Figure 5 : SE susceptibility maps for the Guadiana watershed: a) historical, b) future considering RCP 4.5, and c) future considering RCP 8.5.
The HIST-RCP 4.5 map shows a wider presence of areas characterized by an increase in absolute value of SE (t/ha/year) compared with HIST-RCP 8.5, especially in the south-west portion of the basin. On the other hand, HIST-RCP 8.5 map shows that under this extreme climatic scenario, there will be an increase of hotspots with high SE rates, probably because of the concentration of extreme rainfall events, while most of the basin will not experience big changes in SE susceptibility. Using the land cover variables as aggregation criterion, the SE values of the HRUs were averaged to homogenize soil and slope characteristics. According to the area characteristics, four main land covers were selected as the most representative of the basin, since together they occupy more than 95% of the entire territory: i) oats plantation (OATS), ii) evergreen forest (FRSE), iii) olive plantation (OLIV), and iv) the agroforestry system of “montado” (WPAS). Figure 7 shows the 20 years average (Fig. 7a) and 20 years maximum SE in t/ha/year (Fig. 7b) for each land cover. Results highlight that SE rate is in the order FRSE<OLIV<OATS<WPAS both for average and maximum values.