BUSCADOR RECOLECTA

This study documents the impacts of engineering works on flood risk and channel dynamics of the maximum geomorphic flow reach of the Middle Ebro River (Spain) over the last ninety years. The map reveals how the construction of transversal transport lines and their ineffective design and maintenance has contributed to an elevated risk of flooding and channel avulsion at this location. In addition, the development of flood protection structures has restricted the natural dynamics of the river. These modifications have restricted the passage of flood waters, ultimately increasing flood hazards, by changing the area and depth of inundation and extending the flood hydrograph. The map allows for the interpretation of key processes, forecasting of flood hazards, and the evaluation of possible mitigating actions. These findings reconfirm that reducing space for the mobility of a river is not a good management solution and further aggravates the current situation.

En el presente estudio se analizan las variaciones espaciales y temporales entre Isobioclimas de la España peninsular en dos periodos climáticos normales consecutivos (1951-1980 y 1981-2010). Los criterios aplicados para caracterizar los Isobioclimas son los de la Worldwide Bioclimatic Classification System (WBCS). El estudio se llevó a cabo con las bases de datos de alta resolución espacial de temperatura y precipitación mensual, MOTEDAS y MOPREDAS respectivamente, en su versión de malla de 10x10 km. En el primer periodo normal se han encontrado 40 Isobioclimas y 36 en el segundo. Entre ambos periodos el 38,56% del territorio peninsular español cambia de Isobioclima, mientras que el 61,44% restante permanece estable. Considerando como movilidad de un Isobioclima su cambio de ubicación en el espacio geográfico, medible por la superficie que cede a otros, más la superficie que recibe de otros, todos los Isobioclimas se mueven y el total de los traslados asciende al 77,12% del territorio., In the present study spatial and temporal variations amongst Isobioclimas of mainland Spain are analyzed for two consecutive normal climatic periods (1951-1980 y 1981-2010). The criteria used for characterizing the Isobioclimates are those of the Worldwide Bioclimatic Classification System, WBCS. The study was carried out with high spatial resolution databases of monthly average temperature and monthly rainfall, MOTEDAS and MOPREDAS, in its version of mesh 10x10 km. 40 Isobioclimas have been found in the first normal period, and 36 in the second. Between the two periods 38.56% of the Spanish mainland changes Isobioclima, and the other 61.44% remains stable. Considering as mobility of a Isobioclimaits the changes of the geographical site, measurable by the surface it yields to others, plus the surface it receives from others, all Isobioclimates change places and total transfers rises to 77.12 of the territory., Ministerio de Ciencia e Innovación, Gobierno de España, Proyecto DESEMON, CGL2014-52135-C3-3-R. Gobierno Regional de Aragón DGA-FSE (Grupo de Investigación Consolidado “Clima, Agua, Cambio Global y Sistemas Naturales”). Dhais Peña-Angulo es becaria de doctorado del Programa FPI del Ministerio de Ciencia e Innovación.

Los tipos de tiempo se definen como situaciones sinópticas específicas, clasificadas según diversos criterios. La clasificación de Jeckinson y Collison es automática, y emplea datos de presión de superficie y diversos algoritmos que definen 26 tipos de tiempo. Se ha estudiado la relación entre los tipos de tiempo y las temperaturas mensuales de la Península Ibérica de la base de datos “MOnthly TEmperature DAtabase of Spain”. El análisis de la relación muestra una respuesta asimétrica entre las costas este y oeste peninsular en presencia de advecciones atlánticas o mediterráneas. Así, las advecciones del Oeste favorecen el descenso de temperaturas en la fachada atlántica del territorio, mientras que en la costa mediterránea se observa un aumento de las mismas. Sin embargo, cuando tiene lugar las advecciones del Este ocurre lo contrario, descenso de temperatura en la costa mediterránea y aumento térmico en la fachada atlántica. La distribución espacial de las principales cadenas montañosas parece ser la clave del reparto espacial de las temperaturas y del efecto foehn que tiene lugar a gran escala en la Península Ibérica., Weather types are defined as specific synoptic situations that can be classified using several criteria. Jeckinson and Collison’s classification is an automatic algorithm that uses surface pressure data to define 26 weather types. In this study, the relationship between weather types and monthly temperatures has been studied for the Iberian Peninsula, based on data from the “MOnthly TEmperature DAtabase of Spain” database. This analysis shows an asymmetric behaviour in the East and West coasts of the peninsula in response to Mediterranean and Atlantic advection. A west advection leads to decreases in temperatures in the Atlantic facade of the studied territory, while an increase of temperatures is observed along the Mediterranean coast. With an East advection the opposite phenomenon occurs: temperatures decay on the Mediterranean coast and increase in the Atlantic facade. The spatial distribution of the main mountain chains in the Iberian Peninsula appears to be the key element explaining the spatial distribution of temperatures and the observed Foehn’s effect occurring at a large scale in this territory., Ministerio de Ciencia e Innovación, Gobierno de España, Proyecto DESEMON, CGL2014-52135-C3-3-R. Gobierno Regional de Aragón DGA-FSE (Grupo de Investigación Consolidado “Clima, Agua, Cambio Global y Sistemas Naturales”). Dhais Peña-Angulo es becaria de doctorado del Programa FPI del Ministerio de Ciencia e Innovación.

Durante la segunda mitad del siglo XX en la España peninsular se ha registrado una tendencia positiva generalizada de las temperaturas, variable en su intensidad, distribución espacial, medida termométrica (máxima o mínima) y estación del año. Paralelamente, durante las décadas recientes en España se ha asistido a profundas transformaciones de los paisajes con la modificación de extensas áreas por urbanización, infraestructuras, regadíos, incendios etc. En general se acepta que las temperaturas diurnas (Tmax) dependen de factores globales, mientras las nocturnas (Tmin) dependen en mayor medida de factores locales, especialmente cambios de usos del suelo. En el presente trabajo se analiza la posible relación entre las tasas de calentamiento observadas y los cambios de uso del suelo observados en la España peninsular evaluados por diferentes grados de accesibilidad, como indicador de dichos cambios. El estudio utiliza la base de datos de temperaturas promedio mensuales de Tmax y Tmin, MOTEDAS (resolución 10x10 km) y se enmarca dentro del proyecto DESEMON. Los primeros resultados (periodo 1960-2010) sugieren una menor relación entre las superficies artificiales evaluadas por la accesibilidad y Tmax, mientras que se detecta una relación positiva con Tmin en las cuatro estaciones y el promedio anual, lo que pudiera sugerir algún tipo de efecto de la transformación de los paisajes sobre las temperaturas nocturnas., During the second half of the 20th century on mainland Spain, there is a positive trend widespread of the temperatures, variable in the intensity, special distribution, maximum and minimum and the seasonality. Generally, the change in the maximum temperatures (Tmax) is related to global factors meanwhile the night temperatures (Tmin) are associated with local factors, especially with the land use changes. In this research, we analyze the relationship between the warming rates observed and the land use change assessed through the different levels of the accessibility index. In this case, we are using the MOTEDAS dataset (resolution 10x10km2), for monthly average maximum and minimum temperatures created within the DESEMON project. The first results for the period 1960-2010 suggest that there is a lower relationship between the artificial surfaces evaluated in the accessibility index and the Tmax, while is found a positive relationship with the Tmin in all of the seasons and with the annual average, this may suggest some kind of effect of the accessibility in the night temperatures., Ministerio de Ciencia e Innovación, Gobierno de España, Proyecto DESEMON, CGL2014-52135-C3-3-R. Gobierno Regional de Aragón DGA-FSE (Grupo de Investigación Consolidado “Clima, Agua, Cambio Global y Sistemas Naturales”). Dhais Peña-Angulo y Celia Salinas-Solé son becarias de doctorado del Programa FPI del Ministerio de Ciencia e Innovación.

En una serie temporal de datos el signo de su tendencia, su significación y su tasa varían según el periodo seleccionado. Este hecho tiene gran importancia en el análisis climático para poder comparar diferentes investigaciones, y relevancia actual en el debate referido al “hiato térmico”. En este trabajo se presenta un análisis de las variaciones de la tendencia de las temperaturas estacionales promedio de las máximas y mínimas de España peninsular (1951-2010) procedente de la base de datos MOTEDAS. La significación de la tendencia se evalúa con el test de Mann-Kendal, y la tasa con el estadístico de Sen. Los resultados muestran la ausencia de tendencias significativas recientes en invierno y otoño en máximas (Tmax) y mínimas (Tmin). En el mismo periodo la tendencia de Tmax en primavera no es significativa, mientras Tmin ha continuado siéndolo. Las tendencias de verano de Tmax y Tmin no son significativas desde al menos hace dos décadas. Las tasas de Tmax y Tmin de primavera y verano, las dos estaciones donde el aumento térmico ha sido más notable, son decrecientes en las décadas más recientes y en general la tasa de Tmin ha superado a la de Tmax desde inicios de la década de 1990., In a temporal data series the signal of trend, intensity and significance vary accordingly selected period, and this is especially true in climate analyses. In this research we present an analyses of seasonal trend variations of maximum and minimum temperature in Spanish conterminous land (1951-2010). Significance of trends is identified by using Man-Kendall test, and rate by Sen´s approach. The results show no significant trend in winter and autumn in maximum and minimum temperature in recent decades. Spring maximum is not significant in recent decades but is significant in minimum; summer trends are not significant for the last decades. The rates of maximum and minimum for the last decades decrease, and minimum usually show highest value than maximum from the beginning of 90´s., Ministerio de Ciencia e Innovación, Gobierno de España, Proyecto DESEMON, CGL2014-52135-C3-3-R. Gobierno Regional de Aragón DGA-FSE (Grupo de Investigación Consolidado “Clima, Agua, Cambio Global y Sistemas Naturales”). Dhais Peña-Angulo es becaria de doctorado del Programa FPI del Ministerio de Ciencia e Innovación.

Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. The results indicate two different temporal patterns: the first weather type exhibits (during the cold period: autumn and winter) westerly flows that produce the highest rainfall, runoff, and sediment yield values throughout the territory; the second weather type exhibits easterly flows that predominate during the warm period (spring and summer) and it is located on the Mediterranean coast of the Iberian Peninsula. However, the cyclonic situations present high frequency throughout the whole year with a large influence extended around the western Mediterranean basin. Contrary, the anticyclonic situations, despite of its high frequency, do not contribute significantly to the total rainfall, runoff, and sediment (showing the lowest efficiency) because of atmospheric stability that currently characterize this atmospheric pattern. Our approach helps to better understand the relationship of WTs on the seasonal and spatial variability of rainfall, runoff and sediment yield with a regional scale based on the large dataset and number of soil erosion experimental stations., Spanish Government (Ministry of Economy and Competitiveness, MINECO) and FEDER Projects: CGL2014 52135-C3-3-R, ESP2017-89463-C3-3-R, CGL2014-59946-R, CGL2015-65569-R, CGL2015-64284-C2-2-R, CGL2015-64284-C2-1-R, CGL2016-78075-P, GL2008-02879/BTE, LEDDRA 243857, RECARE-FP7, CGL2017-83866-C3-1-R, and PCIN-2017-061/AEI. Dhais Peña-Angulo received a “Juan de la Cierva” postdoctoral contract (FJCI-2017-33652 Spanish Ministry of Economy and Competitiveness, MEC). Ana Lucia acknowledge the "Brigitte-Schlieben-Lange-Programm". The “Geoenvironmental Processes and Global Change” (E02_17R) was financed by the Aragón Government and the European Social Fund. José Andrés López-Tarazón acknowledges the Secretariat for Universities and Research of the Department of the Economy and Knowledge of the Autonomous Government of Catalonia for supporting the Consolidated Research Group 2014 SGR 645 (RIUS- Fluvial Dynamics Research Group). Artemi Cerdà thank the funding of the OCDE TAD/CRP JA00088807. José Martínez-Fernandez acknowledges the project Unidad de Excelencia CLU-2018-04 co-funded by FEDER and Castilla y León Government. Ane Zabaleta is supported by the Hydro-Environmental Processes consolidated research group (IT1029-16, Basque Government). This paper has the benefit of the Lab and Field Data Pool created within the framework of the COST action CONNECTEUR (ES1306).

In this paper we present a detailed spatial assessment of the association between atmospheric synoptic conditions (the weather types, WT) and fires on the Spanish mainland. The WT approach allows the continuum of atmospheric fields to be compressed into a few comprehensive patterns, providing meaningful information on the movement of air masses, wind direction and, ultimately, wind speed. We analyzed a total of 291,547 individual fires from the official Spanish Fire database (1974–2014) and corresponding daily WT patterns on the Iberian Peninsula from the daily NCEP/NCAR Reanalysis database, 1951–2015. Underlying spatial patterns of association among fire and weather types were explored by means of self-organizing maps (SOM) coupled to hierarchical clustering.

Our analyses have detected that fires tend to occur and become largermore likely under certain atmospheric conditions suggesting that specific weather patterns can promote or boost fire events. From a pyrogeographical point of view, the contribution of WTs to wildfires on the Spanish mainland seems to be highly diverse, and displays several temporal and spatial patterns. The northwest region responds mostly to eastern flows during summer and southern during winter. Fires in the northern Mediterranean coast are promoted by northerly flows while in southern regions fires are linked to C or SE extreme heat episodes during summer. Overall, fires activity usually increases in the lee ward of mountain ranges depending on the prevalent flow from WTs, and thus related to adiabatic heating of the air flow., This work is supported by the projects CGL2014-52135-C3-3-R and CGL2017-83866-C3-1-R, financed by the Spanish Government, Ministry of Economy and Finance and FEDER, and the Regional Council of Aragón DGA-FSE (Grupo de Investigación Consolidado ‘Clima, Agua, Cambio Global y Sistemas Naturales’). Marcos Rodrigues Mimbrero is a postdoctoral research fellow in the Juan de la Cierva program supported by the Spanish Ministry of Economy and Finance (FJCI-2016-31090); Adrian Jiménez-Ruano is a granted FPU-PhD student (Ref. 13/06618).

Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. We investigated the relationships between synoptic atmospheric patterns (i.e. weather types, WTs) and runoff, erosion and sediment yield throughout the Mediterranean basin by analyzing a large database of natural rainfall events at 68 research sites in 9 countries. Principal Component Analysis (PCA) was used to identify spatial relationships of the different WTs including three hydro-sedimentary variables: rainfall, runoff, and sediment yield (SY, used to refer to both soil erosion measured at plot scale and sediment yield registered at catchment scale). The results indicated 4 spatial classes of rainfall and runoff: (a) northern sites dependent on North (N) and North West (NW) flows; (b) eastern sites dependent on E and NE flows; (c) southern sites dependent on S and SE flows; and, finally, (d) western sites dependent on W and SW flows. Conversely, three spatial classes are identified for SY characterized by: (a) N and NE flows in northern sites (b) E flows in eastern sites, and (c) W and SW flows in western sites. Most of the rainfall, runoff and SY occurred during a small number of daily events, and just a few WTs accounted for large percentages of the total. Our results confirm that characterization by WT improves understanding of the general conditions under which runoff and SY occur, and provides useful information for understanding the spatial variability of runoff, and SY throughout the Mediterranean basin. The approach used here could be useful to aid of the design of regional water management and soil conservation measures., This research was supported by projects funded by the MINECO-FEDER: CGL2014-52135-C3-3-R, CGL2014-59946-R, CGL2015-65569-R, CGL2015-64284-C2-2-R, and PCIN-2017-061/AEI. When this manuscript was first submitted Estela Nadal-Romero and Damià Vericat received a “Ramón y Cajal” postdoctoral contract (RYC-2013-14371 and RYC‐2010‐06264, Spanish Ministry of Economy and Competitiveness, MEC). Damià Vericat is now a Serra Húnter Fellow at the University of Lleida. María Fernández-Raga received a “José Castillejo” postdoctoral grant (Spanish Ministry of Education, Culture and Sports). Carla Ferreira was supported by a post-doctoral research grant from the Portuguese Science and Technology Foundation (SFRH/BPD/120093/2016). Mariano Moreno-de las Heras received a Juan de la Cierva postdoctoral contract (IJCI-2015-26463) from the MEC. José Andrés López-Tarazón received a Vicenç Mut postdoctoral fellowship from the Autonomous Balearic Government (CAIB PD/038/2016). José Andrés López-Tarazón and Ramon Batalla also acknowledge the Secretariat for Universities and Research of the Department of the Economy and Knowledge of the Autonomous Government of Catalonia for supporting the Consolidated Research Group 2014 SGR 645 (RIUS- Fluvial Dynamics Research Group), and the CERCA Programme. This paper has benefited from the Lab and Field Data Pool created within the framework of the COST action CONNECTEUR (ES1306).

Large rainfed, dryland areas were transformed into irrigated land in northeast Spain, where rivers from the Pyrenees Range ensure the availability of abundant water resources. The transformation of the Riegos del Alto Aragón area (RAA), mainly during the second half of the 20th century, was subject to major problems during the 1960s and 1970s, including monoculture of poorly productive winter cereals, water wastage, and soil degradation. Since the 1990s the RAA has been affected by modernization involving: (i) a change in the mode of irrigation, from gravity to sprinkler systems; (ii) the concentration of plots to enlarge the size of irrigated fields; and (iii) the introduction of more productive and highly water-consuming crops (corn, lucerne, vegetables). These changes coincided with enlargement of the irrigated area, increasing water demand at a time of increasing water scarcity because of restriction on the construction of new large reservoirs and declining water resources, because of climate and land use changes. Addressing this major problem has required new strategies, specifically the construction of small reservoirs and water ponds within the irrigated area. The ponds increase water reserves and facilitate sprinkling irrigation by adding pressure to the system. However, this has involved a huge rise in electricity consumption, which has increased the cost of production.

Floods modify the natural dynamics of river environments and greatly affect urban areas, especially in mountain regions where flooding is frequent because of the precipitation characteristics and orographic configuration. In this study the vulnerability of the central sector of the Pyrenees to flood events was investigated using frequency analysis of daily flow and precipitation data for the period from 1940 to 2012 for the headwaters of the Aragón and Ésera rivers. The land use evolution over the past 60 years was also analyzed. The return periods showed that floods have not been exceptional, and the high flow frequency has been large and closely related to precipitation events. This, combined with a large increase in human occupation, particularly since the 1990s, of fluvial areas associated with the land use evolution since 1956, has increased exposure to flood risks.

Los ri´os modi can la dina´mica natural del ambiente uvial y afectan enormemente a las a´reas urbanas, especialmente en a´reas de montan~a donde las precipitaciones son frecuentes debido a las caracteri´sticas de la precipitacio´n y a la con guracio´n orogra´ ca. En este arti´culo se analiza la vulnerabilidad del sector central de los Pirineos a estos eventos, a trave´s de un ana´lisis de frecuencia de los datos de caudal y precipitacio´n diarios desde 1940 hasta 2012 en las cabeceras de los ri´os Arago´n y E´sera. Se analiza tambie´n la evolucio´n de los usos del suelo en los u´ltimos 60 an~os. Los periodos de retorno muestran que las inundaciones no son excepcionales y que la frecuencia de caudales elevados es alta y estrechamente relacionada con los eventos de precipitacio´n. Este hecho, combinado con un excepcional crecimiento de la ocupacio´n humana de las a´reas uviales (especialmente desde la de´cada de 1990) producida por la evolucio´n de los usos del suelo desde 1956, ha aumentado el riesgo actual de exposicio´n.

In this paper, three methods (Terrestrial Laser Scanner (TLS), terrestrial Structure from Motion photogrammetry (SfM) and aerial SfM photogrammetry with an Unmanned Aerial Vehicle (UAV)) were evaluated and compared to produce high resolution point clouds and Digital Elevation Models (DEMs) in a semiarid, complex badland area (Los Aguarales) with tourism activities. Geomorphological processes and dynamics were studied at different spatial scales. The preliminary results showed the possibilities of a multiscale approach, using various non-invasive techniques, to assess geomorphological processes. The high resolution of the point clouds, obtained with TLS and terrestrial SfM photogrammetry, allowed preliminary identification of numerous spatial details, although no relevant topographical changes were detected during a short, wet spring period (with rainfall of 200 mm). UAV images allowed work at larger scales (catchment), mapping piping features, and could be seen as a worthwhile tool for time-effective data acquisition from larger areas. The application of different technologies and a multiscale approach to generate high resolution DEMs is a useful technique when carrying out geomorphological studies in semiarid badland areas. However, long term studies will be necessary to verify the suitability of these techniques in such complex landscapes, and quantify topographical changes and erosion rates. Finally, the information obtained with these tools could be used to promote the study area as an interesting geomorphosite with opportunities for tourism.

Hydrological signatures are indices that help to describe the behavior of catchments. These indices can also be used to transfer information from gauged to ungauged catchments. In this study, different approaches were evaluated to determine volumetric runoff coefficients in 18 small/ medium experimental gauged catchments of the Iberian Peninsula and to fit runoff calculations based on precipitation data for gauged and ungauged catchments. Using data derived from 1962 events, rainfall-runoff relationships were characterized and compared in order to evaluate the various hydrological response patterns. Volumetric run off coefficients and cumulative runoff and precipitation ratios of the events that generated runoff (Rcum) minimized the root mean square error. A linear fit for the estimation of Rcum in ungauged catchments was based on mean annual precipitation, rates of infiltration, the fraction of forest-land use, and the catchment channel length. Despite high catchment heterogeneity, Rcum resulted in a suitable parameter to evaluate hydrological variability in rural gauged and ungauged catchments. In 50% of the catchments, the precipitation accounted for less than 50% of the runoff variation. Annual precipitation, antecedent rainfall, and base flow did not have a high significance in rainfall-runoff relationships, which illustrates the heterogeneity of hydrological responses. Our results highlight the need for signature characterizations of small/medium rural catchments because they are the sources of runoff and sediment discharge into rivers, and it is more economical and efficient to take action to mitigate runoff in rural locations.

The purpose of this research was to identify major drought events on the Spanish mainland between 1961 and 2014 by means of two drought indices, and analyze the spatial propagation of drought conditions. The indices applied were the standardized precipitation index (SPI) and the standardized evaporation precipitation index (SPEI). The first was calculated as standardized anomalies of precipitation at various temporal intervals, while the second examined the climatic balance normalized at monthly scale, incorporating the relationship between precipitation and the atmospheric water demand. The daily meteorological data from Spanish Meteorological Archives (AEMet) were used in performing the analyses. Within the framework of the DESEMON project, original data were converted into a high spatial resolution grid (1.1 km2) following exhaustive quality control. Values of both indices were calculated on a weekly scale and different timescales (12, 24 and 36 months). The results show that during the first half of the study period, the SPI usually returned a higher identification of drought areas, while the reverse was true from the 1990s, suggesting that the effect from atmospheric evaporative demand could have increased. The temporal propagation from 12- to 24-month and 36-month timescales analyzed in the paper seems to be a far from straightforward phenomenon that does not follow a simple rule of time lag, because events at different temporal scales can overlap in time and space. Spatially, the propagation of drought events affecting more than 25% of the total land indicates the existence of various spatial gradients of drought propagation, mostly east–west or west–east, but also north–south have been found. No generalized episodes were found with a radial pattern, i.e., from inland to the coast.

This study presents a new climatology of monthly temperature for mainland Spain (1951–2010), performed with the highest quality and spatially dense, up-to-date monthly temperature dataset available in the study area (MOTEDAS). Three different interpolation techniques were evaluated: the Local Weighted Linear Regression (LWLR), the Regression-Kriging (RK) and the Regression-Kriging with stepwise selection (RKS), a modification of RK. The performances of the different models were evaluated by the leave-one-out validation procedure, comparing the results from the models with the original data and calculating different error measurements. The three techniques performed better for Tmax than for Tmin, and for the cold, rather than warmer months, also at lower altitude than highland areas. The best results were achieved with LWLR applied for the first time on temperatures in the Spanish mainland. This method improved the accuracy of the temperature reconstruction with respect to RK and RKS. We present a collection of Tmax and Tmin monthly charts, using the same temperature legend to prevent any visual bias in the interpretation of the results. The dataset is available upon request.

In this article, we approached the study of spatiotemporal variation in trends for the monthly mean values of maximum and minimum temperatures on the Spanish mainland between 1951 and 2010, in order to find out how length and selected periods affected trends. The trend and significance signals were calculated every month and for each cell individually, in a high spatial resolution grid (Mann–Kendall test) by using decreasing and increasing temporal windows (from 20 to 60 years and vice versa). Finally, the results are presented as a sequence of temporal window trend maps to show the spatiotemporal variability of trends at high resolution over the years. The results of increasing temporal window trends show that temperatures have increased overall on the Spanish mainland, but the impact is different for cold and warm months, maximum and minimum temperatures, and the area affected by significant trends varies depending on the month. The positive and significant trend affecting >20% of the total area extends in a west–east gradient during the cold months, while the reverse is true for the warmest ones. The analyses from decreasing the length of moving windows also vary greatly among months. The areas affected by significant trends are highly variable month-on-month, differ for maximum and minimum temperatures, and evolve in different ways over time. Few months show a significant trend during the last 30 years, and spatial distribution differences among trends for the maximum and minimum temperatures are detected. Spatially, a more complex gradient can be observed, but the global east–west and west–east gradient can also be generally seen in the warmest or coldest months. These findings show that a selected period determines the final trend. Furthermore, the results suggest that recent warming processes on the Spanish mainland have high spatial variability that differs among months and maximum and minimum temperatures, and has not been constant.

Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. We investigated the relationships between synoptic atmospheric patterns (i.e. weather types, WTs) and runoff, erosion and sediment yield throughout the Mediterranean basin by analyzing a large database of natural rainfall events at 68 research sites in 9 countries. Principal Component Analysis (PCA) was used to identify spatial relationships of the different WTs including three hydro-sedimentary variables: rainfall, runoff, and sediment yield (SY, used to refer to both soil erosion measured at plot scale and sediment yield registered at catchment scale). The results indicated 4 spatial classes of rainfall and runoff: (a) northern sites dependent on North (N) and North West (NW) flows; (b) eastern sites dependent on E and NE flows; (c) southern sites dependent on S and SE flows; and, finally, (d) western sites dependent on W and SW flows. Conversely, three spatial classes are identified for SY characterized by: (a) N and NE flows in northern sites (b) E flows in eastern sites, and (c) W and SW flows in western sites. Most of the rainfall, runoff and SY occurred during a small number of daily events, and just a few WTs accounted for large percentages of the total. Our results confirm that characterization by WT improves understanding of the general conditions under which runoff and SY occur, and provides useful information for understanding the spatial variability of runoff, and SY throughout the Mediterranean basin. The approach used here could be useful to aid of the design of regional water management and soil conservation measures.

Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. The results indicate two different temporal patterns: the first weather type exhibits (during the cold period: autumn and winter) westerly flows that produce the highest rainfall, runoff, and sediment yield values throughout the territory; the second weather type exhibits easterly flows that predominate during the warm period (spring and summer) and it is located on the Mediterranean coast of the Iberian Peninsula. However, the cyclonic situations present high frequency throughout the whole year with a large influence extended around the western Mediterranean basin. Contrary, the anticyclonic situations, despite of its high frequency, do not contribute significantly to the total rainfall, runoff, and sediment (showing the lowest efficiency) because of atmospheric stability that currently characterize this atmospheric pattern. Our approach helps to better understand the relationship of WTs on the seasonal and spatial variability of rainfall, runoff and sediment yield with a regional scale based on the large dataset and number of soil erosion experimental stations.

The analysis of monthly air temperature trends over mainland Spain during 1916–2015 shows that warming has not been constant over time nor generalized among different months; it has not been synchronous for maximum and minimum air temperatures; and it has been heterogeneous in space. Temperature rose during two characteristic pulses separated by a pause around the middle of the 20th century in some months. In other months, only the second rising period is identified, or no warming can be found. In all months, and both for maximum and minimum air temperatures, a stagnation of the increasing trend is observed in the last two decades of the study period. High spatial variability exists in trend signal and significance, and two contrasting temporal patterns of advance over the study area are identified for maximum and minimum air temperatures. These patterns can be related to prevalent flow directions and relief disposition with respect to the flows associated with low-variability meteorological patterns North Atlantic Oscillation (NAO) and Western Mediterranean Oscillation (WEMO). The results show that warming is a complex phenomenon at regional and sub-regional scales that can only be analysed using high-spatial-resolution data and considering global and local factors.

Hydrological signatures are indices that help to describe the behavior of catchments. These indices can also be used to transfer information from gauged to ungauged catchments. In this study, different approaches were evaluated to determine volumetric runoff coefficients in 18 small/ medium experimental gauged catchments of the Iberian Peninsula and to fit runoff calculations based on precipitation data for gauged and ungauged catchments. Using data derived from 1962 events, rainfall-runoff relationships were characterized and compared in order to evaluate the various hydrological response patterns. Volumetric runoff coefficients and cumulative runoff and precipitation ratios of the events that generated runoff (Rcum) minimized the root mean square error. A linear fit for the estimation of Rcum in ungauged atchments was based on mean annual precipitation, rates of infiltration, the fraction of forest-land use, and the catchment channel length. Despite high catchment heterogeneity, Rcum resulted in a suitable parameter to evaluate hydrological variability in rural gauged and ungauged catchments. In 50% of the catchments, the precipitation accounted for less than 50% of the runoff variation. Annual precipitation, antecedent rainfall, and base flow did not have a high significance in rainfall-runoff relationships, which illustrates the heterogeneity of hydrological responses. Our results highlight the need for signature characterizations
of small/medium rural catchments because they are the sources of runoff and sediment discharge into rivers, and it is more economical
and efficient to take action to mitigate runoff in rural locations., This research was supported by the
research projects CGL2015-64284-C2-2-R, CGL2015-64284-C2-1-R,
CGL2014-52135-C3-3-R, CGL2015-65569-R, CGL2014-56907-R, and
AGL2015-65036-C3-1 funded by the MINECO-FEDER (Spanish Ministry of
Economy and Competitiveness). E.N.-R. is the beneficiary of a Ramón y Cajal
postdoctoral contract (Spanish Ministry of Economy and Competitiveness).

Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. The results indicate two different temporal patterns: the first weather type exhibits (during the cold period: autumn and winter) westerly flows that produce the highest rainfall, runoff, and sediment yield values throughout the territory; the second weather type exhibits easterly flows that predominate during the warm period (spring and summer) and it is located on the Mediterranean coast of the Iberian Peninsula. However, the cyclonic situations present high frequency throughout the whole year with a large influence extended around the western Mediterranean basin. Contrary, the anticyclonic situations, despite of its high frequency, do not contribute significantly to the total rainfall, runoff, and sediment (showing the lowest efficiency) because of atmospheric stability that currently characterize this atmospheric pattern. Our approach helps to better understand the relationship of WTs on the seasonal and spatial variability of rainfall, runoff and sediment yield with a regional scale based on the large dataset and number of soil erosion experimental stations., Spanish Government (Ministry of Economy and Competitiveness, MINECO) and FEDER Projects: CGL2014 52135-C3-3-R, ESP2017-89463-C3-3-R, CGL2014-59946-R, CGL2015-65569-R, CGL2015-64284-C2-2-R, CGL2015-64284-C2-1-R, CGL2016-78075-P, GL2008-02879/BTE, LEDDRA 243857, RECARE-FP7, CGL2017-83866-C3-1-R, and PCIN-2017-061/AEI. Dhais Peña-Angulo received a 'Juan de la Cierva' postdoctoral contract (FJCI-2017-33652 Spanish Ministry of Economy and Competitiveness, MEC). Ana Lucia acknowledge the 'Brigitte-Schlieben-Lange-Programm'. The 'Geoenvironmental Processes and Global Change' (E02_17R) was financed by the Aragón Government and the European Social Fund. José Andrés López-Tarazón acknowledges the Secretariat for Universities and Research of the Department of the Economy and Knowledge of the Autonomous Government of Catalonia for supporting the Consolidated Research Group 2014 SGR 645 (RIUS-Fluvial Dynamics Research Group). Artemi Cerdá thank the funding of the OCDE TAD/CRP JA00088807. José Martínez-Fernández acknowledges the project Unidad de Excelencia CLU-2018-04 co-funded by FEDER and Castilla y León Government. Ane Zabaleta is supported by the Hydro-Environmental Processes consolidated research group (IT1029-16, Basque Government). This paper has the benefit of the Lab and Field Data Pool created within the framework of the COST action CONNECTEUR (ES1306). This research was supported by projects funded by Spanish and FEDER, the 'Brigitte-Schlieben-Lange-Programm'; the Governments of Spanish Autonomous Region of Aragón, Catalonia, Castilla-León and Basque Country. José Andrés López-Tarazón acknowledges the Secretariat for Universities and Research of the Department of the Economy and Knowledge of the Autonomous Government of Catalonia for supporting the Consolidated Research Group 2014 SGR 645 (RIUS-Fluvial Dynamics Research Group). Artemi Cerdá thank the funding of the OCDE TAD/CRP JA00088807. José Martínez-Fernández acknowledges the project Unidad de Excelencia CLU-2018-04 co-funded by FEDER and Castilla y León Government. Ane Zabaleta is supported by the Hydro-Environmental Processes consolidated research group (IT1029-16, Basque Government). This paper has the benefit of the Lab and Field Data Pool created within the framework of the COST action CONNECTEUR (ES1306).