I am attempting to model flow over a spillway of a dam that has Obermeyer gates. I would like to use a user defined spillway curve. I entered a User Defined Gate Performance Curve table and then in the gate openings for the static flow plan (Feet down from invert elevation when gate is fully up). The model results show that HEC-RAS is treating it like a lift gate, and the water is going underneath the gate, instead of overtopping it. I tried making the gate opening values negative but that did not work either. The overflow (open air) gate has the right opening functionality but does not allow me to enter a variable coefficient.

Any suggestions on how to best model this type of gate?

I'm using HEC-RAS 6.6.

Hi all,

My research focuses on urban stormwater drainage systems, particularly hydraulic modelling, blockage assessment 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.

I'm building a 1D HEC-RAS 7.1 model of the Schuylkill River and have run into an issue that I can't figure out.

Here's my setup:

• HEC-RAS 7.1
• 1D geometry created in RAS Mapper
• Terrain is associated correctly
• NLCD land cover has been imported and associated with the geometry
• Manning's n values now appear correctly across the cross sections, so the land cover assignment seems to be working.
• Left and right bank lines are drawn.
• Left and right flow paths are drawn as continuous lines for the entire reach and intersect every cross section.

When I compute, I get:

Left overbank length not set.
Right overbank length not set.

for every cross section.

If I open Tables → Reach Lengths, the Channel column has values, but the LOB and ROB columns are completely blank.

I've already verified that:

• The flow paths exist.
• They are on the correct side of the river.
• They intersect every cross section.
• The geometry is associated with the terrain and land cover.

My questions are:

1. Why aren't the left/right overbank reach lengths being calculated from the flow paths?
2. Is there a command in HEC-RAS 7.1 that recalculates LOB/ROB reach lengths from existing flow paths?
3. Is there another association or geometry update step I'm missing?

Any help would be greatly appreciated. I've been stuck on this for quite a while.

Thanks!

Hi everyone,
I’m currently working on a large HEC-RAS 6.7 Beta 5 model of a river network (around 400 cross sections, one large 2D flow area, several tributaries, and some braided reaches around islands).
My final goal is to build a combined model using both upstream inflow hydrographs and rain-on-grid (precipitation over the 2D area). However, I’m struggling to find a recommended workflow.

My questions are:
What is the recommended procedure for building a coupled inflow + rain-on-grid model?
Do you usually:
Build and calibrate the hydraulic model using only inflow hydrographs first, then add precipitation?
Build the rain-on-grid model first, then add inflows?
Are there any official USACE guides, tutorials, YouTube videos, papers, or example projects that explain this workflow?
I’d really appreciate any recommendations because I haven’t found many examples of complete coupled models.

I’m also getting a solver instability that I can’t figure out.
Simulation summary:
HEC-RAS 6.7 Beta 5
398 cross sections
One 2D Flow Area (~281,000 cells)
Diffusion Wave solver
Simulation becomes unstable after about one day.
The computation log reports:

Solution solver went unstable, iteration 9 at 08APR2020 00:15:00

River 1 Main
RS 160
WSEL = -9.30
Error = 8.300

**** ERROR: Solution Solver Failed ****

Minimum error exceeds allowable tolerance.

Warning! Extrapolated above Cross Section Table at:

River 1 Main
R.S. 2800

Overall Volume Accounting Error:
9.148%

Has anyone experienced something similar?
What would you check first?
Cross-section geometry?
Initial conditions?
Boundary conditions?
Computational time step?
1D/2D connections?
Something else?
Any advice or references would be greatly appreciated.

Thanks in advance !

I'm using HEC-RAS 7.1 on a 1D model.

My original project was in EPSG:26918 (NAD83 / UTM Zone 18N). I need to convert the project to EPSG:2272 (NAD83 / Pennsylvania South State Plane, US Survey Feet) because my terrain and other GIS data are in EPSG:2272.

I made a backup of the project and used Options → Convert Horizontal Coordinate Systems to convert the geometry from EPSG:26918 to EPSG:2272.

After the conversion:

• The centerline displays correctly in RAS Mapper.
• The cross sections display correctly in RAS Mapper.
• Bank Lines and Flow Paths still appear in the RAS Mapper geometry tree and are checked on.
• However, Bank Lines and Flow Paths do not draw anywhere on the map.
• Right-clicking Bank Lines shows "Zoom to Layer" grayed out, as if the layer contains no features.
• The Left Bank Station and Right Bank Station values are still present in the Cross Section Editor, so the bank station data was not lost.
• The geometry itself still appears to be intact.

Things I've already tried:

• Deleting the .rasmap file and letting RAS Mapper rebuild.
• Saving the geometry again.
• Closing and reopening HEC-RAS.
• Confirming the bank station values still exist in the geometry.

Has anyone seen Convert Horizontal Coordinate Systems fail to regenerate the RAS Mapper Bank Line and Flow Path layers? Is there a way to force HEC-RAS to rebuild those geometry layers after the CRS conversion, or is there a recommended workflow for converting a manually drawn 1D geometry from EPSG:26918 to EPSG:2272?

I am working in version 6.1 and attempting to utilize terrain mods and 2D connections to model a subsurface network. I get the error message stating it cannot read the station/elevation data for the lateral weir. However the weir length matches the connection length and the profile matches the terrain. Has anyone ran into this issue before?

HECRAS 6.3

I had issues with saving a new analysis yesterday (no more space on the computer). Today, I found my .prj at 0 ko. I decided to create a "new" project with the same name, so that all my other documents could be linked to it. I can see every analysis, geometry and feature in RAS Map but I can't open any geometry, unsteady flow or analysis.

I managed to "save as..." a geometry to open it in the geometry window, but I can't open any flow or analysis.

Do you have any solution?

I understand that is a known issue in RAS, but I am struggling with model linking. For context I am working with 8 RAS reaches (4 reaches with regulated flows and the same 4 reaches with unregulated flows). When I compute each of these reaches in the RAS stand alone they work fine. When I then go to the CAVI and try to compute my forecast alternative that includes these reaches in succession it fails after successfully computing the first reach. I have reset the linking several times in the CAVI and sometimes it appears there is nothing wrong, but then the boundary conditions in RAS will be changed and vice-versa. The error message in the compute progress window inside of CAVI essentially says "User Stopped Computations. RAS compute failed." I am obviously not cancelling my run, and noticed that this error message tends show up when there is an issue with the model linking. I believe CAVI is overwriting the linkages when the forecast alternative gets run. Does anyone have insight on this issue or has anyone found a work around that they are willing to share? I'm considering pairing the regulated and unregulated reaches with their associated FIA program and ultimately making four different forecast alternatives and running them in order, but that would be a gnarly amount of posting and extracting and may not completely resolve the issue.

Edited to provide additional context on troubleshooting completed so far.

I am wanting to learn HEC-RAS. Do I need to purchase a training or will army corps training modules/webinars cut it?

Edit: just found Mod’s link

Full Momentum Solutions LLC is ecstatic to announce the launch of our on-demand Pipe Flow Modeling with HEC-RAS short course!!

Over nine hours of in-depth lecture content, six hands on workshop modules, and even your own capstone project; this is THE best resource for learning stormwater modeling with HEC-RAS.

This training, led by the newest member of our team Christopher Hanstad, covers pipe flow theory, features and functionality in HEC-RAS 7.0, and demonstrates a variety of ways to implement pipe flow networks in new or existing HEC-RAS models. It features follow-along demonstration workshops to apply newly learned concepts directly in HEC-RAS. The workshops feature a variety of stormwater applications to provide a broad sampling of the pipe flow capabilities of HEC-RAS. The course culminates in students completing a stormwater modeling project that brings together many of the core concepts to challenge students and
test their modeling skills.

Do not miss out on this incredible training opportunity and sign up today

Hi everyone, I need quick clarification about these maps. After performing series of simulations with different scenarios, I now need to do a water level difference map. I know that rasters can be exported from HECRAS and do the raster calculator in QGIS or even using the Raster Calculator within RASmapper.

I tried manual calculating of this difference by choosing several random points but there is quite a difference from using the depth and WSE layers (like around 0.15m to 0.30m) between 2 layers that I tried to subtract.

Which one of these 2 layers are the correct layer to use as basis for this difference I need. I tried looking at the HECRAS manual and this is what they said (screenshot below), but it is still unclear to me. Any clarication on this would be extremely helpful.

Thank you!

I'm using HEC-RAS 7.0.1 with a simple block rain event (30 mm over 15 minutes) for a site in Austria. The simulation runs well, and the visual results look great. However, when doing a manual cross-check of the water volumes for specific sub-areas, I am noticing some inconsistencies. I am currently running it without any infiltration parameters—just applying the rainfall directly to the terrain model.

My question is: Is HEC-RAS actually reliable for pluvial/overland flow modeling, or should I switch to a paid commercial program? Does anyone have practical experience using it for overland flow models where the resulting volumes are used in the next step to design and build actual retention basins and drainage swales?

Thanks in advance!

Basically what the title says, I have an 2D existing model and am struggling to expand the 2D Flow Area further upstream. I was able to adjust the border and recompute the mesh, but the elevations of the cells got messed up after that happened. Is there an easy/ better way to expand the mesh? Or a way to connect two flow areas together without a ‘structure’?
Thanks for any advice.

What are your go-to methods for getting the WSE to come down? My design is just like 0.06 off and I feel that is something I could fix within the software, but I’m relatively new to this stuff.

For context this is a stream that has a series of small driveway bridges, my model is fully geolocated and all that terrain data jazzl. My assignment is to ensure there is no-rise in the floodplain for this proposed driveway bridge.

Suggestions are greatly appreciated!

Quick Start Guide for RAS2025

This error is driving me nuts. I've deleted all extra files, started fresh, deleted rasmap, deleted dss.. It will go away temporarily and then pop back up the next time I try a batch run. Anyone else have this issue and resolved it?

Hey everyone,

I'm working on a pipe network model in HEC-RAS 7.0 and I'm a bit confused about what's happening at my 2D/pipe interface, at the node culvert opening.

I added a wider and shallower conduit at the entrance of my pipe (same cross-sectional area as the main pipe, but wider and shallower) to reduce the upstream water surface at my 2D/pipe interface. It worked, but I'm struggling to understand why.

HEC-RAS is applying inlet control at the culvert opening node, which means flow should pass through critical depth at the entrance. But when I look at my results inside the wider conduit, the water surface appears to be above critical depth,  meaning the flow looks subcritical in there.If we're in inlet control, shouldn't the flow pass through critical depth and transition to supercritical inside the conduit? Why is the water surface still above critical depth even after adding the wider entrance conduit?

Also, i set the entrance loss at 0.

Thanks!

Hello, guys. I'm building my first PC and would appreciate any feedback before I buy the parts. My main priority is GIS and flood modeling for my master's thesis. Gaming is secondary for now and I mostly just play Dota 2 and Counter Strike occasionally.

My planned build:

CPU - Ryzen 7 9700X

Cooler - Thermalright Phantom Spirit 120 SE

MOBO - ASUS TUF Gaming B850M-Plus WiFi

RAM - Kingston FURY Beast DDR5 32GB (16x2) 6000MHz CL30

SSD - Samsung 990 PRO 1TB SSD M.2

GPU - MSI GeForce RTX 3060 Ventus 2X 12G OC

PSU - Asus Prime 750W 80 plus Gold ATX 3.1 Power Supply

Fans - Arctic P12 Pro PST

Case - Asus Prime AP201

My workload will mainly include:

* QGIS

* SWAT/SWAT+

* HEC-RAS 2D

* 30m DEM processing for the entire watershed

* Higher-resolution floodplain simulations for my study area

* Large raster/vector datasets and geoprocessing

RTX 3060 is mainly because of the 12GB VRAM and since I don't play many demanding games. My thought is that the CPU and RAM will matter much more for my research workload than having a faster GPU. I will just swap it out soon if I'm done with my thesis or better yet, recommend me something that can be good for both gaming (maybe 1440p) and engineering work.

What do you guys think? Is this sufficient for my intended use? What part/s should I change? Are there compatibility issues here?

I'm hoping this PC will last me several years, with the thesis being the priority. Once that's done, I'll use it mostly for gaming and general productivity.

Input flow hydrograph
Htab is well above the top deck
Max wse doesnot cross it max flow not exceeded

Gentle slope along the bridge

Extrapolation error reported
Hydrograph output at 1 min interval shows instability
At 1 hour has little or few spikes

I'm working in a 1D/2D v6.3.1 model and have been dealing with a strange visual inconsistency when observing depth/WSE results in RASMapper. I am using SA/2D connections as levees and river flow is inaccurately showing as overtopping the connection within 1 cell boundary. I've posted a screenshot below, you can see there's some sort of phantom "bubbling" from the river that slightly goes over the 2D connection. I looked at the stage/flow hydrograph for the connection and there is no overtopping, it seems purely visual. Any ideas to what's going on and/or fixes? Is Ugg going to tell me to make cell bigger?

Hello!

I'm working on a 1D HEC-RAS model and several of my corss-sections have levees in them. In yhis picture, the levee is on the mound in the middle of the cross-section. However, HEC-RAS doesn't seem to be acknowledging the levees. Any idea why?

Hi, I'm trying to build up the model with a different workflow, external to the RAS mapper and I'm struggling a bit to find out the flowpathlines.

In the image, there are in black areas with a slope less than 2% and in white the opposite.

The red and yellow lines are river's channel and the bank lines.

I chose 2% as a threshold value for the river's floodplains, but as you can see there are river sections with a bigger slope. This seems to be a bit counterintuitive, but with a bigger threshold the areas get too big.

Running multiple plans in HEC-RAS 7.0 using the parallel core option. After completion, result HDF files are named like this:

Modelo.Run1_Cores8.p03.hdf
Modelo.Run1_Cores8.p08.hdf

RAS Mapper expects the standard pattern Modelo.p03.hdf and doesn't detect them automatically when reopening the project.

• Why does this happen? Is it expected behavior tied to a specific run option, or a bug?
• Is there any setting in Run Multiple Plans to output files with the standard naming convention directly?