• Determine the purpose of your model--Once you establish the purpose of your model, you can start to make decisions about how detailed the model should be.
• Get familiar with your data--If you obtained your GIS data from an outside source, you should take the time to get acquainted with it. Review spatial and attribute data directly in your GIS environment. Do the nodes have coordinate information, and do the pipes have start and stop nodes specified? If not, the best method of specifying network connectivity must be determined.
• Contact those involved in the development of the GIS to learn more about the GIS tables and associated attributes. Find out the purpose of any fields that may be of interest, ensure that data is of an acceptable accuracy, and determine units associated with fields containing numeric data.
• Ideally, there will be one GIS source data table for each Drainage and Utilities element type. This isn’t always the case, and there are two other possible scenarios:
  1. Many GIS tables for one element type--In this case, there may be several tables in the GIS/database corresponding to a single modeling element . In this case each data source table must be individually mapped to the Drainage and Utilities element, or the tables must be combined into a single table in the GIS/database before running ModelBuilder.
  2. One GIS table containing many element types--In this case, there may be entries that correspond to several Drainage and Utilities modeling elements in one GIS/database table. You should separate these into individual tables before running ModelBuilder. The one case where a single table can work is when the features in the table are ArcGIS subtypes. ModelBuilder handles these subtypes by treating them as separate tables when setting up mappings. See Subtypes for more information. If you are working with an ArcGIS data source, see Esri ArcGIS Geodatabase Support for additional information.
• Preparing your data--When using ModelBuilder to get data from your GIS into your model, you will be associating rows in your GIS to elements in Drainage and Utilities. Your data source needs to contain a Key/Label field that can be used to uniquely identify every element in your model. The data source tables should have identifying column labels, or ModelBuilder will interpret the first row of data in the table as the column labels. Be sure data is in a format suited for use in ModelBuilder. Use powerful GIS and Database tools to perform Database Joins, Spatial Joins, and Update Joins to get data into the appropriate table, and in the desired format.

One area of difficulty in building a model from GIS data is the fact that unless the GIS was created solely to support modeling, it most likely contains much more detailed information than is needed for modeling. This is especially true with regard to the number of piping elements. It is not uncommon for the GIS to include every service line and hydrant lateral. Such information is not needed for most modeling applications and should be removed to improve model run time, reduce file size, and save costs.