Comparison of the H2OMAP SWMM5 Hazen Williams Force Main Solution to a HW Solution

Note:  Comparison of the H2OMAP SWMM Hazen Williams Force Main Solution to a HW Solution

In this example, we compare the force main head loss in four links in H20Map SWMM to the head loss in a steady state HazenWilliams solution for the same length pipe, diameter and flow (Figure 1).  The H2OMap SWMM model has a large constant dry weather inflow at the wet wells which floods the wet well and causes a constant pump flow to the force main (Figure 2).  TheHW calculator is located here http://www.engineeringtoolbox.com/william-hazens-equation-d_645.html and a comparison forHW head loss in PSI for 5000 feet long, 3 inch diameter pipes with HW Coefficients of 130, 120, 110 and 100, respectively, is shown in Table 1.   The SWMM 5 equation loss (PSI Diff) and the PSI loss from the HW calculator are very close for all four links. 

Table 1.  Steady State comparison between HW Calculator and H2OMAP SWMM/SWMM 5 Force Main calculations.

HW	SWMM5	SWMM5	SWMM5 Loss	Loss
Coefficient	Psi UP	PSI Dn	PSI Diff	PSI HW Calculator
130	84.563	44.88	39.683	39.82
120	88.772	43.765	45.007	45.16
110	91.798	41.426	50.372	50.54
100	95.354	38.727	56.627	56.82

Figure 1.   H2OMAP SWMM Wet Well, Pump, Force Main and Gravity Main Network.

Figure 2.  Constant Pump Flows

How to Compare the Output Manager Statistics in H2OMAP SWMM to the SWMM 5 Output Text File

Subject:   How to Compare the Output Manager Statistics in H2OMAP SWMM to the SWMM 5 Output Text File

  

The value of the total inflow in the text output file is the integrated total for the whole simulation including all time steps.   This is the total volume that is shown in Map Display for Nodes and Links or in the Summary Tables for Nodes and Links.   If you graph the flow or depths in Output Report Manager and use the FieldStatistics tool it will only show you the statistics for the SAVED time steps.  However, if you multiply the Sum (Total) Value by the saved interval in seconds you will have another estimate of the total node of link  statistic.  For example, a Sum Total of L/s times seconds yields liters which divided by 1,000 yields ML. 

Figure 2.  Map Display of  the  total link volume in the model run comes from the Node Inflow Summary Table in the Text Report File

  ***********************

    Node Inflow Summary

  ***********************

  -------------------------------------------------------------------------------------

                                  Maximum  Maximum                  Lateral       Total

                                  Lateral    Total  Time of Max      Inflow      Inflow

                                   Inflow   Inflow   Occurrence      Volume      Volume

  Node                 Type           LPS      LPS  days hr:min    10^6 ltr    10^6 ltr

  -------------------------------------------------------------------------------------

  PN_060               JUNCTION      0.00     2.93     0  07:47       0.000       0.143

Advanced SWMM 5 import into InfoSWMM and H2OMAP SWMM

Subject:  Advanced SWMM 5 import into InfoSWMM and H2OMAP SWMM

The current version of InfoSWMM and H2OMAP SWMM not only imports the latest SWMM 5 version but it has built in flexibility that allows the user to import selected data sections, model data sections or auxiliary file information such as calibration data files.  This allows you the choice of importing non specific network data that can used in the model of any city, county, shire, town or watershed.  For example,  you can import only these sections without affecting the geometry of your network:

1.      Calibration File Information,

2.      RTC Rules

3.      Aquifers

4.      Snowpacks

5.      Buildup for Water Quality,

6.      Washoff for Water Quality,

7.      Evaporation,

8.      Time Series,

9.       DWF,

10.        Patterns,

11.        RDII

12.        Loadings,

13.        Curves,

14.        LID Controls,

15.        LID Usage,

16.        Pollutants,

17.        Land Uses

Possible uses of this feature would be to have a city wide or company wide library of LID controls, RTC Rules or RDII values.

Figure 1.  Import Dialog with Import Options

Figure 2.  Only names and directories of the Calibration Files was imported

The SWMM 5 1D Components in InfoSWMM 2D

Note:  The SWMM 5 1D Components in InfoSWMM 2D

InfoSWMM 2D uses standard SWMM 5 components to connect the 1D Nodes to the 2D Mesh.  A bottom outlet orifice at the maximum depth of the node drains to a SWMM 5 Outfall at the fixed elevation equal to the Node Rim Elevation. Flow can go into or out of the Outfall from the 1D element from or to the 2D Mesh. InfoSWMM 2D automatically makes the necessary elements if 2D is used and the new elements are listed in the Hydqua.inp file, which is very similar to the Tab Delimited SWMM5 Input file. 

The HYDQUA.inp is very similar to the Excel Tab formatted file of SWMM 5 with a few additional sections and added features:

1^st Difference:   The Flood Node Data Section tell the 2D engine which Node has a 1D-2D connection and which 2D mesh element the 1D Node drains to when it is flooded.

[Flood_Node]

10309D      848

80408        131

2^nd Difference:  Outfall Nodes are created for the 2D Mesh Element connected to the 1D Node, the outfalls are Fixed Outfalls and the fixed head is the Node Rim Elevation of the 1D node listed in the Flooded Node Section

[OUTFALLS]

10208  89.900000     FREE  NO

10208A           89.900000     FIXED            94.400000     YES

10208B           89.900000     FREE  NO

10208C           89.900000     FREE  NO

10208D           89.900000     FREE  NO

10208E           89.900000     FREE  NO

10309D_OUTFALL           101.600000            FIXED           111.000000            NO

80408_OUTFALL             120.000000            FIXED           133.400000            NO

3^rd  Difference:  Bottom Outlet Orifices are created to connect the 1D node to the 2D Mesh Element Outfall with the Flood Discharge Coefficient entered by the user and a crest height equal to the maximum depth of the node

[ORIFICES]

OR1@82309B-15009B  82309B      15009B      BOTTOM    0.000000   0.850000   NO

OR1@82309D-82308D  82309D      82308D      SIDE 0.000000   0.850000   NO

10309D_ORIFICE       10309D      10309D_OUTFALL       BOTTOM    9.400000   0.030000   NO

80408_ORIFICE          80408        80408_OUTFALL         BOTTOM    13.400000 0.030000   NO  

H2OMAP Sewer and InfoSewer Water Quality Options

Subject:   H2OMAP Sewer and InfoSewer Water Quality Options

You can model 8 options in H2OMAP Sewer and InfoSewer to simulate various aspects of Water Quality (Figure 1).  If you make the base scenario no water quality you can have the same network, same loading but different aspects of water quality in seven child scenario's (Figure 2).  The parameters for each water quality option is shown in the Quality Tab of the SimulationOptions Dialog.

Figure 1.  Water Quality Simulation Choices in H2OMAP Sewer and InfoSewer.

Figure 2.  Water Quality Simulation Choices in the Scenario Explorer of H2OMAP Sewer and InfoSewer

How Dry Weather Flow is Used in InfoSWMM at a Node

Note:   How Dry Weather Flow is Used in InfoSWMM at a Node

There are four components to the Dry Weather Flow (DWF) in InfoSWMM:

1.       The mean flow in user units at the node,

2.      The DWF Allocation Code – if you are using the DWF Allocator

3.      The Pattern for Weekday, Weekend etc for the mean flow.

The data is entered or entered for you in the Node Inflow Icon or the Operations Tab of the Attribute Browser

Node Inflow Icon and Associated Data

Operation Tab Patterns

You can also make global changes to your DWF using the Node DWF DB Table Under Extended Element Modeling Data

All Possible Culverts Example Model in SWMM5

Note:  Attached is an example SWMM 5 model that has all 57 culvert types possible in SWMM 5 in one model.  The culverts are 57 small individual networks consisting of an inflow node, an upstream open channel, upstream node for the culvert, culvert link with culvert code, downstream node of the culvert, downstream open channel and finally an outfall node.  The culvert code and the shape of the culvert determine which FHWA equation is used to determine the flow INTO the Culvert during the simulation:

1.   The flow from the St Venant Equation or

2.   The flow from the FHWA equation

The minimum flow is used by the program. 

Weir and Orifice Flow Equations for a Weir in SWMM 5

Weir and Orifice Flow Equations in SWMM 5!

1. 🌊 When we discuss the weir flow equation in SWMM 5, it's essential to understand that the weir equation is applied under specific conditions. The head (or height of water) at the weir should be between its base (invert elevation) and the top (crown). This is when the weir equation is most applicable.

2. 🕳️ Once the water level surpasses the weir crown, indicating that the weir is submerged or the head is exceptionally high, the orifice equation comes into play.

It's crucial to ensure the accurate application of these equations, as they determine the flow of water in stormwater systems and can greatly influence flood predictions and management.

Three Inertial Term Options in SWMM 5 and InfoSWMM/H2OMAP SWMM

Subject:  Three Inertial Term Options in SWMM 5 and InfoSWMM/H2OMAP SWMM

The dynamic wave flow in SWMM5 and InfoSWMM is calculated from the following equation

Q  =   (Qold – dq2 + dq3*sigma +  dq4*sigma ) / ( 1  + dq1 + dq5)

Where,

Qold               =         Last Time Step Flow in the Link

dq1                 =         friction loss term

dq2                 =         water suface slope + bed slope term

dq3                 =         midpoint area non linear term

dq4                 =         upstream and downstream area non linear term

dq5                 =         Entrance, Other and Exit Loss Term

sigma            =         function of the Froude number and a function of the Three Intertial Term Options

Figure 1 shows how Sigma is set based on the user selection of the Three Intertial Terms.  Figure 2 shows how Sigma is calculated for the Dampen Option.  If you use Ignore then dq3 and dq4 are ignored all of the time, if you use Dampen then dq3 and dq4 are used for a Froude number less than 0.5 and then the terms gradually fade away until a Froude number of 1 is reached.   If you use Keep then the non linear terms are used all of the time no matter the value of the link Froude Number. There is one exception to this rule: If a closed link is full then the value of sigma is set to 0.0 no matter what is selected for the Intertial Term.

Figure 1.  The value of Sigma for each of the Three Inertial Term Options in SWMM 5 and InfoSWMM/H2OMAP SWMM

Figure 2.  At each iteration for each link during the simulation the link Froude Number is calculated and based on the Froude Number the value of Sigma is Set.

Link Simulated Parameters used in either the Normal Flow or St Venant Equation of SWMM 5

Subject:  Link Simulated Parameters used in either the Normal Flow or St Venant Equation of SWMM 5

St. Venant equation – this is the link attribute data used when the St. Venant Equation is used in SWMM 5.  Simulated Parameters from the upstream, midpoint and downstream sections of the link are used.

Normal Flow Equation – this is the link attribute data used when the Normal Flow Equation is used in SWMM 5. Only simulated parameters from the upstream end of the link areused if the normal flow equation is used for the time step.

Exit, Other and Entrance Loss Values in SWMM 5, InfoSWMM

Subject:  Exit, Other and Entrance Loss Values in SWMM 5, InfoSWMM

The entrance, exit and other losses in SWMM 5 are computed at the upstream, downstream and midpoint of the sections of the link.  However, if the normal flow equation is used for the link during a time step then these losses are zero as the flow in the link is based solely on the upstream area and upstream hydraulic radius of the link.   If you add loss coefficients and the normal flow equation is used then you will not see any change in the flow as you modify the loss coefficients.

The Groundwater Flow Component in SWMM5

Subject:  The Groundwater flow in SWMM 5 Groundwater

The Groundwater flow in SWMM 5 is actually made up of three components:

1.   A groundwater flow computed from the coefficient a1 and exponent b1

2.   A groundwater flow computed from the coefficient a2 and exponent b2 and

3.   A Surface Water / Groundwater Interaction coefficient a3

The total Groundwater flow is the sum of the flow from 1, 2 and 3 – normally 2 is the opposite of 1.

RDII Initial Abstraction in SWMM 5

Subject:  RDII Initial Abstraction in SWMM 5

The initial abstraction in each of the three components of RDII in SWMM 5 are updated at each time step.  The initialabstraction (ia) is:

ia = iaMax - iaUsed

based on the maximum amount of ia, the ia used (iaUsed), the recovery rate (iaRecov) and the month and class of RDII.  You can enter a value for iaMax, iaInit and iaRecov for each month.

The iaUsed at the beginning of the simulation is set equal to iaInit

and if there is no rainfall

RDII Parameters for SWMM 5

Subject:  RDII Parameters for SWMM 5

There are three types of RDII Response, six different parameters and an annual and optional twelve monthly sets of distinctparameters.

.

Steady State Flow Analysis in InfoSWMM using a Ramp DWF

Subject:  Steady State Flow Analysis in InfoSWMM using a Ramp DWF

This can be easily created using a few steps in InfoSWMM. 

Step 1:  Using Scenario Explorer make a cloned Child Scenario and a cloned DWF Set which will be later modified.

Step 2:  Using DB Manager and the BlockEdit tool and increase the mean DWF by a factor of 10, 100 or 1000 to drown out all Wet Wells and cause the pumps to turn on and stay turned on during the simulation in the newly created DWF Set.

Step 3.  Run the batch manager and create two output files – Normal and Steady State for comparison.

Step 4.  You can now compare the two scenario's using Output Manager and the Compare Graph tool.  The Ramped Model should have constant flows in both links and pumps.  It was not necessary to change any of the patterns.

Step 5.  The model is still  in balance – the excess DWF Inflow ends up as flooded flow and is listed as Internal Outflow.