| 1. |
- Baresel, Christian, 1975-
(författare)
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Environmental management of water systems under uncertainty
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hydrological drainage/river basins constitute highly heterogeneous systems of coupled natural and anthropogenic water and pollutant flows across political, national and international boundaries. These flows need to be appropriately understood, quantified and communicated to stakeholders, in order to appropriately guide environmental water system management. In this thesis, various uncertainties about water and pollutant flows in drainage/river basins and their implications for effective and efficient water pollution abatement are investigated, in particular for mine-related heavy metal loadings in the Swedish Dalälven River basin and for nitrogen loadings in the Swedish Norrström drainage basin. Economic cost-minimization modeling is used to investigate the implications of pollutant load uncertainties for the cost-efficiency of catchment-scale abatement of water pollution. Results indicate that effective and efficient pollution abatement requires explicit consideration of uncertainties about pollution sources, diffuse contributions of the subsurface water system to downstream pollutant observations in surface waters, and downstream effects of different possible measures to reduce water pollution. In many cases, downstream load abatement measures must be used, in addition to source abatement, in order to reduce not only expected, but also uncertainties around expected pollutant loads. Effective and efficient environmental management of water systems must generally also consider the entire catchments of these systems, rather than focusing only on discrete pollutant sources. The thesis presents some relatively simple, catchment-scale pollutant flow analysis tools that may be used to decrease uncertainties about unmonitored water and pollutant flows and subsurface pollutant accumulation-depletion and diffuse loading to downstream waters.
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| 2. |
- Ameli, Ali A., et al.
(författare)
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Primary weathering rates, water transit times, and concentration-discharge relations : A theoretical analysis for the critical zone
- 2017
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Ingår i: Water resources research. - : AMER GEOPHYSICAL UNION. - 0043-1397 .- 1944-7973. ; 53:1, s. 942-960
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Tidskriftsartikel (refereegranskat)abstract
- 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 CeqRmax 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 CeqRmax decreases, the concentration in the critical zone and stream become less dependent on groundwater age (or transit time).
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| 3. |
- Amvrosiadi, Nino
(författare)
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The value of experimental data and modelling for exploration of hydrological functioning: The case of a till hillslope
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Successfully modeling one system response (e.g. hydrograph or solute transport) sometimes gives the false sense of well-characterizing the modeled system. This is partly because of the well-known equifinality issue; during the calibration process multiple parameter combinations can produce similarly good results. One step forward towards a better-defined system is using measured (at relevant scale) values for the model parameters, as well as using multiple conditions to constrain the model.But when not enough, or relevant, field measurements are available, virtual experiments (VE’s) can be used as a supplementary method to model calibration. The advantage of VE’s over model calibration is that they can also be used to explore assumptions both on the system hydrological processes, and on the model structure.One goal of this study was to utilize both field measurements and models for better characterization of the S-transect hillslope, located in Västrabäcken catchment, Northern Sweden. This included (a) characteristics in space: system vertical boundaries, hydraulic parameters, pore water velocity distribution, spatial correlation of flowpaths, soil water retention properties; (b) characteristic of system’s dynamic behavior: storage – discharge relationship, transit time distribution, turnover time; and (c) outputs’ sensitivity to external forcing, and to small scale structure assumptions. The second goal was to comment on the value of field measurements and virtual experiments for extracting information about the studied system.An intensely monitored study hillslope was chosen for this work. Although the hillslope has already been the subject of multiple field and modelling studies, there are still open questions regarding the characteristics listed above. The models used were the Vertical Equilibrium Model (VEM), and the Multiple Interacting Pathways (MIPs) model.It was found that the hillslope was well connected; from the near-stream areas up to the water divide the storage – discharge relationship could be described as an exponential function. Also, the dynamic storage (which controls the hydrograph dynamics) was much smaller comparing to the total hillslope storage. The unsaturated soil storage was found to be more sensitive to water table positions than vertical flux magnitude. The dynamic condition of external forcing (precipitation and evapotranspiration) affected the transit time distribution (TTD) shape. And, opposite to expectations, TTD was not sensitive to micro-scale structural assumptions tested here.
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| 4. |
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| 5. |
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| 6. |
- Beven, Keith
(författare)
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A manifesto for the equifinality thesis
- 2006
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 320:1-2, s. 18-36
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Tidskriftsartikel (refereegranskat)abstract
- This essay discusses some of the issues involved in the identification and predictions of hydrological models given some calibration data. The reasons for the incompleteness of traditional calibration methods are discussed. The argument is made that the potential for multiple acceptable models as representations of hydrological and other environmental systems (the equifinality thesis) should be given more serious consideration than hitherto. It proposes some techniques for an extended GLUE methodology to make it more rigorous and outlines some of the research issues still to be resolved. (c) 2005 Elsevier Ltd All rights reserved.
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| 7. |
- Beven, Keith
(författare)
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Advice to a young hydrologist
- 2016
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Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 30:20, s. 3578-3582
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Beven, Keith
(författare)
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Causal models as multiple working hypotheses about environmental processes
- 2012
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Ingår i: Comptes rendus Geoscience. - : Elsevier BV. - 1631-0713 .- 1778-7025. ; 344:2, s. 77-88
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Tidskriftsartikel (refereegranskat)abstract
- The environmental modeller faces a dilemma. Science often demands that more and more process representations are incorporated into models (particularly to avoid the possibility of making missing process errors in predicting future response). Testing the causal representations in environmental models (as multiple working hypotheses about the functioning of environmental systems) then depends on specifying boundary conditions and model parameters adequately. This will always be difficult in applications to a real system because of the heterogeneities, non-stationarities, complexities and epistemic uncertainties inherent in environmental prediction. Thus, it can be difficult to define the information content of a data set used in model evaluation and any consequent measures of belief or verisimilitude. A limit of acceptability approach to model evaluation is suggested as a way of testing models, implying that thought is required to define critical experiments that will allow models as hypotheses to be adequately differentiated. (C) 2012 Published by Elsevier Masson SAS on behalf of Academie des sciences.
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| 9. |
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| 10. |
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| 11. |
- Beven, Keith, et al.
(författare)
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Concepts of Information Content and Likelihood in Parameter Calibration for Hydrological Simulation Models
- 2015
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Ingår i: Journal of hydrologic engineering. - 1084-0699 .- 1943-5584. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- There remains a great deal of uncertainty about uncertainty estimation in hydrological modeling. Given that hydrology is still a subject limited by the available measurement techniques, it does not appear that the issue of epistemic error in hydrological data will go away for the foreseeable future, and it may be necessary to find a way to allow for robust model conditioning and more subjective treatments of potential epistemic errors in prediction. In this paper an attempt is made to analyze how this is the result of the epistemic uncertainties inherent in the hydrological modeling process and their impact on model conditioning and hypothesis testing. Some ideas are proposed about how to deal with assessing the information in hydrological data and how it might influence model conditioning based on hydrological reasoning, with an application to rainfall-runoff modeling of a catchment in northern England, where inconsistent data for some events can introduce disinformation into the model conditioning process. A methodology is presented to make an assessment of the relative information content of calibration data before running a model that can then inform the evaluation of model runs and resulting prediction uncertainties.
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| 12. |
- Beven, Keith, et al.
(författare)
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Epistemic uncertainties and natural hazard risk assessment - Part 1 : A review of different natural hazard areas
- 2018
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Ingår i: Natural hazards and earth system sciences. - : COPERNICUS GESELLSCHAFT MBH. - 1561-8633 .- 1684-9981. ; 18:10, s. 2741-2768
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Forskningsöversikt (refereegranskat)abstract
- This paper discusses how epistemic uncertainties are currently considered in the most widely occurring natural hazard areas, including floods, landslides and debris flows, dam safety, droughts, earthquakes, tsunamis, volcanic ash clouds and pyroclastic flows, and wind storms. Our aim is to provide an overview of the types of epistemic uncertainty in the analysis of these natural hazards and to discuss how they have been treated so far to bring out some commonalities and differences. The breadth of our study makes it difficult to go into great detail on each aspect covered here; hence the focus lies on providing an overview and on citing key literature. We find that in current probabilistic approaches to the problem, uncertainties are all too often treated as if, at some fundamental level, they are aleatory in nature. This can be a tempting choice when knowledge of more complex structures is difficult to determine but not acknowledging the epistemic nature of many sources of uncertainty will compromise any risk analysis. We do not imply that probabilistic uncertainty estimation necessarily ignores the epistemic nature of uncertainties in natural hazards; expert elicitation for example can be set within a probabilistic framework to do just that. However, we suggest that the use of simple aleatory distributional models, common in current practice, will underestimate the potential variability in assessing hazards, consequences, and risks. A commonality across all approaches is that every analysis is necessarily conditional on the assumptions made about the nature of the sources of epistemic uncertainty. It is therefore important to record the assumptions made and to evaluate their impact on the uncertainty estimate. Additional guidelines for good practice based on this review are suggested in the companion paper (Part 2).
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| 13. |
- Beven, Keith, et al.
(författare)
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Epistemic uncertainties and natural hazard risk assessment - Part 2 : What should constitute good practice?
- 2018
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Ingår i: Natural hazards and earth system sciences. - : COPERNICUS GESELLSCHAFT MBH. - 1561-8633 .- 1684-9981. ; 18:10, s. 2769-2783
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Tidskriftsartikel (refereegranskat)abstract
- Part 1 of this paper has discussed the uncertainties arising from gaps in knowledge or limited understanding of the processes involved in different natural hazard areas. Such deficits may include uncertainties about frequencies, process representations, parameters, present and future boundary conditions, consequences and impacts, and the meaning of observations in evaluating simulation models. These are the epistemic uncertainties that can be difficult to constrain, especially in terms of event or scenario probabilities, even as elicited probabilities rationalized on the basis of expert judgements. This paper reviews the issues raised by trying to quantify the effects of epistemic uncertainties. Such scientific uncertainties might have significant influence on decisions made, say, for risk management, so it is important to examine the sensitivity of such decisions to different feasible sets of assumptions, to communicate the meaning of associated uncertainty estimates, and to provide an audit trail for the analysis. A conceptual framework for good practice in dealing with epistemic uncertainties is outlined and the implications of applying the principles to natural hazard assessments are discussed. Six stages are recognized, with recommendations at each stage as follows: (1) framing the analysis, preferably with input from potential users; (2) evaluating the available data for epistemic uncertainties, especially when they might lead to inconsistencies; (3) eliciting information on sources of uncertainty from experts; (4) defining a workflow that will give reliable and accurate results; (5) assessing robustness to uncertainty, including the impact on any decisions that are dependent on the analysis; and (6) communicating the findings and meaning of the analysis to potential users, stakeholders, and decision makers. Visualizations are helpful in conveying the nature of the uncertainty outputs, while recognizing that the deeper epistemic uncertainties might not be readily amenable to visualizations.
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| 14. |
- Beven, Keith
(författare)
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Facets of uncertainty : epistemic uncertainty, non-stationarity, likelihood, hypothesis testing, and communication
- 2016
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 61:9, s. 1652-1665
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a discussion of some of the issues associated with the multiple sources of uncertainty and non-stationarity in the analysis and modelling of hydrological systems. Different forms of aleatory, epistemic, semantic, and ontological uncertainty are defined. The potential for epistemic uncertainties to induce disinformation in calibration data and arbitrary non-stationarities in model error characteristics, and surprises in predicting the future, are discussed in the context of other forms of non-stationarity. It is suggested that a condition tree is used to be explicit about the assumptions that underlie any assessment of uncertainty. This also provides an audit trail for providing evidence to decision makers.
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| 15. |
- Beven, Keith
(författare)
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‘Here we have a system in which liquid water is moving; let's just get at the physics of it’ (Penman 1965)
- 2014
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Ingår i: Hydrology Research. - : IWA Publishing. - 2224-7955 .- 0029-1277. ; 45:6, s. 727-736
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Tidskriftsartikel (refereegranskat)abstract
- This paper is based on the 2012 Penman Lecture delivered at the 11th National Symposium of the British Hydrological Society. The title is taken from a 1965 interview by Howard Penman when hydrological modelling was just really starting. In the period since then, the idea that we might easily move towards ‘physically based’ representations of hydrological processes has proven problematic. It is argued that this might best be done within a hypotheses testing framework, where the hypotheses are the model representations of processes over some discrete elements of a catchment, integrating the small-scale variability within those elements. This might still require some distribution function to reflect that variability, since the extremes of the variability might be important in controlling the response. Hypotheses will need to be formulated that reflect the interaction of the water flow pathways and the biota. Testing of those hypotheses will require a proper account of the uncertainties inherent in the study of hydrological systems, including a recognition that many sources of uncertainty are epistemic in nature rather than simple random variability. Such uncertainties will only be significantly reduced by the development of new measurement techniques that provide useful information at the element scales of interest.
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| 16. |
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| 17. |
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| 18. |
- Beven, Keith J, et al.
(författare)
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Comment on “Hydrological forecasting uncertainty assessment: Incoherence of the GLUE methodology” by Pietro Mantovan and Ezio Todini
- 2007
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 338:3-4, s. 315-318
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Tidskriftsartikel (refereegranskat)abstract
- This comment is a response to the criticisms of the GLUE methodology by [Mantovan, P., Todini, E., 2006. Hydrological forecasting uncertainty assessment: Incoherence of the GLUE methodology, J. Hydrology, 2006]. In this comment it is shown that the formal Bayesian identification of models is a special case of GLUE that can be used where the modeller is prepared to make very strong assumptions about the nature of the modelling errors. For the hypothetical study of Mantovan and Todini, exact assumptions were assumed known for the formal Bayesian identification, but were then ignored in the application of GLUE to the same data. We show that a more reasonable application of GLUE to this problem using similar prior knowledge shows that gives equally coherent results to the formal Bayes identification. In real applications, subject to input and model structural error it is suggested that the coherency condition of MT06 cannot hold at the single observation level and that the choice of a formal Bayesian likelihood function may then be incoherent. In these (more interesting) cases, GLUE can be coherent in the application of likelihood measures based on blocks of data, but different choices of measures and blocks effectively represent different beliefs about the information content of data in real applications with input and model structural errors.
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| 19. |
- Beven, Keith J., et al.
(författare)
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Communicating uncertainty in flood inundation mapping : a case study
- 2015
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Ingår i: International Journal of River Basin Management. - : Informa UK Limited. - 1571-5124 .- 1814-2060. ; 13:3, s. 285-295
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Tidskriftsartikel (refereegranskat)abstract
- An important issue in taking account of uncertainty in flood inundation mapping is the communication of the meaning of the outputs from an uncertainty analysis. In part this is because uncertainty estimation in this domain is not a simple statistical problem in that it involves knowledge uncertainties as well as statistical (aleatory) uncertainties in most of the important sources of uncertainty (estimated upstream discharges, effective roughness coefficients, flood plain and channel geometries and infrastructure, choice of model, fragility of defences, etc.). Thus, assumptions are required associated with the knowledge or lack of knowledge about these different sources of uncertainty. A framework has been developed in the form of a sequence of condition trees to help define these assumptions. Since stakeholders in the process can potentially be involved in making and recording decisions about those assumptions the framework also serves as a means of communicating the assumptions. Recording the decisions also serves to provide an audit trail for later evaluation of the decisions and hence the resulting analysis. Communication can also be helped in this type of spatial problem by effective visualization techniques and a visualization tool has been developed for both a web-based service using Google Maps™ and a desktop application using the Matlab™ numerical package.
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| 20. |
- Beven, Keith J., et al.
(författare)
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GLUE : 20 years on
- 2014
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Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 28:24, s. 5897-5918
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Forskningsöversikt (refereegranskat)abstract
- This paper reviews the use of the Generalized Likelihood Uncertainty Estimation (GLUE) methodology in the 20 years since the paper by Beven and Binley in Hydrological Processes in (1992), which is now one of the most highly cited papers in hydrology. The original conception, the on-going controversy it has generated, the nature of different sources of uncertainty and the meaning of the GLUE prediction uncertainty bounds are discussed. The hydrological, rather than statistical, arguments about the nature of model and data errors and uncertainties that are the basis for GLUE are emphasized. The application of the Institute of Hydrology distributed model to the Gwy catchment at Plynlimon presented in the original paper is revisited, using a larger sample of models, a wider range of likelihood evaluations and new visualization techniques. It is concluded that there are good reasons to reject this model for that data set. This is a positive result in a research environment in that it requires improved models or data to be made available. In practice, there may be ethical issues of using outputs from models for which there is evidence for model rejection in decision making. Finally, some suggestions for what is needed in the next 20 years are provided.
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| 21. |
- Beven, Keith J., et al.
(författare)
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Hyperresolution information and hyperresolution ignorance in modelling the hydrology of the land surface
- 2015
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Ingår i: SCIENCE CHINA-EARTH SCIENCES. - : Springer Science and Business Media LLC. - 1674-7313 .- 1869-1897. ; 58:1, s. 25-35
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Tidskriftsartikel (refereegranskat)abstract
- There is a strong drive towards hyperresolution earth system models in order to resolve finer scales of motion in the atmosphere. The problem of obtaining more realistic representation of terrestrial fluxes of heat and water, however, is not just a problem of moving to hyperresolution grid scales. It is much more a question of a lack of knowledge about the parameterisation of processes at whatever grid scale is being used for a wider modelling problem. Hyperresolution grid scales cannot alone solve the problem of this hyperresolution ignorance. This paper discusses these issues in more detail with specific reference to land surface parameterisations and flood inundation models. The importance of making local hyperresolution model predictions available for evaluation by local stakeholders is stressed. It is expected that this will be a major driving force for improving model performance in the future.
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| 22. |
- Beven, Keith J., et al.
(författare)
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Modelling everything everywhere : a new approach to decision-making for water management under uncertainty
- 2012
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Ingår i: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 57, s. 124-132
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Tidskriftsartikel (refereegranskat)abstract
- 1. There are increasing demands to predict ecohydrological responses to future changes in catchments but such predictions will be inevitably uncertain because of natural variability and different sources of knowledge (epistemic) uncertainty. 2. Policy setting and decision-making should therefore reflect these inherent uncertainties in both model predictions and potential consequences. 3. This is the focus of a U.K. Natural Environment Research Council knowledge exchange project called the Catchment Change Network (CCN). The aim is to bring academics and practitioners together to define Guidelines for Good Practice in incorporating risk and uncertainty into assessments of the impacts of change. 4. Here, we assess the development of such Guidelines in the context of having catchment models of everywhere.
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| 23. |
- Beven, Keith J., et al.
(författare)
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Rethinking Concepts of Information Content of Hydrological Data to Account for Epistemic Errors
- 2014
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Ingår i: Vulnerability, Uncertainty, and Risk. - Reston, VA : American Society of Civil Engineers. - 9780784413609 ; , s. 263-272
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Konferensbidrag (refereegranskat)abstract
- There remains a great deal of uncertainty about uncertainty estimation in hydrological modelling. Given that hydrology is still a subject limited by the available measurement techniques, it does not appear that the issue of epistemic error in hydrological data will go away for the foreseeable future. It may be necessary to find a way of allowing for robust model conditioning and more subjective treatments of potential epistemic errors in model applications. In this study, we have made an attempt to analyse how this is the result of the epistemic uncertainties inherent in the hydrological modelling process and its impact on model conditioning and hypothesis testing. We propose some ideas about how to deal with assessing the information in hydrological data and how it might influence model conditioning based on hydrological reasoning, with an application to rainfall-runoff modelling of a catchment in Northern England where inconsistent data for some events can potentially introduce disinformation into the model conditioning process. A methodology is presented to make an assessment of the relative information content of calibration data before running a model that can then inform the evaluation of model runs and resulting simulation uncertainties.
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| 24. |
- Beven, Keith J., et al.
(författare)
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Struggling with Epistemic Uncertainties in Environmental Modelling of Natural Hazards
- 2014
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Ingår i: Vulnerability, Uncertainty, and Risk. - Reston, VA : American Society of Civil Engineers. - 9780784413609 ; , s. 13-22
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Konferensbidrag (refereegranskat)abstract
- Epistemic uncertainties create difficulties for the quantitative estimation of uncertainties associated with environmental models. The nature of the issues involved is discussed, particularly in how to assign likelihood values to models when the forcing data and evaluation data might both be subject to epistemic uncertainties. A case study of a rainfall-runoff model of the River Brue catchment is developed with the Generalised Likelihood Uncertainty Estimation (GLUE) methodology. Model evaluation is carried out using limits of acceptability set from considerations of the available data prior to running a model, while the errors associated with a model are treated non-parametrically for different parts of the hydrograph.
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| 25. |
- Beven, Keith J., et al.
(författare)
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The uncertainty cascade in model fusion
- 2017
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Ingår i: Geological Society Special Publication. - 0305-8719 .- 2041-4927. ; 408:1, s. 255-266
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Tidskriftsartikel (refereegranskat)abstract
- There are increasing demands in assessing the impacts of change on environmental systems to couple different model components together in a cascade, the outputs from one component providing the inputs to another with or without feedbacks in the coupling. Each model component will necessarily involve some uncertainty in its specification and simulations that can be conditioned using some observational data. Taking account of this uncertainty should result in more robust decision making and may change the nature of the decision made. The difficulty in environmental decision making is in making proper estimates of uncertainties when so many of the sources of uncertainty result from lack of knowledge (epistemic uncertainties) rather than uncertainty that can be treated as random variability (aleatory uncertainty). This is particularly the case for problems that involve cascades of model components. Examples are the use of UKCP09 climate scenarios in impact studies, flood risk assessment involving models of runoff generation and their impact on hydraulic models of flood plains, and integrated catchment management involving upstream to downstream surface and subsurface routing of water quality variables. The uncertainties are such that, even for relatively simple problems, they can result in wide ranges of potential outputs. This poses the questions that will be considered in this paper: how to take account of knowledge uncertainties in cascades of model components; and how to constrain the potential uncertainties for use in making decisions. In particular we highlight the difficulties of defining statistical likelihood functions that properly reflect the non-stationary uncertainty characteristics expected of epistemic sources of uncertainty.
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