| 1. |
- Blösch, Günter, et al.
(författare)
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Twenty-three unsolved problems in hydrology (UPH) - a community perspective
- 2019
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 64:10, s. 1141-1158
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Tidskriftsartikel (refereegranskat)abstract
- This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come.
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| 2. |
- Kløve, Bjørn, et al.
(författare)
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Groundwater dependent ecosystems : Part I: Hydroecological status and trends
- 2011
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Ingår i: Environmental Science and Policy. - : Elsevier BV. - 1462-9011 .- 1873-6416. ; 14:7, s. 770-781
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Tidskriftsartikel (refereegranskat)abstract
- Groundwater dependent ecosystems (GDEs) include valuable ecosystems such as springs, wetlands, rivers, lakes and lagoons. The protection of these systems and services they provide is highlighted by international agreements, i.e. Ramsar convention on wetlands, and regional legislation, i.e. the European Water Framework Directive. Groundwater provides water, nutrients and a relatively stable temperature. However, the role of groundwater in surface ecosystems is not fully understood. The ecosystem can depend on groundwater directly or indirectly, and the reliance can be continuous, seasonal or occasional. This has implications for the vulnerability of ecosystems, as some may be easily affected by external pressure. Conceptual models and quantitative assessments of how groundwater interacts with the environment are needed. GDEs are also threatened by different land use activities and climate change. Hence, we need to understand how GDEs are affected by changes in groundwater quantity and quality, as severe groundwater changes have been observed in many regions. This study examines key aspects of GDEs (hydrogeology, geochemistry and biodiversity) in order to improve conceptual understanding of the role of groundwater in such ecosystems. The status and baseline of different types of GDEs are discussed, with particular emphasis on past evidence of environmental change and potential thresholds and threats in GDEs in various parts of Europe with different land use, climate and geology
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| 3. |
- Kløve, Bjørn, et al.
(författare)
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Groundwater surface water interaction in GDE
- 2012
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Rapport (populärvet., debatt m.m.)abstract
- This report reviews and discussed the interaction of groundwaterin GDEs. The report presents and integrates past and new results.Different methods used to measure groundwater interaction withecosystems are presented. Various GENESIS case studies acrossEurope to demonstrate the variable and complex role ofgroundwater in GDEs. The basis for developing conceptual for GDEsis presented. Various methods to model GDEs are discussed.
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| 4. |
- Refsgaard, Jens Christian, et al.
(författare)
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Spatially differentiated regulation : Can it save the Baltic Sea from excessive N-loads?
- 2019
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Ingår i: Ambio. - : SPRINGER. - 0044-7447 .- 1654-7209. ; 48:11, s. 1278-1289
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Tidskriftsartikel (refereegranskat)abstract
- The Baltic Sea Action Plan and the EU Water Framework Directive both require substantial additional reductions of nutrient loads (N and P) to the marine environment. Focusing on nitrogen, we present a widely applicable concept for spatially differentiated regulation, exploiting the large spatial variations in the natural removal of nitrate in groundwater and surface water. By targeting mitigation measures towards areas where nature's own capacity for removal is low, spatially differentiated regulation can be more cost-effective than the traditional uniform regulation. We present a methodology for upscaling local modelling results on targeted measures at field scale to Baltic Sea drainage basin scale. The paper assesses the potential gain and discusses key challenges related to implementation of spatially differentiated regulation, including the need for more scientific knowledge, handling of uncertainties, practical constraints related to agricultural practice and introduction of co-governance regimes.
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| 5. |
- Wörman, Anders, 1961-, et al.
(författare)
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Kinematic model of solute transport in stream networks : Example with phosphate retention in Morsa watershed, Norway
- 2004
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Ingår i: Archives of Hydro-engineering and Environmental Mechanics. - 1231-3726. ; 51:1, s. 41-53
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical description of reactive solute transport in a network of stream channels is derived by convoluting unit solutions based on a physical representation of transport and topographical information of the distributions of solute load as well as pathways. The theory is applied to a generic analysis of the phosphate export in Morsa watershed due to the load from 620 individual households with a local wastewater treatment. Essential factors for the phosphate export is filtering of the water in stream-bed sediments through a distribution of hyporheic flow paths of various lengths. This generic study indicates that a significant portion of phosphate is retained in the hyporheic zones for a long time. The 90% recovery time following a hypothetical remediation action in the households is expected to be in the order of one decade.
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| 6. |
- Wörman, Anders, et al.
(författare)
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Reach scale and evaluation methods as limitations for transient storage properties in streams and rivers
- 2007
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Ingår i: Water resources research. - : American Geophysical Union (AGU). - 0043-1397 .- 1944-7973. ; 43:10
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Tidskriftsartikel (refereegranskat)abstract
- The value of stream tracer tests depends on appropriate experimental design, accurate evaluation methods and careful generalization of results with account taken to relevant limitations. This paper examines six calibration methods for transient storage models and effects of parameter errors on model generalizations. The residence time of transient storage and retardation factor varied a factor of 8 and 27, respectively, with the choice of method. Methods that emphasize the tail of the tracer breakthrough, such as optimization of log-concentrations, are required to provide accurate estimates of transient storage parameters, whereas optimization using normal values can lead to substantial errors. Moment matching techniques require a solute mass-recovery higher than about 70% for a reliable estimate of the storage capacity. The pumping model provided good estimates of the storage in the hyporheic zone under different stream discharges at two tracer test events with tritiated water in the Hobol River, Norway. The accuracy of the evaluation of the transient storage parameters decreases with distance in the stream caused primarily by decreasing precision in the measurements and insufficient mass-recovery. With distance, more and more time-scales representing the hyporheic zone flow are also manifested as signatures of the tracer breakthrough. In a stream-landscape groundwater system that is characterized by multiple residence time-scales, stream tracer results are limited to specific reach distances and need to be supported by theory or other data when generalized to longer distances.
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