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27The impacts of climate and land use changes on streamflow and sediment export were evaluated 28 for a humid (São Lourenço) and a dry (Guadalupe) Mediterranean catchment, using the SWAT 29 model. SWAT was able to produce viable streamflow and sediment export simulations for both 30 catchments, which provided a baseline for investigating climate and land use changes under the 31 A1B and B1 emission scenarios for 2071-2100. Compared to the baseline scenario , 32climate change scenarios showed a decrease in annual rainfall for both catchments (humid: -12%; 33 dry: -8%), together with strong increases in rainfall during winter. Land use changes were derived 34 from a socio-economic storyline in which traditional agriculture is replaced by more profitable land 35 uses (i.e. corn and commercial forestry at the humid site; sunflower at the dry site). Climate change 36 projections showed a decrease in streamflow for both catchments, whereas sediments export 37 decreased only for the São Lourenço catchment. Land use changes resulted in an increase in 38 streamflow, but the erosive response differed between catchments. The combination of climate 39 and land use change scenarios led to a reduction in streamflow for both catchments, suggesting a 40 domain of the climatic response. As for sediments, contrasting results were observed for the humid 41 (A1B: -29%; B1: -22%) and dry catchment (A1B: +222%; B1: +5%), which is mainly due to differences 42 in the present-day and forecasted vegetation types. The results highlight the importance of climate-43 induced land-use change impacts, which could be similar to or more severe than the direct impacts 44 of climate change alone. 45 46 47

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