No abstract

This research proposes the acquisition of a time series from optical satellites to observe changes in the Venice lagoon, an ecosystem which is very challenging to monitor by means of in situ survey activities, let alone using remote sensing techniques, given the presence of land and sandbars (vegetated intertidal areas). The work describes the specific validation process performed by ISPRA on the results obtained as applied on some target sites of the Venice Lagoon, both natural and partially artificial islands, using fully artificial islands as reference.

<p>The UK coast is under  increasing risk due to coastal change, cliffs are collapsing endangering houses near the coast and of the 12,400 km of  coastline, 2,500 km present a flooding risk. Constant monitoring is necessary in order to keep coastal evolution under surveillance and to adapt the measures to mitigate the impact of coastal change. Earth Observation technology is unique in that it has now been available for over 25 years and currently there is a range of satellites both civil and commercial that are constantly viewing our coast. Satellite imagery provides large scale observation at a high spatial resolution with an average revisit time of 5 days for most missions. Temporal and spatial resolution are key components to provide a continuous monitoring service of a coast. Using the balance of ever increasing resolution coupled to a range of innovative techniques that make full use of the spectral signatures being captured enables us to recreate the coastal boundary to a high degree of reliability over complete national coastlines.</p><p>Our developed methodology combines different types of products to completely characterize the different coastal environments. The land/sea boundary is used to monitor changes along the coast and combine with a backshore land use, land cover classification map, we are able to bring contextual information on coastal vulnerability and their erosive potential. Our LiuJezek_CoastL processor extracts the instantaneous land/sea boundary from all satellite observations available and provides a vector line which represents the coast morphology depending on sea level at the time of the acquisition. This line is then corrected from all water dynamics such as waves, tidal level to create shorelines at a reference datum height. The error in positioning the shoreline is relaint on beach slopes, for example in the case of cliffs or civil works along the coast compared to long shelfing beaches. Our backshore classification, provides land use and land cover information which can correct the shoreline position according to the features present along the coast.</p>

This work proposes the use of automatic co-registered satellite images to obtain large, high frequency and highly accurate shorelines time series. High resolution images are used to co-register Landsat and Sentinel-2 images. 90% of the co-registered images presented vertical and horizontal shift lower than 3 m. Satellite derived shorelines presented errors lower than mission’s precision. A discussion is presented on the applicability of those shorelines through an application to Tordera Delta (Spain).