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

Landslides have frequently occurred in last years, due to the disorderly growth of the cities and the occupation of risk areas by the poor population, causing social, environmental and economic impacts. Urban areas in expansion move to geologically unstable areas and topographically inclined, such as the River Bengalas Basin, located in the city of Nova Friburgo, mountainous region of the State of Rio de Janeiro, Brazil. This article aims to present the model developed and used to evaluate the susceptibility and vulnerability of the River Bengalas Basin to landslides, which in January 2011, with the occurrence of heavy rains, caused landslides that impacted in the death of 429 people in city of Nova Friburgo. For the case study, several investigations have been made related to the areas of the basin, such as slope, soil conditions, lithology, land use and cover, vertical curvature, horizontal curvature, and precipitation data. With this study it was possible to understand how the natural and anthropics elements of the basin are related to the local dynamics of the disasters regarding to their interferences in the induction of landslides; evaluate the effectiveness of the guidelines of the Plano Diretor Participativo do Município de Nova Friburgo regarding the landslides; identify the susceptible and vulnerable basin areas to landslides and calculate the rates of susceptibility and vulnerability to landslides from new calculation model proposed..

A robust hydrological impact assessment is indispensable for mitigation and adaptation planning. This study presents an integrated modelling methodology for evaluating climate change impacts on water availability, sediment yield and extreme events at the catchment scale. We propose the use of the spatial–temporal Neyman–Scott Rectangular Pulses (STNSRP) model—RainSim V3 and the rainfall conditioned daily weather generator—ICAAM‐WG, as well as the physically based spatially distributed hydrological model—SHETRAN. The change factor approach was applied for obtaining unbiased rainfall and temperature statistics. The ICAAM‐WG was developed based on the modified Climate Research Unit daily Weather Generator (CRU‐WG). The methodology is proposed to generate synthetic series of hourly precipitation, daily temperature and potential evapotranspiration, hourly runoff and hourly sediment discharge. We demonstrated a possible application in a 705‐km2 Mediterranean climate basin in southern Portugal. The case study showed the evaluation of future climate change impacts on annual and monthly water balance components and sediment yield, annual and seasonal flow duration curves, empirical extreme value distributions and the theoretical fits. It did not consider the possible uncertainty due to the limit of computational resources. The methodology can be well justified as follows: (a) the use of synthetic hourly instead of daily precipitation enables SHETRAN to be more capable of reproducing reliable storm runoff processes and the consequent sediment transport processes; (b) the use of SHETRAN makes possible the impact assessment to be accessible for any model grid square within the study basin; (c) the use of a statistical–stochastic downscaling method facilitates the generation of the synthetic series with unlimited length. It makes possible robust hydrological impact assessments if uncertainties related to the global climate model, regional climate model, greenhouse gas emission scenario, downscaling method, hydrological model and observational data are considered.

Downscaling is usually necessary for robust hydrological impact assessments. This may be undertaken using a wide range of methods, including a combination of dynamical and statistical‐stochastic downscaling. This study uses the Spatial–Temporal Neyman‐Scott Rectangular Pulses model—RainSimV3, the precipitation‐conditioned daily weather generator—ICAAM‐WG, and the change factor approach for downscaling synthetic climate scenarios for robust hydrological impact assessment at middle‐sized basins. The ICAAM‐WG was developed based on the concept of the Climate Research Unit daily weather generator (CRU‐WG), motivated by the need for improved representation of heat waves by downscaling methods given the positive feedback between low soil moisture and high air temperature. We demonstrated the validity of the proposed methodology in the 705‐km2 Mediterranean climate basin in southern Portugal. The results show that, for the control period 1980–2010, both RainSimV3 and ICAAM‐WG reproduced not only the mean climatology, but also extreme wet and low precipitation events, as well as the extremes of temperature and heat waves. We found that downscaling with ICAAM‐WG (SIM6), which uses second‐order autoregressive processes for the simulation of temperature during consecutive dry and wet days, outperformed ICAAM‐WG (SIM4), which used only first‐order autoregressive processes, leading to improved simulation of heat waves. ICAAM‐WG (SIM6) well reproduced observed heatwave extremes with return periods of up to 30 years; however, ICAAM‐WG (SIM4) overestimated these extremes substantially. This indicates the importance of incorporating second‐order autoregressive processes in the simulation of heatwave length. In the context of climate warming, the proposed methodology provides a tool to improve downscaled projections of future extremes with confidence intervals for not only wet events but also dry spells and heat waves.

Southern Europe has been experiencing an accelerated intensification of agricultural systems in the last decades with consequent environmental effects. This study aimed to evaluate the effects of agricultural land use in two small-medium river basins in the South of Portugal, regarding: (i) water quality and stream habitat; (ii) fish fauna; and (iii) soil. Sampling included fish captures, water, and soil sample collection. Hydromorphological habitat features were also assessed. Land use was quantified at the basin and local scales. Results showed that the most negative effects were associated with intensive, heavily irrigated, fertilized, and pastured local systems, mostly represented at the basin scale by olive groves, irrigated crops, and pastures. Conversely, local agricultural intensity did not prove to be a threat to the integrity and quality of the soil, seeming to ensure the sustainability of the local uses and their systems. Negative effects were observed on water quality and instream habitat and degradation of riparian vegetation, resulting in fish assemblages' impoverishment. This study contributes to a comprehensive approach to the effects of agricultural land use, highlighting the need to integrate the results of different natural resources to efficiently support policy and decision makers toward a sustainable agriculture, water management, and land use planning.

Para evaluar los efectos a largo plazo de diferentes prácticas culturales en el medioambiente y suelo, se realizó un estudio comparativo entre un sistema de producción de cereales de secano de conservación y otro tradicional, a lo largo de 10 años consecutivos. El sistema de conservación ha recurrido a siembras directas, mientras que el tradicional al laboreo del suelo. En un suelo tipo Vertic Cambisol en Portugal se evaluó el contenido en materia orgánica, la relación carbono/nitrógeno, la densidad aparente, la cantidad, dimensión y estabilidad de la agregación, la macroporosidad de campo y la capacidad de almacenamiento de agua. Los resultados han demostrado que en el sistema de conservación hay una variación en las características del suelo que conducen a una mayor capacidad para producir vegetales, gestionar los recursos hídricos, secuestrar carbono orgánico y resistir a la erosión. Estos resultados tienen implicaciones positivas en la sustentabilidad de los sistemas agrícolas que recurren a siembras directas en suelos de textura fina de las áreas mediterráneas continentales en Europa.

ResumenSe realizó un estudio comparativo entre un sistema de producción de cereales de secano de conservación y otro tradicional, con el fin de evaluar los efectos a largo plazo de diferentes prácticas culturales en el combate a la desertificación. El sistema de conservación ha recurrido a siembras directas a lo largo de 10 años consecutivos, mientras que el tradicional al laboreo del suelo. En un suelo tipo Chromic Vertisol en Portugal se evaluó a partir de imágenes en 2D, la continuidad del espacio poroso y, por tanto, la dinámica del agua del suelo. Para tener una buena representatividad de la zona bajo estudio, se analizaron muestras de 250 cm 2 de suelo. Los resultados muestran que el sistema conservador, induce un aumento de la continuidad del espacio poroso en profundidad. Así, las prácticas culturales conservadoras, producen alteraciones en el régimen hídrico del suelo, siendo una importante estrategia a adoptar, como factor que interviene en el ciclo hidrológico y como acción concreta de lucha contra la desertificación. Palabras clave: suelo, prácticas culturales, siembra directa, régimen hídrico, desertificación Cultural Practices Study, Soil Porosity and Water Management against Desertification Combat AbstractTo evaluate the long term effects of different cultural practices in the desertification combat, a comparative study between a dryland conservative cropping system of cereals and another more traditional one was done. The conservative system has had direct seeding along 10 consecutive years, while the traditional one has had soil tillage. On a soil of the type Chromic Vertisol in Portugal the continuity of the porous space and therefore the water dynamics of the soil were evaluated using 2D images. To have a better representation of the area under study, soil samples of 250 cm 2 were analyzed. The results, demonstrated that the conservative system, induces an increase of the porous space continuity in depth. Thus, the cultural conservative practices produce alterations in the water regime of the soil, being an important strategy to adopt, as intervening factor in the hydrologic cycle and as a concrete action against desertification.

No abstract