Advanced Modelling for Leakage Assessments, Planning and Operations

Modeling for Leakage

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February 11, 2021

Utilities are spending large amounts of money on Non-Revenue Water and hours developing annual water loss reports with little way of tracking this through the year or how it can be dealt with. As a result, leakage strategies are being picked up by utilities all over the world to meet targets of leakage reduction through the network, both transmission and distribution. Leakage management means different things for different countries, utilities, departments which means different aspects of a strategy will be required.

Broadly speaking, a leakage strategy encompasses all parts of the business at different levels and can be broken into these 3 key areas;

1. Strategic Overview,
2. Zonal Planning
3. Operations

Let’s discuss these.

Creating a Strategic Overview

In order to review an assessment of current levels for the full network of a potable water distribution, you need to be able to quantify the leakage and where the greatest areas are. This is widely done using Infrastructure Leakage Index (ILI), mass balance and minimum nightly flows to estimate background leakage from available flow and pressure data. These calculations when done on each area, can enable a systematic approach for reducing water loss.

By proactively managing and preforming calculations on a frequent basis, leakage and target areas can be assessed and a project programme can therefore be developed. In addition to using Innovyze’s Info360 platform, an operational analytical platform can simultaneously be creating reporting and assessments in near real-time.

Hydraulic modelling can leverage such assessments with the enhancement of more detailed network results and analysis. Innovyze’s hydraulic modelling platform, InfoWorks WS Pro, allows connection of field telemetry data to be linked to assets within the model. This allows a comparison of modelled expected data and live data in a geographical platform.

The connection of this data enables applications within the software such as Leakage locator, which can help identify an area of the suspected new leak. The approximate magnitude of the leak must be known, then by comparing simulated and observed pressures at monitored locations, the leakage locator simulations can then be used to narrow down the area in which the leak is most likely to be located.

Figure: Output from the analysis of Leakage Locator in InfoWorks WS Pro with area in red showing likely location of leak.

The demand assessments can also give an indication of the volume of excess to non-revenue water and so then the volume that can be reduced in each area. Demand Area Analysis function in InfoWorks WS Pro, provides a deep analysis on the water consumed within each DMA and consequently. This allows all water supply areas to have the background losses/ expected leakage calculated using the customers and mains length.

The total non-revenue water is then calculated, as well as the calculation of the excess water that is unaccounted for in each area. This will help identify the areas where leakage can be reduced the most and which areas can be tackled to achieve targets the quickest. Leakage reduction can then be achieved by prioritising rehabilitation or pressure management taking into consideration the leakage rate in each DMA.

Figure: Output of a DMA analysis for the excess unaccounted-for water and therefore the amount of leakage reduction available.

Developing Zonal Planning and Resiliency

Zonal planning and resilience can be a key factor in reducing leakage, yet often overlooked. For example, using this management technique will allow for a better understanding of the full holistic network and therefore investment can be targeted to areas that ensure the greatest leakage reductions.

Zonal planning can also benefit site surveys where there are questions over network configuration and deploying more live data sensors to capture data that can be assessed for leakage levels. Helping users in narrowing down their analysis and start evaluating leakage rates in different branches with the same DMA.
Hydraulic modelling can provide assessment of critical network pipes which are the most at risk for affecting large populations. This process helps to direct projects to ensure resilience if there is a burst to look at other valving options. Having the capability to assess these critical pipes and simulate the effects on the network is a great advantage of hydraulic modelling.

Pipe break analysis means you can replicate leaks and bursts on pipes of differing size (diameter and volume). Subsequently this will enable you to monitor the supply and pressure customers will achieve. By replicating current leaks that are found, the volume of water loss can be calculated and can help with reporting towards reduction goals.

In addition, asset management tools such as InfoAsset Planner, allows operators and managers to evaluate the structural conditions of their networks by conducting risk and reliability analysis based on likelihood and consequence of failures. Also, assists in developing optimised rehabilitation and maintenance plans taking into consideration the Life Cycle Cost Analysis.

Hydraulic and structural conditions combined to the criticality of failure for each element within the network allow a much better planning and a more efficient pressure management and consequently a leakage reduction.

Pressure management is a global network design method to reduce leakage in specific areas of the network with pressure reducing or sustaining valves. These can be modelled using the inbuilt valves and valve curves within InfoWorks WS Pro in order to achieve the optimal location, pressure and design for the network.

Pressure can be varying throughout the day and can be configured to maintain pressure based on a point within the network (most commonly critical point). A project with Innovyze, Optimatics, Stantec and Thames Water enabled pressure management optimisation options (i.e. trying various combinations of pressure, settings and pump curves) in the Hammersmith area of London to have a benefit leakage of £2.9 million.

Innovyze’s proprietary engines allows for the accurate modelling of these planning exercises for the full network. Simulation parameters such as drain down, recharge and pressure related demand functionality allows the system to use demand and pressure in the system to represent a more accurate result. Whereas, other modelling packages, as soon as there is an isolated area, results show no pressure and supply instantly, this isn’t realistic and can generate inaccurate results.

Innovyze’s water distribution modelling software allows these assessments to be carried out quickly and on the whole network due to unique functionality enabling simulations to be performed on remote computers and in parallel.

Operation: Isolate and Fix

As the programs and plan generated from some of the points above the operations team are used to isolate and fix that leak. There is a range of technology on the market to find the exact location of background leaks including acoustics when assessments, as discussed above have found the general area of high priority and biggest benefit.

Moving forward though there should be continuous monitoring of assets and leakage to ensure that low leakage levels don’t increase. Leveraging the power of hydraulic modelling, operations teams can connect telemetry/SCADA systems with demand forecasting to run forecasts of the network behaviour into the coming hours and days.
User defined warnings and alerts are generated to identify operational problems in real-time to understand the best outcome before the problem occurs or if a leakage plan was being implemented on the network.

Figure: Operationl Modelling interfce, showing customer effected and graph of predicted model results against live data

Models also allow for emergency planning to be tested in advance, a large burst, main failure or isolation may require valve settings to be overwritten, pump configurations to change. These can all be tested in a hydraulic model and a process compiled to ensure this is done as efficiently as possible with minimal affect and customer service is maintained.

For better solutions for your leakage issues visit: InfoWorks WS Pro, IWLive Pro, Info360 and InfoAsset Planner