Brief presentation to assist the reviewer of a HydroCAD model to ensure it meets requirements. HydroCAD contains node reports, calculation settings, and automatic input warning messages that can be easily checked.

1. Aspects of HydroCAD Models For
Review
Chris Chatfield, P.E.
Based on HydroCAD Software Solutions, LLC Webinar

2. Overview
Here are the following areas of HydroCAD that may be reviewed to ensure the model
matches desired hydrologic criteria:
1. Subcatchment Node Report
2. Calculation Settings
3. Reach Node Report
4. Automatic Input Warning Messages
5. Link Node Report
6. Pond Node Report
It is important to note that specification of HydroCAD as the ‘method of water
resource calculation’ is not a sufficient explanation due to the variety of methods.

3. Subcatchment Node Report
Subcatchment Node
Purpose
● models the effect of rainfall on part of the
watershed and produces a runoff hydrograph
Typical Use ● drainage area
User Inputs
● area, curve number (value not from table will
have an asterix)and time of concentration
Calculated Outputs
● flow, volume, depth, and velocity/capacity of
time of concentration segments

4. Calculation Settings - General Tab
Reach Routing Method
Storage Indication
Storage Indication + Translation
Dynamic Storage Indication
Simultaneous
Muskingum Cunge
● the time step should be
less than ⅕ of time of
concentration
Dynamic Muskingum Cunge
● may respond to tailwater
effects
Pond Routing Method
Storage Indication
● stage storage with
stage discharge
Dynamic Storage Ind.
● compensates for
changing tailwater
Simultaneous
● reevaluates discharge
at each time step
Runoff Method
SCS Unit Hydrograph
Santa Barbara Urban Hydrograph
● similar to SCS
● may need to separate
impervious and pervious
calculations
Rational
● not used for detention pond
design or analysis
Note: Reach and pond routing methods must be compatible

5. Rainfall Options Tab
● Rainfall Event
○ frequency of storm
● Storm Type
○ over 30 types, ex. Type II 24 hr
● Storm Curve
○ curve within a specific storm type,
ex. Type 1 of RSA 24hr storm type
● Storm Duration & Depth
● AMC
○ moisture level in ground before
storm, default is 2
Unit Hydro Tab
● Unit Hydrograph
○ SCS & over 15 others

6. Reach Node Report
Reach Node Purpose
● shows effect of a hydrograph being routed
through a uniform stream
Typical Use
● open channel ditch or partially full pipe
● full pipe is a pond with a culvert outflow
User Inputs ● n value, length, slope, and invert/outlet
Calculated Outputs ● inflow/outflow, velocity, and peak storage

7. Automatic Output
Warning Messages
● HydroCAD automatically Checks Inputs
For Errors After Calculations
● Red warnings must be addressed
● Yellow warnings are suggestions
● Examples of Errors
○ exceeded node capacity
○ longer time span for calculation advised
○ node had no inflow
○ dam breach started at x.xx hrs.
○ culvert outlet resized to xx”
○ non default antecedent moisture content
○ tailwater condition issue
■ change pond routing method
○ pipe Is Detaining Water
■ should be modeled as a pond

8. Link Node Report
Link Node Purpose
● enters a hydrograph generated outside
HydroCAD or to connect routing diagrams
Types
● internal, manual, and file link (read ASCII
export of another HydroCAD model)
User Inputs
● hydrograph, water surface elevation, and flow
threshold
Calculated Outputs ● none, reports only displays inputs

9. Pond Node Report
Pond Node Purpose
● models the storage effects of any retention or
detention area
Typical Use
● detention areas as well as catch basins or
others that create headwater on an outlet
User Inputs
● inflow/outflow method, routing method, flood
elevation, stage/storage table, and outlet device
Calculated Outputs
● detention time, peak elevation, peak storage,
outlet device max flow, and headwater

10. Sources
In-production ervice
Urban Water Engineering and Management By Karamouz, Etc.
https://www.youtube.com/watch?v=2icA6IKHQrI
HydroCAD 10.00-20 Sampler (20 node s/n S24998)
Advanced projects