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  • 51.
    Algesten, Grete
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Wikner, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Sobek, Sobek
    Department of Limnology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden .
    Tranvik, Lars T.
    Department of Limnology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden .
    Jansson, Mats
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Seasonal variation of CO2 saturation in the Gulf of Bothnia: Indications of marine net heterotrophy2004In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 18, p. 4021-4028Article in journal (Refereed)
    Abstract [en]

    Seasonal variation of pCO2 and primary and bacterioplankton production were measured in the Gulf of Bothnia during an annual cycle. Surface water was supersaturated with CO2 on an annual basis, indicating net heterotrophy and a source of CO2 to the atmosphere. However, the Gulf of Bothnia oscillated between being a sink and a source of CO2 over the studied period, largely decided by temporal variation in bacterial respiration (BR) and primary production (PP) in the water column above the pycnocline. The calculated annual respiration-production balance (BR-PP) was very similar to the estimated CO2 emission from the Gulf of Bothnia, which indicates that these processes were major determinants of the exchange of CO2 between water and atmosphere. The southern basin (the Bothnian Sea) had a lower net release of CO2 to the atmosphere than the northern Bothnian Bay (7.1 and 9.7 mmol C m−2 d−1, respectively), due to higher primary production, which to a larger extent balanced respiration in this basin.

  • 52.
    Algotsson, Josefina
    et al.
    SMHI, Core Services.
    Edman, Moa
    SMHI, Research Department, Oceanography.
    Förslag till statusklassning av parameter 9.5 Sötvatteninflöde och vattenutbyte i kustvatten och vatten i övergångszon: En jämförelse mellan Kustzonsmodellens naturliga och normala uppsättning2019Report (Other academic)
    Abstract [en]

    Around half of Sweden's electricity generation consists of hydropower, which is produced in about 2000 power plants. The largest drainage of water from land takes place during the spring and the water is stored in reservoirs for electricity production during the winter. This change in the natural runoff has major effects on the aquatic ecosystems and is considered to be one of the biggest environmental challenges for Swedish waterways and lakes.There is currently no guidance for status classification of hydromorphological parameters in coastal waters according to the Water Framework Directive. SMHI was commissioned by the water authorities to produce a proposal for class boundaries and classification for parameter 9.5 Freshwater inflow and water exchange in coastal water and water in transition zone in accordance with the regulations stated by the Swedish Agency for Marine and Water Management in the document HVMFS 2013:19. The hydrological model S-HYPE and the oceanographic Coastal Zone Model were used to study the changes in fresh water supply as well as fresh water content, salinity and water age of the surface water caused by regulation of water flow on land.In general, the regulation of water flow on land has led to an increase in the fresh water content by 2% along the Norrlands coast and a corresponding decrease in the fresh water content on the west coast. Typically, the regulation of water on land leads to a lower freshwater supply to the coast during spring and summer and a higher freshwater supply to the coast in the autumn and winter compared to a scenario with a natural land runoff.The natural background variation, as defined by ± 2 MAD (Median Absolute Deviation), and the Maximum Absolute Deviation, MAA, were used to construct 5 status classes.

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  • 53.
    Algotsson, Josefina
    et al.
    SMHI, Core Services.
    Van Der Stelt, Frank
    SMHI, Professional Services.
    Abdoush, Diala
    SMHI, Core Services.
    Swedish coastal water bodies on Wikidata Combining WFD data with Wikidata2019Report (Other academic)
    Abstract [en]

    In accordance with the Water Framework Directive, the water district authorities report environmental information on Sweden’s surface water bodies to the EU.Under the government commission Smartare miljöinformation to the Swedish Environmental Protection Agency, Naturvårdsverket, the initiative was taken to adopt the reported environmental information on Sweden’s coastal water bodies to Wikidata and Wikipedia. SMHI has led the initiative with support from Wikimedia Sweden, the South Baltic Sea Water District Authority, the county administrative board of Jönköping and Wikimedia volunteers.The aim of this project has been to make the environmental information about Sweden’s coastal water bodies more accessible to the public, to disseminate knowledge about status classification and create conditions for increasing environmental awareness among the public. The project has resulted in:• 653 new coastal water bodies are described on Wikidata.• Wikipedia articles on water management in Sweden, coastal water bodies and the SVAR database have been created.• A template for infoboxes on Wikipedia has been developed and can automatically retrieve and display the status classification of coastal water bodies.• The template for infoboxes on coastal water bodies is used in articles on coastal waters on Wikipedia.• The license for the SVAR database is set to CC0, which facilitates the use of the information and opens the possibility of using it in more ways than before.

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  • 54. Ali, A Md
    et al.
    Di Baldassarre, G
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Solomatine, Dimitri P
    Testing different cross-section spacing in 1D hydraulic modelling: A case study on Johor River, Malaysia2014In: Hydrological Sciences Journal, no just-acceptedArticle in journal (Refereed)
  • 55. Ali, Genevieve
    et al.
    Tetzlaff, Doerthe
    McDonnell, Jeffrey J.
    Soulsby, Chris
    Carey, Sean
    Laudon, Hjalmar
    McGuire, Kevin
    Buttle, Jim
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Shanley, Jamie
    Comparison of threshold hydrologic response across northern catchments2015In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, no 16, p. 3575-3591Article in journal (Refereed)
    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.

  • 56. Ali, S.
    et al.
    Shekhar, S.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Verma, G.
    Chandrasekhar, T.
    Chandrashekhar, A. K.
    Elevated fluoride in groundwater of Siwani Block, Western Haryana, India: A potential concern for sustainable water supplies for drinking and irrigation2018In: Groundwater for Sustainable Development, ISSN 2352-801X, Vol. 7, p. 410-420Article in journal (Refereed)
    Abstract [en]

    Groundwater pollution is a serious health concern in north-western India. In this study, we have reported very high concentration of fluoride i.e. 18.5 and 16.6 mg/l from Sainiwas locality in Siwani block of Bhiwani district, Haryana, India. The values are much higher than the permissible limit set by WHO and BIS. The evapotranspiration in the area leads to Ca2+ precipitation, which allows an increase in F- content in the groundwater. In addition, the replacement of hydroxyl of secondary clay mineral under alkaline condition is responsible for release of F-. In absence of alternative source, the fluoride polluted groundwater in some of these localities is also used for drinking. Further, the suitability of groundwater for irrigation is also evaluated by various parameters such as Sodium Adsorption Ratio (SAR), Sodium Percentage (Na%), Kelly's Ratio (KR), Magnesium Hazard (MH) and Residual Sodium Carbonate (RSC). It emerges out that in a few localities, groundwater is not suitable for irrigation and with respect to Magnesium Hazard (MH) almost all samples are unsuitable for irrigation. This article highlights groundwater quality of Siwani block in Haryana and proposes for immediate remedial measures. 

  • 57.
    Allesson, Lina
    et al.
    Univ Oslo, Dept Biosci, Oslo, Norway..
    Koehler, Birgit
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Thrane, Jan-Erik
    Norwegian Inst Water Res, Oslo, Norway..
    Andersen, Tom
    Univ Oslo, Dept Biosci, Oslo, Norway..
    Hessen, Dag O.
    Univ Oslo, Dept Biosci, Oslo, Norway..
    The role of photomineralization for CO2 emissions in boreal lakes along a gradient of dissolved organic matter2021In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 66, no 1, p. 158-170Article in journal (Refereed)
    Abstract [en]

    Many boreal lakes are experiencing an increase in concentrations of terrestrially derived dissolved organic matter (DOM)-a process commonly labeled "browning." Browning affects microbial and photochemical mineralization of DOM, and causes increased light attenuation and hence reduced photosynthesis. Consequently, browning regulates lake heterotrophy and net CO2-efflux to the atmosphere. Climate and environmental change makes ecological forecasting and global carbon cycle modeling increasingly important. A proper understanding of the magnitude and relative contribution from CO2-generating processes for lakes ranging in dissolve organic carbon (DOC) concentrations is therefore crucial for constraining models and forecasts. Here, we aim to study the relative contribution of photomineralization to total CO(2)production in 70 Scandinavian lakes along an ecosystem gradient of DOC concentration. We combined spectral data from the lakes with regression estimates between optical parameters and wavelength specific photochemical reactivity to estimate rates of photochemical DOC mineralization. Further, we estimated total in-lake CO2-production and efflux from lake chemical and physical data. Photochemical mineralization corresponded on average to 9% +/- 1% of the total CO2-evasion, with the highest contribution in clear lakes. The calculated relative contribution of photochemical mineralization to total in-lake CO2-production was about 3% +/- 0.2% in all lakes. Although lakes differed substantially in color, depth-integrated photomineralization estimates were similar in all lakes, regardless of DOC concentrations. DOC concentrations were positively related to CO2-efflux and total in-lake CO2-production but negatively related to primary production. We conclude that enhanced rates of photochemical mineralization will be a minor contributor to increased heterotrophy under increased browning.

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  • 58.
    Al-Maliki, Laheab A
    et al.
    Department of Regional Planning, Faculty of Physical Planning, University of Kufa, Najaf, Iraq.
    Al-Mamoori, Sohaib K
    Department of Environmental Planning, Faculty of Physical Planning, University of Kufa, Najaf, Iraq.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    El-Tawel, Khaled
    Lebanese University, Faculty of Engineering, Beirut, Lebanon.
    Comair, Fadi G.
    President of the UNESCO IHP Council, Beirut, Lebanon.
    Climate change impact on water resources of Iraq (a review of literature)2022In: Water Resources in Iraq: Perspectives and Prognosis (ICWRPP 2022), Institute of Physics (IOP), 2022, article id 012025Conference paper (Refereed)
    Abstract [en]

    Maintaining natural processes and supporting social and economic growth depend heavily on water supplies. However, Future climate is predicted to bring higher temperatures, which will increase evapotranspiration; lower precipitation totals; and changes in the seasonal pattern of precipitation. Iraq is more vulnerable to climate change than other nations due to the underdeveloped and fragile water management systems there, as well as the country's desert and warmer environment and increasing sensitivity to extreme weather events. The present work aims to analyse the literature dealing with climate change's effects on water resources in Iraq. The Scopus database was searched using the keywords (Iraq, models of climate change, and water resources). Most models study the effect of high temperatures and evaporation on water resources using different tools, the most important of which are SWAT, LARS-WG, and HEC-HM. The analysis of previous studies shows that the results of all the literature concordant that Iraq is on the verge of severe water scarcity due to high temperatures and the resulting decrease in rainfall, increase in evaporation, decrease in vegetation cover and increase in desertification.

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  • 59.
    Al-Maliki, Laheab Abbas
    et al.
    Department of Regional Planning, Faculty of Physical Planning, University of Kufa, Najaf, Iraq.
    Al-Mamoori, Sohaib Kareem
    Department of Environmental Planning, Faculty of Physical Planning, University of Kufa, Najaf, Iraq.
    El-Tawil, Khaled
    Faculty of Engineering, Lebanese University, Beirut, Lebanon.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Comair, Fadi G.
    Intergovernmental Hydrological Programme (IHP), UNESCO IHP Council, Beirut, Lebanon.
    Eslamian, Saeid
    Department of Water Science and Engineering, College of Agriculture, Isfahan University of Technology, Isfahan, Iran; Excellence Center of Risk Management and Natural Hazards, Isfahan University of Technology, Isfahan, Iran.
    Optimization of Reservoir Operation for Irrigation2023In: Handbook of Irrigation Hydrology and Management: Irrigation Fundamentals / [ed] Saeid Eslamian, Faezeh Eslamian, Taylor & Francis, 2023, 1, p. 347-360Chapter in book (Other academic)
    Abstract [en]

    Water used for irrigation is accounted for 70%–80% of the total water used worldwide. Thus, efficient management of the water resources is the key point to the sustainable water use. The difference between the inflow and water needs is one of the reasons for constructing a reservoir. Many studies were conducted regarding optimizing reservoir operation for irrigation to achieve the desired goals and objectives of the reservoir system. Significant and increasing scientific efforts were conducted to develop and implement the optimization techniques to operate the reservoirs for irrigation. All of the literature aims to minimize the gap between the water release policy and water demands determine release and transfer decisions that maximize water management objectives, and they all confirmed that using mathematical models to optimize and simulate the reservoir operation can enhance the performance of the reservoirs, as well as improve the crop yield. It is expected that this direction continues to evolve, and hopefully, the results of these models would encourage water managers to put them into practice to upgrade the agricultural sector.

  • 60.
    Almasalmeh, O
    et al.
    Technische Universität Berlin Campus El-Gouna, Egypt.
    Saleh, Ahmed Adel
    National Water Research Center, Egypt.
    Mourad, Khaldoon A.
    The Centre for Sustainable Visions, Sweden.
    Soil erosion and sediment transport modelling using hydrological models and remote sensing techniques in Wadi Billi, Egypt2021In: Modeling Earth Systems and Environment, ISSN 2363-6203, E-ISSN 2363-6211, Vol. 8, no 1, p. 1215-1226Article in journal (Refereed)
    Abstract [en]

    Modelling soil erosion and sediment transport are vital to assess the impact of the flash floods. However, limited research works have studied sediment transport, especially in Egypt. This paper employs the HEC-HMS lumped hydrological model to predict the sediment load due to the flood event of 9th March 2014 in Wadi Billi, Egypt. The Modified USLE model has been used to calculate the total upland erosion, while Laursen-Copeland has been used to simulate load streams' sediment transport potential. The Normalized Difference Vegetation Index (NDVI) has been applied over Landsat 8 image captured on 20th February 2014 using ArcMap 10.5 to determine the vegetation cover based on its spectral footprint. The resulted sedigraph showed accumulation of more than five thousand tons of sediments at the Wadi's outlet. The results are crucial to design a suitable stormwater management system to protect the downstream urban area and to use flood water for groundwater recharge.

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  • 61.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Edman, Moa
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Modelling nutrient retention in the coastal zone of an eutrophic sea2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 20, p. 5753-5769Article in journal (Refereed)
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  • 62.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Hordoir, Robinson
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Hall, Per O. J.
    Transport of fresh and resuspended particulate organic material in the Baltic Sea - a model study2011In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 87, no 1, p. 1-12Article in journal (Refereed)
    Abstract [en]

    A fully coupled high-resolution 3-dimensional biogeochemical-physical ocean model including an empirical wave model was used to investigate the long-term average (1970-2007) distributions and transports of resuspended matter and other types of suspended organic matter in the Baltic Sea. Modelled bottom types were compared to observations and the results showed that the model successfully managed to capture the horizontal, as well as the vertical, distribution of the different bottom types: accumulation, transport and erosion bottoms. The model also captured well the nutrient element contents in the sediments. On average the largest contribution of resuspended organic carbon to the transport of total organic carbon is found at erosion and transport bottoms. Although the relative transport of resuspended organic carbon at deeper accumulation bottoms in general is low (< 10% of total), the central parts of the sub-basins act on average as sinks that import organic matter while the more shallow areas and the coastal regions acts as sources of organic carbon in the water column. This indicates that the particulate organic matter produced in erosion and transport areas might be kept in suspension long enough to be transported and settle in less energetic areas, i.e. on accumulation bottoms. (C) 2011 Elsevier B.V. All rights reserved.

  • 63.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Kuznetsov, Ivan
    Hall, Per O. J.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    A new approach to model oxygen dependent benthic phosphate fluxes in the Baltic Sea2015In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 144, p. 127-141Article in journal (Refereed)
    Abstract [en]

    The new approach to model the oxygen dependent phosphate release by implementing formulations of the oxygen penetration depths (OPD) and mineral bound inorganic phosphorus pools to the Swedish Coastal and Ocean Biogeochemical model (SCOBI) is described. The phosphorus dynamics and the oxygen concentrations in the Baltic proper sediment are studied during the period 1980-2008 using SCOBI coupled to the 3D-Rossby Centre Ocean model. Model data are compared to observations from monitoring stations and experiments. The impact from oxygen consumption on the determination of the OPD is found to be largest in the coastal zones where also the largest OPD are found. In the deep water the low oxygen concentrations mainly determine the OPD. Highest modelled release rate of phosphate from the sediment is about 59 x 10(3) t P year(-1) and is found on anoxic sediment at depths between 60-150 m, corresponding to 17% of the Baltic proper total area. The deposition of organic and inorganic phosphorus on sediments with oxic bottom water is larger than the release of phosphorus, about 43 x 10(3) t P year(-1). For anoxic bottoms the release of total phosphorus during the investigated period is larger than the deposition, about 19 x 10(3) t P year(-1). In total the net Baltic proper sediment sink is about 23.7 x 10(3) t P year(-1). The estimated phosphorus sink efficiency of the entire Baltic Sea is on average about 83% during the period. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

  • 64.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Skogen, Morten D.
    A North Sea and Baltic Sea Model Ensemble Eutrophication Assessment2010In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 39, no 1, p. 59-69Article in journal (Refereed)
    Abstract [en]

    A method to combine observations and an ensemble of ecological models is suggested to produce a eutrophication assessment. Using threshold values and methodology from the Oslo and Paris Commissions (OSPAR) and the Helsinki Commission (HELCOM), four models are combined to assess eutrophication for the Baltic and North Seas for the year 2006. The assessment indicates that the entire southeastern part of the North Sea, the Kattegat, the Danish Straits, the Gulf of Finland, and the Gulf of Riga as well as parts of the Arkona Basin, the Bornholm Basin, and the Baltic proper may be classified as problem areas. The Bothnian Bay and parts of the Baltic proper, the Bornholm Basin, and the Arkona Basin are classified as potential problem areas. This method is a useful tool for the classification of eutrophication; however, the results depend on the threshold values, and further work is needed within both OSPAR and HELCOM to harmonize these values.

  • 65.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Skogen, Morten
    Sehested Hansen, Ian
    DHI Water and Environments.
    Stipa, Tapani
    University of Helsinki.
    Niiranen, Susa
    Stockholm University.
    The Year 2006 An Environmental Status report of the North Sea, Skagerrak, Kattegat and the Baltic Sea2007In: BANSAI- The Baltic and North Sea marine environmental modelling Asessment Initaiative / [ed] the Nordic Council of Ministers’ Sea and Air Group, 2007Conference paper (Other academic)
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  • 66.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Wåhlstrom, Irene
    SMHI, Research Department, Oceanography.
    Hansson, Martin
    SMHI, Core Services.
    Vali, Germo
    Eilola, Kari
    SMHI, Core Services.
    Andersson, Pia
    SMHI, Core Services.
    Viktorsson, Lena
    SMHI, Core Services.
    Hieronymus, Magnus
    SMHI, Research Department, Oceanography.
    Arneborg, Lars
    SMHI, Research Department, Oceanography.
    A Regime Shift Toward a More Anoxic Environment in a Eutrophic Sea in Northern Europe2021In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 8, article id 799936Article in journal (Refereed)
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    A Regime Shift Toward a More Anoxic Environment in a Eutrophic Sea in Northern Europe
  • 67.
    Al-Mutawqi, Kareem Ghafel
    et al.
    University of Al-Qadisiyah, College of Science, Iraq.
    Ewaid, Salam Hussein
    Technical Institute of Shatra, Southern Technical University, Basra, Iraq.
    Abed, Salwan Ali
    University of Al-Qadisiyah, College of Science, Iraq.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Salim, Mudhafar A.
    Arab Regional Center for World Heritage, Manama, Bahrain.
    Kadhim, Ameer J.
    Ministry of Water Resources, General Commission of Groundwater, Baghdad, Iraq.
    Hydrogeochemical processes and evaluation of groundwater in Al-Salman area - Iraqi Southern Desert2021In: Journal of Water and Land Development, ISSN 1429-7426, Vol. 50, p. 220-228Article in journal (Refereed)
    Abstract [en]

    A field survey has been conducted for the study area using the Global Positioning System (GPS) and geological and geomorphological maps of the area. The study area is one of the important areas in Iraq characterized by scarce water resources. The purpose of the study is to determine the hydro-chemical processes and their relationship to groundwater quality carried out in the southwestern desert region of Iraq, where the region lacks extensive studies of water resources. Twenty-eight groundwater samples were collected from wells distributed between the eastern borders of Saudi Arabia and the West Bank of the Euphrates River. For the purpose of hydrogeochemical analyses, the Fetter method was used to collect and examine samples. A large part of the recharge area is located in Saudi Arabia, where the groundwater bearing aquifer represented by the Dammam formation extends to Iraq and Saudi Arabian International borders. The analysis determined the order of cations (Na+ > Ca2+ > Mg2+ > K+) and anions (Cl- > SO42- > HCO3-). High values of the variation coefficient (CV) correspond to the concentration of potassium, sodium and chloride ions (CV: 68.7, 64.7 and 64 respectively). To identify the hydrochemical water facies, the Piper diagram was used. It was found that 53% of the water samples belong to the Na-Cl type and 40% are of the Ca-Mg-Cl type, while the rest of the samples are the Ca-Cl type. To identify geochemical processes, it was found that ion exchange processes via chloroalkaline indices 1 and 2 are prevalent between Ca2+, Mg2+ in the groundwater and Na+, K+ in water bearing rocks. To learn more about the processes that led to the concentration of certain ions, such as sodium, it was found that they tend to be of silicate minerals related to surface runoff of water in recharge areas and carbonic rocks. It was also found that rock/soil-groundwater interaction and evaporation processes were the formal processes in the saturated zone and evaporation in the unsaturated zone are prevalent processes of groundwater ion concentration.

  • 68.
    Althoff, Daniel
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Global patterns in water flux partitioning: Irrigated and rainfed agriculture drives asymmetrical flux to vegetation over runoff2023In: One Earth, ISSN 2590-3330, E-ISSN 2590-3322, Vol. 6, no 9, p. 1246-1257Article in journal (Refereed)
    Abstract [en]

    The partitioning of precipitation water input on land between green (evapotranspiration) and blue (runoff) water fluxes distributes the annually renewable freshwater resource among sectors and ecosystems. The patterns and main drivers of this partitioning are not fully understood around the global land area. We decipher the worldwide patterns and key determinants of this water flux partitioning and investigate its predictability based on a global machine learning model. Available data for 3,614 hydrological catchments and model application to the global land area agree in showing mostly larger green than blue water flux. Possible expansion/intensification of irrigated and/or rainfed agriculture to feed a growing human population, along with climate warming, will tend to increase this flux partitioning asymmetry, jeopardizing blue water security. The developed machine learning model presents a promising predictive tool for future blue and green water availability under various forthcoming climate and land-use change scenarios around the world.

  • 69.
    Alvarez, Elena Alabarces
    et al.
    SMHI, Research Department, Oceanography.
    Klemm, Kerstin
    Hoppenrath, Mona
    Cembella, Allan
    John, Uwe
    Karlson, Bengt
    SMHI, Research Department, Oceanography.
    Temporal and spatial distribution of epibenthic dinoflagellates in the Kattegat-Skagerrak, NE Atlantic-Focus on Prorocentrum lima and Coolia monotis2022In: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 118, article id 102318Article in journal (Refereed)
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    Temporal and spatial distribution of epibenthic dinoflagellates in the Kattegat-Skagerrak, NE Atlantic-Focus on Prorocentrum lima and Coolia monotis
  • 70. Al-Yaarubi, A. H.
    et al.
    Pain, C. C.
    Grattoni, C. A.
    Zimmerman, Robert W.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Navier-Stokes Simulations of Fluid Flow Through a Rock Fracture2013In: Dynamic Fluids and Transport Through in Fractured Rock, American Geophysical Union (AGU), 2013, p. 55-64Chapter in book (Other academic)
    Abstract [en]

    A surface profilometer was used to measure fracture profiles every 10 microns over the surfaces of a replica of a fracture in a red Permian sandstone, to within an accuracy of a few microns. These surface data were used as input to two finite element codes that solve the Navier-Stokes equations and the Reynolds equation, respectively. Numerical simulations of flow through these measured aperture fields were carried out at different values of the mean aperture, corresponding to different values of the relative roughness. Flow experiments were also conducted in casts of two regions of the fracture. At low Reynolds numbers, the Navier-Stokes simulations yielded transmissivities for the two fracture regions that were closer to the experimental values than were the values predicted by the lubrication model. In general, the lubrication model overestimated the transmissivity by an amount that varied as a function of the relative roughness, defined as the standard deviation of the aperture divided by the mean aperture. The initial deviations from linearity, for Reynolds numbers in the range 1-10, were consistent with the "weak inertia" model developed by Mei and Auriault for porous media, and with the results obtained computationally by Skjetne et al in 1999 on a two-dimensional self-affine fracture. In the regime 10 < Re < 40, both the computed and measured transmissivities could be fit very well to a Forchheimer-type equation, in which the additional pressure drop varies quadratically with the Reynolds number.

  • 71. Amaguchi, H.
    et al.
    Kawamura, A.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Takasaki, T.
    Development and testing of a distributed urban storm runoff event model with a vector-based catchment delineation2012In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 420, p. 205-215Article in journal (Refereed)
    Abstract [en]

    The recent advances in GIS technology as well as data availability open up new possibilities concerning urban storm runoff modeling. In this paper, a vector-based distributed storm event runoff model - the Tokyo Storm Runoff (TSR) model - is developed and tested for urban runoff analysis using two historical storm events. The set-up of this model is based on urban landscape GIS delineation that faithfully describes the complicated urban land use features in detail. The flow between single spatial elements is based on established hydraulic and hydrological models with equations that describe all aspects of storm runoff generation in an urban environment. The model was set up and evaluated for the small urban lower Ekota catchment in Tokyo Metropolis, Japan. No calibration or tuning was performed, but the general model formulation was used with standard parameter values obtained from the literature. The runoff response to two storm events were simulated; one minor event resulting only in a small-scale flood wave and one major event which inundated parts of the catchment. For both events, the simulated water levels closely reproduced the observed ones. For the major event, also the reported inundation area was well described by the model. It was also demonstrated how the model can be used to evaluate the flow conditions in specific components of the urban hydrological system, which facilitates e.g. evaluation of flood-preventive measures. (C) 2011 Elsevier B.V. All rights reserved.

  • 72.
    Ambjörn, Cecilia
    SMHI, Professional Services.
    Förstudie av ett nordiskt modellsystem för kemikaliespridning i vatten1988Report (Other academic)
    Abstract [sv]

    SMHI har fått i uppdrag att studera ett befintligt system för spridning av kemikalier i vatten. Studierna utförs med syfte att skapa ett för nordiska behov användbart prognossystem vid olyckstillbud.

    Främst studeras U. S. Coast Guards beräkningssystem HACS, Hazard Assessment Computer System. Det är uppbyggt utifrån behov av att veta huruvida vattenintag i floder behöver stängas vid ett giftutsläpp, fiskodlingar skyddas och när koncentrationen nått låga nivåer i hela området.

    HACS-modellerna för vatten är ingående analyserade. De som nu finns i ett fungerande prognossystem har studerats, men även nyutvecklade modeller som inte är anpassade för det befintliga prognossystemet har betraktats .Det kanadensiska systemet TIPS har studerats något, liksom en sammanställning över EG-ländernas modeller.

    HACS-systemet i sin nuvarande form är inte tillämpbart i öppet vatten eller i kust- och skärgårdsområden. Systemet är främst utvecklat för floder och kan därför inte användas i havet där dynamiken är helt annorlunda .Ett spridningsförlopp i en flod använder sig av konstant ström i tid och rum, konstant vind, begränsande väggar på sidorna, sötvatten och ganska lätt kontrollerbara processer. I havet är dynamiken betydligt mera komplicerad och komplex. Vågor , vädersystem, strömmar som varierar kraftigt mellan olika djup, horisontella strömvariationer som ändras inom några 100-tals meter, tre-dimensionella virvelsystem av olika storlekar, varierande bottendjup, tidsvariationer som sker inom några timmar, olika densiteter på skilda djup är några av de mest grundläggande skillnaderna . Enskilda förlopp inom HACS kan ändå användas, såsom tex beräkningen av ett flytande ämnes utspridning på vattenytan de första timmarna. Teoretiska delar kan tas ur programmen och manualerna och användas i nya system. Särskilt gäller den här möjligheten de nyare programmen inom HACS-systemet , där teorin är mera långtgående och omfattande.

    Citat U. S . Coast Guard. "HACS kan vara ett extremt kraftfullt verktyg, när det handhas av en specialist, som kan formulera ett problem till HACS korrekt och därefter tolka de erhållna resultaten. Samtidigt kan systemet oavsiktligt användas helt felaktigt om det appliceras på situationer som ej var menade för tillämpning. Det finns ingen automatisk metod att hindra felanvändning, utan användaren måste vara rimligt insatt i metodiken bakom modellerna ."

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  • 73.
    Ambjörn, Cecilia
    SMHI, Professional Services.
    Isproppsförebyggande muddring och dess inverkan på strömmarna i Torneälven1992Report (Other academic)
    Abstract [sv]

    Bakgrund

    Muddring i Torneälvens mynningsområde studeras, som en möjlighet att minska risken för isproppsbildning och därmed risken för översvämning. Effekterna för strömmarna vid muddrad farled och en bruten isränna beräknas med en numerisk datormodell. Även effekterna av en muddrad grop i mynningen simuleras med modellen. Bedömning av förändrade sedimentationsmönster utförs liksom ändrad isproppsrisk.

    Endast mycket höga flöden betraktas, dvs 2 500 m3 /s och 3100 m3/s.

    Vid simuleringarna väljs en utbredning av havsisen, som man av erfarenhet vet förekommer då ispropp med översvämning inträffar. Likaså får isens tjocklek ett representativt värde, 80 cm. Olika vattenstånd i havet betraktas även.

    Beräkningsmodellen tar inte hänsyn till att vattnet tar en alternativ väg vid översvämning eller till effekterna av en ispropp. Det innebär att hastigheterna under isen blir för höga eftersom vattenmassor tvingas in under isen, som annars skulle svämma över landområden. Med dessa förenklingar erhålls en god uppfattning av de typiska effekter på strömmarna som de olika muddringsalternativen ger upphov till. Beräkningarna av strömmarna visar att hastigheterna i mynningen och huvudfåran är mycket höga; 2 - 4 m/ s.

    Strömförhållanden

    Muddrad farled

    Muddrad farled och bruten ränna medför att en betydligt större del av vattnet går genom rännan eftersom tvärsnittsytan ökar. Det medför att hastigheterna i hela övriga mynningsområdet minskar. På de grunda områdena på ömse sidor om farleden och norr om Selkäkari sker en kraftig minskning av hastigheterna. Vid lägre flöde och högre havsvattenstånd är den procentuella förändringen mindre.

    Muddrad grop

    En muddrad grop i mynningsområdet och samtidigt istäckt i havet innebär att i och omkring gropen erhålls lägre hastigheter i proportion till den ökade tvärsnittsytan.

    Ej islagd period

    Vid icke islagd tid medför den muddrade farleden att vattnet styrs till den muddrade rännan. Det blir något lägre hastigheter; 20 - 25 %, norr om Selkäkari. Hastigheterna på de grundare områdena på ömse sidor om rännan minskar något. Vid muddrad grop sker endast en hastighetssänkning vid gropen.

    Sedimentationsbedömningar

    Torneälvens mynningsområde domineras av sediment med mycket blandad kornstorlek, från silat till grus, och litet organiskt innehåll. Detta visar att mycket lite deposition och erosion förekommer (gäller relativt öppna vatten, inte grunda kanaler och vikar), De mindre mängder av grövre sediment (icke suspenderade) som älven för med sig deponeras strax efter att den mynnat, i beräkningsområdets norra del. Merparten av de sediment som älven för med sig deponeras söder om beräkningsområdet - i skärgården och havet därutanför.

    Muddrad ränna

    Detta muddringsalternativ leder till högre strömhastigheter än för nuvarande förhållanden i huvudströmfåran. Förhöjningen är dock så liten att det inte kommer leda till några erosionsproblem. Den lite starkare strömmen skulle hjälpa till att hålla rännan öppen (förutsatt att rännan ligger i linje med strömriktningen). Underhållsmuddring går dock inte att utesluta, som mest ungefär var 5 - 10 år.

    De minskade strömhastigheterna, i {åran norr om Selkäkari och Kraaseli skulle ha kunnat leda till depositionsproblem om det inte vore för att området är så grunt. Redan i dagens läge hålls sedimenten delvis i suspension av de vattenrörelser som vågor orsakar. Viss deposition, eller ökning av deposition, får man dock räkna med innanför Selkäkari - i värsta fall uppåt en centimeter per år.

    En följd, om än knappt märkbar vad gäller sedimentation, är att mer vatten följer huvudströmfåran om man muddrar en ränna, och då kommer mer suspenderat material föras ut i skärgården än tidigare.

    Lokal muddring

    Eftersom strömmarna bara förändras där den lokala muddringen eventuellt sker, kommer med stor sannolikhet ingen förändrad sedimentation ske i resten av mynningsområdet. De minskade strömhastigheterna i det lokala muddringsområdet kan tänkas leda till en ökad deposition av grövre sediment (sand/ grus). Det mesta av detta grövre material kommer dock liksom i nuvarande fall att fällas ut på bottnarna söder och sydväst därom, där strömhastigheterna avtar ordentligt. Den lokala muddringen sker i anslutning till två redan existerande "djuphål" (en och ett par meter djupare än omgivningen) som tydligen inte visar tendenser att fyllas igen. På grund av att sedimentationstakten på platsen är låg/ingen, att strömmarna trots muddring ändå kommer vara relativt höga, att strömmarna inte avtar ordentligt förrän söder om den tänkta lokala muddringen, och eftersom det redan finns fördjupningar, är det sannolikt att det muddrade hålet inte fylls i alls, ·. eller i långsam takt. Som mest kan underhållsmuddring uppskattningsvis behöva utföras var tionde år.

    lsproppsbedömning

    Vid muddrad farled och bruten isränna kan risk finnas för ispropp i rännan, speciellt där den byter riktning. Ispropp kan även bildas i isrännans öppning mot floden genom att isflak fastnar på de grundare områdena och successivt böjer av in mot rännan och sedan täpper igen denna. Muddrad grop ger lägre strömhastigheter i gropen vilket medför att isens vertikala utsträckning går något långsammare (på grund av lägre tryck) och den horisontella utbredningen ökar något. Båda muddringsförslagen bidrar var för sig till minskad risk för isproppsbildning.

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  • 74.
    Ambjörn, Cecilia
    SMHI, Professional Services.
    Oceanografiska förhållanden i Brofjorden i samband med kylvattenutsläpp i Trommekilen1989Report (Other academic)
    Abstract [sv]

    Vattenfall har för avsikt att lokalisera en restoljeförgasningsanläggning intill Scanraff i Brofjorden. SMHI har därför fått i uppdrag att utföra en utredning avseende de oceanografiska förhållandena i området.

    Anläggningen behöver kylvatten som tas in på cirka 15 meters djup i Trommekilen via en tub om 1.2 meter i diameter. Se kartan i figur 1. Därefter planeras det uppvärmda vattnet att ledas ut som ytvatten via en muddrad ränna. Kylvattenmängden är cirka 7.5 m3/s och temperaturstegringen genom processen är cirka 10°c .

    Studien behandlar dessutom ett ytintag i Trommekilen och utsläpp i Brofjordens mynning med hastigheten 1.5 m/s.

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  • 75.
    Ambjörn, Cecilia
    SMHI, Professional Services.
    Oceanografiska förhållanden utanför Vendelsöfjorden i samband med kylvattenutsläpp1990Report (Other academic)
    Abstract [sv]

    Vattenfall planerar ett naturgaseldat kraftverk utanför Vendelsöfjorden. Det är tänkt att anläggningen ska producera maximalt 700 MW och släppa ut 10 m3 kylvatten per sekund, som är uppvärmt 10 °c. Kylvattnet planeras att tas in nära bottnen och släppas ut i ytan.

    Strömmarna, i området mellan Vendelsöfjorden och den öppna kusten, är riktade in mot Vendelsöfjorden under 10 procent av tiden. En inåtgående ström, med en samtidig 1-2 km bred utåtgående ström intill kusten, råder under 30 procent av tiden. Vid resterande tillfällen är strömmen varierande eller sydgående.

    Den vertikala densitetsskiktningen är dominerad av salthaltens ökning från ytan och neråt. Skiktningen kan vara mycket kraftig med 14 promilles salthalt i ytan och 34 promille vid botten. Samma salthalt kan också förekomma i hela vattenmassan, då ligger värdena ofta mellan 18 och 21 promille.

    På sommaren förstärks densitetsskiktningen av att ytvattnet värms upp snabbare än bottenvattnet. Samma temperatur kan även råda ända ner till bottnen, eftersom här är grunt. Temperaturförändringen finns då på större djup, längre ut från kusten. Under november - mars kan det vara några grader varmare på 15 meters djup än i ytan.

    Om kylvattnet tas in nära botten på 15-17 meters djup och släpps ut i ytan kommer det att vara tyngre än sin omgivning under stor del av året. Vid de tillfällen när kylvattnet är lättare eller endast obetydligt tyngre än ytvattnet blandas det in i ytan mellan cirka O och 3 m djup, därmed blir den horisontella spridningen effektiv. Avdunstning, vind och vågor gör att övertemperaturen blir lägst vid spridning i ytan. När salthalten vid bottenintaget är hög blir kylvattnet betydligt tyngre än det omgivande ytvattnet. Det sjunker då ner till en nivå ovanför salthaltssprångskiktet, som ligger på 10-15 meters djup. Här ligger kylvattnet relativt koncentrerat, ty den vertikala blandningen är begränsad av vattnets skiktning.

    Kylvattnet från Ringhals kan, så här långt från källan, ha högst 1-2 °c övertemperatur i ett ytnära skikt. Detta kylvatten går norrut cirka 4 gånger av 10. Vid dessa tillfällen har kylvattnet från det planerade kraftverket antingen sjunkit ner i vattenmassorna och lagt sig på 5-10 meters djup eller så ligger det nära ytan. När strömmen går in mot Vendelsöfjorden och därmed mot nordost i hela området, vilket händer 1 gång av 10, ökar den sammanlagda ytan för l0 oc övertemperatur.

    Vid inåtgående ström längre ut och en sydvästgående smalare ström nära kusten, vilket inträffar 3 gånger av 10, kan en viss förstärkt effekt erhållas där kylvattenplymerna möts, sydväst om det planerade läget . Vid cirka hälften av dessa tillfällen ligger kylvattnet från båda kraftverken i ytan. Detta betyder i praktiken 15 procent av tiden.

    Lämpligt läge för kylvattenutsläppet är därför utefter en linje vinkelrätt ut från kusten. Läggs utsläppet nära kusten kan det under 15 % av tiden samverka i ytan med utsläppet från Ringhals. Aktuella övertemperaturer är högst 1-2 °c. Vid en placering cirka 2 km ut från kusten kommer det under 20 % av tiden att bli en förlängning av plymen från Ringhals.

    Avgörande för en snabb utspädning är den hastighet med vilken kylvattnet förs ut i havet. Lämpliga hastigheter kan vara 1 . 0-2 . 0 m/s.

    Vid sydgående ström samtidigt som kylvattnet från det planerade läget lägger sig i ytan, kan en mindre temperaturförhöjning erhållas vid intaget för Ringhals kylvatten.

    Kännedomen om vattenutbytet är begränsad. Vid svaga strömmar som skiftar riktning 1 gång per dygn eller oftare sker en viss ansamling av kylvatten i närområdet. Vid ström in mot Vendelsöfjorden kan högst 3-4 graders temperaturhöjning ske på de större djupen inne i fjorden alternativt maximalt 2 graders höjning från ytan till botten i hela fjorden. Ovanstående gäller vid sjunkande kylvatten.

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  • 76.
    Ambjörn, Cecilia
    SMHI, Professional Services.
    Spridning av kylvatten från Öresundsverket1987Report (Other academic)
    Abstract [sv]

    Ett antal olika spridningsförlopp från alternativa kylvattenutsläpp har beräknats. Resultaten ger information om övertemperaturen i ytskiktet och vilka områden som berörs. Utsläpp har studerats från nuvarande läge, här benämnt läge 1 och som ligger 1 km uppströms Sege å, från läge 2 något utanför Sege ås mynning, från läge 3 vid mynningen av kommunens avlopp och läge 4 strax utanför Malmö Hamns planerade utfyllnad, etapp 2 . Volymflödena har varierat mellan 10 och 30 m3/s och övertemperaturen har initialt varit 100c. Fyra olika typiska strömningsmönster har legat till grund för den mer storskaliga transporten av kylvatten. Dessa är nordgående ström(stark och svag) samt sydgående ström(stark och svag). Vid nordgående ström har vind från norr 5 m/s även lagts in i modellberäkningarna för att ge effekterna vid ogynnsamma yttre omständigheter. Vid sydgående ström har vind från väster tagits med. Den planerade utfyllnaden vid Spillepeng är inlagd i alla beräkningarna. Däremot är Malmö Hamns planerade utfyllnad, etapp 2, endast inlagd vid ett av de fyra olika strömningsalternativen.

    Beräkningar har även utförts av möjligheten hålla Oljehamnen isfri liksom beräkningar av initiell avkylning och inblandning av kylvattnet för de aktuella utsläppsalternativen.

    Resultaten visar att Oljehamnen bör kunna hållas isfri vid ett flöde på 15-30 m3/s och utsläppstemperaturen 10 °c. Denna värmemängd bör även kunna smälta ett måttligt tjockt istäcke.  I stora drag erhålls följande resultat för de olika utsläppslägena med sina respektive kylvattenmängder. De olika alternativen grupperar sig inbördes i stort sett i samma ordning oberoende av aktuellt strömningsmönster. Avgörande är istället utsläppsläge och mängd kylvatten. Utsläppsläge 4, (utanför Malmö Hamns planerade utfyllnad) har mindre än hälften så stora ytor med övertemperaturer som är större än 2 °c jämfört med övriga utsläppslägen. Det är därefter två olika lägen som ger störst initialutspädning, dvs minsta ytorna med de högre övertemperaturerna. Dessa är läge 3 med 30 m3/s (vid avloppstubernas mynning) och läge 1 (uppströms i Sege å) med 20 m3/s. Sämst initiell utspädning erhölls för läge 2, (något utanför Sege ås mynning) med 30 m3/s. Övriga alternativ, där det ena är 20 m3/s i läge 1 samtidigt med 10 m3/s i läge 3 och det andra är 30 m3/s i läge 1, grupperar sig mellan de redan nämnda och har något varierande ordning beroende på strömförhållandena.

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  • 77.
    Ambjörn, Cecilia
    SMHI, Professional Services.
    Strömningsteknisk utredning avseende utbyggnad av gipsdeponi i Landskrona1990Report (Other academic)
    Abstract [sv]

    HYDRO SUPRA AB planerar att utvidga sin gipsdeponering utanför Landskrona söderut. SMHI har därför fått i uppdrag att beräkna eventuella förändringar av vattenutbyte och strömmar i norra Lundåkrabukten. Strömförhållandena idag och efter en utbyggnad simuleras med en numerisk tredimensionell hydrodynamisk modell. Beräkningarna stöder sig på strömmätningar i två punkter i det studerade området samt strömförhållandena i centrala Öresund.

    Strömmen mättes under maj månad 1990. Resultaten visar att cirkulationen i Lundåkrabukten drivs av strömningen i centrala Öresund, speciellt gäller det för den långperiodiska strömningen. Tidvattnet har en viss betydelse i bukten och bidrar till relativt täta strömväxlingar. På det grunda området, mindre än I meter, har den lokala vinden stor betydelse för strömmarna. Innanför vågbrottszonen bildas intermittent en restström av de brytande ytvågorna.

    Strömmen mättes under maj månad 1990. Resultaten visar att cirkulationen i Lundåkrabukten drivs av strömningen i centrala Öresund, speciellt gäller det för den långperiodiska strömningen. Tidvattnet har en viss betydelse i bukten och bidrar till relativt täta strömväxlingar. På det grunda området, mindre än I meter, har den lokala vinden stor betydelse för strömmarna. Innanför vågbrottszonen bildas intermittent en restström av de brytande ytvågorna.

    Vattenutbyte

    Vid nordgående ström och nordlig eller sydlig vind påverkas vattenutbytet 1 nordligaste delen relativt litet, det minskar med storleksordningen någon procent. Vid nordgående ström och ostlig vind är förändringen av vattenutbytet något större. Strax öster om utbyggnaden sker en minskning på 50 procent över en bredd av cirka 600 meter. Öster härom sker ingen förändring. När utbytet betraktas i en linje från Gipsön och in mot land rakt österut, kan minskningen uppskattas till maximalt 10 procent. Denna strömsituation förekommer under I O - 20 procent av tiden, vilket innebär att sett över en längre tidsperiod är förändringen I - 2 procent.

    Vid sydgående ström och västlig vind är minskningen i det nordligaste delen av området cirka 10 - 15 procent. Totalt sett är volymerna här små. Vid svaga västvindar blir förändringen mindre. Förändringen är lokal strax öster och sydost om utfyllnaden. Västlig vind förekommer till cirka 40 procent under 1 år. Det ger totalt sett över en längre tidsperiod en minskning i nordligaste delen på 4-6 procent.

    Strömförhållanden

    Strömmen har studerats i närområdet före och efter utbyggnad. En förstoring av området gör att en visuell bedömning kan göras. För alla de fyra olika strömningssimuleringarna gäller att förändringen av strömmarna är obetydlig.

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  • 78.
    Ambjörn, Cecilia
    et al.
    SMHI, Professional Services.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Vatten- och materialtransporter mellan bottniska viken och Östersjön1979Report (Other academic)
    Abstract [en]

    Within the framework of the Swedish-Finnish Joint Cornmitte on the Gulf of Bothnia, investigations have been carried out in the Åland Sea and in the Finnish Archipelago Sea in order to study water exchange and transports of heat and nutrients between the Gulf of Bothnia and the Baltic proper. The work has been a cooperation between the Swedish Meteorological and Hydrological Institute (SMHI) and the Finnish Institute of Marine Research. Measurements have been performed by SMHI during the periods June-December 1973, July-December 1974, August 1975-May 1976 and June- August 1977, most intensively in 1974 and 1977. The following parameters have been measured: current speed and direction, water temperature, salinity, oxyge , total phosphorus and total nitrogen.

    The current patterns in the northern part of the Åland Sea are described .An expansion of the north- south current components into empirical orthogonal functions shows the main characteristics of the current systems. The mean circulation during thermally stratified conditions shows southgoing currents in the upper layer and northgoing in the lower. A simple numerical model shows that the main driving force on the net current, when the vertical stratificationis weak, is the surface slope along the channel. Local acceleration and bottom friction are also important.

    Water transports have been calculated from the current measurements.The water exchange is most probably largest during the autumn. In the surnmer of 1977 measurements were made on both sides of Åland. The net transport was southgoing in the Åland Sea (46-95 km3 month- l to the north and 78-236 to the south) and northgoing in the Archipelago Sea (28-44 km3 • month- l to the north and 14-31 to the south) . Comparing the net exchange between the central Baltic and the Gulf of Bothnia with the volume changes in the latter , determined from water level records , gives a difference that probably depends on the choice of representative areas for the current meters. Calculations of transports of total phosphorus, total nitrogen and heat have also been made.

    English translations of captions to figures and tables are found in appendix 11 (the last pages of this report).

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    Vatten- och materialtransporter mellan bottniska viken och Östersjön
  • 79.
    Ambjörn, Cecilia
    et al.
    SMHI, Professional Services.
    Grafström, Torbjörn
    SMHI.
    Andersson, Jan
    SMHI, Core Services.
    Spridningsberäkningar - Klints Bank1990Report (Other academic)
    Abstract [sv]

    Gotlandsolja AB har uppdragit åt IVL att genomföra en miljökonsekvensutredning med anledning av planerad provborrning efter olja på Klints Bank öster om Gotland. SMHI har fått i uppdrag att genomföra punkt 2 i denna utredning, som berör spridning av ett tänkt oljeutsläpp.

    Ett numeriskt modellarbete ligger till grund för spridningsberäkningarna. Vinduppgifter är framtagna ur klimatstatistik och utgör historiska observationer från olika säsonger.

    Under vinter- och vårsäsongen berörs i majoriteten av fallen Gotlands ost- och sydkust efter 30 dygn eller mindre. I ogynnsamma fall, kraftiga NE-E vindar, når oljan Gotlands kust inom 2 dygn. I enstaka fall berörs också Stockholms skärgård och Öland.

    Sommar och höst, med majoriteten av vindar från sektorn S-NY, påverkas i hög grad Baltiska kusten inom 30 dygn. I ogynnsamma fall kan det ske inom   5 - 6 dygn.

    Under nov-jan är ca var 3:e observerad vindhastighet större än 10 m/s - i 5 % av fallen är vindhastigheten större än 15 m/s.

    Högsta uppmätta våghöjden under en 6-månadersperiod är 5.9 m - den kan sannolikt bli upp mot det dubbla.

    Strömmarna är i medeltal svaga, ofta sydgående - i extrema fall kan dock strömhastigheten uppgå till mellan 50 - 100 cm/s.

    Is förekommer i området endast under mycket svåra isvintrar, vilket inträffar mellan vart 7:e och 10:e år.

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  • 80.
    Ambjörn, Cecilia
    et al.
    SMHI, Professional Services.
    Luide, Tiina
    SMHI.
    Omstedt, Anders
    SMHI.
    Svensson, Jonny
    SMHI.
    En operationell oljedriftsmodell för norra Östersjön1981Report (Other academic)
    Abstract [en]

    A model for the forecasting of oil drift has been developed at the SMHI. The model describes the pollution on the surface by treating it as a large nurnberof particles. These particles are transported by:-

    • the surface current driven directly by the wind
    • the background circulation driven by the inclination of the sealevel
    • the turbulence of the sea

    Usually the wind driven current is calculated by reducing the wind speed by a constant factor, the wind factor. Measurements show, however, that the windfactor varies with the state of the oil and also with the wind speed. An equation is derived where the velocity profile decreases logarithmically from the surface downwards and continuously transforms into an Ekman balance at a greater depth.

    The background circulation; the currents driven by the inclination of the sea level, will be calculated by a separate vertically integrated model. The model gives the currents in the Baltic.

    Every oil particle will also be exposed to a turbulent movement, which is calculated by random technics.

    The velocity of each oil-particle can be written as

    \V = \VT + \VB + \V' where

    \VT, is the oil velocity depending on the wind, \VB is the backgroundcirculation and \V' is the turbulent oil movement.

    It is important that this model be fast and easy to handle. At the same time, the results must be reliable and of good quality. The aim is to constantlyhave an effective "emergency forecasting program" ready to operate as soon as an accident occurs .

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  • 81.
    Ambjörn, Cecilia
    et al.
    SMHI, Professional Services.
    Wickström, Kjell
    SMHI.
    Spridningsundersökningar i norra Kalmarsund för Mönsterås bruk1990Report (Other academic)
    Abstract [sv]

    Södra Skogsägarna planerar bygga ut Mönsterås Bruks massafabrik och vill därför få spridningen av avloppsvattnet i Kalmar sund belyst.

    SMHI har utfört strömmätningar i sju punkter under 3 månader våren 1990. Sex olika typiska strömningsmönster har beräknats med en tredimensionell numerisk modell. Strömmätningarna utgör drivning och verifiering av modellen samt beskriver strömmens tidsvariationer. Spridningen av avloppsvattnet har beräknats och kartering har utförts över spårämne från utsläppstuben.

    Vattnet i Kalmar sund är homogent med salthalten 7.1 - 7.6 promille. De generella strömningsmönstren i norra Kalmar sund visar att strömmen oftast är sydgående på västra sidan och nordgående ström dominerar på den östra sidan. Allmänt sett var den nordgående strömmen mot Öland relativt stabil under mätperioden. Det förhållandet inkluderar även sundet vid Skäggenäs.

    Vid nordgående nettoström genom sundet erhölls varierande strömmar mot fastlandet och nordgående vid Öland på alla djup. Vid sydgående nettoström erhölls sydlig ström på västra sidan utom i nordligaste delen, där varierande ström rådde. Mot Öland var strömmen sydgående vid Skäggenäs och norr om Borgholm var den nordgående vid hälften av tillfällena. I nordligaste delen av sundet erhölls ström mot norr vid varje tillfälle.

    Strömmarna drivs av den storskaliga cirkulationen i Östersjön. Vattenytans lutning längs kusten samt den regionala vinden visar båda tydliga samband med nettoströmmen genom sundet. I nordligaste delen av Kalmar sund är strömmen nära fastlandet relativt vindberoende. Utanför tuben från massafabriken erhölls till stor del ström mot sydost och söder med relativt höga medelhastigheter medan vinden har ett stort inflytande på strömmen vid och innanför tuben.

    Stående svängningar i Östersjön med perioden cirka 1 dygn dominerar undervissa perioder nettotransporten genom sundet. Den tredimensionella numeriska modellen har applicerats på norra Kalmar sund. Med . dess hjälp kan strömmen i hela området beräknas för olika representativa ström- och vindförhållanden. Spridningen av avloppsvattnet simuleras. Avloppsvattnet blandas relativt snabbt in på alla nivåer, eftersom vattnet i Kalmar sund oftast är välomblandat. Starka vindar medför att spridningen av avloppsvattnet blir mycket effektiv eftersom det då utsätts för varierande horisontella strömmar på olika djup. 

    Vid tillfällen med nordgående ström genom Kalmar sund förekommer ofta vind från sydväst och vid starka sydvästvindar fördelas avloppsvattnet ut i de centrala delarna av sundet. Vid svaga sydvästvindar förs avloppsvattnet norrut i centrala och östra delen av sundet. Ström mot söder förekom i samband med starka nordostvindar och starka västvindar. Nordostvindar ger en mycket snabb transport ner mot Skäggenäs, som tar drygt 2 dygn. Stark västvind för snabbt över avloppsvattnet mot Öland där det därefter relativt långsamt går söderut.

    Under islagd tid är spridningen minimal. Avloppsvattnet förs söderut eller norrut i ett smalt stråk invid kusten. Vattenutbytets betydelse för spridningen Vid en sammanvägning av resultaten från spårämnesundersökningen och modellarbetena finner vi att spridningen av avloppsvattnet i närområdet styrs av vinden. Därefter tar den storskaliga strömningen över den fortsatta spridningen. Med hjälp av en snabb initialutspädning får avloppsvattnet snabbt nästan samma densitet som recipientvattnet. Undersökningen visar att inom ett närområde på 2 km2 har avloppsvattnet hunnit spädas cirka 1 - 2 000 gånger.

    Strömmen genom Kalmar sund har en normal varaktighet på 1/2 - 2 dygn innan den skiftar riktning. Längre perioder som sällan överstiger 5 dygn med nordlig eller sydlig ström kan förekomma.

    Tidigare undersökningar visar att strömmen, sett under en längre period, är fördelad ungefär lika mellan syd- och nordgående ström. Sydgående ström förekommer cirka 60 procent av tiden och nordgående cirka 40 procent.

    På grund av de snabba skiftena av strömriktningen blir avloppsvattnet kvar i norra Kalmar sund och transporteras fram och åter under ständig utspädning. Det lämnar Kalmarsund i ett välutspädd tillstånd. Vid extremsituationer då strömmen t ex är nordgående, 10 cm per sekund under 5 dygn eller mer, lämnar avloppsvattnet Kalmar sund och går ut i Östersjön.

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  • 82.
    Ambjörn, Cecilia
    et al.
    SMHI, Professional Services.
    Wickström, Kjell
    SMHI.
    Undersökning av vattenmiljön vid utfyllnaden av Kockums varvsbassäng: Slutrapport för perioden 18 juni - 21 augusti 19871987Report (Other academic)
    Abstract [sv]

    Med anledning av SAAB-SCANIA Aktiebolags etablering inom Kockums före detta varvsområde fylls norra varvsbassängen igen med sand, hämtad från danska farvatten i Öresund. Sand tas främst från Kögebukten, men även den danska delen av Disken kan bli aktuell. Cirka tre miljoner kubikmeter sand ska under perioden juni 1987 - maj 1988 transporteras till bassängen.

    Innan utfyllnadsarbetena påbörjades togs prover för analys av metaller, PCB, klorfenoler och fenoxisyror. Dessa togs från de områden där sanden hämtas, från bottnen i varvsbassängen och från omkringliggande områden.

    Därefter tas prover regelbundet av vatten och sediment i närheten av Kockums-området. Grumlighetshalten hos ytvattnet analyseras även. En fotometer är placerad vid Ribersborgsbadet och en vid Limhamn för kontinuerlig registrering av grumlighetshalten.

    Resultat från provtagningarna i sedimenten i Kögebukten och på danska sidan av Disken visar, att alla analyserade metallhalter var låga vid jämförelse med bakgrundshalter. PCB var också lågt och i en del fall under detekteringsgränsen. Klorfenoler och fenoxisyror i Kögebukten låg under detekteringsgränsen.

    Resultat från provtagningarna i varvsbassängen före utfyllnaden och i några stationer norr och söder om denna visar följande. I sedimenten hade metallerna normala halter; kvicksilver, kadmium, bly, koppar och krom var högre än bakgrundshalterna enligt SNVs Allmänna Råd 84:4 och lägre än medelhalterna i Lommabukten. PCB var högt inne i bassängen, klorfenoler och fenoxisyror var negligerbara. För vattenproverna gällde att metallhalten var låg överallt utom för zink, vars halter genomgående var höga. PCB, klorfenoler och fenoxisyror i vattnet var negligerbara.

    Proverna tagna sedan utfyllnadsarbetet startat visar följande resultat. Den 29 juni var zinkhalten hos vattenproverna lika hög som före utfyllnadsarbetet. Övriga metaller hade låga halter i vatten och sediment. PCB var högt i sedimentet vid utflödesranden till bassängen. Den 14 juli var nickelhalten i utflödet från bassängen hög, vilket visar, att halten inne i själva bassängen var förhöjd vid detta tillfälle. Zinkhalten i vattnet var oförändrad, och kopparhalten var minst 10 gånger större än tidigare i hela området. Det kopparrika vattnet kommer utifrån och har inget lokalt ursprung. Den 20 juli var metall- och PCB-halter låga i vatten och i sediment, medan zink och koppar i vattnet hade samma halter som den 14 juli. De visar på en allmän förhöjning med avlägset ursprung.

    Musselprover togs i två punkter, och dessa gav mycket samstämmiga halter. Resultaten från musslorna skall sedan jämföras med motsvarande prover, när utfyllnadsarbetet är avslutat. Den 28 juli var zinkhalten i vattnet oförändrad. Övriga prover i sediment och vatten hade låga halter. PCB var lågt. Samma förhållanden rådde även den 4, 10 och 17 augusti.

    De förhöjda halterna av metaller som förekom innan den 15 juli i vattenområdet utanför varvsbassängen härrör med största sannolikhet från gammalt bottensediment från Kockumstiden. Genom att utfyllnaden inleddes med att bottnen täcktes med ett ca 20 cm tjockt lager sand, förhindrades därefter vidare spridning av förorenat material ut från utfyllnadsområdet. Den använda sanden från Kögebukten var enligt SMHI:s provtagning renare med lägre halter av metaller än sedimenten ute i Öresund. Efter den 15 juli, när bottenytan inne i bassängen i princip var täckt, erhölls stabila halter, och alla ämnen hade låga koncentrationer. Zink i vatten var högt men hade samma halter som innan utfyllnadsarbetena startade.

    Vid de provtagningstillfällen, då analyser av klorfenoler och fenoxisyror utförts, var halterna låga.

    Resultaten från grumlighetsundersökningarna visar, att spridningen av synligt material från utfyllnadsarbetena sker i begränsad omfattning. Vid ett tillfälle, den 15 augusti, har en förhöjd grumlighet uppmätts vid Ribersborgs kallbadhus. Vid nordgående ström har förhöjd grumlighet observerats vid några enstaka tillfällen utanför Lommabukten. I övrigt har spridningen begränsat sig till en ca 200 - 300 m stor plym strax utanför varvsbassängen.

    Spridningsberäkningarna för sedimentation och förflyttning av sandpartiklar ger information om var det lättare materialet, silt med diametern 0.01 mm, kan finnas. Det är i material med denna grovlek som oönskade ämnen finns. Bottnen i varvsbassängen var täckt omkring den 15 juli och därefter sprids i princip inga miljöfarliga ämnen härifrån. Materialet fick därför komma ut ur bassängen kontinuerligt under perioden 22 juni - 15 juli. Fördelningen på bottnen och i vattnet den 15 juli framgår av figur E, se sid 22. Därefter beräknas även föhållandena den 22 augusti, genom att det material som fanns ute den 15 juli får fortsätta att förflyttas, utan att något nytt tillförs. Resultaten från denna beräkning finns också i figur E.

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  • 83. Ameli, A. A.
    et al.
    Amvrosiadi, Nino
    Uppsala University, Sweden.
    Grabs, T.
    Laudon, H.
    Creed, I. F.
    McDonnell, J. J.
    Bishop, K.
    Hillslope permeability architecture controls on subsurface transit time distribution and flow paths2016In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 543, p. 17-30Article in journal (Refereed)
    Abstract [en]

    Defining the catchment transit time distribution remains a challenge. Here, we used a new semi-analytical physically-based integrated subsurface flow and advective–dispersive particle movement model to assess the subsurface controls on subsurface water flow paths and transit time distributions. First, we tested the efficacy of the new model for simulation of the observed groundwater dynamics at the well-studied S-transect hillslope (Västrabäcken sub-catchment, Sweden). This system, like many others, is characterized by exponential decline in saturated hydraulic conductivity and porosity with soil depth. The model performed well relative to a tracer-based estimate of transit time distribution as well as observed groundwater depth–discharge relationship within 30 m of the stream. Second, we used the model to assess the effect of changes in the subsurface permeability architecture on flow pathlines and transit time distribution in a set of virtual experiments. Vertical patterns of saturated hydraulic conductivity and porosity with soil depth significantly influenced hillslope transit time distribution. Increasing infiltration rates significantly decreased mean groundwater age, but not the distribution of transit times relative to mean groundwater age. The location of hillslope hydrologic boundaries, including the groundwater divide and no-flow boundary underlying the hillslope, changed the transit time distribution less markedly. These results can guide future decisions on the degree of complexity that is warranted in a physically-based rainfall–runoff model to efficiently and explicitly estimate time invariant subsurface pathlines and transit time distribution. 

  • 84.
    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 University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Uppsala Centre for Sustainable Development, CSD Uppsala. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. 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 distribution2016In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 30, no 14, p. 2438-2450Article in journal (Refereed)
    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.

  • 85.
    Ameli, A.A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Department of Biology, Western University, London, Ontario, Canada.
    Amvrosiadi, Nino
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Grabs, T.homas J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Laudon, Hjalmar
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Creed, I.F.
    Department of Biology, Western University, London, Ontario, Canada.
    McDonnell, J.J.
    Global Institute for Water Security, School of Environment and Sustainability, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; School of Geosciences, University of Aberdeen, Aberdeen, UK.
    Bishop, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Hillslope permeability architecture controls on subsurface transit time distribution and flow paths2016In: Journal of Hydrology, Vol. 543, no A, p. 17-30Article in journal (Refereed)
    Abstract [en]

    Defining the catchment transit time distribution remains a challenge. Here, we used a new semi-analytical physically-based integrated subsurface flow and advective–dispersive particle movement model to assess the subsurface controls on subsurface water flow paths and transit time distributions. First, we tested the efficacy of the new model for simulation of the observed groundwater dynamics at the well-studied S-transect hillslope (Västrabäcken sub-catchment, Sweden). This system, like many others, is characterized by exponential decline in saturated hydraulic conductivity and porosity with soil depth. The model performed well relative to a tracer-based estimate of transit time distribution as well as observed groundwater depth–discharge relationship within 30 m of the stream. Second, we used the model to assess the effect of changes in the subsurface permeability architecture on flow pathlines and transit time distribution in a set of virtual experiments. Vertical patterns of saturated hydraulic conductivity and porosity with soil depth significantly influenced hillslope transit time distribution. Increasing infiltration rates significantly decreased mean groundwater age, but not the distribution of transit times relative to mean groundwater age. The location of hillslope hydrologic boundaries, including the groundwater divide and no-flow boundary underlying the hillslope, changed the transit time distribution less markedly. These results can guide future decisions on the degree of complexity that is warranted in a physically-based rainfall–runoff model to efficiently and explicitly estimate time invariant subsurface pathlines and transit time distribution.

  • 86.
    Ameli, Ali A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Saskatchewan, Global Inst Water Secur, Saskatoon, SK, Canada.;Western Univ, Dept Biol, London, ON, Canada..
    Controls on subsurface transport of sorbing contaminant2017In: Hydrology Research, ISSN 1998-9563, E-ISSN 2224-7955, Vol. 48, no 5, p. 1226-1239Article in journal (Refereed)
    Abstract [en]

    Subsurface transport of a sorbing contaminant is poorly understood and characterized. Here, a new semi-analytical saturated-unsaturated flow and transport model is coupled to a kinetic sorption algorithm to assess the impact of changes in the subsurface permeability architecture and flow rate on sorption characteristics. The model outputs reveal the pronounced effect of the rate of vertical decline in K-s on the frequency of occurrence and spatial distribution of subsurface sorption as well as the timing and rate of sorbing contaminants discharged into stream. Sorption potential is weakened with infiltration rate. The impact of infiltration rate on the decline in sorption potential becomes more accentuated as the degree of subsurface vertical heterogeneity in saturated hydraulic conductivity increases. Porosity pattern also impacts sorption characteristics; but its effects highly depend upon the degree of vertical heterogeneity in Ks. The results and methodology presented in this paper have potential implications for assessing water quality in integrated groundwater-surface water systems as well as designing remediation systems.

  • 87.
    Ameli, Ali A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Saskatchewan, Global Inst Water Secur, Saskatoon, SK, Canada.;Western Univ, Dept Biol, London, ON, Canada.
    Beven, Keith
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Lancaster, Lancaster Environm Ctr, Lancaster, England..
    Erlandsson, Martin
    Stockholm Univ, Dept Phys Geog, Stockholm, Sweden..
    Creed, Irena F.
    Western Univ, Dept Biol, London, ON, Canada..
    McDonnell, Jeffrey J.
    Univ Saskatchewan, Global Inst Water Secur, Saskatoon, SK, Canada.;Univ Aberdeen, Sch Geosci, Aberdeen, Scotland.;Oregon State Univ, Dept Forest Engn Resources & Management, Corvallis, OR 97331 USA..
    Bishop, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden..
    Primary weathering rates, water transit times, and concentration-discharge relations: A theoretical analysis for the critical zone2017In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 53, no 1, p. 942-960Article in journal (Refereed)
    Abstract [en]

    The permeability architecture of the critical zone exerts a major influence on the hydrogeochemistry of the critical zone. Water flow path dynamics drive the spatiotemporal pattern of geochemical evolution and resulting streamflow concentration-discharge (C-Q) relation, but these flow paths are complex and difficult to map quantitatively. Here we couple a new integrated flow and particle tracking transport model with a general reversible Transition State Theory style dissolution rate law to explore theoretically how C-Q relations and concentration in the critical zone respond to decline in saturated hydraulic conductivity (K-s) with soil depth. We do this for a range of flow rates and mineral reaction kinetics. Our results show that for minerals with a high ratio of equilibrium concentration ( Ceq) to intrinsic weathering rate ( Rmax), vertical heterogeneity in K-s enhances the gradient of weathering-derived solute concentration in the critical zone and strengthens the inverse stream C-Q relation. As <mml:mfrac>CeqRmax</mml:mfrac> decreases, the spatial distribution of concentration in the critical zone becomes more uniform for a wide range of flow rates, and stream C-Q relation approaches chemostatic behavior, regardless of the degree of vertical heterogeneity in K-s. These findings suggest that the transport-controlled mechanisms in the hillslope can lead to chemostatic C-Q relations in the stream while the hillslope surface reaction-controlled mechanisms are associated with an inverse stream C-Q relation. In addition, as <mml:mfrac>CeqRmax</mml:mfrac> decreases, the concentration in the critical zone and stream become less dependent on groundwater age (or transit time).

  • 88.
    Ameli, Ali A.
    et al.
    Univ British Columbia, Dept Earth Ocean & Atmospher Sci, Vancouver, BC, Canada.
    Laudon, Hjalmar
    Swedish Univ Agr Sci, Dept Forest Ecol & Management, Umeå, Sweden.
    Teutschbein, Claudia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Bishop, Kevin
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Where and When to Collect Tracer Data to Diagnose Hillslope Permeability Architecture2021In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 57, no 8, article id e2020WR028719Article in journal (Refereed)
    Abstract [en]

    The permeability architecture has a major influence on hillslope flow path and hydrogeochemistry. To constrain this architecture and overcome equifinality in the diagnosis of hillslope flow paths within hydrologic transport models, different types of complementary data (e.g., tracer) have been recommended. However, there is still little information on the extent to which such complementary data can unravel the permeability architecture, and where and when to measure such data to most efficiently constrain models. Here, we couple a Richards-based flow and transport model with extensive long-term field measurements to compare the relative value of different types of hydrometric and tracer data in discriminating between contrasting permeability (or saturated hydraulic conductivity ()) architectures, in the absence of macropore flow. Our results show that compared to streamflow and water table observations, stream tracer data have a stronger evaluative potential to constrain hillslope vertical pattern in , in particular during seasons when flow is on average low (e.g., winter or summer). Tracer data from within the hillslope are even more helpful to discriminate between different vertical patterns in Ks than stream tracer data. This suggests a higher evaluative potential for hillslope tracer observations. This evaluative potential of hillslope data depends on where and when the data are collected, and increases with depth from the soil surface, with distance from the stream and during seasons when flow is low. The findings also emphasize the importance of incorporating hillslope permeability architecture in hydrologic transport models in order to reduce the uncertainty in the predictions of stream water quality.

  • 89.
    Aminjafari, Saeid
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Monitoring Water Availability in Northern Inland Waters from Space2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    River deltas and lakes support biodiversity and offer crucial ecosystem services such as freshwater provision, flood control, and fishing. However, climate change and human activities have affected deltas and lakes globally, altering the services they provide. Since delta and lake surface water occurrence and water levels respond to climate change and anthropogenic activities, we need to monitor their variations to understand the potential drivers for effective water management strategies. However, important deltas like the Selenga River Delta (SRD) in Russia lack a detailed analysis of water occurrence. Regarding lake water level, there has been a decline in the number of gauging stations globally, due to installation and maintenance costs. For example, Sweden has ~100,000 lakes which are sources of freshwater and hydro-power, but only 38 lakes have long and continuous in-situ records of water level.

    As satellite data are reliable alternatives for conventional methods to monitor deltas and lakes, I employed Earth Observations (EO) to quantify changes in surface water occurrence in the SRD and water levels in Swedish lakes and identify their main drivers. I also developed and explored a novel methodology for lake water level estimation based on Differential Interferometric Synthetic Aperture Radar (D-InSAR) by calculating the six-day phase differences in 30 Swedish lakes.

    To achieve these objectives, I trained and applied a Maximum Likelihood classification to Landsat images from 1987 to 2020 and quantified surface water occurrence and its changes in the SRD. I found that surface water occurrence in 51% of the delta experienced a decrease. As the Selenga River is the only river flowing into the SRD, the change in surface water occurrence in the SRD correlated with river discharge, but not with the river suspended sediment concentration, the lake water level in the outlet of the SRD, or evapotranspiration over the delta.

    In Sweden, I used satellite altimetry data from ERS-2, ENVISAT, JASON-1,2,3, SARAL, and Sentinel-3A/B to quantify water levels in 144 lakes from 1995-2022. I found that 52% of the lakes showed increasing trends (mostly in the north) and 43% decreasing trends (mostly in the south). Water level trends and variabilities did not correlate strongly with hydroclimatic changes (precipitation and temperature) but differed in regulated lakes compared to unregulated ones, both in the north and in the south of Sweden.

    The results of the D-InSAR method for water level estimation in two Swedish lakes (Hjälmaren and Solnen) showed that with water level changes smaller than a complete SAR phase, the phase changes correlate with in-situ water level changes with a minimum Root Mean Square Error of 0.43 cm in some pixels. In all 30 lakes, I accumulated the phase changes of each pixel throughout the whole number of interferograms to construct water levels. This method replicated the direction of water level changes shown by high Pearson’s correlations in at least one pixel in each lake.

    This thesis highlights the importance of EO for estimating surface water occurrence and lake water levels and brings focus to the future of EO through advanced space missions such as Surface Water and Ocean Topography (SWOT) and NASA-ISRO Synthetic Aperture Radar (NISAR). The findings underscore the need to continuously monitor lake water level and occurrence to adapt to climate change and understand the effects of water-regulatory schemes.

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  • 90.
    Aminjafari, Saeid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Brown, Ian
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Frappart, Frédéric
    ISPA, INRAE/Bordeaux Sciences Agro.
    Papa, Fabrice
    LEGOS, Université de Toulouse.
    Blarel, Fabien
    LEGOS, Université de Toulouse.
    Farzad, Vahidi Mayamey
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Assessing the Effects of Regulation on Swedish Lake Water Levels with Satellite AltimetryManuscript (preprint) (Other academic)
    Abstract [en]

    Lakes are important sources of freshwater for human activities and provide critical ecosystem services. However, despite having approximately 100,000 lakes, Sweden has limited continuous gauged water level data. Although satellite radar altimetry has emerged as a popular alternative to measure water levels in inland water bodies, it is yet to be exploited to understand large-scale changes in inland water bodies in Sweden. Here, we quantify the changes in water levels of 144 lakes using satellite altimetry data and in-situ gauged measurements and examine the effects of flow regulation and hydroclimatic variability. Data from multiple altimetry missions, including ERS-2, ENVISAT, JASON-1,2,3, SARAL, and Sentinel-3A/B, are employed to estimate the variability and yearly and seasonal trends of water levels in two periods, 1995-2022 and 2013-2022. Our study finds that water levels significantly increased in 52% of the lakes during 1995-2022. The increasing trends primarily occurred in northern Sweden and are potentially attributed to earlier snowmelt. On the other hand, 43% of the lakes exhibited a significant decreasing trend, which was mostly concentrated in Southern Sweden. Dividing the set of lakes into regulated and unregulated groups shows how lake regulation in Sweden can partly explain the spatial patterns of water levels and their variability. This study highlights the need to continuously monitor lake water levels for adaptation strategies in the face of climate change and understand the downstream effects of water regulatory schemes.

  • 91.
    Aminjafari, Saeid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Brown, Ian
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Vahidi Mayamey, Farzad
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Tracking Centimeter-Scale Water Level Changes in Swedish Lakes Using D-InSAR2024In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 60, no 2, article id e2022WR034290Article in journal (Refereed)
    Abstract [en]

    Lakes are valuable water resources that support aquatic and terrestrial ecosystems and supply fresh water for the agricultural, industrial, and urban sectors worldwide. Although water levels should be tracked to monitor these services, conventional gauging is unfeasible in most lakes. This study applies Differential Interferometric Synthetic Aperture Radar (D-InSAR) to estimate small water level changes, less than 2 cm, in Swedish lakes over 6-day intervals. We validated the method across the shores of 30 Swedish lakes with gauged observations in 2019. We used Sentinel-1A/B images with a 6-day temporal separation to construct consecutive interferograms and accumulated the phase changes in pixels of high coherence to build a time series of water levels. We find that the accumulated phase change obtained by D-InSAR replicates the magnitude of water levels in seven lakes in Southern Sweden, where water levels change slowly, less than 2 cm per 6-day period, as validated by in-situ gauges. In addition, this study demonstrates the application of D-InSAR to estimate the long-term direction of water level change (i.e., increase or decrease) in all 30 lakes. This work reveals the utility of high temporal resolution water level observations in support of other satellite water level instruments such as conventional altimeters and the recently launched Surface Water and Ocean Topography Mission.

  • 92. Aminot, A
    et al.
    Kirkwood, D
    Carlberg, Stig
    SMHI, Research Department, Oceanography.
    The QUASIMEME laboratory performance studies (1993-1995): Overview of the nutrients section1997In: Marine Pollution Bulletin, ISSN 0025-326X, E-ISSN 1879-3363, Vol. 35, no 1-6, p. 28-41Article in journal (Refereed)
    Abstract [en]

    The QUASIMEME Project (1993-1996) was established to assist European laboratories to improve the data they produce in marine monitoring programmes. Through laboratory performance Studies (with six-monthly reports), workshops and expert visits the programme was fully interactive. There were five rounds of laboratory performance studies. For the nutrient section, in which about 50 laboratories took part, the reference materials distributed to the participants consisted of standard solutions of nutrients and seawater samples stabilized by autoclaving. The material included low and high concentrations typical of those encountered in coastal seawater; at least two samples with different concentrations were distributed in each round. Robust statistics were used to determine the means and standard deviations for each set of results. For inorganic nutrients, the assessment of the data for bias and precision was based mainly on a Z- and P-scoring system in which targets of +/- 6% were allocated to the high concentrations, likewise +/- 12.5% to the low concentrations. This overview discusses overall performance separately for nitrate plus nitrite, nitrite, ammonia, phosphate, total nitrogen and total phosphorus, and classifies the performance of individual laboratories in each round, while maintaining their anonymity. Performance for nitrate plus nitrite and nitrite improved steadily and these determinands are now fully under control; at the end of the programme, standard deviations (SD) for nitrate plus nitrite were 0.2 mu mol l(-1) at low concentration and 0.6 mu mol l(-1) (4%) at high concentration, and for nitrite they were 0.03 mu mol l(-1) and 0.06 mu mol l(-1) (5%) respectively. Phosphate showed a somewhat stable level of performance with SD of 0.06 mu mol l(-1) and 0.10 mu mol l(-1) (10%) at low and high concentrations respectively, but this could be improved. Ammonia proved the most difficult to determine, and in spite of a substantial improvement at the beginning of the exercise, this determinand is not under control in many laboratories. At low concentrations, ammonia shows a positive bias of 0.2 mu mol l(-1) and a SD of 0.3 mu mol l(-1), while at high concentrations SD reaches 0.5 mu mol l(-1) (20%). For total nitrogen (TN) and total phosphorus (TP), the exercises show that only two thirds of the participants produced consistent data for TN, and less than half of them produced consistent data for TP. (C) 1997 Elsevier Science Ltd. All rights reserved.

  • 93. Amir-Heidari, Payam
    et al.
    Arneborg, Lars
    SMHI, Research Department, Oceanography.
    Lindgren, J. Fredrik
    Lindhe, Andreas
    Rosen, Lars
    Raie, Mohammad
    Axell, Lars
    SMHI, Research Department, Oceanography.
    Hassellov, Ida-Maja
    A state-of-the-art model for spatial and stochastic oil spill risk assessment: A case study of oil spill from a shipwreck2019In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 126, p. 309-320Article in journal (Refereed)
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  • 94. Amiri, V.
    et al.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. iversity of Southern Queensland, Toowoomba, QLD 4350, Australia.
    Nakhaei, M.
    The hydrogeochemical evaluation of groundwater resources and their suitability for agricultural and industrial uses in an arid area of Iran2021In: Groundwater for Sustainable Development, ISSN 2352-801X, Vol. 12, article id 100527Article in journal (Refereed)
    Abstract [en]

    The hydrogeochemical and quality status of groundwater resources in Yazd province, the central plateau of Iran, has been investigated. The most common water type, followed by chemical facies in this study area, is Cl type (with 50.46%) and Na–Cl facies (47.71%), respectively. Besides, the most samples with industrial and agricultural uses show the Cl type and Na–Cl hydrochemical facies. The position of samples on the Gibbs and van Wirdum diagrams indicate that the water-rock interaction and dissolution of evaporites are the main controlling process of water chemistry. Distribution of samples based on Na/Cl vs. EC, Ca + Mg vs. SO4 + HCO3, and Na–Cl vs. Ca + Mg–SO4–HCO3 highlight the significant role of direct ion exchange in water chemistry change. The water quality for agricultural use is assessed based on some indices including EC, Na%, sodium absorption ratio (SAR), residual sodium carbonate (RSC), magnesium absorption ratio (MAR), permeability index (PI), Kelly's ratio (KR), and Wilcox diagram. In general, the water quality for irrigation purposes is mainly excellent to permissible. The water quality assessment for industrial purposes is performed using some indices including Langelier Saturation Index (LSI), Ryznar Stability Index (RSI), Larson-Skold Index (L-SI), Puckorious scaling index (PSI), and total hardness (TH). Based on these indices, most groundwater samples have mild to high potential to corrode the equipment and pipelines.

  • 95.
    Amiri, Vahab
    et al.
    Department of Geology, Faculty of Science, Yazd University, Yazd, Iran.
    Li, Peiyue
    School of Water and Environment, Chang’an University, No. 126 Yanta Road, Xi’an, 710054, China Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of the Ministry of Education, Chang’an University, No. 126 Yanta Road, Xi’an, 710054, China.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering. KWR Water Cycle Research Institute, Groningenhaven 7, 3433 PE, Nieuwegein, The Netherlands.
    Nakhaei, Mohammad
    Department of Applied Geology, Faculty of Earth Science, Kharazmi University, Tehran, Iran.
    Mercury pollution in the coastal Urmia aquifer in northwestern Iran: potential sources, mobility, and toxicity2021In: Environmental Science and Pollution Research, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 28, no 14, p. 17546-17562Article in journal (Refereed)
    Abstract [en]

    The concentration of total dissolved mercury (HgT) in surface and groundwater resources in the coastal parts of Urmia aquifer (NW of Iran) was investigated to identify the possible sources and sinks of mercury and the geochemical mechanisms controlling its mobilization. The distribution of water samples on the Piper diagram demonstrates that most samples have the Ca-Mg-HCO3 facies. From 62 water samples collected in this area, one sample contained HgT concentrations exceeding the maximum contaminant level recommended by the WHO (6 μg/L). The principal component analysis (PCA) produced five principal components. The positive moderate correlation of HgT with EC, Cl, K, Mg, and Na indicated that the weathering of geological formations was one of the main sources of mercury in groundwater samples. Position of water samples in Eh-pH regions where microorganisms involved in mercury methylation and mineralization were potentially active demonstrated that the aquifer had undergone sulfate reduction and had reached the final stage of the terminal electron accepting process (TEAP) sequence in the methane production processes which are limited to only 37% of the water samples that have anaerobic conditions. Some Hg-bearing species are in nonequilibrium geochemical conditions. The supersaturation of water samples with magnetite and goethite indicated that these Fe-bearing minerals could act as the strong reducing agents for the reduction of Hg(II) to Hg(0).

  • 96.
    Amland, Sølvi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Hvor er de markene i Sverige som er mest sensitive ovenfor forsuring og nitrogentap?2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Several factors affect whether the ground is prone to acidification and nitrogen loss. Removal of biological materials is an important factor that can trigger this. In Sweden, three dominant forest tree species are spruce, pine and birch trees. For forestry purposes, these trees are being logged at their potimal harvesting ages which are averaged at 70 years of age. This is of interest beacuse the forest ages can be used to predict future forestry practices, specifically in Dalarna, Sweden. The forest ages were observed at a catchment based level so that the effects of forestry can easily be measured. It was found that cathcments in the north of Dalarna consist of higher percentages of forest over the age of 70 in comparsion to the south and areas surrounding lakes. From this, it is expected that forestry will occur in the near future in the north.

    Hopefully the work that has been done in Dalarna, can be used as a model for the rest of Sweden.

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  • 97. Amortegui, Julio Cesar Espana
    et al.
    Pekar, Heidi
    Retrato, Mark Dennis Chico
    Persson, Malin
    Karlson, Bengt
    SMHI, Research Department, Oceanography.
    Bergquist, Jonas
    Zuberovic-Muratovic, Aida
    LC-MS/MS Analysis of Cyanotoxins in Bivalve Mollusks-Method Development, Validation and First Evidence of Occurrence of Nodularin in Mussels (Mytilus edulis) and Oysters (Magallana gigas) from the West Coast of Sweden2023In: Toxins, ISSN 2072-6651, E-ISSN 2072-6651, Vol. 15, no 5, article id 329Article in journal (Refereed)
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    LC-MS/MS Analysis of Cyanotoxins in Bivalve Mollusks—Method Development, Validation and First Evidence of Occurrence of Nodularin in Mussels (Mytilus edulis) and Oysters (Magallana gigas) from the West Coast of Sweden
  • 98. Amundin, Mats
    et al.
    Carlstrom, Julia
    Thomas, Len
    Carlen, Ida
    Teilmann, Jonas
    Tougaard, Jakob
    Loisa, Olli
    Kyhn, Line A.
    Sveegaard, Signe
    Burt, M. Louise
    Pawliczka, Iwona
    Koza, Radomil
    Arciszewski, Bartlomiej
    Galatius, Anders
    Laaksonlaita, Jussi
    MacAuley, Jamie
    Wright, Andrew J.
    Gallus, Anja
    Dahne, Michael
    Acevedo-Gutierrez, Alejandro
    Benke, Harald
    Koblitz, Jens
    Tregenza, Nick
    Wennerberg, Daniel
    SMHI, Core Services.
    Brundiers, Katharina
    Kosecka, Monika
    Tiberi Ljungqvist, Cinthia
    Jussi, Ivar
    Jabbusch, Martin
    Lyytinen, Sami
    Saskov, Aleksej
    Blankett, Penina
    Estimating the abundance of the critically endangered Baltic Proper harbour porpoise (Phocoena phocoena) population using passive acoustic monitoring2022In: Ecology and Evolution, E-ISSN 2045-7758, Vol. 12, no 2, article id e8554Article in journal (Refereed)
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    Estimating the abundance of the critically endangered Baltic Proper harbour porpoise (Phocoena phocoena) population using passive acoustic monitoring
  • 99. Amvrosiadi, Nino
    Seibert, Jan (Contributor)
    Soil moisture storage estimation based on steady vertical fluxes under equilibrium2017In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 553, p. 798-804Article in journal (Refereed)
    Abstract [en]

    Soil moisture is an important variable for hillslope and catchment hydrology. There are various computational methods to estimate soil moisture and their complexity varies greatly: from one box with vertically constant volumetric soil water content to fully saturated-unsaturated coupled physically-based models. Different complexity levels are applicable depending on the simulation scale, computational time limitations, input data and knowledge about the parameters. The Vertical Equilibrium Model (VEM) is a simple approach to estimate the catchment-wide soil water storage at a daily time-scale on the basis of water table level observations, soil properties and an assumption of hydrological equilibrium without vertical fluxes above the water table. In this study VEM was extended by considering vertical fluxes, which allows conditions with evaporation and infiltration to be represented. The aim was to test the hypothesis that the simulated volumetric soil water content significantly depends on vertical fluxes. The water content difference between the no-flux, equilibrium approach and the new constant-flux approach greatly depended on the soil textural class, ranging between similar to 1% for silty clay and similar to 44% for sand at an evapotranspiration rate of 5 mm.d(-1). The two approaches gave a mean volumetric soil water content difference of 1 mm for two case studies (sandy loam and organic rich soils). The results showed that for many soil types the differences in estimated storage between the no-flux and the constant flux approaches were relatively small.

  • 100.
    Amvrosiadi, Nino
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Temporal Dynamics of Total Organic Carbon Export Rates in Swedish Streams: Importance of discharge conditions and seasonal effects2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The amount of total organic carbon (TOC) in water is a rough indicator of the waterquality. Driven by the question how the TOC concentration would vary acrossstreams in Sweden under different climate conditions (e.g. more extreme dischargeevents), the temporal dynamics of TOC were examined for different stream subgroupswith six orders of magnitude catchment area span. In addition, the relationshipbetween dissolved inorganic carbon (DIC) export (both downstream and evasion) anddischarge conditions was also studied. Another question addressed was if the amountof TOC exported can be affected by export conditions dominating the previousseason. TOC export followed closely the discharge, which is in agreement withprevious studies, and all 42 catchments studied across Sweden were described by thispositive relationship regardless their size. A linear TOC export response to dischargewas identified during extreme discharge conditions. Furthermore, the TOC export wassignificantly related to the antecedent TOC export conditions for approximately halfof the 18 studied catchments with areas ranging between 2.5·10-3 and 67 km2.

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    Temporal Dynamics of Total Organic Carbon Export Rates in Swedish Streams: Importance of discharge conditions and seasonal effects
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