International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 1
Number 2
June 2007
129
Application of GNSS Integrated Technology to
Safety of Inland Water Navigation
D. Popielarczyk & S. Oszczak
University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
ABSTRACT: In the paper the description of some applications of satellite integrated technology, elaborated in
the Chair of Satellite Geodesy and Navigation of University of Warmia and Mazury in Olsztyn, to bathymetric
survey of Great Masurian Lakes is given. The Lake of Sniardwy, the largest lake in Poland with about 11,000
ha has been measured using this modern technology with precise satellite positioning of underwater stones
and shallow waters dangerous for sailors. Next the numerical map was elaborated and edited for sailors,
fishermen and tourists. Some conclusions and recommendation for future works on inland navigation charts
are also given.
1 INTEGRATED NAVIGATION
1.1 Safety on inland water reservoirs
Marine navigation is the process of planning and
controlling the safe movement of boat from one
place to another (Bowditch, N. 2002). The inland
waterways navigation especially includes piloting in
narrow canals, channels, rivers and shallow estuaries
mostly lakes. Safe navigation can not be done
without actual bathymetric maps, digital bottom
visualization and information about under water
obstacles.
In north east part of Poland there is situated
Warmia and Mazury region frequently called the
Land of a Thousand Lakes. It is the center of
recreation for tourists from all over Poland and from
abroad. There is an amazing opportunity for sailors
and fishermen. In the summer time there is almost
10,000 sailing boats on the Great Mazurian Lakes in
Poland, carrying 50,000 tourists every day.
Almost all of lakes do not have up-to-date
analogue or digital charts. The most part of them has
been measured almost 50 years go. Existing
analogue maps do not present the real and accurate
bottom surface. Unfortunately many of the
mentioned reservoirs have dangerous for sailors
shallow regions with stones and reefs. The
dangerous places make the inland waterways very
difficult to navigate. Therefore it is very important to
ensure the general safety which could be reached by
creating digital, bathymetric charts, marking the
inland waterways and especially dangerous shallow
stone reefs on inland waterways of Great Mazurian
Lakes.
The team of Chair of Satellite Geodesy and
Navigation of Warmia and Mazury University in
Olsztyn has developed integrated technology of
bathymetry surveying, which makes possible
navigation of the small hydrographic boat along the
pre-defined profiles, examination of bottom shape,
computation of water volume, elaboration of
bathymetric charts and monitoring of dangerous
shallow places.
For the developed Integrated Bathymetric System
a number of professional equipment units are used,
as follows: the EGNOS and DGPS/RTK receivers,
GPRS modems, EA 501 P Simrad single frequency
130
digital echo sounder, Imagenex SportScan side scan
sonar, YSI 600R water quality sonde and special
GPS/CAD software.
The hydrographic equipment is mounted on board
of the motorboat. The small but safe and easy to
use hydrographic boat, called “ORBITA”, is used
for raw-data collection during these integrated
measurements. The implemented technology allows
designing of measurement profiles, navigation along
the profiles, recording positions and bathymetric
data, making correlation of these both data and
finally creating digital bathymetric maps. The
developed Integrated Bathymetric System combined
with side scan sonar gives a great chance to study the
underwater environment, especially monitoring
underwater dangerous stones and shallow areas.
The paper presents application of GNSS
integrated technology to monitoring and safe sailing
on Great Mazurian Lakes.
Fig. 1. Lake Sniardwy location
1.2 Lake Sniardwy – the biggest lake in Poland
The most dangerous for sailors is the largest lake in
Poland called Sniardwy Lake with its surface area
over 10,000 ha. The lake is placed in south part of
the Land of a Thousand Lakes (see Figure 1). This
shallow reservoir has bad reputation due to
unexpected strong winds and storms. Thus, inland
waterways should be precisely determined and the
majority of existing underwater obstacles (mainly
stones and very shallow waters), dangerous for
sailors, should be precisely positioned on the
navigation analogue as well as digital charts.
The results of the experiments carried out on the
biggest lake in Poland, Lake Sniardwy, using GPS
receivers working in DGPS/GPRS and EGNOS
mode will be presented. Differential GPS satellite
measurements were based on the GPRS data
transmission system, originally developed in the
Chair of Satellite Geodesy and Navigation, of
Olsztyn University (Oszczak, B. & Oszczak, S. &
Ciecko, A. 2004).
2 GNSS INTEGRATED TECHNOLOGY
2.1 Integrated Bathymetric System
The research team of Chair of Satellite Geodesy and
Navigation has developed the integrated technology
of bathymetry surveying in order to examine under
water environment (Popielarczyk, D. & Oszczak, S.
2001). The developed Integrated Bathymetric
System basically consists of (see Figure 2):
The GNSS positioning system
The bottom detection system
The special GPS and CAD software.
2.2 GNSS equi pment
The Differential GPS positioning system uses two
Ashtech Z-Xtreme GPS receivers. The first of them,
placed at a known mark is a stationary receiver
called base or master reference station. There can be
used the permanent reference station or a local
station set up only for the dedicated project. The
base station receiver determines the errors of
measurement data between fixed and observed
station position (corrections). The DGPS corrections
in RTCM v. 2.2 format are sent via GPRS (General
Radio Packet Services) to the rover GPS receiver in
unknown location and can be applied to
measurement data.
The results of our experiments and analysis of
accuracy of boat positioning during bathymetric
survey show that the comparison of the phase OTF
mode horizontal position with coordinates obtained
in real time code Differential GPS show differences
from -0.95 m to 1.05 m for dB and dL (Popielarczyk,
D. & Oszczak, S. 2002). According to IHO
Standards for Hydrographic Surveys, where the
horizontal accuracy for Special Order reservoirs is 2
m, achieved accuracy is sufficient for majority of
bathymetry surveying.
Fig. 2. Integrated Bathymetric System
131
2.3 Hydrographic system
The hydrographic equipment includes EA 501 P
Simrad single frequency digital hydrographic echo
sounder, Imagenex SportScan Side Scan Sonar and
YSI 600R sonde for water quality sampling.
The EA 501 P system basically consists of
transducer, transceiver and personal computer. The
collected data are processed on-line for generation of
colour echograms and tables.
The echogram is presented on the Laptop display.
The file system allows recording selected data for
further analysis. Sample data may also be stored on
hard disk and replayed for demonstration of survey
echo data. A navigation receiver can be connected to
the Laptop serial port (NMEA-GLL format), and
position data can be provisionally combined with the
measured echo data. The EA 501 P Simrad general
specification is as follows: the transceiver 200 kHz
frequency, max. freshwater detection depth 600 m,
accuracy about 0.25% of measured range, transmitting
power 50 to 250 W, calculation interval for 0 to 10
per second.
The Imagenex SportScan is a dual channel
(2x330kHz), high resolution digital side scan sonar
operated directly from PC computer. The towfish
operates from a standard 12 Volt DC power supply
or boat's battery, and the RS-232 connector plugs
directly from the Kevlar towfish cable into the back
of a PC computer or laptop.
The SportScan software can read GPS raw data
into the PC computer, display it on the screen, and
use the speed over ground to adjust the aspect ratio
of the sonar image. Objects can have their height and
length determined with the click on the sonogram.
All data can also be stored on hard disk for later
display and analysis. The side scan sonar has
maximum operated depth of 30 m and it is used for
underwater objects such as big stones and wreck
localization. The last summer DGPS/SONAR
experiments indicate that the accuracy of underwater
object determination is of order of 1-2 m. Figure 3
shows the same object on the echogram (on the
right) and sonogram (on the left).
The bathymetric system combined with side scan
sonar gives a great chance to study the underwater
environment, and especially to monitor underwater
objects and dangerous stones.
Fig. 3. Under water object on the echogram and sonogram
The YSI 600R provides water quality sampling
for both surface water and groundwater. This sonde
measures temperature, conductivity, dissolved
oxygen, and pH. The speed of sound in water is
estimated by a simple empirical formula (Clay, C. S.
& Medwin, H. 1977). The YSI 600R sonde is also
used for pollution monitoring (Popielarczyk, D. &
Oszczak, S. 2002).
The special GPS and CAD software of the system
allows the measurement profiles to be designed,
enables navigation along the profiles, recording and
combining the positioning/bathymetric data, and
finally creating bathymetric maps. For elaboration of
raw-data the originally developed software Echo
Converter is used.
The Integrated Bathymetric System is mounted
on board of small, but safe and easy to operate
motorboat called “ORBITA”. It is perfectly suited
for raw-data collection during inland water
measurements.
3 SNIARDWY LAKE BATHYMETRIC
CAMPAIGN
3.1 Preparations for experiment
Some of Great Mazurian Lake has its waterways
marked by floating signs and dangerous places by
Cardinal Buoys in IALA (International Association
of Lighthouse Authorities) system. Unfortunately the
biggest reservoir Lake Sniardwy has not yet such a
system. That is why this lake was chosen to be
examined as the first. The project on the Lake
Sniardwy consists of the following stages:
DGPS/GPRS permanent and spare local reference
stations configuration
Designing of measurement profiles
Hydrographic system calibration
Bathymetric survey
Localization of underwater objects
132
Elaboration of measurement raw-data
Creation of bathymetric digital chart.
3.2 DGPS/GPRS permanent and spare local
reference stations configuration
The permanent DGPS/RTK/GPRS reference station
is situated about 30 km from test area in Gizycko, a
tourist town loated in the very heart of Great Mazu-
rian Lakes. Differential GPS satellite measurements
were based on the GPRS (General Radio Packet
Services) data teletransmission system, originally
developed by the Chair of Satellite Geodesy and
Navigation in cooperation with Biatel Company. The
level of GSM coverage and GPRS service quality in
the specific region of operation (on the lakes) is fully
sufficient for the purpose of the bathymetric surveys.
The DGPS corrections are sent to the rover Ashtech
Z-Xtreme GPS receiver every 3 seconds. In the
surroundings of the project area the backup local
reference station was activated (Ashtech Z-Surveyor
GPS receiver).
Thales Mobile Mapper GPS receiver was also
configured to receive EGNOS corrections.
The measurement profiles were designed on
digital shore map of the lake parallely, every 50
meters one after another.
3.3 Hydrographic system calibration
Before hydrographic sounding the single beam echo
sounder was calibrated. The YSI 600R sonde was
used to determine temperature and conductivity of
the water column from bottom to the surface. The
speed of sound in water was estimated by YSI 2SS
software using Clay and Medwin formula. The mean
value of sound speed was determined to be 1480
m/s. Simrad EA 501 P was also controlled by
conducting bar-check calibration. An average speed
of sound was entered directly into the echo sounder
before data acquisition.
Accurate sensor offsets was measured between
the echo sounder transducer and the reference water
level and then applied within the acquisition system.
The GPS antenna was mounted vertically over the
echo sounder transducer, which was placed in the
hull of “ORBITA” boat. Therefore no horizontal
offsets need to be applied.
3.4 Bathymetric survey
After the data acquisition system had been properly
configured and all of the necessary calibrations had
been completed, on-line data acquisition could
begin. The project was conducted by the team of the
Chair of Satellite Geodesy and Navigation. The raw-
data acquisition process took a lot of time and staff
effort. The total amount of data record time was
approximately 300 hours.
During the experiment, on board of the motor
boat two GPS receivers were installed: Thales
Mobile Mapper in EGNOS mode and Ashtech Z-
Xtreme working in DGPS/GPRS mode. The DGPS
unit was receiving real time corrections from base
reference station via GPRS Cellbox modem. At the
same time the receiver was sending out differentially
corrected boat position to:
The software ESRI ArcView 8.3, for navigating
along the pre-defined profiles using Laptop
monitor, in NMEA-GGA message format
The EA 501 P Simrad echo sounder in NMEA-
GLL format.
The memory cards of the base station, rover and
back up station receivers, stored raw observation
data to make possible computation of the boat
positions in post-processing mode.
In the navigation software the position of the boat
was displayed against the background of the digital
shore map on board screen. This allows the
navigation along pre-defined measurement profiles.
During the experiment the profiles were designed
parallely every 50 meters one after another.
Combined position and depth data were saved on
the Laptop hard disk, which was controlling
sounding the hydrographic system also.
The mean local water surface was taken as the
reference water surface during the project. The
kinematic post-processed OTF precise technique was
used to control the hydrographic survey and
adequate ellipsoidal height/water-level relationships
have been developed. The reference water surface
was reduced to the vertical datum in Poland based
on Kronstadt ’86.
3.5 Localization of underwater objects
The measurements on Great Mazurian Lakes
included localization of under water stones and reefs
and other objects also. Two hand held receivers with
ability to achieve EGNOS or DGPS/GPRS
corrections were used to collect over 280 coordinates
of shallow areas and stones on Sniardwy Lake.
The Imagenex SportScan side scan sonar was used
for tests of under water object detection. During
measurements two wrecks were found. One of then
is a wooden ferry sunk in Lake Kisajno. The second
one is a wreck of motorboat in Lake Krzywe (see
Figure 4).