
//
// UNIT HYDROGRAPH HELP FILE
//         NOHRSC
//
// This help file was created on July 21, 1998
// by Peter Moarefi
// Additions by Anders Nilsson on November 10, 1998
// 
// Version 1.11    - Dec. 15, 1998
// Version 1.12    - Jan. 14, 1999
// Version 1.13    - Jan. 29, 1999
//                 - Apr. 14, 1999
// Version 1.15    - May   2, 1999
// Version 1.16    - Aug. 26, 1999
// Version 1.17    - Nov. 22, 1999
// Version 1.18    - Dec. 21, 1999
// Version 1.20    - May  10, 2000
// Version 1.21    - May  02, 2001
// Version 1.22    - May  02, 2001
// Version 1.23    - Feb. 21, 2002
// Version 1.24    - Mar. 20, 2002
// Version 1.25    - Jun. 14, 2004
// Version 1.26    - Apr. 19, 2005
// Version 1.27    - Oct. 24, 2007
// Version 1.28    - Jun. 15, 2009

/ONE Unit Hydrograph Overview
Unit Hydrograph Overview

Unit Hydrograph was developed to provide National
Weather Service River Forecast Centers (RFC's) with an 
objective tool for computing unit hydrographs for basins
within their respective area of responsibility. The 
software allows the user to generate, edit, and compare
unit hydrographs.

The current version of Unit Hydrograph provides the
ability to produce synthetic unit hydrographs using two
basic methods:

1) The SCS Dimensionless Unit Hydrograph
2) A time-area approach

Although a number of internal parameter options allow 
considerable flexibility in the derivation of the unit 
hydrographs.

/ONE - Generating a Hydrograph
Generating a Unit Hydrograph


1. Open a basin layer, under File->Open Basin Layer...
   The basin layer should appear on the view screen.
2. Select the basin for which you want to create a unit
   hydrograph. You can either select the basin by clicking
   inside or by selecting the basin name from a list of 
   available basin names. Selecting a basin will start
   Unit Hydrograph's preprocessing checks.
3. Once this is complete, the "Generate" menu will
   become available, and you will be able to select a
   method to generate a unit hydrograph. A new window
   with a black background will appear.
4. Click File->"New" to bring up a dialog of parameters,
   which may vary depending on the method chosen.  Most or
   all of the parameters will have default values.
5. Accept of alter the parameters of your choice, and
   click on "Generate." The time to generate the unit
   hydrograph will be very dependent on the size of the
   basin and the parameters selected.
6. A unit hydrograph will appear in the window. You may 
   query key characteristics via the View->Detail, or
   view the mass curve via View->Options, and then 
   selecting the mass curve box.
7. Don't forget to save...you can save the hydrograph
   to disk/database with File->SaveAs. The file will
   be saved in a directory specified in the config
   file. If no directory is specified, the file will be
   saved in the same directory as the Unit Hydrograph 
   application.
   
/ONE - Generation Methods
Generation Methods

SCS Methods - 

The Soil Conservation Service (SCS) dimensionless unit
hydrograph procedure is one of the most well known methods
for deriving synthetic unit hydrographs in use today.  
References for this method can be found in most hydrology
textbooks or handbooks. It was derived based on a larger
number of unit hydrographs from basins that varied in 
characteristics such as size and geographic location. The 
unit hydrographs were averaged and the final product was 
made dimensionless by considering the ratios of (flow/peak
flow) on the ordinate axis and (time/time to peak) on the
abcissa.

There are 2 basic methods of estimating the response time
of the basin within the unit hydrograph software for the
SCS method.  The 2 basic methods are 1) a regression 
equation and 2) a segmental approach.

Regression Method - 
   Uses a regression equation to directly estimate the 
   basin lag time.  The required inputs are length of the
   longest drainage path, slope, and the SCS curve number.
   At the present time, the Unit Hydrograph software will 
   automatically calculate the basin area, the longest
   drainage path, and the  slope.  The user must enter the
   curve number.

Segmental Methods:
   In the segmental velocity or segmental approach, the
   parameter being estimated is essentially the time of
   concentration or longest travel time within the basin.
   In general, the longest travel time corresponds to the
   longest drainage path; however, there may be some
   situations and basin configurations that allow for
   some shorter travel distances to have longer travel 
   times, due to land use and/or flow type. The sum of 
   all the travel times represents the time of 
   concentration. Under the segmental approach, there are
   several options for estimating the travel time across 
   each cell, which are detailed below.
	   
Constant Velocity -
   This method assumes that water moves across all
   cells at a user-defined constant velocity.
Landcover based - 
   NOT CURRENTLY AVAILABLE.
   This calculation takes in data from a land use
   raster specified in the config file, which more 
   accurately determines the velocity of overland 
   water flow. K-values for the specific landcover
   types are specified by the user (or defaults).
Flow Type based -
   This method uses different velocities for 
   differing types of overland flow. Velocities for each
   type of flow are specified by the user (or defaults).
Accumulation based -
   This method calculates velocity as a factor of
   the flow accumulation. 

Time-Area Methods - 

Time-area unit hydrograph theory establishes a relationship
between the travel time and a portion of a basin that may
contribute runoff during that travel time. In a time-area
approach, the watershed is traditionally broken into areas of
approximately travel time.  These lines of equal travel time
are known as isochrones. The mean travel time of each sub-area
is calculated and the resulting time-area curve is produced.
Many "time-area" methods utilize a common, basic approach in
determining the final unit hydrograph.  Summing the incremental
areas and corresponding travel times enables the formation of a 
cumulative time-area curve.  Thus, the total time can be thought
of as the time of concentration of the watershed with 100% of
the basin area being accounted for at the time of concentration.
Each of the partial areas (between isochrones) responds in the
time associated with that area.  The volume of water of each 
area reaches the outlet at the travel time associated with that
area.  The time-area histogram is really a translation 
hydrograph because the volume of water on each area within the
basin is simply "translated" to the outlet using the associated
travel time for the translation time.  A this point, a unit 
hydrograph (in discrete form) exists.  This "instantaneous" 
unit hydrograph is the result of 1-inch of instantaneous excess
precipitation being placed on the individual areas and then
translated to the outlet of the basin, arriving at the time 
associated with the travel time of area. Watersheds also have 
the ability to store and delay the flow that passes through.  
This storage effect is seen in reservoirs as they attenuate a
hydrograph.  In order to model this effect, the translation unit
hydrograph is routed through a linear reservoir.  There are 
several alternatives available when using the time-area
approach.
 

Classic Time Area -
   This approach breaks up a basin into approximate
   areas of equal travel time (isochrones). The mean
   travel time of each area is discretely calculated and
   then routed through a linear reservoir to create a
   flow curve.   		   
Distributed Time Area -
   This method is identical to the Classic approach,
   except that each cell is individually through a linear
   reservoir, instead of being grouped into a mean.	   
Fully Distributed -
   This method routes and delays water over each cell
   and divides the cell into an equal isochrones of 
   travel times. This calculation of lag and flow is 
   done for each cell and culminates at the outlet 
   point, where a final flow curve is produced. This 
   method reflects intricate topography and is best 
   used with such. However, it may be overkill for more
   simple basins.
	   


/ONE - Generation Parameters
Generation Parameters

The following is a list of the various parameters, with a
short explanation, that can be changed in order to create
a new hydrograph:

Channel - 
   This dialog asks what the user wants the channel
   definition to be. The choices are the EPA RF1 river
   reach file or the flow accumulation layer, with an
   accumulation threshold indicating a channel.
Shape - 
   The SCS method hydrograph can either be a triangle or 
   gamma function curve fitted to the peak 
   flow value.
Duration -
   (in hours) over which the 1" of water falls. 
R(eservoir) Factor -
   Reflects the storage capacity of the basin.
Time Interval - 
   (in minutes) for which the calculations on the basin
   will be done. The program may prompt you to enter in a 
   smaller time interval if necessary. However, take 
   note that the smaller the interval, the more memory 
   that will be required and the longer time that it 
   will take for the hydrograph to generate.
Segments per Cell -
   This is the number of "isochrones" (or time segments)
   that each cell is subdivided into.
Coefficient -
   This "peaking factor" reflects the basin's ability to 
   retain and delay the flow in the SCS method. 
Curve Number -
   Soil Conservation Service runoff curve number.  Used in
   the SCS regression equation

/ONE - Velocity Parameters
Velocity Parameters

This dialog is accessible from the top menu through
Options->Velocity Parameters, or via a button in the 
File->New (hydrograph) dialog. This display lists the
various constants that are used in the segmental velocity
"submethods." 

Constant Velocity submethod:
   - Velocity is the rate at which the water flows over
    all the cells.
    
Landcover based submethod:
   -
   
Flow Type based submethod:
   - Overland flow velocity is assumed to exist for a
     "short distance" on all cells that have no upstream
     cells (i.e. the ridgetop cells). 
   - Swale flow velocity is assumed for overland flow
     routes which are well-defined swales by elevation 
     contours, but is not a channel.
   - Channel flow velocity is assumed for tributaries and
     such, either defined by EPA river reach files or by
     flow accumulation values.
   - Overland distance (between 0-100m) is the "short
     distance" for which Overland flow exists.
     
Accumulation based submethod 
   - Mean Velocity is the base velocity value which is
     multiplied by a factor calculated from the upstream
     drainage area, or flow accumulation. 
   - (Channeling)
     Channel accum. is the threshold value for a channel
     as defined by flow accumulation. It defaults at half
     the basin area.

/ONE IHABBS and Unit Hydrograph
IHABBS and Unit Hydrograph

IHABBS is important to the Unit Hydrograph program in that
it creates the basin boundaries that latter program uses. 
Unit Hydrograph takes the geometry created by IHABBS and 
constructs a unit hydrograph by routing water over the 
surface of the basin.
    However, the resulting hydrograph is rendered 
inaccurate if the basin geometry is changed after the 
hydrograph is generated. Deleting the basin has a similar
effect. If the user makes changes to the basin layer that
impacts generated hydrographs, IHABBS 3.0 will flash a 
warning screen before the layer can be saved. This dialog
will show the altered basins and the hydrographs that will
be affected. It is then up to the user to recalculate 
those hydrographs. 
    This can be done by opening the altered basin layer 
and selecting the basin and method type. Open the
hydrograph and use the Recalculate option to update the
unit hydrograph. Then Save the changes.


/ONE Hydrograph Method Menu Options
Hydrograph Method Menu Options

File - New:
    Displays a parameter dialog for generating a synthetic
    unit hydrograph. Options displayed here will vary by
    method, though all will prompt you to select a velocity
    submethod. Clicking "Generate" will start the hydrograph
    calculation process.

File - Open:
    This enables the user to select and open a hydrograph
    that was created for the opened basin.

File - Close:
    This will close the displayed hydrograph and clear the
    window, whether saved or not.
 
File - Save:
    This will save the current opened hydrograph if it has
    been altered. If the hydrograph has not been saved 
    prior, it will prompt for a filename.
    
File - SaveAs:
    This will save the current opened hydrograph with a 
    user-defined filename.

File - Exit:
    Closes the specific method window, and does not save
    any opened hydrograph for that method.
    
Edit - Undo Adjustments:
    This restores the hydrograph to its original, calculated
    form. 
    
Edit - Adjust Hydrograph:
     Allows the user to "tweak" the hydrograph to their own 
     preference. It allows the user to directly change the
     base and peak time of the hydrograph. Flow is modified
     accordingly. 

Edit - Recalculate:
     Allows the user to recalculate an opened hydrograph. This
     newer hydrograph can be saved over the old one. Useful if
     the basin geometry changes.
     
Query - Query Hydrograph:
      Allows the user to find an exact point on the flow
      curve, either by clicking on different points, or by
      using the left and right arrow keys.
      
View - Detail:
      Brings up a small window that show the principal
      statistics of the flow curve. The time of concentration,
      base time, lag time, peak time, peak flow, and basin 
      area are all displayed.

View - Options:
      This toggles whether or not the user wants to view the 
      accompanying mass volume curve to the hydrograph. The
      other useful option here is "Superimpose," which allows
      the user to view several hydrographs on top of each
      other. This uses the opened window x & y scale to view
      the successive hydrographs.
      
      
      	
/ONE Menu Options
Menu Options

The Menubar and its pulldown menu options are explained
herein:

File - Open Basin Layer:
    Select and open a basin layer. The list of
    the basin layers are read from the Informix data-
    base and listed for selection. Once a basin is
    selected, its layer is automatically displayed.
    
File - Close Basin Layer: 
    Closes the opened basin layer and frees
    all associated memory files.
    
File - View Hydrograph :
    This enables the user to quickly view as a reference 
    any hydrograph that they have created for their RFC.
    A dialog will appear with a listing of openable
    hydrographs. This dialog can be kept open in the
    background, and the removal or addition of new
    hydrographs will be updated on this list. The opened
    hydrograph cannot be altered or saved from the
    Reference Hydrograph window.
    
File - Remove Hydrograph :
    Deletes a previously saved hydrograph file with the
    corresponding database entry. This can also be used to
    query which layers correspond to a particular
    hydrograph. (Make sure you don't click on Remove if
    you do this.)
    
File - Export Hydrograph:
    Select and export a saved unit hydrograph
    in an ASCII format compatible with NWSRFS Card Format.
    Note that the exported flow values are sampled directly
    from the flow curve. The resulting columns may not
    conserve the mass of the original flow curve.
    
File - Exit :
    Free all resources, and exit the application.
    
Select - Basin Using Mouse :
    Before any computation is performed, or any method is
    selected, a basin from the basin layer must be
    selected. This options allows the user to select a
    visible basin using the pointing device, and clicking
    with the mouse left button. Selecting a basin will start
    the Unit Hydrograph's preprocessing checks. Once the
    basin is selected and the preprocessing complete, the 
    basin is then high-lighted for visual clearity.
    
Select - Select Basin from List :
    Before any computation is performed, or any method is
    selected, a basin from the basin layer must be
    selected. This options allows the user to select a
    basin from the list of all basins in the opened basin
    layer. Selecting a basin will start the Unit
    Hydrograph's preprocessing checks. Once the basin is
    selected and the preprocessing complete, the basin is
    then high-lighted for visual clearity.
    
Generate - SCS Method :
    Once a basin is selected, this option opens a unit
    hydrograph window displaying a blank canvas letting the
    user generate unit hydrograph based on the SCS method.
    
Generate - Classic Time Area Method :
    Once a basin is selected, this option opens a unit
    hydrograph window displaying a blank canvas letting the 
    user generate unit hydrograph based on the Time Area     
    method.
    
Generate - Distributed Time Area Method :
    Once a basin is selected, this option opens a unit 
    hydrograph window displaying a blank canvas letting the
    user generate unit hydrograph based on the Distributed 
    Time Area method.
    
Generate - Fully Distributed Method :
    Once a basin is selected, this option opens a unit 
    hydrograph window displaying a blank canvas letting the 
    user generate unit hydrograph based on the Fully 
    Distributed method.
    
Options - Display Options
    The Display Options dialog permit the user to set 
    application-wide parameters:
        System Units:    English / Metric.
        Degree Format:   Decimal / Degrees Minutes Seconds
        Rescale On Zoom: Rescales full gray scale to 
                         zoomed in portion of the viewer.
        Display Legend : "No" provides more viewing area
        		 for the map.
        		 
Options - Velocity Parameters
    This dialog allows the user to set velocity constants
    that are used in some of the Unit Hydrograph
    computations. The constants listed with the
    corresponding methods are not used in the other
    methods. Clicking Apply after your changes will 
    put the new constants into effect, while Cancel will
    undo any changes that you might have just made.  
    
Options - Landcover based K-factors
    Just like the Velocity Parameters dialog, this allows
    the user to set the velocity constants that are used
    with the "Landcover based" option when generating
    hydrographs. If you do not have a Land Use raster, don't
    worry about this. Clicking Apply after your changes will
    put the new constants into effect, while Cancel will
    undo any changes that you might have just made. 		

Query - Basins
    This dialog allows the user to find information
    concerning the opened basin layer. To find information
    on a specific basin in the basin layer, click "Query,"
    and then click inside the basin on the map. This tool
    displays the ID properties as defined and calculated 
    by IHABBS, as well as listing the connecting basins
    immediately upstream and downstream. 
     
Query - Rasters
    This dialog allows the user to query all the raster
    values at a specific point. To find raster information
    at point, click "Query," and then click on that point 
    on the map. Layers not available will be grayed out,
    or in a worse case, an error message may appear stating 
    that the program is having problems accessing a layer.
    In this case, please consult user support.
    
View  - Features
    This dialog turns on and off the features displayed
    in the viewer. One raster can be shown at a time
    (or otherwise none), while multiple vector layers
    can be shown at a time. Layers that are not available
    will be grayed out. The Unit Hydrograph starts up with
    only the RFC layer shown (and the Basins layer, if a 
    default is specified in the config file).

View  - Colors
    Set Vector Colors
    Set Point  Colors
    Set Hydrograph Color
    Set Background Color
    
    These four dialogs allow the user to customize the
    colors shown in Unit Hydrograph. Set Vector colors 
    allows the user to assign one of fourteen colors defined
    in the configuration file to shown vector layers.
    Set Hydrograph color changes the color (from white) to any
    hue as defined by scrollbars of red, green, and blue.
    The same technique is applied to Set Background Color, 
    which in addition to the map viewer background color, is 
    also the color seen for older hydrographs when "Superimpose"
    is turned on.
    


/ONE - View->Features
View - Features

Purpose 

To control what data is displayed in the display 
region.

Usage

Select a raster image and as many vector drawings
as you like for display. Raster images may be
displayed with or without vector drawings. Vector
drawings may be displayed with or without raster
images. Only one raster image may be displayed at
once. As many vector drawing as you like may be 
displayed at once.

Vector drawings will always be displayed over raster
images. Raster images will never obscure vector
drawings.  Vector drawings are displayed in the 
order that they were selected.

Relationships

Certain raster images represent a continuous surface
of values. DEMs, for instance, depict elevations from
less than 0 meters to several thousand meters. Your
computer is capable of displaying only a relatively
small number of monotonic colors - somewhere between
200 and 250 monotonic colors. Not enough colors to
see much detail.

We've put in a feature which allows the program to
compute a new monotonic color table each time the
limits of the display region changes. As you zoom in
more and more detail in the raster image is revealed
when this option is invoked. See Options - Display
Options for details.


Hints

Some of the GIS layers take longer to display than
others. You may find it useful to wait until you've
tightened your view before displaying time consuming
GIS layers.  Also, raster GIS layer color table
scaling is a feature you may wish to use with
discretion if image rendering times are unacceptable.

Since vector drawings are displayed in the order 
that they were selected, display the most important
vector drawing last. Otherwise it will be obscured by
other vector drawings.


See Also

Zoom
Options - Display Options

/ONE - View->Vector Colors.../ Point Colors...
View Vector Colors...
View Point Colors...

Purpose 

To adjust the color that vector or point GIS layers are
rendered in.

Usage 

The color that each vector GIS layer is displayed in
is coded in the vector GIS layer header file. While
this value can (but probably should not) be edited by
the user, the vector colors are more readily adjusted
by using this Unit Hydrograph feature.

Simply select the GIS layer for which you wish 
modify the color. Then select among the list of colors
that were specified in the configuration file. A small
window previews the color.

This is not a permanent change. The next time you
enter Unit Hydrograph, the original vector colors will
be invoked. Hopefully we've selected reasonable colors
for the various vector GIS layers. If not, contact us
for guidance on making permanent changes to the color
values assigned in the header files.

Hints

Make sure the gis layer colors contrast well with
the background color. It is possible to make a layer
"invisible" by assigning it the same color mix as the
background color. Likewise, select the vector colors to
contrast well with the raster layers you plan to display.
The color tables assigned to raster files can not be
modified by the user.
 
See Also


/ONE - Zoom
Zoom

Purpose

To control the limits of the display region.

Usage 

Select an item from the Zoom cascading menu to define
the geographic limits of the portion of the RFC 
displayed in the Unit Hydrograph viewing window. The
Zoom menu items allow you to zoom in to and out from
the RFC in addition to allowing you to redefine the
center of your view of the RFC.

Relationships

The items on the Zoom menu allow you to control how
much data is visible in the Unit Hydrograph viewing
window. What data is actually displayed is selected
in the View - Features dialog.

Hints

See that dotted line at the top of Zoom's pull down
menu? If you click on it the Zoom menu is torn away
from the Unit Hydrograph menu bar. This is a handy
feature if you plan to zoom and pan several times
during an Unit Hydrograph session.

See Also

View - Features
Unit Hydrograph Interface

/ONE - Zoom->Zoom to Box
Zoom - Zoom to Box

Purpose 

To select a smaller display region by defining a
"rubber band" box around a smaller area. 

Usage

This feature allows the user to "tighten" the view
of the RFC by defining a "rubber band" box around a
smaller area of interest. The cursor will change
shape from a pointer to a cross hair. Position the
cross hair on the first corner of the smaller region
and depress the left mouse button.  Then position the
cross hair on the second corner and depress the left
mouse button again. Between the first and second 
mouse button depressions a "rubber band" box will be 
displayed indicating the limits of your new view. 
Upon selection of the second box corner the "rubber 
band" box will be erased, the cursor will revert back
to a pointer, and your new view will be rendered. 
There is no need to keep the left mouse button 
depressed between the first and second zoom box 
corner selections. The order in which box corners are
selected is not important.

You will note that Unit Hydrograph will make every
attempt to fill the display canvas up to its edges.
Because of this feature, the zoomed image will almost
always be larger along one of its axis than the area
described by the zoom box. The displayed area will
however include all of the data requested by the user.

Relationships

If you change your mind while in the process of 
defining your zoom box you can simply make a new
selection from the Unit Hydrograph menu. The
"rubber band" box will disappear, the cursor will
revert back to a pointer, and your current view
will remain the same.

Hints

Some of the GIS layers take longer to display than
others. You may find it useful to wait until you've
tightened your view before displaying time consuming
GIS layers.  Also, raster GIS layer color table
scaling is a feature you may wish to use with
discretion if image rendering times are unacceptable.

Errors

There is a known bug in the display system when you
zoom in too tightly. The vector layers have a
tendency get confused when you zoom in on an area
smaller than a pixel.

See Also

Options - Display Options
View - Features
Zoom - Zoom In On Basin From List
Zoom - Zoom In On Center
Unit Hydrograph Interface

/ONE - Zoom->Zoom to Basin...
Zoom - Zoom to Basin...

Purpose 

To select a smaller display region by selecting a
basin to zoom in on from the basin name list box. 

Usage

This feature allows the user to "tighten" the view
of the RFC by selecting a basin from a list of basins
in the currently open basin layer.  The view will be 
adjusted to the limits of the selected basin plus a 
modest buffer. The size of the buffer is defined in 
the Unit Hydrograph configuration file. 

Relationships

The basin list box is used by several Unit Hydrograph
features requiring basin selection by name. Upon
selection of Zoom to Basin, or any other
feature requiring the selection of a basin by name, a
list box dialog will be displayed if not already
displayed. The list box dialog will remain displayed
and will be managed throughout the entire Unit
Hydrograph session unless dismissed by the user. All
Unit Hydrograph features requiring selection of a
basin by name will share this list box dialog.

Hints

Some of the GIS layers take longer to display than
others. You may find it useful to wait until you've
tightened your view before displaying time consuming
GIS layers.  Also, raster GIS layer color table
scaling is a feature you may wish to use with
discretion if image rendering times are unacceptable.

See Also

Options - Display Options
View - Features
Zoom - Zoom to Box
Zoom - Zoom In at Center
Unit Hydrograph Interface

/ONE - Zoom->Zoom to Extents
Zoom - Zoom to Extents

Purpose 

To select a larger display region by resizing the 
display region to the maximum limits (set in the 
config file). 

Usage

This feature allows the user to "expand" the view
of the RFC by resizing the viewing area to the 
limits defined in the Unit Hydrograph config file.


Hints

Some of the GIS layers take longer to display than
others. You may find it useful to unselect time
consuming GIS layers before expanding your view.
Also, raster GIS layer color table scaling is a 
feature you may wish to use with discretion if image
rendering times are unacceptable. 

See Also

Options - Display Options
View - Features
Zoom - Zoom Out at Center
Configuration File


/ONE - Zoom->Zoom In on Cursor
Zoom - Zoom In on Cursor

Purpose 

To select a new display region and zoom in by
shifting the display region center point and zooming
in on such point. 

Usage

This feature allows the user to redefine the center
of the RFC view as well as zoom into the picture.
The cursor will change shape from a pointer to a
crosshair. Position the crosshair on the center of
your new view and depress the left mouse button. 
Upon selection of the new view center the cursor 
will revert back to a pointer and your new view 
will be rendered.

Relationships

The current image center defines the center for rapid
zooming in and zooming out from the view center.

If you change your mind while in the process of 
defining your new view center you can simply make a
new selection from the Unit Hydrograph menu. The
cursor will revert back to a pointer and your
current view will remain the same.

See Also

Zoom - Zoom In at Center
Zoom - Zoom Out at Center
Zoom - Zoom Out on Cursor
Unit Hydrograph Interface

/ONE - Zoom->Zoom Out on Cursor
Zoom - Zoom Out on Cursor

Purpose 

To select a new display region and zoom out by
shifting the display region center point and zooming
in on such point. 

Usage

This feature allows the user to redefine the center
of the RFC view as well as zoom out from the picture.
The cursor will change shape from a pointer to a
crosshair. Position the crosshair on the center of
your new view and depress the left mouse button. 
Upon selection of the new view center the cursor 
will revert back to a pointer and your new view 
will be rendered.

Relationships

The current image center defines the center for rapid
zooming in and zooming out from the view center.

If you change your mind while in the process of 
defining your new view center you can simply make a
new selection from the Unit Hydrograph menu. The
cursor will revert back to a pointer and your
current view will remain the same.

See Also

Zoom - Zoom In at Center
Zoom - Zoom Out at Center
Zoom - Zoom In on Cursor
Unit Hydrograph Interface


/ONE - Zoom->Pan To Cursor
Zoom - Pan To Cursor

Purpose 

To select a new display region by shifting the  
display region center point. 

Usage

This feature allows the user to redefine the center
of the RFC view. The cursor will change shape from a 
pointer to a cross hair. Position the cross hair on 
the center of your new view and depress the left 
mouse button.  Upon selection of the new view center 
the cursor will revert back to a pointer and your new
view will be rendered.

Relationships

The current image center defines the center for rapid
zooming in and zooming out from the view center.

If you change your mind while in the process of 
defining your new view center you can simply make a
new selection from the Unit Hydrograph menu. The
cursor will revert back to a pointer and your
current view will remain the same.

See Also

Zoom - Zoom In at Center
Zoom - Zoom Out at Center
Zoom - Zoom In on Cursor
Zoom - Zoom Out on Cursor
Unit Hydrograph Interface

/ONE - Zoom->Zoom In at Center
Zoom - Zoom In at Center

Purpose 

To select a smaller display region by zooming in on
the display region center point. 

Usage

This feature allows the user to "tighten" the view
of the RFC by decreasing the limits of the view about
the center of the current view. The degree of zooming
is controlled by the current zoom setting.

Relationships

The degree to which zooming in on displayed features 
occurs with each selection of this menu item is 
controlled by Zoom - Set Zoom Factor. 

Hints

Some of the GIS layers take longer to display than
others. You may find it useful to wait until you've
tightened your view before displaying time consuming
GIS layers. Also, raster GIS layer color table
scaling is a feature you may wish to use with
discretion if image rendering times are unacceptable.

Errors

There is a known bug in the display system when you
zoom in too tightly. The vector layers have a
tendency get confused when you zoom in on an area
smaller than a pixel.

See Also

Options - Display Options
View - Features
Zoom - Zoom to Box
Zoom - Zoom to Basin...
Zoom - Zoom Out at Center
Zoom - Zoom In on Cursor
Zoom - Zoom Out on Cursor
Zoom - Pan To Cursor
Zoom - Set Zoom Factor

/ONE - Zoom->Zoom Out at Center
Zoom - Zoom Out at Center

Purpose 

To select a larger display region by zooming out from
the display region center point. 

Usage

This feature allows the user to "expand" the view
of the RFC by increasing the limits of the view about
the center of the current view. The degree of zooming
is controlled by the current zoom setting.

Relationships

The degree to which zooming out from displayed 
features occurs with each selection of this menu item
is controlled by Zoom - Set Zoom Factor. 

Hints

Some of the GIS layers take longer to display than
others. You may find it useful to unselect time
consuming GIS layers before expanding your view.
Also, raster GIS layer color table scaling is a 
feature you may wish to use with discretion if image
rendering times are unacceptable. 

See Also

Options - Display Options
View - Features
Zoom - Zoom to extents
Zoom - Zoom In at Center
Zoom - Pan To Cursor
Zoom - Zoom In on Cursor
Zoom - Zoom Out on Cursor
Zoom - Set Zoom Factor

/ONE - Zoom->Set Zoom Factor
Zoom - Set Zoom Factor

Purpose 

To control the degree to which the display region is
zoomed in on or out from.

Usage

This feature controls the degree of zooming in and
zooming out from center. The user slides the slider
left or right to the desired zoom level. The reported
number is not the degree of magnification or 
reduction. Rather, it is the the degree to which
each axis of the image will be scaled up or down.

The initial or default zoom setting is defined in the
Unit Hydrograph configuration file.

Relationships

Altering the zoom setting controls the degree to 
which the displayed features are zoomed in on or
zoomed out from with each selection of Zoom - Zoom In
at Center and Zoom - Zoom Out at Center.

See Also

Zoom - Zoom In at Center
Zoom - Zoom Out at Center
Configuration File

/ONE - Help->Help
Help - Help 

Purpose

On-line Unit Hydrograph user documentation.

Usage

Select a help item from the list box at the bottom of
the Help dialog. The help items are grouped by the
alphabetized Unit Hydrograph menu bar items.
Additionally, we've included help information on the
Unit Hydrograph Interface, frequently asked questions,
a glossary, and the Unit Hydrograph configuration file.
When a help item is selected, the help information on
the selected topic is displayed in the text box at the
top of the help dialog.
 
Hints

The contents of the file displayed by the Unit
Hydrograph help system may be edited by the user. The
file is named uhg.hlp. New help sections may be added
by enclosing the new section headings in arrow braces.
The text following the arrow brace enclosed headings
is displayed as help text. You can augment this help
file by adding text to existing help sections and by
creating new help sections.

Help file lines preceded by double forward slashes
are ignored by the Unit Hydrograph help system. The
double slashes indicate help file comment lines.

See Also

Help - Help Espanol
Help - About Unit Hydrograph 

/ONE Help - Help Espanol
Help - Help Espanol

Purpose

(Optional) On-line Unit Hydrograph user documentation
in Spanish

Usage

This works exactly the same as the English help file.
Unit Hydrograph will look for an "uhg.hlp.e" file or a
spanish help file specified in the configuration file.
If none are found, this menu item will be grayed out.

Hints

See Also

Help - Help
Help - About Unit Hydrograph

/ONE - Help->About Unit Hydrograph
Help - About Unit Hydrograph

Purpose 

Reports the Unit Hydrograph version number and details
on how to contact the Unit Hydrograph developers for
information about Unit Hydrograph not covered in the
Unit Hydrograph help system. The date and time of the
last compilation are displayed on the Unit Hydrograph
status line.

See Also

Help - Help
Help - Help Espanol

/ONE Map Display
Map Display

The main body of the Unit Hydrograph interface is
devoted to displaying map features. There are two
parts to the map display. The major part, on the
right, is used to display raster images and vector
drawings. Only one raster image can be displayed at
any time. As many vector drawings as you like may
be displayed on top of a raster image or by
themselves. Several Unit Hydrograph features are 
devoted to control what and how much map data is
displayed.

The minor part, on the right, contains the legend for
the data currently displayed. Since the legend can
be quite large yet is not scaled, it often does not
fit into the space provided. Scroll bars on the left
and bottom edge of the legend can be used to make
any portion of the legend visible. It's worth noting
that the size of the legend is a proportion of the
main window's size. Resizing the Unit Hydrograph
main window makes the legend wider and taller.

Coordinate Display

On the four corners of the map display we print the
geographic limits of the current viewing area. In the
lower right-hand corner of the Unit Hydrograph main
window we display the current cursor position. The
format of coordinate display is a user selectable
option - see Query or View Options. 

Coordinates are always displayed relative to the 
northwest hemisphere. In other words, degrees West
followed by degrees North. Coordinates are always
displayed in geodetic (longitude/latitude)
coordinates on the World Geodetic System 1984
horizontal datum.

Coordinate Entry

When Unit Hydrograph expects coordinate entry
remember that it wants geodetic coordinates relative
to the World Geodetic System 1984 horizontal datum. 
Coordinates are always assumed to be in the northwest
hemisphere. Regardless of the sign of your 
coordinate input, Unit Hydrograph assumes you mean the 
northwest hemisphere. Therefore:

   95.0 lon  45.0 lat converts to -95.0 lon 45.0 lat
  -95.0 lon -45.0 lat converts to -95.0 lon 45.0 lat
  -95.0 lon  45.0 lat converts to -95.0 lon 45.0 lat
   95.0 lon -45.0 lat converts to -95.0 lon 45.0 lat

Also, Unit Hydrograph does not want to see E, W, N, S,
etc. in the coordinate entry.

Arrow Keys

The cursor can be moved by the mouse or by the arrow
keys. The mouse is fast; the arrow keys are precise.
The space bar acts as the left mouse button and the
Enter key as the right mouse button.

What's Going On ? or
What's a Person To Do ?

To the left of the cursor position display box we've
placed an Unit Hydrograph status box. The box reports
what should be done next in the Unit Hydrograph dialog
that has current focus. In the event that Unit
Hydrograph is in the middle of processing data, the
status box will report the what its working on. In the
event of an error the status box, in addition to an
error pop-up dialog, will report the nature of the
error. 

Cursors

Cursors of different shape are used to give the user
an additional indication of the state or the action
about to be performed.
  Normal arrow is the default cursor for the 
      majority of the time.
  Watch cursor signifies that the computer is
      busy and is not responding at this time.
  Box Kite denotes that the viewer will zoom to
      the area delimited by the points the user
      clicks on.
  Cross is used to select an area, or a point
      in the query mode. 

Selecting Basins

You'll usually select a basin from a map display. But
some folks like to select basins by name. The basin 
name dialog is shared by all Unit Hydrograph features 
requiring you to select a basin name from a list of 
basin names.

The first time a basin name is to be selected from a
list, the list is displayed in a dialog. The dialog
will remain displayed throughout the Unit Hydrograph
session or until dismissed by the user. If another
basin list Unit Hydrograph feature is selected and
the list is already displayed, simply select the basin
from the existing basin list. The basin list is
maintained throughout the Unit Hydrograph session.


/ONE Frequently Asked Questions
Frequently Asked Questions

                      ( NONE )

/ONE Glossary
Glossary

CWA    : County Warning Area
D8     : A means of representing flow directions in
         a raster format. For a given elevation pixel
         the eight neighbors are examined. The pixel
         with the lowest elevation relative to the
         center pixel defines the flow direction.
         There are eight possible flow directions:
         north, northeast, east, southeast, south,
         southwest, west, and northwest.
dangling stream :
         A stream whose tail water does not tie into
         another stream.
DEM    : Digital Elevation Model. A raster data file
         containing terrain elevations. Our DEM was
         constructed from 3-arc second USGS DEM's and
         Canadian DTED files.
DLG    : The USGS Digital Line Graph format for
         vector data sets.
EPA    : The Environment Protection Agency
flow accumulation :
         The sum total area of all terrain flowing
         to a given pixel not including the area of
         that pixel.
flow direction :
         The D8 direction that water from a given
         pixel flows. See D8.
focus  : The Motif window that is currently receiving
         keyboard or mouse input.
GIS    : Geographic Information System. Software for
         managing geographically distributed data.
HSA    : Hydrologic Service Area
NOHRSC : The National Operational Hydrologic Remote
         Sensing Center
non-contributing-area :
NCA    : Part of the landscape into which water flow
         but out of which water does not flow.
NWS    : The National Weather Service
parent basin :
         The basin in which a rain-on-reservoir
         resides.
pixel  : Picture element. An individual raster matrix
         value. A pixel defines a value at a specific
         raster location.
rain-on-reservoir basin :
ROR    : A basin whose spatial limits are defined
         by the maximum pool elevation of a dammed
         reservoir. An ROR basin is an island polygon
         within a parent basin polygon.
raster : A matrix of digital values which, when
         displayed, forms a continuous tone image.
RF1    : Reach File version 1. USGS DLG rivers and
         streams data set modified by the EPA to
         accurately characterize the nation's
         hydrography. Our RF1 was modified to
         correctly represent hydrographic topology
         and to register with the DEM.
RFC    : River Forecast Center
topology :
         The order in which objects are linked
         together.
USGS   : The United States Geological Survey
vector : An array of values which, when displayed,
         forms a map image of points, lines, and
         areas.

/ONE Configuration File
Configuration File

Changes made to the configuration file take effect
only upon reentering Unit Hydrograph Application. 

'nohrsc.cfg' has the following entries pertaining to 
Unit Hydrograph:

      ** Program Layers And Parameters **


DATABASE      = Informix database name 
                (main database for attributes)
                Required - e.g. 'gisrs'
DATAPATH      = Saved hydrograph file location
		default is the uhg application directory
RADIX  	      = Initial Unit Hydrograph display degrees
                format. 
                options: 10 for decimal degrees
                         60 for DDDMMSS.S
                Optional - default is 10
UHGHELP       = this help file 
                Optional - default is 'uhg.hlp'
SPANISHUHGHELP= help file in spanish (where necessary)
		Optional - default is 'uhg.hlp.e'.
RESCALE       = Initial Unit Hydrograph optional parameter
                rescale on zoom. Yes or No
                Optional - default is Yes
LEGEND        = side of screen that GIS legend appears on.
                LEFT or RIGHT. Optional - default is HIDE. 
                (not viewed)
RFC           = RFC name
                (for extents and zoom limits)
                Required - e.g. ABRFC
STARTHEIGHT   = Initial UHG GIS display window
                fraction of monitor height (.1-.99)
                Optional - default is .70
STARTWIDTH    = Initial UHG GIS display window width
                fraction of monitor width (.1-.99)
                Optional - default is .70
UHGHEIGHT     = Initial UHG hydrograph window height
                fraction of monitor width (.1-.99)
                Optional - default is .30
UHGWIDTH      = Initial UHG hydrograph window width
                fraction of monitor width (.1-.99)
                Optional - default is .40
UNITS         = Initial Unit Hydrograph display and export
                units. options: English or Metric
                Optional - default is English
ZOOMFACTOR    = Startup zoom in/out factor. 
                Optional - default is 2.0
BGCOLOR       = Startup background color, also
                used as the color for older hydrographs.
                Optional - default is system color.
HICOLOR       = Startup highlight color, used for drawing
                hydrographs. 
		Optional - default is white (256 256 256).
MAXY	      = Zooming out extents of RFC - North. Required.
MAXX          = Zooming out extents of RFC - East. Required.
MINY          = Zooming out extents of RFC - South. Required.
MINX          = Zooming out extents of RFC - West. Required.

      ** Raster Layer Names **
ACCUMULATION  = flow accumulation raster layer
                (for computation and display)
                Required - 
ASPECT        = aspects raster layer
                (for display only)
                Required - e.g. abdem_15.a
ELEVATION     = DEM raster layer
                (for display only)
                Required - e.g. abdem_15.e
FLOWDIRECTION = flow direction raster layer
                (for computation and display)
                Required - 
SLOPE         = slopes raster layer 
                (for display only)
                Required - e.g. abdem_15.s

      ** Vector Layer Names ** 
COUNTIES      = counties boundaries vector layer
                (for display only)
                Optional - e.g. counties 
CWAS          = county warning areas vector layer
                (for display and selection)
                Required - e.g. cwas
HUCS          = HUCS vector layer
                (for display only)
                Optional - e.g. hucs
LAKES         = lakes and streams vector layer
                (for display only)
                Optional - e.g. lakes
RFCS          = RFC boundaries vector layer
                (for selection and display)
                Required - e.g. rfcs
RIVERS        = major rivers vector layer
                (for display only)
                Optional - e.g. rf1_150
STATES        = states boundaries vector layer
                (for display only)
                Optional - e.g. states
WORLD         = world outline vector layer
                (for display only)
                Optional - e.g. world
STATIONS      = Observation station point layer
                (for display only)
                Optional - e.g. stations
BASINS        = default opened basin layer
		(for computation, selection, etc.)
		Optional, a default which opens
		upon starting Unit Hydrograph.
REFBASINS     = reference basins vector layer
                (for display only)
                Optional - e.g. basin_1995

     ** Hydrograph Creation Variables **
     
UHGCONSTANTVELOCITY	- Constant flow velocity
UHGLANDCHANNELK		- Landcover-based K-factor
UHGFLOWOVERLANDK	- Overland flow K-factor
UHGFLOWSWALEK		- Swale flow K-factor
UHGFLOWCHANNELK		- Channel flow K-factor
UHGACCUCHANNELK		- Accumulation flow K-factor
UHGMEANVELOCITY		- Accumulation mean velocity
UHGOVERLAND	 	- Overland distance value
UHGKFACFORESTED         - Velocity K-factor for Forest
                          with heavy ground litter,
                          hay meadow (overland flow)
UHGKFACFALLOW	        - Velocity K-factor for trash
                          fallow or minimum tillage
                          cultivation; countour or strip
                          cropped; woodland (overland flow)
UHGKFACPASTURE		- Velocity K-factor for short
                          grass pasture (overland flow)
UHGKFACCULTIVATED       - Velocity K-factor for cultivated
                          straight row (overland flow)
UHGKFACUNTILLED		- Velocity K-factor for nearly 
                          base and untilled (overland flow)
                          Alluvial fans in mountain regions
UHGKFACGRASSED		- Velocity K-factor for grassy
                          waterway
UHGKFACPAVED		- Velocity K-factor for paved area
                          (sheet flow); Small upland
                          gullies
     
UHGDURATION		- Duration of hydrograph

SCSCOEFFICIENT		- Coefficient for SCS equation
SCSCURVENUMBER		- Curve number for SCS equation

UHGRFACTOR		- R-factor for non-SCS equations
FDMSEGMENTS		- # of FDM segments per cell
FDMTIMEINTERVAL		- Time interval for FDM equation
	
             
Only lines starting with these keywords are 
processed.  All other lines are considered comments.

/ONE Unit Hydrograph Version History
Unit Hydrograph Version History

Version 1.10
------------
Date    : Nov. 1998 - Dec. 1998
Features: 
        * First non-beta release
        * Background and hydrograph colors can now be modified.

Version 1.11
------------
Date    : Dec. 1998
Features: 
        * Basin Outlets layer now viewable.
        * Able to change colors of point data.
        * English/Spanish help file system simplified.

Version 1.12
------------
Date    : Jan. 1999
Features:
        * Fixed a bug with querying ROR basins
        * As with nohrsc, can now execute outside 
          <BIN> directory.
        * Can also use local configuration files
          if executed outside the <BIN> directory.

Version 1.13
------------
Date    : Jan. 1999
Features: 
        * Fixed some minor bugs.
        * Added Recalculate to the Edit submenu.
          (Older hydrographs can be updated if the 
          basin geometry changes.)
          
Version 1.15
------------
Date    : June 1999
Features:
        * Miscellaneous GUI tweaks involving fonts.
        * Support for expanded basin attributes :
              Elevation Zone boundaries
              Mean/Minimum/Maximum slope, elevaton, & aspect
        * Opening the old format basins in IHABBS will
          update the basin attributes. This will occur 
          without the need of saving the basin layers.
        * Query basin now has an option for "Less" or
          "More", where the user may view the traditional
          basin attributes, or the expanded version which
          includes the fields described above.
          Exported hydrograph preview is stepped. 

Version 1.16
------------
Date:   : Aug. 1999
Features:
        * Select from list dialog bug fixed.
        
Version 1.17
------------
Date    : Nov. 1999
Features:
        * Exported hydrograph's number of ordinates field
          corrected.

Version 1.18
------------
Date    : Dec. 1999
Features:
        * Fixed widget parent bug.
        * Allows selection of rain-on-reservoir basins
        * Allows selection of basins that contain
          rain-on-reservoir basins.
        * Checks to see if hydrograph is saved properly.

Version 1.20
-------------
Date    : May 2000
Features:
        * Added ability to display land use and cover

Version 1.21
------------
Date    : July 2000
Features:
        * Added progress messages to unit hydrograph creation
        * FDM method stops after routing within 1 cu. mm.
          Effectively halves processing time

Version 1.22
------------
Date    : May 2001
Features:
        * Error messages while saving unit hydrograph
          more verbose
        * Allows RFC name to be up to 64 characters long
          (from 5)
        * Initializes "AutoClear" display option properly
        * Sets working directory properly
          (current directory)
        * Fixed exposed canvas callback which allows
          non HP X library displays to successfully 
          select with mouse

Version 1.23
------------
Date    : Feb. 2002
Features:

        * linux version
        * Support for read only/24 bit color
        * More tolerant startup

Version 1.24
------------
Date    : Mar. 2002
Features:

        * Changing vector/point color interface
          issues fixed

Version 1.25
------------
Date    : June 2004
Features:

        * Rescale on Zoom checks appropriate raster area
        * Fixed potential crash bug when closing layer
        * Minor spacing fixes in View Hydrograph and View
          Features dialogs

Version 1.26
------------
Date    : April 2005
Features:
        * Checks presence of river layer before calling
          generation methods
        * Does not needlessly alter hydrograph table
        * More thorough checking of i/o failures

Version 1.27
------------
Date    : October 2007
Features:
        * Compatible with PostgreSQL
        * Looks for SCHEMA in config file
        * Fixed exported end-of-lines
        * Tests hydrograph attribute table presence
        * More careful saving of files

Version 1.28
------------
Date    : June 2009
Features:
        * Corrected handling of one-digit header  values in 
          saved hydrographs
        
// 
// End of uhg.hlp //
//
