Water management in Sweden is focused on characterization of water bodies and establishing action... more Water management in Sweden is focused on characterization of water bodies and establishing action plans to achieve a good ecological status according to the framework directives stated by the European Union. To support this work SMHI has been commissioned to make databases of hydrography, statistics, water flows and scenario models freely available on the web. As a result of this we have created the open website vattenweb.smhi.se. The site currently provides observed and modeled data for fresh water and coastal areas as time series and statistics. In addition to this, the site also exposes data on wetlands and results from climate scenario simulations. The development of the site has been done in close cooperation with the end users at the water authorities to meet their needs and requirements. This has resulted in an easy to use website, where downloaded data easily can be imported into other tools for further use and analysis by the users. However, during the process we discovered...
Flow Pathways on Steep Forested Hillslopes: the Tracer, Tensiometer and Trough Approach Jeffrey M... more Flow Pathways on Steep Forested Hillslopes: the Tracer, Tensiometer and Trough Approach Jeffrey MCDONNELL* 1, Dean BRAMMER* 1, Carol KENDALL* 2, Niclas HJERDT* 1, Lindsay ROWE*\ Mike STEWART* 4 and Ross WOODS* 5 * 1 SUNY-ESF. 1 Forestry Drive. ...
Abstract Log floating in the 19th to mid 20th centuries has profoundly changed the environmental ... more Abstract Log floating in the 19th to mid 20th centuries has profoundly changed the environmental conditions in many northern river systems of the world. Regulation of flow by dams, straightening and narrowing of channels by various piers and wing dams, and homogenization of bed structure are some of the major impacts. As a result, the conditions for many riverine organisms have been altered. Removing physical constructions and returning boulders to the channels can potentially restore conditions for these organisms. ...
ABSTRACT In a steep, forested headwater catchment at Sleepers River, Vermont, research during the... more ABSTRACT In a steep, forested headwater catchment at Sleepers River, Vermont, research during the 1990s identified two discreet groundwater regimes: (1) a riparian zone, in which discharging groundwater creates a well-mixed aquifer with chemistry stoichiometrically similar to streamwater, and (2) a hillslope zone, with chemistry that varies widely but is generally quite different from streamwater. In contrast to the damped changes in riparian groundwater levels, the water table in hillslope positions increased a meter or more during large events, peaking after the streamflow peak. Despite the strong hydrologic dynamics in the hillslope, the chemistry of hillslope water, most notably its high Si concentration, was not detected in streamwater. More recent study has revealed a continuum of subsurface environments, with groundwater chemistry approaching streamwater stoichiometry along convergent flow paths. However, the fate of the high Si concentrations in hillslope groundwater has not been satisfactorily explained. Whereas past studies assumed conservative mixing of source waters, the aim of this presentation is to synthesize and reinterpret these past studies by giving greater consideration to potential biogeochemical reactions through the use of equilibrium modeling
ABSTRACT Few measures exist for objectively comparing the chemistry of streams. We develop a mult... more ABSTRACT Few measures exist for objectively comparing the chemistry of streams. We develop a multivariate technique, based on an eigenvalue analysis of streamwater concentrations, to facilitate comparison of water quality among sites across basin scales. A correlation matrix is constructed to include only solutes that mix conservatively. An eigenvalue analysis of this matrix is performed at each site to determine the approximate rank of the data set. If the ranks of all sites are roughly equal, one site is chosen as the reference site. The reduced set of eigenvectors from this site is chosen as the basis for a new, lower dimensional coordinate system and the data from the other sites are projected into this coordinate system. To assess the relative orientation of data from the reference site to all of the other sites, the relative bias (RB) and relative root mean square error (RRMSE) are calculated between the original and the projected points. The new technique was applied to multiple sites within three experimental watersheds to assess the consistency of water quality across the basin scale. The three watersheds were: Panola Mountain, Georgia, USA (6 solutes, 8 sites, 3 to 1000 ha); Sleepers River, Vermont, USA (5 solutes, 7 sites, 3 to 840 ha); and Maimai, South Island, New Zealand (4 solutes, 4 sites, 3 to 300 ha). Data from all sites were roughly planar with the first two eigenvectors explaining more than 90% of the variation. The RRMSEs for the reference site were generally between 5 and 10% with
ABSTRACT It is often assumed that hillslope and riparian areas constitute the two most important ... more ABSTRACT It is often assumed that hillslope and riparian areas constitute the two most important and identifiable landscape units contributing to catchment runoff in upland humid catchments. Nevertheless, the relative amount and timing of hillslope versus riparian contributions to stormflow are poorly understood across different watersheds. We quantified the contributions of hillslopes and riparian zones to stormflow using physical, chemical, and isotopic techniques across 3 diverse ({ ~}15 ha) headwater catchments: a highly responsive steep wet watershed (Maimai, New Zealand), a moderately steep snowmelt dominated watershed (Sleepers, River, VT), and at a highly seasonal relatively low relief watershed (Panola Mt., Georgia). We monitored catchment runoff, internal hydrological response, and isotopic and solute dynamics for discrete riparian and hillslope zones within each catchment. Monitored catchment positions, including hillslope trenches at Maimai and Panola, were used to characterize directly, the hydrologic response and source water signatures for hillslope zones and riparian zones. We also examined the spatial and temporal source components of catchment stormflow using 3-component mass balance hydrograph separation techniques. At Maimai, NZ we found that hillslope runoff comprised 47-55% of total runoff during a 70 mm event. Despite the large amount of subsurface hillslope runoff in total catchment stormflow, riparian and channel zones accounted for 28% out of 29% of the total new water measured catchment runoff. Riparian water dominated the storm hydrograph composition early in the event, although hillslope water reached the catchment outlet soon after hillslope water tables were developed. Preliminary results for Sleepers River, VT and Panola Mountain, GA indicate that the timing and relative proportion of hillslope water in catchment runoff is later and smaller than at Maimai. Our multi-catchment comparison suggests that the ratio of the riparian reservoir to the hillslope reservoir/stormflow flux partially controls the relative contributions of hillslope and riparian zones to catchment runoff and solute dynamics.
ABSTRACT Dynamic thresholds in catchment response and subsurface stormflow initiation are poorly ... more ABSTRACT Dynamic thresholds in catchment response and subsurface stormflow initiation are poorly understood. This remains a problem for the generalization and transferability of hydrologic models, as well as for the simulation of catchment response under variable antecedent and input conditions. Threshold processes appear to operate both spatially and temporally within a catchment and introduce non-linearity to the system response function. We present a catchment intercomparison to illustrate the common features of threshold dynamics at the hillslope and catchment scales. While our overall goal is to generalize a model structure to work in humid areas where storm response is dominated by subsurface flow, cross-comparing internal catchment dynamics is a necessary prerequisite in order to define first order controls on the generation of subsurface stormflow across different landscape types. We analyzed physical data series collected from three catchments with extremely diverse climatic and physical characteristics: (1) Sleepers River Research Watershed in northeastern Vermont, USA; (2) Panola Mountain Research Watershed in central Georgia, USA; and (3) Maimai Watershed on the South Island of New Zeeland. The physical data series included continuous runoff, soil moisture probes, wells, piezometers and, for some catchments, tensiometers and hillslope trench flow. We calculated indices that characterized the timing, magnitude and duration of subsurface response in relation to stream discharge for a large number of events within each catchment. Analysis of these indices across space and time revealed distinguishable patterns of threshold behavior in the different catchments and our presentation will demonstrate the value of catchment intercomparision in this regard.
The goals for water-quality and ecosystem integrity are often defined relative to &am... more The goals for water-quality and ecosystem integrity are often defined relative to "natural" reference conditions in many water-management systems, including the European Union Water Framework Directive. This paper examines the difficulties created for water management by using "natural" as the goal. These difficulties are articulated from different perspectives in an informal (fictional) conversation that takes place after a workshop on reference conditions in water-resources management. The difficulties include defining the natural state and modeling how a system might be progressed toward the natural, as well as the feasibility and desirability of restoring a natural state. The paper also considers the appropriateness for developing countries to adopt the use of natural as the goal for water management. We conclude that failure to critically examine the complexities of having…
Peaks in phosphorus concentrations are observed in connection to the spring flood in some, mainly... more Peaks in phosphorus concentrations are observed in connection to the spring flood in some, mainly unregulated, rivers in northern Sweden draining to the Baltic Sea. The elevated concentrations are only seen during a few days prior and following peak discharge in the rivers. This rapid event is often missed by the water quality monitoring programme with a standard monthly sampling frequency. As a consequence, calculated transport of phosphorus, both from interpolation of measurements and from simulations by models calibrated using observed time series may therefore be significantly lower than the actual transport. Possible explanations of this phenomenon were investigated using two numerical water quality models, the HYPE and HBV-NP models. The hypothesis was that the observed peaks in phosphorus concentrations were due to either river bank erosion, flash-out of previously settled phosphorus-laden particles in rivers and/or elevated loading from land in connection to snowmelt in the ...
Water management in Sweden is focused on characterization of water bodies and establishing action... more Water management in Sweden is focused on characterization of water bodies and establishing action plans to achieve a good ecological status according to the framework directives stated by the European Union. To support this work SMHI has been commissioned to make databases of hydrography, statistics, water flows and scenario models freely available on the web. As a result of this we have created the open website vattenweb.smhi.se. The site currently provides observed and modeled data for fresh water and coastal areas as time series and statistics. In addition to this, the site also exposes data on wetlands and results from climate scenario simulations. The development of the site has been done in close cooperation with the end users at the water authorities to meet their needs and requirements. This has resulted in an easy to use website, where downloaded data easily can be imported into other tools for further use and analysis by the users. However, during the process we discovered...
Flow Pathways on Steep Forested Hillslopes: the Tracer, Tensiometer and Trough Approach Jeffrey M... more Flow Pathways on Steep Forested Hillslopes: the Tracer, Tensiometer and Trough Approach Jeffrey MCDONNELL* 1, Dean BRAMMER* 1, Carol KENDALL* 2, Niclas HJERDT* 1, Lindsay ROWE*\ Mike STEWART* 4 and Ross WOODS* 5 * 1 SUNY-ESF. 1 Forestry Drive. ...
Abstract Log floating in the 19th to mid 20th centuries has profoundly changed the environmental ... more Abstract Log floating in the 19th to mid 20th centuries has profoundly changed the environmental conditions in many northern river systems of the world. Regulation of flow by dams, straightening and narrowing of channels by various piers and wing dams, and homogenization of bed structure are some of the major impacts. As a result, the conditions for many riverine organisms have been altered. Removing physical constructions and returning boulders to the channels can potentially restore conditions for these organisms. ...
ABSTRACT In a steep, forested headwater catchment at Sleepers River, Vermont, research during the... more ABSTRACT In a steep, forested headwater catchment at Sleepers River, Vermont, research during the 1990s identified two discreet groundwater regimes: (1) a riparian zone, in which discharging groundwater creates a well-mixed aquifer with chemistry stoichiometrically similar to streamwater, and (2) a hillslope zone, with chemistry that varies widely but is generally quite different from streamwater. In contrast to the damped changes in riparian groundwater levels, the water table in hillslope positions increased a meter or more during large events, peaking after the streamflow peak. Despite the strong hydrologic dynamics in the hillslope, the chemistry of hillslope water, most notably its high Si concentration, was not detected in streamwater. More recent study has revealed a continuum of subsurface environments, with groundwater chemistry approaching streamwater stoichiometry along convergent flow paths. However, the fate of the high Si concentrations in hillslope groundwater has not been satisfactorily explained. Whereas past studies assumed conservative mixing of source waters, the aim of this presentation is to synthesize and reinterpret these past studies by giving greater consideration to potential biogeochemical reactions through the use of equilibrium modeling
ABSTRACT Few measures exist for objectively comparing the chemistry of streams. We develop a mult... more ABSTRACT Few measures exist for objectively comparing the chemistry of streams. We develop a multivariate technique, based on an eigenvalue analysis of streamwater concentrations, to facilitate comparison of water quality among sites across basin scales. A correlation matrix is constructed to include only solutes that mix conservatively. An eigenvalue analysis of this matrix is performed at each site to determine the approximate rank of the data set. If the ranks of all sites are roughly equal, one site is chosen as the reference site. The reduced set of eigenvectors from this site is chosen as the basis for a new, lower dimensional coordinate system and the data from the other sites are projected into this coordinate system. To assess the relative orientation of data from the reference site to all of the other sites, the relative bias (RB) and relative root mean square error (RRMSE) are calculated between the original and the projected points. The new technique was applied to multiple sites within three experimental watersheds to assess the consistency of water quality across the basin scale. The three watersheds were: Panola Mountain, Georgia, USA (6 solutes, 8 sites, 3 to 1000 ha); Sleepers River, Vermont, USA (5 solutes, 7 sites, 3 to 840 ha); and Maimai, South Island, New Zealand (4 solutes, 4 sites, 3 to 300 ha). Data from all sites were roughly planar with the first two eigenvectors explaining more than 90% of the variation. The RRMSEs for the reference site were generally between 5 and 10% with
ABSTRACT It is often assumed that hillslope and riparian areas constitute the two most important ... more ABSTRACT It is often assumed that hillslope and riparian areas constitute the two most important and identifiable landscape units contributing to catchment runoff in upland humid catchments. Nevertheless, the relative amount and timing of hillslope versus riparian contributions to stormflow are poorly understood across different watersheds. We quantified the contributions of hillslopes and riparian zones to stormflow using physical, chemical, and isotopic techniques across 3 diverse ({ ~}15 ha) headwater catchments: a highly responsive steep wet watershed (Maimai, New Zealand), a moderately steep snowmelt dominated watershed (Sleepers, River, VT), and at a highly seasonal relatively low relief watershed (Panola Mt., Georgia). We monitored catchment runoff, internal hydrological response, and isotopic and solute dynamics for discrete riparian and hillslope zones within each catchment. Monitored catchment positions, including hillslope trenches at Maimai and Panola, were used to characterize directly, the hydrologic response and source water signatures for hillslope zones and riparian zones. We also examined the spatial and temporal source components of catchment stormflow using 3-component mass balance hydrograph separation techniques. At Maimai, NZ we found that hillslope runoff comprised 47-55% of total runoff during a 70 mm event. Despite the large amount of subsurface hillslope runoff in total catchment stormflow, riparian and channel zones accounted for 28% out of 29% of the total new water measured catchment runoff. Riparian water dominated the storm hydrograph composition early in the event, although hillslope water reached the catchment outlet soon after hillslope water tables were developed. Preliminary results for Sleepers River, VT and Panola Mountain, GA indicate that the timing and relative proportion of hillslope water in catchment runoff is later and smaller than at Maimai. Our multi-catchment comparison suggests that the ratio of the riparian reservoir to the hillslope reservoir/stormflow flux partially controls the relative contributions of hillslope and riparian zones to catchment runoff and solute dynamics.
ABSTRACT Dynamic thresholds in catchment response and subsurface stormflow initiation are poorly ... more ABSTRACT Dynamic thresholds in catchment response and subsurface stormflow initiation are poorly understood. This remains a problem for the generalization and transferability of hydrologic models, as well as for the simulation of catchment response under variable antecedent and input conditions. Threshold processes appear to operate both spatially and temporally within a catchment and introduce non-linearity to the system response function. We present a catchment intercomparison to illustrate the common features of threshold dynamics at the hillslope and catchment scales. While our overall goal is to generalize a model structure to work in humid areas where storm response is dominated by subsurface flow, cross-comparing internal catchment dynamics is a necessary prerequisite in order to define first order controls on the generation of subsurface stormflow across different landscape types. We analyzed physical data series collected from three catchments with extremely diverse climatic and physical characteristics: (1) Sleepers River Research Watershed in northeastern Vermont, USA; (2) Panola Mountain Research Watershed in central Georgia, USA; and (3) Maimai Watershed on the South Island of New Zeeland. The physical data series included continuous runoff, soil moisture probes, wells, piezometers and, for some catchments, tensiometers and hillslope trench flow. We calculated indices that characterized the timing, magnitude and duration of subsurface response in relation to stream discharge for a large number of events within each catchment. Analysis of these indices across space and time revealed distinguishable patterns of threshold behavior in the different catchments and our presentation will demonstrate the value of catchment intercomparision in this regard.
The goals for water-quality and ecosystem integrity are often defined relative to &am... more The goals for water-quality and ecosystem integrity are often defined relative to "natural" reference conditions in many water-management systems, including the European Union Water Framework Directive. This paper examines the difficulties created for water management by using "natural" as the goal. These difficulties are articulated from different perspectives in an informal (fictional) conversation that takes place after a workshop on reference conditions in water-resources management. The difficulties include defining the natural state and modeling how a system might be progressed toward the natural, as well as the feasibility and desirability of restoring a natural state. The paper also considers the appropriateness for developing countries to adopt the use of natural as the goal for water management. We conclude that failure to critically examine the complexities of having…
Peaks in phosphorus concentrations are observed in connection to the spring flood in some, mainly... more Peaks in phosphorus concentrations are observed in connection to the spring flood in some, mainly unregulated, rivers in northern Sweden draining to the Baltic Sea. The elevated concentrations are only seen during a few days prior and following peak discharge in the rivers. This rapid event is often missed by the water quality monitoring programme with a standard monthly sampling frequency. As a consequence, calculated transport of phosphorus, both from interpolation of measurements and from simulations by models calibrated using observed time series may therefore be significantly lower than the actual transport. Possible explanations of this phenomenon were investigated using two numerical water quality models, the HYPE and HBV-NP models. The hypothesis was that the observed peaks in phosphorus concentrations were due to either river bank erosion, flash-out of previously settled phosphorus-laden particles in rivers and/or elevated loading from land in connection to snowmelt in the ...
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Papers by Niclas Hjerdt