Videometry applied to impact weather characterization: coastal risk in Basque Country.

The analyses of coastal environments using video images have proven to be an efficient methodology. In the Basque case, the so-called “KOSTASystem”, developed by AZTI in collaboration with different institutional agents, allows monitoring different aspects of coastal dynamics. This coastal videometry system consists of cameras installed on the coast that allow images to be captured and spatially referenced. Such systems have been used worldwide to monitor the morphological configuration of beaches, dunes, channels and bars, but in recent years also to obtain reliable information on sea conditions and in the characterization of waves on beaches, among others applications.

Here we present a local application for impact weather monitorization, particularly in the field of “maritime-coastal risk: impact on the coast” as defined by the operational Basque severe weather protocol. Using KOSTASystem video imagery, images processing and computer vision algorithms, we have developed an automatic real time wave run-up impact monitoring system in some representative and selected locations on Basque shoreline.  

In this paper, we present main technical characteristics of the system and its operational implementation in the Basque Meteorology Agency (Euskalmet) for analysis, surveillance and monitoring purposes during and after coastal-maritime risk episodes. We also summarize our experience and some conclusions from the development and operational perspective.

The KOSTASystem videometry system covers different points of the Basque coast including ports and promenades areas. For instance, in Zarautz case is possible to characterize flood situations due to waves on the promenade or in Bermeo case waves impact in the port area. The sequences of images captured by the cameras are used for the generation of instantaneous images and integrated in time (timestack) by accumulating over a certain period of time rows of pixels from a defined transect on the image, previously converted from oblique to a plane metric image. As long as these transects are properly determined, they will reflect the temporal evolution of the wave run-up and the flooding or overtopping of the body of water in the predefined dry area for different positions of the image. Later on, automatic identification of run-up, partial and total overtopping is made, applying to different images some computer vision algorithms like the Otsu`s optimal thresholding and Radon Transform methodologies.

In this contribution, we present not only details of the implementation of automatic recognition systems using computer vision techniques; we also present other relevant aspects for the operational implementation. We summarize key characteristics for the downloading, archiving and integration of different images and products in the automatic monitoring and surveillance systems and their inclusion in the operational intranet in Euskalmet/Tecnalia. Finally, we present some conclusions focusing on usability for different operational tasks like analysis, surveillance, prediction and validation.