Hydraulic Model Software

[Anais Wachowski]

Hydraulicmodeling is a process in which a pipe network is modeled using physical attributes and equations. The network can be any type of network that transfers liquid or gas in pipes or open channels. In a hydraulic model, the medium is transferred via pressure difference or gravity in the network. In this article, mainly pressurized water networks are handled. Pressure difference transfers the medium according to the path of lowest resistance. Hydraulic models are used to study and analyze system behavior now and in the near future. In the below picture, a simple hydraulic model is depicted.

In a hydraulic model, all the components are converted into digital forms of points and lines. Typically pipes, pumps, and valves are line types of components that have a start point and an endpoint. Consumers, water towers, and water sources are depicted as point components. All the point and line components have x,y,z information so they can be placed over any common map type.

In hydraulic models, there is one component that you cannot find in real networks that is a node or junction component. It is an imaginary component that is in the end and beginning of every pipeline. Junctions are needed to solve the mathematical graph model of system flows. Graph models used in hydraulic models are deterministic, meaning that they yield the same results with the same input parameters. In the below pictures, there are a few results depicted: minimum pressures for junctions and maximum flows for pipes.

Building a hydraulic model can be time-consuming and tedious work if it is done for the first time. The first and foremost information to add to the model is network information. Typically the information resides in a network information system or GIS system. There you can usually find the following things:

A very important thing to understand about network data is, that all the pipes must have data model connections to each other. In other words, all the pipes must know the pipe before and pipe after. There cannot be pipes dangling without connection to nearby pipes. There are automatic methods to enhance the network data if you suspect it to be poor quality.

The next important system to dig information into the hydraulic model is the customer information system. This information can also be in the network information system or the GIS system. The following information is needed from customers to be input into the hydraulic model:

The driving force in hydraulic models, especially water and district energy models, are pumps, controls, tanks, and other operational units. They bring life into the model by moving the medium in the pipelines. The key software component in understanding how any specific network system works is the SCADA(Supervisory control and data acquisition). SCADA systems can be very complex depending on the system size. In a typical medium-sized (200 000 Inhabitat) network you would find dozens of pumping stations, a handful of water towers, and water sources. Digging into the SCADA system and its history database can be the most time-consuming phase of model building. From the SCADA system we need to find out the following data:

For the control parameters, we need to figure out whether the pumpings are pressure or flow-controlled or do we have some type of flow-compensated pressure control or vice-versa. The simplest control for a pumping station would be fixed pressure or fixed flow setting, but there will most certainly be more complex controls in place as well. If there are free-floating water towers in the system, the pumps have also shutdown limits due to water tower levels. Another important aspect that we can get out of the SCADA is flow and pressure history data. All the networks have a small amount of leakage and we can use the history data to calculate base leakage to areas when we know all the inputs, the water consumption, and all the outputs of the area. We can also use the history data to model the water consumption pattern for each area. Typical water consumption patterns look like the picture below:

This page provides a list of nationally and locally accepted hydraulic models that meet National Flood Insurance Program (NFIP) requirements for flood hazard mapping activities. This page is intended for engineers, surveyors, floodplain managers and FEMA mapping partners.

Please reference the following memorandums on the use of HEC-RAS for NFIP purposes. Note that the memorandums are periodically updated and should be read each time before referring to the below chart.

cHECk-RAS is a program designed to verify the validity of an assortment of parameters found in the U.S. Army Corps of Engineers (USACE) HEC-RAS hydraulic modeling program. cHECk-RAS utilizes information generated by HEC-RAS (all versions through the latest version, 4.1.0.) This program can run only on computers with Microsoft Windows XP, Vista, or 7 (32- or 64-bit) operating systems. The current version of cHECk-RAS in use is 2.0.1.

The River Analysis System is able to model spatially and time varying precipitation and infiltration to 2D flow Areas, Storage areas, and between 1D cross sections. Three infiltration methods are available; Initial and Constant Loss method and the SCS method, and Green and Ampt method.

The River Analysis System is able to model excess precipitation applied directly to a 2D flow area. Losses and infiltration are not currently able to be computed within RAS, so excess precipitation should be determined using separate approved hydrologic methods or software (such as HEC-HMS) prior to applying it within the model domain.

Intended for use in areas studied by approximate methods (Zone A) only. May be used to develop water-surface elevations at one cross section or a series of cross sections. May not be used to develop a floodway.

Windows version of WSPG. Computes water-surface profiles and pressure gradients for open channels and closed conduits. Can analyze multiple parallel pipes. Road overtopping cannot be computed. Open channels are analyzed using the standard step method but roughness coefficient cannot vary across the channel. Overbank analyses cannot be done. Multiple parallel pipe analysis assumes equal distribution between pipes so pipes must be of similar material, geometry, slope, and inlet configuration. Floodway function is not available.

Model must be calibrated to observe flows, or discharge per unit area must be shown to be reasonable in comparison to nearby gage data, regression equations or other accepted standards for 1% annual chance events.

The FEQ model is a computer program for the solution of full, dynamic equations of motion for one-dimensional unsteady flow in open channels and control structures. The hydraulic characteristics for the floodplain (including the channel, overbanks, and all control structures affecting the movement of flow) are computed by its companion program FEQUTL and used by the FEQ program.

Includes all the features of DAMBRK and DWOPER plus additional capabilities. It is a computer program for the solution of the fully dynamic equations of motion for one-dimensional flow in open channels and control structures. Floodway concept formulation is unavailable.

Calibration to actual flood events required.

This model has the capability to model sediment transport. Program is supported by NWS.

National Weather Service FLDWAV Computer Program

Hydrodynamic model for the solution of the fully dynamic equations of motion for one-dimensional flow in open channels and two-dimensional flow in the floodplain. Bridge or culvert computations must be accomplished external to FLO-2D using methodologies or models accepted for NFIP usage.

Please review 'Guidance for Flood Risk Analysis and Mapping for Alluvial Fans' thoroughly before applying to alluvial fans. Coordination with the Regional office is required. Calibration to actual flood events is required.

The model must be calibrated to observed flow and stage records or high-water marks of actual flood events at both channel and floodplain. Floodway concept formulation unavailable; however, version 3 allows users to specify encroachment stations to cut off the cross section.

A dynamic coupling of MIKE 11/ MIKE HYDRO River (one-dimensional) and MIKE 21 (two-dimensional) models. Solves the fully dynamic equations of motion for one- and two-dimensional flow in open channels, riverine flood plains, alluvial fans and in costal zones. This allows for embedding of sub-grid features as 1-D links within a 2-D modeling domain. Examples of sub-grid features could include small channels, culverts, weirs, gates, bridges and other control structures.

Please review 'Guidance for Flood Risk Analysis and Mapping for Floodway Analysis and Mapping' thoroughly before applying to floodway analysis. Coordination with the Regional office is required.

The model must be calibrated to observed flow and stage records or high-water marks of actual flood events at both channel and floodplain.

Hydrodynamic model for the solution of the fully dynamic equations of motion for one-dimensional flow in open channels and control structures. The floodplain can be modeled separately from the main channel.

The model must be calibrated to observed flow and stage records or high-water marks of actual flood events at both channel and floodplain. Comparison of bridge and culvert modeling to other numerical models reveals significant differences in results; these differences may be investigated in the near future. Floodway option is not accepted for NFIP usage.

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