CMS-Flow/TideGates

Introduction

A tide gate is an opening structure built across a river or a channel in an estuarine system. By preventing saltwater intrusion to farm land and allowing freshwater drainage to the estuary, tide gates are commonly used for flow and flooding control, and salinity and sediment management. Because a tide gate is a significant component of hydrodynamic and sediment transport controls in the coastal zone, it is important to incorporate the structure and to simulate its effect in the CMS.

Usage of Tide Gages for CMS in the SMS

Early SMS versions (< 13.4)

Previous documentation (Link given below) described the formulation and implementation of Tide Gates in CMS, detailing input requirements for SMS versions up to 11.2. This implementation required hand-manipulation of the CMS-Flow parameter files to add in lists of cells and option values.

• Implementation of Structures in the CMS: Part IV, Tide Gate

Future SMS versions (13.4.x)

SMS 13.4 CMS-Flow model coverages.

A "Structures" coverage has been added beneath the CMS-Flow model option in SMS 13.4 and later. This one coverage will handle Tide Gates as well as three other types: Rubble Mounds, Weirs, and Culverts.

Tide Gates are added to this coverage with the placement of Feature Arcs.

1. Simply create a new feature arc within the new Structures coverage.
2. Select the arc and double click the arc to open the dialog.
3. Choose "Tide Gate" for the type and then enter the needed information on the right side of the dialog.
4. When finished, the "Structures" coverage will need to be applied to the CMS Simulation in order to export the appropriate cards to the parameter file.

Values needed by the CMS for each Tide Gate are listed in the table below. If there is a user-definable option in the dialog for the user to enter a value, the word 'Dialog' is shown in column 2, otherwise the words 'No dialog' are written in column 2. If the option uses a Table, that is shown in column 2.

List of tide gate structure parameters

Number of Cells	No dialog
Cell IDs	No dialog
Distribution Coefficient	Dialog
Orientation of Tide Gate	Dialog
Type of Weir	Dialog
Flow Coefficient Bay to Sea	Dialog
Flow Coefficient Sea to Bay	Dialog
Gate Opening Height	Dialog
Bottom Elevation of Tide Gate	Dialog
Calculation Method	Dialog
Schedule Operation Type	Dialog
Regular Start Time	Dialog
Regular Open Frequency	Dialog
Regular Open Duration	Dialog
Designated Start Time	Table
Designated Open Duration	Table

SMS will handle the assignment of the appropriate values for Number of Cells and Cell IDs. See the table below for any dependencies for the above parameters.

CMS-Flow specific information

The parameters/selections for each Tide Gate feature arc will be exported to the ‘.cmcards’ file in the form of a block of values.
This implementation is being tested with CMS 5.3.12 and later.

• The Tide gate parameter cards needed for each gate are added to a structure block with a corresponding BEGIN/END statement for each gate are listed in the table below.
• For readability and to be consistent with other cards in the .cmcards file, all values should start in column 36 and 3 spaces written between each value per line if more than one.

Cardname	Indent 2 spaces?	Type of value written	Dependent on	Notes
TIDEGATE_STRUCT_BEGIN	NO	N/A
CELL_IDS	YES	<int> <multiple int>		Total number of cells (n) followed by a list of all cell ids (from 1 to n).
DISTRIBUTION_COEFFICIENT	YES	<real>
ORIENTATION_SEA	YES	'NORTH', 'SOUTH', 'EAST', 'WEST'		Direction of Sea side
FLOW_COEFF_FROM_BAY	YES	<real>
FLOW_COEFF_FROM_SEA	YES	<real>
OPENING_HEIGHT	YES	<real>		How large the opening for the gate is.
BOTTOM_ELEVATION	YES	<real>		Positive is upward
METHOD	YES	1 or 2		1= Approach 1, 2= Approach 2 (see literature)
SCHED_OPERATION_TYPE	YES	'REG', 'DES', 'EBB', 'UCG'		'REG' - regular time interval 'DES' - designated times and durations 'EBB' - open gate for ebb tide, close for flood 'UCG' - uncontrolled gate
REG_START_TIME	YES	<int>	Operation type == 'REG'	Start time (hour)
REG_OPEN_FREQUENCY	YES	<int>	Operation type == 'REG'	Opening frequency (hour)
REG_OPEN_DURATION	YES	<int>	Operation type == 'REG'	Open duration (hour)
NUM_DESIGNATED_TIMES	YES	<int>	Operation type == 'DES'
DES_START_TIME	YES	multiple <int>	Operation type == 'DES'	Start time (hour) Repeated for number of designated times
DES_OPEN_DURATION	YES	multiple <int>	Operation type == 'DES'	Open duration (hour) Repeated for number of designated times
TIDEGATE_STRUCT_END	NO

An example configuration for two tide gates is shown below:

TIDEGATE_STRUCT_BEGIN
  CELLS                             3  20 50 70    
  DISTRIBUTION_COEFFICIENT          0.9
  ORIENTATION_SEA                   NORTH        !NORTH, EAST, SOUTH, WEST
  FLOW_COEFF_FROM_BAY               0.5 
  FLOW_COEFF_FROM_SEA               0.46  
  OPEN_HEIGHT                       2.0  
  BOTTOM_ELEVATION                  -1.0  
  METHOD                            1            !1= Approach 1, 2= Approach 2
  SCHED_OPERATION_TYPE              REG          !REG, DES, EBB, or UCG
  REG_START_TIME                    0            !-- This is elapsed hours from start (immediately on first day)
  REG_OPEN_FREQUENCY                18           !-- Reopen every 18 hours after the initial opening
  REG_OPEN_DURATION                 6            !-- Keep gate open for 6 hours each time.
TIDEGATE_STRUCT_END
TIDEGATE_STRUCT_BEGIN
  CELLS                             2  600 620
  DISTRIBUTION_COEFFICIENT          0.8
  ORIENTATION_SEA                   NORTH        !NORTH, EAST, SOUTH, WEST
  FLOW_COEFF_FROM_BAY               0.45 
  FLOW_COEFF_FROM_SEA               0.4  
  OPEN_HEIGHT                       1.5  
  BOTTOM_ELEVATION                  -1.5
  METHOD                            1            !1= Approach 1, 2= Approach 2
  SCHED_OPERATION_TYPE              DES          !REG, DES, EBB, or UCG
  NUM_DESIGNATED_TIMES              3
  DES_START_TIME                    15 35 56     !-- Open gate at 15, 35, and 56 hours after start of run
  DES_OPEN_DURATION                 6  7  6      !-- Keep gate open for 6, 7, and 6 hours, respectively.
TIDEGATE_STRUCT_END

Idealized grid showing bathymetry and the location of the applied tide gate structure.

Example Case

One example case for Tide Gates is described below and example files are provided in the next section. This example introduces an idealized grid with a smaller bay area and medium sized off-shore area. A segment through the inlet is designated as a tide gate structure which has the following regular (recurring) schedule:

• First open time - 0.00 hours (immediately at start of simulation).
• Open duration - for 12 hours after each open.
• Open frequency - every 24 hours.

The grid and bathymetry is shown in the figure to the right with the tide gate structure identified by the feature arc in the inlet.

Input and output files

Below are the prospective project and input/output files for SMS 13.4/CMS 5.3.12 which show the REGULAR tide gate schedule:

• SMS 13.4 Project (datasets and project only)
• Example Input files to CMS

Last update 11/26/2024

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