United Kingdom (UK) Features and Workflows in OpenFlows Storm and Sewer Products


Product(s):SewerGEMS, CivilStorm, StormCAD, SewerCAD
Version(s):CONNECT Edition
Area:Modeling

Background

The OpenFlows storm and sewer products include a number of features specific to modeling systems in the United Kingdom or system required to use these methods. This wiki will provide information on these features and workflows. Additional information on these features can also be found in the Help documentation (File > Help).

Features and Workflows

Storm Data

The following rainfall methods are available in the Storm Data manager (File > Storm Data > Storm Data or Components > Storm Data > Storm Data).

Flood Estimation Handbook 1999 and 2013

The Flood Estimation Handbook retains the FSR rainfall profile and Areal Reduction Factor considerations utilized in the calculation of runoff rates according to the FEH of rainfall runoff methods. The ability to import FEH 2013 data was implemented in the CONNECT Edition Update 3 release of the Storm-Sewer products.

To use this method, create a new entry for the Flood Estimation Handbook storm type. You will then be able to import an XML file that is available from the UK Centre of Ecology & Hydrology through their FEH Web Service. After importing this, the depth is calculated from the file details, and then converted to intensity-based rainfall series.

This link has details on this method: Using Flood Estimation Handbook 2013 storm data in storm-sewer products.

Flood Studies Report

With the Flood Studies Report, you would enter the UK Standard Location, the rainfall depth value (R in the screenshot below), and the expected depth of rainfall in millimeters from a storm lasting 60 minutes with a return period of 5 years. Note: If your units are not in mm, you can right-click on the unit and choose Units and Formatting to change the units.

UK Storm Profiles (Dimensionless rainfall curve)

Using Time-Depth or Time-Intensity storm types, you can import the UK Storm Profiles dimensionless rainfall curve. After creating a new Time-Depth or Time-Intensity storm, click the “Add Return Events” button and choose “Add Return Event from Dimensionless Curve”.

This will open the Dimensionless Curve engineering library, where you will be able to choose either the 50% Summer Profile or the 75% Winter Profile.

After selecting the curve, you will enter the return event, depth type (Incremental or Cumulative), depth and duration. After clicking OK, a new curve will be available based on the input.

Whatever storm data type is used, once the storm data is inputted, the storm is assigned to an Rainfall Runoff alternative using Global Storm Events (Home > Storm Data > Global Storm Events or Components > Storm Data > Global Storm Events).

Rainfall Runoff methods and Time of Concentration

Two runoff methods commonly used in the UK are included in SewerGEMS and CivilStorm. The runoff method is set in the catchment properties.

With the Modified Rational (UK) Method, you will define the time of concentration the type of area (Single Area, Multiple Subareas, and Land Use Area). With Multiple Subareas and Land Use Area, you will have a collection field with input for the area.

With Time-Area runoff method, you will define the Time-Area Diagram Type (User-Defined, Linear, and Synthetic Curve (HEC-1). The input parameters in the properties will change based on the input.

For information on the runoff methods available for different solvers, see this link: Runoff Methods supported by each solver. 

Time of Concentration can be added as a user-defined value, but if you select Composite Tc for the “Tc Input Type” field in the catchment properties you can select from a number of calculation methods for time of concentration, including Wallingford (UK).

Critical Storm Analysis

The Critical Storm Analysis feature analyzes the results of the selected scenarios to determine which scenario is the most critical either by using the hydraulic grade results at nodes or the flow results in conduits. For each analysis type, you can choose whether to use the Maximum, Mean, or Median values for hydraulic grade or flow, depending on the method you choose.

To access the Critical Storm Analysis tool, go to the Compute button on the Analysis ribbon. In the drop-down menu, click Critical Storm Analysis. Choose the Analysis Type, select the scenarios to analyze, and click OK.

Detailed information on Critical Storm Analysis can be found at the following link: Using the Critical Storm Analysis feature.

Inlets

There are two UK-specific inlet types in the Inlet Catalog: Kerb and Grating.

The Inlet Catalog is available through the Ribbon search or Components > Catalogs > Inlet Catalog. When you choose the inlet type the input parameters will be available. Once you have the data entered, you will be able to choose the catalog inlet in the catch basin properties.

If you use the Grating inlet type, there are additional parameters that need to be entered in the calculation options. In the Inlets section of the calculation options, click in the Grating Parameters cell to enter the Grating Type and Grating Parameter.

Branch Labeling

With Branch Labeling, you can set the labels of conduits or pressure pipes using the indexes of the branches that the conduits are in and using the indexes of conduits in the branches. The branches used for setting conduit labels are found by searching the longest path from an outfall node or a node in a branch.

To use this feature, use the Ribbon search or go to Tools > More > Branch Labeling.

Details on the input for this can be found in the Help documentation.

Low Impact Development

Low-Impact Development (LID) is a term used mostly in the US and Canada to describe a more eco-friendly land planning and design approach to stormwater management. In the United Kingdom, this approach is referred to sustainable urban drainage systems (SUDS), and in Australia, it's called water-sensitive urban design (WSUD). The US terminology is used in this software and its documentation.

LID controls help developed watersheds or sites to retain or enhance pre-development hydrologic characteristics through the use of techniques that conserve natural systems and hydrologic functions.

More information on Low Impact Development can be found here: Model Low Impact Development (LID) Controls.