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  • 1. Addor, Nans
    et al.
    Seibert, J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Bias correction for hydrological impact studies: beyond the daily perspective2014Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, nr 17, s. 4823-4828Artikel i tidskrift (Övrigt vetenskapligt)
  • 2. Ali, Genevieve
    et al.
    Tetzlaff, Doerthe
    McDonnell, Jeffrey J.
    Soulsby, Chris
    Carey, Sean
    Laudon, Hjalmar
    McGuire, Kevin
    Buttle, Jim
    Seibert, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Shanley, Jamie
    Comparison of threshold hydrologic response across northern catchments2015Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, nr 16, s. 3575-3591Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nine mid-latitude to high-latitude headwater catchments - part of the Northern Watershed Ecosystem Response to Climate Change (North-Watch) programme - were used to analyze threshold response to rainfall and snowmelt-driven events and link the different responses to the catchment characteristics of the nine sites. The North-Watch data include daily time-series of various lengths of multiple variables such as air temperature, precipitation and discharge. Rainfall and meltwater inputs were differentiated using a degree-day snowmelt approach. Distinct hydrological events were identified, and precipitation-runoff response curves were visually assessed. Results showed that eight of nine catchments showed runoff initiation thresholds and effective precipitation input thresholds. For rainfall-triggered events, catchment hydroclimatic and physical characteristics (e.g. mean annual air temperature, median flow path distance to the stream, median sub-catchment area) were strong predictors of threshold strength. For snowmelt-driven events, however, thresholds and the factors controlling precipitation-runoff response were difficult to identify. The variability in catchments responses to snowmelt was not fully explained by runoff initiation thresholds and input magnitude thresholds. The quantification of input intensity thresholds (e.g. snow melting and permafrost thawing rates) is likely required for an adequate characterization of nonlinear spring runoff generation in such northern environments.

  • 3.
    Ameli, A. A.
    et al.
    Univ Western Ontario, Dept Biol, Biol & Geol Sci Bldg, London, ON N6A 3K7, Canada.;Univ Saskatchewan, Global Inst Water Secur, Saskatoon, SK, Canada.;Uppsala Univ, Dept Earth Sci Air Water & Landscape Sci, Uppsala, Sweden..
    McDonnell, J. J.
    Univ Saskatchewan, Global Inst Water Secur, Saskatoon, SK, Canada.;Univ Aberdeen, Sch Geosci, Aberdeen, Scotland..
    Bishop, Kevin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Uppsala centrum för hållbar utveckling, CSD Uppsala. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära. Swedish Univ Agr Sci SLU, Dept Aquat Sci & Assessment, Uppsala, Sweden..
    The exponential decline in saturated hydraulic conductivity with depth: a novel method for exploring its effect on water flow paths and transit time distribution2016Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 30, nr 14, s. 2438-2450Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The strong vertical gradient in soil and subsoil saturated hydraulic conductivity is characteristic feature of the hydrology of catchments. Despite the potential importance of these strong gradients, they have proven difficult to model using robust physically based schemes. This has hampered the testing of hypotheses about the implications of such vertical gradients for subsurface flow paths, residence times and transit time distribution. Here we present a general semi-analytical solution for the simulation of 2D steady-state saturated-unsaturated flow in hillslopes with saturated hydraulic conductivity that declines exponentially with depth. The grid-free solution satisfies mass balance exactly over the entire saturated and unsaturated zones. The new method provides continuous solutions for head, flow and velocity in both saturated and unsaturated zones without any interpolation process as is common in discrete numerical schemes. This solution efficiently generates flow pathlines and transit time distributions in hillslopes with the assumption of depth-varying saturated hydraulic conductivity. The model outputs reveal the pronounced effect that changing the strength of the exponential decline in saturated hydraulic conductivity has on the flow pathlines, residence time and transit time distribution. This new steady-state model may be useful to others for posing hypotheses about how different depth functions for hydraulic conductivity influence catchment hydrological response.

  • 4.
    Andersson, Jafet
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Traore, Farid
    Gustafsson, David
    SMHI, Forskningsavdelningen, Hydrologi.
    Ali, Abdou
    Process refinements improve a hydrological model concept applied to the Niger River basin2017Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 31, nr 25, s. 4540-4554Artikel i tidskrift (Refereegranskat)
  • 5.
    Andersson, Jan-Olov
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Nyberg, Lars
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Centrum för klimat och säkerhet.
    Spatial variation of wetlands and flux of dissolved organic carbon in boreal headwater streams2008Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, nr 22, s. 1965-1975Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to investigate the relation between water chemistry and functional landscape elements, spatial data sets of characteristics for 68 small (0·2–1·5 km2) boreal forest catchments in western central Sweden were analysed in a geographical information system (GIS). The geographic data used were extracted from official topographic maps. Water sampled four times at different flow situations was analysed chemically. This paper focuses on one phenomenon that has an important influence on headwater quality in boreal, coniferous forest streams: generation and export of dissolved organic carbon (DOC). It is known that wetland cover (bogs and fens) in the catchment is a major source of DOC. In this study, a comparison was made between a large number of headwater catchments with varying spatial locations and areas of wetlands. How this variation, together with a number of other spatial variables, influences the DOC flux in the streamwater was analysed by statistical methods. There were significant, but not strong, correlations between the total percentages of wetland area and DOC flux measured at a medium flow situation, but not at high flow. Neither were there any significant correlations between the percentage of wetland area connected to streams, nor the percentage of wetland area within a zone 50 m from the stream and the DOC flux. There were, however, correlations between catchment mean slope and the DOC flux in all but one flow situations. This study showed that, considering geographical data retrieved from official sources, the topography of a catchment better explains the variation in DOC flux than the percentage and locations of distinct wetland areas. This emphasizes the need for high-resolution elevation models accurate enough to reveal the sources of DOC found in headwater streams.

  • 6. Aronica, Giuseppe T.
    et al.
    Apel, Heiko
    Di Baldassarre, Giuliano
    UNESCO-IHE Institute for Water Education, Delft, the Netherlands.
    Schumann, Guy J-P.
    HP - Special Issue on Flood Risk and Uncertainty2013Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 27, nr 9, s. 1291-Artikel i tidskrift (Refereegranskat)
  • 7.
    Asokan, Shilpa M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Dutta, Dushmanta
    Analysis of water resources in the Mahanadi River Basin, India under projected climate conditions2008Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 22, nr 18, s. 3589-3603Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The paper presents the outcomes of a study conducted to analyse water resources availability and demand in the Mahanadi River Basin in India under climate change conditions. Climate change impact analysis was carried out for the years 2000, 2025, 2050, 2075 and 2100, for the months of September and April (representing wet and dry months), at a sub-catchment level. A physically based distributed hydrologic model (DHM) was used for estimation of the present water availability. For future scenarios under climate change conditions, precipitation output of Canadian Centre for Climate Modelling and Analysis General Circulation Model (CGCM2) was used as the input data for the DHM. The model results show that the highest increase in peak runoff (38%) in the Mahanadi River outlet will occur during September, for the period 2075-2100 and the maximum decrease in average runoff (32·5%) will be in April, for the period 2050-2075. The outcomes indicate that the Mahanadi River Basin is expected to experience progressively increasing intensities of flood in September and drought in April over the considered years. The sectors of domestic, irrigation and industry were considered for water demand estimation. The outcomes of the analysis on present water use indicated a high water abstraction by the irrigation sector. Future water demand shows an increasing trend until 2050, beyond which the demand will decrease owing to the assumed regulation of population explosion. From the simulated future water availability and projected water demand, water stress was computed. Among the six sub-catchments, the sub-catchment six shows the peak water demand. This study hence emphasizes on the need for re-defining water management policies, by incorporating hydrological response of the basin to the long-term climate change, which will help in developing appropriate flood and drought mitigation measures at the basin level.

  • 8. Beldring, Stein
    et al.
    Gottschalk, Lars
    Rodhe, Allan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Tallaksen, Lena M.
    Kinematic wave approximations to hillslope hydrological processes in tills2000Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 14, nr 4, s. 727-745Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work has been carried out within the framework of NOPEX - a NOrthern hemisphere climate Processes land surface EXperiment. Its purpose is to describe the spatial variability of groundwater levels and soil moisture content and their influence on runoff generation in small catchments in a landscape dominated by boreal forest and till soils, which is characteristic for the Nordic countries. Kinematic wave approximations have been used to describe saturated subsurface flow and saturation overland flow in hillslopes with a thin soil layer overlying a relatively impermeable bedrock. Simultaneous analyses of catchment runoff, groundwater-table depths and soil moisture in the unsaturated zone have been performed by including the kinematic wave descriptions in a precipitation-runoff model. The results have been compared with observed hydrographs and spatial patterns of groundwater levels and soil moisture content in two small experimental catchments. Results from this study indicate that is reasonable to apply the same parameter set when describing hydrological processes in computational elements with similar characteristics at a scale of about 1 km(2) in the NOPEX area. 

  • 9.
    Bergström, Sten
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Samhälle och säkerhet.
    Interpretation of runoff processes in hydrological modelling experience from the HBV approach2015Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, nr 16, s. 3535-3545Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The process of development and application of the Hydrologiska Byrans Vattenbalansavdelning hydrological model over a time period of more than 40years is reviewed and discussed. Emphasis is on the early modelling strategy and physical considerations based on contemporary research on runoff formation processes in the drainage basin. This includes areal considerations on the catchment scale, soil moisture and evapotranspiration and storages and discharge as represented by the response function of the model. The introduction of the concept of dynamic recharge and discharge areas is also addressed as well as the modelling of snow accumulation and melt. Some operational international experiences are also addressed. Copyright (c) 2015 John Wiley & Sons, Ltd.

  • 10.
    Bergström, Sten
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Pettersson, Anna
    SMHI, Forskningsavdelningen, Hydrologi.
    Multi-variable parameter estimation to increase confidence in hydrological modelling2002Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 16, nr 2, s. 413-421Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The expanding use and increased complexity of hydrological runoff models has given rise to a concern about overparameterization and risks for compensating errors. One proposed way out is the calibration and validation against additional observations, such as snow, soil moisture, groundwater or water quality. A general problem, however, when calibrating the model against more than one variable is the strategy for parameter estimation. The most straightforward method is to calibrate the model components sequentially. Recent results show that in this way the model may be locked up in a parameter setting, which is good enough for one variable but excludes proper simulation of other variables. This is particularly the case for water quality modelling, where a small compromise in terms of runoff simulation may lead to dramatically better simulations of water quality. This calls for an integrated model calibration procedure with a criterion that integrates more aspects on model performance than just river runoff. The use of multi-variable parameter estimation and internal control of the HBV hydrological model is discussed and highlighted by two case studies. The first example is from a forested basin in northern Sweden and the second one is from an agricultural basin in the south of the country. A new calibration strategy, which is integrated rather than sequential, is proposed and tested. It is concluded that comparison of model results with more measurements than only runoff can lead to increased confidence in the physical relevance of the model, and that the new calibration strategy can be useful for further model development. Copyright (C) 2002 John Wiley Sons, Ltd.

  • 11.
    Beven, Keith
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära. Univ Lancaster, Lancaster Environm Ctr, Lancaster, England..
    Advice to a young hydrologist2016Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 30, nr 20, s. 3578-3582Artikel i tidskrift (Övrigt vetenskapligt)
  • 12.
    Beven, Keith
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    I believe in climate change but how precautionary do we need to be in planning for the future?2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 9, s. 1517-1520Artikel i tidskrift (Övrigt vetenskapligt)
  • 13.
    Beven, Keith
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    On doing better hydrological science2008Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 22, nr 17, s. 3549-3553Artikel i tidskrift (Refereegranskat)
  • 14.
    Beven, Keith
    Lancaster Environment Centre, Lancaster University, Lancaster, UK.
    On undermining the science?2006Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 20, nr 14, s. 3141-3146Artikel i tidskrift (Refereegranskat)
  • 15.
    Beven, Keith
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Preferential flows and travel time distributions: defining adequate hypothesis tests for hydrological process models2010Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, nr 12, s. 1537-1547Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This introduction to the second annual review issue of Hydrological Processes tries to put the collection of papers on preferential flows and travel time distributions into a more general context of testing models as hypotheses about how catchment systems function. It is suggested that, because of the possibilities of non-stationary and epistemic errors in both data and models, such tests could be carried out within a rejectionist limits-of-acceptability framework. The principles and difficulties of hypothesis testing within these particular research areas are discussed. An important point to take from this discussion is that the use of a formal testing framework, and the consequent rejection of models as hypotheses after allowing for uncertainties in the data, is the starting point for developing better theories and data sets. Copyright (C) 2010 John Wiley & Sons, Ltd.

  • 16.
    Beven, Keith
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    So how much of your error is epistemic? Lessons from Japan and Italy2013Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 27, nr 11, s. 1677-1680Artikel i tidskrift (Övrigt vetenskapligt)
  • 17.
    Beven, Keith
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Buytaert, Wouter
    Smith, Leonard A.
    On virtual observatories and modelled realities: (or why discharge must be treated as a virtual variable)2012Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 26, nr 12, s. 1905-1908Artikel i tidskrift (Refereegranskat)
  • 18.
    Beven, Keith
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära. Univ Lancaster, Lancaster Environm Ctr, Lancaster LA1 4YQ, England.;Univ Lausanne, IDYST, Lausanne, Switzerland..
    Davies, Jess
    Univ Lancaster, Lancaster Environm Ctr, Lancaster LA1 4YQ, England..
    Velocities, celerities and the basin of attraction in catchment response2015Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, nr 25, s. 5214-5226Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Catchment systems are interestingly nonlinear, but their dynamics are constrained from being unduly chaotic by mass and energy balance requirements. There have been no attempts in hydrology that we know of that have tried to map both the flow and transport dynamics of a catchment in any form of phase space. In part, this is because of the high dimensionality of the space-time patterns of response; in part because there is sufficient uncertainty about the input and output fluxes estimated by measurement that this might be expected to obscure any attractor-like behaviour. In this study we explore the basin of the catchment attractor for the Multiple Interacting Pathway (MIPs) model that in previous papers has been shown to give good results for the small Gardsjon catchment in Sweden. MIPs is based on particle tracking techniques and gives results for both the flow responses and for the travel and residence time responses of water in the catchment. Here it is used to provide consistent values of fluxes, total storage, travel time distributions and residence time distributions for a long simulation period. The nature of those responses in storage and input dimensions is then investigated. The results suggest that the range of behaviours is hysteretic in interesting ways and constrained by the forcing inputs, with space filling of trajectories in the basin of attraction as should be expected of a forced dissipative system. The range of behaviours exhibited defines a space that the responses of any simpler emulator model will need to span.

  • 19.
    Beven, Keith J.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Binley, Andrew
    GLUE: 20 years on2014Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, nr 24, s. 5897-5918Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    This paper reviews the use of the Generalized Likelihood Uncertainty Estimation (GLUE) methodology in the 20 years since the paper by Beven and Binley in Hydrological Processes in (1992), which is now one of the most highly cited papers in hydrology. The original conception, the on-going controversy it has generated, the nature of different sources of uncertainty and the meaning of the GLUE prediction uncertainty bounds are discussed. The hydrological, rather than statistical, arguments about the nature of model and data errors and uncertainties that are the basis for GLUE are emphasized. The application of the Institute of Hydrology distributed model to the Gwy catchment at Plynlimon presented in the original paper is revisited, using a larger sample of models, a wider range of likelihood evaluations and new visualization techniques. It is concluded that there are good reasons to reject this model for that data set. This is a positive result in a research environment in that it requires improved models or data to be made available. In practice, there may be ethical issues of using outputs from models for which there is evidence for model rejection in decision making. Finally, some suggestions for what is needed in the next 20 years are provided.

  • 20.
    Beven, Keith
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Westerberg, Ida
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    On red herrings and real herrings: disinformation and information in hydrological inference2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 10, s. 1676-1680Artikel i tidskrift (Övrigt vetenskapligt)
  • 21. Bishop, K.
    et al.
    Seibert, J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Nyberg, L.
    Rodhe, A.
    Water storage in a till catchment. II: Implications of transmissivity feedback for flow paths and turnover times2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 25, s. 3950-3959Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper explores the flow paths and turnover times within a catchment characterized by the transmissivity feedback mechanism where there is a strong increase in the saturated hydraulic conductivity towards the soil surface and precipitation inputs saturate progressively more superficial layers of the soil profile. The analysis is facilitated by the correlation between catchment water storage and groundwater levels, which made it possible to model the daily spatial distribution of water storage, both vertically in different soil horizons and horizontally across a 6300-m2 till catchment. Soil properties and episodic precipitation input dynamics, combined with the influence of topographic features, concentrate flow in the horizontal, vertical, and temporal dimensions. Within the soil profile, there was a vertical concentration of lateral flow to superficial soil horizons (upper 30?cm of the soil), where much of the annual flow occurred during runoff episodes. Overland flow from a limited portion of the catchment can contribute to peak flows but is not a necessary condition for runoff episodes. The spatial concentration of flow, and the episodic nature of runoff events, resulted in a strong and spatially structured differentiation of local flow velocities within the catchment. There were large differences in the time spent by the laterally flowing water at different depths, with turnover times of lateral flow across a 1-m-wide soil pedon ranging from under 1?h at 10- to 20-cm depth to a month at 70- to 80-cm depth. In many regards, the hydrology of this catchment appears typical of the hydrology in till soils, which are widespread in Fenno-Scandia. Copyright (c) 2011 John Wiley & Sons, Ltd.

  • 22.
    Bishop, Kevin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Uppsala centrum för hållbar utveckling, CSD Uppsala.
    Seibert, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    A primer for hydrology: the beguiling simplicity of Water's journey from rain to stream at 30 Preface2015Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, nr 16, s. 3443-3446Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Water's journey from rain to stream by Harald Grip and Allan Rodhe (1985, in Swedish: Vattnets vag fran regn till back) was one of the first textbooks to present groundwater contributions as a major feature of runoff generation, with implications for water quality and management. Three decades later, we have the privilege of presenting a special issue of Hydrological Processes, Runoff Generation in a Nordic Light: 30Years with Water's Journey from Rain to Stream' that seeks to introduce the book to a larger audience and continue the journey of ideas that the authors set in motion with their book.

  • 23.
    Bishop, Kevin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Seibert, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Nyberg, Lars
    Rodhe, Allan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Water storage in a till catchment. II: Implications of transmissivity feedback for flow paths and turnover times2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 25, s. 3950-3959Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper explores the flow paths and turnover times within a catchment characterized by the transmissivity feedback mechanism where there is a strong increase in the saturated hydraulic conductivity towards the soil surface and precipitation inputs saturate progressively more superficial layers of the soil profile. The analysis is facilitated by the correlation between catchment water storage and groundwater levels, which made it possible to model the daily spatial distribution of water storage, both vertically in different soil horizons and horizontally across a 6300-m2 till catchment. Soil properties and episodic precipitation input dynamics, combined with the influence of topographic features, concentrate flow in the horizontal, vertical, and temporal dimensions. Within the soil profile, there was a vertical concentration of lateral flow to superficial soil horizons (upper 30?cm of the soil), where much of the annual flow occurred during runoff episodes. Overland flow from a limited portion of the catchment can contribute to peak flows but is not a necessary condition for runoff episodes. The spatial concentration of flow, and the episodic nature of runoff events, resulted in a strong and spatially structured differentiation of local flow velocities within the catchment. There were large differences in the time spent by the laterally flowing water at different depths, with turnover times of lateral flow across a 1-m-wide soil pedon ranging from under 1?h at 10- to 20-cm depth to a month at 70- to 80-cm depth. In many regards, the hydrology of this catchment appears typical of the hydrology in till soils, which are widespread in Fenno-Scandia.

  • 24.
    Bishop, Kevin
    et al.
    Uppsala University.
    Seibert, Jan
    Uppsala University, Switzerland.
    Nyberg, Lars
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Centrum för klimat och säkerhet.
    Rodhe, Allan
    Uppsala University.
    Water storage in a till catchment: II: Implications of transmissivity feedback for flow paths and turnover times2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 25, s. 3950-3959Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper explores the flow paths and turnover times within a catchment characterized by the transmissivity feedback mechanism where there is a strong increase in the saturated hydraulic conductivity towards the soil surface and precipitation inputs saturate progressively more superficial layers of the soil profile. The analysis is facilitated by the correlation between catchment water storage and groundwater levels, which made it possible to model the daily spatial distribution of water storage, both vertically in different soil horizons and horizontally across a 6300-m2 till catchment. Soil properties and episodic precipitation input dynamics, combined with the influence of topographic features, concentrate flow in the horizontal, vertical, and temporal dimensions. Within the soil profile, there was a vertical concentration of lateral flow to superficial soil horizons (upper 30 cm of the soil), where much of the annual flow occurred during runoff episodes. Overland flow from a limited portion of the catchment can contribute to peak flows but is not a necessary condition for runoff episodes. The spatial concentration of flow, and the episodic nature of runoff events, resulted in a strong and spatially structured differentiation of local flow velocities within the catchment. There were large differences in the time spent by the laterally flowing water at different depths, with turnover times of lateral flow across a 1-m-wide soil pedon ranging from under 1 h at 10- to 20-cm depth to a month at 70- to 80-cm depth. In many regards, the hydrology of this catchment appears typical of the hydrology in till soils, which are widespread in Fenno-Scandia.

  • 25.
    Borris, Matthias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Gustafsson, Anna-Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Marsalek, Jiri
    National Water Research Institute, Environment Canada.
    Modelling the effects of changes in rainfall event characteristics on TSS loads in urban runoff2014Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, nr 4, s. 1787-1796Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of changes in rainfall event characteristics on urban stormwater quality, which was described by total suspended solids (TSS), was studied by means of computer simulations conducted with the Storm Water Management Model for a climate change scenario for northern Sweden. The simulation results showed that TSS event loads depended mainly on rainfall depth and intensity, but not on antecedent conditions. Storms with low-to-intermediate depths and intensities showed the highest sensitivity to changes in rainfall input, both for percentage and absolute changes in TSS wash-off loads, which was explained by the contribution of pervious areas and supply limitations. This has significant implications for stormwater management, because those relatively frequent events generally carry a high percentage of the annual pollutant load

  • 26. Carey, Sean K.
    et al.
    Tetzlaff, Doerthe
    Seibert, J.
    Department of Geography, University of Zurich, Zurich, Switzerland.
    Soulsby, Chris
    Buttle, Jim
    Laudon, Hjalmar
    McDonnell, Jeff
    McGuire, Kevin
    Caissie, Daniel
    Shanley, Jamie
    Kennedy, Mike
    Devito, Kevin
    Pomeroy, John W.
    Inter-comparison of hydro-climatic regimes across northern catchments: synchronicity, resistance and resilience2010Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, nr 24, s. 3591-3602Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The higher mid-latitudes of the Northern Hemisphere are particularly sensitive to climate change as small differences in temperature determine frozen ground status, precipitation phase, and the magnitude and timing of snow accumulation and melt. An international inter-catchment comparison program, North-Watch, seeks to improve our understanding of the sensitivity of northern catchments to climate change by examining their hydrological and biogeochemical responses. The catchments are located in Sweden (Krycklan), Scotland (Mharcaidh, Girnock and Strontian), the United States (Sleepers River, Hubbard Brook and HJ Andrews) and Canada (Catamaran, Dorset and Wolf Creek). This briefing presents the initial stage of the North-Watch program, which focuses on how these catchments collect, store and release water and identify 'types' of hydro-climatic catchment response. At most sites, a 10-year data of daily precipitation, discharge and temperature were compiled and evaporation and storage were calculated. Inter-annual and seasonal patterns of hydrological processes were assessed via normalized fluxes and standard flow metrics. At the annual-scale, relations between temperature, precipitation and discharge were compared, highlighting the role of seasonality, wetness and snow/frozen ground. The seasonal pattern and synchronicity of fluxes at the monthly scale provided insight into system memory and the role of storage. We identified types of catchments that rapidly translate precipitation into runoff and others that more readily store water for delayed release. Synchronicity and variance of rainfall-runoff patterns were characterized by the coefficient of variation (cv) of monthly fluxes and correlation coefficients. Principal component analysis (PCA) revealed clustering among like catchments in terms of functioning, largely controlled by two components that (i) reflect temperature and precipitation gradients and the correlation of monthly precipitation and discharge and (ii) the seasonality of precipitation and storage. By advancing the ecological concepts of resistance and resilience for catchment functioning, results provided a conceptual framework for understanding susceptibility to hydrological change across northern catchments. Copyright (C) 2010 John Wiley & Sons, Ltd.

  • 27. Carey, Sean K.
    et al.
    Tetzlaff, Doerthe
    Seibert, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Soulsby, Chris
    Buttle, Jim
    Laudon, Hjalmar
    McDonnell, Jeff
    McGuire, Kevin
    Caissie, Daniel
    Shanley, Jamie
    Kennedy, Mike
    Devito, Kevin
    Pomeroy, John W.
    Inter-comparison of hydro-climatic regimes across northern catchments: synchronicity, resistance and resilience2010Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, nr 24, s. 3591-3602Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The higher mid-latitudes of the Northern Hemisphere are particularly sensitive to climate change as small differences in temperature determine frozen ground status, precipitation phase, and the magnitude and timing of snow accumulation and melt. An international inter-catchment comparison program, North-Watch, seeks to improve our understanding of the sensitivity of northern catchments to climate change by examining their hydrological and biogeochemical responses. The catchments are located in Sweden (Krycklan), Scotland (Mharcaidh, Girnock and Strontian), the United States (Sleepers River, Hubbard Brook and HJ Andrews) and Canada (Catamaran, Dorset and Wolf Creek). This briefing presents the initial stage of the North-Watch program, which focuses on how these catchments collect, store and release water and identify 'types' of hydro-climatic catchment response. At most sites, a 10-year data of daily precipitation, discharge and temperature were compiled and evaporation and storage were calculated. Inter-annual and seasonal patterns of hydrological processes were assessed via normalized fluxes and standard flow metrics. At the annual-scale, relations between temperature, precipitation and discharge were compared, highlighting the role of seasonality, wetness and snow/frozen ground. The seasonal pattern and synchronicity of fluxes at the monthly scale provided insight into system memory and the role of storage. We identified types of catchments that rapidly translate precipitation into runoff and others that more readily store water for delayed release. Synchronicity and variance of rainfall-runoff patterns were characterized by the coefficient of variation (cv) of monthly fluxes and correlation coefficients. Principal component analysis (PCA) revealed clustering among like catchments in terms of functioning, largely controlled by two components that (i) reflect temperature and precipitation gradients and the correlation of monthly precipitation and discharge and (ii) the seasonality of precipitation and storage. By advancing the ecological concepts of resistance and resilience for catchment functioning, results provided a conceptual framework for understanding susceptibility to hydrological change across northern catchments.

  • 28. Chen, X.
    et al.
    Chen, Y.D.
    Xu, Chong-yu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft- och vattenlära.
    A distributed monthly hydrological model for integrating spatial variations of basin topography and rainfall2007Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 21, nr 2, s. 242-252Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrological models at a monthly time-scale are important tools for hydrological analysis, such as in impact assessment of climate change and regional water resources planning. Traditionally, monthly models adopt a conceptual, lumped-parameter approach and cannot account for spatial variations of basin characteristics and climatic inputs. A large requirement for data often severely limits the utility of physically based, distributed-parameter models. Based on the variable-source-area concept, we considered basin topography and rainfall to be two major factors whose spatial variations play a dominant role in runoff generation and developed a monthly model that is able to account for their influences in the spatial and temporal dynamics of water balance. As a hybrid of the Xinanjiang model and TOPMODEL, the new model is constructed by innovatively making use of the highly acclaimed simulation techniques in the two existing models. A major contribution of this model development study is to adopt the technique of implicit representation of soil moisture characteristics in the Xinanjiang model and use the TOPMODEL concept to integrate terrain variations into runoff simulation. Specifically, the TOPMODEL topographic index ln(a/tan) is converted into an index of relative difficulty in runoff generation (IRDG) and then the cumulative frequency distribution of IRDG is used to substitute the parabolic curve, which represents the spatial variation of soil storage capacity in the Xinanjiang model. Digital elevation model data play a key role in the modelling procedures on a geographical information system platform, including basin segmentation, estimation of rainfall for each sub-basin and computation of terrain characteristics. Other monthly data for model calibration and validation are rainfall, pan evaporation and runoff. The new model has only three parameters to be estimated, i.e. watershed-average field capacity WM, pan coefficient and runoff generation coefficient . Sensitivity analysis demonstrates that runoff is least sensitive to WM and, therefore, it can be determined by a prior estimation based on the climate and soil properties of the study basin. The other two parameters can be determined using optimization methods. Model testing was carried out in a number of nested sub-basins of two watersheds (Yuanjiang River and Dongjiang River) in the humid region in central and southern China. Simulation results show that the model is capable of describing spatial and temporal variations of water balance components, including soil moisture content, evapotranspiration and runoff, over the watershed. With a minimal requirement for input data and parameterization, this terrain-based distributed model is a valuable contribution to the ever-advancing technology of hydrological modelling.

  • 29. Chen, Xi
    et al.
    Cheng, Qinbo
    Chen, Yongqin David
    Smettem, Keith
    Xu, Chong-Yu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Simulating the integrated effects of topography and soil properties on runoff generation in hilly forested catchments, South China2010Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, nr 6, s. 714-725Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Estimation of runoff components associated with catchment topography and soil properties is critical for planning water resources utilization and evaluating hydrological changes due to artificially induced land surface manipulation. In this study, the modified TOPMODEL by Scanlon et al. (2000) was applied to simulate runoff-generating processes and to separate runoff components in two hilly forested catchments within the Dongjiang Basin of Southeast China. The modified TOPMODEL was improved by integrating an evapotranspiration package with the model algorithms. Influences of catchment topography and soil properties on runoff generation were analysed on the basis of explicit expression of catchment field capacity distribution derived from the topographic index and catchment average field capacity. Study results demonstrate that the model is capable of simulating hydrological processes and separate hydrological components in both hourly and daily time steps. Total runoff generation primarily depends on the effective storage capacity of unsaturated zone. A 50% decrease of the effective storage capacity from 0.22 to 0.11 m over the soil zone leads to a 6.6% increase in total runoff. Topography plays a dominant role in formation of runoff components. When the catchment mean slope increases by 87%, subsurface storm flow could increase by 50% whilst overland flow decreases by 7.5% and baseflow by 6.7%. Vertical changes of soil permeability influence runoff components as well. Decrease of the lower layer hydraulic transmissivity may result in 2-3% increase of overland flow and subsurface storm flow and 5% decrease of baseflow.

  • 30. Dahlke, Helen E.
    et al.
    Behrens, Thorsten
    Seibert, Jan
    Andersson, Lotta
    SMHI, Samhälle och säkerhet.
    Test of statistical means for the extrapolation of soil depth point information using overlays of spatial environmental data and bootstrapping techniques2009Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 23, nr 21, s. 3017-3029Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrological modelling depends highly on the accuracy and uncertainty of model input parameters such as soil properties. Since most of these data are field Surveyed, geostatistical techniques Such as kriging, classification and regression trees or more sophisticated soil-landscape models need to be applied to interpolate point information to the area. Most of the existing interpolation techniques require a random or regular distribution of points Within the study area but are not adequate to satisfactorily interpolate soil catena or transect data. The soil landscape model presented in this study is predicting soil information from transect or catena point data using a statistical mean (arithmetic, geometric and harmonic mean) to calculate the soil information based on class means of merged spatial explanatory variables. A data set of 226 soil depth measurements covering a range of 0-6.5 m was used to test the model. The point data were sampled along four transects in the Stubbetorp catchment, SE-Sweden. We overlaid a geomorphology map (8 classes) with digital elevation model-derived topographic index maps (2-9 classes) to estimate the range of error the model produces with changing sample size and input maps. The accuracy of the soil depth predictions was estimated with the root mean square error (RMSE) based oil a testing and training data set. RMSE ranged generally between 0.73 and 0.83 m +/- 0.013 m depending on the amount of classes the merged layers had, but were smallest for a map combination with a low number of classes predicted with the harmonic mean (RMSE = 0.46 m). The results show that the prediction accuracy of this method depends oil the number of point values in the sample, the value range of the measured attribute and the initial correlations between point values and explanatory variables, but suggests that the model approach is in general scale invariant. Copyright (C) 2009 John Wiley & Sons, Ltd.

  • 31.
    Dahlke, Helen E.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Lyon, Steve W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Jansson, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Karlin, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Rosqvist, Gunhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Isotopic investigation of runoff generation in a glacierized catchment in northern Sweden2014Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, nr 3, s. 1383-1398Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, summer rainfall contributions to streamflow were quantified in the sub-arctic, 30% glacierized Tarfala (21.7km(2)) catchment in northern Sweden for two non-consecutive summer sampling seasons (2004 and 2011). We used two-component hydrograph separation along with isotope ratios (O-18 and D) of rainwater and daily streamwater samplings to estimate relative fraction and uncertainties (because of laboratory instrumentation, temporal variability and spatial gradients) of source water contributions. We hypothesized that the glacier influence on how rainfall becomes runoff is temporally variable and largely dependent on a combination of the timing of decreasing snow cover on glaciers and the relative moisture storage condition within the catchment. The results indicate that the majority of storm runoff was dominated by pre-event water. However, the average event water contribution during storm events differed slightly between both years with 11% reached in 2004 and 22% in 2011. Event water contributions to runoff generally increased over 2011 the sampling season in both the main stream of Tarfala catchment and in the two pro-glacial streams that drain Storglaciaren (the largest glacier in Tarfala catchment covering 2.9km(2)). We credit both the inter-annual and intra-annual differences in event water contributions to large rainfall events late in the summer melt season, low glacier snow cover and elevated soil moisture due to large antecedent precipitation. Together amplification of these two mechanisms under a warming climate might influence the timing and magnitude of floods, the sediment budget and nutrient cycling in glacierized catchments.

  • 32. Dahlke, Helen E.
    et al.
    Williamson, Andrew G.
    Georgakakos, Christine
    Leung, Selene
    Sharma, Asha N.
    Lyon, Steve W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Walter, M. Todd
    Using concurrent DNA tracer injections to infer glacial flow pathways2015Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, nr 25, s. 5257-5274Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Catchment hydrology has become replete with flow pathway characterizations obtained via combinations of physical hydrologic measurements (e.g. streamflow hydrographs) and natural tracer signals (e.g. stable water isotopes and geochemistry). In this study, we explored how our understanding of hydrologic flow pathways can be improved and expanded in both space and time by the simultaneous application of engineered synthetic DNA tracers. In this study, we compared the advective-dispersive transport properties and mass recovery rates of two types of synthetic DNA tracers, one consisting of synthetic DNA strands encapsulated into biodegradable microspheres and another consisting of `free' DNA, i.e. not encapsulated. The DNA tracers were also compared with a conservative fluorescent dye. All tracers were injected into a small (3.2-km(2)) valley glacier, Storglaciaren, in northern Sweden. Seven of the nine DNA tracers showed clear recovery during the sampling period and similar peak arrival times and dispersion coefficients as the conservative fluorescent dye. However, recovered DNA tracer mass ranged only from 1% to 66%, while recovered fluorescent dye mass was 99%. Resulting from the cold and opaque subglacial environment provided by the glacier, mass loss associated with microbial activity and photochemical degradation of the DNA is likely negligible, leaving sorption of DNA tracers onto suspended particles and loss of microtracer particles to sediment storage as probable explanations. Despite the difference in mass recovery, the advection and dispersion information derived from the DNA tracer breakthrough curves provided spatially explicit information that allowed inferring a theoretical model of the flow pathways that water takes through the glacier.

  • 33.
    Darracq, Amelie
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Persson, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Prieto, Carmen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Jarsjö, Jerker
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Scale and model resolution effects on the distributions of advective solute travel times in catchments2010Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, nr 12, s. 1697-1710Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Advective solute travel times and their distributions in hydrological catchments are useful descriptors of the dynamics and variation of the physical mass transport among and along the different source-to-recipient pathways of solute transport through the catchments. This article investigates the scale dependence and the effects of model and data resolution on the quantification of advective travel times and their distributions in the Swedish catchment areas of Norrström and Forsmark. In the surface water networks of the investigated (sub)catchments, the mean advective travel time increases with (sub)catchment scale, whereas the relative travel time variability around the mean value (coefficient of variation, CV) is scale-invariant and insensitive to model resolution. In the groundwater and for the whole (sub)catchments, both the mean value and the CV of travel times are scale-invariant, but sensitive to model resolution and accuracy. Such quantifications and results of advective travel times constitute important steps in the development of improved understanding and modelling of nutrient, pollutant and tracer transport through catchments.

  • 34. Davies, Jessica A. C.
    et al.
    Beven, Keith
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Hysteresis and scale in catchment storage, flow and transport2015Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, nr 16, s. 3604-3615Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The closure problem of representing hydrological boundary fluxes given the state of the system has been described as the scientific Holy Grail' of hydrology. This relationship between storage state and flux should be hysteretic and scale dependent because of the differences between velocities and celerities in a hydrological systemeffectively velocities are storage controlled, and celerities are controlled by storage deficits. To improve our understanding of the nature of these relationships a new hydrology model is used (the Multiple Interacting Pathways or MIPs model) to explore the influence of catchment scale on storage-flow-transport relationships, and their non-linearities. The MIPs model has been shown to produce acceptable simulations of both flow and tracer, i.e. of both celerities and velocities, at the Gardsjon catchment in Sweden. In this study the model is used to simulate scaled versions of the Gardsjon catchment to allow us for the first time to investigate the influence of scale on the non-linearities in storage-flow-transport relationships, and help us steer the quest for the scientific hydrological Holy Grail'. The simulations reveal the influence of scale on flow response in the nature of storage-discharge hysteresis and its links with antecedent storage; fractal-like systematic change of mean output travel times with scale; the effect of scale on input, output and storage residence time distributions; hysteric relations between storage and output travel times and links between storage and water table level hysteresis. (c) 2015 The Authors. Hydrological Processes published by John Wiley & Sons Ltd.

  • 35. Davies, Jessica
    et al.
    Beven, Keith J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Nyberg, Lars
    Rodhe, Allan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    A discrete particle representation of hillslope hydrology: hypothesis testing in reproducing a tracer experiment at Gardsjon, Sweden2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 23, s. 3602-3612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the long history of the continuum equation approach in hydrology, it is not a necessary approach to the formulation of a physically based representation of hillslope hydrology. The Multiple Interacting Pathways ( MIPs) model is a discrete realization that allows hillslope response and transport to be simultaneously explored in a way that reflects the potential occurrence of preferential flows and lengths of pathways. The MIPs model uses random particle tracking methods to represent the flow of water within the subsurface alongside velocity distributions that acknowledge preferential flows and transition probability matrices, which control flow pathways. An initial realization of this model is presented here in application to a tracer experiment carried out in Gardsjon, Sweden. The model is used as an exploratory tool, testing several hypotheses in relation to this experiment.

  • 36.
    Davies, Jessica
    et al.
    Lancaster University.
    Beven, Keith
    Lancaster University.
    Nyberg, Lars
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Centrum för klimat och säkerhet.
    Rodhe, Allan
    Uppsala universitet.
    A discrete particle representation of hillslope hydrology: hypothesis testing in reproducing a tracer experiment at Gårdsjön, Sweden2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 23, s. 3602-3612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the long history of the continuum equation approach in hydrology, it is not a necessary approach to the formulation of a physically based representation of hillslope hydrology. The Multiple Interacting Pathways (MIPs) model is a discrete realization that allows hillslope response and transport to be simultaneously explored in a way that reflects the potential occurrence of preferential flows and lengths of pathways. The MIPs model uses random particle tracking methods to represent the flow of water within the subsurface alongside velocity distributions that acknowledge preferential flows and transition probability matrices, which control flow pathways. An initial realization of this model is presented here in application to a tracer experiment carried out in Gårdsjön, Sweden. The model is used as an exploratory tool, testing several hypotheses in relation to this experiment.

  • 37. de Woul, Mattias
    et al.
    Hock, Regine
    Department of Physical Geography and Quaternary Geology, Stockholm University, Stockholm, Sweden.
    Braun, Matthias
    Thorsteinsson, Thorsteinn
    Jóhannesson, Tomas
    Firn layer impact on glacial runoff: a case study at Hofsjökull, Iceland2006Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 20, nr 10, s. 2171-2185Artikel i tidskrift (Refereegranskat)
  • 38.
    Di Baldassarre, Giuliano
    et al.
    School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, U.
    SCHUMANN, G
    BATES, P
    Near real time satellite imagery to support and verify timely flood modelling2009Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 23, nr 5, s. 799-803Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The study investigates the capability of coarse resolution synthetic aperture radar (SAR) imagery to support flood inundation models. A hydraulic model of a 98-km reach of the River Po (Northern Italy) was calibrated on the October 2000 high-magnitude flood event with extensive and high-quality field data. During the June 2008, low-magnitude flood event a SAR image was acquired and processed in near real time (NRT) in order to provide adequate data for quick verification and recalibration of the hydraulic model.

  • 39.
    Divine, D. V.
    et al.
    Univ Tromso, Dept Math & Stat, Tromso, Norway.;Polar Environm Ctr, Norwegian Polar Inst, Tromso, Norway..
    Sjolte, J.
    Univ Copenhagen, Niels Bohr Inst, Ctr Ice & Climate, DK-1168 Copenhagen, Denmark..
    Isaksson, E.
    Polar Environm Ctr, Norwegian Polar Inst, Tromso, Norway..
    Meijer, H. A. J.
    Univ Groningen, Ctr Isotope Res, Groningen, Netherlands..
    van de Wal, R. S. W.
    Univ Utrecht, Inst Marine & Atmospher Res Utrecht, NL-3508 TC Utrecht, Netherlands..
    Martma, T.
    Tallinn Univ Technol, Inst Geol, Tallinn, Estonia..
    Pohjola, V.
    Uppsala Univ, Dept Earth Sci, Uppsala, Sweden..
    Sturm, C.
    Stockholm Univ, Dept Geol & Geochem, S-10691 Stockholm, Sweden..
    Godtliebsen, F.
    Univ Tromso, Dept Math & Stat, Tromso, Norway..
    Modelling the regional climate and isotopic composition of Svalbard precipitation using REMOiso: a comparison with available GNIP and ice core data2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 24, s. 3748-3759Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simulations of a regional (approx. 50 km resolution) circulation model REMOiso with embedded stable water isotope module covering the period 1958-2001 are compared with the two instrumental climate and four isotope series (d18O) from western Svalbard. We examine the data from ice cores drilled on Svalbard ice caps in 1997 (Lomonosovfonna, 1250 m asl) and 2005 (Holtedahlfonna, 1150 m asl) and the GNIP series from Ny-angstrom lesund and Isfjord Radio. The surface air temperature (SAT) and precipitation data from Longyearbyen and Ny-angstrom lesund are used to assess the skill of the model in reproducing the local climate. The model successfully captures the climate variations on the daily to multidecadal times scales although it tends to systematically underestimate the winter SAT. Analysis suggests that REMOiso performs better at simulating isotope compositions of precipitation in the winter than summer. The simulated and measured Holtedahlfonna d18O series agree reasonably well, whereas no significant correlation has been observed between the modelled and measured Lomonosovfonna ice core isotopic series. It is shown that sporadic nature as well as variability in the amount inherent in precipitation process potentially limits the accuracy of the past SAT reconstruction from the ice core data. This effect in the study area is, however, diminished by the role of other factors controlling d18O in precipitation, most likely sea ice extent, which is directly related with the SAT anomalies. Copyright (C) 2011 John Wiley & Sons, Ltd.

  • 40. Divine, D. V.
    et al.
    Sjolte, J.
    Isaksson, E.
    Meijer, H. A. J.
    van de Wal, R. S. W.
    Martma, T.
    Pohjola, V.
    Sturm, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Godtliebsen, F.
    Modelling the regional climate and isotopic composition of Svalbard precipitation using REMOiso: a comparison with available GNIP and ice core data2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 24, s. 3748-3759Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simulations of a regional (approx. 50 km resolution) circulation model REMOiso with embedded stable water isotope module covering the period 1958-2001 are compared with the two instrumental climate and four isotope series (d18O) from western Svalbard. We examine the data from ice cores drilled on Svalbard ice caps in 1997 (Lomonosovfonna, 1250 m asl) and 2005 (Holtedahlfonna, 1150 m asl) and the GNIP series from Ny-angstrom lesund and Isfjord Radio. The surface air temperature (SAT) and precipitation data from Longyearbyen and Ny-angstrom lesund are used to assess the skill of the model in reproducing the local climate. The model successfully captures the climate variations on the daily to multidecadal times scales although it tends to systematically underestimate the winter SAT. Analysis suggests that REMOiso performs better at simulating isotope compositions of precipitation in the winter than summer. The simulated and measured Holtedahlfonna d18O series agree reasonably well, whereas no significant correlation has been observed between the modelled and measured Lomonosovfonna ice core isotopic series. It is shown that sporadic nature as well as variability in the amount inherent in precipitation process potentially limits the accuracy of the past SAT reconstruction from the ice core data. This effect in the study area is, however, diminished by the role of other factors controlling d18O in precipitation, most likely sea ice extent, which is directly related with the SAT anomalies.

  • 41.
    Divine, Dmitri V.
    et al.
    Tromsö universitet.
    Sjolte, J
    Isaksson, E
    Meijer, H. A. J.
    van de Wal, R. S. W.
    Martma, T
    Pohjola, Veijo A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Sturm, C
    Godtliebsen, F
    Modeling the regional climate and isotopic composition of Svalbard precipitation using REMOiso model: a comparison with available GNIP and ice core data2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 24, s. 3748-3759Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simulations of a regional (approx. 50 km resolution) circulation model REMOiso with embedded stable water isotope module covering the period 1958-2001 are compared with the two instrumental climate and four isotope series (d18O) from western Svalbard. We examine the data from ice cores drilled on Svalbard ice caps in 1997 (Lomonosovfonna, 1250 m asl) and 2005 (Holtedahlfonna, 1150 m asl) and the GNIP series from Ny-angstrom lesund and Isfjord Radio. The surface air temperature (SAT) and precipitation data from Longyearbyen and Ny-angstrom lesund are used to assess the skill of the model in reproducing the local climate. The model successfully captures the climate variations on the daily to multidecadal times scales although it tends to systematically underestimate the winter SAT. Analysis suggests that REMOiso performs better at simulating isotope compositions of precipitation in the winter than summer. The simulated and measured Holtedahlfonna d18O series agree reasonably well, whereas no significant correlation has been observed between the modelled and measured Lomonosovfonna ice core isotopic series. It is shown that sporadic nature as well as variability in the amount inherent in precipitation process potentially limits the accuracy of the past SAT reconstruction from the ice core data. This effect in the study area is, however, diminished by the role of other factors controlling d18O in precipitation, most likely sea ice extent, which is directly related with the SAT anomalies.

  • 42.
    Fabian, Mark
    et al.
    SUNY Coll Environm Sci & Forestry, Dept Environm Resources Engn, Baker Labs 423, Syracuse, NY 13210 USA.
    Endreny, Theodore
    SUNY Coll Environm Sci & Forestry, Dept Environm Resources Engn, Baker Labs 423, Syracuse, NY 13210 USA.
    Bottacin-Busolin, Andrea
    Water & Environm Technol Engn Srl, I-31033 Treviso, Italy.
    Lautz, Laura
    Syracuse Univ, Dept Earth Sci, Heroy Geol Lab 204, Syracuse, NY 13244 USA.
    Seasonal variation in cascade-driven hyporheic exchange, northern Honduras2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 10, s. 1630-1646Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A characterization of hyporheic exchange for dry and wet season baseflow, as well as partially dewatered discharge, was done in Prieta Creek, a first-order cascade in northern Honduras. The cascade had discharges from 1 to 15 1 s(-1), had average slopes of 12%, pool spacing of 3 m, and shallow substrate of sand and gravel. Tracer tests were conducted in a 15-m sub-reach, a length considered to be adequate for the experiment based on the DaI test, a ratio of exchange and transport processes. In the three tests, between 9 and 18% of tracer was not recovered, possibly due to entrainment in flowpaths passing beneath the downstream monitoring location. Tracer data were analysed by the one-dimensional transport with inflow and storage (OTIS) transient storage model (TSM) to derive standard exchange parameters, and by the solute transport in rivers (STIR) model to examine hyporheic residence time distributions (RTDs). The best fit of the observed tracer breakthrough curves was obtained by using the STIR model with a combination of two exponential RTDs to represent hyporheic retention. With increasing discharge, the OTIS model predicted increasing storage exchange fluxes and exchange coefficients and decreasing storage zone areas and transient storage times, which are trends supported by riparian and streambed piezometric head data. Riparian water levels rose during the transition from the dry to wet season, which could constrict the hyporheic storage zone. Thirteen of the 19 streambed piezometers recorded seasonal changes in hydraulic gradients and flux direction, with fewer yet stronger upwelling zones during higher discharges. The MODFLOW model missed the observed seasonal changes, possibly due to subtle changes in the seasonal change in water surface profiles. We conclude that partially dewatered dry season exchange, compared to wet season exchange, was initiated and terminated with smaller pressure gradients and, in different streambed locations, was smaller in volume, had longer residence times, and may connect with deeper and longer flow paths.

  • 43.
    Fischer, Benjamin M. C.
    et al.
    Univ Zurich, Dept Geog, CH-8057 Zurich, Switzerland..
    Rinderer, Michael
    Univ Zurich, Dept Geog, CH-8057 Zurich, Switzerland..
    Schneider, Philipp
    Univ Zurich, Dept Geog, CH-8057 Zurich, Switzerland..
    Ewen, Tracy
    Univ Zurich, Dept Geog, CH-8057 Zurich, Switzerland..
    Seibert, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära. Univ Zurich, Dept Geog, CH-8057 Zurich, Switzerland..
    Contributing sources to baseflow in pre-alpine headwaters using spatial snapshot sampling2015Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, nr 26, s. 5321-5336Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mountainous headwaters consist of different landscape units including forests, meadows and wetlands. In these headwaters it is unclear which landscape units contribute what percentage to baseflow. In this study, we analysed spatiotemporal differences in baseflow isotope and hydrochemistry to identify catchment-scale runoff contribution. Three baseflow snapshot sampling campaigns were performed in the Swiss pre-alpine headwater catchment of the Zckentobel (4.25 km(2)) and six of its adjacent subcatchments. The spatial and temporal variability of delta H-2, Ca, DOC, AT, pH, SO4, Mg and H4SiO4 of streamflow, groundwater and spring water samples was analysed and related to catchment area and wetland percentage using bivariate and multivariate methods. Our study found that in the six subcatchments, with variable arrangements of landscape units, the inter-and intra catchment variability of isotopic and hydrochemical compositions was small and generally not significant. Stream samples were distinctly different from shallow groundwater. An upper spring zone located near the water divide above 1,400m and a larger wetland were identified by their distinct spatial isotopic and hydrochemical composition. The upstream wetland percentage was not correlated to the hydrochemical streamflow composition, suggesting that wetlands were less connected and act as passive features with a negligible contribution to baseflow runoff. The isotopic and hydrochemical composition of baseflow changed slightly from the upper spring zone towards the subcatchment outlets and corresponded to the signature of deep groundwater. Our results confirm the need and benefits of spatially distributed snapshot sampling to derive process understanding of heterogeneous headwaters during baseflow.

  • 44. Floriancic, Marius G.
    et al.
    Fischer, Benjamin M. C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Molnar, Peter
    Kirchner, James W.
    van Meerveld, Ilja H. J.
    Spatial variability in specific discharge and streamwater chemistry during low flows: Results from snapshot sampling campaigns in eleven Swiss catchments2019Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 33, nr 22, s. 2847-2866Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Catchments consist of distinct landforms that affect the storage and release of subsurface water. Certain landforms may be the main contributors to streamflow during extended dry periods, and these may vary for different catchments in a given region. We present a unique dataset from snapshot field campaigns during low-flow conditions in 11 catchments across Switzerland to illustrate this. The catchments differed in size (10 to 110 km(2)), varied from predominantly agricultural lowlands to Alpine areas, and covered a range of physical characteristics. During each snapshot campaign, we jointly measured streamflow and collected water samples for the analysis of major ions and stable water isotopes. For every sampling location (basin), we determined several landscape characteristics from national geo-datasets, including drainage area, elevation, slope, flowpath length, dominant land use, and geological and geomorphological characteristics, such as the lithology and fraction of quaternary deposits. The results demonstrate very large spatial variability in specific low-flow discharge and water chemistry: Neighboring sampling locations could differ significantly in their specific discharge, isotopic composition, and ion concentrations, indicating that different sources contribute to streamflow during extended dry periods. However, none of the landscape characteristics that we analysed could explain the spatial variability in specific discharge or streamwater chemistry in multiple catchments. This suggests that local features determine the spatial differences in discharge and water chemistry during low-flow conditions and that this variability cannot be assessed a priori from available geodata and statistical relations to landscape characteristics. The results furthermore suggest that measurements at the catchment outlet during low-flow conditions do not reflect the heterogeneity of the different source areas in the catchment that contribute to streamflow.

  • 45.
    Friberg, Nikolai
    et al.
    Department of Bioscience, Aarhus University, Silkeborg, Denmark.
    Bergfur, Jenny
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Rasmussen, Jes
    Department of Bioscience, Aarhus University, Silkeborg, Denmark.
    Sandin, Leonard
    Changing Northern catchments: Is altered hydrology, temperature or both going to shape future stream communities and ecosystem processes?2013Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 27, nr 5, s. 734-740Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Global change is predicted to increase temperature substantially in the North as well as altering run-off regimes with less synchronicity as the importance of snow melt declines. River biota and ecosystem processes will be influenced across all levels of organization, both in concert and individually. It is of vital importance that the impacts, and their likely magnitude, can be identified in order to deploy suitable adaptation strategies at the catchment scale. In this paper, we re-analyse four data sets from studies conducted in Greenland (66–69oN), Iceland (64oN), Sweden (60oN) and Denmark (55–57oN) to try and tease out the likely impacts of water temperature and hydrology in shaping the stream communities and ecosystem processes in high-latitude catchments. Water temperature was the environmental variable that best explained macroinvertebrate community composition across latitudes. In contrast, no significant relationship between macroinvertebrate community composition and measures of hydraulic stability (or nutrients) was found. We found a strong linear relationship between decay rate of leaf litter and water temperature (r2 = 0.68; p < 0.0001) independent of latitudes. Our study suggests that temperature could be the primary driver of ecosystem change in future with northern catchments likely to be especially vulnerable.

  • 46. Garg, Kaushal K.
    et al.
    Wani, Suhas P.
    Barron, Jennie
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre. University of York, United Kingdom.
    Karlberg, Louise
    Stockholms universitet, Stockholm Environment Institute. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Rockström, Johan
    Stockholms universitet, Stockholm Environment Institute. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Reply to comment on ‘Up-scaling potential impacts on water flows from agricultural water interventions: opportunities and trade‐offs in the Osman Sagar catchment, Musi sub‐basin, India’. Hydrological Processes 27: 3905–3921 by Bouma et al., 20142014Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, nr 8, s. 3352-3355Artikel i tidskrift (Övrigt vetenskapligt)
  • 47. Garg, Kaushal K.
    et al.
    Wani, Suhas P.
    Barron, Jennie
    Stockholms universitet, Stockholm Resilience Centre, Stockholm Environment Institute.
    Karlberg, Louise
    Stockholms universitet, Stockholm Resilience Centre, Stockholm Environment Institute.
    Rockström, Johan
    Stockholms universitet, Stockholm Resilience Centre, Stockholm Environment Institute.
    Up-scaling potential impacts on water flows from agricultural water interventions: opportunities and trade-offs in the Osman Sagar catchment, Musi sub-basin, India2013Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 27, nr 26, s. 3905-3921Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Agricultural water management (AWM) has been shown to improve and secure yields in the tropics and has been suggested as an important way to combat poverty in the region. In this paper, we describe potential impacts on upstream and downstream flows of extensive AWM interventions, using the watershed development programme of the Osman Sagar catchment of Musi sub-basin, Andhra Pradesh semi-arid India, as an example. Various AWM interventions are compared with a non-intervention state and the current state of the study area, using 31 years of data by application of the calibrated and validated ARCSWAT 2005 (Version 2.1.4a) modelling tool. Different AWM interventions contribute to improved livelihoods of upstream smallholder farmers by increasing soil moisture availability and groundwater recharge, which can subsequently be used for irrigation. The result is higher crop production and hence larger incomes. Moreover, lower flow intensities and sediment losses reduced by 30-50%, reducing the risk of flooding and sediment accumulation in the Osman Sagar drinking water reservoir. On the other hand, AWM interventions are predicted to result in reduced total water inflows to the Osman Sagar reservoir from 11% of the total annual rainfall (754mm) recorded at present, to 8% if AWM interventions were implemented at large scale throughout the catchment. A cost-benefit analysis of AWM interventions showed that the highest net economic returns were achieved at intermediate intervention levels (only in-situ AWM).

  • 48. Garg, K.K.
    et al.
    Karlberg, Louise
    Stockholms universitet, Stockholm Resilience Centre, Stockholm Environment Institute.
    Barron, Jennie
    Stockholm Environment Institute, York, UK.
    Wani, S.P.
    Rockström, Johan
    Stockholms universitet, Stockholm Resilience Centre, Stockholm Environment Institute.
    Assessing impacts of agricultural water interventions in the Kothapally watershed, Southern India2012Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 26, nr 3, s. 387-404Artikel i tidskrift (Refereegranskat)
  • 49.
    Gong, Lebing
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Halldin, Sven
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Xu, Chong-Yu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Global-scale river routing-an efficient time-delay algorithm based on HydroSHEDS high-resolution hydrography2011Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 7, s. 1114-1128Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coupling of global hydrologic and atmospheric models is difficult because of the highly nonlinear hydrological processes to be integrated at large scales. Aggregation of high-resolution data into low-resolution spatial distribution functions is one way to preserve information and account for the nonlinearity. We used HydroSHEDS, presently the most highly resolved (3 '') global hydrography available, to provide accurate control on global river routing through a computationally efficient algorithm. The high resolution of HydroSHEDS allowed discrimination of river-channel pixels, and time-delay distributions were calculated for all such pixels. The distributions were aggregated into network-response functions (NRFs) for each low-resolution cell using an algorithm originally developed for the 1-km-resolution HYDRO1k hydrography. The large size of HydroSHEDS required a modification in algorithm to maintain computational efficiency. The new algorithm was tested with a high-quality local and a more uncertain global weather dataset to identify whether improved routing would provide a gain when weather data quality was limiting. The routing was coupled to the WASMOD-M runoff-generation model to evaluate discharge from the Dongjiang River and the Willamette River basins. The HydroSHEDS-based routing, compared with the HYDRO1k-based routing, provided a small gain in model efficiency, for local and global weather data and for both test basins. The HydroSHEDS-based routing, contrary to the HYDRO1k-based routing, provided physically realistic wave velocities. The most stable runoff-generation parameter values were achieved when HydroSHEDS was used to derive the NRFs. Routing was computed in two steps: first, a preparatory calculation which was a one-time effort and second, the routing during each simulation. The computational efficiency was four to five orders of magnitude better for the simulation step than that for the preparatory step.

  • 50. Granlund, Nils
    et al.
    Lundberg, Angela
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Gustafson, David
    KTH Royal Institute of Technology, Land and Water Resources Engineering.
    Laboratory study of the influence of salinity on the relationship between electrical conductivity and wetness of snow2010Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, nr 14, s. 1981-1984Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Snow water equivalent of a snowpack can be estimated using ground-penetrating radar from the radar wave two-way travel time. However, such estimates often have low accuracy when the snowpack contains liquid water. If snow wetness is known, it is possible to take it into account in the estimates; it is therefore desirable to be able to determine snow wetness from already available radar data. Our approach is based on using radar wave attenuation, and it requires that the relationship between electrical conductivity and wetness of snow should be known. This relationship has been tentatively established in previous laboratory experiments, but only for a specific liquid water salinity and radar frequency. This article presents the results of new laboratory experiments conducted to investigate if and how this relationship is influenced by salinity. In each experiment, a certain amount of snow was melted and a known amount of salt (different for different experiments) was added to the water. Water salinity was measured, and the water was added step-wise to a one-meter thick snowpack, with radar measurements taken between additions of water. Our experiments have confirmed the earlier established linear relationship between electrical conductivity and wetness of snow, and they allow us to suggest that the influence of liquid water salinity on electrical conductivity is negligible when compared to the influence of liquid water content in snow

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