Water & Wastewater Asia Nov/Dec 2018

Water & Wastewater Asia • November / December 2018 24 | FROM THE GROUND Hydraul ic model l ing for Esri © ArcGIS users This is the second of a two-part series whereby Bentley Systems shows how modellers of water and wastewater systems and GIS professionals can leverage enterprise Esri geospatial data repositories and ArcGIS technology in an immersive single modelling application. By Gregg Herrin, Director, Product Management; and Cyndi Smith, Senior Industry Marketing Director 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, combining, and digitising data from a wide variety of sources was a manual process that often resulted in inefficiencies and inaccuracies. In response, hydraulic modelling software vendors have 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 modeled, 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 updatedmore frequently because GIS and hydraulic modelling teams