Much of the water and sediment fluxes in semi-arid catchments are found to be highly concentrated in localized pathways. Identifying the location of these pathways in the landscape is important for management and restoration. Measures can then be targeted so as to minimize the potential for erosion and sediment flux along these pathways. A method of repeat field mapping of flow and sediment pathways suitable for Mediterranean catchments is presented. Several small catchments in Cárcavo basin, SE Spain, differing in topographic and land use characteristics, were monitored under several events. Morphometric properties of pathways were analysed and compared with rainfall characteristics. Number and length of pathways varied with rainfall characteristics and also antecedent conditions. In low rainfall events, runoff sources and main pathways were disconnected, but in a larger event, the network of pathways became fully connected. The pathway patterns showed that man-made lines such as terrace embankments and tracks have a major influence on sediment connectivity. Microtopographic factors, soil moisture and the presence of vegetation are highly influential on pathways and the frequency of water and sediment fluxes. Runoff and erosion hotpots for the development of pathways were identified, which should be targeted for mitigation and restoration measures using vegetation. The relevance of local scale factors emphasizes the importance of repeat field observations to understand connectivity and pathways development in the landscape.

–  The spawning period of brown trout (Salmo trutta L.) was studied in the river Castril, southern Spain, by means of redd counts. This mountain stream is located near to the southern limit of the species’ natural distribution range and it shows a highly unpredictable flow regime. The spawning period extended from December to mid‐April and the maximum reproductive activity was in February. These results represent the latest reproduction date and the longest spawning period reported in the literature along the natural distribution range of the species. However, belated spawning in the Castril is congruent with the known latitudinal cline: the lower the latitude, the later the spawning period. Our results, along with a review of the literature on natural populations, also showed that the duration of reproduction is the longer, the lower the latitude. Spawning lasted twice as long in the main stem of the river, which is connected with a reservoir, than in the isolated reaches. These differences may be linked to the influence of the reservoir and to habitat fragmentation. We discuss and support the hypothesis that a long spawning period is an advantage for survival in unpredictable habitats. The belated and protracted spawning period found in river Castril has important implications in fisheries management. A strong research effort is needed in order to fill the critical lack of data on southern brown trout populations.

Monitoring forest–agriculture mosaics is crucial for understanding landscape heterogeneity and managing biodiversity. Mapping these mosaics from remotely sensed imagery remains challenging, since ecological gradients from forested to agricultural areas make characterizing vegetation more difficult. The recent synthetic aperture radar (SAR) Sentinel-1 (S-1) and optical Sentinel-2 (S-2) time series provide a great opportunity to monitor forest–agriculture mosaics due to their high spatial and temporal resolutions. However, while a few studies have used the temporal resolution of S-2 time series alone to map land cover and land use in cropland and/or forested areas, S-1 time series have not yet been investigated alone for this purpose. The combined use of S-1 & S-2 time series has been assessed for only one or a few land cover classes. In this study, we assessed the potential of S-1 data alone, S-2 data alone, and their combined use for mapping forest–agriculture mosaics over two study areas: a temperate mountainous landscape in the Cantabrian Range (Spain) and a tropical forested landscape in Paragominas (Brazil). Satellite images were classified using an incremental procedure based on an importance rank of the input features. The classifications obtained with S-2 data alone (mean kappa index = 0.59–0.83) were more accurate than those obtained with S-1 data alone (mean kappa index = 0.28–0.72). Accuracy increased when combining S-1 and 2 data (mean kappa index = 0.55–0.85). The method enables defining the number and type of features that discriminate land cover classes in an optimal manner according to the type of landscape considered. The best configuration for the Spanish and Brazilian study areas included 5 and 10 features, respectively, for S-2 data alone and 10 and 20 features, respectively, for S-1 data alone. Short-wave infrared and VV and VH polarizations were key features of S-2 and S-1 data, respectively. In addition, the method enables defining key periods that discriminate land cover classes according to the type of images used. For example, in the Cantabrian Range, winter and summer were key for S-2 time series, while spring and winter were key for S-1 time series.

Please cite this article as: Martín, P.E., Herrera, G., Sacristán, M.M., Tomás, R., Béjar-Pizarro, M., Marín, R.M., A quasi-elastic aquifer deformational behavior: Madrid aquifer case study, Journal of Hydrology (2014), doi: http:// dx.doi.org/10. 1016/j.jhydrol.2014.08.040 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

There is an urgent need to quantify anthropogenic influence on forest carbon stocks. Using satellite-based radar imagery for such purposes has been challenged by the apparent loss of signal sensitivity to changes in forest aboveground volume (AGV) above a certain ‘saturation’ point. The causes of saturation are debated and often inadequately addressed, posing a major limitation to mapping AGV with the latest radar satellites. Using ground- and lidar-measurements across La Rioja province (Spain) and Denmark, we investigate how various properties of forest structure (average stem height, size and number density; proportion of canopy and understory cover) simultaneously influence radar backscatter. It is found that increases in backscatter due to changes in some properties (e.g. increasing stem sizes) are often compensated by equal magnitude decreases caused by other properties (e.g. decreasing stem numbers and increasing heights), contributing to the apparent saturation of the AGV-backscatter trend. Thus, knowledge of the impact of management practices and disturbances on forest structure may allow the use of radar imagery for forest biomass estimates beyond commonly reported saturation points.

SUMMARY Keywords:Flow regime Reference conditions Hydrologic alteration Flow classification Prediction Fluvial restoration Natural intra-annual flow fluctuations vary between rivers, being a determining factor for aquatic insects, fish and riparian communities which are adapted to the habitat conditions and different flows throughout the seasons. Moreover, restoration of seasonal flow patterns plays an important role in achieving good ecological status of rivers, through the preservation and/or recovery of components and processes of natural river ecosystems. In this work we: (a) classify fluvial segments in the Ebro basin (North-Eastern Spain) according to the intra-annual variability of flows under natural conditions using statistical cluster analysis of monthly mean flow data; (b) characterise the resulting flow typologies according to several ecologically important hydrological variables; (c) analyse the relationships between flow regimes of fluvial segments and physical variables from their catchments; and finally (d) predict the most probable natural flow regime using logistic models based on the most determinant physical characteristics. Fifteen natural flow typologies were described in the Ebro basin, which were characterised in terms of flow fluctuation through the year as well as timing, flow ratio and duration of the maximum and minimum flows. Precipitation, biogeography and geology of catchments showed the highest correlations with flow regimes. Basin size, mean elevation and slope were also correlated. The logistic model we developed had a prediction success of 72% in the Ebro basin. The definition of the natural hydrological conditions (to which the biological communities are tailored), even when flow data are not available, is an important support in the management of river ecosystems. It is especially suitable for setting goals in aquatic ecosystem conservation or restoration projects.

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Questions: Do Mediterranean riparian guilds show distinct responses to stream water declines? If observed, which are the most sensitive and resilient guilds and their most affected attributes?Location: Tiétar river below the Rosarito dam, central-western Spain. Methods:We identified riparian guilds based on key woody species features and species distribution within this Mediterranean river corridor, and evaluated similarity of their responses to long-term flow alteration (i.e. stream water declines since dam construction in 1959). Hierarchical cluster analysis was used to group surveyed vegetation bands according to species composition. The groups were designated as riparian guilds where each vegetation group comprising a guild: (1) contains species sharing similar features (using PCA); and (2) shares a similar environment (using DCA). Changes in several guild attributes (i.e. dominance and species composition, diversity and establishment patterns) during the regulated period were compared statistically. We used pre-and post-dam established vegetation bands identified based on old (1956) and modern (2006) aerial photographs and field measurements of woody species diameter. Results:Responses to flow alterations varied between guilds according to ecological requirements of their species. The ability to survive water stress (i.e. 'Xeric' guilds) and drag forces caused by floods ('Torrential' guilds) allowed certain pioneer shrub-dominated guilds (e.g. Flueggea tinctoria and Salix salviifolia) to spread on newly emerged surfaces downward to the main channel after flow alterations, although new shrubland had less species diversity than pre-dam shrubland. In contrast, new hydromorphological conditions following damming limited recruitment of native late-successional tree guilds sensitive to floods (to drag forces, inundation and anoxia; i.e. 'Slow-water' and 'Flood-sensitive', respectively) and those with greater water requirements (i.e. 'Hydric') (e.g. Alnus glutinosa and Celtis australis), although species diversity increased in this mature forest through co-existence of remaining riparian species and new arrival of upland species.Conclusions: Changes in several riparian attributes after flow alterations differed between guilds. Stream water declines after damming caused shifts in species-poor pioneer shrubland downwards to the watered channel, resulting in severe declines of mature native forest. Understanding vegetation guild responses provides information about general trends in plant populations and assemblage structures expected to occur during river development and flow regulation, increasing our capacity to detect and synthesize complex flow alteration-riparian ecosystem response relationships, and anticipate irreversible impacts.