Sensitivity Analysis with InfoWorks WS Pro

Do we really need complete live models?

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November 6, 2020 | Luca Serena

How critical is the telemetry initialization of your hydraulic model when assessing the impact of an incident?

There is not a unique answer to that question, variations on boundary conditions will have different impacts depending on several variables, such as the amount of storage is available within the network, burst size and duration, incident location, etc.

We could assume that running a model with a small size burst and plenty of storage available won’t cause much difference in results whether you have successfully updated all of your boundary conditions from telemetry or if you have 1 or 2 missing values, with the software that is therefore prompted to use the default setting for that specific parameter.

In this article, we are going to see how we can leverage the InfoWorks WS Pro Generalised Multi Run functionality to perform sensitivity analysis for having or not having a fully updated model. In this sense, we’ll be considering the initial depth value missing for a single reservoir object at a time.

Step 1 – First case: analyze the impact of a 25l/s burst with an initial depth set to 28%, 63%, and 83% percentage full

We can easily implement this scenario using the Generalized Multi-Run wizard:

We are analyzing the impact of an additional 25l/s exceptional flow to node 101021FR (top-right corner) to simulate a 1hr long burst event considering a varying initial depth at service reservoir KRES32 of 1 m (28%), 2.25 m (63%) and 3 m (83%).

The simulation shows the following customers affected by low pressure (min pressure below 15m).

Since our goal is to assess the total number of customers affected, we can introduce the following SQL query to counts and report on number of customers affected by low pressure (less than 15m):

We can drag and drop the query into each result set to read the total number of customers affected for each scenario.

The Generalized Multi Run wizard also allows the user to store the SQL query and use it for automatic result post-processing.

This allows the quick creation of a summary report, which is going to output the total number of customers affected for each test case.

The outcome of this analysis is that by changing the initial depth on service reservoir KRES32 we have some changes in the total number of customers affected by low pressure for a 1-hour long burst of 25l/s at node 101021FR.

Step 2 – Extend the scope to enter the sensitivity analysis

We are now interested in expanding the scope of the assessment to include different burst locations (assuming 20 different points in the network), two event durations (1hr and 6hr), and two burst intensities (25l/s and 50l/s).

We can follow the same process described above, this time we end up with a GMR object that lists 660 test cases to include all of the possible combinations.

Running on a local client with 3 cores allocated for computation, InfoWorks WS Pro will carry out the analysis in 6 minutes and 23 seconds. Results can be copied from the Summary Report over to Excel where a Pivot Table could be used to assess variance.

Only for two out of the five reservoir objects the variation on the initial depth has an impact on the total number of customers affected. This impact is always minimal. A summary of the assessment below.

Conclusion

The importance of having a fully functioning real-time monitoring system is also dependent on the asset location. The hydraulic model provides advanced toolsets to assess the strategic importance of an asset which can then be used to prioritize maintenance work for example or to simply set some redundancy.

InfoWorks WS Pro Generalised Multi Run offers extended computational efficiency for the definition, analysis, and report generation of large-scale network scenarios. Remote agents and Cloud computing are additional tools to extend the ability to perform sensitivity analysis and make full use of your hydraulic models.

Update your software

To update your InfoWorks WS Pro to the latest version, if you have an active InfoCare subscription, just log in to the Product Download section of the Innovyze support portal.

If you are interested in purchasing InfoWorks WS Pro, fill in a product inquiry form or contact us.
For information about InfoWorks WS Pro, visit the product page.

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If you'd like to know more about water distribution products in general, do get in touch or take a look at our Water Distribution Modeling and Management web page.

Tags: water distribution, hydraulic modeling, water modeling, infoworks wspro

About the Authors

Luca Serena

Luca Serena

Product Manager

 

Luca Serena is product manager for Innovyze's Water Distribution product family.