*3.1. Classification Result*

For the SVM supervised classification, a total of 15 ROIs were recognized, corresponding to 15 classes, 7 of them associated with vegetation classes. However, only four of these classes are within the salt marsh horizons considered in this work. Regarding the other three vegetation classes, one has been associated with macrophyte debris deposited in the uppermost zone of the salt marsh by an extreme high tide event, and the other two with the typical vegetation of the saline wall. These last two classes are outside the scope of this work and, therefore, will not be taken into consideration. Nevertheless, it is interesting that they can be distinguished from salt marsh species.

Of the 4.8 ha of surveyed salt marsh, the spatial mapping of the endmembers estimates a vegetation cover of 14.7% of the area. These species are distributed parallel to the mean sea line and in different elevation ranges.

In this work, the vegetation classes within the salt marsh horizons include four classes of salt marsh species and a fifth class associated with macroalgal debris. From high to low elevations, the distribution of these classes is macroalgal debris deposits first, followed by vegetation 1 and 2 in the mid-horizon, vegetation 3 within the transition zone, and vegetation 4 in the low horizon. The area covered by these classes is 2.9%, 9.2%, 34.3%, 28.9%, and 24.9% of the vegetated area, respectively (Figure 4).

**Figure 4.** Salt marsh vegetation distribution according to the SVM classification. The white line defines the boundaries of the surveyed area, corresponding to 4.8 ha. The macroalgae class is debris deposited in the uppermost zone of the salt marsh representing less than 3% of the vegetated space. Vegetation 1 and vegetation 2 are distributed along the medium marsh horizon, vegetation 3 corresponds to the transitional zone, and vegetation 4 spreads along the low marsh horizon. The classification is superposed on the orthomosaic obtained by the hyperspectral survey displayed in true colour combination.
