River Monitoring with Ground-based Videography - Fluvial Remote Sensing for Science and Management - page 370

manually. Camera model and internet transmission
speeds restricted the system on the Ain River to image
frequencies of 5 Hz, which was not optimal because
it reduced the correlation between images and made
the identification of floating wood more difficult.
Higher frequencies should become the norm as internet
transmission speeds improve.
The analysis of video for monitoring of discharge
and floating wood is a developing scientific field and
sources of error are still significant. Errors were reduced
using filtering algorithms based on statistical techniques
and secondary properties of the objects. However, not all
errors were removed and it was not possible to get accurate
measurements under all conditions. More techniques are
necessary to accurately filter data and to establish criteria
for discarding poor quality estimates. A significant data
hole remains at night, where illumination is not sufficient
to use conventional cameras. Despite the use of infrared
sensitivity, nighttime readings were of poor quality, while
fog, direct sun and some reflections caused an unfilterable
hole in the data. Continued research on the improvement
of analysis techniques is warranted. Standardisation of
analysis procedures will increase the ease of application
for river management.
Continued development of videography for river man-
agement could lead to some exciting new applications.
One area for study is themeasurement of velocity and esti-
mation of discharge from a helicopter (Fujita and Hino,
2003, Fujita et al., 2007a). Such a development would
allow the rapid characterisation of hydraulic habitats for
fish and improve morphological models of shear stress
and erosion during floods. Another possible application
is to implement wood detection algorithms in real-time.
Such an application would allow videography to be used
as an early warning system where infrastructure or other
areas of interest are at risk of flooding or failure due to
wood accumulations. The ability to measure river dis-
charge, velocity and wood transport in a continuous and
remote fashion at a moderate cost should ensure that
videographic systems are widely implemented for river
management in the future.

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