Abstract. In many countries, urban flooding due to local,
intense rainfall is expected to become more frequent because of climate
change and urbanization. Cities trying to adapt to this growing risk are
challenged by a chronic lack of surface flooding data that are needed for
flood risk assessment and planning. In this work, we propose a new approach
that exploits existing surveillance camera systems to provide qualitative
flood level trend information at scale. The approach uses a deep
convolutional neural network (DCNN) to detect floodwater in surveillance
footage and a novel qualitative flood index (namely, the static observer flooding index – SOFI) as a proxy for water
level fluctuations visible from a surveillance camera's viewpoint. To
demonstrate the approach, we trained the DCNN on 1218 flooding images
collected from the Internet and applied it to six surveillance videos
representing different flooding and lighting conditions. The SOFI signal
obtained from the videos had a 75 % correlation to the actual
water level fluctuation on average. By retraining the DCNN with a few frames from a
given video, the correlation is increased to 85 % on average. The results
confirm that the approach is versatile, with the potential to be applied to
a variety of surveillance camera models and flooding situations without the
need for on-site camera calibration. Thanks to this flexibility, this
approach could be a cheap and highly scalable alternative to conventional
sensing methods.