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Non‐perennial streams have a global prevalence, but quantitative knowledge of the temporal dynamics of their flowing length—namely the extent of the wet portion of the stream network—remains limited, as the monitoring of the spatiotemporal configuration of wet channels is challenging in most settings. This work combines the high spatial resolution of visual surveys and the high temporal resolution of camera‐based approaches to reconstruct the space‐time stream network dynamics in a 3.7 km2 Mediterranean catchment of central Italy. Information on the hydrological status of the stream network derived from 40 field surveys and sub‐hourly images collected with 21 stage‐cameras are combined exploiting the hierarchical principle. The latter postulates the existence of a Bayesian chain, defined from the local persistence of the nodes that dictates their wetting/drying order during expansion/retraction cycles of the flowing stream network. Our results highlight the complexity of network dynamics in the study area: while the number of wet nodes decreases during the dry season and increases during the wet season, the local persistency exhibits a highly heterogeneous non‐monotonic spatial pattern, originating a dynamically disconnected network. Despite this heterogeneity, the hierarchical model well approximates the temporal evolution of the state of the network nodes, with an accuracy that exceeds 99%. Crucially, the model allows the reconstruction of the wet portion even in cases in which part of the network was not observed. This work provides a novel conceptual approach for the reconstruction of the wet portion of the network in poorly accessible sites. Key Points: Field data on the hydrological status of the drainage network are collected via heterogeneous spatiotemporal resolution techniquesData are combined to reconstruct the long‐term active drainage network dynamics exploiting the hierarchical principleThe model reproduces the complexity of the non‐monotonic pattern of the wet portion of the network in the study site [ABSTRACT FROM AUTHOR]

We present here, and make freely available, two long‐term datasets on the hydrology and hydrochemistry of two small catchments totally or partially covered by holm oak (Quercus ilex) forests. Data have been collected over four decades of research on the ecology of Mediterranean evergreen forests. The datasets contain data on water fluxes in precipitation and runoff, and on the ion concentrations and fluxes in precipitation, throughfall and streamwater. Among other applications, these data have been used to obtain catchment budgets of water and elements, to document decadal changes in atmospheric deposition and streamwater chemistry, to assess the role of Saharo‐Sahelian dust on forest nutrient cycling, and to model habitat suitability for an endangered amphibian under future climates. To encourage their further use by the scientific community, in this paper we summarize the data context and methods, and give a nutshell of obtained results. We provide the links to these datasets on the Zenodo platform. [ABSTRACT FROM AUTHOR]

Human‐induced afforestation has been one of the main policies for environmental management of farmland abandonment in Mediterranean areas. Over the last decades, several studies have reviewed the impact of afforestation activities on geomorphological and hydrological responses and soil properties, although few studies have evaluated the effects on water table dynamics. In parallel to human‐induced afforestation activities, natural revegetation occurred in abandoned fields and in fields where the intensity of human activity declined, driving the expansion of shrubs. This research addresses the spatial and temporal variability of water table dynamics in a small afforested sub‐catchment located in the Central Spanish Pyrenees. Differences between afforestation (Pinus nigra and Pinus sylvestris) and natural plant colonization (shrubs, mainly Genista scorpius, Buxus sempervirens, and Juniperus communis) and early abandoned meadows (G. scorpius), are analysed in terms of runoff generation and seasonal water table depth dynamics. Precipitation, runoff and water table datasets recorded for the 2014–2019 period are used. Results show a high temporal and spatial variability with large fluctuations in discharge and water table. Groundwater dynamics varied markedly over the year, identifying a wet and dry period with different responses suggesting different runoff generation processes (Hortonian flow during dry and wet periods, and saturation excess runoff during wet conditions). Furthermore, important differences are noted among the various land cover types: (i) in the natural revegetation area (shrubland and meadows) a marked seasonal cycle was observed with short saturation periods during winter and spring; and (ii) in the afforestation areas, the water table dynamics showed a seasonal cycle with a high variability, with fast responses and rapid oscillations. Likewise, the relationship between the depth of water table and hydrological variables was not straightforward, suggesting complex hydrological behaviour. [ABSTRACT FROM AUTHOR]

In the semi-arid Mediterranean environment, the rainfall-runoff relationships are complex because of the markedly irregular patterns in rainfall, the seasonal mismatch between evaporation and rainfall, and the spatial heterogeneity in landscape properties. Watersheds often display considerable non-linear threshold behavior, which still make runoff generation an open research question. Our objectives in this context were: to identify the primary processes of runoff generation in a small natural catchment; to test whether a physically based model, which takes into consideration only the primary processes, is able to predict spatially distributed water-table and stream discharge dynamics; and to use the hydrological model to increase our understanding of runoff generation mechanisms. The observed seasonal dynamics of soil moisture, water-table depth, and stream discharge indicated that Hortonian overland-flow was negligible and the main mechanism of runoff generation was saturated subsurface-flow. This gives rise to base-flow, controls the formation of the saturated areas, and contributes to storm-flow together with saturation overland-flow. The distributed model, with a 1D scheme for the kinematic surface-flow, a 2D sub-horizontal scheme for the saturated subsurface-flow, and ignoring the unsaturated flow, performed efficiently in years when runoff volume was high and medium, although there was a smoothing effect on the observed water-table. In dry years, small errors greatly reduced the efficiency of the model. The hydrological model has allowed to relate the runoff generation mechanisms with the land-use. The forested hillslopes, where the calibrated soil conductivity was high, were never saturated, except at the foot of the slopes, where exfiltration of saturated subsurface-flow contributed to storm-flow. Saturation overland-flow was only found near the streams, except when there were storm-flow peaks, when it also occurred on hillslopes used for pasture, where soil conductivity was low. The bedrock-soil percolation, simulated by a threshold mechanism, further increased the non-linearity of the rainfall-runoff processes. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article presents a study on the patterns of seepage losses and related groundwater recharge patterns during a typical Mediterranean runoff event at the scale of a ditch located above a shallow water table. Its aim is to evaluate the influence of ditches network on groundwater recharge and contamination by surface waters in farmed areas where severe problems of water contamination occur. Results show that seepage losses during a runoff event in a ditch can rapidly lead to a significant recharge of a shallow water table. It also points that the patterns of water table recharge and contamination in Mediterranean catchments with dense network vary largely in space and time, and will require dense monitoring networks to estimate the evolution of the average contamination levels.

The article discusses a study about the spatial and temporal variability of the hydrological response in a small Mediterranean research catchment, Cal Rodó. The main purpose of the study is to examine the rainfall-runoff relationship in the catchment in an attempt to characterize the non-linearity of its hydrological response. The greater seasonality of the hydrological response of the catchment was manifested at the event scale. The spatial and temporal non-linearities of the rainfall-runoff relationship observed in the catchment and reported in other Mediterranean catchments have direct implications on hydrological modelling.