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Bentley Systems? water and wastewater modelling applications aim to provide analytical solutions for planning, design and operational intelligence for water and wastewater utilities, explained Gregg Herrin, director for product management, and Cyndi Smith, senior industry marketing director

bentley 29Cyndi Smith is a senior industry marketing director for Bentley Systems? utilities, water and communications industries. (Image source: Bentley Systems)

As water and wastewater networks are inherently geospatial, comprising interconnected assets that are often buried underground, a utility must know the right method to effectively manage them, particularly how the water and wastewater network operates in various conditions to optimise these assets for its customers.

According to Bentley, a geographic information system (GIS) and a hydraulic modelling system (HMS) are at the core of serving these related needs. With regards to this, Bentley said that Esri?s ArcGIS manages all types of geospatial business data including land use and parcel information as well as the locations and basic characteristics of water and wastewater network assets. In addition, Bentley?s HMS applications WaterGEMS or SewerGEMS provide additional hydraulic characteristics for the network elements and offers engineering insight into the complex behaviour that defines network performance.

These two complementary water and wastewater modelling applications seamlessly provide advanced hydraulic modelling capabilities through the ArcGIS platform, enabling the hydraulic modelling and GIS communities to simultaneously build and update network models using data from Esri geodatabases and geometric networks as well as manage hydraulic network model data in an Esri geodatabase.


GIS technology, such as ArcGIS, supports geospatial data management, visualisation, query, analysis and reporting capabilities in a spatial context.

The GIS team in a water utility is typically responsible for keeping the network and its supporting geospatial data up to date and for providing efficient access to the rest of the organisation. One of the most demanding groups in need of this data is the hydraulic modelling team. GIS has evolved in tandem with hydraulic modelling to become an essential capability for the water and wastewater modelling communities as a source of modelling data for spatial analysis and decision support.

Hydraulic modelling

Hydraulic modelling involves the simulation and analysis of water, wastewater and stormwater network systems. It uses mathematical models to solve specific design, planning and operational problems related to capacity, flow, pressure, water quality, energy and other considerations that go beyond the physical characteristics and the geospatial data that GIS technology manages.

The hydraulic modelling team in a water utility or consulting firm comprises specialists in hydraulic or environmental engineering who have extensive knowledge of and experience in modelling for a wide variety of applications including master planning, pump scheduling and water quality analysis.

?GIS technology and geospatial data play a significant role in any successful hydraulic modelling effort, supplying planners and operators with more reliable geospatial inputs into these modelling processes,? Bentley noted.

Planners, engineers and technicians have access to more reliable, concurrent information and the integration of GIS with hydraulic modelling enables water utilities to maximise the value of their investments in both systems. This translates to tangible and measurable value to the business when evaluating capacity and supply deficiencies, avoiding sanitary and combined overflows, detecting and locating leaks, optimising energy utilisation and lowering electricity costs, among other improvements.

The need for model management

Bentley described that the hydraulic modelling requires accurate and up-to-date information to represent existing network condition and status, but constructing and maintaining a hydraulic model over time can be time-consuming, costly and error-prone. Network data held in the geospatial database is maintained on an ongoing basis, making frequent updates to reflect the ?as-operated? state of the system.

?Before the integration with GIS technology, the process of building, calibrating and maintaining the model was a specialised task, carried out independent of the utility?s routine business procedures and workflows. Gathering and digitising data from a wide variety of sources was a manual process that often resulted in inaccuracies,? Bentley noted.

?In response, hydraulic modelling software vendors developed capabilities that enable the modelling community to construct and maintain network models more efficiently and accurately from an increasing volume, variety and velocity of sources so that utilities can build and maintain precise models efficaciously,? the company further added.

GIS for model management

A GIS that supports a hydraulic model requires a high level of data quality, accuracy and detail. This involves developing a network data model, schema, and meta-model in the GIS that supports the hydraulic model creation and updates, including all physical assets to be modelled, the attribution required by the modelling system, and, most critically, network connectivity.

For general mapping purposes, pipe ends only need to visually appear close together, but not necessarily be topologically connected in the GIS. This isn?t sufficient for hydraulic modelling systems, though, as accurate connection information is crucial in recognising how water will or will not flow between pipes. Modelling systems, therefore, provide capabilities that look for topological errors in the GIS database and assist in manually or automatically fixing these errors.

In the past, a network model was typically built as a ?snapshot? of the geospatial database and only updated intermittently. Now, models can be updated more frequently because GIS and hydraulic modelling teams can leverage the most appropriate capability from either the GIS or the hydraulic model.

?Additionally, GIS manages large volumes and increases the velocity of updates, and they automate the model building process, making it faster and more efficient. With the GIS community maintaining an appropriately constructed geospatial database of network elements, the hydraulic modellers can spend more time running simulations and carrying out engineering analyses to evaluate the performance of their water and wastewater systems,? Bentley explained.

Technology flexibility ? GIS, CAD or both

A versatile, multi-platform environment liberates users from a specific platform, allowing modellers to share a single modelling dataset derived from any major CAD vendor or from ArcGIS. This enables the modellers to use and open the same model file in any of the supported CAD or GIS applications.

?Bentley Systems provides the flexibility to carry out hydraulic modelling projects using a GIS-agnostic platform using WaterGEMS or SewerGEMS through a standalone geospatial interface or through alternative GIS/CAD platforms such as MicroStation and AutoCAD. This allows Bentley users to leverage a common modelling application and connected data environment shared across these platforms, with the same model, data and functionality, regardless of platform,? the company concluded.