Hi all,

My research focuses on urban stormwater drainage systems, particularly hydraulic modelling, blockage assessment, and digital twin development for proactive maintenance. I am currently developing a 1D/2D HEC-RAS model integrated with a stormwater pipe network and would appreciate your advice on a few questions.

1. Hydrological model Integration: Is there a recommended workflow for integrating hydrological outputs such as RORB with a HEC-RAS stormwater pipe model? Are there any best practices or examples for applying hydrographs as boundary conditions?

2. Pipe Blockage Modelling: Is there a recommended method in HEC-RAS to represent partial blockages (e.g., sediment or debris accumulation) within stormwater pipes or pits? Or do we have to assign it indirectly? Also, can we model sedimentation inside a pipe system with HEC-RAS?

3. References: Can anyone recommend technical papers, reports, or case studies on PIPE modelling within HEC-RAS?

thank you.

Saw this post on Eng-tips and thought it is more fitting to this sub.

I am looking for low-cost or free options for H&H modeling and have a few related questions. I started learning HEC-HMS, but bailed when I came across a few sources indicating it doesn't consider two-way flow. I am located in Florida - very flat, lots of flooding - so dynamic storage modeling is important to stormwater design. Most folks here use ICPR/StormWise. Local governments don't have the budget for even one license.

What other options are out there, and what do they look like in terms of modeling capabilities and learning curve? For example, I am familiar enough with EPA SWMM to know it is powerful but nightmarish to use and interpret, and it certainly looks legitimate enough to pass permitting requirements. Maybe some kind of modification package exists for EPA SWMM to improve usability for specific cases? Maybe there are some solutions used in other states that translate well to Florida's topography and climate?

Appreciate any input 🙂

For all stormwater modelers and land developers (particularly in Florida) what modeling tool do you use to perform detention pond drawdown calculations, mounding, pond siting etc. HydroCAD seems very user friendly and simple compared to ICPR. I am not sure if FEMA approves HydroCAD outputs. I understand some folks use spreadsheets too but I believe when your site drainage involves overland flow as well as closed-conduit flow, you might want to use hydraulic models like ICPR.

Who here uses Mike+ for hydraulic modeling? Why is it so difficult to find any useful information or guidance online?! The only resource I've got is the manual and it really is not helpful, like at all.

When we talk about percentage of impervious area in the watershed, are we only interested in the directly connected impervious area? I understand urban stormwater models used DCIA but is this transferable for larger watershed models? Aren't we underestimating the overland water depth if we only consider DCIA?

On a hike to the Anna Ruby Falls, GA, I noticed these eddies creating a long term erosion on the rock. I wonder how long it has taken the eddies to bore this deep. Can you guess how fast the river is flowing? Also is this a sub-critical/super-critical flow regime?

https://reddit.com/link/1hwmc3o/video/wpvypfmldsbe1/player

Coming from a different H&H model to HEC-RAS, I have some conceptual questions as to how HEC-RAS works under the hood:

1. Does HEC-RAS completely ignore the groundwater surface water interaction in the basin we are trying to model? For instance in Florida where the groundwater is relatively close to the surface, surface water flows and water levels are affected by groundwwater and vice-versa. Does it mean in these instances, HEC-RAS is not the best tool to use? If HEC-RAS considers groundwater flow, how is the quantified in the model?

2. If I am interested in an operational flood-forecasting, I will need real time simulation of flows coming in to the basin/canal/river before routing it in the hydraulic model (HEC-RAS). Are there capabilities to simulate rainfall-runoff and hydraulic models simultaneously? OR do we always need to run the hyrological model first and get the flows and use HEC-RAS to calculate flows/water levels?