| 1. |
- Kruitbos, L. M., et al.
(författare)
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Hydroclimatic and hydrochemical controls on Plecoptera diversity and distribution in northern freshwater ecosystems
- 2012
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 693:1, s. 39-53
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Tidskriftsartikel (refereegranskat)abstract
- Freshwater ecosystems in the mid- to upper-latitudes of the northern hemisphere are particularly vulnerable to the impact of climate change as slight changes in air temperature can alter the form, timing, and magnitude of precipitation and consequent influence of snowmelt on streamflow dynamics. Here, we examine the effects of hydro-climate, flow regime, and hydrochemistry on Plecoptera (stonefly) alpha (alpha) diversity and distribution in northern freshwater ecosystems. We characterized the hydroclimatic regime of seven catchments spanning a climatic gradient across the northern temperate region and compared them with estimates of Plecoptera genera richness. By a space-for-time substitution, we assessed how warmer temperatures and altered flow regimes may influence Plecoptera alpha diversity and composition at the genus level. Our results show wide hydroclimatic variability among sites, including differences in temporal streamflow dynamics and temperature response. Principal component analysis showed that Plecoptera genera richness was positively correlated with catchment relief (m), mean and median annual air temperature (A degrees C), and streamflow. These results provide a preliminary insight into how hydroclimatic change, particularly in terms of increased air temperature and altered streamflow regimes, may create future conditions more favorable to some Plecopteras in northern catchments.
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| 2. |
- Laudon, Hjalmar, et al.
(författare)
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Cross-regional prediction of long-term trajectory of stream water DOC response to climate change
- 2012
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Ingår i: Geophysical Research Letters. - : John Wiley & Sons. - 0094-8276 .- 1944-8007. ; 39
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Tidskriftsartikel (refereegranskat)abstract
- There is no scientific consensus about how dissolved organic carbon (DOC) in surface waters is regulated. Here we combine recent literature data from 49 catchments with detailed stream and catchment process information from nine well established research catchments at mid- to high latitudes to examine the question of how climate controls stream water DOC. We show for the first time that mean annual temperature (MAT) in the range from -3 degrees to +10 degrees C has a strong control over the regional stream water DOC concentration in catchments, with highest concentrations in areas ranging between 0 degrees and +3 degrees C MAT. Although relatively large deviations from this model occur for individual streams, catchment topography appears to explain much of this divergence. These findings suggest that the long-term trajectory of stream water DOC response to climate change may be more predictable than previously thought. Citation: Laudon, H., J. Buttle, S. K. Carey, J. McDonnell, K. McGuire, J. Seibert, J. Shanley, C. Soulsby, and D. Tetzlaff (2012), Cross-regional prediction of long-term trajectory of stream water DOC response to climate change, Geophys. Res. Lett., 39, L18404, doi: 10.1029/2012GL053033.
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| 3. |
- Egli, M., et al.
(författare)
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Rapid transformation of inorganic to organic and plant-available phosphorous in soils of a glacier forefield
- 2012
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Ingår i: Geoderma. - : Elsevier. - 0016-7061. ; 189-190, s. 215-226
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Tidskriftsartikel (refereegranskat)abstract
- Chemical weathering of rocks or sediments is extremely important for the generation of soils, for the evolution of landscape, and as a main source of inorganic nutrients for plant growth and therefore for life. Temporal trends in weathering mechanisms, plant succession and nutrients availability in cold environments can be successfully studied in soil chronosequences along a glacier forefield. In the present paper, this was carried out in the pro-glacial area of Morteratsch. Different forms of phosphorous in the soil, stream and spring water chemistry were investigated. Apatite constitutes the main source of P, but it occurs only as a minor accessory mineral phase in the granitic/gneiss parent material. The identification of apatite was performed using SEM-EDX and cathodoluminescence. Water chemistry data indicated some calcite dissolution at the earliest phase of exposure, pyrite and - on older surfaces increasingly - feldspar weathering. Apatite also seemed to contribute to Ca which is leached from the soils. The concentrations of dissolved P in the stream and spring waters were, however, extremely low (only a few μg P/l). In the topsoil, the total stocks of P showed a slight decrease with time. Losses were rather difficult to detect even though the water fluxes through the soils and discharges are relatively high. Soil organic P is almost identical to the EDTA-extractable fraction. In an 11.5. ky-old soil outside the glacier forefield the concentration and proportions of organic P, EDTA-extractable P and inorganic P forms did not differ that much from the oldest soils (max. 150. years) of the glacier forefield. In the bulk soil, about 78% of total P was transformed into an organic form (40% already after 150. years) and, in the fine earth, about 81% (40-70% after about 150. years of soil evolution). Thus the P transformation reactions are shown to be very rapid, occur predominantly in the early phase of soil formation, and could be best described by an exponential decay model. © 2012 Elsevier B.V.
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| 4. |
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| 5. |
- Geris, J., et al.
(författare)
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Conceptual modelling to assess hydrological impacts and evaluate environmental flow scenarios in montane river systems regulated for hydropower
- 2014
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Ingår i: Rivers Research and Applications. - : Wiley. - 1535-1459 .- 1535-1467.
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Tidskriftsartikel (refereegranskat)abstract
- To improve understanding of natural and managed flow regimes in data-sparse regulated river systems in montane areas, the commonly used Hydrologiska Byråns Vattenbalansavdelning (HBV) conceptual run-off model was adapted to incorporate water regulation components. The extended model was then applied to the heavily regulated river Lyon (391 km2) in Scotland to reconstruct the natural flow regime and to assess the impacts of regulation at increasing spatial scales. Multi-criteria model evaluation demonstrated that the model performed well in capturing the dominant catchment processes and regulation effects, especially at the timescales at which operation rules apply. The main change as a result of regulation in the river Lyon is a decrease in inter-annual and intra-annual variability of all elements of the flow regime, in terms of magnitude, frequency, and duration. Although these impacts are most pronounced directly downstream of the impoundments, the regulation effects propagate throughout the river system. The modelling approach is flexible and widely applicable and only limited amounts of data are required. Moreover, results are easily communicated to stakeholders. It has the potential to contribute to the development of flow regimes that may be more beneficial to the ecological status of rivers. In the case of the river Lyon, it is likely that this involves a more variable release regime. The approach developed here provides a tool for assessing impacts on flow regimes and informing environmental flows in other data-sparse regions with heavily regulated montane river systems. Copyright © 2014 John Wiley & Sons, Ltd.
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| 6. |
- Rinderer, M., et al.
(författare)
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Topographic controls on shallow groundwater levels in a steep, prealpine catchment : When are the TWI assumptions valid?
- 2014
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Ingår i: Water resources research. - 0043-1397 .- 1944-7973. ; 50:7, s. 6067-6080
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Tidskriftsartikel (refereegranskat)abstract
- Topographic indices like the Topographic Wetness Index (TWI) have been used to predict spatial patterns of average groundwater levels and to model the dynamics of the saturated zone during events (e. g., TOPMODEL). However, the assumptions underlying the use of the TWI in hydrological models, of which the most important is that groundwater level variation can be approximated by a series of steady state situations, are rarely tested. It is also not clear how well findings from existing hillslope studies on sites with transmissive soil can be transferred to entire catchments with less permeable soils. This study, therefore, evaluated the suitability of selected topographic indices to describe spatial groundwater level variations based on time series from 51 groundwater wells in a 20 ha catchment with low-permeability soils in Switzerland. Results showed that median groundwater levels were correlated to slope, curvature, and TWI, but the strength of correlation depended on whether the indices characterized the local topography or the topography of the upslope contributing area. The correlation between TWI and groundwater levels was not constant over time but decreased at the beginning of rainfall events, indicating large spatial differences in groundwater responses, and increased after peak flow, when groundwater levels could be considered to be spatially in a steady state. Our findings indicate that topographic indices are useful to predict median groundwater levels in catchments with low-permeability soils and that the TWI assumptions are best met when groundwater levels change slowly.
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| 7. |
- van Meerveld, H. J. Ilja, et al.
(författare)
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Information content of stream level class data for hydrological model calibration
- 2017
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Ingår i: Hydrology and Earth System Sciences. - : COPERNICUS GESELLSCHAFT MBH. - 1027-5606 .- 1607-7938. ; 21:9, s. 4895-4905
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Tidskriftsartikel (refereegranskat)abstract
- Citizen science can provide spatially distributed data over large areas, including hydrological data. Stream levels are easier to measure than streamflow and are likely also observed more easily by citizen scientists than streamflow. However, the challenge with crowd based stream level data is that observations are taken at irregular time intervals and with a limited vertical resolution. The latter is especially the case at sites where no staff gauge is available and relative stream levels are observed based on (in) visible features in the stream, such as rocks. In order to assess the potential value of crowd based stream level observations for model calibration, we pretended that stream level observations were available at a limited vertical resolution by transferring streamflow data to stream level classes. A bucket-type hydrological model was calibrated with these hypothetical stream level class data and subsequently evaluated on the observed streamflow records. Our results indicate that stream level data can result in good streamflow simulations, even with a reduced vertical resolution of the observations. Time series of only two stream level classes, e.g. above or below a rock in the stream, were already informative, especially when the class boundary was chosen towards the highest stream levels. There was some added value in using up to five stream level classes, but there was hardly any improvement in model performance when using more level classes. These results are encouraging for citizen science projects and provide a basis for designing observation systems that collect data that are as informative as possible for deriving model based streamflow time series for previously ungauged basins.
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| 8. |
- Westerberg, Ida K., et al.
(författare)
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Regional water balance modelling using flow-duration curves with observational uncertainties
- 2014
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 18:8, s. 2993-3013
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Tidskriftsartikel (refereegranskat)abstract
- Robust and reliable water-resource mapping in ungauged basins requires estimation of the uncertainties in the hydrologic model, the regionalisation method, and the observational data. In this study we investigated the use of regionalised flow-duration curves (FDCs) for constraining model predictive uncertainty, while accounting for all these uncertainty sources. A water balance model was applied to 36 basins in Central America using regionally and globally available precipitation, climate and discharge data that were screened for inconsistencies. A rating-curve analysis for 35 Honduran discharge stations was used to estimate discharge uncertainty for the region, and the consistency of the model forcing and evaluation data was analysed using two different screening methods. FDCs with uncertainty bounds were calculated for each basin, accounting for both discharge uncertainty and, in many cases, uncertainty stemming from the use of short time series, potentially not representative for the modelling period. These uncertain FDCs were then used to regionalise a FDC for each basin, treating it as ungauged in a cross-evaluation, and this regionalised FDC was used to constrain the uncertainty in the model predictions for the basin. There was a clear relationship between the performance of the local model calibration and the degree of data set consistency - with many basins with inconsistent data lacking behavioural simulations (i.e. simulations within predefined limits around the observed FDC) and the basins with the highest data set consistency also having the highest simulation reliability. For the basins where the regionalisation of the FDCs worked best, the uncertainty bounds for the regionalised simulations were only slightly wider than those for a local model calibration. The predicted uncertainty was greater for basins where the result of the FDC regionalisation was more uncertain, but the regionalised simulations still had a high reliability compared to the locally calibrated simulations and often encompassed them. The regionalised FDCs were found to be useful on their own as a basic signature constraint; however, additional regionalised signatures could further constrain the uncertainty in the predictions and may increase the robustness to severe data inconsistencies, which are difficult to detect for ungauged basins.
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| 9. |
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| 10. |
- Archfield, Stacey A., et al.
(författare)
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Accelerating advances in continental domain hydrologic modeling
- 2015
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Ingår i: Water resources research. - 0043-1397 .- 1944-7973. ; 51:12, s. 10078-10091
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Tidskriftsartikel (refereegranskat)abstract
- In the past, hydrologic modeling of surface water resources has mainly focused on simulating the hydrologic cycle at local to regional catchment modeling domains. There now exists a level of maturity among the catchment, global water security, and land surface modeling communities such that these communities are converging toward continental domain hydrologic models. This commentary, written from a catchment hydrology community perspective, provides a review of progress in each community toward this achievement, identifies common challenges the communities face, and details immediate and specific areas in which these communities can mutually benefit one another from the convergence of their research perspectives. Those include: (1) creating new incentives and infrastructure to report and share model inputs, outputs, and parameters in data services and open access, machine-independent formats for model replication or reanalysis; (2) ensuring that hydrologic models have: sufficient complexity to represent the dominant physical processes and adequate representation of anthropogenic impacts on the terrestrial water cycle, a process-based approach to model parameter estimation, and appropriate parameterizations to represent large-scale fluxes and scaling behavior; (3) maintaining a balance between model complexity and data availability as well as uncertainties; and (4) quantifying and communicating significant advancements toward these modeling goals.
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