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  • 1.
    Andersson, Lotta
    et al.
    SMHI, Samhälle och säkerhet.
    Rosberg, Jörgen
    SMHI, Forskningsavdelningen, Hydrologi.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Estimating catchment nutrient flow with the HBV-NP model: Sensitivity to input data2005Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 34, nr 7, s. 521-532Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dynamic catchment model HBV-N has been further developed by adding routines for phosphorus transport and is now called the HBV-NP model. The model was shown to satisfactorily simulate nutrient dynamics in the Ronnea catchment (1 900 km(2)). Its sensitivity to input data was tested, and results demonstrated the increased sensitivity to the selection of input data on a subcatchment scale when compared with the catchment scale. Selection of soil and land use databases was found to be critical in some subcatchments but did not have a significant impact on a catchment scale. Although acceptable on a catchment scale, using templates and generalization, with regards to emissions from point sources and rural households, significantly decreased model performance in certain subcatchments when compared with using more detailed local information. A division into 64 subcatchments resulted in similar model performance at the catchment outlet when compared with a lumped approach. Adjusting the imported matrixes of the regional leaching of nitrogen, from agricultural land, against mean subcatchment water percolation did not have a significant impact on the model performance.

  • 2.
    Arheimer, Berit
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Andersson, Lotta
    SMHI, Samhälle och säkerhet.
    Larsson, M
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Modelling diffuse nutrient flow in eutrophication control scenarios2004Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 49, nr 3, s. 37-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Swedish Water Management Research Programme (VASTRA) focuses on the development and demonstration of tools for more efficient eutrophication control when implementing the EU water framework directive in Sweden. During the first half of the programme, models for nitrogen flow were developed, and at present, similar models for phosphorus are under construction (e.g. HBV-P). The programme is interdisciplinary, and scientists are collaborating in actor-games and focus group evaluations including scenario analysis. The scenarios modelled in VASTRA phase 1, show that (i) changed agricultural practices can be the most effective and-least expensive way to reduce nitrogen transport from land to, the sea; (ii) constructed agricultural wetlands may only have small impact on riverine nitrogen transport in some regions, due to natural hydrometeorological dynamics; (iii) removing planktivorous fish may be an efficient way of reducing the algal concentrations in lakes without the undesired side-effect of increased nutrient load to the down-stream river system. In VASTRA phase 11, one of the highlights will be interdisciplinary scenario-modelling of different measure strategies in a pilot catchment of southern Sweden (Ronne a).

  • 3.
    Arheimer, Berit
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Andreasson, Johan
    SMHI, Affärsverksamhet.
    Fogelberg, S
    Johnsson, H
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Persson, K
    Climate change impact on water quality: Model results from southern Sweden2005Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 34, nr 7, s. 559-566Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Starting from six regional climate change scenarios, nitrogen leaching from arable-soil, water discharge, and nitrogen retention was modeled in the Ronnea catchment. Additionally, biological response was modeled in the eutrophic Lake Ringsjon. The results are compared with similar studies on other catchments. All scenarios gave similar impact on water quality but varied in quantities. However, one scenario resulted in a different transport pattern due to less-pronounced seasonal variations in the hydrology. On average, the study shows that, in a future climate, we might expect: i) increased concentrations of nitrogen in the arable root zone (+50%) and in the river (+13%); ii) increased annual load of nitrogen from land to sea (+22%) due to more pronounced winter high flow; moreover, remote areas in the catchment may start to contribute to the outlet load; iii) radical changes in lake biochemistry with increased concentrations of total phosphorus (+50%), total nitrogen (+20%), and planktonic algae such as cyanobacteria (+80%).

  • 4.
    Arheimer, Berit
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Lowgren, M
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Rosberg, Jörgen
    SMHI, Forskningsavdelningen, Hydrologi.
    Integrated catchment modeling for nutrient reduction: Scenarios showing impacts, potential, and cost of measures2005Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 34, nr 7, s. 513-520Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A hydrological-based model (HBV-NP) was applied to a catchment (1900 km(2)) in the southern part of Sweden. Careful characterization of the present load situation and the potential for improved treatment or reduced soil leaching were analyzed. Several scenarios were modeled to find strategies to reach the Swedish environmental goals of reducing anthropogenic nitrogen load by 30% and phosphorus load by 20%. It was stated that the goals could be reached by different approaches that would affect different polluters and social sectors. However, no single measure was enough by itself. Instead, a combination of measures was necessary to achieve the goals. The nitrogen goal was the most difficult to attain. In order to be cost-effective, these measures should be applied to areas contributing the most to the net loading of the sea. This strategy could reduce the costs by 70%-80% when compared with implementing the measures in the entire catchment. Integrated catchment models may thus be helpful tools for reducing costs in environmental control programs.

  • 5.
    Arheimer, Berit
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Kväveretention i svenska sjöar och vattendrag – betydelse för utsläpp från reningsverk2007Rapport (Annet vitenskapelig)
    Abstract [sv]

    Den här rapporten har tagits fram på uppdrag av Naturvårdsverket för att underlätta diskussionen med EU-kommissionen, som har annonserat att den tänker stämma Sverige inför EU-domstolen för otillräckligt genomförande av avloppsdirektivet. Vid bedömningen av vilka reningsverk som omfattas av krav på kväverening tas i Sverige hänsyn till den naturliga avskiljning (retention) som sker i vattendrag under transporten från utsläppskälla till havet.Kväveretention är ett vedertaget begrepp som inkluderar ett flertal naturliga biogeokemiska processer som permanent reducerar kväve från vattenfasen i sjöar och vattendrag. Speciellt stor är effekten i sjörika områden. Naturlig retention är dock svår att mäta. I Sverige har man utvecklat ett modellsystem för storskalig beräkning av närsalttransport, inklusive retention, från land till hav med relativt hög geografisk upplösning. Systemet kopplar fältskalemodeller med avrinningsmodeller (HBV-NP), är vetenskapligt dokumenterat och granskat och har tillämpats storskaligt sedan 1997 för internationell rapportering till HELCOM.Det är stor skillnad i sjöars retentionskapacitet; i norra delarna av landet är den låg medan sjöarna i de södra delarna av landet är betydligt effektivare som kvävesänkor. Totalt reduceras ca 30 000 tonkväve per år i sjöar och vattendrag, varav 70% i södra Sverige.De reningsverk vars utsläpp passerar fler sjöar får liten påverkan på havet. Naturlig kväveretention i vattendrag och sjöar reducerar de svenska reningsverkens bidrag till kusten med 3200 ton/år, vilketmotsvarar 18% av reningsverkens totala utsläpp. Retentionen varierar dock betydligt mellan olika delar av landet. De flesta reningsverk med större utsläpp finns längs kusten och i södra Sverige.

  • 6.
    Arheimer, Berit
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Lessons learned? Effects of nutrient reductions from constructing wetlands in 1996–2006 across Sweden2016Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, s. 1-11Artikkel i tidsskrift (Fagfellevurdert)
  • 7. Dahl, M
    et al.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Comparison of four models simulating phosphorus dynamics in Lake Vanern, Sweden2004Inngår i: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 8, nr 6, s. 1153-1163Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper compares four water quality models applied to Lake Vanern, Sweden. The comparison is focused on phosphorus, the primary limiting nutrient in Lake Vanern. Two of the models, FYRISA and HBV-NP, are simple and were developed as parts of catchment models. Two other models, called LEEDS and MOM are more comprehensive lake models. The models were calibrated using data from the period 1985-1992 and validated using data from the period 1993-2000. The fit to calibration data is similar for the FYRISA, HBV-NP, and LEEDS models, and slightly worse for the BIOLA model. All models fit the validation data almost as well as the calibration data. The models behaviour was tested in two representative scenarios. An increase of emissions by 40% from a pulp and paper mill has a negligible effect on the water quality, while a decrease in phosphorus load by 14% (accomplished by better waste-water treatment in rural households) gives a considerable decrease in phosphorus concentration in the lake. Still, the results of the scenarios vary between the models.

  • 8. Hankin, Barry
    et al.
    Strömqvist, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Burgess, Chris
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Bielby, Sally
    Revilla-Romero, Beatriz
    Pope, Linda
    A New National Water Quality Model to Evaluate the Effectiveness of Catchment Management Measures in England2019Inngår i: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 11, nr 8, artikkel-id 1612Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This investigation reports on a new national model to evaluate the effectiveness of catchment sensitive farming in England, and how pollution mitigation measures have improved water quality between 2006 and 2016. An adapted HYPE (HYdrological Predictions for the Environment) model was written to use accurate farm emissions data so that the pathway impact could be accounted for in the land phase of transport. Farm emissions were apportioned into different runoff fractions simulated in surface and soil layers, and travel time and losses were taken into account. These were derived from the regulator's catchment change matrix' and converted to monthly load time series, combined with extensive point source load datasets. Very large flow and water quality monitoring datasets were used to calibrate the model nationally for flow, nitrogen, phosphorus, suspended sediments and faecal indicator organisms. The model was simulated with and without estimated changes to farm emissions resulting from catchment measures, and spatial and temporal changes to water quality concentrations were then assessed.

  • 9. Lewerin, S. S.
    et al.
    Sokolova, E.
    Wahlstrom, H.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Strömqvist, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Soren, K.
    Potential infection of grazing cattle via contaminated water: a theoretical modelling approach2019Inngår i: Animal, ISSN 1751-7311, E-ISSN 1751-732X, Vol. 13, nr 9, s. 2052-2059, artikkel-id PII S1751731118003415Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wastewater discharge and agricultural activities may pose microbial risks to natural water sources. The impact of different sources can be assessed by water quality modelling. The aim of this study was to use hydrological and hydrodynamic models to illustrate the risk of exposing grazing animals to faecal pollutants in natural water sources, using three zoonotic faecal pathogens as model microbes and fictitious pastures in Sweden as examples. Microbial contamination by manure from fertilisation and grazing was modelled by use of a hydrological model (HYPE) and a hydrodynamic model (MIKE 3 FM), and microbial contamination from human wastewater was modelled by application of both models in a backwards process. The faecal pathogens Salmonella spp., verotoxin-producing Escherichia coli O157:H7 (VTEC) and Cryptosporidium parvum were chosen as model organisms. The pathogen loads on arable land and pastures were estimated based on pathogen concentration in cattle faeces, herd prevalence and within-herd prevalence. Contamination from human wastewater discharge was simulated by estimating the number of pathogens required from a fictitious wastewater discharge to reach a concentration high enough to cause infection in cattle using the points on the fictitious pastures as their primary source of drinking water. In the scenarios for pathogens from animal sources, none of the simulated concentrations of salmonella exceeded the concentrations needed to infect adult cattle. For VTEC, most of the simulated concentrations exceeded the concentration needed to infect calves. For C. parvum, all the simulated concentrations exceeded the concentration needed to infect calves. The pathogen loads needed at the release points for human wastewater to achieve infectious doses for cattle were mostly above the potential loads of salmonella and VTEC estimated to be present in a 24-h overflow from a medium-size Swedish wastewater treatment plant, while the required pathogen loads of C. parvum at the release points were below the potential loads of C. parvum in a 24-h wastewater overflow. Most estimates in this study assume a worst-case scenario. Controlling zoonotic infections at herd level prevents environmental contamination and subsequent human exposure. The potential for infection of grazing animals with faecal pathogens has implications for keeping animals on pastures with access to natural water sources. As the infectious dose for most pathogens is more easily reached for calves than for adult animals, and young calves are also the main shedders of C. parvum, keeping young calves on pastures adjacent to natural water sources is best avoided.

  • 10.
    Lindström, Göran
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Rosberg, Jörgen
    SMHI, Forskningsavdelningen, Hydrologi.
    Strömqvist, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Development and testing of the HYPE (Hydrological Predictions for the Environment) water quality model for different spatial scales2010Inngår i: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 41, nr 3-4, s. 295-319Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The HYPE model is a hydrological model for small-scale and large-scale assessments of water resources and water quality, developed at the Swedish Meteorological and Hydrological Institute during 2005-2007. In the model, the landscape is divided into classes according to soil type, land use and altitude. In agricultural lands the soil is divided into three layers, each with individual computations of soil wetness and nutrient processes. The model simulates water flow and transport and turnover of nitrogen and phosphorus. Nutrients follow the same pathways as water in the model: surface runoff, macropore flow, tile drainage and outflow from individual soil layers. Rivers and lakes are described separately with routines for turnover of nutrients in each environment. Model parameters are global, or coupled to soil type or land use. The model was evaluated both by local calibrations to internal variables from different test basins and to data on discharge and nutrients from a large number of small basins. In addition, the estimated parameters were transferred to two larger basins in southern Sweden: River Ronnea and River Vindan. The resulting simulations were generally in good agreement with observations.

  • 11.
    Olsson, Jonas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Bengtsson, Lisa
    SMHI, Forskningsavdelningen, Meteorologi.
    Pechlivanidis, Ilias
    SMHI, Forskningsavdelningen, Hydrologi.
    Berg, Peter
    Körnich, Heiner
    SMHI, Forskningsavdelningen, Meteorologi.
    Distance-dependent depth-duration analysis in high-resolution hydro-meteorological ensemble forecasting: A case study in Malmo City, Sweden2017Inngår i: Environmental Modelling & Software, ISSN 1364-8152, E-ISSN 1873-6726, Vol. 93, s. 381-397Artikkel i tidsskrift (Fagfellevurdert)
  • 12.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    BIOLA - Biogeochemical Lake Model Manual2003Rapport (Annet vitenskapelig)
  • 13.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    HBV-NP Model Manual2007Rapport (Annet vitenskapelig)
  • 14.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Model description of BIOLA - a biogeochemical lake model2002Rapport (Annet vitenskapelig)
    Abstract [en]

    The biogeochemical lake model BIOLA was developed to be used for eutrophication studies in

    Sweden

    . Eutrophication is a threat for lakes in populated areas, and this model was developed to be

    a tool for managing lakes suffering from eutrophication. There are several measures that can be

    taken to reduce eutrophication. When considering different measures simulations of their effects,

    with models such as BIOLA, can contribute with information.

    The model is a biogeochemical lake module coupled to a one-dimensional hydrodynamic model.

    The model simulates the continuous change of lake stratification and water quality due to weather,

    inflow

    , outflow and biogeochemical processes in the lake and in the sediments. It simulates changes

    over time in nutrient and biological state at different depths. The most important variables simulated

    by the model are inorganic nutrients and phytoplankton in the water. Other variables include

    nutrients and organic matter in the sediments.

    The model has shown to be able to simulate changing nutrient and plankton dynamics. The result

    from three studied lakes are reviewed.

  • 15.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Modeling the response of eutrophication control measures in a Swedish lake2005Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 34, nr 7, s. 552-558Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The response of a biogeochemical lake model (BIOLA) to different eutrophication management actions has been studied in a eutrophic lake. Management actions included in the study were nutrient load reduction, sediment manipulation, biomanipulation, and herbicide application. The model was used to simulate nutrient and biomass concentrations in the lake during the 1990s. During the same period, management scenarios were also simulated. Several ecological parameters were calibrated to better simulate the behavior of the chosen lake, but there were still some difficulties with phosphate. This indicated that further model development is necessary. The most favorable development within the lake was found for scenarios with nutrient load reduction and biomanipulation through planktivorous fish reduction. Reducing both the nitrogen and phosphorus loads had a greater effect on the lake's water quality than simply reducing just one of the nutrients.

  • 16.
    Pers, Charlotta
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Persson, I
    Simulation of a biogeochemical model in different lakes2003Inngår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 34, nr 5, s. 543-558Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Eutrophication, caused by nutrients leached from soil and emitted from point sources, is a well-known problem in many Swedish lakes. There are several countermeasures that can be used to reduce eutrophication. A model that can simulate the biogeochemical response to different management scenarios may help with nutrient reducing strategies. Results from applications with such a model to different types of lakes are presented in this paper. The most important variables simulated by the model are dissolved nutrient concentrations (nitrogen and phosphorus) and phytoplankton. Other variables include nitrogen fixating cyanobacteria, sediments, and zooplankton. In total, 14 state variables are simulated. Nutrients are supplied through tributaries, and the temperature and vertical mixing forced by meteorological input. The model is able to simulate effects of changing nutrients and plankton dynamics. It is promising as an instrument for evaluating various measures to improve water quality in lakes. However, for the lakes the model has been applied to, the model has been calibrated to available observations. Non-monitored lakes could also be interesting to simulate, therefore the parameters of the model set-ups are discussed in this paper.

  • 17.
    Pers, Charlotta
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Rahm, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Jonsson, A
    Bergstrom, A K
    Jansson, M
    Modelling dissolved organic carbon turnover in humic Lake Ortrasket, Sweden2001Inngår i: Environmental Modelling and Assessment, ISSN 1420-2026, E-ISSN 1573-2967, Vol. 6, nr 3, s. 159-172Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The organic carbon balance of a lake with high input of allochthonous organic carbon is modelled integrating physical, chemical and biological processes. The physical model captures the behaviour of real thermal stratification in the lake for different flow situations during the period 1993-1997. The dissolved organic carbon model is based on simulated trajectories of water parcels. By tracking parcels, account is kept of environmental factors such as temperature and radiation as well as DOC quality for each parcel, The DOC concentration shows seasonal variations primarily dependent on inflow. The organic matter degradation (bacterial- and photodegradation) in the lake amounts to 1.5-2.5 mg C l(-1) yr(-1), where photooxidation is responsible for approximately 10%. The estimated DIC production in the lake is large compared to sediment mineralisation and primary production. The main conclusion is that the model with the selected parameterisations of the degradation processes reasonably well describes the DOC dynamics in a forest lake.

  • 18.
    Pers, Charlotta
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Temnerud, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Modelling water, nutrients, and organic carbon in forested catchments: a HYPE application2016Inngår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 30, nr 18, s. 3252-3273Artikkel i tidsskrift (Fagfellevurdert)
  • 19.
    Strombäck, Lena
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Strömqvist, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Gustavsson, Jens
    SMHI.
    A web based analysis and scenario tool for eutrophication of inland waters for Sweden and Europe2019Inngår i: Environmental Modelling & Software, ISSN 1364-8152, E-ISSN 1873-6726, Vol. 111, s. 259-267Artikkel i tidsskrift (Fagfellevurdert)
  • 20. Tonderski, K S
    et al.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Modeling the impact of potential wetlands on phosphorus retention in a Swedish catchment2005Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 34, nr 7, s. 544-551Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In southern Sweden, wetlands are constructed to remove nitrogen (N) in agricultural catchments. The possible effects of such wetlands on riverine phosphorus (P) were also estimated using input-output data from three well-monitored wetlands. This was done to formulate a simple model for removal of P that is dependent on inflow characteristics. Next, the N- and P-reducing effects of wetlands were modeled on a catchment scale (1900 km 2) using the HBV-NP model and various assumptions about the wetland area and location. All three wetlands functioned as sinks for total P (tot-P) and for total suspended solids (TSS) with a removal of 10% to 31% and 28% to 50%, respectively. Mean P-removal rates of 17-49 kg ha(-1) yr(-1) were well simulated with the model. Catchment scale simulations indicated that wetlands were more efficient (in percentage of load) as traps for P than for N and that this may motivate the construction of wetlands for P removal far upstream from the catchment outlet.

  • 21. Winterdahl, Mattias
    et al.
    Laudon, Hjalmar
    Lyon, Steve W.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Bishop, Kevin
    Sensitivity of stream dissolved organic carbon to temperature and discharge: Implications of future climates2016Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, nr 1, s. 126-144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dissolved organic carbon (DOC) is a significant constituent in aquatic ecosystems with concentrations in streams influenced by both temperature and water flow pathway dynamics associated with changes in discharge (streamflow). We investigated the sensitivity of DOC concentrations in 12 high-latitude headwater streams to changes in temperature and discharge using a mathematical model. The implications of differences in sensitivities were explored by using downscaled projections of air temperature and discharge to simulate possible trajectories of DOC concentrations in a changing climate. We found two distinct responses: (i) catchments where stream DOC sensitivity was high to temperature but low to discharge and (ii) catchments where stream DOC sensitivity was low to temperature but high to discharge. Streams with strong seasonal DOC dynamics were more sensitive to temperature changes than nonseasonal systems. In addition, stream DOC sensitivity to discharge was strongly correlated with vertical soil water DOC differences in the near-stream zone. Simulations of possible future changes in DOC concentrations indicated median increases of about 4-24% compared to current levels when using projections of air temperature and discharge but even larger increases were observed for base flow concentrations (13-42%). Streams with high-temperature sensitivity showed the largest increases in DOC concentrations. Our results suggest that future climatic changes could bring significant increases in surface water DOC concentrations in boreal and hemiboreal areas but that the response ultimately is dependent on vertical soil solution DOC differences and soil organic carbon distribution.

  • 22. Yin, Yunxing
    et al.
    Jiang, Sanyuan
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Yang, Xiaoying
    Liu, Qun
    Yuan, Jin
    Yao, Mingxing
    He, Yi
    Luo, Xingzhang
    Zheng, Zheng
    Assessment of the Spatial and Temporal Variations of Water Quality for Agricultural Lands with Crop Rotation in China by Using a HYPE Model2016Inngår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 13, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many water quality models have been successfully used worldwide to predict nutrient losses from anthropogenically impacted catchments, but hydrological and nutrient simulations with limited data are difficult considering the transfer of model parameters and complication of model calibration and validation. This study aims: (i) to assess the performance capabilities of a new and relatively more advantageous model, namely, Hydrological Predictions for the Environment (HYPE), that simulates stream flow and nutrient load in agricultural areas by using a multi-site and multi-objective parameter calibration method and (ii) to investigate the temporal and spatial variations of total nitrogen (TN) and total phosphorous (TP) concentrations and loads with crop rotation by using the model for the first time. A parameter estimation tool (PEST) was used to calibrate parameters. Results show that the parameters related to the effective soil porosity were highly sensitive to hydrological modeling. N balance was largely controlled by soil denitrification processes. P balance was influenced by the sedimentation rate and production/decay of P in rivers and lakes. The model reproduced the temporal and spatial variations of discharge and TN/TP relatively well in both calibration (2006-2008) and validation (2009-2010) periods. Among the obtained data, the lowest Nash-Suttclife efficiency of discharge, daily TN load, and daily TP load were 0.74, 0.51, and 0.54, respectively. The seasonal variations of daily TN concentrations in the entire simulation period were insufficient, indicated that crop rotation changed the timing and amount of N output. Monthly TN and TP simulation yields revealed that nutrient outputs were abundant in summer in terms of the corresponding discharge. The area-weighted TN and TP load annual yields in five years showed that nutrient loads were extremely high along Hong and Ru rivers, especially in agricultural lands.

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