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ISIS FEHBDY units not generating hydrographs

Posted 03/03/2016 14:51 by Ruchi

No replies yet

Hi , I have been provided a ISIS model which has been built in V3.1, however, when I am trying to run the model again in latest version of ISIS,  the ied file is not able to calculate upstream hydrographs using FEHBDY. The earlier models have been run using this ied. 

​However, now even when I am opening this ied it doesn,t generate hydrographs. Can anyone please help me if this is the ISIS version issue?

Flow Split Calculations - Low Flow Analysis

Posted 24/11/2015 10:24 by Tom L

Last post 18/03/2016 10:37

1 reply

I am currently working on a project to calculate the flow split within my ISIS model. The model consists of a single upstream channel which then splits into 4 seperate channels.

The purpose of the analysis is to understand the volume of flow going through each channel so we can calculate the flow split.  Within the main channel there are 6 deep radial gates and 6 smaller gates. We intend to replace x2 of the smaller gates with fish passes and therefore need to calculate the flow passing through these structures for design purposes.  

A single flow value has been run for each scenario which has been extended to 20 hours to try and stabilise the readings. The downstream boundary has been set to normal depth which is proving more suitable than specifying a bed slope.     

I have been experiencing a number of issues with the final results which is making it difficult to calculate the flow split. The final results aren't stable and show large oscillations in the final flow/stage readings which are unsuitable for calculating the flow split.

This is likely to be caused by the radial gate operation and so I have tried many things to rectify this problem including running different timesteps, modifying the inflows and changing the downstream boundary.

If anybody could advise me of the best approach or ideas of how I could stabilise the flow/stage values for each scenario run that would be great.

Thank you,


Zero sediment concentration imposed

Posted 24/09/2015 18:21 by jd.santos10

No replies yet

Hello, I have a question: What is the meaning of the following message:

boundary or flow reversal point found at 61 (zero sediment concentration imposed)

I´m trying to run an unsteady flow model with the sediment module but This message appears for several sections of the model, and I don´t know what is the problem.

Thanks a lot! 

1D modeling, Initial water level

Posted 02/09/2015 14:06 by Ariz Lai

No replies yet

I am currently running a model of an estuary. However, the initial water level is 0, where it should be 8m AD. How can I set it to 8m AD?

1D modelling E1100

Posted 19/07/2015 21:17 by Ariz Lai

No replies yet

I am working on a simple estuary analysis. However, it have a error code:E1100.

What should I do now?? 


 Files is in dropbox.



ReFH Urban - PR value

Posted 09/05/2015 09:16 by lchatterjee

No replies yet

The ISIS manual recommends the Percentage Runoff value for the ReFH Urban unit be set to 70%. This represents 'runoff over a paved area'. It indicates that 70% will 'drain towards' (and included in the flow estimate for the catchment) and 30% will 'drain away'.

Should this 70%/30% be applied to a 100% impermeable surface? (eg road surface)

Or is the 70/30 split for general 'urban' areas and thus accounting for gardens etc?  If this is the case, then, I'm assuming, such a split of impermeable/permeable areas shouldn't also be adjusted by the user manually.




Inlet Control Parameters - plastic culvert

Posted 26/02/2015 10:05 by johnomalley

Last post 26/02/2015 10:47

1 reply

I'm modelling a reach which has a plastic inlet and plastic conduit. I have inlet control parameters for concrete and corrugated metal but none for plastic. Where can I find these?

Thanks in advance

Parallel culverts

Posted 18/02/2015 18:27 by Jonathan Lahive

Last post 15/01/2016 10:42

6 replies

I am trying to model 2 parallel culverts, 12.5m long and 0.6m in diameter, with one pipe having a different slope to the other. What is the best way to model this? Is it possible to model 2 culverts in parallel? If so how would you go about doing it?

Thanks in advance.

Head-Time Boundary Slope Value

Posted 16/02/2015 10:06 by Aidan O' Connell

Last post 16/02/2015 13:50

3 replies

When a Head-Time Boundary is used and the Slope Calculation is specified as User, is the Slope Value/Gradient calculated as metre per metre (m/m) or metre per kilmoetre (m/km)? Any insight into this is greatly appreciated. Thanks in advance.

Modelling bends in ISIS

Posted 22/01/2015 10:39 by MGrogan

Last post 23/01/2015 17:43

2 replies

We are modelling a gauge just upstream of a significant meander system which is believed to control water levels at the gauge until it is drowned out.  We have tried using Relative Path Lengths but the losses generated by this method are not significant enough to replicate observed flows and stages at the gauge.  Is there a better way to model the individual bends and has anyone looked into modelling bend losses using ISIS?

We only have survey at the gauge US of the meander system, 1 section on the last bend of the meander system and the next section is ~300m downstream.

Spill and Culvert Junction

Posted 10/10/2014 13:25 by NP

No replies yet

Hi, I have a junction connecting a culvert unit and spill, however I am getting following error: *** error E1211 *** at label: perturbation matrix is singular stopped in spsolv It was running when I had a spill connected to the channel unit at the upstream of the culvert unit with a junction only downstream of the culvert connecting back to the channel. However, I thought that was not representing the spill as it should be an online structure! Many thanks

Set outflow boundary condition in 2D model

Posted 12/09/2014 03:04 by PRIA1984

No replies yet

Hi there, I builded a simple 2D model in ISIS Free. I used as an upstream boundary condition a hydrograph. I would like to know how to set the downstream boundary condition to allow the water flow out the model domain or active area. (The water seems to be accumulating at the end of the active area). Cheers

Entering Observed Rainfall in ReFH Boundary

Posted 29/08/2014 09:57 by Scott999

Last post 12/12/2014 11:31

2 replies

I am attempting to simulate and observed event. The FEH Boundary will allow me to input observed rainfall profile and depth. However, when attempting to do the same using ReFH boundary I am unable to as the 'Observed' button in rainfall tab will not select. Is this function not available or am I missing somthing here. Thanks

Updating X and Y co-ordinates in ISIS 1D

Posted 14/01/2014 09:00 by ajay.desai

Last post 08/02/2016 14:00

1 reply

I am trying to import ISIS .DAT file in InfoWorks ICM but need to update the X and Y co-ordinates before importing. Can someone help with the process to update the same in .DAT file?

Spill Modelling and dflood

Posted 23/10/2013 14:53 by JessP

No replies yet

I am building a model which has 4 conduits along its reach.I have modelled spills for each conduit as described in another post using junctions. When i try to run the model steady in order to get some initial conditions i get Note N3002 at 2 of the 4 spills - as per below: Model time 0.0000 hrs: *** note N3002 *** at label: HBculv2spus very small change in heads results in large change in flow at spill HBculv2spus error = 0.0005% , fw= 2.1823 I then get E1066 Calculated Water Level is higher than channel boundary at the river section upstream of the culvert this spill is connected too. I have automated preissman slot switched on and i have tried increasing dflood and still get the same result. - Try adding more section data or increasing the wall height dflood. Are the two connected at all? Or are there two+ issues to resolve? Any assistance would be appreciated! My ISIS (troubleshooting0 skills are a little rusty. Thanks Jess

Confine flow to channel

Posted 10/10/2013 15:39 by dpender

No replies yet

When running a 1D model with sections that incoporate floodplains with a lower elevation than the channel bank; how do you ensure that the flow is confined to the channel before the banks are overtopped? Cheers Doug

Crump weir configuration

Posted 27/09/2013 11:31 by iainhissett

No replies yet

I am modelling a crump weir with length of approximately 3 m. I have remote u/s and d/s cross sections and a long section down the invert of the channel and weir between the cross sections. I have duplicated the u/s cross section, placed it at the u/s end of the weir and lowered it (tying the invert in with that in the long section). I have also duplicated the d/s cross section and raised it to the d/s end of the weir. I understand that chainage needs to be conserved, but if I add the weir length into the 'distance to next section' of the cross section immediately below the weir the gradient down to the remote d/s cross section will be reduced and the head over the weir will increase. Any suggestions on how to configure crumps (or where this has been discussed already) would be appreciated. Iain

Bridgs and spills

Posted 26/08/2013 13:00 by dpender

Last post 05/01/2016 16:29

1 reply

I am trying to add a spill to a bridge section for when it becomes surcharged but I'm having problems connecting the nodes. I have u/s and d/s junctions but I'm not sure what nodes should be connected. Any help is appreciated. Doug

Roughness n = 0

Posted 02/08/2013 09:43 by fleesch

Last post 02/08/2013 09:47

1 reply

Hello, I am looking at a model that has a roughness of n = 0 for the right part of the flood plain (beyond the last panel). What is the effect of this? Someone told me this implies zero conveyance, however the results view shows water goes there (unlike the ineffective flow area in HEC-RAS). Thanks. F

Converting circular culverts to symmetrical culverts

Posted 03/07/2013 15:45 by RA222

No replies yet

Hi, Is there a quick way/useful tool available for converting a circular conduit into a symetrical one? Seem to remember i once saw a spreadsheet where you input the invert level and diameter of the circle and it would generate the equivalent chainage and elevation values for the points on the circle for inputting into a symetrical culvert node... thanks

ISIS & Barrage Modelling

Posted 22/03/2013 10:42 by JuliaLoveless

Last post 25/03/2013 10:33

6 replies

I'm currently working on a project looking into the use of flood modelling software in modelling the inundation impacts of tidal power schemes, specifically barrages. ISIS certainly seems like the best, most accessible flood modelling software I've come across so far. I have a few questions about whether this would work: 1) Can ISIS be used to calculate areas? In other words, once you have run a model is there a way to bring up a statistics table which tells you how much 'land' in the model has been inundated during the course of the model? Is this perhaps possible in the mapper tool? 2) Can ISIS translate flow into water levels? If wanting to predict the inundation of a barrage scheme, could you tell ISIS the current water level and then tell it what the water level is predicted to rise to and model this? Hope these make sense and thanks, in advance, for any help!

River bends

Posted 21/01/2013 14:34 by NickForrest

No replies yet

To model a bend in a river, am I best to use a Culvert Bend, or to simply insert a river section and use different Relative Path Lengths for each section? If the latter, I should be ticking the Panel box for each line in the cross-section, right? It seems like a very basic question, but the help files only describe 'sinuosity', and I assume that this means 'bend' but can't be sure, otherwise why wouldn't they just say 'bend'?! Thanks.

Model building in ISIS mapper - reorientation of cross sections

Posted 07/10/2012 08:24 by Jennifer

No replies yet

Hi I am builing a short model in ISIS mapper, and I have reoriented the cross-sections within the floodplain, how can I re-anayse the elevations of these sections as they are only using the original values used before the direction change. Thanks!

How to perform 2-D modeling??

Posted 04/10/2012 03:48 by yili

No replies yet

Hi, I need some help in performing simple 2-D modeling. The ISIS Guides have not explained the issue clearly. In my case, basic geometric properties of a small river are available, which should be sufficient enough for building a model. However, no GIS information is available, such as DEM. In this case, can I proceed without using GIS information? Based on the ISIS 2D Quick Start Guide, it seems that ISIS requires to apply ISIS Mapper in building a 2-D modeling. Do we have to use GIS information? Do we have any simpler but more straightforward option to delineate a small river? Can we just build a model by "drawing" a river step-by-step, as we can do in HEC-RAS? Regards Yi

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