Technical Assistance
GIS/GPS Mapping
development of KRWA mapping program
GPS Mapping at Kansas Rural Water consists of two components: data collection and map production. A multitude of methods exist to collect system data, ranging from pencil drawings to digital CAD drawings. The five primary methods that have been investigated in the process of data collection by Kansas Rural Water are:
manual digitizing
heads up digitizing over scanned engineering drawings
heads up digitizing over digital orthophotography with engineering drawing reference
automated raster/vector conversion
and field data collection
KRWA has determined that the best process for data
development is a combination of two processes: heads up digitizing over digital
orthophotography with engineered drawing reference augmented with field data
collection.
The data from the field collection is imported over the digital orthophotography.
If the scale and projections are correct, the points appear on the aerial just
where they are in the real world. The heads up digitizing begins with the
placement of non-visible system features, those that could not be field
collected, over the aerial. Referring to the engineered drawings aids in the
correct placement of features such as line locations and the correct layout of
pipeline configurations, such as valve intersections. The field data collection
is crucial in that it shows the exact placement of a feature versus a close
approximation through the digitizing process.
How does the process work?
A city or RWD contacts KRWA expressing an interest in GPS mapping. A KRWA
representative will lead the system representative through a short
pre-assessment survey to determine what the system needs and how KRWA can best
provide that.
After the city or RWD decides to proceed with the GPS mapping, the next step is
to collect data. The field data collection involves using GPS equipment to
record the coordinates of visible system features (valves, hydrants, meters,
trenches, markers, etc.). The accuracy of the equipment used by KRWA is within
one foot of actual location of the feature. This means that after a point is
collected with KRWA's equipment, it is possible to navigate back to within one
foot of that exact position with comparable GPS equipment. One-foot accuracy is
very adequate for water and wastewater utilities.
It is essential that the city or RWD participate in the data collection process.
Time in the field is minimized and accuracy is increased if the system
representative drives the vehicle to the desired locations and the KRWA
technician records the data. The system representative knows the system and the
KRWA technician is able to do a better job logging the information.
KRWA provides cost estimates for the data collection of a water or wastewater
system. The estimated cost is based on the number of features to be data
collected. KRWA charges an hourly rate based on the number of points to be
collected. If the utility is prepared for data collection by pre-locating and
marking all features to be collected, the data collection can be performed more
efficiently, thus reducing the overall cost of the project.
What does the system receive?
KRWA's map production can generate printed maps and a digital map file. The
printed maps can be large-scale wall maps, 42" by 42+", showing the major
features with just about any layer desired (aerial photos, streets, sections,
railroads, rivers and streams, etc.).
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The printed maps can also be generated
into a map book format. The map book is a bound 18" by 24" book of high-detail
maps printed at whatever scale the utility desires. An index of detail sheets is
also included. The digital map file can be viewed and printed with free software
that KRWA will provide. The software and file can be used on nearly any
Pentium-level computer.
Feature attributes, details such as size and date of installation, can be added
and edited with additional programming. The city or RWD can also utilize
after-market products such as hand-held computers in conjunction with a GPS
attachment in order to navigate in the field. The possibilities are limitless
and the costs incurred with developing a Geographic Information System are
solely dependent on the needs of the utility and its future intentions.
KRWA will be here to help you develop and implement your mapping to meet future
needs of your utilities and your community. The main advantage KRWA guarantees
is that you will be in control of your data. You will not find any more
reasonable costs for these services.
KRWA is prepared to respond to your interest by providing a pre-assessment. KRWA
staff also are pleased to attend a meeting of your board or council to further
discuss and demonstrate how you can obtain better quality maps at affordable
costs. Email GIS Coordinator, Pete Koenig at
pete@krwa.net.