TY - JOUR
T1 - Mapping inland water bathymetry with Ground Penetrating Radar (GPR) on board Unmanned Aerial Systems (UASs)
AU - Bandini, Filippo
AU - Kooij, Lukas
AU - Karl Mortensen, Bjørn
AU - Caspersen, Marie Boeskov
AU - Gammelby Thomsen, Lasse
AU - Olesen, Daniel
AU - Bauer-Gottwein, Peter
PY - 2023
Y1 - 2023
N2 - Bathymetry of inland water bodies is essential for river maintenance and
flood risk management. Traditionally, in shallow water bodies,
bathymetry is retrieved by operators wading through the water body with
Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS),
whilst in deeper waters, it is retrieved with sonar instruments on
manned or unmanned boats. In the past, researchers have documented the
use of Ground Penetrating Radar (GPR) on boats (i.e. water-coupled GPR)
for monitoring the bathymetry of frozen and non-frozen water bodies.
Furthermore, GPR has been used on helicopters for monitoring ice and
snow thickness. However, deployment of GPR on board Unmanned Aerial
Systems (UASs) in non-frozen inland water bodies with electric
conductivity higher than 100 μS/cm (as is common in most inland
waterbodies in non-polar regions) is unexplored. In this paper, we
document the possibility to use drone-borne and water-coupled GPR in
several cross-sections located in three different waterbodies (1 lake
and 2 rivers) in Denmark. These waterbodies had different bed sediment
materials and vegetation conditions, an electric conductivity varying
from 200 to 340 μS/cm and depths up to 2.5 meters. Drone-borne GPR
showed accuracy similar to water-coupled GPR when compared to RTK GNSS
ground-truth measurements, with a Mean Absolute Error (MAE) of approx. 8
cm. The only limitations of drone-borne GPR were i) more restrictive
minimum depth requirement (typically 0.8-1.1 m for drone-borne GPR,
while 0.3-0.4 metres for water-coupled GPR) ii) requirement to fly the
GPR antenna at altitudes of approx. 0.5 meters above the water surface
to avoid high spreading losses and strong surface clutter events hiding
the signal. Finally, GPR measurements were benchmarked against
traditional sonar measurements, showing that GPR measurements
significantly outperform sonar measurements in waterbodies with medium
or high density of aquatic vegetation.
AB - Bathymetry of inland water bodies is essential for river maintenance and
flood risk management. Traditionally, in shallow water bodies,
bathymetry is retrieved by operators wading through the water body with
Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS),
whilst in deeper waters, it is retrieved with sonar instruments on
manned or unmanned boats. In the past, researchers have documented the
use of Ground Penetrating Radar (GPR) on boats (i.e. water-coupled GPR)
for monitoring the bathymetry of frozen and non-frozen water bodies.
Furthermore, GPR has been used on helicopters for monitoring ice and
snow thickness. However, deployment of GPR on board Unmanned Aerial
Systems (UASs) in non-frozen inland water bodies with electric
conductivity higher than 100 μS/cm (as is common in most inland
waterbodies in non-polar regions) is unexplored. In this paper, we
document the possibility to use drone-borne and water-coupled GPR in
several cross-sections located in three different waterbodies (1 lake
and 2 rivers) in Denmark. These waterbodies had different bed sediment
materials and vegetation conditions, an electric conductivity varying
from 200 to 340 μS/cm and depths up to 2.5 meters. Drone-borne GPR
showed accuracy similar to water-coupled GPR when compared to RTK GNSS
ground-truth measurements, with a Mean Absolute Error (MAE) of approx. 8
cm. The only limitations of drone-borne GPR were i) more restrictive
minimum depth requirement (typically 0.8-1.1 m for drone-borne GPR,
while 0.3-0.4 metres for water-coupled GPR) ii) requirement to fly the
GPR antenna at altitudes of approx. 0.5 meters above the water surface
to avoid high spreading losses and strong surface clutter events hiding
the signal. Finally, GPR measurements were benchmarked against
traditional sonar measurements, showing that GPR measurements
significantly outperform sonar measurements in waterbodies with medium
or high density of aquatic vegetation.
KW - Bathymetry
KW - Drone
KW - GPR
KW - Sonar
KW - UAS
KW - Water Depth
U2 - 10.1016/j.jhydrol.2022.128789
DO - 10.1016/j.jhydrol.2022.128789
M3 - Journal article
SN - 0022-1694
VL - 616
JO - Journal of Hydrology
JF - Journal of Hydrology
M1 - 128789
ER -