×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# HEC-HMS flood basin Modeling as per CWC Subzone SUH method

## HEC-HMS flood basin Modeling as per CWC Subzone SUH method

(OP)
Hi there, I am Hydrologic Engineer from India,

I am new to HEC-HMS i request help. Here in one of our project, we have to calculate design discharge (50 / 100 year return period floods) for many bridges. Central Water Commission of India has divided the country into various meteorological sub zones and published synthetic unit hydrograph parameters, 50, 100 Year rainfall maps and guidelines (including base flow & loss rate and temporal distribution co-effcients%) to calculate flood upto 5000 sq km catchment area. Though we have excel calculation sheets, As we have more no of catchments to do, we decided to adopt HEC-HMS with SCS-Unit Hydrograph method transform method. My issue is
1) with manual(Excel) method we use duration of storm (Td) = time to peak (UH) X 1.1 (suggested in guidelines) with the total depth of storm obtained from the map. In Frequency storm method of HEC-HMS has storm duration options of 3Hr, 6hr, 12hr, 24hr upto 4 days fixed. How can i use it if duration of storm calculated is not of any available options in HMS? Moreover peak intensity position option available in HMS are 25%, 33%, 50%, 67% & 90%. What if my manually calculated value is falling in-between these % values. I tried with nearby options and getting peak flow having difference of more than 25% compared to manually (excel) calculated methods. How to adopt this method efficiently to get results within 5 to 10% difference to manual method(excel)?

2) If i use gauge weight method rainfall in HMS using rainfall provided directly calculated using co-efficients, if the duration of storm is less than base width of UH and if we arrange the hourly increments to match with UG peak ordinates vise versa, should we fill initial hours until start of actual rainfall as zero rainfall? I am getting large% (>25%) of difference in flood peak (Manual VS HMS) in this method too. Kindly help.

I attached the model with this.
Regards

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!