| 1. |
- van der Velde, Ype, et al.
(författare)
-
Consequences of mixing assumptions for time-variable travel time distributions
- 2015
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 29:16, s. 3460-3474
-
Tidskriftsartikel (refereegranskat)abstract
- The current generation of catchment travel time distribution (TTD) research, integrating nearly three decades of work since publication of Water's Journey from Rain to Stream, seeks to represent the full distribution in catchment travel times and its temporal variability. Here, we compare conceptualizations of increasing complexity with regards to mixing of water storages and evaluate how these assumptions influence time-variable TTD estimates for two catchments with contrasting climates: the Gardsjon catchment in Sweden and the Marshall Gulch catchment in Arizona, USA. Our results highlight that, as long as catchment TTDs cannot be measured directly but need to be inferred from input-output signals of catchments, the inferred catchment TTDs depend strongly on the underlying assumptions of mixing within a catchment. Furthermore, we found that the conceptualization of the evapotranspiration flux strongly influences the inferred travel times of stream discharge. For the wet and forested Gardsjon catchment in Sweden, we inferred that evapotranspiration most likely resembles a completely mixed sample of the water stored in the catchment; however, for the drier Marshall Gulch catchment in Arizona, evapotranspiration predominantly contained the younger water stored in the catchment. For the Marshall Gulch catchment, this higher probability for young water in evapotranspiration resulted in older water in the stream compared to travel times inferred with assumptions of complete mixing. New observations that focus on the TTD of the evapotranspiration flux and the actual travel time of water through a catchment are necessary to improve identification of mixing and consequently travel times of stream water. Copyright (c) 2014 John Wiley & Sons, Ltd.
|
|
| 2. |
- Andersson-Sköld, Yvonne, et al.
(författare)
-
An integrated method for assessing climate-related risks and adaptation alternatives in urban areas
- 2015
-
Ingår i: Climate Risk Management. - : Elsevier BV. - 2212-0963. ; 7, s. 31-50
-
Tidskriftsartikel (refereegranskat)abstract
- © 2015 The Authors. The urban environment is a complex structure with interlinked social, ecological and technical structures. Global warming is expected to have a broad variety of impacts, which will add to the complexity. Climate changes will force adaptation, to reduce climate-related risks. Adaptation measures can address one aspect at the time, or aim for a holistic approach to avoid maladaptation. This paper presents a systematic, integrated approach for assessing alternatives for reducing the risks of heat waves, flooding and air pollution in urban settings, with the aim of reducing the risk of maladaptation. The study includes strategies covering different spatial scales, and both the current climate situation and the climate predicted under climate change scenarios. The adaptation strategies investigated included increasing vegetation; selecting density, height and colour of buildings; and retreat or resist (defend) against sea-level rise. Their effectiveness was assessed with regard to not only flooding, heat stress and air quality but also with regard to resource use, emissions to air (incl. GHG), soil and water, and people's perceptions and vulnerability. The effectiveness of the strategies were ranked on a common scale (from -3 to 3) in an integrated assessment. Integrated assessments are recommended, as they help identify the most sustainable solutions, but to reduce the risk of maladaptation they require experts from a variety of disciplines. The most generally applicable recommendation, derived from the integrated assessment here, taking into account both expertise from different municipal departments, literature surveys, life cycle assessments and publics perceptions, is to increase the urban greenery, as it contributes to several positive aspects such as heat stress mitigation, air quality improvement, effective storm-water and flood-risk management, and it has several positive social impacts. The most favourable alternative was compact, mid-rise, light coloured building design with large parks/green areas and trees near buildings.
|
|
| 3. |
- Temnerud, Johan, et al.
(författare)
-
Map-based prediction of organic carbon in headwater streams improved by downstream observations from the river outlet
- 2016
-
Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 13:2, s. 399-413
-
Tidskriftsartikel (refereegranskat)abstract
- In spite of the great abundance and ecological importance of headwater streams, managers are usually limited by a lack of information about water chemistry in these headwaters. In this study we test whether river outlet chemistry can be used as an additional source of information to improve the prediction of the chemistry of upstream headwaters (size < 2 km(2)), relative to models based on map information alone. We use the concentration of total organic carbon (TOC), an important stream ecosystem parameter, as the target for our study. Between 2000 and 2008, we carried out 17 synoptic surveys in 9 mesoscale catchments (size 32-235 km(2)). Over 900 water samples were collected in total, primarily from headwater streams but also including each catchment's river outlet during every survey. First we used partial least square regression (PLS) to model the distribution (median, interquartile range (IQR)) of headwater stream TOC for a given catchment, based on a large number of candidate variables including sub-catchment characteristics from GIS, and measured river chemistry at the catchment outlet. The best candidate variables from the PLS models were then used in hierarchical linear mixed models (MM) to model TOC in individual headwater streams. Three predictor variables were consistently selected for the MM calibration sets: (1) proportion of forested wetlands in the sub-catchment (positively correlated with headwater stream TOC), (2) proportion of lake surface cover in the sub-catchment (negatively correlated with headwater stream TOC), and (3) river outlet TOC (positively correlated with headwater stream TOC). Including river outlet TOC improved predictions, with 5-15% lower prediction errors than when using map information alone. Thus, data on water chemistry measured at river outlets offer information which can complement GIS-based modelling of headwater stream chemistry.
|
|
| 4. |
- Jacobson, Lisa, et al.
(författare)
-
Tipping to staying on the ground : Internalized knowledge of climate change crucial for transformed air travel behavior
- 2020
-
Ingår i: Sustainability. - : MDPI. - 2071-1050. ; 12:5
-
Tidskriftsartikel (refereegranskat)abstract
- Air travel accounts for a major share of individual greenhouse gas emissions, particularly for people in high-income countries. Until recently, few have reduced flying because of climate concerns, but currently, a movement for staying on the ground is rising. Sweden has been a focal point for this movement, particularly during 2018–2019, when a flight tax was introduced, and air travel reduction was intensely discussed in the media. We performed semi-structured interviews with Swedish residents, focusing primarily on individuals who have reduced flying because of its climate impact. We explore how such individual transformation of air travel behavior comes about, and the phases and components of this process. Applying a framework of sustainability transformation, we identify incentives and barriers in personal and political spheres. We show that internalized knowledge about climate change and the impact of air travel is crucial for instigating behavioral change. Awareness evokes negative emotions leading to a personal tipping point where a decision to reduce or quit flying is made. However, the process is often counteracted by both personal values and political structures promoting air travel. Even individuals with a strong drive to reduce flying feel trapped in social practices, norms and infrastructures. Hence, we argue that personal and political spheres interact complexly and to reduce flying at larger scales, interventions are needed across spheres, e.g., change of norms, effective policy instruments and better alternatives to air travel.
|
|
| 5. |
- Reynolds, Eduardo, et al.
(författare)
-
Robustness of flood-model calibration using single and multiple events
- 2019
-
Ingår i: Hydrological Sciences Journal. - Oxon : Taylor & Francis. - 0262-6667 .- 2150-3435. ; 65:5, s. 842-853
-
Tidskriftsartikel (refereegranskat)abstract
- Lack of discharge data for model calibration is challenging for flood prediction in ungauged basins. Since establishment and maintenance of a permanent discharge station is resource demanding, a possible remedy could be to measure discharge only for a few events. We tested the hypothesis that a few flood-event hydrographs in a tropical basin would be sufficient to calibrate a bucket-type rainfall-runoff model, namely the HBV model, and proposed a new event-based calibration method to adequately predict floods. Parameter sets were chosen based on calibration of different scenarios of data availability, and their ability to predict floods was assessed. Compared to not having any discharge data, flood predictions improved already when one event was used for calibration. The results further suggest that two to four events for calibration may considerably improve flood predictions with regard to accuracy and uncertainty reduction, whereas adding more events beyond this resulted in small performance gains.
|
|
| 6. |
- Ekström, Sara M., et al.
(författare)
-
Increasing concentrations of iron in surface waters as a consequence of reducing conditions in the catchment area
- 2016
-
Ingår i: Journal of Geophysical Research - Biogeosciences. - 2169-8953 .- 2169-8961. ; 121:2, s. 479-493
-
Tidskriftsartikel (refereegranskat)abstract
- Recent studies report trends of strongly increasing iron (Fe) concentrations in freshwaters. Since Fe is a key element with a decisive role in the biogeochemical cycling of major elements, it is important to understand the mechanisms behind these trends. We hypothesized that variations in Fe concentration are driven mainly by redox dynamics in hydraulically connected soils. Notably, Fe(III), which is the favored oxidation state except in environments where microbial activity provide strong reducing intensity, has several orders of magnitude lower water solubility than Fe(II). To test our hypothesis, seasonal variation in water chemistry, discharge, and air temperature was studied in three Swedish rivers. Methylmercury and sulfate were used as indicators of seasonal redox changes. Seasonal variability in water chemistry, discharge, and air temperature in the Eman and Lyckeby Rivers implied that the variation in Fe was primarily driven by the prevalence of reducing conditions in the catchment. In general, high Fe concentrations were observed when methylmercury was high and sulfate was low, indicative of reducing conditions. The Fe concentrations showed no or weak relationships with variations in dissolved organic matter concentration and aromaticity. The seasonal variation in Fe concentration of the Ume river was primarily dependent on timing of the snowmelt in high- versus low-altitude areas of the catchment. There were long-term trends of increasing temperature in all catchments and also trends of increasing discharge in the southern rivers, which should increase the probability for anaerobic conditions in space and time and thereby increase Fe transport to the aquatic systems.
|
|
| 7. |
- Norén, Viveca, 1972-, et al.
(författare)
-
Flood riskassessment – Practices in flood prone Swedish municipalities
- 2016
-
Ingår i: International Journal of Disaster Risk Reduction. - Uppsala Univ, Dept Earth Sci, Villavagen, SE-75236 Uppsala, Sweden. [Noren, Viveca; Bishop, Kevin] Uppsala Univ, Dept Earth Sci, Villavagen 16, SE-75236 Uppsala, Sweden. [Noren, Viveca; Nyberg, Lars; Bishop, Kevin] Uppsala Univ, Ctr Nat Disaster Sci, Villavagen 16, SE-75236 Uppsala, Sweden. [Hedelin, Beatrice; Nyberg, Lars] Karlstad Univ, Dept Environm & Life Sci, Ctr Climate & Safety, SE-65188 Karlstad, Sweden. [Bishop, Kevin] Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, POB 7050, SE-75007 Uppsala, Sweden. : Elsevier. - 2212-4209. ; 18, s. 206-217
-
Tidskriftsartikel (refereegranskat)abstract
- Risk assessments are important to ensure efficient and effective flood risk management. Methods and strategies for flood risk assessment are described in the literature, but less is known about how assessments are actually performed. We have studied local flood risk assessments in Sweden by interviewing flood risk managers in municipalities and analyzing documentation of flood risk assessment efforts.There is a large variation between municipalities in how flood risk assessment has been done. The efforts made in association with the EU Floods Directive together with a Government Commission about a flood in Lake Mälaren are the most advanced assessments. Only a few of the municipalities have done comparable assessments. Generally, however, there is a lack of experience and theoretical knowledge about concepts and methods of flood risk assessment in the municipalities. In the assessments studied, the flood it self had been rather well defined in hazard maps. The consequences of a flood had been studied in the larger projects but only by half of the municipalities. It is mainly direct, tangible consequences that have been included. It is mainly the exposure of assets that has been investigated while little attention has been paid to vulnerability. To improve flood risk assessment in Sweden there is a need for knowledge and resources in the municipalities. Prioritization and motivation are needed to actually perform the assessments. National guidelines for may be helpful to guide municipalities in this work and to have more uniform risk assessment.
|
|
| 8. |
- Anderson, Leif G, 1951, et al.
(författare)
-
Shelf-Basin interaction along the East Siberian Sea
- 2017
-
Ingår i: Ocean Science. - : Copernicus GmbH. - 1812-0784 .- 1812-0792. ; 13:2, s. 349-363
-
Tidskriftsartikel (refereegranskat)abstract
- Extensive biogeochemical transformation of organic matter takes place in the shallow continental shelf seas of Siberia. This, in combination with brine production from sea-ice formation, results in cold bottom waters with relatively high salinity and nutrient concentrations, as well as low oxygen and pH levels. Data from the SWERUS-C3 expedition with icebreaker Oden, from July to September 2014, show the distribution of such nutrient-rich, cold bottom waters along the continental margin from about 140 to 180 degrees E. The water with maximum nutrient concentration, classically named the upper halocline, is absent over the Lomonosov Ridge at 140 degrees E, while it appears in the Makarov Basin at 150 degrees E and intensifies further eastwards. At the intercept between the Mendeleev Ridge and the East Siberian continental shelf slope, the nutrient maximum is still intense, but distributed across a larger depth interval. The nutrient-rich water is found here at salinities of up to similar to 34.5, i.e. in the water classically named lower halocline. East of 170 degrees E transient tracers show significantly less ventilated waters below about 150 m water depth. This likely results from a local isolation of waters over the Chukchi Abyssal Plain as the boundary current from the west is steered away from this area by the bathymetry of the Mendeleev Ridge. The water with salinities of similar to 34.5 has high nutrients and low oxygen concentrations as well as low pH, typically indicating decay of organic matter. A deficit in nitrate relative to phosphate suggests that this process partly occurs under hypoxia. We conclude that the high nutrient water with salinity similar to 34.5 are formed on the shelf slope in the Mendeleev Ridge region from interior basin water that is trapped for enough time to attain its signature through interaction with the sediment.
|
|
| 9. |
- Tehler, Henrik, et al.
(författare)
-
Evidence-based disaster risk management : A scoping review focusing on risk, resilience and vulnerability assessment
- 2024
-
Ingår i: Progress in Disaster Science. - : Elsevier. - 2590-0617. ; 23
-
Tidskriftsartikel (refereegranskat)abstract
- A plethora of methods exist to aid decision-making in mitigating disaster risk, many of which fall into the categories of risk, vulnerability and/or resilience assessment methods. The objective of the present study is to provide an overview of these methods, with a particular focus on evidence that supports their practical implementation. A scoping study of scientific literature reveal 97 distinct methods. Despite the growing interest in publishing new methods, there seems to be a lack of focus on demonstrating their effectiveness in practice. The few contributions that do include some forms of evaluation typically do so by comparing the method’s output with disaster data, by contrasting it with the output of other methods, by having experts evaluate the structure of the method, or by testing the method in practice and evaluating its usage. To further strengthen the relevance of research on this topic, increased attention should be paid to this matter. A good starting point would be to use the ways of evaluation identified in this study and systematically present evidence regarding the practical usefulness of methods for risk, vulnerability and/or resilience assessment.
|
|
| 10. |
- Balk, Lennart, et al.
(författare)
-
Widespread episodic thiamine deficiency in Northern Hemisphere wildlife
- 2016
-
Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Many wildlife populations are declining at rates higher than can be explained by known threats to biodiversity. Recently, thiamine (vitamin B-1) deficiency has emerged as a possible contributing cause. Here, thiamine status was systematically investigated in three animal classes: bivalves, ray-finned fishes, and birds. Thiamine diphosphate is required as a cofactor in at least five life-sustaining enzymes that are required for basic cellular metabolism. Analysis of different phosphorylated forms of thiamine, as well as of activities and amount of holoenzyme and apoenzyme forms of thiaminedependent enzymes, revealed episodically occurring thiamine deficiency in all three animal classes. These biochemical effects were also linked to secondary effects on growth, condition, liver size, blood chemistry and composition, histopathology, swimming behaviour and endurance, parasite infestation, and reproduction. It is unlikely that the thiamine deficiency is caused by impaired phosphorylation within the cells. Rather, the results point towards insufficient amounts of thiamine in the food. By investigating a large geographic area, by extending the focus from lethal to sublethal thiamine deficiency, and by linking biochemical alterations to secondary effects, we demonstrate that the problem of thiamine deficiency is considerably more widespread and severe than previously reported.
|
|
