GIS & Hydraulic Modeling

So let’s start with a common question from our W/WW user community – what is the relationship between GIS and hydraulic modeling?

From our perspective, GIS and hydraulic modeling are related through data and workflows.  Most of the GIS data models that water and wastewater utilities use contain many of the same data items that a hydraulic model requires.  This includes features, geometries and attributes.  For example many water utilities use GIS as their system of record to store features of their water distribution system (pipes, valves, pumps, treatment plant, reservoirs, storage tanks, etc) as well as customers locations and past usage, elevations, etc.  Using the example of geometry data for pipes a typical W/WW GIS has location and elevation, so you know where the pipe is, how long it is, it’s elevation and where it connects to other pipes – necessary for a hydraulic model.  Also the pipe has attributes such as installation date, diameter, and material – all of these items are used for a hydraulic model.

Beyond using your geodatabase as input data to build a model, GIS and modeling are also related through workflows.  A change to your GIS, such as adding the water assets of a proposed sub-division to your utility’s proposed water distribution feature classes could kick off a hydraulic modeling activity to determine the impact of the new sub-division on the hydraulic performance of your distribution system.  Another example of the workflow relationship is when hydraulic modelers create a model and uncover an error in the underlying GIS data, for example the wrong diameter on a pipe which caused strange modeling results.  The corresponding workflow should be that the hydraulic modeler makes an edit to the GIS data or passes a redline of the error back to GIS data editors.

Some Esri business partner’s hydraulic modeling packages can directly read a geodatabase to start the process of building a hydraulic model.  By selecting a hydraulic modeling solution from an ESRI business partner you will increase your return on investment in ArcGIS software and GIS data.  Some of these partner solutions work directly in ArcMap, which gives you a seamless workflow between GIS and modeling. To find our partners with hydraulic modeling solutions go to http://www.esri.com/partners/apps/search/?fuseaction=search and search for Solutions with the keyword “hydraulic”.

Once the model is completed, many utilities bring data from the model back into GIS for visualization and further analysis. For example, in ArcMap you could create a map that shows hydraulic problems in your distribution system overlaid on your water assets along with a layer of proposed capital projects from your CIP. Doing this allows you to understand where you need to address hydraulic deficiencies that are not part of a proposed capital project.  Better yet, you could do some GIS analysis in conjunction with your model results – such as generating a report of customers that have complained about their water service of over the past year and have hydraulic issues upstream of them.

Beyond this general discussion there are additional nuances when integrating GIS with hydraulic modeling. For example – how often do you update your model, how do you keep track of changes to the GIS that would cause a change in the model, the benefits of an all pipe model versus skeletonizing, where do you store data such as pump curves & C factors? ESRI, our water/wastewater user community and a number of our business partners are currently collaborating on a white paper to explore these topics.

Have any thoughts on GIS and hydraulic modeling? Please comment on this post or send us an email at: ArcGISTeamWater@esri.com