Introduction
The MI-Safe basic tool give user from over the globe the possibility to find out if vegetation on a coast effects wave attenuation or not. The answer is yes or no, but ..... the science behind this is state of the art science under constant improvement and evaluation. The MI-Safe basic tool is based on global datasets that are questioned via OGC services via a web viewer. The data from these global datasets are used to query the results of a modelling exercise with XBeach with a range of conditions worldwide. The results are used to derive general rules on where vegetated foreshores might be effective as coastal protection, and on which factors determine their effectiveness.
The viewer
The viewer is build up of 3 main parts, the canvas where the maps are shown, the table of contents where a selection of layers can be toggled on or of and the modelling part. Next picture is a screendump of the viewer.
The modelling part enables users to draw a profile of the cost. Via OGC services (a WPS in this case) data is extracted over the profile. This data is then classified to certain rules and used to query the table of model results. The result is shown in a very basic way indicating whether or not vegetation is existent and or contributes to wave attenuation. Next picture gives an example.
The data
The data used for the modelling results is global open data. The datasets used are, including a link to the metadata:
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Using the above presented links to datasets of elevation/bathymetry, landcover and mangrove distribution will give enough information on the datasets itself. For the surges and the return periods the following paragraphs provide more information.
Waves
Wave data for return periods (Tr) of 1, 10 and 50 years are extracted from the ERA-interim dataset (Table XX, Figures XX and XX). Waves are generally lower in the tropics (e.g. less than 2 m between -30° to + 30°) than in temperate zones (where Hs>5m between 40°-70°).
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The picture below gives a global view of wave heights for a return period of 1 year.
Water levels
The water levels, which are a combination of tidal elevation and storm surge, have been chosen rather arbitrarily at 1, 3 and 6 m above MSL. Substantially higher levels occur are likely to occur at some places in the world. For instance, parts of Bretagne have a tidal range of well over 10 m. There, only 1 m of surge is required for MSL + 6m, which seems not extreme. The feeling is that the selected levels are representative of a large part of the world, especially areas near the equator where the application of the FAST tool seems most likely.