Storm Water module in MiTS 3 has 2 modes, Design and Analysis. These 2 modes of analysis can be switched by clicking their respective button, Design/Analysis mode in the Analysis section.

General Input #

Inflow Source #

In MiTS 3, the user was given the option to choose the project’s Inflow Source, Tabular Flow or Graphic Catchment. Choosing the Tabular Flow will require the user to input the data into User Defined Hydrograph after clicking the Tabular button.

Meanwhile, the Graphic Catchment is the old behaviour of designing catchment for the drainage system. The user may either design the catchment directly in MiTS or import it from the drawing.

Design Mode #

Input #

Design mode is the type of analysis from the previous version, MiTS 2. The project will be analysed as a preliminary design based on the design standard, which is the iteration of the drain sizes and IL (if iterate == Yes). This Design mode does not utilize routing and is based on a straightforward, static manning equation. As a result, it is incapable of recognizing time-varying inputs and will always provide a constant output for variables like flow, velocity and water depth.

In Design Mode, Iteration can be used for analysis

To analyse the output, the Analysis Type should be Design in the Storm Analysis Options dialog box. Click the Execute button to open this box and choose the Inflow Source; CatchmentHydrology or UserDefined.

Output #

Sample Project File HERE

As the Design mode is the default analysis mode in MiTS 2, the output is similar to what was analysed in MiTS 2: Excel Report, KeyPlan, Long Section, QS, Textual Report and Sump Detail. There are another 2 Output, Summary and Graph which will be enable for Analysis mode output.

Analysis Mode #

Input #

In the event that users change to the Analysis mode, the project will be analysed in a time series format. This means that the analysis of the drain and storage system will generate a series of flow, discharge and water depth every n seconds. As this Analysis mode is a simulation of the stormwater in a real-life situation, all drain ILs and dimensions are based on the user’s judgement, which means no iteration from MiTS. (User may use Design mode first to get the best possible drain IL and dimension from iteration)

Node as storage #

By opting for Analysis Mode, users can set the node as the typical node (sumps) or storage (representing the pond).

Go to

Node > Spread Input > Storage Settings

By default, the node will be set as a Normal Node. To set it as a storage, click on the ‘…’ button to call out the Node and Storage Configuration Dialog.

Storage Type	Description
Normal Node	Acts like a typical sump, connecting the drains or pipes in a network
Terminal Node	Typically located at the end of a network, near to a water body. Users have the options between Free Outfall, Normal Outfall, and Fix Outfall.
Platform Pond	The node is attached to the pond platform defined in the Earthworks module, whereby the pond level will be read based on the platform level.
Simple Pond	Users will need to define the storage shapes and parameters such as Top Width, Top Length, Height, and Slope X/Y.

Drain Link Type #

In Analysis Mode, the drain can be set as Normal drain, Orifice, and Weir.

Go to

Drain > Spread Input > Link Type

By default, the link type is set as Normal Drain (Normal Conduit). Users can click on the ‘…’ button to call out the Configure Link Type.

Link Type	Description
Normal Drain	Typical drain conveying the runoffs through a systematic network
Orifice	Typically located after a pond, selecting orifice will apply the orifice coefficient (Cd) in the discharge computation.
Weir	Also located after a pond, whereby users can set the weir coefficient and weir type to be applied in their analysis.

Storm Analysis Options dialog #

Set Analysis Type to Analysis and choose Catchment Hydrology or User Defined as the inflow source. With Catchment Hydrology, choose a supported method and configure its applicable settings in Catchment Hydrology Analysis. Configure the hydraulic solver separately in Hydraulic Routing. These settings are also available under Project Settings > Storm Design > Storm Analysis; method-specific pages appear in the tree when their settings apply.

Storm Events #

Click the ‘…‘ button to open the Storm Event Dialog and configure them. Double-click on the default data to adjust them.

Hydrology #

Choose one of the implemented catchment hydrology methods:

• Rational Steady calculates a design peak flow from the runoff coefficient, catchment area, and rainfall intensity.
• Rational Hydrograph generates a hydrograph using Rational runoff assumptions and its storm-duration trials.
• Time Area applies rainfall losses to the storm pattern, then translates rainfall excess through the catchment’s travel-time bands to create runoff hydrographs.

For Time Area, set storm ARIs in Analysis Events and durations in the Time Area duration checklist. The offered durations depend on the selected temporal-pattern region. Flow Proportioning is also in Catchment Hydrology Analysis and assigns runoff from each catchment to the attached drain’s beginning node, end node, or both. Rational methods use Intensity Calculation; Time Area uses event rainfall depth and a temporal pattern.

EPA SWMM catchment runoff is not a selectable hydrology method. The hydraulic routing solver remains a separate setting.

For Time Area catchment bands and loss models, see the Storm Sync Time Area hydrology guide. For graphs, the Catchment Hydrology report, isochrone strips, and EPA SWMM export, see the Storm Sync Time Area Results guide.

Hydraulics #

The Hydraulic Routing group contains the flow-routing method and solver time-step settings. These settings describe how the hydraulic model routes the generated or user-defined inflows through drains, nodes, and storage.

For catchment-generated inflows, configure Flow Proportioning under Catchment Hydrology Analysis. Intensity Calculation is shown for Rational methods only; Time Area uses the event rainfall depth and selected temporal pattern. The routing-method options and their use remain as described below.

Parameters	Options	Description
Flow Routing Method	STEADY	– Simplest routing method (effectively no routing) – Assumes flow is uniform and steady within each time step – Directly translates inflow hydrographs from upstream to downstream without delay or shape change – Uses normal flow equation to link flow rate with flow area or depth – Cannot account for channel storage, backwater effects, entrance/exit losses, flow reversal, or pressurised flow – Suitable only for dendritic networks with single (or two for dividers) outflow links per node – Best for preliminary, long-term continuous simulations; insensitive to time step
	KINWAVE (Kinematic Wave)	– Solves the continuity equation and a simplified momentum equation for each conduit – Assumes the water surface slope equals the conduit slope – Maximum flow is the full normal flow value; excess flow can be lost or ponded at the inlet node and reintroduced as capacity allows – Allows flow and area to vary spatially and temporally, leading to attenuated and delayed outflow hydrographs – Cannot account for backwater effects, entrance/exit losses, flow reversal, or pressurised flow – Limited to dendritic network layouts – Maintains numerical stability with moderately large time steps (1 to 5 minutes) – Effective and efficient for long-term simulations if significant effects are not expected
	XKINWAVE (Extended Kinematic Wave)	– Builds on the basic Kinematic Wave approach – Handles more complex flow scenarios – Models spatial and temporal variations in flow and storage – Offers improved numerical stability and performance – Suitable for detailed analysis when full dynamic wave modelling is too complex or intensive
	DYNWAVE (Dynamic Wave)	– Solves the complete one-dimensional Saint Venant flow equations for accuracy – Includes continuity and momentum equations for conduits and volume continuity at nodes – Can model pressurised flow when conduits are full, with flows exceeding normal values – Handles flooding by ponding excess flow at nodes or losing it from the system – Accounts for channel storage, backwater, entrance/exit losses, flow reversal, and pressurised flow – Suitable for any network layout, including those with diversions and loops – Ideals for systems with significant backwater effects and flow regulation via weirs and orifices – Required small time steps (around 30 seconds or less) for numerical stability, with SWMM adjusting time steps as needed
Routing Steps		The time step of level pool routing

Storage #

There is only one parameter to be inputted which is the storage slice. It is the depth step used to slice the storage for the depth vs area.

Output #

CatchmentHydrology Project File HERE

UserDefined Project File HERE

The only difference between Design mode and Analysis mode output is the Summary and Graph report. The Summary report is where the user can see the Error(s) and Warning(s) within the simulation and the Graph report is a time series graph (e.g.: Flow vs Time).

Some errors that the user might encounter in when using the Analysis mode are as below:

Error Code	Description
Code 113, invalid roughness for Conduit n	Drain’s n roughness (Manning) is either 0 or negative (Inflow Source: UserDefined)
Code 115, adverse slope for Conduit n	Under Steady and Kinematic Wave routing, all drains must have positive slopes. Adverse slopes are permitted under the Dynamic Wave routing
Code 131, the following links form cyclic loops in the drainage system	The Steady and Kinematic Wave flow routing methods cannot be applied to systems where a cyclic loop exists
Code 133, Node n has more than one outlet link	Under Steady or Kinematic Wave flow routing, a junction node can have only a single outlet link
Code 139, Regulator n is the outlet of a non-storage node	Under Steady or Kinematic Wave flow routing, orifices, weirs and outlet links can only be used as outflow links from storage nodes
Code 141, Outfall n has more than 1 inlet link or an outlet link	An outfall node is only permitted to have one link attached to it
Code 145, Drainage systems has no acceptable outlet nodes	Under Dynamic Wave flow routing, there must be at least one node designated as an outfall
Code 173, Time Series n has its data out of sequence	The time values of a time series must be entered in sequential order
Code 227, Transect n has no manning’s N	When the drain n Manning Coefficient is 0 (Inflow Source: CatchmentHydrology)

CatchmentHydrology #

By analysing the project using CatchmentHydrology, the user can choose the suitable routing method based on the project requirement. Each routing method generates its inflow hydrograph.

RationalSteady

A static inflow us used during the analysis, meaning the water flow rate does not change over time, reflecting a constant discharge resulting in a steady flow hydrograph, a simple, flat-line graph.

RationalHydrograph

The hydrograph generated shows the flow rate of water over time, with the peak flow calculated using the Rational method formula, Q = CiA/360 producing a simplified hydrograph shape.

TimeArea

Storm Sync’s Time Area method creates catchment inflow hydrographs from rainfall excess and travel-time bands before hydraulic routing. For catchment bands and loss assumptions, see the Storm Sync Time Area hydrology guide. For result graphs, reports, isochrone strips, and EPA SWMM export, see the Storm Sync Time Area Results guide. This is separate from the legacy PondCAD detention-pond workflow described in the PondCAD benchmark.

UserDefined #

UserDefined which required the user to create a time-series hydrograph plots flow rate against time, providing a detailed view of how discharge in the drainage system varies over a given period.