| 1. |
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| 2. |
- Tranvik, Lena, et al.
(författare)
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Reglerad mångfald
- 2014
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Ingår i: Älvräddaren. - 0282-1354. ; 2014, s. 17-19
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Ingress: Vattendrag med opåverkade flöden och stränder har stora förutsättningar för höga naturvärden. Vattnets dynamik skapar variation i både strandstruktur och bottensubstrat och därmed förutsättningar för variationsrika livsmiljöer.
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| 3. |
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| 4. |
- Göteman, Malin, 1980-
(författare)
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Wave energy parks with point-absorbers of different dimensions
- 2017
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Ingår i: Journal of Fluids and Structures. - : Elsevier BV. - 0889-9746 .- 1095-8622. ; 74, s. 142-157
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Tidskriftsartikel (refereegranskat)abstract
- An analytical model for point-absorbing wave energy converters connected to floats of different geometries and topologies is presented. The floats can be truncated cylinder or cylinder with moonpool buoys and have different outer radius, inner radius, draft, mass and can be connected to linear generators of different power take-off constants. The model is implemented into a numerical code where the input is measured time-series of irregular waves. After validation against benchmark software, the model is used to study optimal configurations of wave energy arrays consisting of different wave energy devices. It is shown that the total power absorption can be improved if the wave energy array consists of devices of different dimensions, and that a higher power-to-mass ratio can be achieved.
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| 5. |
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| 6. |
- Lindroth [formerly Tyrberg], Simon, 1979-
(författare)
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Buoy and Generator Interaction with Ocean Waves : Studies of a Wave Energy Conversion System
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- On March 13th, 2006, the Division of Electricity at Uppsala University deployed its first wave energy converter, L1, in the ocean southwest of Lysekil. L1 consisted of a buoy at the surface, connected through a line to a linear generator on the seabed. Since the deployment, continuous investigations of how L1 works in the waves have been conducted, and several additional wave energy converters have been deployed. This thesis is based on ten publications, which focus on different aspects of the interaction between wave, buoy, and generator. In order to evaluate different measurement systems, the motion of the buoy was measured optically and using accelerometers, and compared to measurements of the motion of the movable part of the generator - the translator. These measurements were found to correlate well. Simulations of buoy and translator motion were found to match the measured values. The variation of performance of L1 with changing water levels, wave heights, and spectral shapes was also investigated. Performance is here defined as the ratio of absorbed power to incoming power. It was found that the performance decreases for large wave heights. This is in accordance with the theoretical predictions, since the area for which the stator and the translator overlap decreases for large translator motions. Shifting water levels were predicted to have the same effect, but this could not be seen as clearly. The width of the wave energy spectrum has been proposed by some as a factor that also affects the performance of a wave energy converter, for a set wave height and period. Therefore the relation between performance and several different parameters for spectral width was investigated. It was found that some of the parameters were in fact correlated to performance, but that the correlation was not very strong. As a background on ocean measurements in wave energy, a thorough literature review was conducted. It turns out that the Lysekil project is one of quite few projects that have published descriptions of on-site wave energy measurements.
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| 7. |
- Mathern, Alexandre, 1986, et al.
(författare)
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Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends
- 2021
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 14:7
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Forskningsöversikt (refereegranskat)abstract
- Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.
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| 8. |
- Petersson, Jesper, 1974, et al.
(författare)
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Defend, Retreat and Attack: Urban Waters and Valuation Practices
- 2022
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Ingår i: Water Alternatives. - : Water Alternatives Association. - 1965-0175. ; 15:1, s. 175-192
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Tidskriftsartikel (refereegranskat)abstract
- This paper explores the river landscapes and concomitant values resulting from tensions between flood management and visions of a River City. The aim is to contribute to an understanding of the management of urban waters as valuation practices. We regard valuation practices as co-constitutive of current and future river landscapes. Sweden’s second-largest city, Gothenburg, is located next to the sea, and the Göta River, Sweden’s largest water system, runs through it. Our empirical focus is on how this city approaches increasing risks of flooding. We explore three approaches that have been formulated in relation to flood management: defend, retreat and attack. We ask how these approaches are applied in the management of Göta River flooding and in the city’s vision of a future Gothenburg that embraces the river as a genuinely positive aspect of urban life. We present the case as a journey that takes us upstream from the river’s sea inlet port and through Gothenburg. During our kilometre by kilometre journey, the river’s appearance shifts. The varied river landscape mirrors the diversity in how its waters are valuated, both historically and in present times. The perception of urban waters is shaped by practices of valuation. These valuations are generative. They connect the value of water to other entities, actors, plans, activities and buildings, and they are thus key to the river landscapes that will eventually be realised. By way of conclusion, we identify a number of governance challenges that are particularly relevant to urban rivers.
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| 9. |
- Remouit, Flore, 1988-
(författare)
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Automation of underwater operations on wave energy converters using remotely operated vehicles
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the last fifteen years, the Division of Electricity at Uppsala University has been developing a wave energy converter (WEC) concept. The concept is based on a point-absorbing buoy with a directly driven linear generator placed on the seabed. Several units are connected to a marine substation, whose role is to collect and smooth the power absorbed from the waves and then bring it to the shore through one single cable.A big challenge in the project is to reduce the costs related to the deployment and maintenance of the WECs and substation. Currently, those operations are performed by divers, which is costly and entail considerable risks. A possibility is to replace divers with automated solutions using small robots called remotely operated vehicles (ROVs). This PhD thesis proposes and analyses a method for deployment and maintenance of underwater devices with no use of diving operations.Existing ROVs need additional modules and equipment in order to carry out operations with the required force and precision. Typical missions are inspection, shackles or slings removal, valve closing, and cable connection. The latter demands especially high precision in the positioning: 5 mm in distance and 5◦ in heading angle. In addition, this operation involves forces up to 200 N. This combination power-precision is not reached by existing ROVs. This PhD thesis presents a positioning system for underwater robot to enable autonomous positioning of the vehicle before cable connection.The positioning system is composed of two green lasers and a monocular camera, and is based on image processing. Experimental results from laboratory testing show that the mean absolute error in distance measurement is as low as 6 mm at 0.7 m from the target, whereas the heading is minimized to 2◦. The computational time for the image processing is 13.6 ms per image, meaning the possibility of a 30 Hz measurement system. Used together with a closed-loop path-following unit, this positioning system can support autonomous docking. This PhD thesis presents the model of an autopilot and results from docking simulations, showing the performance of the positioning system used in closed-loop.
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| 10. |
- Shahroozi, Zahra, et al.
(författare)
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Considerations on prediction horizon and dissipative losses for wave energy converters
- 2021
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Ingår i: IET Renewable Power Generation. - : Institution of Engineering and Technology. - 1752-1416 .- 1752-1424. ; 15:14, s. 3434-3458
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Tidskriftsartikel (refereegranskat)abstract
- The non-causal optimal control law for wave energy converters leads to a requirement of predicting waves and wave forces over a future horizon. Using examples of generic body shapes and oscillation modes, we show through computations of the velocity reference trajectory how the length of prediction horizon required to reach the maximum power output depends on the level of dissipative losses in the conversion chain. The sensitivity to noise is discussed, and so is the use of filtering to improve performance when the available prediction horizon is short or predictions are inaccurate. Considerations are also made for amplitude constraints and other effects encountered in a real system. With realistic assumptions for the level of dissipative losses, results indicate that the prediction horizon needed to approach the maximum achievable power output for real systems ranges from only a few seconds up to about half a wave period, which is shorter than has generally been assumed earlier.
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| 11. |
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| 12. |
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| 13. |
- Shahroozi, Zahra
(författare)
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Prediction horizon requirement in control and extreme load analyses for survivability : Advancements to improve the performance of wave energy technologies
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of wave energy converters (WECs) is to ensure reliable electricity production at a competitive cost. Two challenges to achieving this are ensuring an efficient energy conversion and offshore survivability. This thesis work is structured in three different sections: Control and maximum power optimization, forces and dynamics analysis in extreme wave conditions, and statistical modeling of extreme loads in reliability analysis. The need for prediction and future knowledge of waves and wave forces is essential due to the non-causality of the optimal velocity relation for wave energy converters. Using generic concepts and modes of motion, the sensitivity of the prediction horizon to various parameters encountered in a real system is elaborated. The results show that through a realistic assumption of the dissipative losses, only a few seconds to about half a wave cycle is sufficient to predict the required future knowledge for the aim of maximizing the power absorption. The results of a 1:30 scaled wave tank experiment are used to assess the line force and dynamic behaviour of a WEC during extreme wave events. Within the comparison of different wave type representations, i.e. irregular, regular and focused waves, of the same sea state, the results show that not all the wave types deliver the same maximum line forces. As a strategy of mitigating the line forces during extreme wave events, changing the power take-off (PTO) damping may be employed. With consideration of the whole PTO range, the results indicate an optimum damping value for each sea state in which the smallest maximum line force is obtained. Although wave breaking slamming and end-stop spring compression lead to high peak line forces, it is possible that they level out due to the overtopping effect. Waves with a long wavelength result in large surge motion and consequently higher and more damaging forces. On the investigation of reliability assessment of the wave energy converter systems, computing the return period of the extreme forces is crucial. Using force measurement force data gathered at the west coast of Sweden, the extreme forces are statistically modelled with the peak-over-threshold method. Then, the return level of the extreme forces over 20 years for the calm season of the year is computed.
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| 14. |
- Shahroozi, Zahra, 1992-
(författare)
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Survivability control using data-driven approaches and reliability analysis for wave energy converters
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wave energy, with five times the energy density of wind and ten times the power density of solar, offers a compelling carbon-free electricity solution. Despite its advantages, ongoing debates surround the reliability and economic feasibility of wave energy converters (WECs). To address these challenges, this doctoral thesis is divided into four integral parts, focusing on optimizing the prediction horizon for power maximization, analyzing extreme waves' impact on system dynamics, ensuring reliability, and enhancing survivability in WECs.Part I emphasizes the critical importance of the prediction horizon for maximal power absorption in wave energy conversion. Using generic body shapes and modes, it explores the effect of dissipative losses, noise, filtering, amplitude constraints, and real-world wave parameters on the prediction horizon. Findings suggest achieving optimal power output may be possible with a relatively short prediction horizon, challenging traditional assumptions.Part II shifts focus to WEC system dynamics, analyzing extreme load scenarios. Based on a 1:30 scaled wave tank experiment, it establishes a robust experimental foundation, extending into numerical assessment of the WEC. Results underscore the importance of damping to alleviate peak forces. Investigating various wave representations highlights conservative characteristics of irregular waves, crucial for WEC design in extreme sea conditions.Part III explores the computational intricacies of environmental design load cases and fatigue analyses for critical mechanical components of the WEC. The analysis is conducted for hourly sea state damage and equivalent two-million-cycle loads. Finally, a comparison of safety factors between the ultimate limit state and fatigue limit state unfolds, illustrating the predominant influence of the ultimate limit state on point-absorber WEC design.Part IV, centers on elevating survivability strategies for WECs in extreme wave conditions. Three distinct controller system approaches leverage neural networks to predict and minimize the line force. Distinct variations emerge in each approach, spanning from rapid detection of optimal damping to integrating advanced neural network architectures into the control system with feedback. The incorporation of a controller system, refined through experimental data, showcases decreases in the line force, providing a practical mechanism for real-time force alleviation.This thesis aims to contribute uniquely to the goal of advancing wave energy conversion technology through extensive exploration.
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| 15. |
- Strömstedt, Erland, 1972-
(författare)
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Submerged Transmission in Wave Energy Converters : Full Scale In-Situ Experimental Measurements
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Different wave power technologies are in development around the world in different stages of prototype testing. So far only a few devices have been deployed offshore at full scale for extended periods of time. Little data is published about how these different devices perform.This thesis presents results from experiments with the full-scale offshore wave energy converters at the Lysekil research site on the Swedish west coast. The theories, experiments, measurements, performance evaluations and developments of the submerged transmission in the direct driven permanent magnet linear generator are in focus. The reciprocating submerged transmission fulfills the purpose of transmitting the absorbed mechanical wave energy through the capsule wall into the generator, while preventing the seawater from entering the capsule and reducing the life time of the converter.A measuring system with seven laser triangulation sensors has been developed to measure small relative displacements between piston rod and seal housing in the submerged transmission with excellent accuracy for the purpose of evaluating both functional behavior and successive wear in-situ. A method for calculating relative tilt angles, azimuth angles, differential tilt angles, and successive wear in the submerged transmission has been developed. Additional sensors systems have been installed in the converter enabling correlation and a thorough investigation into the operating conditions of the transmission and the converter. The thesis presents unique results from the measurements. A data acquisition system transmits the signals from the converter on the seabed to an onshore measuring station. Results are presented in time-, frequency- and the time-frequency domain.The results have given important information for further development of the submerged transmission, which is important to the survivability of the system. The thesis describes the status of research, and is a step that may influence future designs of wave energy devices for reaching survivability and a cost-effective renewable energy system.
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| 16. |
- Svensson, Olle, 1967-
(författare)
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Experimental results from the Lysekil Wave Power Research Site
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents how experimental results, from wave power research performed offshore at the Lysekil research site, were obtained. The data were used to verify theoretical models as well as evaluate the feasibility of wave power as a future sustainable energy source.The first experiments carried out at the research site was the measurement of the force in a line where one end was connected to a buoy with a diameter of 3 m and the other end to a set of springs with limited stroke length. The system is exposed to high peak forces compared to average forces. The maximum measured force in the line, when the buoy motion is limited by a stiff stopper rope is ten times the average force in that particular sea state.The experiment performed on the first wave energy converter tested at the Lysekil Research Site is described. The infrastructure of the site is presented where the central connection point is the measuring station. The key finding is that it is possible to transform the motions of ocean waves into electrical energy and distribute it to land.Many wave energy converters must be interconnected if large amounts of energy are to be harvested from the waves. The first submerged substation intended for aggregation of energy from wave power converters is described, with focus on the measurement and control system placed inside the substation. During this experiment period the generators were equipped with many different sensors; these measurements are explained in the thesis.The system that aggregates power from the studied wave energy converter is regularly exposed to peak power of up to 20 times the maximum average output from the converter.Vertical and horizontal movement of the buoy has been measured in different ways. The result is that the vertical displacement of the buoy can be measured with a simple accelerometer circuit but it is much more complicated to measure the horizontal displacement. A special method for measuring the horizontal displacement has been implemented by measuring the strain in the enclosure and the force in the line.
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| 17. |
- Wendt, Fabian et al, et al.
(författare)
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International Energy Agency Ocean Energy Systems Task 10 Wave Energy Converter Modeling Verification and Validation
- 2017
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Ingår i: The European Wave and Tidal Conference EWTEC 2017.
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Konferensbidrag (refereegranskat)abstract
- This is the first joint reference paper for the OceanEnergy Systems (OES) Task 10 Wave Energy Converter modelingverification and validation group. The group is establishedunder the OES Energy Technology Network program under theInternational Energy Agency. OES was founded in 2001 andTask 10 was proposed by Bob Thresher (National RenewableEnergy Laboratory) in 2015 and approved by the OES ExecutiveCommittee EXCO in 2016. The kickoff workshop took place inSeptember 2016, wherein the initial baseline task was defined.Experience from similar offshore wind validation/verification projects (OC3-OC5 conducted within the International Energy Agency Wind Task 30) [1], [2] showed that a simple test case would help the initial cooperation to present results in a comparable way. A heaving sphere was chosen as the first test case. The team of project participants simulated different numerical experiments, such as heave decay tests and regular and irregular wave cases. The simulation results are presented and discussed in this paper.
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| 18. |
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| 19. |
- Wu, Jinming, et al.
(författare)
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Performance analysis of solo Duck wave energy converter arrays under motion constraints
- 2017
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 139, s. 155-169
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies the power capture performance of solo Duck wave energy converter (WEC) arrays. The barrier function method combined with a quasi-Newton BFGS optimization algorithm is applied to find the maximum captured power of the array when the Ducks are under motion constraints. Based on this optimized maximum captured power, the effects of separation distance, wave period, incident wave direction and Duck width on the array performance are investigated. For the two Ducks array, results show that the alternative constructive and destructive interaction stripes in the contour plot of the q-factor variation with non-dimensional separation distance are resulted from the diffracted wave pattern from each Duck, and the hydrodynamic interaction strength is reduced when constraints affect the performance. For the three Ducks array, the middle Duck shows larger variability of captured power than the side Ducks due to experiencing double in phase diffracted wave from the side ones. The captured power of the solo Duck WEC array is sensitive to incident wave direction, and arrays with Ducks of smaller width are found to have better performance in power capture efficiency.
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| 20. |
- Ahrné, Karin, et al.
(författare)
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Tillstånd och trender för arter och deras livsmiljöer – rödlistade arter i Sverige 2015
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- 2015 års upplaga av den svenska rödlistan är den fjärde i ordningen. Den är baserad på IUCN:s rödlistningskriterier och revideras vart femte år. I rödlistan bedöms risken som enskilda arter av djur, växter och svampar löper att försvinna från Sverige. Bedömningen utförs av ArtDatabankens medarbetare i samverkan med över 100 externa experter, indelade i 14 expertkommittéer för olika organismgrupper. Under arbetet med 2015 års rödlista har tillstånd och trender bedömts för 21 600 arter och 1 318 lägre taxa (apomiktiska arter, underarter och varieteter), sammanlagt ca 22 900 taxa. Av de bedömda arterna klassificerades 2 029 som hotade (kategorierna CR, EN och VU) och 4 273 som rödlistade (inkluderar även kategorierna NT, RE och DD). Förhållandet mellan antalet rödlistade och antalet bedömda arter ar 19,8 %, vilket är ungefär samma värde som 2010 och 2005. I denna rapport jämförs antalet och andelen rödlistade arter mellan olika organismgrupper, biotoper, substrat och påverkansfaktorer. Texten ar indelad i en allmän del och åtta kapitel inriktade på olika landskapstyper. Landskapstyperna utgör en grov indelning av landets miljöer enligt följande kategorier: Skog, Jordbrukslandskap, Urbana miljöer, Fjäll, Våtmarker, Sötvatten, Havsstränder och Havsmiljöer. Skogen och jordbrukslandskapet är de artrikaste landskapstyperna med 1 800 respektive 1 400 arter som har en stark anknytning dit, och ytterligare flera hundra arter som förekommer där mer sporadiskt. De faktorer som påverkar flest rödlistade arter i Sverige är skogsavverkning och igenväxning, som båda utgör ett hot mot vardera ca 30 % av de rödlistade arterna. Avverkning minskar arealen av skog där naturliga strukturer och naturlig dynamik upprätthålls, och den orsakar därmed förlust av livsmiljöer. Igenväxning orsakas av ett antal faktorer, bland annat upphörande hävd (bete och slåtter), gödsling, trädplantering och brist på naturliga störningsregimer som t.ex. regelbundna översvämningar kring vattendrag och sjöar. Andra viktiga påverkansfaktorer är fiske, torrläggning av våtmarker, tillbakagång hos värdarter (främst alm och ask som drabbats av invasiva svampsjukdomar), klimatförändringar och konkurrens från invasiva arter. IUCN:s rödlisteindex beräknas för ett urval av de bedömda organismgrupperna. Rödlisteindex visar att skillnaderna mellan rödlistorna från 2000, 2005, 2010 och 2015 är små. Ett par undantag finns dock. Groddjur och stora däggdjur har fått en något förbättrad situation sedan 2000. Totalt förefaller det ändå som att trycket mot Sveriges artstock har förblivit relativt konstant under de senaste 15 åren.
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| 21. |
- Haaf, Ezra, 1985, et al.
(författare)
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Physiographic and climatic controls on regional groundwater dynamics
- 2020
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Ingår i: Water Resources Research. - 0043-1397 .- 1944-7973. ; 56:10
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Tidskriftsartikel (refereegranskat)abstract
- The main goal of this study is to explore whether the ideas established by surface water hydrologists in the context of “PUB” (predictions in ungauged basins) can be useful in hydrogeology. The concrete question is whether it is possible to create predictive models for groundwater systems with no or few observations based on knowledge derived from similar groundwater systems which are well‐observed. To do so, this study analyses the relationship between temporal dynamics of groundwater levels and climatic and physiographic characteristics. The analysis is based on data from 341 wells in Southern Germany with ten‐year daily groundwater hydrographs. Observation wells are used in confined and unconfined sand and gravel aquifers from narrow mountainous valleys as well as more extensive lowland alluvial aquifers. Groundwater dynamics at each location are summarized with 46 indices describing features of groundwater hydrographs. Besides borehole log‐derived geologic information, local and regional morphologic characteristics as well as topography‐derived boundary and climatic descriptors were derived for each well. Regression relationships were established by mining the data for associations between dynamics and descriptors with forward stepwise regression at a confidence level >95%. The most important predictors are geology and boundary conditions and secondarily, climate, as well as some topographic features, such as regional convergence. The multiple regression models are in general agreement with process understanding linked to groundwater dynamics in unconfined aquifers. This systematic investigation suggests that statistical regionalization of groundwater dynamics in ungauged aquifers based on map‐derived physiographic and climatic controls may be feasible.
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| 22. |
- Heudorfer, B., et al.
(författare)
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Index-Based Characterization and Quantification of Groundwater Dynamics
- 2019
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Ingår i: Water Resources Research. - 0043-1397 .- 1944-7973. ; 55:7, s. 5575-5592
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Tidskriftsartikel (refereegranskat)abstract
- Time series of groundwater head measurements serve as a primary source of information on groundwater systems. In different groundwater systems, and across several scales, we observe a multitude of patterns in groundwater time series, resulting from complex hydrogeological setups. Unlike in surface hydrology, there is no generalized classification to categorize and quantify the dynamics in groundwater time series. This leads to a lack of tools that could help us disentangle the information contained in groundwater time series in a systematic way. To approach such a classification, we present a principle for organization to qualitatively describe and to quantify groundwater dynamics in a nonredundant and data efficient way. We devise a descriptive typology of groundwater dynamics and assign quantitative measures, mathematically expressing these dynamics. Based on an extensive data set of daily groundwater hydrographs from central Europe, we analyze the relationship between indices and typology based on principal component analysis. The principal component analysis is also used to investigate and discuss redundancy, that is, indices expressing similar information content of hydrographs. Further, the indices' sensitivity to measurement interval and length of the overall observed period is investigated. Finally, a case study demonstrates the potential of the typology and index approach to link groundwater dynamics to the underlying hydrogeological process controls. The tools provided for characterization and quantification of groundwater dynamics should improve future efforts of groundwater classification and prediction in ungauged aquifers and other applications. ©2019. The Authors.
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| 23. |
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| 24. |
- Petersson, Jesper, 1974
(författare)
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Blurring the shoreline: De- and re-infrastructuring and the changing colors of European flood policy
- 2021
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Ingår i: Environment and Planning E: Nature and Space. - : SAGE Publications. - 2514-8494 .- 2514-8494 .- 2514-8486. ; 4:2, s. 623-644
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Tidskriftsartikel (refereegranskat)abstract
- This paper provides a genealogy of the emergence of a common EU flood policy, including the scope and direction of this policy. Noticing how EU policy proposes green infrastructure (associated with using nature as a buffer zone in managing floods) as an alternative to grey infrastructure (implying fixed installations of concrete and cement), this paper adopts the theoretical lens of the so-called infrastructural turn, which advocates a relational investigation of infrastructure. By engaging this approach, the paper shows how flood infrastructure can contain very different compositions of (unruly) water and (settled) land. A narrative of a historically strong focus on guarding society from the powerful forces of nature through a fixed line of defense is increasingly giving way to more muddy states—quite literally—where society is expected to learn to live with flooding and show ecological consideration. To capture the EU’s, and especially the European Commission’s efforts to establish a pan-European flood infrastructure that accommodates this turn, the concepts of de- and re-infrastructuring are developed. These concepts act as heuristic devices to capture how policy performs some combinations between water and land as constituting an attractive and functional flood infrastructure, but constitutes other infrastructural relations of the aquatic and the terrestrial as undesirable and, hence, as malfunctioning. This performative act of distinguishing between what constitutes “good and proper” versus “bad and undesirable” infrastructure is referred to as a politics of infrastructure.
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| 25. |
- Pfeffer, Julia, et al.
(författare)
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Evaluating surface and subsurface water storage variations at small time and space scales from relative gravity measurements in semiarid Niger
- 2013
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Ingår i: Water Resources Research. - : American Geophysical Union (AGU). - 0043-1397 .- 1944-7973. ; 49:6, s. 3276-3291
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Tidskriftsartikel (refereegranskat)abstract
- The acquisition of reliable data sets representative of hydrological regimes and their variations is a critical concern for water resource assessment. For the subsurface, traditional approaches based on probe measurements, core analysis, and well data can be laborious, expensive, and highly intrusive, while only yielding sparse data sets. For this study, an innovative field survey, merging relative microgravimetry, magnetic resonance soundings, and hydrological measurements, was conducted to evaluate both surface and subsurface water storage variations in a semiarid Sahelian area. The instrumental setup was implemented in the lower part of a typical hillslope feeding to a temporary pond. Weekly measurements were carried out using relative spring gravimeters during 3 months of the rainy season in 2009 over a 350 × 500 m2 network of 12 microgravity stations. Gravity variations of small to medium amplitude (≤220 nm s-2) were measured with accuracies better than 50 nm s-2, revealing significant variations of the water storage at small time (from 1 week up to 3 months) and space (from a couple of meters up to a few hundred meters) scales. Consistent spatial organization of the water storage variations were detected, suggesting high infiltration at the outlet of a small gully. The comparison with hydrological measurements and magnetic resonance soundings involved that most of the microgravity variations came from the heterogeneity in the vadose zone. The results highlight the potential of time lapse microgravity surveys for detecting intraseasonal water storage variations and providing rich space-time data sets for process investigation or hydrological model calibration/ evaluation.
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