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A novel methodology for the optimal placement of sensors in watercourses is presented. The methodology aimed at finding the optimal locations for the placement of sensors to maximize the amount of information to monitor flow and velocity in watercourses. The methodology is based on the maximization of the Gram determinant of the sensor responses at each possible location or a combination of locations. Two illustrative examples are presented wherein locations for one- and two-sensor cases for the velocity and flow monitoring of the Venero Claro River Basin, Spain, are selected. The kinematic wave method was used to evaluate the sensor response at every possible location. The results confirm the suitability of this methodology for finding the optimal locations for sensors to monitor flow or velocity in watercourses. [ABSTRACT FROM AUTHOR]

Abstract Ensuring water is available for human use usually requires dams and reservoirs that severely affect river ecosystems. Hydrological alteration by river damming represents one of the most prominent human impacts on freshwater ecosystems. This paper presents a methodological approach to assessing the natural patterns of flow variability and hydrological alterations in Mediterranean rivers. The methodology first defines the admissible range of flow variability under a natural flow regime. Then, the methodology measures the environmental impact of flow regulation according to the inferred hydrological alteration and classifies rivers into homogeneous groups according to the magnitude, frequency, duration and seasonality of the impacts. This paper applies the proposed methodology to thirty-three river segments below large reservoirs located in the three largest Spanish watersheds (Duero, Ebro and Tajo). For each segment, this study evaluates the general impoundment characteristics and geographical contexts and calculates the flow impacts and the divergence between the circulating flows and the reference area of admissible flow variability on a daily basis for the period 2000–2010. This assessment of dam regulation impacts provides a reference to plan measures for mitigating these impacts. The advantages of this flow regulation impact analysis over other analyses are discussed in terms of the implementation of environmental water costs as suggested by the European Water Framework Directive. This approach expands the current understanding of water environmental costs and represents a practical management tool for decreasing the environmental impacts of flow regulation and for increasing water-use efficiency. Highlights • Natural range of flow variability discriminates distinct hydrologic regime patterns. • Flow regulation impacts are not significantly influenced by climate or geomorphology. • Flow regulation impacts strongly depend on dam operation and water use. • Flow reductions in winter and increases in summer are common in Mediterranean rivers. • Deviations from natural flow variability should inform damming environmental costs. [ABSTRACT FROM AUTHOR]

Abstract Dissolved solids (DS) and suspended sediment (SS) loads are considered relevant environmental problems. They are related to a wide range of on-site and off-site impacts, such as soil erosion or salinization of water bodies. In this study, the dynamics of DS and SS concentrations and loads were assessed in five small watersheds covering representative agricultural land uses in Navarre (Spain). To this end, discharge, DS and SS concentration data were collected during ten hydrological years at each watershed outlet, and loads were computed from discharge and concentration values. DS concentration followed a seasonal pattern imposed by the availability of water, with higher concentrations recorded in low-flow periods and lower concentration in the high-flow period. SS concentration was extremely variable, with a range of 2–4 orders of magnitude in concentration for any specific discharge. Temporal variations (both intra- and inter-annual) in DS loads were explained by differences in runoff, whereas those of SS were not, being the SS loads associated mainly with specific high flow events. These temporal patterns were observed for both agricultural (this study) and non-agricultural (literature) watersheds. From the data in the Navarrese watersheds and those available in the literature, we inferred that agricultural land use, in general, tends to increase the concentration of both DS and SS. Regarding DS and SS yields, the effects of agricultural land use on DS yields are controlled by the changes in runoff rather than the (small) changes in DS concentration. In this sense, land uses changes expected to increase runoff (i.e., a shift from forested to arable or from rainfed to irrigated agriculture) would increase DS yields. On the other hand, agricultural land use tends to increase SS yields, although the effect is highly variable depending on site-specific factors, both natural (e.g., watershed shape) and anthropogenic (e.g., degree of soil conservation practices). In the Navarrese watersheds, DS yields ranged from 1.1 to 2.2 Mg ha−1 year−1 whereas SS yields ranged from 0.3 to 4.3 Mg ha−1 year−1. DS yields seem to dominate under non-agricultural conditions and in most agricultural land uses at the small watershed scale. On the other hand, SS yields dominate in watersheds with increased soil erosion as a consequence of arable land use over erosion-prone watersheds. Highlights • Dissolved solids concentration follows a seasonal pattern. • Suspended sediment concentration was extremely variable. • Dissolved loads behave conservatively with water. • The dissolved load dominated the exportation in most of the cases. • Agricultural land use increases suspended sediment concentration and loads. [ABSTRACT FROM AUTHOR]

Assessing water resources in high mountain semi-arid zones is essential to be able to manage and plan the use of these resources downstream where they are used. However, it is not easy to manage an unknown resource, a situation that is common in the vast majority of high mountain hydrological basins. In the present work, the discharge flow in an ungauged basin is estimated using the hydrological parameters of an HBV (Hydrologiska Byråns Vattenbalansavdelning) model calibrated in a “neighboring gauged basin”. The results of the hydrological simulation obtained in terms of average annual discharge are validated using the VI-ETo model. This model relates a simple hydrological balance to the discharge of the basin with the evaporation of the vegetal cover of the soil, and this to the SAVI index, which is obtained remotely by means of satellite images. The results of the modeling for both basins underscore the role of the underground discharge in the total discharge of the hydrological system. This is the result of the deglaciation process suffered by the high mountain areas of the Mediterranean arc. This process increases the infiltration capacity of the terrain, the recharge and therefore the discharge of the aquifers that make up the glacial and periglacial sediments that remain exposed on the surface as witnesses of what was the last glaciation. [ABSTRACT FROM AUTHOR]

• We estimate the information transaction costs emerging in a water market between irrigators. • We couple a hydrologic model, a mathematical programming model and an ABM. • Results show that transaction costs can reduce the economic surplus up to 45%. The economic literature has extensively researched water markets, finding that this instrument can deliver superior resource allocations under growing scarcity. However, these assessments typically ignore the information, bargaining, and enforcement costs that occur in trades, known as transaction costs, which can be particularly relevant in emerging markets such as those for water. This paper presents a multi-agent cellular automata model that couples a positive multi-attribute utility programming (PMAUP) model with an agent-based model (ABM) to elicit the information transaction costs of water trading under alternative market and climate scenarios. A first experiment evaluates an ideal water market with no transaction costs, which is then compared to alternative decentralized spot market setups representing different degrees of information availability that are modeled using the coupled PMAUP-ABM. The difference between the economic surplus under the ideal market and that achieved under alternative market setups with information constraints is used as a proxy value of information transaction costs. Methods are illustrated with an application to the Douro River Basin in central Spain. Results show that information transaction costs can reduce the economic surplus between 0.6% and 45% depending on the scenario. [ABSTRACT FROM AUTHOR]

Summary Flash floods represent one of the most common natural hazards in mountain catchments, and are frequent in Mediterranean environments. As a result of the widespread lack of reliable data on past events, the understanding of their spatio-temporal occurrence and their climatic triggers remains rather limited. Here, we present a dendrogeomorphic reconstruction of past flash flood activity in the Arroyo de los Puentes stream (Sierra de Guadarrama, Spanish Central System). We analyze a total of 287 increment cores from 178 disturbed Scots pine trees ( Pinus sylvestris L.) which yielded indications on 212 growth disturbances related to past flash flood impact. In combination with local archives, meteorological data, annual forest management records and highly-resolved terrestrial data (i.e., LiDAR data and aerial imagery), the dendrogeomorphic time series allowed dating 25 flash floods over the last three centuries, with a major event leaving an intense geomorphic footprint throughout the catchment in 1936. The analysis of meteorological records suggests that the rainfall thresholds of flash floods vary with the seasonality of events. Dated flash floods in the 20th century were primarily related with synoptic troughs owing to the arrival of air masses from north and west on the Iberian Peninsula during negative indices of the North Atlantic Oscillation. The results of this study contribute considerably to a better understanding of hazards related with hydrogeomorphic processes in central Spain in general and in the Sierra de Guadarrama National Park in particular. [ABSTRACT FROM AUTHOR]

Despite major recent advances in socio-hydrology and hydroeconomics research, interdisciplinary methods and models for water policy assessment remain largely concealed to the academic arena. Most river basin authorities still base decision-making on inputs from hydrologic Decision Support Systems (DSS), and have limited information on the economic costs that water policies may impose on the economy. This paper presents a time-variant hierarchical framework that connects a hydrologic module and an economic module by means of two-way feedback protocols. The hydrologic module is designed to fit the AQUATOOL DSS, the hydrologic model used by Spanish river basin authorities to inform decision-making at a basin scale; while the economic module is populated with a Positive Multi-Attribute Mathematical Programming (PMAMP) model that represents the behavior and adaptive responses of irrigators. The proposed hierarchical framework is used to assess the economic repercussions of strengthening irrigation quotas so to achieve minimum environmental flows in the Douro River Basin (Spain) under climate change. Results show that reductions in agricultural water allocations to meet environmental flow requirements create nonlinear incremental profit and employment losses in irrigated agriculture that are on average low to moderate (between −4% and −12.9 % for profit, and between −4.6 % and −12 % for employment, depending on the scenario). During extreme droughts, the abrupt reductions in water availability and agricultural allocations can test farming systems past the breaking point and lead to catastrophic profit and employment losses (>80 %). • Water authorities have limited information on the economic costs of environmental flows. • We couple a microeconomic model with the widely used DSS AQUATOOL. • The coupling relies on a modular, protocol-based, time-variant hierarchical framework. • Water restrictions create nonlinear incremental profit and employment losses. • Extreme droughts test farming systems past breaking point and catastrophic losses. [ABSTRACT FROM AUTHOR]

Andalusia's lowland countryside has a network of small geographically isolated playa lakes scattered across an area of 9000 km² whose watersheds are mostly occupied by clayey rocks. The hydrological model proposed by the authors seeks to find equilibrium arnong usefulness, simplicity, and applicability to isolated playas in a semiarid context elsewhere. Based in such model, the authors have used monthly climatic data, water stage measurements, and the basin morphometry of a particular case (Los Jarales playa lake) to calibrate the soil water budget in the catchment and the water inputs from the watershed (runoff plus groundwater flow) at different scales, from monthly to daily. After the hydrologic model was calibrated, the authors implemented simulations with the goal of reproducing the past hydrological dynamics and forecasting water regime changes that would be caused by a modification of the wetland morphometry. [ABSTRACT FROM AUTHOR]

Summary: In this study the water draining from a mixed land use catchment of 16km2 in NW Spain was monitored over a 5-year period (2004/2005–2008/2009) to determine the temporal variability in phosphorus (P) transport, to examine the P fluxes and controlling factors, and to analyse the relationships between discharge and P (PP: particulate phosphorus and DP: dissolved phosphorus) at event scale. A total of 132 runoff events was analysed, providing an extensive dataset on P values under different hydrological conditions. Mean annual P export from the catchment amounted to 184kg equivalent to 11.5kgkm−2, a value relatively lower than those obtained in other mixed land use catchment. The PP accounted for 74% of the total phosphorus (TP). The intra- and inter-annual variability in P transport was high due to the fact that most of P was discharged during a short-time period: 35% of PP load and 19% of DP load occurred in only 2% of the time. Runoff events contributed to 68% of P exported during the period of study. A high variability in P transport during different runoff events was observed. Phosphorus export increased with the magnitude of runoff events and rainfall amount, suggesting that these could be the key factors controlling P yield. Erosion was also an important driving force behind P export in the catchment. The relationships between PP and DP and discharge resulted in different hysteresis patterns. The relationship PP-discharge was mainly characterised by clockwise behaviour, linked to sediment in the surface runoff, while DP-discharge was predominately anticlockwise due to transport in subsurface flow, showing different pathways of transport between PP and DP. [Copyright &y& Elsevier]

Summary: In this study we analyzed the response of monthly runoff to precedent climatic conditions at temporal scales of 1–48months in 88 catchments of the Ebro basin (northeast Spain). The standardized precipitation evapotranspiration index (SPEI) was used to summarize the climatic conditions at different time scales, and was correlated with the standardized streamflow index (SSI) calculated at the mouth of each catchment. The Ebro basin encompasses a gradient from Atlantic to Mediterranean climates, and has remarkable complexity in topography, geology and land cover. The basin is highly regulated by dams, which were built to produce hydropower and supply water for agriculture. These characteristics explain why sub-basins of the Ebro River basin respond in differing ways to precedent climatic conditions. Three main sub-basin groups were distinguished on the basis of the correlation of their streamflow responses to different time scales of the SPEI: (1) sub-basins correlated with short SPEI time scales (2–4months), which generally corresponded to unregulated headwater areas; (2) sub-basins correlated with long SPEI time scales (10–20months), where groundwater reserves play a major hydrological role; and (3) sub-basins correlated with medium SPEI time scales (6–10months). The latter occur in the lower sectors of the Ebro basin and its tributaries, which receive river flows from the other two sub-basins, and where dam regulation has a significant influence on the hydrological characteristics. In addition to the three main sub-basin groups, other streamflow responses associated with seasonal factors were identified, particularly those related to snowpack and the various management strategies applied to reservoirs. [ABSTRACT FROM AUTHOR]

Summary: This research and practical application is concerned with the development of a physically-based numerical model that incorporates new approaches for a finite element solution to the steady/transient problems of the joint surface/groundwater flows of a particular region with the help of a Geographic Information Systems to store, represent, manage and take decisions on all the simulated conditions. The proposed surface–subsurface model considers surface and groundwater interactions to be depth-averaged through a novel interpretation of a linear river flood routing method. Infiltration rates and overland flows generation processes are assessed by a sub-model which accounts for this kind of surface–groundwater interactions. Surface–groundwater interactions consider also novel evaporation and evapotranspiration processes as a diffuse discharge from surface water, non-saturated subsoil and groundwater table. The practical application regards the present flooding of the Meirama open pit, a quite deep coal mining excavation, with freshwater coming from the upper Meirama sub-basin, in the context of the water resources fate and use at the Barcés river catchment (∼87.9km2), Coruña, Spain. The developed model MELEF was applied to the complex geology of a pull-apart type sedimentary tertiary valley and the whole of the water resources of the Barcés River drainage basin, down to its outlet at the Cecebre Reservoir. Firstly, the model was adapted and calibrated during a simulation period of three and a half years (2006/2009) with the aid of the historically registered hydrological parameters and data. Secondly, the results predict the most likely forthcoming evolution of the present flooding of the Meirama open pit to reach therein a total depth level of almost 200m, as regards the projected evolution of the water resources, climatology and usages. [Copyright &y& Elsevier]

Abstract: To evaluate the vulnerability of agriculture under Mediterranean conditions, the real water needs of agriculture in the Fluvià watershed (Catalonia, NE Spain) were estimated for the XXIst century using a combination of downscaled climate projections (ECHAM5 plus MM5) in two IPCC scenarios (B1 and A2), watershed hydrological model (SWAT) and FAO procedure to calculate crop potential evapotranspiration. In comparison with baseline conditions (1984–2008), climate projections predicted a 12% (B1) to 28% (A2) reduction in precipitation, and a 2.2°C (B1) to 3.6°C (A2) increment of mean annual temperature at the end of the XXI Century (2076–2100). The changes of the environmental conditions would affect the real water availability in different crops: water required for irrigation would increase significantly along the century, ranging from 40 to 250% depending on the crop, because of a direct decrease in the amount of water available along the growing season and because of the effects of the projected climatic conditions on potential evapotranspiration (ET0) and on the phenology of these crops. Results are showing the high sensitivity of agriculture, despite its expanding technology, to changes in climate, and even more to site, plot, orchard or terroir conditions. [Copyright &y& Elsevier]

Summary: This study characterises the abatement effect of large dams with fixed-crest spillways under extreme design flood conditions. In contrast to previous studies using specific hydrographs for flow into the reservoir and simplifications to obtain analytical solutions, an automated tool was designed for calculations based on a Monte Carlo simulation environment, which integrates models that represent the different physical processes in watersheds with areas of 150–2000km2. The tool was applied to 21 sites that were uniformly distributed throughout continental Spain, with 105 fixed-crest dam configurations. This tool allowed a set of hydrographs to be obtained as an approximation for the hydrological forcing of a dam and the characterisation of the response of the dam to this forcing. For all cases studied, we obtained a strong linear correlation between the peak flow entering the reservoir and the peak flow discharged by the dam, and a simple general procedure was proposed to characterise the peak-flow attenuation behaviour of the reservoir. Additionally, two dimensionless coefficients were defined to relate the variables governing both the generation of the flood and its abatement in the reservoir. Using these coefficients, a model was defined to allow for the estimation of the flood abatement effect of a reservoir based on the available information. This model should be useful in the hydrological design of spillways and the evaluation of the hydrological safety of dams. Finally, the proposed procedure and model were evaluated and representative applications were presented. [Copyright &y& Elsevier]

Abstract: It is recognised that the hydrological and erosion processes in watersheds are very much conditioned by the (inter)action of a number of variables. This paper covers a 15-year period of studying those factors that have a major influence on the sediment yield and transport during individual hydrological events in a small Mediterranean agricultural watershed. Multivariate statistical techniques such as cluster analysis and principal component analysis were applied for the interpretation of datasets. In addition, the relationships between suspended sediment concentration and discharge (hysteretic loops) were also analysed. The hydrological response of the studied watershed is mainly controlled by the antecedent condition of the flow. Most of the runoff and sediment are generated during the wet season when vegetation cover is scant and saturation overland flow occurs promptly as a response to almost any rainfall events. In contrast, during the dry seasons even if high-intensity rainfalls normally occur, very scant runoffs are, however recorded, at the exit of the watershed. Most of the eroded sediment seems to come from riparian areas. The discharge registered at the watershed outlet up to 1h prior to the flood is a very good surrogate for antecedent soil moisture. [Copyright &y& Elsevier]

Abstract: Tree-ring analysis has been demonstrated to be a useful tool for palaeohydrology. Selecting suitable study areas is the first step in palaeoflood research using tree-ring techniques. Objective methods are needed to facilitate exploration and subsequent location of basins where sediment-laden flash floods are likely and that also have tree species suitable for dendrogeomorphological research in a palaeohydrological context. This paper presents a novel methodology for selecting preliminary suitable watersheds for dendrogeomorphological palaeoflood research in central Spain. Geographical information systems (GIS) provide decision-makers with a powerful set of tools for the manipulation and analysis of spatial information. Using GIS tools and basic thematic maps, we defined three different indexes concerning the occurrence of dendrogeomorphological evidence. A Consensus Decision Making procedure (CDM) was carried out in order to weight each factor individually prior to combining the factors. As a result, we obtained information about the most appropriate watersheds for palaeoflood research using tree-ring analysis. A total of 189 watersheds appeared to be highly interesting for tree-ring studies. Of these only 17 have flow gauges, so data concerning frequency and magnitude of floods in basins without gauges could potentially be provided by dendrogeomorphological studies. In order locate such sites and to carry out such studies more efficiently, a more objective methodology for selecting watersheds for tree-ring studies is presented. [Copyright &y& Elsevier]

The hydrological response of a small agroforestry catchment in northwest Spain (Corbeira catchment, 16 km2) is analysed, with particular focus on rainfall events. Fifty-four rainfall–runoff events, from December 2004 to September 2007, were used to analyse the principal hydrological patterns and show which factors best explain the hydrological response. The nonlinearity between rainfall and runoff showed that the variability in the hydrological response of the catchment was linked to the seasonal dynamics of the rainfall and, to a lesser extent, to evapotranspiration. The runoff coefficient, estimated as the ratio between direct runoff and rainfall volume, on an event basis, was analysed as a function of rainfall characteristics (amount and intensity) and the initial catchment state conditions prior to an event, such as pre-event baseflow and antecedent rainfall index. The results revealed that the hydrological response depends both on the soil humidity conditions at the start of the event and on rainfall amount, whereas rainfall intensity presented only a significant correlation with discharge increment. The antecedent conditions seem to be a key point in runoff production, and they explain much of the response. The hydrographs are characterized by a steep rising limb, a relatively narrow peak discharge and slow recession limb. These data and the observations suggest that the subsurface flow is the dominant runoff process. Editor Z.W. Kundzewicz; Associate editor T. Wagener Citation Rodríguez-Blanco, M.L., Taboada-Castro, M.M. and Taboada-Castro, M.T., 2012. Rainfall–runoff response and event-based runoff coefficients in a humid area (northwest Spain). Hydrological Sciences Journal, 57 (3), 445–459. [ABSTRACT FROM AUTHOR]

Stratigraphic and sedimentological analyses of the Quaternary tufa and associated deposits in the Piedra and Mesa river valleys allowed a number of stages of their sedimentary evolution to be characterized, and a depositional sedimentary model for this north-central sector of the Iberian Range (Spain) to be established. The proposed sedimentary facies model may explain tufa arrangements in other medium to high gradient, stepped, fluvial tufa systems with narrow transverse profiles occurring in temperate, semi-arid areas, in both recent and past scenarios. There are several tufa deposits within the Piedra and Mesa river valleys that, over a maximum thickness of about 90 m, record one or more stages of tufa deposition produced following the fluvial incision of the bedrock or previous tufa deposits. Each depositional stage begins with coarse detrital sedimentation. Six fundamental, vertical sequences of tufa facies with small amounts of detrital material reveal the sedimentary processes that occurred in different fluvial environments: channel areas with: (i) free-flowing water; (ii) barrages and/or cascades; and (iii) dammed water and palustrine floodplains. The proposed sedimentary model involves narrow, stepped, fluvial valleys in which tufa cascades were common. Alternating intervals of bryophyte and stromatolite facies commonly formed at some cascades. Many of these represented barrage-cascade structures that consisted of phytoclast rudstones, thick phytoherms of mosses and associated stromatolites, and curtain-shaped phytoherms of stems. Upstream of these structures, dammed areas with bioclastic sands and silts developed and palustrine vegetation grew. The channel stretches between barrages and/or cascades were loci for extensive stromatolite growth in fast flowing water. The palustrine floodplain was home to pools and drainage channels. The model also explains the growth of some barrages in the River Piedra that surpassed the height of the divide, with the diffluence of the main channel into a secondary course forming other tufa deposits in the area. The distribution and abundance of certain types of tufa facies in fluvial basins may be an indicator of differences in their gradients. The facies studied in this work suggest that the gradient of the ancient River Piedra was steeper than that of the ancient River Mesa. Assuming similar scenarios for climate and hydrology, the depositional settings mentioned above and their dimensions would have been determined mainly by the gradient and width of the associated river valleys. This sedimentary model may also be useful for inferring variations in other river basin slopes, as well as accounting for the presence of tufas in areas that normally have no permanent water input. [ABSTRACT FROM AUTHOR]

Summary: A methodology to analyze impact, vulnerability and adaptation to climate change in conjunctive-use systems at basin scale is presented. Based on the value obtained for various indices under possible future scenarios (indices obtained from the results of a system management model), a systematic procedure is presented to identify problems and solutions to adapt to climate change effects. The future hydrological scenarios to be analyzed can be approached by starting from the historical series available for the system and taking into account the changes expected in the key statistics of the series. A method to predict the expected changes in the key statistics using the results of previous climate change studies in the area has been developed. A “downscaling” procedure is proposed to translate the climatic variations into results on a basin scale. The methodology has been applied to the case study of the Serpis River Basin (Eastern Spain). [ABSTRACT FROM AUTHOR]

Abstract: The hydrological and geomorphic effects of land use/land cover changes, particularly those associated with vegetation regrowth after farmland abandonment were investigated in the Central Spanish Pyrenees. The main focus was to assess the interactions among slope, catchment, basin, and fluvial channel processes over a range of spatial scales. In recent centuries most Mediterranean mountain areas have been subjected to significant human pressure through deforestation, cultivation of steep slopes, fires, and overgrazing. Depopulation commencing at the beginning of the 20th century, and particularly since the 1960s, has resulted in farmland abandonment and a reduction in livestock numbers, and this has led to an expansion of shrubs and forests. Studies in the Central Spanish Pyrenees, based on experimental plots and catchments, in large basins and fluvial channels, have confirmed that these land use changes have had hydrological and geomorphic consequences regardless of the spatial scale considered, and that processes occurring at any particular scale can be explained by such processes acting on other scales. Studies using experimental plots have demonstrated that during the period of greatest human pressure (mainly the 18th and 19th centuries), cultivation of steep slopes caused high runoff rates and extreme soil loss. Large parts of the small catchments behaved as runoff and sediment source areas, whereas the fluvial channels of large basins showed signs of high torrentiality (braided morphology, bare sedimentary bars, instability, and prevalence of bedload transport). Depopulation has concentrated most human pressure on the valley bottoms and specific locations such as resorts, whereas the remainder of the area has been affected by an almost generalized abandonment. Subsequent plant recolonization has resulted in a reduction of overland flow and declining soil erosion. At a catchment scale this has caused a reduction in sediment sources, and channel incision in the secondary streams. At the regional scale, the most important consequences include a reduction in the frequency of floods, reduced sediment yields, increasing stabilization of fluvial channels (colonization of sedimentary bars by riparian vegetation and a reduction in the braiding index), and stabilization of alluvial fans. These results demonstrate the complexity and multiscalar nature of the interactions among land use and runoff generation, soil erosion, sediment transport, and fluvial channel dynamics, and highlight the need to adopt a multiscale approach in other mountain areas of the world. [Copyright &y& Elsevier]

Summary: The Meca River is highly contaminated by acid mine drainage coming from the Tharsis mining district, belonging to the Iberian Pyrite Belt. This river is regulated by the Sancho reservoir (58hm3), with a pH close to 4.2. In this work, the load transported by the Meca River to the Sancho reservoir has been assessed. Due to the lack of streamflow data, the hydrological behaviour of the Meca River basin has been simulated using the SWAT model. The model has been calibrated against registered daily inflows of the Sancho reservoir (1982–2000), excluding the hydrological years 2000/2001 and 2001/2002 that were kept for the validation. The results were satisfactory; the evaluation coefficients for monthly calibration were: r =0.85 (Pearson’s correlation coefficient), NSE=0.83 (Nash–Sutcliffe coefficient) and DV=1.08 (runoff volume deviation). The main uncertainty was the calibration during low water because of the poor accuracy in the measurement of the inputs to the reservoir in these conditions. Discharge and dissolved concentration relationships for different elements were obtained from hydrochemical samplings, which allowed us to estimate the element pollutant load transported to the reservoir: 418ton/year of Al, 8024ton/year of SO4, 121ton/year of Zn, etc. Based on these loads, concentrations in the reservoir were calculated for some elements. Apart from Mn and Sr, good adjustment between calculated and measured values was observed (±20% for Ca, Co, Li, Mg, Na, Ni, Zn and SO4). Capsule: Hydrological model combined with water quality data show how pollution by AMD can generate huge loads of contaminants acidifying streams and reservoirs. [Copyright &y& Elsevier]

Abstract: Runoff and erosion processes are often non-linear and scale dependent, which complicate runoff and erosion modelling at the catchment scale. One of the reasons for scale dependency is the influence of sinks, i.e. areas of infiltration and sedimentation, which lower hydrological connectivity and decrease the area-specific runoff and sediment yield. The objective of our study was to model runoff and erosion for a semi-arid catchment using a multi-scale approach based on hydrological connectivity. We simulated runoff and sediment dynamics at the catchment scale with the LAPSUS model and included plot and hillslope scale features that influenced hydrological connectivity. The semi-arid Carcavo catchment in Southeast Spain was selected as the study area, where vegetation patches and agricultural terraces are the relevant sinks at the plot and hillslope scales, respectively. We elaborated the infiltration module to integrate these runoff sinks, by adapting the parameters runoff threshold and runoff coefficient, which were derived from a rainfall simulation database. The results showed that the spatial distribution of vegetation patches and agricultural terraces largely determined hydrological connectivity at the catchment scale. Runoff and sediment yield for the scenario without agricultural terraces were, respectively, a factor four and nine higher compared to the current situation. Distributed hydrological and erosion models should therefore take account of relevant sinks at finer scales in order to correctly simulate runoff and erosion-sedimentation patterns. [Copyright &y& Elsevier]

Abstract: The ichnological study of fluvial fan and lacustrine Oligocene deposits in the NE Ebro Basin has allowed the recognition of three ichnoassemblages having a strong correlation with depositional facies associations. Lacustrine deposits lack bioturbation due to the hydrologically closed character of the lake that caused hypersalinity and made it inhospitable for benthic life. Terminal lobe deposits of the fluvial fan, which were sedimented in low wetland areas around the lake, bear a moderately diverse ichnoassemblage dominated by horizontal Taenidium barretti, Cochlichnus anguineus and bird footprints (Gruipeda isp.). This assemblage can be assigned to the ''shorebird ichnofacies'', a subset of the Scoyenia ichnofacies that characterizes the subaerial part of low-energy shore areas. Crevasse splay deposits in medial fluvial fan areas present a different assemblage also belonging to the Scoyenia ichnofacies. It includes most of the trace fossils found in the terminal lobes, except for the bird tracks, plus very abundant vertical burrows (Taenidium barretti and unnamed ornamented burrows). The presence of deep-tier traces of terrestrial invertebrates is consistent with the more proximal fan setting, having greater relief and consequently a lower mean groundwater position than lowland areas. Fluvial channels only bear irregularly clustered tunnel structures of unknown affinity formed after abandonment of the channel. Thus, trace fossil assemblages are mostly controlled by the position and fluctuations of water tables, which are the cause for their composite nature. [Copyright &y& Elsevier]

Summary: This paper describes a study developed to estimate available surface water resources in twelve basins in the north of Spain by means of numerical tools. These basins are characterized by their small surface area, short length, steep slope, and scarce hydrological gauging. The available information has conditioned the use of a lumped continuous simulation hydrological model. The HEC-HMS program with continuous soil moisture accounting (SMA) model was chosen. The model development is described in detail, focusing on the methodology used to fill the incomplete daily rainfall series and to establish the daily uniform precipitation over the sub-basins taking advantage of the results provided by a previous study with different time scale. Several techniques were used to calibrate and validate the hydrologic model, since few stream gauges were available. Comparison between observed flow data and results provided by simulation was in good agreement. The model application allowed assessment of the daily flow series at different main stream locations during a continuous time period up to thirty-three water years. These series have been used as input data for instream flows studies following the guidelines of the European Water Framework Directive. The processing of results allowed for analysis of the hydrological behaviour of the selected basins focusing in low water periods. [Copyright &y& Elsevier]

Abstract: 1800ha of El Partido stream watershed, SW Spain, have been purchased by the Spanish Ministry of Environment to enlarge Doñana National Park. Prior to incorporation, a functional restoration will be carried out. El Partido stream is building a depositional sandy delta on Doñana Marsh (now ca. 400ha) with little or no vegetation. Restoration Project envisages: [-] Building a hydraulic scheme favoring sand deposition upriver avoiding its transfer to the Marsh. [-] Restoring natural ecosystems previously existing in the area. The restoration project was divided into phases. First phase (342ha) was based on self-organization of plant communities (self-design) during succession. Existing remnants of woody vegetation covering about 7.66ha (2.2%) will be restored, adding about a three-fold surface (26.8ha, 7.8%) of new plantations. Also, 545 new vegetation patches, initially covering 20.53ha (about 6% of the area) will be planted, following composition and structure of the natural shrubbery. Each patch combines 5–10 perennial species: a core of a few trees, an inner area with some fruit–bearing scrub and the outer fringe with flower–bearing scrub. River banks will also be vegetated. Patch vegetation will attract insects and vertebrates (mostly birds), the latter eventually performing as dispersers of seeds, thus expanding the shrubbery. Finally, the restored area will provide the menaced Imperial eagle and Iberian lynx an appropriate hunting ground. [Copyright &y& Elsevier]

• Causal reasoning applied to evaluate spatio-temporal dependences in river basins. • Results from Causal reasoning are in line with classic statistical analysis. • Causal reasoning provides more information on dependences than classic methods. • Changes in spatio-temporal dependences for dry years can be assessed with causality. • Causal reasoning improves water management at seasonal scale over classic methods. This paper aims to assess fully the spatio-temporal dependence dimensions of inflow across two adjacent and parallel basins and among different time steps through Causality. This is addressed from the perspective of Causal Reasoning, supported by Bayesian modelling, under a novel framework named Bayesian Causal Modelling (BCM). This is applied, through a "concept-proof", to the Jucar River Basin (the second largest basin of Eastern Spain, characterized by long and severe drought conditions). In this "concept-proof" a double goal is evaluated; first dedicated to a lumped analysis of dependence and second a specific one over dry periods focused on time-horizon of the Jucar basin typical drought (3 years). These challenges comprise the development of two fully connected Bayesian Networks (BNs), one for each challenge populated/trained from historical-inflow records. BNs were designed at a season-scale and consequently, time was upscaled and grouped into Irrigation and Non-Irrigation periods, according to Jucar River Basin Authority operational practices. Results achieved showed that BCM framework satisfactorily captured the spatio-temporal dependencies of systems. Furthermore, BCM is able to answer to some key questions over interdependencies between adjacent and parallel subbasins. Those questions may comprise, the amount of spatial dependences among time series, the temporarily conditionality among subbasins and the spatio-temporal dependence among basins. This provides a relevant insight on the intrinsic spatio-temporal dependence structure of inflow time series in complex basins systems. This approach could be very valuable for water resources planning and management, due to its application power for predicting extreme events (e.g. droughts) as well as improving and optimizing the reservoirs operation rules. [ABSTRACT FROM AUTHOR]

• Water resources from the Pyrenees are decreasing and will continue in the future. • These reductions may threaten the long-term sustainability of downstream uses. • A multi-model and multi-scenario was used to assess water resource management process. • Application of this approach to the largest irrigated system the EU. • Results highlight the need to implement further climate adaptation measures. The Pyrenees are the main source of water for a large region in Southern Europe. In recent decades, streamflow and snow accumulation in these mountains have decreased, and climate models predict that further reductions in water will threaten the sustainability of downstream regions. This article presents a cascading multi-model and multi-scenario approach to assess how future climate change may affect the hydrology and water management of Pyrenees-dependent systems. In particular, we combined future climate projections and management scenarios and applied them to the Gállego-Cinca River System in the Ebro River Basin of Spain. We developed a hydrologic model for the headwaters of this system (the source of most of the water), and then used a management model to simulate reservoir operation and water allocation among the different agricultural demand units of this system, the largest irrigated region in Spain. We assessed future headwater streamflow for 22 climate models, and translated this climate signal into a management model by using a delta change approach. Finally, we evaluated the performance and sustainability of the system with indicators based on the frequency, duration, and magnitude of the supply deficit. The results show that use of the current planned management scenarios will threaten to the system's future sustainability, especially for irrigated agriculture. These results indicate a need to revise current water resource planning strategies in this region, and to establish long-term, robust, and sustainable measures for adaptation to climate change. [ABSTRACT FROM AUTHOR]