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13 pages, 4 figures, 3 tables. ; [EN] The aim of this study was to determine the spatial distribution of rainfall erosivity in a 504 km2 river basin in Eastern Pyrenees and assess its uncertainties. The study area is topographically complex and is dominated by Mediterranean climate with intense rains during summer. Available rainfall dataset includes 14 years spanning from 1991 to 2004 at daily resolution from seven weather stations and sub-hourly from one station. Daily R values were calculated from sub-hourly data, and then by using the relationship between daily R values and precipitation, the R values for weather stations having only daily rainfall resolution were calculated. The error propagation by using such upscaling approach was analyzed. The studied sources of uncertainty of R factor at annual scale were: the use of the relationship between daily R values and precipitation, the temporal averaging of R values and spatial variation. Results have shown that at annual scale the temporal averaging was the largest contributor of uncertainty (70%); however this contribution decreased significantly (14%) when R was estimated for the long term. ; [ES] El objetivo de este estudio fue determinar la distribución espacial de la erosividad de precipitación en una cuenca de 504 km2 en el Este de los Pirineos y evaluar sus incertidumbres. El área de estudio presenta una topografía compleja y está dominada por un clima Mediterráneo con lluvias intensas durante el verano. Los datos de precipitación utilizados abarcan 14 años, desde 1991 hasta 2004, a una resolución diaria en siete estaciones meteorológicas y minutal en una estación. Los valores diarios de R se calcularon a partir de datos con resolución minutal, y luego se estableció una relación entre valores diarios de R y precipitación, con el fin de calcular los valores de R para las estaciones meteorológicas que sólo presentan resolución diaria. Las fuentes de incertidumbre considerados para el factor R a escala anual fueron: el uso de la relación entre los valores de R diaria y precipitación, el promedio temporal de los valores de R y la variación espacial. Los resultados han mostrado que a escala anual la variación temporal fue el mayor contribuyente (70%) a la incertidumbre total, sin embargo éste disminuyó significativamente (14%) cuando R fue estimada a largo plazo. ; This research was supported by the PROBASE (CGL2006-11619). The authors are indebted to: Montserrat Soler and Juliana Delgado and the other members of the Surface Hydrology and Erosion Research Group at IDAEA, CSIC for providing the necessary data and support. The contribution of the first author was made possible by a DEBEQ grant, funded by the Autonomous Government of Catalonia. Research at the Vallcebre area is also supported by an agreement between CSIC and the Ministerio de Medio Ambiente, Medio Rural y Marino (RESEL). ; Peer reviewed

The diverse sources of uncertainty associated with the calculation of rainfall kinetic energy and rainfall erosivity, calculated from precipitation data, were investigated at a range of temporal and spatial scales in a mountainous river basin (504 km2) in the south-eastern Pyrenees. The sources of uncertainty analysed included both methodological and local sources of uncertainty and were (i) tipping-bucket rainfall gauge instrumental errors, (ii) the efficiency of the customary equation used to derive rainfall kinetic energy from intensity, (iii) the efficiency of the regressions obtained between daily precipitation and rainfall erosivity, (iv) the temporal variability of annual rainfall erosivity values, and the spatial variability of (v) annual rainfall erosivity values and (vi) long-term erosivity values. The differentiation between systematic (accuracy) and random (precision) errors was taken into account in diverse steps of the analysis. The results showed that the uncertainty associated with the calculation of rainfall kinetic energy from rainfall intensity at the event and station scales was as high as 30%, because of insufficient information on rainfall drop size distribution. This methodological limitation must be taken into account for experimental or modelling purposes when rainfall kinetic energy is derived solely from rainfall intensity data. For longer temporal scales, the relevance of this source of uncertainty remained high if low variability in the types of rain was supposed. Temporal variability of precipitation at wider spatial scales was the main source of uncertainty when rainfall erosivity was calculated on an annual basis, whereas the uncertainty associated with long-term erosivity was rather low and less important than the uncertainty associated with other model factors such as those in the RUSLE, when operationally used for long-term soil erosion modelling. © 2011 Author(s). ; The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2011) under grant agreement 211732 (MIRAGE project). The PROBASE (CGL2006-11619/HID) and MONTES (CSD2008-00040) projects, funded by the Spanish Government, also contributed to its development. Research at the Vallcebre catchments is also supported by the agreement (RESEL) between the CSIC and the "Ministerio de Medio Ambiente y Medio Rural y Marino" (Environment Ministry). The contribution of G. Catari was made possible by a DEBEQ grant, funded by the Autonomous Government of Catalonia. J. Latrón was the beneficiary of a research contract (Ramón y Cajal programme) funded by the "Ministerio de Ciencia e Innovación" (Science Ministry). ; Peer Reviewed

The sources of uncertainty associated with the calculation of rainfall kinetic energy and rainfall erosivity were investigated when the USLE R factor was operationally calculated for a mountainous river basin (504 km2) in the Southeastern Pyrenees. Rainfall kinetic energy was first obtained at the scale of the rainfall event by means of sub-hourly precipitation tipping-bucket rain gauge records and updates of the Kinnell (1981) equation. Annual erosivity values for the nearby pluviometric stations were then derived from the linear regressions between daily rainfall erosivity and daily precipitation, obtained for two different seasons. Finally, maps for rainfall erosivity estimates were obtained from the station values with Thiessen polygons. The sources of uncertainty analysed were i) the tipping-bucket instrumental errors, ii) the efficiency of the Kinnell (1981) equation, iii) the efficiency of the regressions between daily precipitation and kinetic energy, iv) the temporal variability of annual rainfall erosivity values, and the spatial variability of v) annual rainfall erosivity values and vi) long-term R factor values. The results showed that the uncertainty associated with the calculation of rainfall kinetic energy from rainfall intensity at the event and station scales is highly relevant and must be taken into account for experimental or modelling purposes; for longer temporal scales, the relevance of this source of uncertainty remains high if there is a low variability of the types of rain. Temporal variability of precipitation at wider spatial scales is the main source of uncertainty when rainfall erosivity is to be calculated on an annual basis, whereas the uncertainty associated with the long-term R factor is rather low and less important than the uncertainty associated with the other RUSLE factors when operationally used for long-term soil erosion modelling. © Author(s) 2010. ; The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2011) under grant agreement 211732 (MIRAGE project). The PROBASE (CGL2006-11619/HID) and MONTES (CSD2008-00040) projects, funded by the Spanish Government, also contributed to its development. Research at the Vallcebre catchments is also supported by the agreement (RESEL) between the CSIC and the "Ministerio de Medio Ambiente y Medio Rural y Marino" (Environment Ministry). The contribution of G. Catari was made possible by a DEBEQ grant, funded by the Autonomous Government of Catalonia. J. Latron was the beneficiary of a research contract (Ram´on y Cajal programme) funded by the "Ministerio de Ciencia e Innovaci´on" (Science Ministry). ; Peer Reviewed

The Vallcebre catchments are located in a middle mountain area of the Pyrenean ranges, built up by sedimentary rocks and loamy soils. The vegetation cover is pastures and forests of Pinus sylvestris, mostly occupying former agricultural terraces. Some relatively small, heavily eroded landscapes (badlands) occur in the catchments, playing a relevant hydrological and geomorphic role. Annual precipitation is 924 mm and potential (reference) evapotranspiration is about 700 mm. Rainfall interception in forests represents about 24% of precipitation; interception rates were similar throughout the seasons because of a compensation between rainfall intensities and atmospheric conditions. Soil moisture showed a temporal pattern characterised by the occurrence of marked deficit periods in summer and also, but less pronounced, in winter. During most of the year, subsurface flows on hillslopes drove the spatial organisation of soil moisture and the occurrence of saturated areas. Nevertheless, this spatial organisation was also controlled by the patterns of vegetation cover. During dry periods, subsurface flow ceased, saturated areas disappeared and the spatial patterns of soil moisture changed. Stream flow from these catchments was dominated by storm flow, and the runoff generating mechanisms showed a clear seasonal pattern, controlled mainly by the soil moisture and the extent of saturated areas. During the dry periods, runoff was produced only on impervious areas and badlands. At the end of the dry periods, some large rainfall events generated significant runoff because of the perched saturation of the shallow soil horizons. Thereafter, runoff generation was dominated by the role of saturated areas. Stream waters in catchments with badlands had very high suspended sediment concentrations. The seasonal pattern of erosion processes in badlands was characterised by physical weathering during winter, regolith breakdown and vigorous hillslope erosion during spring and summer, and efficient transport of sediments in autumn. ; This research was supported by the projects VAHMPIRE (ENV4-CT95-0134) funded by the European Commission and EPROHIDRO (HID98-1056-C02-01) funded by the Programa Nacional de Recursos Hídricos, Spanish Government. The Vallcebre catchments also operate with support from the RESEL network, through an agreement between CSIC and DGCONA. ; Peer Reviewed

Gallart Gallego, Francesc et al. ; Temporary streams are those water courses that undergo the recurrent cessation of flow or the complete drying of their channel. The structure and composition of biological communities in temporary stream reaches are strongly dependent on the temporal changes of the aquatic habitats determined by the hydrological conditions. Therefore, the structural and functional characteristics of aquatic fauna to assess the ecological quality of a temporary stream reach cannot be used without taking into account the controls imposed by the hydrological regime. This paper develops methods for analysing temporary streams' aquatic regimes, based on the definition of six aquatic states that summarize the transient sets of mesohabitats occurring on a given reach at a particular moment, depending on the hydrological conditions: Hyperrheic, Eurheic, Oligorheic, Arheic, Hyporheic and Edaphic. When the hydrological conditions lead to a change in the aquatic state, the structure and composition of the aquatic community changes according to the new set of available habitats. We used the water discharge records from gauging stations or simulations with rainfall-runoff models to infer the temporal patterns of occurrence of these states in the Aquatic States Frequency Graph we developed. The visual analysis of this graph is complemented by the development of two metrics which describe the permanence of flow and the seasonal predictability of zero flow periods. Finally, a classification of temporary streams in four aquatic regimes in terms of their influence over the development of aquatic life is updated from the existing classifications, with stream aquatic regimes defined as Permanent, Temporary-pools, Temporary-dry and Episodic. While aquatic regimes describe the long-term overall variability of the hydrological conditions of the river section and have been used for many years by hydrologists and ecologists, aquatic states describe the availability of mesohabitats in given periods that determine the presence of different biotic assemblages. This novel concept links hydrological and ecological conditions in a unique way. All these methods were implemented with data from eight temporary streams around the Mediterranean within the MIRAGE project. Their application was a precondition to assessing the ecological quality of these streams. ; The research leading to these results received funding from the European Community's Seventh Framework Programme (FP7/2007-2011) under grant agreement 211732 (MIRAGE project), as well from the Spanish Government under the RespHimed project (CGL2010-18374) and a research contract (Ram´on y Cajal programme) granted to J. Latron. ; Peer Reviewed

Gallart Gallego, Francesc et al. ; Temporary streams are those water courses that undergo the recurrent cessation of flow or the complete drying of their channel. The biological communities in temporary stream reaches are strongly dependent on the temporal changes of the aquatic habitats determined by the hydrological conditions. The use of the aquatic fauna structural and functional characteristics to assess the ecological quality of a temporary stream reach can not therefore be made without taking into account the controls imposed by the hydrological regime. This paper develops some methods for analysing temporary streams' aquatic regimes, based on the definition of six aquatic states that summarize the sets of mesohabitats occurring on a given reach at a particular moment, depending on the hydrological conditions: flood, riffles, connected, pools, dry and arid. We used the water discharge records from gauging stations or simulations using rainfall-runoff models to infer the temporal patterns of occurrence of these states using the developed aquatic states frequency graph. The visual analysis of this graph is complemented by the development of two metrics based on the permanence of flow and the seasonal predictability of zero flow periods. Finally, a classification of the aquatic regimes of temporary streams in terms of their influence over the development of aquatic life is put forward, defining Permanent, Temporary-pools, Temporary-dry and Episodic regime types. All these methods were tested with data from eight temporary streams around the Mediterranean from MIRAGE project and its application was a precondition to assess the ecological quality of these streams using the current methods prescribed in the European Water Framework Directive for macroinvertebrate communities. © Author(s) 2011. ; The research leading to these results received funding from the European Community's Seventh Framework Programme (FP7/2007-2011) under grant agreement 211732 (MIRAGE project), as well from the Spanish Government under the RespHimed project (CGL2010-18374) and a research contract (Ram´on y Cajal programme) granted to J. Latron. ; Peer Reviewed

Temporary rivers are characterized by shifting habitats between flowing, isolated pools, and dry phases. Despite the fact that temporary rivers are currently receiving increasing attention by researchers and managers, the isolated pools phase has been largely disregarded. However, isolated pools in temporary rivers are transitional habitats of major ecological relevance as they support aquatic ecosystems during no-flow periods, and can act as refugees for maintaining local and regional freshwater biodiversity. Pool characteristics such as surface water permanence and size, presence of predators, local physicochemical conditions, time since disconnection from the river flow, or distance to other freshwater habitats challenge a comprehensive understanding of the ecology of these habitats, and challenge ecological quality assessments and conservation practices in temporary rivers. In this paper, we aim at providing a characterization of isolated pools from a hydrological, geomorphological, physicochemical, biogeochemical, and biological point of view as a framework to better conceptualize, conserve, and manage these habitats ; This paper was supported by the by the MECODISPER project (CTM2017-89295-P) funded by the Spanish Ministerio de Economía, Industria y Competitividad (MINECO)—Agencia Estatal de Investigación (AEI) and co-funded by the European Regional Development Fund (ERDF), the TRivers-P project (ACA210/18/00022) funded by the Catalan Water Agency, and the RHYSOTTO project (PID2019-106583RB-I00) funded by the Spanish Ministerio de Ciencia e Innovación. N.B. and D.v.S. are Serra Húnter Fellows. N.C. was supported by the French research program Make Our Planet Great Again (MOPGA). D.v.S. was supported by the project PURIFY (ACRP10-PURIFY-KR17AC0K13643) funded by the Austrian Government. The FEHM (Freshwater Ecology, Hydrology and Management) research group is funded by the "Agència de Gestió d'Ajuts Universitaris i de Recerca" (AGAUR) at the "Generalitat de Catalunya" (2017SGR1643). ; Peer reviewed

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).