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• A cequias de careo constitute the oldest managed aquifer recharge system of Europe. • In Middle Ages, Muslims derived meltwater and recharged it through uncoated channels. • The managed aquifer recharge technique helped ensure water availability downstream. • This case study illustrates a paradigm that should be used in future water crises. • This MAR technique may prove key for adaptation to climate change in Alpine regions. In Sierra Nevada (southern Spain), the highest mountain range in southern Europe, the application of an ancestral Integrated Water Resources Management system (IWRM), based on the conjunctive use of groundwater and surface water, provides water resources for irrigation and supply in the driest months of the year in this semiarid mountain region. Meltwater is derived from the headwaters of the mountain streams and rivers through a set of uncoated channels excavated in the ground (locally known as acequias de careo) to infiltrate at the upper part of the valleys. Water infiltrated along the acequias de careo slowly flows down the hillsides, through the weathered zone of the hard rock aquifer and the glacial and periglacial sediments. The recharge accomplished through this Managed Aquifer Recharge technique (MAR) activates numerous springs located halfway down the hillside and increases the base flow of the rivers. In this study, focused on a careo channel located on the southern slope of Sierra Nevada called Acequia de El Espino, different archaeological, sedimentological, geophysical and hydrogeological techniques are applied to determine the age and the efficiency of this ancestral example of a MAR and IWRM system. Results suggest that the acequias de careo may be the oldest MAR system in Europe, and that this MAR technique could be applied in other high mountain alpine watersheds to mitigate the effects of climate change. [ABSTRACT FROM AUTHOR]

• Incorporating observations into snow models improves streamflow predictions. • Best performances with a bias-detecting method within energy-balance snow models. • Snow-hydrological model frameworks benefit at a variety of Alpine catchments. Snow is an important component of the water balance of many mountain watersheds worldwide. In a warming climate, snowmelt modeling and consequent soil water input, is often challenged by complex conditions such as rain-on-snow situations. This is why detailed physics-based snow models are increasingly being used. These models however have much higher input data requirements, where in many cases accurate forcing fields are very difficult to provide. This study investigates whether the latest advances in the development of snow model framework actually translate into improved discharge simulations. To this end we integrated a distributed multi-layer energy-balance snow model with two recently developed methods of updating snow model mass and energy fluxes using snow observations to improve snow accumulation and depletion predictions. Surface water input from these simulations was used as input for subsequent streamflow modeling of 25 catchments in the Swiss Alps over four hydrological years. Our analysis clearly demonstrates the benefits of accurate snow simulations for hydrological modeling in Alpine catchments. Simulations that included the flux updates improved streamflow predictions, and offered best performance at high elevation, where snow most prominently affected watershed hydrology. These results were consistently achieved when analyzing model performance over entire hydrological years, over the snowmelt season only, and for individual events. [ABSTRACT FROM AUTHOR]

• Contributions of climate variability and land use and land cover changes to reductions of runoff were determined. • The change of precipitation has a positive impacts on the runoff variation, whereas the watershed change has a negative impacts on the runoff variation. • Landuse changes are the main reason for runoff reduction in the Bahe River watershed of the Qinling Mountains. Climate change and human activities are the two major driving factors that affect the hydrological cycle. This study analysed the streamflow changes during 1958–2015 and related them to climate and land surface alterations in the Bahe River watershed of the Qinling Mountains by using the Budyko framework. The Pettit test method was used to investigate abrupt changes, and the Mann–Kendall test method was employed to assess monotonic trends. The results showed that annual runoff exhibited a significant declining trend, with a change point found in 1989. Annual precipitation and potential evapotranspiration showed decreasing and increasing trends, respectively, but neither were significant. The hydrological responses were more sensitive to land surface alterations than climate variability. The contributions of climate change and land surface alterations to changes in runoff were 25.50 and 74.50%, respectively. The watershed characteristics parameter played a primary role, which indicates that runoff variability is most sensitive to land surface alterations due to vegetation change and land use and land cover change. This study could provide a scientific basis for how to effectively and efficiently mitigate changes in water resources and guide measures to be implemented in the region under future climate change. [ABSTRACT FROM AUTHOR]

The interface between oxic surface water and anoxic groundwater plays an important role in trace element cycling in mountains streams. In this investigation, stream water and shallow groundwater were sampled in a semiarid mountain catchment at Red Canyon, Wyoming, USA to evaluate variability in redox conditions and trace element concentrations. Samples were collected in July 2013 during summer baseflow conditions and in May 2014 during snowmelt runoff. Field measurements showed dissolved oxygen-saturated stream water and anoxic groundwater, with relatively higher pH in surface water. Groundwater and surface water chemistry were remarkably similar during both the summer and spring sampling events, indicating overall stability of the oxic/anoxic transition and trace element concentrations. Similar stable water isotope values indicate a close connection between the surface water and groundwater (δ18O and δD ranged from − 18.1 to − 18.9‰ and from − 140 to − 147‰, respectively). Concentrations of most trace and major elements were a factor of two higher in groundwater relative to surface water. Notably, Mn, Fe, and Ce concentrations were 7–90-fold higher in groundwater relative to surface water. In contrast, As, Se, and V concentrations were 3–30-fold lower in groundwater relative to surface water, likely due to pH- and redox-driven changes in speciation and sorption. This study is important for characterizing trace element cycling in mountainous areas, where measurements are rare, and has implications for furthering understanding of the key biogeochemical processes that occur during groundwater–surface water interactions. [ABSTRACT FROM AUTHOR]

The Soil Water Assessment Tool (SWAT) is employed throughout the world to simulate watershed processes. A limitation of this model is that locations of saturation excess overland flow in hilly and mountainous regions with an impermeable layer at shallow depth cannot be simulated realistically. The objective of this research is to overcome this limitation with minor changes in the original SWAT code. The new approach is called SWAT-with-impervious-layers (SWAT-wil). Adaptations consisted of redefining the hillslope length, restricting downward percolation from the root zone, and redefining hydrologic response units (HRUs) such that they are associated with the landscape position. Finally, input parameters were chosen such that overland flow from variable saturated areas (VSAs) corresponds to the variable source interpretation of the Soil Conservation Service (SCS) curve number runoff equation. We tested the model for the Town Brook watershed in the Catskill Mountains. The results showed that the discharge calculated with SWAT-wil agreed with observed outflow and results simulated with the original SWAT and SWAT-hillslope (SWAT-HS) models that had a surface aquifer that transferred water between groups of HRUs. The locations of the periodically saturated runoff areas were predicted by SWAT-wil at the right locations. Current users can utilize the SWAT-wil approach for catchments where VSA hydrology predominates. [ABSTRACT FROM AUTHOR]

Evaporation of precipitation from plant surfaces, or interception, is a major component of the global water budget. Interception has been measured and/or modelled across a wide variety of forest types; however, most studies have focused on mature, second‐growth forests, and few studies have examined interception processes across forest age classes. We present data on two components of interception, total canopy interception (Ei) and litter interception—that is, Oi + Oe horizon layers—(Eff), across a forest age chronosequence, from 2 years since harvest to old growth. We used precipitation, throughfall, and stemflow collectors to measure total rainfall (P) and estimate Ei; and collected litter biomass and modelled litter wetting and drying to estimate evaporative loss from litter. Canopy Ei, P minus throughfall, increased rapidly with forest age and then levelled off to a maximum of 21% of P in an old‐growth site. Stemflow also varied across stands, with the highest stemflow (~8% of P) observed in a 12‐year‐old stand with high stem density. Modelled Eff was 4–6% of P and did not vary across sites. Total stand‐level interception losses (Ei + Eff) were best predicted by stand age (R2 = 0.77) rather than structural parameters such as basal area (R2 = 0.49) or leaf area (R2 < 0.01). Forest age appears to be an important driver of interception losses from forested mountain watersheds even when stand‐level structural variables are similar. These results will contribute to our understanding of water budgets across the broader matrix of forest ages that characterize the modern forest landscape. [ABSTRACT FROM AUTHOR]

Permafrost and frozen ground play a critical role in the transfer of water and solutes from the landscape to the stream, and in biogeochemical cycling by acting as a cold season or semi-permanent acquitard. Conceptual models of permafrost hydrology have been well defined for over 40 years, yet renewed interest in the face of climate change and rapid degradation of frozen ground has provided an opportunity to revisit previous paradigms. At the same time, new instruments and techniques to understand coupled hydrological and biogeochemical processes have emerged, providing a more nuanced view of northern catchments. In this presentation, multi-year high frequency data sets of water, specific conductance (SpC) and chromophoric dissolved organic matter (CDOM) from Granger Creek, an instrumented alpine watershed with discontinuous permafrost within the Wolf Creek Research Basin, Yukon Territory, Canada, is presented. Snowmelt and rainfall-runoff events were delineated over multiple years and sub-hourly data was used to generate hysteresis loops for several dozen events. The direction and magnitude of these loops for Q-SpC and Q-CDOM suggest strong seasonal controls on the mechanisms of solute export, which vary for weathering ions compared with dissolved organic matter. Dissolved solutes (as represented by SpC) are largely diluted during freshet and storm events, with Q-SpC hysteresis being greatest during period of low-flow in mid-summer when SpC was large. In contrast, CDOM largely exhibited a mobilization signal with large event and inter-annual variability in hysteresis patterns. In both cases, there were unique signals related to season: freshet, mid-summer low flow and fall wetting. High-frequency and hysteresis direction and magnitude suggest changing proximal and distal sources of solutes and organic material in response to active layer thickening, soil moisture and precipitation intensity; highlighting spatial connections among landscape units not previously reported. Evaluation of these patterns at the headwater scale provides alternate hypotheses for how permafrost landscapes may respond to a changing climate. [ABSTRACT FROM AUTHOR]

The Italian Alpine region holds the largest share of hydropower production in Italy, accounting for more than 75% of the national hydropower installed capacity, and satisfying about 20% of the daily electricity demand in Italy. Furthermore, storage hydropower plays a major role, accounting for about 60% of installed capacity and mean annual hydropower production in the region.From a modeling perspective, simulation of storage hydropower systems represents an open challenge in hydrology due to the difficulties in acquiring technical information of each system. Therefore most of the work done so far focuses on run-of-the-river systems, adopt indirect proxies of regional storage hydropower production (e.g. gross potential estimates, selected quantiles of the streamflow flow duration curves), or limit the analysis to a particular system.In this study, we present an application of HYPERstreamHS model in the Adige river basin, located in the south-eastern part of the Alps. HYPERstreamHS is a distributed hydrological model specifically designed to simulate in detail the interactions between anthropogenic infrastructures (such as reservoirs and diversion channels) and the natural hydrologic system. The conceptual model of the Adige river basin (drainage area of about 10500 square kilometers closed at Trento gauging station) includes the presence of 30 storage reservoirs and 27 large hydropower plants (i.e., with average nominal capacity larger than 3 MW). A multi-site calibration procedure has been performed by comparing observed and simulated streamflow time series during the period 2000-2013, achieving an overall Nash-Sutcliffe efficiency of 0.82. Afterwards, the hydropower production module has been successfully validated against historical hydropower production time series in the Noce river basin, a large tributary of the Adige river with a drainage area of about 1300 square kilometers that hosts 12% of the installed capacity of the entire Adige basin. The resulting modelled hydropower production differed from the observed data by 6%. The implementation and validation of the remaining hydropower systems in the Adige watershed is currently ongoing. [ABSTRACT FROM AUTHOR]

In the mountain-plain transitional areas, the possible sources of the groundwater recharge arethe rainfall on the plain and the surface water/ the groundwater at the headwaters. Previously,the mountain block recharge has been supposed to be not dominant, because the faults /geological borders generally exist at the boundary between the mountain and theplain. In Ono basin, Fukui Prefecture, north-west Japan, previous papers showedthat the surface water from the mountain is a dominant source of the groundwaterin the plain. However, the observed groundwater contour map suggests that themountain block recharge also would contribute. Thus, we evaluated the role of themountain block recharge for the basin groundwater using sulfur hexafluoride (SF6)as atracer. Ono Basin itself has an area of approximately 75 km2, and whole watershed of Ono Basinhas an area of 942.5 km2 with an altitude ranging from 154.8 m to 1972.1 m. We sampledthe groundwater at 20 monitoring wells and the surface water at 2 locations ofRiver Mana at Ono in July and August 2018. We also observed the depth of thegroundwater table at the wells to construct the groundwater contour map in thebasin. The SF6 concentration, inorganic constituent concentrations, stable isotopiccompositions of the deuterium and the oxygen-18 were determined on all watersamples. The SF6 concentration in the groundwater ranged from 3.1 fmol to 6.3 fmol, whereas thatof the river water ranged from 2.6 fmol to 3.2 fmol. Also, the SF6 concentration of thegroundwater was lower in the southwestern area of the basin as compared with that ofnorthern area and area nearby the river, suggesting the contribution of mountain blockrecharge is dominant in the southwestern area of the basin. We applied an End MemberMixing Analysis (EMMA) using SF6 as a tracer and evaluated the contribution ratio of themountain block recharge to the total recharge in the basin. The contribution of themountain block recharge was estimated to be ranging from 19% to 99%, whereasthat of the river water was estimated to be ranging from 1% to 81%. Especially,the mountain block recharge ratio showed more than 95% at the mountain-plaintransitional area in the southwestern area of the basin. Our results indicate that themountain block recharge is an important recharge source of groundwater in the basin. [ABSTRACT FROM AUTHOR]

The formosan land-locked salmon is one of the representative but endangered species in Taiwan and the first-order stream of Yushen Creek in Chichiawan Watershed, Taiwan is the major habitat for the salmons. Unfortunately, the intensive water exchanges beneath the streambed caused the creek to cease flow, and the fragmented creek could not provide a sustainable environment for the rehabilitation and the population of salmon was significantly reduced. To comprehensively understand the mechanisms of surface water and groundwater interaction and mitigate the effect of fragmentation on the salmon habitat, the tracer tests and numerical models were conducted to characteristic hyporheic flux exchanges beneath the stream. Seven observation wells and seven piezometers along the stream were installed to provide long-term water levels, temperatures, and electrical conductivities of surface water and groundwater. Five tracer tests from April, 2017 to May, 2018 were conducted at different sections of reach to delineate the horizontal and vertical hyporheic flow paths and seepage flow directions through the breakthrough curves. OTIS and VS2DT were selected to simulate the concentration variations in the stream and streambed, respectively and quantify the hydraulic characteristics of hyporheic zone. The estimated storage zones and exchange coefficients by the OTIS model were used to mimic the hyporheic cells and fed into the VS2DT model to identify the hyporheic and seepage flows. The simulated results revealed that the first-order stream has frequent flux exchanges beneath a high porosity gravel streambed but this intensive interaction reduces with the existence of confluences and the high level of baseflow. The results also demonstrated the effect of topography on the flow path that water flows out of the upstream wetted channel and back into downstream wetted channel to avoid the areas of step-riffle. Finally, the hydraulic characteristics of streambed, streamflow, and morphology of stream should be considered to mitigate the fragmentation when conducting the river restoration of the first-order stream in the alpine watershed. [ABSTRACT FROM AUTHOR]

Numerical simulators developed over recent years have the capability of simulating the physical subsurface processes that occur in cold regions associated with flow of water through geologic fabrics containing seasonal or permanent subsurface ice. These are the powerful tools required for analyses that develop basic understanding of cryohydrogeologic processes and to help understand possible impacts of human activities and infrastructure and changes in climate on water quantity, water quality, surface morphology, and ecosystems. One of the earliest-developed cryohydrogeology simulation tools is the U.S. Geological Survey (USGS) SUTRA saturated-unsaturated groundwater flow and energy transport code. SUTRA was first developed in the 1980's and was enhanced in 2006 to simulate saturated freeze/thaw processes and more-recently saturated-unsaturated freeze/thaw processes. This simulator is informally known as the SutraICE code, and it has been used in USGS cooperative projects with co-authors both within and outside USGS to study a variety of cold-regions systems in the ensuing years, as described below. SutraICE has been employed to study seasonal ground ice in peatlands and bogs, groundwater discharge controlling fish habitats in streams (thermal refugia), groundwater discharge and baseflow in alpine watersheds (where quantity and timing may be impacted by climate change), and soil freezing dynamics at high latitudes. SutraICE has also been employed to study processes in permafrost terrains including lake formation and sub-lake taliks, permafrost-vegetation interaction, active-layer dynamics, groundwater flow and baseflow to streams, development of perennial thaw zones (taliks) and carbon mobilization potential, permafrost-groundwater-surface water relations and ecology in arctic water tracks, permafrost peatlands and bogs, climate change impacts on permafrost distribution and fate, and for basic studies of the dynamics of permafrost-groundwater processes. In addition, SutraICE is being used to study glaciers, firn and snow, focusing on firn aquifers in Greenland, and, meltwater recharge fate and ice-layer formation in firn. SutraICE also has had technological applications including freeze/thaw groundwater simulation code intercomparison and ground-truthing geophysical inversion approaches for defining subsurface ice content from electrical measurements. These studies have provided basic new knowledge of cryohydrogeologic system dynamical behavior and have led to improved understanding of practical implications in a variety of cold-regions settings, highlighting the great value of numerical simulation approaches for cryohydrogeologic systems analysis. [ABSTRACT FROM AUTHOR]

The interaction between river and streambed is considered as a fundamental role in the functioning of riparian ecosystems. The endangered Formosan landlocked salmon have been successfully rehabilitated in Yusheng Creek, the first-order stream in the alpine watershed of Chichiwan Creek, Taiwan. However, the stream fragmentation, no surface streamflow, seriously reduced the salmon population, hampering the restoration work. The utility of combining high spatial and temporal resolution of distributed temperature sensing (DTS) technology and field installation of monitoring wells were demonstrated to comprehensive understand the exchange process and mitigate the effect of fragmentation on endangered salmon. The DTS measurements was conducted on the length of the 1,250 m reach covering the fragmented reach of creek from 7-13 November 2018. The monitoring wells provided the long-term water levels and streambed temperatures to analyze the dynamic behavior of hydraulic characteristics of streambed. The results showed that the DTS enabled to detect the locations of groundwater downwelling/upwelling and hyporheic exchange along the study reach. The temporal interactive processes between stream and groundwater from continuous to ceasing flow were also detected. Due to intensive rainfalls and stream fragmentation, the spatial and temporal changes of streambed in vertical hydraulic conductivities were significant. DTS measurements demonstrated significant impact of groundwater and hyporheic inflows on reducing the maximum stream water temperature by 1-2oC in November, 2018. These results implied that the downstream stream has the potential as the thermal refuge for the salmon and the fragmentation can be mitigated through the river restoration to significantly increase the salmon population. [ABSTRACT FROM AUTHOR]

Large-scale Hydrological Models (LHMs) are increasingly used in studies concerning the water cycle at synoptic, continent, and global scales. These models are not constrained to reproduce hydrological processes and streamflow at the local scale, i.e. the scale at which water resources are managed.In the present study, we evaluated suitable modifications of the Community Land Model v3.5 (CLM3.5), which improve streamflow reproduction in a relatively large Alpine catchment: the Adige river basin, south-eastern Alps with a drainage area of about 10500 km2 at the Trento gauging station. In particular, we added to CLM3.5 a simple module dealing with deep infiltration to aquifers and return flow, and replaced the grid based routing scheme with the multi-scale grid independent scheme embedded in the HYPERstreamHS hydrological model. The performance of a calibrated run of HYPERstreamHS stand-alone model in reproducing observed streamflow at the Trento gauging station was also evaluated to provide a benchmark for assessing the effectiveness of the introduced parameterizations of deep infiltration, return flow and streamflow routing. Note, all simulation runs were informed by the same meteorological forcing.Runoff computed by CLM3.5 with the HYPERstream routing scheme improved the performances of the Nash Sutcliffe Efficiency (NSE) from -0.05 (uncalibrated CLM3.5 run) to 0.15. Furthermore, results indicate that, at least in the case of the Alpine watershed considered in this study, low NSE values are due to an underestimation of the water recharging deep aquifers and not re-entering the river network in CLM3.5. In addition, simulations using HYPERstreamHS informed by actual evapotranspiration outputs as provided by CLM3.5 showed a good agreement with observations (NSE = 0.61), which is very close to the performance obtained with the stand-alone run of HYPERstreamHS (NSE=0.65), thus suggesting that the land surface energy and mass balance is correctly simulated in CLM3.5 model also at the local scale.Results of this study suggest that a significant improvement of the performance of CLM3.5 in reproducing observed streamflow time series at the local scale may be achieved by replacing the grid based routing scheme with a more accurate scale-independent routing scheme and adding a simple parametrization of deep infiltration, with the latter producing the most significant improvement. [ABSTRACT FROM AUTHOR]

European awareness to natural based approaches for resilience to hydro-meteorological effects is still increasing. Many finished or ongoing projects at urban scale provide a large scale and fully replicable demonstration actions for the application of Nature-Based Solutions to address climate change impacts and improve the quality of life and urban resilience. However, in rural and mountainous regions, where hydro-meteorological risk is amplified, the occurrence of extreme weather events can lead to catastrophic consequences that can dramatically change the ecosystem with irreversible damages at catchment scale. The main objective of the H2020 project PHUSICOS is to demonstrate that nature-based/nature-inspired solutions for reducing the risk of extreme weather events in particularly vulnerable areas such as rural mountain landscapes, are technically viable, cost-effective and implementable at regional scale. Furthermore, that they increase the ecological, social and economic resilience of local communities. To this aim, three large-scale demonstration sites have been selected respectively in Italy, France/Spain/Andorra and Norway as representative of hydro-meteorological hazards, vegetation, topography and infrastructure throughout rural and mountainous regions in Europe. The first demonstration projects will be implemented in 2019. Within the four-year duration of PHUSICOS the innovative key actions will be: • create a participative process with a diverse range of stakeholders through a Living Lab approach with service innovation at the demonstration sites focusing on new ways of co-designing sustainable management services, • design a comprehensive framework for comparative analysis and monitoring tools to evaluate the performance of various nature-based solutions, • explore ways to enhance the effectiveness of the implementation of nature-based solutions in the context of governance innovation, the planning and policy mechanisms for sustainable use and management of land, water, and natural resources in rural areas and their impacts at the local and wider watershed scale,• create a knowledge co-generation platform using learning arena innovation, including the use of serious game (or social simulation) approaches, to encourage knowledge exchange through the identification of possible nature-based solutions, co-development of scenarios and modelling their impacts at the demonstration sites, as well as training of local decision makers and contractors to implement innovative nature-based solutions.• establish a comprehensive state-of-the-art evidence-base and data platform concerning nature-based solutions through product innovation, providing overview of tools and best practices tested at the demonstration sites in different contexts and suitable for replication and up-scaling towards future implementation.In conclusion, the aim of PHUSICOS is to demonstrate that nature-based/nature-inspired solutions are suitable, technically viable, cost-effective and implementable at regional scale for reducing the risk of extreme weather events. Furthermore, they improve the human well-being and quality of life, as well as social economic resilience of local communities. [ABSTRACT FROM AUTHOR]

Peatlands in mountains are small and patchy. However, they are biogeochemical hotspots forcarbon cycle, and disproportionally contribute to organic carbon transfer to headwaterstreams. In a harsh mountainous climatic and hydrologic context, this study aims atidentifying parameters controlling DOC concentration fluctuations at the outlet ofpeatlands. In the French Pyrenees, the variability of the DOC concentration was investigated at theoutlet of a fen site (1343 m.a.s.l., 4,7 ha) for four years, and at the outlet of a bog site(706 m.a.s.l, 5,3 ha) for a year and a half. High frequency (30 min) in situ fDOM(fluorescence of dissolved organic matter) sensors were deployed as proxies for DOCconcentration. To identify controlling factors on DOC concentration, high frequencydata including meteorological parameters and stream discharge were collected atboth sites. Water table level and the water temperature were also monitored at ahigh frequency in piezometers wells at different representative locations in eachpeatland. High frequency monitoring reveals a strong variability in DOC concentration at bothsites. Most of this variability is related to short (∼30 hours) DOC concentration peaksinitiated by precipitation events. Lower mean DOC concentration (1.8 mg.L−1) but strongerDOC increases (5,1 times mean concentration) are observed at the fen site compared to thebog site (mean concentration of 5.9 mg.L−1, and increases of 1,8 times). At both sites, DOCconcentration increases are not proportional to the discharge increases observed at the outlet.However, peak analysis reveals that DOC concentration increases are linearly correlated tothe averaged water table rises of the whole site. The slope of the linear models differsbetween sites. Master recession curve analysis was used to classify water tablesignals from each piezometer well depending on their hydraulic conductivity. Thishighlights clear differences in hydraulic conductivity between the bog and the fensites, explaining their different DOC concentration peak models. Fen are flashysystems, characterized by low baseline DOC and strong peaks, when bog sustainhigher baseline DOC concentrations but weaker peaks. Whatever peatland types,this study shows that re-wetting of the non-saturated peat layer is a key factor inthe DOC transfer processes from peatland to stream in mountainous watersheds. [ABSTRACT FROM AUTHOR]

We propose an experimental setup to measure soil erosion and related it with sediment transport using rainfall simulator on a large plots experimental area. Experiments were carried out in fulfilment of the HERASE project, aimed at investigating the seasonal variations of soil erosion in the Oglio basin, an Alpine and Pre-alpine watershed with an area of about 1800 km2, and maximum elevation of 3.538m a.s.l. Namely some rainfall simulation experiments were carried out to assess water erosion under three different scenarios, on in situ plots having same soil and slope, but with different soil coverage and initial moisture condition. In particular, two experiments were carried out on a grassland plot covering an area of 144m2, one considering an undisturbed initial soil moisture condition and the other on a wet soil. The third experiment plot, having the same soil and slope of the previous, and covering an area of 72m2, was set up in the pine forest underwood area. The duration of the three experiments were respectively of 18 minutes, 30 minutes and 30minutes and rainfall intensity was set equal to 70mm/h, accordingly to a 200 return period storm. The plots were properly designed to ensure a correct as possible measure of surface runoff, and transported sediments were collected at 1 minute steps. Suspended sediment, and particle size analysis were carried out ex-post. Our results show a different behaviour of the two analysed plots, in terms of runoff generation and sediment transport. The runoff peak on grassland ranged from 0.018l/s for the undisturbed condition, to 0.09l/s with wet initial condition, while the peak in sediment transport, slowly delayed with respect to the runoff peak, was 1,7 times bigger in wet conditions. In the third experiment, peak runoff was 0.9l/s (10 times bigger than the peak runoff on wet grassland), and constant until the end of simulated rainfall, and took five minutes to run out (concentration time). The analysis on sediment shows an initial slush, where pine needles composed the majority of sediment. Then, after the sediment reached the peak of 350mg/s after about 9 minutes from the beginning of the experiment, it decreased rapidly to an almost constant value of 50mg/s. Interpretations on experiment results with different formulations and a comparison with similar analyses carried out in the Alpine area of Italy are proposed. [ABSTRACT FROM AUTHOR]

In this study, a new Grid-Xinanjiang model, which considering the spatial variability of grid cell topographical information and soil moisture storage capacity, was developed to simulate the flash flood for small mountain watersheds. The soil moisture storage capacity of each grids was calculated by using the Curve Number of SCS-CN (Soil Conservation Service) model. The model was performed at 90m grid cells, which highlights the well representing of the sub-grid variability. The developed model was applied to six typical small mountain watersheds in different provinces of China for flash flood simulations. The performance of the Grid-Xinanjiang model was compared with that of the commonly used HEC-HMS model. The results show that the Grid-Xinanjiang model performs a little better than the HEC-HMS model in terms of the estimates of streamflow and the model efficiency coefficient. Most of the qualified ratios relative to runoff depth, peak flow, and peak time for the Grid-Xinanjiang model in the applied watersheds are more than 95%. Combining the critical discharge and the antecedent soil moisture condition, the newly developed Grid-Xinanjiang model can be used to calculate the flash flood warning critical rainfall for Chinese small mountain watersheds. [ABSTRACT FROM AUTHOR]

The aim of this work is to simulate hydraulic transfers and upstream erosion sources in steep and erodible mountain watersheds with a physically-based model. In such environments, immature debris flows and shallow landslides can be the largest sources of sediments transported at the outlet. To simulate these phenomenon, a gravity-driven erosion model and a 1D vertical infiltration model have been developed in the TELEMAC 2D computation code. In this new erosion model, the motion of the granular flow is described with a fully dynamic system and a Coulomb-like bottom friction treatment. The debris flow model is first evaluated to experimental channel data (Iverson et al. 2010). Then, the model is confronted to field data on a real catchment (Draix, in the Southern French Alps). First, the initial soil moisture in the infiltration model is successfully calibrated in order to simulate six different rainy events. Then, the new erosion model is applied at the catchment scale (about 1 km²). The results of the simulations show that the sediment fluxes at the outlet are well reproduced, as are the total volumes exported. The parameters used in the model for each event are also consistent with the discharge/concentration relationships measured, and the origin of the sediments arriving at the outlet in the model corresponds well to the interpretations made from the measurements (Mathys 2006). [ABSTRACT FROM AUTHOR]

La Trucha is a small (~ 1.9 km2), mountainous (~ 1300 m a.s.l.) granitic drainage basin, demonstrative of hundreds of second-order basins in the Achala Batholith of the Sierras Pampeanas of Córdoba, Argentina. Dominated by physical weathering and a weathering-limited denudation regime, the coarse- and fine-grained regolith has shown scant geochemical differences with the country rock. Erosion and sediment transport mainly occurs during torrential rain events (austral summer), whereas surface waters classify as dilute (750 < TΣ+ < 375 µeq L−1) or very dilute (375 < TΣ+ < 185 µeq L−1) water types. The dynamics of chemical weathering at La Trucha was approached through the use of major dissolved chemical components, comparing the performance of different methodologies in its assessment: mineral stability diagrams (i.e., chemical equilibria), the RE chemical weathering index, ternary diagrams, and PHREEQC inverse modeling. The latter approach allowed to probe into subtleties of the geochemical processes indicating that, besides the morphological dependency on mineral hydrolysis/dissolution or precipitation, there is a marked seasonal control that promotes or limits the occurrence of geochemical reactions. [ABSTRACT FROM AUTHOR]

A correction to the article "Forest-Water Dynamics Within a Mountainous Catchment in Austria" that was published online on April 8, 2015 is presented.

A letter to the editor is presented concerning the International Network for Alpine Research Catchment Hydrology which was launched in 2015 by the World Climate Research Programme's Global Energy and Water Exchanges project to improve the predictability of water supplies from mountainous areas.

The author reflects on the importance of the natural springs in the hilly tracts of Joda-Badbil-Koira area of Keonjhar-Sundargarh District in Orissa, India. He argues that the discharge of a spring is controlled by rainfall, land use, vegetation and geomorphology of a recharged zone in a mountain watershed. He thinks that the lineaments produced by joints, fractures and faults play a significant role in the hydrogeological regime of a catchments.

In many watersheds, lakes and streams are hydrologically linked in spatial patterns that influence material transport and retention. We hypothesized that lakes affect stream nutrient cycling via modifications to stream hydrogeomorphology, source-waters, and biological communities. We tested this hypothesis in a lake district of the Sawtooth Mountains, Idaho. Uptake of NO3- and PO4-3 was compared among 25 reaches representing the following landscape positions: lake inlets and outlets, reaches >1-km downstream from lakes, and reference reaches with no nearby lakes. We quantified landscape-scale hydrographic and reach-scale hydrogeomorphic, source-water, and biological variables to characterize these landscape positions and analyze relationships to nutrient uptake. Nitrate uptake was undetectable at most lake outlets, whereas PO4-3 uptake was higher at outlets as compared to reference and lake inlet reaches. Patterns in nutrient demand farther downstream were similar to lake outlets with a gradual shift toward reference-reach functionality. Nitrate uptake was most correlated to sediment mobility and channel morphology, whereas PO4-3 uptake was most correlated to source-water characteristics. The best integrated predictor of these patterns in nutrient demand was % contributing area (the proportion of watershed area not routing through a lake). We estimate that NO3- and PO4-3 demand returned to 50% of pre-lake conditions within 1-4-km downstream of a small headwater lake and resetting of nutrient demand was slower downstream of a larger lake set lower in a watershed. Full resetting of these nutrient cycling processes was not reached within 20-km downstream, indicating that lakes can alter stream ecosystem functioning at large spatial scales throughout mountain watersheds. [ABSTRACT FROM AUTHOR]