Hydraulic modelling for Esri ArcGIS users

WATER AND wastewater networks are inherently geospatial, comprising interconnected assets that are often buried underground. To effectively manage these assets, a utility must know what they are, where they are located, and how they are connected both physically and functionally. A utility must also know how their water and wastewater networks operate in various conditions to optimise these assets for its customers.

Two systems are at the core of serving these related needs. A geographic information system (GIS), such as 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. A hydraulic modelling system (HMS), such as Bentley Systems’ hydraulic modelling applications WaterGEMS or SewerGEMS, provides additional hydraulic characteristics for the network elements and offers engineering insight into the complex behaviour that defines network performance.

These two complementary technologies offer analytical solutions for planning, design, and operational intelligence for water and wastewater utilities. Water and wastewater modelling applications can seamlessly provide advanced hydraulic modelling capabilities through the ArcGIS platform that is familiar to Esri users.

The applications can take advantage of any geospatial data managed in Esri’s geodatabases and shapefile formats. This capability enables 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.

GEOGRAPHIC INFORMATION SYSTEMS

GIS evolved from a modest beginning, in which it provided a digital map of network assets. This is a key service in delivering enterprise spatial data and advanced capabilities that allow a water or wastewater utility to better manage, operate, and maintain critical infrastructure. GIS technology, such as ArcGIS, supports geospatial data management, visualization, 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. In fact, 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, so hydraulic modelers have unavoidably become GIS “savvy.”

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 integration has also fostered closer working relationships between the hydraulic modelling and GIS communities, each gaining a better understanding of the requirements of the other, resulting in value through data interoperability.

THE NEED FOR MODEL MANAGEMENT

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. 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.

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 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. This is a prime example of how the hydraulic modelling community can increase the value of the geospatial data through validation, improvements in accuracy, and additional information.

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 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 modelers can spend more time running simulations and carrying out engineering analyses to evaluate the performance of their water and wastewater systems.

TECHNOLOGY FLEXIBILITY – GIS, CAD, OR BOTH

A versatile, multi- platform environment liberates users from a specific platform, allowing modelers to share a single modelling dataset derived from any major CAD vendor or from ArcGIS. This means that modelers can use and open the same model file in any of the supported CAD or GIS applications. For Esri users, that means working in the ArcGIS ArcMap interface they are most familiar and leveraging the existing geospatial capabilities built into ArcGIS.

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