Changing conduit roughness

[Argantonio65]

Thanks for the very nice package @bemcdonnell,

I was wondering whether it is possible to change the Manning's roughness parameter in a given conduit directly using pyswmm.

As far as I see, this is not included in the link get and change parameters.

[bemcdonnell]

@Argantonio65, Thanks!

I have a version of PySWMM that allows you to set the Manning's roughness of a conduit. How soon do you need this? I can merge in when I get some time.

[Argantonio65]

Thanks for the fast reply. I would like to be able to change roughness values within a week time. But I would not like to put any kind of pressure on you to take time for the implementation. I think adding that functionality is very interesting for pyswmm so I would encourage you to do it eventually.

However if you do not have the time to commit in this. I could try to do it myself patching my version of the package temporally. The problem is that I'm a complete profane to the SWMM API and after searching everywhere I came to a dead end.

I suspect (maybe is more difficult and I'm totally wrong) that this could be solved by adding a @property to the Links.py as set roughness:

self._model.setLinkParam(self._linkid, LinkParams.ROUGHNESS.value, parametervalue)

And adding the ID for roughness to LinkParams in the toolkitapi.py

class LinkParams(Enum):
    offset1 = 0  # double
    offset2 = 1  # double
    q0 = 2  # double
    qLimit = 3  # double
    cLossInlet = 4  # double
    cLossOutlet = 5  # double
    cLossAvg = 6  # double
    seepRate = 7  # double
    ROUGHNESS = some ID in the SWMM.dll         

Which will become a call for the Windows SWMM .dll. However I do not know which ID value corresponds to the Roughness parameter in the SWMM API.

Is there any place where this can be looked up? Or the solution is completely different?

[dickinsonre]

Hello @Argantonio65 in the C code LINK.c the Manning's n for a link is read and then used to make the value for roughness - see these lines. If you change the roughness you need to go back and change the parameters calculated from the roughness (Manning's n) as well...

Conduit[k].roughFactor = GRAVITY * SQR(roughness/PHI);

// --- compute full flow through cross section
if ( Link[j].xsect.type == DUMMY ) Conduit[k].beta = 0.0;
else Conduit[k].beta = PHI * sqrt(fabs(slope)) / roughness;
Link[j].qFull = Link[j].xsect.sFull * Conduit[k].beta;
Conduit[k].qMax = Link[j].xsect.sMax * Conduit[k].beta;

[bemcdonnell]

@dickinsonre, with the appropriate prepping of the inputs, I believe we can just call link_validate to recalculate those parameters. Am i wrong? I'll put some code up soon so you can all look at it.

[bemcdonnell]

@dickinsonre, in my initial testing, this seems to be working.

int DLLEXPORT swmm_getConduitParam(int index, int Param, double *value)
//
// Input:   index = Index of desired ID
//          param = Parameter desired (Based on enum SM_ConduitProperty)
//          value = value to be output
// Return:  API Error
// Purpose: Gets Conduit Parameter
{
    int errcode = 0;
    *value = 0;
    // Check if Open
    if(swmm_IsOpenFlag() == FALSE)
    {
        errcode = ERR_API_INPUTNOTOPEN;
    }
    // Check if object index is within bounds
    else if (index < 0 || index >= Nobjects[LINK])
    {
        errcode = ERR_API_OBJECT_INDEX;
    }
    else if ( Link[index].type != CONDUIT)
    {
        errcode = ERR_API_WRONG_TYPE;
    }
    else
    {
        int k = Link[index].subIndex;
        switch (Param)
        {
            case SM_LENGTH: 
                *value = Conduit[k].length * UCF(LENGTH); break;
            case SM_ROUGHNESS:
                *value = Conduit[k].roughness; break;
            case SM_BARRELS:
                *value = (double)Conduit[k].barrels; break;
            default: errcode = ERR_API_OUTBOUNDS; break;
        }
    }
    return(errcode);
}

int DLLEXPORT swmm_setConduitParam(int index, int Param, double value)
//
// Input:   index = Index of desired ID
//          param = Parameter desired (Based on enum SM_ConduitProperty)
//          value = value to be input
// Return:  API Error
// Purpose: Sets Conduit Parameter
{
    int errcode = 0;
    int us_node, ds_node;
    // Check if Open
    if(swmm_IsOpenFlag() == FALSE)
    {
        errcode = ERR_API_INPUTNOTOPEN;
    }
    // Check if Simulation is Running
    else if(swmm_IsStartedFlag() == TRUE)
    {
        errcode = ERR_API_SIM_NRUNNING;
    }
    // Check if object index is within bounds
    else if (index < 0 || index >= Nobjects[LINK])
    {
        errcode = ERR_API_OBJECT_INDEX;
    }
    // Check if is Conduit Type
    else if ( Link[index].type != CONDUIT)
    {
        errcode = ERR_API_WRONG_TYPE;
    }
    else
    {
        int k = Link[index].subIndex;
        double elev = 0;
        switch (Param)
        {
            case SM_LENGTH: 
                Conduit[k].length = value / UCF(LENGTH); break;
            case SM_ROUGHNESS:
                Conduit[k].roughness = value; break;
            case SM_BARRELS:
                Conduit[k].barrels = (char)(int)value; break;
            default: errcode = ERR_API_OUTBOUNDS; break;
        }

        // This code re-establishes the offsets as elevations
        // since it will be reconverted back to offsets if the 
        // mode is in ELEV_OFFSET. 
        // Get node indeces (Depends of Flow Direction)
        if (Link[index].direction == 1)
        {
            us_node = Link[index].node1;
            ds_node = Link[index].node2;
        }
        else
        {
            us_node = Link[index].node2;
            ds_node = Link[index].node1;
        }
        // Set offset
        if (Param == SM_OFFSET1)
        {
            if ( LinkOffsets == ELEV_OFFSET ) elev = Node[us_node].invertElev;
            Link[index].offset1 = elev + value / UCF(LENGTH);
        }
        if (Param == SM_OFFSET2)
        {
            if ( LinkOffsets == ELEV_OFFSET ) elev = Node[ds_node].invertElev;
            Link[index].offset2 = elev + value / UCF(LENGTH);
        }
        // Re-validate link
        link_validate(index); 

    }
    return(errcode);
}

[AnmaTech]

HEllo;

I wonder whether it is possible to change the Manning's roughness parameter in a given conduit using last version of pyswmm?

Did you put these changes in library?

Thanks

[bemcdonnell]

@anmatech, let me see what I can do. I have these changes in my private fork of pyswmm. Let me see what I can do to bring them in

[Argantonio65]

@bemcdonnell Was this finally merged into pyswmm? I saw that the link parameter pointers do not show roughness as an option.

Thanks a lot

[bemcdonnell]

@Argantonio65, circling back to your question - I haven't merged it in but if you want to take over that pull request, we can help you through the process!

[juanaherran]

Hello!

I would like to know if the latest version of pyswmm allows to change the roughness of the pipes.

Thanks a lot.

[jennwuu]

Hey @juanaherran, at the moment, you will need to adjust the model swmm input file manually before using pyswmm.

[theafromhust]

Hi, I wonder if the latest version of pyswmm allows to change the roughness or the diameter of the pipes.

Thanks a lot

[bemcdonnell]

Completed with pyswmm-v2