## 4 Results  
### Estuarine Mapping and Area Calculation  
The geomorphological features identified in the study sites encompass all the subsystems of Category 1: shoreline sandy environments, dunes, tidal flats/wetlands, channel and rocky units (Table 1) over almost 60 years. Although only 5 years of evolution maps are shown (Figures 2-4), the calculation of the areas were made on every site for all the years indicated in Figure 1.  
Figure 2: Historical evolution of the eco-geomorphological features identified in the San Vicente de la Barquera estuary (1956–2017). Figure 3: Historical evolution of the eco-geomorphological features identified in Guadiana River estuary (1956–2016). The symbol * after a feature name indicates that such a feature is still developing. The evolution of the SVB estuary during the last 60 years (Figure 2) shows a reduction in the area occupied by saltmarshes and, consequently, an increase in the area of mudflats. In the early 1990s, the anthropic features increased markedly at both sides of the estuary, in parallel with the general expansion of urbanization on the Spanish coast. On the eastern side of the estuary, the development of dune fields was directly limited by the increase _in anthropic features_. In this area, the littoral drift goes to the east. However, as indicated above, there is a local counter-drift conditioned by the morphology of the coast and subsequent wave refraction, making the formation of an external beach and dune fields possible. The beach remained almost the same thorough the entire study period, with slight  
Figure 4: Historical evolution of the eco-geomorphological features identified in Ebro River Delta mouth (1984–2017). variations due to differences in tidal level at the time the orthophotos were taken. The ebb tidal delta had little variation in shape, with no relevant effects on area. Regarding the sand flats and the sand bars, especially the ones in the channels of the eastern tidal flat, both increased in area with time, particularly near the main bridge. These processes were, very probably, facilitated by the main flow directions of the ebb and flood currents (see arrows in Figure 2). From the three estuaries, the GUA estuary (Figure 3) is the most stable, without notorious natural changes during the study period, but with a remarkable variation in the area of anthropic features around the saltmarsh due to touristic pressures. The urbanization of Isla Canela led to a loss of saltmarsh surface, which was transformed into urban area, crops or grasslands (transformed saltmarsh in Figure 3). Moreover, the area of sandy environments increased, with the formation of new dunes and the growth of the beach. The evolution of the sandy hooks upstream reveals the large availability of sediment in this area. With time, the initial hook was consolidated as a relict dune ridge, and a new active dune ridge was established with the development of a recent saltmarsh between both dune ridges. Additionally, a new hook developed at the end of the external beach in recent years (early 2000s to present), with an associated sheltered area (mudflats* in Figure 3). Very relevant for this system is the presence of a huge sediment bank formed in the outer part of the estuary and mapped as a group of sand bars to unify terms. This sand bank fluctuates over time, making it difficult to map. The drainage network became more developed and denser over the years, partly due to an increase in the quality of the orthophotos, but also to the natural evolution of the saltmarsh. Regarding the main active processes, the littoral drift in this zone moves eastward, although waves and tides have a crucial role in the development of morphologies in the lower part of the estuary, as indicated by the evolution of the main sandy structures (see black arrows in Figure 3). The EBR estuary suffered great changes between 1956 and 1984 (Figures 4 and 5).