or information about the Coastal Inlets Research Program (CIRP), please contact the CIRP Program Manager, Dr. Rosati.


==SUMMARY==
A DM has been developed and implemented in the CMS. The module significantly enhances the capability of the model to support the USACE dredging operations at navigation channels by directly simulating dredging and placements within a CMS simulation. This allows the CMS to run over multiple dredging cycles and includes the morphological feedback that dredging produces on the morphology change. The implementation procedure for dredging operations was described, and an example simulation for conditions at St. Marys Entrance Channel, FL, has been provided to demonstrate the setup and results. Future enhancements to the DM include the representation of nonuniform sediments, spatially variable placement thicknesses or depths, and a user-friendly interface within the SMS.


==ACKNOWLEDGEMENTS==
This CHETN was prepared as part of the CMS work unit of the USACE CIRP. The technical note was reviewed by the CIRP program manager Dr. Julie D.
Rosati and by Dr. Honghai Li. Sincere appreciation is expres sed for their review comments and suggestions, which improved the content and clarity of this document. Files for the study may be obtained by contacting the authors.


==ADDITIONAL INFORMATION==
Questions about this CHETN can be sent to Dr. Alex Sánchez at (601-634-2027), FAX (601-634-3433), or e-mail: Alejandro.Sanchez@usace.army.mil. An
electronic copy of this document is available at http://chl.wes.army.mil/library/publications/chetn/.


==REFERENCES==
==REFERENCES==
* Dabees, M., and Kraus, N.C. 2004. Evaluation of ebb-tidal shoals as a Sand Source for Beach Nourishment: General Methodology with Reservoir Model Analysis. Proceedings, 17th National Conference on Beach Preservation Technology, CD-ROM, 21 p.
*Aquaveo. 2016. XMDF. Accessed 1 March 2017. http://www.xmswiki.com/wiki/XMDF.
 
*Beck, T. M., and K. Legault. 2012. St. Augustine Inlet, Florida: Application of the Coastal Modeling System, Report 2. ERDC/CHL TR-12-14. Vicksburg, MS: U.S. Army Engineer Research and Development Center.
* __________. 2005. General Methodology for Inlet Reservoir Model Analysis of Sand Management near Tidal Inlets. Proceedings Coastal Dynamics 2005, World Scientific, Inc., CD-ROM, 14 p.
*Buttolph, A. M., C. W. Reed, N. C. Kraus, N. Ono, M. Larson, B. Camenen, H. Hanson, T. Wamsley, and A. K. Zundel. 2006. Two-dimensional depth-averaged circulation model CMS-M2D: Version 3.0, Report 2, sediment transport and morphology change. ERDC/CHL TR-06-7. Vicksburg, MS: U.S. Army Engineer Research and Development Center.  
 
*Lin, L., Z. Demirbilek, H. Mase, J. Zheng, and F. Yamada. 2008. CMS-Wave: A nearshore spectral wave processes model for coastal inlets and navigation projects. ERDC/CHL TR-08-13. Vicksburg, MS: U.S. Army Engineer Research and Development Center.
* __________. 2008. Cumulative Effects of Channel and Ebb Shoal Dredging on Inlet Evolution in Southwest Florida, USA. Proceedings 31st International Conference on Coastal Engineering, World Scientific, Inc., 2,303-2,315.
*National Buoy Data Center (NDBC). 2014. National Data Buoy Center. Accessed 1 March 2017. http://www.ndbc.noaa.gov/station_page.php?station=frdf1.
 
*National Geophysical Data Center (NGDC). 2014. National Geophysical Data Center. Accessed 1 March 2017. http://www.ngdc.noaa.gov/.
* Kraus, N.C. 2000. Reservoir Model of Ebb-tidal Shoal Evolution and Sand Bypassing. J. Waterway, Port, Coastal, and Ocean Eng., 126(6), 305-313.
*Reed & Reed, LLC. 2014. Task 4b summary report: Development of a dredging module within the Coastal Modeling System. Prepared for Coastal Inlets Research Program (CIRP), United States Army Corps of Engineers.
 
*Sánchez, A., L. Lin, Z. Demirbilek, T. Beck, M. Brown, H. Li, J. D. Rosati, W. Wu, and C. Reed. 2014. Coastal Modeling System user manual. Accessed 1 March 2017. http://cirpwiki.info/images/d/d0/CMS_User_Manual.zip.
* Kraus, N.C., 2002. Reservoir Model for Calculating Natural Sand Bypassing and Change in Volume of Ebb-Tidal Shoals, Part I: Description. Coastal Hydraulics Engineering Technical Note IV-39, Coastal Inlets Research Program, U.S. Army Research and Development Center, Coastal and Hydraulics Laboratory, Vicksburg, MS, 14 pp.
*Sánchez, A., W. Wu, T. M. Beck, H. Li, J. Rosati III, R. Thomas, J. D. Rosati, Z. Demirbilek, M. Brown, and C. W. Reed. 2011a. Verification and validation of the Coastal Modeling System, report 3: Hydrodynamics. ERDC/CHL TR-11-10. Vicksburg, MS: U.S. Army Engineer Research and Development Center.
 
*Sánchez, A., W. Wu, T. M. Beck, H. Li, J. D. Rosati, Z. Demirbilek, and M. Brown. 2011b. Verification and validation of the Coastal Modeling System, report 4: Sediment transport and morphology change. ERDC/CHL TR-11-10. Vicksburg, MS: U.S. Army Engineer Research and Development Center.
* Zarillo, G.A., Kraus, N.C., and Hoeke, R.K. 2003. Morphologic Analysis of Sebastian Inlet, Florida: Enhancements to the Tidal Inlet Reservoir Model. Proc .Coastal Sediments ’03, CD-ROM, World Sci. Press and East Meets West Productions, Corpus Christi, TX ISBN-981-238-422-7, 14 p.
*Sánchez, A., and W. Wu. 2011. Nonuniform sediment transport modeling and Grays Harbor, WA. In Proceedings of the Coastal Sediments’11. Jacksonville, FL.
*Stark, J. 2012. The influence of dredging on the morphological development of the Columbia River mouth. M.S. thesis, Delft University of Technology, The Netherlands. U.S. Army Corps of Engineers (USACE). 2010. Actual dredging cost data for 1963-2009, longterm continuing cost analysis data. U.S. Army Corps of Engineers Institute for Water Resources Dredging Program. Accessed 1 March 2017.  http://www.navigationdatacenter.us/dredge/ddhisMsum.pdf.
*WIS 2014. Wave information studies. Accessed 1 March 2017. http://wis.usace.army.mil.  


<hr>
<hr>

Latest revision as of 20:50, 25 August 2020

CIRP-WN-17-1

by Chris Reed and Alejandro Sanchez


PURPOSE

This Coastal and Hydraulics Engineering Technical Note (CHETN) describes the implementation of a dredging module (DM) within the U.S. Army Corps of Engineers (USACE) Coastal Modeling System (CMS). The DM simulates one or more dredging operations during a CMS simulation and provides options for the dredging and placement of material. The DM may be used in studies such as estimating future dredging requirements, evaluating alternative dredging operations, and analyzing morphologic consequences of dredging operations. A coastal application at St. Marys Entrance Channel, FL, is provided to illustrate the setup procedure and demonstrate the model capability.

CITATION

Reed, C. and Sanchez, A. 2016. Coastal Modeling System: Dredging Module. Coastal and Hydraulics Engineering Technical Note ERDC/CHL CIRP-WN-17-1. Vicksburg, MS: U.S. Army Engineer Research and Development Center.

A pdf version of this document is available at the Defense Technical Information Center.

INTRODUCTION

The CMS, developed by the Coastal Inlets Research Program (CIRP), is an integrated suite of numerical models for simulating water surface elevation, current, waves, sediment transport, and morphology change in coastal and inlet applications. It consists of a hydrodynamic and sediment transport model, CMS-Flow, and a spectral wave model, CMS-Wave (Buttolph et al. 2006; Sánchez et al. 2011a, b; and Lin et al. 2008). The CMS is interfaced through the Surface-water Modeling System (SMS).

Dredging is one of the primary missions of USACE. Several hundred million cubic yards of sediment are dredged annually from U.S. ports, harbors, and navigation channels to maintain and improve the Nation's navigation system for commercial, national defense, and recreational purposes (USACE 2010). Dredging operations can have a significant impact on coastal morphological evolution (Stark 2012). Hence, the simulation of the coastal morphological features should also include dredging activities. In the past, dredging activities have been incorporated into CMS modeling studies by (1) interrupting the CMS simulation and modifying the bathymetry according to dredging activities and re-initializing the simulation (Beck and Legault 2012) or (2) limiting the simulation period to be within the dredging cycles (Sánchez and Wu 2011). To accurately simulate long-term coastal morphology change extending over multiple dredging cycles, a DM has been developed and implemented in the CMS. The module directly simulates dredging operations by removing and adding sediment to user-specified dredge and placement areas.

DREDGING MODULE (DM) OVERVIEW

The DM simulates the dredging and placement of material by simply adjusting the bed elevations of user-defined dredge and placement areas on the CMS-Flow grid. In the present version, the DM assumes a uniform bed composition and therefore is only recommended to be used with a single sediment size class. This limitation will be addressed in the subsequent version of the DM. There are multiple options for controlling how a dredging event is triggered, how the material is dredged, and how the material is placed. If CMS-Flow is coupled to CMS-Wave, the updated bathymetry is passed to the CMS-Wave grid at each steering interval. The DM is coupled to the hydrodynamics, waves, and sediment transport through the bed elevations. The dredging simulation can also be configured to simulate the construction of islands created through placement of dredged sediment. It is also possible to represent conditions in which the dredged sediment is placed in upland areas or in areas not represented in the CMS grid domain. A verification of the DM is presented in Reed & Reed (2014) for eight idealized test simulations to ensure correctness of input and output as well as mass conservation. The DM is not intended to simulate the details of the dredging operation since it does not simulate processes such as the suspension of sediments during dredging, hopper dredging overflow, sediment dispersal during placement, etc. The primary purpose of the DM is to represent the morphologic changes due to dredging operations and estimate future dredging requirements in response to system modifications or changes in the environmental forcing.

MODEL SETUP

Dredging simulations are organized into dredge operations. Each dredging operation is characterized by a single dredge area and one or more placement areas. Multiple dredging operations may be specified in a simulation. For each dredging operation there are multiple options for controlling how a dredging operation is triggered, how the dredged material is removed, and how the dredged material is placed. Each dredging operation can use any of the user-defined dredge and placement areas.

All dredge operations use the same dredge update interval at which the dredging and placement occur. The dredged volume is calculated as the product of the time interval and the dredging rate. The dredging update interval is the same for all operations and is specified only once. The parameter is only required for the explicit temporal solution scheme available in CMS; when the implicit scheme is used, the dredging update interval is automatically set to the hydrodynamic and sediment transport time step because this time step is relatively large.

The dredge and placement areas are defined by creating input datasets similar to a bottomfriction or hard-bottom dataset. The datasets are easily created and exported in XMDF file(s) (*.h5) in the SMS. Users should refer to the CMS User Manual for more information on how to create and export user-defined datasets (Sánchez et al. 2014). Cells within the dredge areas are assigned a depth indicating the maximum dredge depth. The dredge depth is the maximum depth to which a cell is dredged. Cells in the placement areas are assigned a value of 1. Cells outside of the dredge and placement areas are assigned a value of -999, which is the SMS convention for undefined values.

For each dredge area, the following must be defined:

  1. Dredging depths dataset (also defines dredging area)
  2. Criteria for triggering dredging
  3. Dredging rate
  4. Method for determining where to dredge first
  5. Method for placement of dredge material.

The four options for triggering dredging for a scenario are the following:

  1. If any cell in the source area has a bottom elevation above a threshold, as defined by the user.
  2. If the volume of sediment above the dredged depth is above a threshold, as defined by the user.
  3. If a certain percentage of the source area’s bottom elevation is above a threshold, with both the threshold and the percentage defined by the user
  4. Specification of a time window during which dredging can occur. Any dredged areas with elevations above the specified depth will be dredged during the specified time period. Multiple time periods can be specified.

The dredging approach defines the order in which cells are dredged to the specified depth. There are two dredging approach options:

  1. During each dredging interval, the volume dredged initiates from the shallowest point in the source area first.
  2. A dredging starting point is defined, and the volume dredged during each interval is taken from the cell closest to the starting point first and then progresses to cells that are farther away from the starting point. The starting point is defined by the user by specifying the cell ID that contains the starting point.

If more than one placement area is specified for a dredging operation, then one of two methods is used to determine how the dredge material is distributed amongst the placement areas. In the first approach, the placement areas are filled in the order that they are defined in the advanced cards. All dredged material is placed in the first placement area until filled and then in the second area and so on. If all of the placement areas are filled to capacity, then the dredged material is assumed to be placed out of the grid system, and that volume is recorded. In the second scenario, the percentage of dredged material allocated to each placement area is defined during each dredging interval. If any placement area reaches capacity during the simulation, the dredged material is redistributed across the remaining placement areas, based on their relative percentages. If all of the placement areas fill during a simulation, then the material is placed outside of the grid domain. It is noted that if no placement area is specified, or the allocation does not sum to 100%, the remaining dredged volume is placed outside of the grid domain.

The following must be defined in each placement area:

  1. The placement limit, which is the maximum height that dredge material can be placed
  2. Method for determining where to start the material placement.

There are two methods for specifying the placement limit for each placement area:

  1. Placement is limited to a user-specified thickness above the bed. If the material placed in a cell exceeds the specified thickness, then no more material will be placed in that cell.
  2. Placement is limited to a minimum water depth above the bed. If the material placed in a cell reduces the cell’s water depth to the specified limit, then no more material will be placed in that cell.

Both options can be defined for specifying the placement limit. In that case, the more limiting condition will be used.

There are two options for determining where to start the material placement:

  1. The volume dredged is placed uniformly across the placement area. Each cell is filled to the specified thickness or the placement water depth limit (also referred to as the placement limit). When a cell reaches its placement limit, no more material is placed in that cell.
  2. A starting point is defined in the placement area. The volume dredged is placed in the cell closest to the point, and then the placement progresses to cells that are farther away from the starting point. The user defines the starting point by specifying the cell ID. Each cell is filled to the specified thickness or the placement water depth limit.

Input Cards. The dredging simulations are specified using the advanced cards in the CMS menu and the dredge and placement areas specified using the SMS interface. The cards for the DM are described in Table 1. The first card is specified once, and the remaining cards are specified for each dredging scenario in a simulation. A specific simulation may not require all the cards.

Table 1. Dredge module parameter specifications in the CMS

Input Format Comments
Time interval for updating dredge algorithm [card=DREDGING_UPDATE_INTERVAL] [name=OpTimeInt, type=real, default=10]

[name=OpTimeIntUnits, type=char, options=TimeUnits, default=‘min’, optional=true]

Only used for the explicit solver. The dredge interval is set automatically to the hydrodynamic time step for the implicit solver.
Dredging operation block [begin=DREDGE_OPERATION_BEGIN, name=DredgeOpBlock] Begin a dredging operation block structure.
Name of dredging operation [card=NAME, parent=DredgeOpBlock, optional=true] Assign a unique name to a dredging operation.
Dredge block [begin=DREDGE_BEGIN, name=DredgeBlock, optional=false] Begin a dredging block structure.
Dredge area and depth [card=DEPTH_DATASET, parent=DredgeBlock, optional=false]

[name=DredgeDepthFile, type=char, default=mpFile] [name=DredgeDepthPathID, type=char, default=none]

Specify the file name and path of the XMDF file with the dredging depth dataset. A depth value of -999.0 is assigned outside of the dredge area. mpFile is the CMS-Flow Model Parameter (*_mp.h5) file.
Dredging method [card=START_METHOD | METHOD, parent=DredgeBlock, optional=true]

[name=DredgeMethod, type=char, options=(SHALLOW,CELL), default=SHALLOW]

Specify the method used to determine the order in which cells are dredged in the source area.
Starting Location for dredging [card=START_CELL, parent=DredgeBlock, optional=false]

[name=CellID, type=integer]

CellID is the SMS cell ID of the starting location of the dredging operation. Only needed if START_METHOD is set to CELL.
Dredging rate for specified dredge scenario [card=(DREDGE_RATE | RATE) parent=DredgeBlock, optional=false]

[name=DredgeRate, type=real, optional=false] [name=DredgeRate, type=char, options=(‘m^3/day’,‘m^3/hr’, ‘ft^3/day’,‘ft^3/hr’, ‘yd^3/day’,‘yd^3/hr’,) default=‘m^3/day’, optional=true]

Specify the dredging rate. The dredging rate is constant for each dredging operation.
Trigger method [card=TRIGGER_METHOD, parent=DredgeBlock, optional=false]

[name=TriggerMethod, type=char, options=(DEPTH,VOLUME,PERCENT, TIME_PERIODS), default=DEPTH]

Specify the method for triggering dredging: The options are the following:

DEPTH: Dredging is triggered when the depth of a cell in the source area exceeds a depth threshold. VOLUME: Dredging is triggered when the volume of sediment above the dredge depth in the source area exceeds a volume threshold. PERCENT: Dredging is triggered when the a percentage of the cells in the source area exceed a threshold depth. TIME_PERIODS: Dredging is triggered for user-specified time periods.

Trigger depth [card=TRIGGER_DEPTH, parent=DredgeBlock, optional=false]

[name=TriggerDepth, type=real] [name=TriggerDepthUnits, type=char, options=LengthUnits, default=‘m’]

Specify the dredging trigger depth. If speci-fied, TriggerMethod is set to DEPTH.
Trigger volume [card=TRIGGER_VOLUME, parent=DredgeBlock, optional=false]

[name=TriggerVolume, type=real] [name=TriggerVolumeUnits, type=char, options=VolumeUnits, default=‘m^3’]

Specifies the dredging trigger volume. If specified, then TriggerMethod is set to VOLUME.
Dredging time periods [card=DREDGE_TIME_PERIODS, parent=DredgeBlock, optional=false]

[name=Ntp, type=integer] for(i=1:Ntp, [name=Ts(i), type=real] [name=Tf(i), type=real]) [name=DredgeTimePeriodUnits, type=char, options=TimeUnits, default=‘hr’]

Specifies dredging time periods. If speci-fied, then TriggerMethod is set to TIME_PERIODS.
Placement distribution method [card=DISTRIBUTION, parent=PlacementBlock, optional=false]

[name=PlaceDistMeth, type=char, options=(PERCENT,SEQUENTIAL), default=SEQUENTIAL]

Specifies the method for triggering dredg-ing. The two options are the following:

PERCENT: A percentage of the dredge material is assigned for each placement area. The percentages of all placements must sum up to 100. SEQUENTIAL: The placements are filled sequentially in the order as listed.

Dredge block [begin=DREDGE_END, name=DredgeBlock] End a dredging block structure.
Placement block [begin=PLACEMENT_BEGIN, name=PlacementBlock, optional=false] Begin a placement block structure.
Placement area [card=AREA_DATASET, parent=PlacementBlock, optional=false]

[name=DredgeAreaFile, type=char, default=mpFile] [name=DredgeAreaPathID, type=char, default=none]

Specifies the file name and path of a XMDF file for the placement area. The placement area is given by nonzero values in the dataset. mpFile is the CMS-Flow Model Parameter (*_mp.h5) file.
Placement method [card=PLACEMENT_METHOD | METHOD, parent=PlacementBlock, optional=false]

[name=PlacementMethod, type=char, options=(UNIFORM,CELL), default=UNIFORM]

Specifies the method for placement. The two options are the following:

UNIFORM: The dredge material is placed uniformed over the placement area. CELL: The dredge material is placed start-ing at the user-specified point (location).

Percentage of material from dredge area [card=DISTRIBUTION_PERCENTAGE | DIST_PERCENTAGE, parent=PlacementBlock, optional=true]

[name=PlacementPercent, type=real]

Specifies the percentage of material from the dredge area assigned to placement area. Only needed if the DISTRIBUTION card is set to PERCENTAGE.
Starting location for placement [card=START_CELL, parent=PlacementBlock, optional=false]

[name=CellID, type=integer]

Specifies the SMS cell ID, CellID, of the starting location of the placement. Only needed if START_METHOD is set to CELL.
Limit on depth of disposed material in placement areas [card=DEPTH_LIMIT, parent=PlacementBlock,optional=false]

[name=PlacementLimit, type=real, parent= PlacementBlock) [name=PlacementLimitUnits, type=char, options=LengthUnits, default=‘m’]

Specifies the depth below water surface that material placement cannot exceed.
Limit on height of disposed material in placement areas [card=THICKNESS_LIMIT, parent=PlacementBlock, optional=false]

[name=ThicknessLimit, type=real, optional=true]) [name=PlacementLimitUnits, type=char, options=LengthUnits, default=‘m’]

Specifies the maximum thicknesses above initial bed layer that placed material cannot exceed.
Placement block [end=PLACEMENT_END, name=PlacementBlock] Ends a placement block structure.
Dredge operation [end=DREDGE_OPERATION_END, name=DredgeOpBlock] Ends a dredging operations structure.


Output. The DM produces the following output:

  1. Setup File: The DM setup file, called dredge_module_setup.txt, is written at the beginning of the CMS simulation when dredging is turned on and contains a summary of the dredge scenarios and parameters defined in the advanced cards.
  2. Global Output: When a dredging scenario is defined, global output will be generated for the depth and morphology arrays. If sediment transport is active, the output will occur at the same intervals specified for morphology output. If sediment transport is not active, the morphology output will be written at the same interval as the water elevation output.
  3. Time-Series Output: A time-series output file in the comma delimited ASCII format will be generated for each dredging scenario defined in the simulation with the name DredgeDetailsOpNum_1.csv where the “_1” specifies the dredge scenario. The scenarios are numbered by the order in which they are defined in the advanced cards.

EXAMPLE

The St. Marys Entrance Channel extends 17.4 kilometers (km) (10.8 miles) offshore to the St. Marys River Entrance. The channel continues into Cumberland Sound up to Kings Bay Naval Submarine Base for a total length of 33.5 km (20.8 miles) (Figure 1). Presently, the channel is maintained at 15.5 meters (m) (51 feet [ft]) relative to mean low water (MLW) plus 3 ft of advanced dredging. The average annual dredged volume for the entrance channel since 1989 is approximately 968,000 cubic yards/year (yd3/year) with a range of 44,000 to over 3,000,000 yd3/year. [1]

The CMS flow and wave models were configured to simulate dredging activities in the St. Marys Entrance Channel (i.e., the offshore portion of the channel). Bathymetry data were obtained from NOAA’s National Geophysical Data Center (NGDC) web site (NGDC 2014) for St. Marys Entrance, the adjacent offshore area, and in Cumberland Sound. A telescoping grid was constructed with variable grid cells ranging from 50 to 500 m (1640 ft) (Figure 1). A color contour map of the bathymetry is also shown in Figure 2, and the entrance channel is visible in the figure. The channel depths were set to 15.5 m (51 ft) at the beginning of the simulation.

A 1-year simulation for 2008 was used for the example. The model was forced with tide constituent data using the tidal consistent database available via SMS. Wind data were obtained from the NOAA meteorological station at Fernandina Beach (Station 8720030) (NDBC 2014). A CMS wave model was also configured for the same domain as the flow grid using constant 200 m grid spacing. Wave data from Wave Information Study (WIS) station 63401 (WIS 2014) were used for input to the wave model.

Figure 1. CMS-Flow computational grid.
Figure 2. Color contour bathymetry map for St. Marys Entrance, FL.

The flow and wave models were run using the implicit temporal scheme with the inline steering (coupling between flow and waves) option with a hydrodynamic time-step of 10 minutes (min), and a steering interval of 1 hour (hr). The DM was configured to simulate dredging of the outer channel. The dredging and the placement areas are shown in Figure 3.

Figure 3. Dredge and placement areas and the dredge starting location.

The advanced cards used to activate the DM are listed in the example below:

!Dredging Module Input Cards
DREDGE_UPDATE_INTERVAL 900.0 'sec'
DREDGE_OPERATION_BEGIN

NAME "MaintDREDGE"
DREDGE_BEGIN
DEPTH_DATASET "Dredgearea.h5" "Datasets/Dredge_Area"
DREDGE_RATE 20000.0 'm^3/day'
START_METHOD CELL !SHALLOW
STARTING_CELL 26475
DISTRIBUTION SEQUENTIAL !PERCENT | SEQUENTIAL
TRIGGER_METHOD DEPTH !DEPTH | VOLUME | PERCENT | TIME_PERIODS
TRIGGER_DEPTH 14.0 'm'
DREDGE_END
PLACEMENT_BEGIN
AREA_DATASET "Dredgearea.h5" "Datasets/Placement_Area"
START_METHOD UNIFORM !STARTING_POINT
DEPTH_LIMIT 3.0 'm'
PLACEMENT_END

DREDGE_OPERATION_END

The file containing the identification of cells in the dredged and placement areas is “DredgeAreas.h5” with paths “Datasets/DredgeArea” and “Datasets/PlacementArea.” The dredge depth was set to 15.5 m (51 ft), and the triggering approach was set to the DEPTH method with a depth of 14.0 m (46 ft). The dredging rate was 20,000 cubic meters/day (m3/day) (26,159 yd3/day). The dredging started at the river entrance (cell ID 26475) and proceeded offshore. There was a single placement area. Dredged material was placed uniformly in each cell in the placement area and continued for each cell until the prescribed depth limit of 3.0 m (9.84 ft) was reached. A time-series plot of the dredging activities is shown in Figure 4. The relative offshore wave height during the simulation is shown in grey. The maximum height was 5 m (16.4 ft), and the sudden increase in the channel sediment volumes correlates well with the large wave events. The black dashed line (volume in channel) represents the sediment volume that is above the specified dredge depth in the entire dredge source area. The red line (volume ahead of dredge) is the sediment volume that has not been dredged yet in the section of the channel. For the first 33 days, these volumes are identical because dredging has not started. At day 33, the depth in the channel goes below the triggering depth of 14.0 m (45.93 ft) and dredging begins. The volume ahead of the dredge is the volume remaining to be dredged and decreases as the dredge progresses through the source area. The total volume in the dredge area also decreases but at a slower rate since sedimentation continues in the areas of the channel already dredged (i.e., behind the dredge). The sediment volumes occasionally increase in response to large wave events. The dredge reaches the end of the source area on day 93, when the sediment volume ahead of the dredge is reset to the same value as the total volume in the channel. At this point, the total dredged volume is approximately 1,150,000 yd3 (879,238 m3). However, since sedimentation has been occurring behind the dredge, the triggering criteria of 14 m depth is exceeded only 1 week later, and the dredging cycle starts again.

Figure 4. Volume of sediment in channel and cumulative dredged as a function of time, St. Marys Entrance.

SUMMARY

A DM has been developed and implemented in the CMS. The module significantly enhances the capability of the model to support the USACE dredging operations at navigation channels by directly simulating dredging and placements within a CMS simulation. This allows the CMS to run over multiple dredging cycles and includes the morphological feedback that dredging produces on the morphology change. The implementation procedure for dredging operations was described, and an example simulation for conditions at St. Marys Entrance Channel, FL, has been provided to demonstrate the setup and results. Future enhancements to the DM include the representation of nonuniform sediments, spatially variable placement thicknesses or depths, and a user-friendly interface within the SMS.

ACKNOWLEDGEMENTS

This CHETN was prepared as part of the CMS work unit of the USACE CIRP. The technical note was reviewed by the CIRP program manager Dr. Julie D. Rosati and by Dr. Honghai Li. Sincere appreciation is expres sed for their review comments and suggestions, which improved the content and clarity of this document. Files for the study may be obtained by contacting the authors.

ADDITIONAL INFORMATION

Questions about this CHETN can be sent to Dr. Alex Sánchez at (601-634-2027), FAX (601-634-3433), or e-mail: Alejandro.Sanchez@usace.army.mil. An electronic copy of this document is available at http://chl.wes.army.mil/library/publications/chetn/.

REFERENCES

  • Aquaveo. 2016. XMDF. Accessed 1 March 2017. http://www.xmswiki.com/wiki/XMDF.
  • Beck, T. M., and K. Legault. 2012. St. Augustine Inlet, Florida: Application of the Coastal Modeling System, Report 2. ERDC/CHL TR-12-14. Vicksburg, MS: U.S. Army Engineer Research and Development Center.
  • Buttolph, A. M., C. W. Reed, N. C. Kraus, N. Ono, M. Larson, B. Camenen, H. Hanson, T. Wamsley, and A. K. Zundel. 2006. Two-dimensional depth-averaged circulation model CMS-M2D: Version 3.0, Report 2, sediment transport and morphology change. ERDC/CHL TR-06-7. Vicksburg, MS: U.S. Army Engineer Research and Development Center.
  • Lin, L., Z. Demirbilek, H. Mase, J. Zheng, and F. Yamada. 2008. CMS-Wave: A nearshore spectral wave processes model for coastal inlets and navigation projects. ERDC/CHL TR-08-13. Vicksburg, MS: U.S. Army Engineer Research and Development Center.
  • National Buoy Data Center (NDBC). 2014. National Data Buoy Center. Accessed 1 March 2017. http://www.ndbc.noaa.gov/station_page.php?station=frdf1.
  • National Geophysical Data Center (NGDC). 2014. National Geophysical Data Center. Accessed 1 March 2017. http://www.ngdc.noaa.gov/.
  • Reed & Reed, LLC. 2014. Task 4b summary report: Development of a dredging module within the Coastal Modeling System. Prepared for Coastal Inlets Research Program (CIRP), United States Army Corps of Engineers.
  • Sánchez, A., L. Lin, Z. Demirbilek, T. Beck, M. Brown, H. Li, J. D. Rosati, W. Wu, and C. Reed. 2014. Coastal Modeling System user manual. Accessed 1 March 2017. http://cirpwiki.info/images/d/d0/CMS_User_Manual.zip.
  • Sánchez, A., W. Wu, T. M. Beck, H. Li, J. Rosati III, R. Thomas, J. D. Rosati, Z. Demirbilek, M. Brown, and C. W. Reed. 2011a. Verification and validation of the Coastal Modeling System, report 3: Hydrodynamics. ERDC/CHL TR-11-10. Vicksburg, MS: U.S. Army Engineer Research and Development Center.
  • Sánchez, A., W. Wu, T. M. Beck, H. Li, J. D. Rosati, Z. Demirbilek, and M. Brown. 2011b. Verification and validation of the Coastal Modeling System, report 4: Sediment transport and morphology change. ERDC/CHL TR-11-10. Vicksburg, MS: U.S. Army Engineer Research and Development Center.
  • Sánchez, A., and W. Wu. 2011. Nonuniform sediment transport modeling and Grays Harbor, WA. In Proceedings of the Coastal Sediments’11. Jacksonville, FL.
  • Stark, J. 2012. The influence of dredging on the morphological development of the Columbia River mouth. M.S. thesis, Delft University of Technology, The Netherlands. U.S. Army Corps of Engineers (USACE). 2010. Actual dredging cost data for 1963-2009, longterm continuing cost analysis data. U.S. Army Corps of Engineers Institute for Water Resources Dredging Program. Accessed 1 March 2017. http://www.navigationdatacenter.us/dredge/ddhisMsum.pdf.
  • WIS 2014. Wave information studies. Accessed 1 March 2017. http://wis.usace.army.mil.

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