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In forested areas, canopies play an important role in the partitioning of rainfall. During this process there is also a redistribution of particulate matter (PM) that is deposited from the atmosphere on vegetative surfaces and transported to soil layers by throughfall and stemflow. We collected samples of rainfall, throughfall, and stemflow from two different forest plots (pine and oak) in a Mediterranean mountainous area and analyzed the amount and size distributions of PM (0.45 μm < PM < 500 μm). The exploration of backward trajectories revealed that PM content varied significantly. This depended on the origin of the air mass, with Atlantic fronts transporting less PM in the atmosphere than North African dust intrusions, which added disproportionate inputs of PM. Overall, throughfall provided the largest proportion of incoming PM under trees, but, at the base of each tree, stemflow led to a localized input of water that was more PM enriched than water through open precipitation or throughfall. Interspecific differences in PM fluxes were noted with pines retaining more PM in their crowns than oaks. Furthermore, the presence of leaves on oak increased the size and the amount of particulates released by throughfall. The PM in stemflow was smaller and rounder than in throughfall. This study adds to our understanding knowledge of the processes that control the deposition and distribution of PM delivered to forest soils, a fraction that is often ignored in studies of nutrient and energy fluxes in ecosystems. ©2019. American Geophysical Union. All Rights Reserved., This research was supported by the projects TransHyMed (CGL2016‐75957‐R AEI/FEDER, UE) and MASCC‐DYNAMITE (PCIN‐2017‐061/AEI) funded by the “Agencia Estatal de Investigación”. C. Cayuela was the beneficiary of a predoctoral FPI grant (BES‐2014‐070609) and a predoctoral mobility grant (EEBB‐I‐16‐11510), both funded by the Spanish Ministry of Economy and Competitiveness. P. Llorens was the beneficiary of (PRX15/00326) funding from the Spanish Ministry of Education, Culture and Sport for professors and senior researchers working in foreign universities and research centers. Support provided by the members of the Bioimaging center of the University of Delaware is gratefully acknowledged. We are grateful too to the members of the Surface Hydrology and Erosion group of the IDAEA‐CSIC, especially Elisenda Sánchez‐Costa for her help during fieldwork and Jordi Bellés for his assistance in the laboratory. Finally, we want to thank Michael Eaude for reviewing the English. Data can be download from the DIGITAL.CSIC repository http://hdl.handle.net/10261/176564 in Cayuela et al. (2019).

Traditional cultivation terraces are one of the most ancient and conspicuous agricultural landscapes in mountain and hilly regions of the Mediterranean basin. Spreading out from Asia, the first terraces in the Mediterranean region date from the Bronze Age and the classical Hellenic and Roman periods, reaching their greatest spatial extent during the eighteenth and nineteenth centuries. Under optimum management, these systems contribute to the conservation of soil and water resources by increasing infiltration and decreasing sediment yield. However, traditional management and cultivation ceased on many terraced landscapes of the northern-shore Mediterranean countries during the twentieth century, with variable results. An extensive bibliographic review and meta-analysis was carried out to explore the main effects of land abandonment of Mediterranean agricultural terraces on local hydrological and geomorphological processes. Our results point to the development of vegetation cover and degradation of terraced structures (e.g., walls, terrace risers, channels) as the main critical factors controlling the hydrological behaviour (i.e., runoff production and hydrological connectivity) of abandoned terrace systems. Severe geomorphological problems, in the form of intense surface erosion, aggressive piping and gullying, occurred under special climatic (semi-arid climate), lithologic (dispersive marls) and structural (high vertical hydraulic gradient) conditions. Dense colonization by vegetation proved to be of major importance for controlling surface erosion. Vegetation, however, showed a limited capacity to control the activity of mass movements in most cases. Mass movements in the form of small soil slips primarily affected long-abandoned terraces in hillslope concavities and valley bottom positions that concentrate (surface and subsurface) water fluxes and show recurrent soil saturation. In humid terraced landscapes characterized by high hillslope gradients and terrace risers, the most devastating effects of mass movements took place in the form of debris slips and terrace cascading landslides triggered by extreme rainfall. A variety of management options (non-intervention, stewardship of natural rewilding processes and active rehabilitation) can be applied, depending on vegetation development potential, site hydro-geomorphic vulnerability and local socio-economic interests. Effective conservation approaches will be required to preserve the environmental, socio-cultural and historical values of these ancient anthropogenic landscapes. © 2019 Elsevier B.V., This study is supported by the MASCC project funded by the European Union 7th Framework Programme (ARIMNet2, grant agreement 618127) and by the MASCC-DYNAMITE (PCIN-2017-061/AEI), TransHyMed (CGL2016-75957-R, AEI/FEDER, EU) and ESPAS (CGL2015-65569-R) projects funded by the State Research Agency (AEI) of the Spanish Ministry of Science, Innovation and Universities (MCIU) and the Spanish Ministry of Economy and Competitiveness (MEC). Mariano Moreno-de-las-Heras is beneficiary of a Juan de la Cierva fellowship (IJCI-2015-26463) funded by the MEC. We are grateful to Jean Claude Latombe, José Angel Llorente, Manuel López-Vicente and Ruth Manfredi, who kindly provided photographs of terraced landscapes and erosive processes for this study. We also thank the Editor, Scott A. Lecce, and four anonymous reviewers for their thoughtful comments, as well as Michael Eaude for language corrections.

Obtaining representative hydrometric values is essential for characterizing extreme events, hydrological dynamics and detecting possible changes on the long-term hydrology. Reliability of streamflow data requires a temporal continuity and a maintenance of the gauging stations, which data are affected by epistemic and random sources of error. An assessment of discharge meterings' and stage-discharge rating curves' uncertainties were carried out by comparing the accuracy of the measuring instruments of two different hydrometric networks (i.e., one analogical and one digital) established in the same river location at the Mediterranean island of Mallorca. Furthermore, the effects of such uncertainties were assessed on the hydrological dynamics, considering the significant global change impacts beset this island. Evaluation was developed at four representative gauging stations of the hydrographic network with analogic (≈40 years) and digital (≈10 years) data series. The study revealed that the largest source of uncertainty in the analogical (28 to 274%) and in the digital (17–37%) networks were the stage-discharge rating curves. Their impact on the water resources was also evaluated at the event and annual scales, resulting in an average difference of water yields of 183% and 142% respectively. Such improvement on the comprehension of hydrometric networks uncertainties will dramatically benefit the interpretation of the long-term streamflow by providing better insights into the hydrologic and flood hazard planning, management and modelling. © 2019, This work was supported by a research contract funded in 2014 by the Directorate-General of Water Resources (Department of Environment, Agriculture, and Fishery of the Balearic Autonomous Government) and the research project CGL2012-32446 “Assessing hydrological and sediment connectivity in contrasting Mediterranean catchments. Impacts of Global Change-MEDhyCON” funded by the Ministry of Economy and Competitiveness of the Spanish Government. The contribution of Jérôme Latron was supported by the research project PCIN-2017-061/AEI also funded by the Ministry of Economy and Competitiveness of the Spanish Government. Josep Fortesa has a contract funded by Ministry of Innovation, Research and Tourism of the Autonomous Government of the Balearic Islands (FPI/2048/2017). He also acknowledges the support from “la Caixa” Foundation through a mobility grant for young researchers at the Universitat de les Illes Balears with announcement reference number 3111. Julián García-Comendador is in receipt of a pre-doctoral contract (FPU15/05239) funded by the Spanish Ministry of Education and Culture. Aleix Calsamiglia acknowledges the support from the Spanish Ministry of Economy and Competitiveness through a pre-doctoral contract (BES-2013-062887). José Andrés López-Tarazón is in receipt of a Vicenç Mut postdoctoral fellowship (CAIB PD/038/2016) funded by the Vice-presidency and Ministry of Innovation, Research and Tourism of the Autonomous Government of the Balearic Islands. Meteorological data were facilitated by the Spanish Meteorological Agency (AEMET). Authors thank the three anonymous reviewers and the Guest Editor, Prof. Axel Bronstert, for their constructive comments and suggestions that significantly improved the final version of the paper.

Recent virtual and experimental investigations have shown that the young water fraction Fyw (i.e. the proportion of catchment outflow younger than circa 2–3 months) increases with discharge in most catchments. The discharge sensitivity of Fyw has been defined as the rate of increase in Fyw with increasing discharge (Q), and has been estimated by the linear regression slope between Fyw and Q, hereafter called DS(Q). The combined use of both metrics, Fyw and DS(Q), provides a promising method for catchment inter-comparison studies that seek to understand streamflow generation processes. Here we explore the discharge sensitivity of Fyw in the intensively sampled small Mediterranean research catchment Can Vila. Intensive sampling of high flows at Can Vila allows young water fractions to be estimated for the far upper tail of the flow frequency distribution. These young water fractions converge toward 1 at the highest flows, illustrating a conceptual limitation in the linear regression method for estimating DS(Q) as a metric of discharge sensitivity: Fyw cannot grow with discharge indefinitely, since the fraction of young water in discharge can never be larger than 1. Here we propose to quantify discharge sensitivity by the parameter of an exponential-type equation expressing how Fyw varies with discharge. The exponential parameter (Sd) approximates DS(Q) at moderate discharges where Fyw is well below 1; however, the exponential equation and its discharge sensitivity metric better capture the non-linear relationship between Fyw and Q and are robust with respect to changes in the range of sampled discharges, allowing comparisons between catchments with strongly contrasting flow regimes., Hydrology and Earth System Sciences Discussions, ISSN:1812-2116, ISSN:1812-2108

The young water fraction (Fyw), the proportion of water younger than 2-3 months, was investigated in soil-, ground- and stream waters in the 0.56 Km2 sub-humid Mediterranean Can Vila catchment. Rain water was sampled at 5-mm rainfall intervals. Mobile soil water and groundwater were sampled fortnightly, using suction lysimeters and two shallow wells, respectively. Stream water was dynamically sampled at variable time intervals (30 minutes to 1 week), depending on flow. A total of 1,529 18O determinations obtained during 58 months were used. The usual hypothesis of rapid evapotranspiration of summer rainfall could not be maintained, leading to discard the use of an “effective precipitation” model. Soil mobile waters had Fyw up to 34%, while in ground and stream were strongly related to water table and discharge variations, respectively. In stream waters, due to the highly skewed flow duration curve, the flow-averaged young water fraction (F*yw) was 22.6%, whereas the time-averaged Fyw was 6.2%. Nevertheless, both F*yw and its exponential discharge sensitivity (Sd) showed relevant changes when different 12-month sampling periods were investigated. The availability of Sd and a detailed flow record allowed us to simulate the young water fraction that would be obtained with a virtual thorough sampling (F**yw). This showed that underestimation of F*yw is associated with missing the sampling of highest discharges and revealed underestimations of F*yw by 25% for the dynamic sampling and 66% for the weekly sampling. These results confirm that the young water fraction and its discharge sensitivity are metrics that depend more on precipitation forcing than on physiographic characteristics, so the comparisons between catchments should be based on mean annual values and inter-annual variability. They also support the dependence of the young water fraction on the sampling rate and show the advantages of flow-weighted F*yw. Water age investigations should be accompanied by the analysis of flow duration curves. In addition, the simulation of F**yw is proposed as a method for checking the adequacy of the sampling rate used., This research was supported by the projects TransHyMed (CGL2016‐75957‐ R AEI/FEDER, UE) and MASCC‐ DYNAMITE (PCIN‐2017‐061/AEI) funded by the Spanish Ministerio de Ciencia, Innovación y Universidades, as well as the grant SGR 2017 1643 funded by the Generalitat de Catalunya. C. Cayuela was the beneficiary of a predoctoral FPI grant (BES‐2014‐070609) funded by the Spanish Ministry of Economy and Competitiveness and the contribution by M. Sprenger was supported by the Deutsche Forschungsgemeinschaft (project no. 397306994). We are grateful to G. Bertran, M. Roig-Planasdemunt and E. Sánchez for their support during field work at the Can Vila catchment, to J. Kirchner, J. von Freyberg and K. Beven for their comments, as well as to M. Eaude for his English style improvements.

Ecosystems experience natural disturbances and anthropogenic impacts that affect biological communities and ecological processes. When natural disturbance modifies anthropogenic impacts, current widely used bioassessment metrics can prevent accurate assessment of biological quality. Our aim was to assess the ability of biomonitoring metrics to detect anthropogenic impacts at both perennial and intermittent sites, and in the latter including both flowing and disconnected pool aquatic phases. Specifically, aquatic macroinvertebrates from 20 rivers were sampled along gradients of natural flow intermittence (natural disturbance) and anthropogenic impacts to investigate their combined effects on widely used river biomonitoring metrics (i.e. taxonomic richness and standard biological indices) and novel functional metrics, including functional redundancy (i.e. the number of taxa contributing similarly to an ecosystem function, here a trophic function) and response diversity (i.e. how functionally similar taxa respond to natural disturbance and anthropogenic impacts). Only the widely used IBMWP index (Iberian Biological Monitoring Working Party) was able to detect anthropogenic impacts in intermittent rivers when used during flowing phases. Several functional metrics also detected anthropogenic impacts regardless of flow intermittence. Besides, functional redundancy of the entire community remained effective even in disconnected pools. Synthesis and applications . Our results show that natural flow intermittence can confound river bioassessment, and that a set of new functional metrics could be used as effective alternatives to standard metrics in naturally disturbed intermittent rivers. Our findings suggest that water managers should incorporate alternative functional metrics in the routine biomonitoring of naturally disturbed rivers., The study was supported by the LIFE+ TRivers (LIFE13 ENV/ES/000341) project. We acknowledge the contribution of FEHM lab members and students who participated in fieldwork. C.G.‐C. was supported by a “Juan de la Cierva‐Formación” research contract (MINECO, FJCI‐2015‐25785). We especially thank Rachel Stubbington for her supervision and useful suggestions that greatly improved the manuscript.

This study investigates moisture origin, characteristics and intra-event scale variability of the isotopic signature of rainfall in a Mediterranean mountain area, based on data from the Vallcebre Research Catchments, NE Spain. Weekly data and samples were used to analyse the general dynamics of the isotopic composition of precipitation and its relationship with meteorological variables at the sampling site. Then, based on the data and samples available at the intra-event scale, the variability of the isotopic signature during rainfall events was characterised and an explanation of what caused the observed variability was attempted. Results at the weekly time scale show that the maximum relative deviation of the heavy isotopic content with respect to Standard Mean Ocean Water (δ18O) of the precipitation signature occurred during summer months and, in contrast, the minimum during winter months. The intra-annual trend of rainfall δ18O roughly followed the mean monthly air temperature. Using intra-event information, three main types of δ18O isotopic trends were found during rainfall events: most of the events had a V-shaped isotopic trend, followed by L-shaped and constant trend events. Changes in moisture sources ’diagnosed using a Lagrangian approach and a previously existing contribution algorithm’ were one of the causes of the isotopic variability and changes at the intra-event scale, but these may also have been influenced by sub-cloud processes that modified the isotopic signature. Moisture sources for analysed events showed the main influence of the Mediterranean area, but also an important influence of the Atlantic Basin. © 2019 Elsevier B.V., This study derived from a first author internship in the Surface Hydrology and Erosion group at IDAEA-CSIC. Generous support from members of the group is acknowledged. The authors are grateful to the NOAA Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model and READY website ( http://www.ready.noaa.gov) used in this publication. This study was supported by the TransHyMed (CGL2016-75957-R AEI/FEDER, UE), MASCC-DYNAMITE (PCIN-2017-061/AEI), CGL2015-65627-C3-2-R (MINECO/FEDER) and CGL2016-81828-REDT (MINECO) and was performed in the framework of the HYdrological cycle in the Mediterranean EXperiment (HyMeX). The authors would also like to acknowledge the helpful and constructive suggestions and comments from three anonymous reviewers that have improved this study.

The isotopic composition of precipitation (D and 18O) has been widely used as an input signal in water tracer studies. Whereas much recent effort has been put into developing methodologies to improve our understanding and modelling of hydrological processes (e.g., transit-time distributions or young water fractions), less attention has been paid to the spatio-temporal variability of the isotopic composition of precipitation, used as input signal in these studies. Here, we investigated the uncertainty in isotope-based hydrograph separation due to the spatio-temporal variability of the isotopic composition of precipitation. The study was carried out in a Mediterranean headwater catchment (0.56 km2). Rainfall and throughfall samples were collected at three locations across this relatively small catchment, and stream water samples were collected at the outlet. Results showed that throughout an event, the spatial variability of the input signal had a higher impact on hydrograph separation results than its temporal variability. However, differences in isotope-based hydrograph separation determined preevent water due to the spatio-temporal variability were different between events and ranged between 1 and 14%. Based on catchment-scale isoscapes, the most representative sampling location could also be identified. This study confirms that even in small headwater catchments, spatio-temporal variability can be significant. Therefore, it is important to characterize this variability and identify the best sampling strategy to reduce the uncertainty in our understanding of catchment hydrological processes. © 2018 John Wiley & Sons, Ltd., This research was supported by the projects TransHyMed (CGL2016‐75957‐R AEI/FEDER, UE) and MASCC‐DYNAMITE (PCIN‐2017‐061/AEI). C. Cayuela was beneficiary of a predoctoral FPI grant (BES‐2014‐070609) and a predoctoral mobility grant (EEBB‐I‐17‐12493). We are grateful to G. Bertran, F. Gallart, A.J. Molina, M. Moreno de las Heras, and E. Sánchez‐Costa for their support during fieldwork and data analysis. We also thank all the members of the Northern Rivers Institute where part of this study was conceived. Finally, we want to thank M. Eaude for reviewing the English.

Soil water-content (SWC) variability in forest ecosystems is affected by complex interactions between climate, topography, forest structure and soil factors. However, detailed studies taking into account the combined effects of these factors are scarce. This study's main aims were to examine the control that throughfall exerts on local spatial variation of near-surface soil water-content and to combine this information with forest structure and soil characteristics, in order to analyze all their effects together. Two stands located in the Vallcebre Research Catchments (NE Spain) were studied: one dominated by Quercus pubescens and the other by Pinus sylvestris. Throughfall and the related shallow SWC were monitored in each plot in 20 selected locations. The main characteristics of the nearest tree and soil parameters were also measured. The results indicated that mean SWC increment at the rainfall event scale showed a strong linear relationship with mean throughfall amount in both forest plots. The % of locations with SWC increments increased in a similar way to throughfall amount in both forest plots. The analyses considering all the effects together indicated again that throughfall had a significant positive effect in both forest plots, while soil litter depth showed a significant negative effect for the oak plot but lower statistical significance for the pine plot, showing a comparable –although more erratic– influence of the organic forest floor for this plot. These results, together with lower responses of SWC to throughfall than expected in rainfall events characterized by low preceding soil water-condition and high rainfall intensity, suggest that litter layer is playing an important role in controlling the soil water-content dynamics. The biometric characteristics of the nearest trees showed significant but very weak relationships with soil water-content increment, suggesting that stemflow and throughfall may act at lower distances from tree trunk than those presented in our study. © 2018 Elsevier B.V., This research was supported by the projects TransHyMed (CGL2016-75957-R AEI/FEDER, UE) and MASCC-DYNAMITE (PCIN-2017-061/AEI) funded by the “Agencia Estatal de Investigación”. A.J. Molina and M. Moreno de las Heras are beneficiaries of Juan de la Cierva post-doctoral fellowships; and C. Cayuela, of an FPI grant, all of them funded by the Spanish Ministry of Economy and Competitiveness. Support provided by A. Löchner, X. Huguet, M. Roig-Planasdemunt, E. Sánchez-Costa, G. Bertran is also acknowledged. The constructive comments of two anonymous reviewers on an earlier version of this manuscript are thanked.

Although temporary rivers are very common in many regions of the world, there has been a general failure to understand, protect and manage this type of freshwater ecosystems. In Europe, the implementation of the Water Framework Directive has been unable to provide a solution to determine the ecological status of temporary water bodies. The first reason for this failure is the lack of attention to and knowledge of the hydrological regime of these rivers that includes diverse phases relevant to aquatic life such as flow, stagnant pools and dry stream bed. The second reason is that quality assessment tools using biological quality indicators have been developed primarily for perennial rivers and therefore are inadequate for rivers with hydrological regimes as complex as temporary rivers undergo. In order to tackle these challenges, the LIFE+ TRivers project (LIFE13 ENV/ES/000341) has addressed the following targets: - Development and implementation of operational methods for obtaining information on the temporal patterns of the diverse states and phases that characterize the hydrological regime of temporary rivers. - Classification of temporary river regimes on the basis of updated concepts beyond flow measurements, critical for the development of aquatic life. - Categorization of the diverse regime features that help to assess the degree of hydrological alteration of the natural regimes and obtain an hydrological status. - Design of calendars and protocols for monitoring the characteristics of bio indicators according to the diverse aquatic phases of the river regime. - Test and improvement of biological quality indicators for their application to temporary rivers. - Development of the TREHS software tool that includes all the former features. TREHS has been tested for hydrology in over 100 test water bodies and for all the developments in 25 pilot river sites. - Public participation and proposal of measures for improving both the hydrological and biological status of an example set of temporary water bodies.

(1) Mediterranean Ecogeomorphological and Hydrological Connectivity Research Team (http://medhycon.uib.cat), Department of Geography, University of the Balearic Islands, Carretera de Valldemossa Km 7.5 07122, Palma, Spain, (2) Institute of Agro-Environmental and Water Economy Research –INAGEA, University of the Balearic Islands, (3) Institute of Earth and Environmental Science, University of Potsdam, Karl-Liebknecht-Straße 24/25, 14476 Potsdam-Golm, Germany, (4) Institute of Environmental Assessment and Water Research (IDAEA), Spanish Research Council (CSIC), Jordi Girona 18, 08034 Barcelona, Spain Mediterranean catchments are characterized by high inter-intra annual precipitation variability and summer drought. The hydrological regime is characterized by ephemeral behaviour due to the direct rainfall-runoff relationship. Furthermore, extreme precipitations can generate an amount of rainfall higher than 200 mm in 24 hours with short response time. These events occurred normally under wet soil moisture conditions. The Mediterranean catchment morphology is a favourable factor for flash floods: short catchments with a high gradient slope. Others factor that condition the hydrological regime are the presence of limestone lithology and the impact of human activities on fluvial systems as geomorphological changes in channels and flood plains. The aim of this study is analyse the hydrological response of five hydrological years (2012-17) in an agricultural headwater catchment (i.e. < 4 km2) at different time scales. Rainfall-runoff relationship was carried out at annual and seasonal scale through the flow duration computation, the variability index, 30/70 ratio, quick flow response ratio and base flow index. The rainfall-runoff relationship at event scale was carried out through a Pearson correlation matrix using different variables extracted from the hyetograph and hydrograph. These variables were placed into two groups: a) antecedent conditions and b) event conditions. The correlation results determined the involved factors in the hydrological response. At annual scale total flow was present for 42.8% of the time and quick flow was 1.4%. The Variability index value (0.64) was higher than catchments with high dynamics storage (Vi < 0.5). At season scale, winter with 90.6%, showed the highest discharge presence. This highest discharge percentage duration generated a sustained water storage (Vi: 0.55) and increased the soil moisture from autumn getting favourable conditions for runoff generation. Because of that, winter had the highest quick flow duration (3.1%) and also the 30/70 denotes an increase of the flow variability. Autumn and spring had lower percentage of discharge duration than winter, 53% and 41% respectively. Autumn is the season after the dry season when starts again the wet period getting favourable conditions for runoff generation. Spring denotes the importance of the accumulated precipitation contribution of the wet seasons, also indicated for the highest seasonal BFI (0.7). Summer presented flow and quick flow the 0.93% and 0.21% of time respectively. At event scale, peak discharge, mean discharge, runoff and quick flow showed significant correlations (p

Even though throughfall is the dominant input of water to forests, many questions remain about the temporal fine-scale mechanisms controlling the redistribution of rainfall by forest canopies. Hydrologists must therefore combine different methods in novel way to achieve breakthroughs in our understanding of rainfall partitioning and its interactions with pre-event water storage on tree surfaces. Here, we apply a combination of isotopes (oxygen and hydrogen) and laser disdrometers to quantify the isotopic composition of free, splash, and release throughfall at the sub-event timescale. For individual events, isotopic differences between throughfall and open rainfall may indeed vary in magnitude and direction as a result of evaporation, exchange or selection processes. Our working hypothesis is that relating the sub-event timescale throughfall measurements with that of drop size distribution and of isotopic variations will provide an unprecedented understanding of the throughfall generation process. Such an understanding would be required to fully and accurately track the transfer of moisture from the canopy to the forest floor. This work performed in a Scots pine forest under Mediterranean conditions is based on the continuous (5min data) measurement of open rainfall and throughfall amounts (by means of tipping-buckets) and of drop size distributions (laser disdrometers) at the same two locations. In addition, rainfall and throughfall passing through the laser disdrometers and the tipping buckets are finally collected sequentially by means of automatic samplers. This presentation will show preliminary findings on the relationship between throughfall drop size and isotopic composition for several rainfall events of different magnitudes and intensities, helping to reveal how water moves through flowpaths and storage reservoirs in the canopy.