This command has a collection of tools to analyze the runoff of a
surface defined by triangulation. After selecting the triangulation
file of the surface, the program docks a dialog on the left side of the
drawing window. While the Watershed Analysis dialog is running, other
AutoCAD and Carlson commands are not available. To zoom or pan the
drawing view, use the buttons at the top of the dialog, or use the
middle button of a wheel-mouse.
The Process button
calculates the flow connections between the triangles and along the
edges of the triangulation. Most of the Watershed Analysis functions
make use of these flow connections. So running Process is typically the
first step. The Rainfall
amount is used in the Process function for figuring the runoff volume
to determine when the volume is enough to spillover a local depression
in the surface. Besides the Rainfall amount, the runoff coefficients as
defined in Define Runoff Layers are also used to calculate the runoff
volumes. When the local depression is small enough the srunoff will
continue through. Otherwise this spot is called a sink for where the
runoff stops.
The Draw Watersheds
function draws the watershed areas using the settings under the Options
tab. The back arrow next to the Draw Watersheds button will erase any
previous Draw Watershed entities. The Fill
Watershed Areas option will solid fill hatch each area using
different colors. The Draw Sink
Locations setting draws a symbol at the low point for each
drainage area. The Draw Pond Areas
option draws a solid fill hatch in blue for the area covered by the
runoff volume of low points. In the example shown, the Fill Watershed
Areas and Draw Sink Locations options are active. The Draw Max Flow Lines option draws
polylines for the longest flow line within each watershed. These
longest flow polylines can be used to calculate the time of
concentration.
The Draw Pond Areas button
draws solid fill hatch in blue for the areas covered by the runoff
volume of low points. This is the same function as the Draw Pond Areas
option within Draw Watersheds routine.
The Watershed Above Point
function reports the watershed data of the current pointer position in
real-time as the pointer is moved around. The watershed data is shown
in a tooltip next to the pointer position. This data has values for the
overall watershed that the position is in including the sink elevation,
sink name, drainage area and average slope percent. This data also has
values for the watershed above the current point including the drainage
area and runoff volume. Plus this data shows the elevation and runoff
coefficient at the current point. If the position is picked with the
mouse, then the program draws a polyline perimeter for the drainage
area above the current point.
The Runoff Tracking
function draws flow lines that follow the surface. The Single Point Tracking method draws
the flow lines starting from the picked high points. The Whole Surface Tracking method draws
a flow line starting from the middle of each triangle in the
triangulation. The Major Flow Tracking
method draws starting in triangles where the drainage area coming into
triangle exceeds the specified Cutoff
Area Above value. The flow lines can be drawn as either 2D or 3D
polylines. For 2D polylines, the linetype can be specified or the
special linetype with flow direction arrows can be used. This special
flow linetype has controls for the size and frequency of the flow
arrows.
The Draw Connections
function draws lines with arrows between the triangles for how the
program has determined their flow connections.
When a triangulation file is processed by Watershed Analysis, some
of the flow connection data is stored into the triangulation file to
speed up reprocessing. The Reprocess
Topo function resets this flow connection data to start the flow
calculations from scratch.
The Detail Inspector
function reports flow connection data at the pointer position in
real-time as the pointer is moved. This data includes the current
position triangle number, connecting flow triangle number, sink node
number, watershed name, border elevation, ridge elevation, low
elevation, downstream sink number, number of source triagnles, number
of source nodes, current elevation and spillover elevation.
The Inspect function
reports runoff flow data at the pointer position in real-time as the
pointer is moved. The runoff data is shown in a tooltip next to the
pointer and in the Data tab.
This data has values for the overall watershed that the position is in
including the sink elevation, sink name, drainage area and average
slope percent. This data also has values for the watershed above the
current point
including the drainage area and runoff volume. Plus this data shows the
elevation and runoff coefficient at the current point. When the Hatch
Area Being Inspected option is active, the watershed area for the
current position is hatched during inspection.
The Watershed Report
function runs the report formatter to choose which of the watershed
parameters to report. The Pond Report
function reports the position and depth of each ponding area.
Besides calculating the runoff of the triangulation surface,
Watershed Analysis can also process the runoff effects from structures
for inlets, storage ponds, culverts and channels. The structures in
Watershed Analysis are simply for placement and watershed delineation.
These structures do not have design considerations for parameters like
pipe size. In the Structure
tab, there is a list of the structures to apply with the current
surface. The list shows the name, type and drainage area for each
structure. The Draw function will draw symbols for each structure. The
Inlet structures act as sinks in the watershed and capture all the flow
that comes to the inlet point. Each inlet is defined by a single point
and a name. The Storage Tank structures also act as sinks and are
defined by a single point and name. The Culvert structures route the
flow from the culvert inlet to the outlet. The culverts are defined by
two points for the inlet and outlet and by a name. The Channel
structure is the same as the Culvert except that it can have more than
two points to define the flow path. The structure data can be stored to
a Watershed Structure File (wst) using the Save button. The Load button can read the structure
data from either a wst file or from a sewer network file (.sew).
Pulldown Menu Location:
Watershed
Keyboard Command: watershed
Prerequisite: Triangulation File
File Name: \lsp\cntr_grd.arx