Synchronization, integration, unification
Software documentation specialist, Joshua Belz outlines the benefits of WaterGEMS from Haestad Methods Inc.
The ability of GIS software to quickly generate a limitless variety of custom
maps suited to numerous applications, along with its powerful data management
and querying capabilities, perfectly complements the modeling, calculation,
and scenario management capabilities of water resource modeling software.
The minimal functionality required for any type of compatibility between modeling
software and GIS is a method of data transfer between the two, and shapefiles
can provide this method.
Using shapefiles to transfer data between GIS and modeling software provides
significant advantages over simply using database files. Since geometric data
is stored in the shapefile, specifying coordinate data is unnecessary. In addition,
shapefiles are a native file format of GIS applications, so viewing and editing
the network within the GIS application is easy and convenient.
However, there are a number of drawbacks involved in using shapefiles to exchange
data between the platforms. One disadvantage is that, just as with a simple
database file transfer, this process involves data replication. Every time changes
are made to data in one application, the shapefile must be exported and reimported
into the other application in order to synchronize those changes between the
In fact, using shapefiles as a means of data exchange shares many of the disadvantages
involved with database transfer. Data contained in the shapefile’s database
file must still be linked to modeling attributes to give the data meaning, units
must be specified, and data collections that span numerous database fields,
such as patterns, cannot be easily transferred using shapefiles.
In addition, certain modeling elements are treated differently by GIS than
by modeling software – in GIS, pumps and valves are generally represented as
point elements, while in modeling applications they are regarded as links. This
disparity must be resolved manually by the user when transferring this data
between the applications. It also demonstrates the lack of real integration
between the applications that is inherent in using shapefiles here.
While shapefiles store coordinate data, they do not possess awareness of network
connectivity, which is a critically important aspect of water distribution models.
Knowing which pipes connect to which nodes is a vital component for expanding,
editing, and calculating the model.
Half of the integration equation is the ability to transfer the calculated
results produced by the modeling software into the GIS. However, GIS software
does not natively support timeseries data, so to bring the results of an extended
period simulation into the GIS, the results for each time step must be imported
separately. Depending on the length of the extended period and the duration
of the time step, this can mean importing hundreds of database files.
Using shapefiles to transfer modeling data means that the modeling software
and the GIS are not unified; they are disparate applications, dependent on the
user for the transfer, synchronization, and definition of data between them.
Creating a unified whole
While providing a level of interoperability between modeling and GIS applications,
shapefile transfer does not truly provide integration, nor the transparent and
seamless interaction implied by the defining phrase ‘unified whole’.
The GIS and modeling software run as discrete entities, causing data separation
that hinders the modeling process.
Even modeling applications that natively use shapefiles to store the model’s
network spatial data cannot truly be said to integrate with GIS software. The
level of compatibility certainly increases, but the actual element input data
and calculated results are stored separately from the shapefile in proprietary
output files that need to be manually linked to the shapefile. This requires
the same userdependent management, definition, and oversight that is required
for simple database and shapefile connectivity. This type of compatibility
likewise runs outside of the GIS, and still requires the manual initialization
of data when switching between the two applications.
The challenge of providing true integration between GIS and water resource
modeling software can only be met by synthesizing the packages into a unified
whole, and WaterGEMS does exactly that. By actually working within the GIS environment,
WaterGEMS modeling software unifies the packages within a common interface,
without limiting the functionality of either the modeling software or the GIS.
The strengths of each can be utilized without the need for repeated database
or shapefile export/import, field linking, or the reentry of data. All modeling
elements and data are accessible to all GIS tools and functionality.
WaterGEMS also brings the ability to easily view and manage timeseries data
to GIS, providing an intuitive means of viewing the changing conditions during
an extended period simulation from within the GIS environment. Since all of
the model data is already present in the GIS, the need to import the results
of each time step is eliminated. This extension of core GIS functionality illustrates
the tight integration between the modeling software and GIS.
An important feature of modeling software is the ability to calculate and view
multiple scenarios, and with WaterGEMS this functionality is available from
within GIS, allowing users to quickly switch between scenarios without changing
the active result files.
Using the geospatial analysis abilities of GIS, WaterGEMS enables the creation
of advanced, intelligent modeling capabilities such as automated demand allocation, and network skeletonization for water resource modeling.
True GIS integration with WaterGEMS eliminates the problems encountered when
using outdated techniques of data exchange that actually only provide compatibility.
It also facilitates the use of GIS in water resource modeling applications
by seamlessly running within the GIS itself and by leveraging the advantages
of GIS applications. Manual data transfer and connection are no longer necessary,
greatly improving efficiency and resulting in substantial savings both in time
and in effort.
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