Multiple Storm Events in InfoSWMM and How to Use them in the Scenario Manager

Subject: How to make Multiple Storm Events in InfoSWMM and How to Use them in the Scenario Manager

Step 1. Make a new Time Series to hold the data points for your new Rainfall Time Series in the Operation Tab of the Attribute Browser.

Step 2. Populate the Rainfall Distribution with a SCS Type II Hyetograph with a 1 inch rainfall total

Step 3. Now Clone the created Rainfall Distribution and make 10, 25, 50 and 100 year storm events each with 1 inches of rainfall in a cumulative distribution.

Step 4. Now use the Block Edit command and convert each of the newly created hyetographs to 4, 7, 10, 15 and 20 inch cumulative rainfall totals from the original 1 inch rainfall total (for example).

Step 5. Now create a Raingage for each of the newly created hyetograph time series using the DB Editor under the Raingage Table in Hydrologic Data

Step 6. Link the Time Series to the new Raingages and define the type (cumulative), units (inches) and hyetograph interval (15 minutes)

Step 7. Make 4 New Scenarios for the different return period hyetographs, the Base Scenario will use the 5 year or 4 inch SCS II rainfall.

Step 8. Use the DataSet Manager and make 4 new Subcatchment DB Tables in which each Subcatchment Set uses a different return period hyetograph.

Step 9. Run the Batch Simulator for all 5 scenarios including the Base Scenario.

Step 10. You can use the Output Report Manager to see the Rainfall for all of the Batch Runs to check if the proper rainfall was used for each Scenario Simulation.

 

 

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Reserve Capacity and Reserve Flow in a Link in InfoSWMM and SWMM 5

Subject:  Reserve Capacity and Flow in a Link

The Reserve flow and Reserve Capacity are modeling guidelines and do not actually influence the computed flows in a link.  If you have a positive Reserve flow or capacity then you MAY get more flow in the link based on the current flow being less than the Qfull for the link but not if the link is under surcharge, has backwater conditions or has large entrance and  exit losses. You cannot always assume that because the Reserve flow is positive the link can  handle more upstream flow.

Here are few graphs that show the relationship between Qfull, the actual Q in the link and the Reserve Flow or Reserve Capacity.  The Qfull is a reference flow and is not used during the computation in InfoSWMM and SWMM5.

Condition 1:   Positive Reserve Flow – the flow is always less than Qfull and the Reserve flow and  Reserve Capacity are Positive.

Condition 2:   Negative Reserve Flow – the flow is sometimes greater than Qfull and the Reserve flow and  Reserve Capacity are negative when this occurs.

Reserve Capacity – the Reserve in the link * the current link volume.

What Node and Link Invert Elevations Does SWMM 5 Use?

Note:  What Node and  Link Invert Elevations Does SWMM 5 Use?

SWMM 5 uses the following Node information from the user:

·         Node Invert Elevation,

·         The Node Rim Elevation which is the Node Invert Elevation + the Maximum node depth

·         The Ponded Area when the Ponded  Area option is used

·         The Surcharge Depth above the Node Rim Elevation

SWMM 5 uses the following link information from the user:

·         The Link Upstream Offset Depth or Offset Elevation and

·         The Link Downstream Offset Depth or Offset Elevation

·         The Link Maximum Depth or Diameter

SWMM 5 calculates the following information internally:

·         The Pipe Crown Elevation at the upstream and downstream link nodes.  The Pipe Crown is the Pipe Diameter + Link Offsets

·         The Node Highest Pipe Crown Elevation,

·         The Surcharge Depth above the Rim Elevation if the Node has a Surcharge Pressure Depth at the Node during the simulation,

o   If the Surcharge Depth is 0 then the program will either lose the flooded water or store the flooded water during the simulation

·         The Flooded Depth above the  Rim Elevation if the Node uses the Ponded Area Option

o   You have to enter a Ponded Area for the node AND use the Global Allow Ponding Option

SWMM 5 Rules for Pipes

·         The Pipe Invert Cannot be below either upstream or downstream node invert – the program will print a warning in the rpt file and set the offset to 0 internally,

·         The Pipe Crown Cannot be above the Rim Elevation of the Node – the program will raise the Rim Elevation when this happens and print a warning in the rpt file.

The use of Offset Depth or Offset Elevation for the Link Offsets is based on the user choice at the bottom of the SWMM 5 GUI Map.

Or in the Tools/Preference/Operation dialog of InfoSWMM/H20MAP SWMM 

InfoSewer Static Gravity Main Report

Note:  Static Gravity Main Report

Shows steady state simulation results for all gravity mains in tabular format. The report displays one record for each gravity main in the current H2OMAP Sewer project.  Gravity main report columns include the Node Identifier, Total Flow, Unpeakable Flow, Peakable Flow, Coverage Flow, Infiltration Flow, Storm Flow, Flow Type, Velocity, d/D, q/Q, Water Depth, Critical Depth, Full Flow, Coverage Count, Backwater Adjustment, Adjusted Depth and Adjusted Velocity.

The following variables are displayed on the Static Gravity Main Report in the Output Report Manager for all or selected gravity mains:

1.       ID - Gravity main identifier.

2.       From Node - ID of upstream node.

3.       To Node - ID of downstream node.

4.       Diameter - Inside pipe diameter for circular channels, in (mm).

5.      Channel Depth - Maximum depth of a conduit (for non-circular channels only), in (mm).

6.      Channel Width - Top/Bottom width of a conduit (for non-circular channels only), in (mm).

7.      Channel Left Slope - Left side slope of a conduit (for trapezoidal and triangular channels only).

8.      Channel Right Slope - Right side slope of a conduit (for trapezoidal and triangular channels only).

9.       Length - Pipe length, ft (m).

10.   Slope - Ratio of the change in vertical distance to the change in horizontal distance, unitless.

11.   Total Flow - The summation of all flow types, flow unit.

12.   Unpeakable Flow - The flow to which no peaking is applied, flow unit.

13.   Peakable Flow - The flow derived based on the Federov peaking equation, flow unit.

14.   Coverage Flow - The flow derived based on the Harman and Babbitt peaking equation in reference to the contributing population, flow unit.

15.   Infiltration Flow - The volume of groundwater entering the sewer system from the soil through defective joints, broken or cracked pipes, improper connections, or manhole walls, flow unit.

16.   Storm Flow - Peak storm load in the pipe, flow units.

17.   Flow Type - Indicates if the flow is pressurized or free surface.

18.   Velocity - The speed with which the water is traveling through the pipe, in ft/s (m/s).

19.   d/D - The ratio of actual flow depth to the diameter of the pipe (full flow depth), unitless.

20.   q/Q - The ratio of actual flow to the full flow as derived based on Manning's Equation, unitless.

21.   Water Depth - The depth of water as it is flowing through the pipe, ft (m).

22.   Critical Depth - The depth of water resulting when the Froude Number is equal to 1.0, ft (m).

23.   Full Flow - The capacity of the pipe as evaluated based on Manning's Equation (when d/D = 1.0), flow units.

24.  Coverage Count - The population parameter used in the Harman and Babbitt equations.

25.   Backwater Adjustment – If the downstream head of the link is greater than the flow depth + the downstream pipe invert then the adjusted depth is one half of the sum of the water surface depth at the upstream and downstream ends of the link.

26.   Adjusted Depth – The adjusted depth is the average of the upstream plus the downstream adjusted depth, where the upstream adjusted depth is the upstream head minus the upstream pipe invert elevation and the downstream adjusted depth is the downstream head minus the downstream pipe invert elevation.  The adjusted depth is the minimum of the pipe diameter and the computed pipe adjusted depth.

27. Adjusted Velocity –  the adjusted depth is used to calculate the wet area and adjusted velocity = flow/wet area. 

InfoSewer Static Loading Manhole Report

Note:  Static Loading Manhole Report

Shows steady state simulation results for all manholes in tabular format. The report displays one record for each manhole in the current H2OMAP Sewer project.  Manhole report columns include the Node Identifier, Rim Elevation, Load, Overload and Grade, surcharge status, occurrence of a hydraulic jump across the node and the unfilled and surcharged depth.

The following variables are displayed on the Static Loading Manhole Report in the Output Report Manager for all or selected manholes:

1.      ID - Manhole node identifier.

2.      Rim Elevation - Manhole node elevation, ft (m).

3.      Base Flow - The base loading applied to the manhole (before peaking), flow units.

4.      Total Flow - The calculated flow (after peaking), inserted into the manhole, flow units.

5.      Storm Flow - Peak storm load at the manhole, flow units

6.      Grade - Manhole node hydraulic grade for the steady state simulation, ft (m).

7.      Status - Surcharge status of the manhole.

8.      Hydraulic Jump – Was there a Hydraulic Jump between the incoming and outgoing pipe of the node?

9.      Unfilled Depth – depth between the node Rim Elevation and the Node Grade.  A zero value indicates it is full.

10.  Surcharge Depth - is the difference of “The Depth of Water of Manhole” and “The Crown of the Highest Connecting Conduits”.  A positive Surcharge Depth means the node water surface elevation is above the highest pipe crown, a negative depth means that the node depth is below the highest pipe crown.