Wadiso

Sewsan

Swift

Albion

Introduction

Wadiso 2 Wadiso 3 Wadiso 4 Wadiso 5

Wadiso is a comprehensive computer program for the analysis and optimal design of water distribution networks. The program originated from the WADISO public domain model developed by Prof. Johannes Gessler of Colorado State University for the Army Corps of Engineers. Dr Erik Loubser, studying under the mentorship of Prof. Gessler, assisted with the development of a unique system design optimization module of the program. Subsequently a programming team employed by GLS Engineering Software (Pty.) Ltd., the South African based software development company responsible for development and support of Wadiso in South Africa, substantially improved the basic WADISO with regard to user friendliness and speed as well as interfacing with other application software such as water quality analysis, CAD, GIS and management programs. The improved WADISO was subsequently referred to as WADISO SA. During recent years WADISO SA was taken to a new level by the development of a full 32 bit Windows 2000/XP version. The latest edition is again named Wadiso as the name is now a registered trade mark in South Africa. The following is an overview of the features of Wadiso. The program integrates steady state simulation, time simulation, optimization, and water quality analysis with graphical displays of data and results into a single, most valuable tool for water engineers.

The latest version of Wadiso, offers four modules for the modelling and analysis of a distribution system. Wadiso now includes a seamless interface to the public domain EPANet program module for all modelling aspects.

• Steady State Analysis Module: This is the basic module which allows for the input and editing of system data and parameters, and which calculates the flow and pressure distribution in the system under specific "snapshot" steady state conditions. Full graphical display of flows, pressures, etc. is available.
• Extended Period Simulation Module: This module allows for modelling of diurnal fluctuations in water demand, and controls of pumps, valves, etc. in order to monitor system performance (e.g. tank level fluctuations, pumping cycles, pressure variations) over an extended period of time.
• Optimization Module: This unique module allows for the determination of future improvement needs, with the objective being to minimize capital expenditure and present worth of operational costs, while adhering to specified operational criteria. The cost trade-off between pipes and pumping costs, and pipes and storage cost are taken into account for the optimization.
• Water Quality Modelling. The embedded EPANet program module provides an array of water quality modelling features accessible from Wadiso.

The Wadiso concepts, both with respect to speed and robustness of the balancing algorithm and cost benefits of the optimization technique, are well known and have been well documented in the literature. The main examples in this regard are:

• Gessler (1984) produces a new benchmark optimum solution with WADISO for the New York Aqueduct Tunnels problem.
• Gessler and WADISO (1985) wins the "Battle of the Network Models" at an ASCE conference in Buffalo NY, producing the most cost-effective solution to the "Anytown, USA" benchmark problem.
• Loubser, B.F. (1987), after extending WADISO to include storage costs in the optimization technique, improves the "Anytown, USA" benchmark previously set in Buffalo.
• Sinske, A.N. (1993), rewrites the WADISO tank optimization algorithm to take account of sparse matrix techniques.

Wadiso has been used for distribution system analysis and planning by GLS Consulting and other consultants in more than 100 major applications. Some of the more significant projects are:

Large to medium sized cities for which the distribution systems were modelled in detail, with inclusion of the smallest diameters distribution pipes, are as follows:

• Greater City of Ekurhuleni (Gauteng, South Africa) - total of 600 000 stands serviced
• Greater City of Pretoria (Tshwane) (Bulk and reticulation) - total of 650 000 stands serviced
• Greater City of Cape Town (Bulk and reticulation of most cities) - total of 650 000 stands serviced
• Greater City of Johannesburg (Bulk and reticulation of most cities) - total of 800 000 stands serviced
• Local municipalities of the Western Cape (Bulk and reticulation of most towns)
• City of Windhoek, Namibia (Bulk and reticulation) - total of 100 000 stands serviced
• City of Blantyre, Malawi
• City of Novokuznesk, Russia
• City of Vernon B.C., Canada
• If you have modelled an interesting place using Wadiso we would love to hear from you! Please contact us.

In all the above cases, the existing system and existing demands were modelled and analyzed, prior to an extension of the model to represent future scenarios. The optimization module of Wadiso was typically subsequently used to establish an economically optimal master plan for existing and future improvement needs of each system.

Studies where the extended period time simulation module of Wadiso was used in particular, with a view to optimization of the operation of a bulk distribution system are as follows:

Greater Pretoria: 850 km pipes, 98 tanks, 45 pumping stations, Average Daily Demand of 510 Ml/d.
City of Cape Town: 630 km pipes, 63 tanks, 19 pumping stations, Average Daily Demand of 860 Ml/d.

GIS Compatibility

The open input and output data structures (ASCII, Dbase IV, Paradox, Microsoft MDB) of Wadiso provides for easy interfacing with other application software, including most GIS applications, specifically the ESRI shape file standard and REGIS/Autodesk World FEA format. An interface between the GIS and the Wadiso database typically allows:

• Updating and editing of the model characteristics and parameters
• Updating of water demands, if there is a link between the sales records and the GIS
• Updating reports on the analysis results directly from GIS

Model Characteristics

Wadiso Model Characteristics/Features

• Seamless transition between modules, e.g. Graphics to Steady State to Extended Period Simulation (EPS) to Water Quality Analysis to Optimization.
• Graphical display, input and editing of any network element. Non network data may also be displayed as background, e.g. basemap/stand and street layouts.
• All pipe data required for modelling is included in the database, with extra fields for other attributes.
• The same applies for other links, as well as for nodes and tanks.
• Graphical display of results, through color coding, arrows on pipes, different line thickness, different node sizes, etc., is available.
• Graphical display is always geographically correct, and not schematic. Bitmap images can also be imported as backdrop.

Model Components

The model can include pipes, tanks, pumps, and many types of control valves.

Pumps can be modelled using a parabola fit through three known points on the manufacturer-supplied or calibrated pumping curve or using a series of Heas vs Flow points.

All control valves can be simulated in fully closed, partially open (active) or fully open modes. A pump or valve can be set as closed or off by changing its current state.

Solutions and Optimization Algorithms

In Wadiso, head loss in pipes is calculated by either the Hazen-Williams equation or the Darcy-Weisbach equation where the user has the option to specify an absolute roughness k in which case the f is dependent on Re and is calculated with the appropriate equation.

Numeric Balancing Pressures and Flows

A number of numeric schemes have been proposed and used in the computation of the pressure and flow distribution in pipe networks. Each one has its specific characteristics: some schemes are simple to implement, others require the least amount of computer memory, or the least amount of computer time to find the answer. Again another characteristic is how the program performs under extreme conditions, does it easily "crash" or is it particularly "robust" when analyzing unusual situations, as might be encountered during extended time simulation or during optimization. The technique employed in Wadiso is a node method: the non-linear loss equation for each pipe (or pump) is linearized and substituted into the continuity equation at each node. The result is a system of linear equations with as many equations as there are nodes in the system which is solved through an iterative procedure. The major advantages of this technique include:

• A coefficient matrix which is symmetrical for all systems (even in the presence of pumps and pressure reducing valves).
• A network topology which does not change substantially if during the optimization pipes are removed.
• Excellent convergence characteristics.
• An algorithm which has hydraulic head (or pressures) as the primary unknown, allowing excellent control over required and achieved accuracy.

Optimization Technique

Pipe network optimization is a relatively new field. Nevertheless, a fair number of algorithms have been suggested to perform optimization. But there is no procedure yet which is generally accepted as "the best technique". Optimization of networks is difficult for a number of reasons:

• Pipe sizes are selected from a list of available sizes, that is size is not a continuous variable.
• Cost functions are rather arbitrary and cannot be put easily into a mathematical form.
• When cost for pumping energy is to be included, the pressure distribution in the system must be known.
• The cost function of a looped system as function of pipe sizes to be selected may have several local minimums, yet of interest is only the global minimum.
• Optimization should be carried out for several demand loads so that pressure requirements which may differ from load to load can be met simultaneously.

In Wadiso a relatively straightforward algorithm is employed based on "exhaustive enumeration". The user specifies the sizes to be considered for each pipe and the program simply tests all possible combinations of pipe sizes to check whether the specified pressure constraints are met. In the process of testing the technique takes advantage of two considerations: after a functional combination of pipe sizes has been found there is no need to test any other pipe size combination which is more expensive and after a non-functional solution has been encountered any other size combination, with all sizes equal or less than in the non-functional solution, is non-functional as well. (There are some exceptions to this rule which Wadiso takes into account.) As a result of considering those two aspects Wadiso does not need to calculate a flow and pressure distribution for all combinations. Indeed the larger the total number of combinations the smaller the percentage of combinations for which the pressure distribution needs to be calculated. It is not unusual for Wadiso to test less than one percent of all possible combinations for pressure. The program also takes advantage of the convergence characteristics of the numeric method mentioned in the previous paragraph. If pressure needs to be calculated the algorithm may quickly (in two or three iterations) determine that a combination will or will not work. Only in very few combinations will it be necessary to calculate pressure distribution to a high degree of accuracy.

Exhaustive enumeration has one more important advantage: it allows for the establishment of a queue of "Pareto Optimal" solutions, that is solutions which may cost a little bit more than the optimum solution yet provide for better pressure, or solutions which may slightly violate the pressure requirement but do offer some savings. In other words the user gets immediate feedback on the sensitivity of the optimum to the specified pressure requirements. It is this queue of Pareto Optimal solutions which many users of Wadiso find to be of particular value.

Water Quality Modelling

The EPANet program, which is included as a module in Wadiso, provides a comprehensive analysis of water quality aspects in a distribution system.

SCADA Link

Interfacing between SCADA and the software provided can occur on a dynamic basis. In such an interface metered flows, pressures, tank levels, pump and valve status etc. are converted to relevant parameters and variables which are imported to update the data input files of the simulations and analysis models. The open input and output data structure of Wadiso allows for easy interfacing in this regard.

Results Presentation

Wadiso provides for an extremely flexible query system in order to map data and results. For both nodes and links additional data can be included in user-fields. This allows for the inclusion of information pertaining to age, material and pressure classifications etc. of pipes, present and future allocation of stand numbers etc. to nodes, over and above the normally required data defining the component.

A link and node legend is provided, in which the color coding parameters for any one of the link or node data fields can be specified, if a map is to be produced showing output data such as the flow velocities or energy gradients in the pipes, or residual pressure at nodes, with different color coding and different line widths.

In graphical display it is possible to turn on and off either the node display, so that only pipes are mapped, or the pipe display so that only nodes are mapped.

Text from the different fields can also be annotated to the nodes and links. Specify fields can be selectively annotated, e.g. the link # and pressure, or diameter.

Graphs

In both Wadiso and for the background module of EPANet, graphs can be displayed for the results of any link or any node, for the entire time period.

Tabular Reports

The presentation of tabular reports is as flexible as that of mapping. Again, specific fields can be selected for both nodes and links, and range categories set, just as in the case of mapping. The difference being that for mapping, only a single field is selected and for tabular reporting all fields, or only the important fields, can be selected.

In the mapping, the line width or node size can be set to zero if a specific category of link or node should not be displayed - in the tabular reports a flag is set in a dialogue box in order to specify whether or not that specific category should appear in the report. This makes it possible, for instance, to print a report on only those pipes with velocities less than 0.3 m/s or more than 1.5m/s, or a report of only those nodes with pressure below 20m.

Hydraulic Gradeline Profiles

User selected routes for profiling can be specified graphically in the Wadiso graphics interface. A profile, display an/or plot showing ground elevation and energy grade line for the route is available from the Steady State Simulation module of Wadiso, as well as for any time period within the Extended Period Simulation module.

History of Changes

13 Dec 2008 Added function to Age System to Value System and new Export to CSV command

05 Dec 2008 Fixed issues with Long Sections: Linetype issue, UCS Issue
05 Dec 2008 Improved Long Sections: New Window, Better Defaults, Apply button, New Selection Mode
02 Dec 2008 Import field from Database: Fixed issue where incorrect user field was updated for links.
02 Dec 2008 F3 (Locate Link/Node) short-cut key now available in all input and result tables
02 Dec 2008 Added F5 short-cut key to system tables to show Filter dialog
02 Dec 2008 Fixed update issue when using filter or select mode in tables and making changes
01 Dec 2008 New Model Topology to Albion GIS and Albion GIS to Model Topology functions
27 Nov 2008 Fixed issue with exporting of valve symbols to GIS and insufficient array dimensioning
27 Nov 2008 Active layer now retained after refreshing system display
27 Nov 2008 Inconsistent export of EPANET export file resolved on multiple balance with respect to Begin/End Nodes
15 Nov 2008 When exiting tables with Filter or Select mode on, the mode is now reset
15 Nov 2008 A bug in Export to EPANET (WaterCAD) with regards to new Memo Fields has been fixed
14 Nov 2008 An hourglass has been added when doing Show Duplicate Nodes
14 Nov 2008 Update of the display of variable length on Quick Draw has been fixed

13 Nov 2008 Floating point exceptions occuring when calling EPANET on some computers now likely resolved
13 Nov 2008 The latest EPANET 2.0012 is now used as balancing engine
12 Nov 2008 Fixed a bug when snapping to existing node and showing proximity circle in quick draw
11 Nov 2008 Fixed a bug in system valuation analysis and also a bug in Link Info Box (Index Error)
10 Nov 2008 Added more cost tables for Wells, Bore holes, River Extractions and Dams
10 Nov 2008 A new system valuation analysis has been added which uses the cost data to calculate system value
05 Nov 2008 Line drawing issue resolved when adding pipe from an existing node and not snapping accurately to the node
05 Nov 2008 Proximity highlight now available when approaching existing nodes in AddPipe with tolerance setting
05 Nov 2008 Increased field length of memo fields when exporting to GIS to 128 characters
05 Nov 2008 The unit display of valves in the Link Info Box is now customized for the specific valve type
31 Oct 2008 Fixed a bug with Import Field From Database and trying to import values into a Memo field of type Integer or Real
06 Oct 2008 All Memo fields now support type Integer and Real. This allows for numeric query and categorization.
30 Sep 2008 Fixed a bug when summarizing Scenario demands in Summary Table
29 Sep 2008 A function to select System Links only has been added under System Selection
29 Sep 2008 Additional cost tables (Tower, Pump, Valves etc) now available for use in future Master Planning functions
16 Sep 2008 Fixed a potential bug when merging WAZ files (out of range table index)
16 Sep 2008 The reporting after merging of models has been improved, also including duplicate links & nodes, mismatching fields
11 Sep 2008 Changed menu: DTM & Cost Data now own main entries in menu
10 Sep 2008 New icon in menu: Access to Valve Table
09 Sep 2008 Inserting a node or splitting a link does not change the auto numbering scheme any more
08 Sep 2008 Highlight of Selected Links & Nodes function added
08 Sep 2008 Select Sequence now extended with separate function: New & Add/Remove of Link&Connected Nodes
05 Sep 2008 The default file format when saving a new model has now been changed to WAZ
05 Sep 2008 A warning has been added when attempting to close a Check Valve as it is not allowed in EPANET
05 Sep 2008 A new Quick Draw Function has been added to the Add Pipe function
05 Sep 2008 System Display Settings are now applied before adding the very first pipe
05 Sep 2008 Text fields can now be deleted by blanking them in Link Info Box (e.g. Scenario, User, Memo)
05 Sep 2008 Pipe diameter is now no longer lost when changing from Pipe to Valve or vice versa in Link Info Box
05 Sep 2008 Table headings are now consistently exported as first row for all tables when exporting to Excel
05 Sep 2008 New tab on Summary Table showing information on Scenario Fields added
27 Aug 2008 Do not show status result when balance has been OK and scroll down to last page of results
27 Aug 2008 Fixed bug on exiting the program and saying cancel at last point
27 Aug 2008 Added function to insert node on crossing of links command (1m tolerance)
27 Aug 2008 Fixed issue with showing System Balanced, when not the case
13 Aug 2008 Added new generic graphing component - for internal use at this stage

24 Jun 2008 Import Field from Database now allows adding/concatenation of data
24 Jun 2008 Now procedure now available to allocate demands using GIS to model - also wrote documentation
20 Apr 2008 Fill/Add operation in Tables on Memo fields now supported
20 Apr 2008 Merging of WAZ and WAF files now fully supported
10 Apr 2008 Added export of point shapes as part of custom export for links (with rotation field)

11 Mar 2008 Added import text to User field for Pumps & Tanks in addition to Pipes & Nodes (located under Help/Beta)