| 1. |
- Blösch, Günter, et al.
(författare)
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Twenty-three unsolved problems in hydrology (UPH) - a community perspective
- 2019
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 64:10, s. 1141-1158
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Tidskriftsartikel (refereegranskat)abstract
- This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come.
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| 2. |
- Freer, J., et al.
(författare)
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Flood risk and uncertainty
- 2013
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Ingår i: Risk and Uncertainty Assessment for Natural Hazards. - : Cambridge University Press. - 9781139047562 - 9781107006195 ; , s. 190-233
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- IntroductionExtreme floods are among the most destructive forces of nature. Flooding accounts for a significant proportion of the total number of reported natural disasters occurring in the world (Figure 7.1a) and over the last 30 years this proportion has been increasing (Figure 7.1b). Reasons for this trend may not be clear; for each hazard there is a need to quantify whether this is an increase in the hazard itself, an increase in exposure to the hazard internationally or a change in the reporting of what constitutes a natural disaster. Internationally, the costs and scale of flooding are enormous but differ depending on the types of impact that are analysed and the databases used. Globally in 2007 it was estimated that annually 520 million people are affected by floods and that the death toll is approximately 25 000 people in any one year. Jonkman (2005) found for a study using data from 1974 to 2003 (from data maintained by the Centre for Research on the Epidemiology of Disasters in Brussels) that floods are the most significant natural disaster type in terms of the number of people affected – some 51% of the total of that period of approximately five billion people affected by natural disaster (droughts are second with 36%, and earthquakes third at 2%). However, in terms of overall estimated deaths flooding accounts for 10% of the approximately two million reported deaths associated with natural disasters over the 1974–2003 period (droughts 44% and earthquakes 27%). In monetary terms an assessment by Munich RE for the period 1980–2010 determined that at 2010 prices the losses totalled US$3000 billion from ~19 400 events with 2.275 million fatalities. Of these, hydrological catastrophes (flooding and mass movement, i.e. landslips and debris flow in this case) accounted for 24% of these monetary losses, from 35% of the total events, and 11% of the fatalities. Other categories of natural disasters included in these totals were geophysical, meteorological and climatological (NatCatSERVICE, 2011).
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| 3. |
- McDonnell, J.J., et al.
(författare)
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How old is streamwater? : Open questions in catchment transit time conceptualization, modelling and analysis
- 2010
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Ingår i: Hydrological Processes. - : John Wiley & Sons. - 0885-6087 .- 1099-1085. ; 24:12, s. 1745-1754
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Tidskriftsartikel (refereegranskat)abstract
- The time water spends travelling subsurface through a catchment to the stream network (i.e. the catchment water transit time) fundamentally describes the storage, flow pathway heterogeneity and sources of water in a catchment. The distribution of transit times reflects how catchments retain and release water and solutes that in turn set biogeochemical conditions and affect contamination release or persistence. Thus, quan- tifying the transit time distribution provides an important constraint on biogeochemical processes and catchment sensitivity to anthropogenic inputs, contamination and land-use change. Although the assumptions and limitations of past and present transit time modelling approaches have been recently reviewed (McGuire and McDonnell, 2006), there remain many fundamental research challenges for understanding how transit time can be used to quantify catchment flow processes and aid in the development and testing of rainfall–runoff models. In this Commen- tary study, we summarize what we think are the open research questions in transit time research. These thoughts come from a 3-day workshop in January 2009 at the International Atomic Energy Agency in Vienna. We attempt to lay out a roadmap for this work for the hydrological commu- nity over the next 10 years. We do this by first defining what we mean (qualitatively and quantitatively) by transit time and then organize our vision around needs in transit time theory, needs in field studies of tran- sit time and needs in rainfall – runoff modelling. Our goal in presenting this material is to encourage widespread use of transit time information in process studies to provide new insights to catchment function and to inform the structural development and testing of hydrologic models.
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| 4. |
- Kulasova, A., et al.
(författare)
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A method of computing uncertain nitrogen and phosphorus loads in a small stream from an agricultural catchment using continuous monitoring data
- 2012
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 458-459, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- A method for computing loads of total phosphorus and nitrate from a small catchment in the Czech Republic has been presented, given continuous measurements of water levels, turbidity and an ion-specific NO3--N probe together with a limited number of discharge measurements and analyses of grab samples. Given the observed variability in the observations, log-log regressions are used to convert water levels to discharge and to derive continuous estimates of total phosphorus and nitrate. Integrations to estimate loads using predicted values of the true discharges and concentrations are then carried out by a Monte Carlo method to avoid strong assumptions of independence and distribution. Coefficients of variation for the estimated monthly loads range from 5% to 23% for TP and 12-36% for NO3--N. At the annual time scales, coefficients of variation are of the order of 5% for both TP and NO3--N. The variability in the estimated annual loads between the years was, however, significantly larger than the uncertainties estimated within each year.
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| 5. |
- 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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| 6. |
- 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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| 7. |
- Davies, J., et al.
(författare)
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Comparison of a Multiple Interacting Pathways model with a classical kinematic wave subsurface flow solution
- 2012
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 57:2, s. 203-216
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Tidskriftsartikel (refereegranskat)abstract
- A discrete random particle representation of flow processes on shallow hillslopes is compared with solutions of the classical kinematic wave representation. The discrete Multiple Interacting Pathways (MIPs) model has the potential to represent the effects of complex heterogeneities and preferential flow pathways. It is shown that, under shared assumptions, the MIPs model can produce equivalent flow predictions to a standard kinematic wave realization. The MIPs model is then used to further explore the relationship between celerity and water velocity by introducing a velocity distribution, which represents the range of possible flow pathways, and therefore is representative of the nature of heterogeneity (or lack of it within a homogeneous case) within the subsurface. It is shown that, whilst flux constraints can be satisfied with a distribution of flow velocities, it can result in changes to the hydrograph. Multiple pathways also have an influence on the residence times for input increments, output increments and storage in the system.
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| 8. |
- Delsman, Joost R., et al.
(författare)
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Uncertainty estimation of end-member mixing using generalized likelihood uncertainty estimation (GLUE), applied in a lowland catchment
- 2013
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Ingår i: Water resources research. - : American Geophysical Union (AGU). - 0043-1397 .- 1944-7973. ; 49:8, s. 4792-4806
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Tidskriftsartikel (refereegranskat)abstract
- End-member mixing models have been widely used to separate the different components of a hydrograph, but their effectiveness suffers from uncertainty in both the identification of end-members and spatiotemporal variation in end-member concentrations. In this paper, we outline a procedure, based on the generalized likelihood uncertainty estimation (GLUE) framework, to more inclusively evaluate uncertainty in mixing models than existing approaches. We apply this procedure, referred to as G-EMMA, to a yearlong chemical data set from the heavily impacted agricultural Lissertocht catchment, Netherlands, and compare its results to the traditional end-member mixing analysis (EMMA). While the traditional approach appears unable to adequately deal with the large spatial variation in one of the end-members, the G-EMMA procedure successfully identified, with varying uncertainty, contributions of five different end-members to the stream. Our results suggest that the concentration distribution of effective end-members, that is, the flux-weighted input of an end-member to the stream, can differ markedly from that inferred from sampling of water stored in the catchment. Results also show that the uncertainty arising from identifying the correct end-members may alter calculated end-member contributions by up to 30%, stressing the importance of including the identification of end-members in the uncertainty assessment.
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| 9. |
- Ellerbæk Nielsen, J., et al.
(författare)
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GLUE based marine X-band weather radar data calibration and uncertainty estimation
- 2015
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Ingår i: Urban Water Journal. - 1573-062X. ; 12:4, s. 283-294
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Tidskriftsartikel (refereegranskat)abstract
- The Generalized Likelihood Uncertainty Estimation methodology (GLUE) is investigated for radar rainfall calibration and uncertainty assessment. The method is used to calibrate radar data collected by a Local Area Weather Radar (LAWR).In contrast to other LAWR data calibrations, the method combines calibration with uncertainty estimation. Instead of searching for a single set of calibration parameters, the method uses the observations to construct distributions of the calibration parameters. These parameter sets provide valuable knowledge of parameter sensitivity and the uncertainty.Two approaches are analyzed; the static calibration approach, where the LAWR is calibrated once for a long period and the dynamic approach, where the estimate is continuously adjusted based on ground observations.The analysis illustrates that the static calibration performs insufficiently, whereas the dynamic adjustment improves the performance significantly.It is found that even if the dynamic adjustment method is used the uncertainty of rainfall estimates can still be significant.
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| 10. |
- Gallart, F., et al.
(författare)
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Using internal catchment information to reduce the uncertainty of discharge and baseflow prediction
- 2007
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Ingår i: Advances in Water Resources. - : Elsevier BV. - 0309-1708 .- 1872-9657. ; 30:4, s. 808-823
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Tidskriftsartikel (refereegranskat)abstract
- The semi-distributed hydrological model TOPMODEL was tested with data from the Can Vila research basin (Vallcebre) in order to verify its adequacy for simulating runoff and the relative contributions from saturated overland flow and groundwater flow. After a test of the overall performance of the model, only data from a wet period were selected for this work. The test was performed using the GLUE method. The model was conditioned on continuous discharge and water table records. Furthermore, point measurements of recession flow simultaneous with water table depth and the extent of saturated areas were used to condition the distributions of the more relevant parameters, using new or updated evaluation measures. A wide range of parameter sets provided acceptable results for flow simulation when the model was conditioned on flow data alone, and the uncertainty of prediction of the contribution from groundwater was extremely large. However, conditioning on water table records and the distribution of parameters obtained from point observations strongly reduced the uncertainty of predictions for both stream flow and groundwater contribution.
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| 11. |
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| 12. |
- Leedal, D., et al.
(författare)
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Visualization approaches for communicating real-time flood forecasting level and inundation information
- 2010
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Ingår i: Journal of Flood Risk Management. - 1753-318X. ; 3:2, s. 140-150
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Tidskriftsartikel (refereegranskat)abstract
- The January 2005 flood event in the Eden catchment (UK) has focused considerable research effort towards strengthening and extending operational flood forecasting in the region. The Eden catchment has become a key study site within the remit of phase two of the Flood Risk Management Research Consortium. This paper presents a synthesis of results incorporating model uncertainty analysis, computationally efficient real-time data assimilation/forecasting algorithms, two-dimensional (2D) inundation modelling, and data visualization for decision support. The emphasis here is on methods of presenting information from a new generation of probabilistic flood forecasting models. Using Environment Agency rain and river-level gauge data, a data-based mechanistic model is identified and incorporated into a modified Kalman Filter (KF) data assimilation algorithm designed for real-time flood forecasting applications. The KF process generates forecasts within a probabilistic framework. A simulation of the 6-h ahead forecast for river levels at Sheepmount (Carlisle) covering the January 2005 flood event is presented together with methods of visualizing the associated uncertainty. These methods are then coupled to the 2D hydrodynamic LISFLOOD-FP model to produce real-time flood inundation maps. The value of incorporating probabilistic information is emphasized.
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| 13. |
- Page, T., et al.
(författare)
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Modelling the chloride signal at Plynlimon, Wales, using a modified dynamic TOPMODEL incorporating conservative chemical mixing (with uncertainty)
- 2007
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Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 21:3, s. 292-307
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Tidskriftsartikel (refereegranskat)abstract
- The application of a modified version of dynamic TOPMODEL for two subcatchments at Plynlimon, Wales is described. Conservative chemical mixing within mobile and immobile stores has been added to the hydrological model in an attempt to simulate observed stream chloride concentrations. The model was not fully able to simulate the observed behaviour, in particular the short- to medium-term dynamics. One of the primary problems highlighted by the study was the representation of dry deposition and cloud-droplet-deposited chloride, which formed a significant part of the long-term chloride mass budget. Equifinality of parameter sets inhibited the ability to determine the effective catchment mixing volumes and coefficients or the most likely partition between occult mass inputs and chloride mass inputs determined by catchment immobile-store antecedent conditions. Some success was achieved, in as much as some aspects of the dynamic behaviour of the signal were satisfactorily simulated, although spectral analysis showed that the model could not fully reproduce the 1/f power spectra of observed stream chloride concentrations with its implications of a wide distribution of residence times for water in the catchment.
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| 14. |
- Pappenberger, F., et al.
(författare)
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Uncertainty Analysis in Environmental Modeling Made Easy
- 2007
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Ingår i: EOS. - 0096-3941 .- 2324-9250. ; 88:3
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Tidskriftsartikel (refereegranskat)abstract
- Uncertainty analysis assesses the uncertainty in numerical model outputs that arises from ambiguity in model structures, parameters, boundary conditions, and evaluation data. An analysis of the impact of uncertainties should be undertaken in every environmental modeling exercise. Many techniques exist, however, and each requires an investment of time and resources to learn. The potential analyst is faced with the difficult question of which technique is best to use and which may be put off.
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| 15. |
- Piñol, J., et al.
(författare)
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Conditioning uncertainty in ecological models : Assessing the impact of fire management strategies
- 2007
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800 .- 1872-7026. ; 207:1, s. 34-44
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Tidskriftsartikel (refereegranskat)abstract
- A simple simulation model has been used to investigate whether large fires in Mediterranean regions are a result of extreme weather conditions or the cumulative effect of a policy of fire suppression over decades. The model reproduced the fire regime characteristics for a wide variety of regions of Mediterranean climate in California, France and Spain. The Generalised Likelihood Uncertainty Estimation (GLUE) methodology was used to assess the possibility of multiple model parameter sets being consistent with the available calibration data. The resulting set of behavioural models was used to assess uncertainty in the predictions. The results suggested that (1) for a given region, the total area burned is much the same whether suppression or prescribed fire policies are used or not; however fire suppression enhances fire intensity and prescribed burning reduces it; (2) the proportion of large fires can be reduced, but not eliminated, using prescribed fires, especially in areas which have the highest proportion of large fires.
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| 16. |
- Rinaldo, A., et al.
(författare)
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Catchment travel time distributions and water flow in soils
- 2011
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Ingår i: Water resources research. - 0043-1397 .- 1944-7973. ; 47, s. W07537-
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Tidskriftsartikel (refereegranskat)abstract
- Many details about the flow of water in soils in a hillslope are unknowable given current technologies. One way of learning about the bulk effects of water velocity distributions on hillslopes is through the use of tracers. However, this paper will demonstrate that the interpretation of tracer information needs to become more sophisticated. The paper reviews, and complements with mathematical arguments and specific examples, theory and practice of the distribution(s) of the times water particles injected through rainfall spend traveling through a catchment up to a control section (i.e., "catchment" travel times). The relevance of the work is perceived to lie in the importance of the characterization of travel time distributions as fundamental descriptors of catchment water storage, flow pathway heterogeneity, sources of water in a catchment, and the chemistry of water flows through the control section. The paper aims to correct some common misconceptions used in analyses of travel time distributions. In particular, it stresses the conceptual and practical differences between the travel time distribution conditional on a given injection time (needed for rainfall-runoff transformations) and that conditional on a given sampling time at the outlet (as provided by isotopic dating techniques or tracer measurements), jointly with the differences of both with the residence time distributions of water particles in storage within the catchment at any time. These differences are defined precisely here, either through the results of different models or theoretically by using an extension of a classic theorem of dynamic controls. Specifically, we address different model results to highlight the features of travel times seen from different assumptions, in this case, exact solutions to a lumped model and numerical solutions of the 3-D flow and transport equations in variably saturated, physically heterogeneous catchment domains. Our results stress the individual characters of the relevant distributions and their general nonstationarity yielding their legitimate interchange only in very particular conditions rarely achieved in the field. We also briefly discuss the impact of oversimple assumptions commonly used in analyses of tracer data.
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| 17. |
- Romanowicz, Renata J., et al.
(författare)
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A data based mechanistic approach to nonlinear flood routing and adaptive flood level forecasting
- 2008
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Ingår i: Advances in Water Resources. - : Elsevier BV. - 0309-1708 .- 1872-9657. ; 31:8, s. 1048-1056
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Tidskriftsartikel (refereegranskat)abstract
- Operational flood forecasting requires accurate forecasts with a suitable lead time, in order to be able to issue appropriate warnings and take appropriate emergency actions. Recent improvements in both flood plain characterization and computational capabilities have made the use of distributed flood inundation models more common. However, problems remain with the application of such models. There are still uncertainties associated with the identifiability of parameters, with the computational burden of calculating distributed estimates of predictive uncertainty, and with the adaptive use of such models for operational, real-time flood inundation forecasting. Moreover, the application of distributed models is complex, costly and requires high degrees of skill. This paper presents an alternative to distributed inundation models for real-time flood forecasting that provides fast and accurate, medium to short-term forecasts. The Data Based Mechanistic (DBM) methodology exploits a State Dependent Parameter (SDP) modelling approach to derive a nonlinear dependence between the water levels measured at gauging stations along the river. The transformation of water levels depends on the relative geometry of the channel cross-sections, without the need to apply rating curve transformations to the discharge. The relationship obtained is used to transform water levels as an input to a linear, on-line, real-time and adaptive stochastic DBM model. The approach provides an estimate of the prediction uncertainties, including allowing for heterescadasticity of the multi-step-ahead forecasting errors. The approach is illustrated using an 80 km reach of the River Severn, in the UK.
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| 18. |
- Romanowicz, R J, et al.
(författare)
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Data assimilation and adaptive forecasting of water levels in the river Severn catchment, United Kingdom
- 2006
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Ingår i: Water resources research. - 0043-1397 .- 1944-7973. ; 42:6, s. W06407-
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Tidskriftsartikel (refereegranskat)abstract
- [ 1] This paper describes data assimilation (DA) and adaptive forecasting techniques for flood forecasting and their application to forecasting water levels at various locations along a 120 km reach of the river Severn, United Kingdom. The methodology exploits the top-down, data-based mechanistic (DBM) approach to the modeling of environmental processes, concentrating on the identification and estimation of those "dominant modes'' of dynamic behavior that are most important for flood prediction. In particular, hydrological processes active in the catchment are modeled using the state-dependent parameter ( SDP) method of estimating a nonlinear, effective rainfall transformation together with a linear stochastic transfer function (STF) method for characterizing both the effective rainfall - river level behavior and the river level routing processes. The complete model consists of these lumped parameter, linear and nonlinear stochastic, dynamic elements connected in a quasi-distributed manner that represents the physical structure of the catchment. The adaptive forecasting system then utilizes a state-space form of the complete catchment model, including allowance for heteroscedasticity in the errors, as the basis for data assimilation and forecasting using a Kalman filter forecasting engine. Here the predicted model states ( water levels) and adaptive parameters are updated recursively in response to input data received in real time from sensors in the catchment. Direct water level forecasting is considered, rather than flow, because this removes the need to transform the level measurement through the rating curve and tends to decrease the forecasting errors.
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| 19. |
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| 20. |
- Smith, P. J., et al.
(författare)
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Detection of structural inadequacy in process-based hydrological models : A particle-filtering approach
- 2008
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Ingår i: Water resources research. - 0043-1397 .- 1944-7973. ; 44:1, s. W01410-
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, increasing computational power has been used to weight competing hydrological models in a Bayesian framework to improve predictive power. This may suggest that for a given measure of association with the observed data, one hydrological model is superior to another. However, careful analyses of the residuals of the model fit are required to propose further improvements to the model. In this paper we consider an alternative method of analyzing the shortcomings in a hydrological model. The hydrological model parameters are treated as varying in time. Simulation using a particle filter algorithm then reveals the parameter distribution needed at each time to reproduce the observed data. The resulting parameter, and the corresponding model state, distributions can be analyzed to propose improvements to the hydrological model. A demonstrative example is presented using rainfall-runoff data from the Leaf River, United States. This indicates that even when explicitly representing the uncertainty of the observed rainfall and discharge series, the technique shows shortcomings in the model structure.
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| 21. |
- Smith, P. J., et al.
(författare)
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Testing probabilistic adaptive real-time flood forecasting models
- 2014
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Ingår i: Journal of Flood Risk Management. - : Wiley. - 1753-318X. ; 7:3, s. 265-279
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Tidskriftsartikel (refereegranskat)abstract
- Operational flood forecasting has become a complex and multifaceted task, increasingly being treated in probabilistic ways to allow for the inherent uncertainties in the forecasting process. This paper reviews recent applications of data-based mechanistic (DBM) models within the operational UK National Flood Forecasting System. The position of DBM models in the forecasting chain is considered along with their offline calibration and validation. The online adaptive implementation with assimilation of water level information as used for forecasting is outlined. Two example applications based upon UK locations where severe flooding has occurred, the River Eden at Carlisle and River Severn at Shrewsbury, are presented.
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| 22. |
- Smith, Paul J, et al.
(författare)
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Towards the provision of site specific flood warnings using wireless sensor networks
- 2009
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Ingår i: Meteorological Applications. - : Wiley. - 1350-4827 .- 1469-8080. ; 16, s. 57-64
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Tidskriftsartikel (refereegranskat)abstract
- An important aspect of flood risk management is the issuing of timely flood alerts. The spatial, as well as temporal, scale of these warnings is important. In many situations efficient risk management may be aided by the provision of local flood predictions at a high spatial resolution. Examples of such situations include issuing warnings for small groups of outlying houses or key infrastructure locations Such as power sub-stations. In this paper a methodology for providing automated, detailed and location specific warnings which are computed ‘on-site’ is presented. Copyright (C) 2009 Royal Meteorological Society
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| 23. |
- Westerberg, Ida K., et al.
(författare)
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Regional water balance modelling using flow-duration curves with observational uncertainties
- 2014
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 18:8, s. 2993-3013
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Tidskriftsartikel (refereegranskat)abstract
- Robust and reliable water-resource mapping in ungauged basins requires estimation of the uncertainties in the hydrologic model, the regionalisation method, and the observational data. In this study we investigated the use of regionalised flow-duration curves (FDCs) for constraining model predictive uncertainty, while accounting for all these uncertainty sources. A water balance model was applied to 36 basins in Central America using regionally and globally available precipitation, climate and discharge data that were screened for inconsistencies. A rating-curve analysis for 35 Honduran discharge stations was used to estimate discharge uncertainty for the region, and the consistency of the model forcing and evaluation data was analysed using two different screening methods. FDCs with uncertainty bounds were calculated for each basin, accounting for both discharge uncertainty and, in many cases, uncertainty stemming from the use of short time series, potentially not representative for the modelling period. These uncertain FDCs were then used to regionalise a FDC for each basin, treating it as ungauged in a cross-evaluation, and this regionalised FDC was used to constrain the uncertainty in the model predictions for the basin. There was a clear relationship between the performance of the local model calibration and the degree of data set consistency - with many basins with inconsistent data lacking behavioural simulations (i.e. simulations within predefined limits around the observed FDC) and the basins with the highest data set consistency also having the highest simulation reliability. For the basins where the regionalisation of the FDCs worked best, the uncertainty bounds for the regionalised simulations were only slightly wider than those for a local model calibration. The predicted uncertainty was greater for basins where the result of the FDC regionalisation was more uncertain, but the regionalised simulations still had a high reliability compared to the locally calibrated simulations and often encompassed them. The regionalised FDCs were found to be useful on their own as a basic signature constraint; however, additional regionalised signatures could further constrain the uncertainty in the predictions and may increase the robustness to severe data inconsistencies, which are difficult to detect for ungauged basins.
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| 24. |
- Wilkinson, M. E., et al.
(författare)
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A cloud based tool for knowledge exchange on local scale flood risk
- 2015
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 161, s. 38-50
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Tidskriftsartikel (refereegranskat)abstract
- There is an emerging and urgent need for new approaches for the management of environmental challenges such as flood hazard in the broad context of sustainability. This requires a new way of working which bridges disciplines and organisations, and that breaks down science-culture boundaries. With this, there is growing recognition that the appropriate involvement of local communities in catchment management decisions can result in multiple benefits. However, new tools are required to connect organisations and communities. The growth of cloud based technologies offers a novel way to facilitate this process of exchange of information in environmental science and management; however, stakeholders need to be engaged with as part of the development process from the beginning rather than being presented with a final product at the end. Here we present the development of a pilot Local Environmental Virtual Observatory Flooding Tool. The aim was to develop a cloud based learning platform for stakeholders, bringing together fragmented data, models and visualisation tools that will enable these stakeholders to make scientifically informed environmental management decisions at the local scale. It has been developed by engaging with different stakeholder groups in three catchment case studies in the UK and a panel of national experts in relevant topic areas. However, these case study catchments are typical of many northern latitude catchments. The tool was designed to communicate flood risk in locally impacted communities whilst engaging with landowners/farmers about the risk of runoff from the farmed landscape. It has been developed iteratively to reflect the needs, interests and capabilities of a wide range of stakeholders. The pilot tool combines cloud based services, local catchment datasets, a hydrological model and bespoke visualisation tools to explore real time hydrometric data and the impact of flood risk caused by future land use changes. The novel aspects of the pilot tool are; the co-evolution of tools on a cloud based platform with stakeholders, policy and scientists; encouraging different science disciplines to work together; a wealth of information that is accessible and understandable to a range of stakeholders; and provides a framework for how to approach the development of such a cloud based tool in the future. Above all, stakeholders saw the tool and the potential of cloud technologies as an effective means to taking a whole systems approach to solving environmental issues. This sense of community ownership is essential in order to facilitate future appropriate and acceptable land use management decisions to be co-developed by local catchment communities. The development processes and the resulting pilot tool could be applied to local catchments globally to facilitate bottom up catchment management approaches.
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| 25. |
- Ameli, Ali A., et al.
(författare)
-
Primary weathering rates, water transit times, and concentration-discharge relations : A theoretical analysis for the critical zone
- 2017
-
Ingår i: Water resources research. - : AMER GEOPHYSICAL UNION. - 0043-1397 .- 1944-7973. ; 53:1, s. 942-960
-
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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| 26. |
- Beven, Keith, et al.
(författare)
-
Epistemic uncertainties and natural hazard risk assessment - Part 1 : A review of different natural hazard areas
- 2018
-
Ingår i: Natural hazards and earth system sciences. - : COPERNICUS GESELLSCHAFT MBH. - 1561-8633 .- 1684-9981. ; 18:10, s. 2741-2768
-
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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| 27. |
- Beven, Keith, et al.
(författare)
-
Epistemic uncertainties and natural hazard risk assessment - Part 2 : What should constitute good practice?
- 2018
-
Ingår i: Natural hazards and earth system sciences. - : COPERNICUS GESELLSCHAFT MBH. - 1561-8633 .- 1684-9981. ; 18:10, s. 2769-2783
-
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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| 28. |
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| 29. |
- Beven, Keith J., et al.
(författare)
-
Communicating uncertainty in flood inundation mapping : a case study
- 2015
-
Ingår i: International Journal of River Basin Management. - : Informa UK Limited. - 1571-5124 .- 1814-2060. ; 13:3, s. 285-295
-
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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| 30. |
- Beven, Keith J., et al.
(författare)
-
GLUE : 20 years on
- 2014
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 28:24, s. 5897-5918
-
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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| 31. |
- Beven, Keith J., et al.
(författare)
-
Hyperresolution information and hyperresolution ignorance in modelling the hydrology of the land surface
- 2015
-
Ingår i: SCIENCE CHINA-EARTH SCIENCES. - : Springer Science and Business Media LLC. - 1674-7313 .- 1869-1897. ; 58:1, s. 25-35
-
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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| 32. |
- Beven, Keith J., et al.
(författare)
-
Modelling everything everywhere : a new approach to decision-making for water management under uncertainty
- 2012
-
Ingår i: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 57, s. 124-132
-
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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| 33. |
- Beven, Keith J., et al.
(författare)
-
Rethinking Concepts of Information Content of Hydrological Data to Account for Epistemic Errors
- 2014
-
Ingår i: Vulnerability, Uncertainty, and Risk. - Reston, VA : American Society of Civil Engineers. - 9780784413609 ; , s. 263-272
-
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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| 34. |
- Beven, Keith J., et al.
(författare)
-
The uncertainty cascade in model fusion
- 2017
-
Ingår i: Geological Society Special Publication. - 0305-8719 .- 2041-4927. ; 408:1, s. 255-266
-
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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| 35. |
- Beven, Keith J.
(författare)
-
Uncertainty in Predictions of Floods and Hydraulic Transport
- 2007
-
Ingår i: Transport phenomena in hydraulics. - Warszawa : Institute of Geophysics. - 9788388765735 ; , s. 5-20
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This paper provides a review of work within the Generalised Likelihood Uncertainty Estimation (GLUE) methodology on estimating uncertainties in predicting flood frequency, flood inundation, and hydraulic transport of solutes in rivers and soils. The issue of prediction uncertainty as an input decision making is also discussed. It is concluded that in real applications it is unlikely that a fully objective approach to uncertainty estimation is possible. It is therefore important that the assumptions made are stated explicitly so that they can be agreed or disputed with the users of the resulting predictions. It is also important that the modelling process be considered as a learning process of constraining uncertainty by adding new information.
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| 36. |
- Beven, Keith, et al.
(författare)
-
On the colour and spin of epistemic error (and what we might do about it)
- 2011
-
Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 15:10, s. 3123-3133
-
Tidskriftsartikel (refereegranskat)abstract
- Disinformation as a result of epistemic error is an issue in hydrological modelling. In particular the way in which the colour in model residuals resulting from epistemic errors should be expected to be non-stationary means that it is difficult to justify the spin that the structure of residuals can be properly represented by statistical likelihood functions. To do so would be to greatly overestimate the information content in a set of calibration data and increase the possibility of both Type I and Type II errors. Some principles of trying to identify periods of disinformative data prior to evaluation of a model structure of interest, are discussed. An example demonstrates the effect on the estimated parameter values of a hydrological model.
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| 37. |
- Beven, Keith, et al.
(författare)
-
So just why would a modeller choose to be incoherent?
- 2008
-
Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 354:1-4, s. 15-32
-
Tidskriftsartikel (refereegranskat)abstract
- This article provides an extended response to the criticisms of the GLUE methodology by Mantovan and Todini [Mantovan, P., Todini, E., 2006. Hydrological forecasting uncertainty assessment: incoherence of the GLUE methodology. J. Hydrol. 330, 368-381]. 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. Under such assumptions, GLUE can be coherent in the sense of Manotvan and Todini. In real applications, however, with multiple sources of uncertainty including model structural error, their strong definition of coherence is shown to be inapplicable to the extent that the choice of a format likelihood function based on a simple error structure may be an incoherent choice. It is demonstrated by some relatively minor modifications of their hypothetical example that misspecification of the error model and the non-stationarities associated with the presence of input error and model structural error in the Bayes approach will then produce well-defined but incorrect parameter distributions. This empirical result is quite independent of GLUE, but the flexibility of the GLUE approach may then prove to be an advantage in providing more coherent and robust choices of model evaluation in these cases and, by analogy, in other non-ideal cases for real applications. At the current time it is difficult to make a reasoned choice between methods of uncertainty estimation for real applications because of a lack of understanding of the real information content of data in conditioning models.
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| 38. |
- Blazkova, S, et al.
(författare)
-
Uncertainty in flood estimation
- 2009
-
Ingår i: Structure and Infrastructure Engineering. - : Informa UK Limited. - 1573-2479 .- 1744-8980. ; 5:4, s. 325-332
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of this contribution is to form a clear picture of uncertainties we encounter in flood estimation, including both real-time flood forecasting and simulation for flood risk estimation. In simulation, we prefer the thesis of equifinality to obtain global optima. Many models producing acceptable simulations can be considered as multiple working hypotheses about the system process representations. Some of those hypotheses might later be confirmed or rejected, given additional data. In GLUE (Generalized Likelihood Uncertainty Estimation) the parameter sets are sampled randomly from physically reasonable ranges, often using uniform sampling where there is no strong information about prior expectations of parameter values. The parameter sets are then used to generate different realizations of the model outputs, which are then evaluated using some criteria (measures of likelihood) to provide a weight associated with each parameter set. Likelihood here is used in a much broader sense than in statistical inference. If some limits of effective observation error can be specified prior to running any simulations, models predicting outside of those limits can then be rejected as non-behavioural. Thus, any model evaluation of this type needs to take account of the multiple sources of model error more explicitly. This, however, is difficult for realistic cases. The procedure for the GLUE methodology is illustrated in examples. Usability for practical problems is suggested and future development is outlined.
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| 39. |
- Choi, H.T., et al.
(författare)
-
Multi-period and Multi-criteria Model Conditioning to Reduce Prediction Uncertainty in Distributed Rainfall-Runoff Modelling within GLUE framework
- 2007
-
Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 332:3-4, s. 316-336
-
Tidskriftsartikel (refereegranskat)abstract
- A new approach to multi-criteria model evaluation is presented. The approach is consistent with the equifinality thesis and is developed within the Generalised Likelihood Uncertainty Estimation (GLUE) framework. The predictions of Monte Carlo realisations of TOPMODEL parameter sets are evaluated using a number of performance measures calibrated for both global (annual) and seasonal (30 day) periods. The seasonal periods were clustered using a Fuzzy C-means algorithm, into 15 types representing different hydrological conditions. The model shows good performance on a classical efficiency measure at the global level, but no model realizations were found that were behavioural over all multi-period clusters and all performance measures, raising questions about what should be considered as an acceptable model performance. Prediction uncertainties can still be calculated by allowing that different clusters require different parameter sets. Variations in parameter distributions between clusters, as well as examination of where observed discharges depart from model prediction bounds, give some indication of model structure deficiencies.
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| 40. |
- Davies, Jessica, et al.
(författare)
-
A discrete particle representation of hillslope hydrology : hypothesis testing in reproducing a tracer experiment at Gardsjon, Sweden
- 2011
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 25:23, s. 3602-3612
-
Tidskriftsartikel (refereegranskat)abstract
- Despite the long history of the continuum equation approach in hydrology, it is not a necessary approach to the formulation of a physically based representation of hillslope hydrology. The Multiple Interacting Pathways ( MIPs) model is a discrete realization that allows hillslope response and transport to be simultaneously explored in a way that reflects the potential occurrence of preferential flows and lengths of pathways. The MIPs model uses random particle tracking methods to represent the flow of water within the subsurface alongside velocity distributions that acknowledge preferential flows and transition probability matrices, which control flow pathways. An initial realization of this model is presented here in application to a tracer experiment carried out in Gardsjon, Sweden. The model is used as an exploratory tool, testing several hypotheses in relation to this experiment.
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| 41. |
- Davies, J., et al.
(författare)
-
Integrated modeling of flow and residence times at the catchment scale with multiple interacting pathways
- 2013
-
Ingår i: Water resources research. - : American Geophysical Union (AGU). - 0043-1397 .- 1944-7973. ; 49:8, s. 4738-4750
-
Tidskriftsartikel (refereegranskat)abstract
- There is still a need for catchment hydrological and transport models that properly integrate the effects of preferential flows while accounting for differences in velocities and celerities. A modeling methodology is presented here which uses particle tracking methods to simulate both flow and transport in multiple pathways in a single consistent solution. Water fluxes and storages are determined by the volume and density of particles and transport is attained by labeling the particles with information that may be tracked throughout the lifetime of that particle in the catchment. The methodology allows representation of preferential flows through the use of particle velocity distributions, and mixing between pathways can be achieved with pathway transition probabilities. A transferable 3-D modeling methodology is presented for the first time and applied to a unique step-shift isotope experiment that was carried out at the 0.63 ha G1 catchment in Gardsjon, Sweden. This application highlights the importance of combining flow and transport in hydrological representations, and the importance of pathway velocity distributions and interactions in obtaining a satisfactory representation of the observations.
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| 42. |
- Dean, Sarah, et al.
(författare)
-
Uncertainty assessment of a process-based integrated catchment model of phosphorus
- 2009
-
Ingår i: Stochastic environmental research and risk assessment (Print). - : Springer Science and Business Media LLC. - 1436-3240 .- 1436-3259. ; 23, s. 991-1010
-
Tidskriftsartikel (refereegranskat)abstract
- Despite the many models developed for phosphorus concentration prediction at differing spatial and temporal scales, there has been little effort to quantify uncertainty in their predictions. Model prediction uncertainty quantification is desirable, for informed decision-making in river-systems management. An uncertainty analysis of the process-based model, integrated catchment model of phosphorus (INCA-P), within the generalised likelihood uncertainty estimation (GLUE) framework is presented. The framework is applied to the Lugg catchment (1,077 km(2)), a River Wye tributary, on the England-Wales border. Daily discharge and monthly phosphorus (total reactive and total), for a limited number of reaches, are used to initially assess uncertainty and sensitivity of 44 model parameters, identified as being most important for discharge and phosphorus predictions. This study demonstrates that parameter homogeneity assumptions (spatial heterogeneity is treated as land use type fractional areas) can achieve higher model fits, than a previous expertly calibrated parameter set. The model is capable of reproducing the hydrology, but a threshold Nash-Sutcliffe co-efficient of determination (E or R (2)) of 0.3 is not achieved when simulating observed total phosphorus (TP) data in the upland reaches or total reactive phosphorus (TRP) in any reach. Despite this, the model reproduces the general dynamics of TP and TRP, in point source dominated lower reaches. This paper discusses why this application of INCA-P fails to find any parameter sets, which simultaneously describe all observed data acceptably. The discussion focuses on uncertainty of readily available input data, and whether such process-based models should be used when there isn’t sufficient data to support the many parameters.
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| 43. |
- Di Baldassarre, Giuliano, et al.
(författare)
-
Flood-plain mapping : a critical discussion of deterministic and probabilistic approaches
- 2010
-
Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 55:3, s. 364-376
-
Tidskriftsartikel (refereegranskat)abstract
- Different methodologies for flood-plain mapping are analysed and discussed by comparing deterministic and probabilistic approaches using hydrodynamic numerical solutions. In order to facilitate the critical discussion, state-of-art techniques in the field of flood inundation modelling are applied to a specific test site (River Dee, UK). Specifically, different flood-plain maps are derived for this test site. A first map is built by applying an advanced deterministic approach: use of a fully two-dimensional finite element model (TELEMAC-2D), calibrated against a historical flood extent, to derive a 1-in-100 year flood inundation map. A second map is derived by using a probabilistic approach: use of a simple raster-based inundation model (LISFLOOD-FP) to derive an uncertain flood extent map predicting the 1-in-100 year event conditioned on the extent of the 2006 flood. The flood-plain maps are then compared and the advantages and disadvantages of the two different approaches are critically discussed.
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| 44. |
- Faulkner, H., et al.
(författare)
-
Developing a translational discourse to communicate uncertainty in flood risk between science and the practitioner
- 2007
-
Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 36:8, s. 692-704
-
Tidskriftsartikel (refereegranskat)abstract
- The language and tools of risk and uncertainty estimation in flood risk management (FRM) are rarely optimized for the extant communication challenge. This paper develops the rationale for a pragmatic semiotics of risk communication between scientists developing flood models and forecasts and those professional groups who are the receptors for flood risk estimates and warnings in the UK. The current barriers to effective communication and the constraints involved in the formation of a communication language are explored, focusing on the role of the professional's agenda or “mission” in creating or reducing those constraints. The tools available for the development of this discourse, for both flood warnings in real time and generalized FRM communications, are outlined. It is argued that the contested ownership of the articulation of uncertainties embedded in flood risk communications could be reduced by the development of a formally structured translational discourse between science and professionals in FRM, through which process “codes of practice” for uncertainty estimation in different application areas can be developed. Ways in which this might take place in an institutional context are considered.
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| 45. |
- Gallart, Francesc, et al.
(författare)
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Upscaling discrete internal observations for obtaining catchment-averaged TOPMODEL parameters in a small Mediterranean mountain basin
- 2008
-
Ingår i: Physics and Chemistry of the Earth. - : Elsevier BV. - 1474-7065 .- 1873-5193. ; 33:17-18, s. 1090-1094
-
Tidskriftsartikel (refereegranskat)abstract
- Discrete observations on recession flows, local depth to the water table and the extent of saturated areas were used in the Vallcebre small research basin for obtaining the distribution functions of the TOPMODEL catchment parameters that drive the behaviour of the saturated store. Using this parameter information within GLUE framework, the robustness of discharge simulations was improved and the uncertainty of flow separation between two components was significantly reduced when compared with the results obtained with customary calibration with flow data at the outlet. Nevertheless, the analysis of the uncertainty in the determination of the local value of the topographic index at the piezometer location demonstrated that this may be a relevant limitation of the approach, particularly for high values of the topographic index, and a careful selection of the piezometer is recommended. The use of the extent of saturated areas provided the best and more representative results, although the simulated patterns of saturated areas did not match well the observed ones, because the role of local controls beyond the topographic index.
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| 46. |
- Iorgulescu, I., et al.
(författare)
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Flow, mixing, and displacement in using a data-based hydrochemical model to predict conservative tracer data
- 2007
-
Ingår i: Water resources research. - 0043-1397 .- 1944-7973. ; 43:3, s. W03401-
-
Tidskriftsartikel (refereegranskat)abstract
- We extend the data-based hydrochemical model of Iorgulescu et al. (2005), able to simulate discharge and reactive chemical tracer concentrations (silica and calcium) in streamflow for subcatchments of the Haute-Mentue research basin (Switzerland), to the prediction of additional δ 18O values treated as a conservative tracer. The hydrochemical model is based on a parameterization of three runoff components (direct precipitation (DP), acid soil water (AS), and deep groundwater (GW)) in a chemical mixing model. Each component is modeled through an identical structure consisting of a nonlinear gain and a linear transfer function with two reservoirs (fast/slow) in parallel having a constant partition between them. We formulate a set of hypotheses concerning the isotope characterization of each component to provide additional information about how new rainfall inputs are processed in the hydrological response of the catchment. In particular, the AS component is modeled through a nested structure of hypotheses (models) of increasing complexity. It will be shown that hydrological processes in the hillslope associated with the DP, AS, and GW components are especially effective in filtering of higher-frequency fluctuations in precipitation isotopic ratios at the intraevent, interevent/seasonal, and annual/multiannual timescales. The highly nonlinear and nonstationary AS component represents predominantly “recent” water stored in the upper decimeters of the soil profile. Results also suggest that subsurface pathways are significant for the DP component. A local flow path mechanism is proposed for explaining the large fluxes of subsurface flows.
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| 47. |
- Kretzschmar, A., et al.
(författare)
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Reversing hydrology : quantifying the temporal aggregation effect of catchment rainfall estimation using sub-hourly data
- 2016
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Ingår i: HYDROLOGY RESEARCH. - : IWA Publishing. - 1998-9563 .- 0029-1277 .- 2224-7955. ; 47:3, s. 630-645
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Tidskriftsartikel (refereegranskat)abstract
- Inferred rainfall sequences generated by a novel method of inverting a continuous time transfer function show a smoothed profile when compared to the observed rainfall, however, streamflow generated using the inferred catchment rainfall is almost identical to observed streamflow (R-t(2) > 97%). This paper compares the effective rainfall inferred by the regularised inversion process (termed inferred effective rainfall (IER)) proposed by the authors with effective rainfall derived from the observed catchment rainfall (termed observed effective rainfall (OER)) in both time and frequency domains in order to confirm that, by using the dominant catchment dynamics in the inversion process, the main characteristics of catchment rainfall are being captured by the IER estimates. Estimates of the resolution of the IER are found in the time domain by comparison with aggregated sequences of OER, and in the frequency domain by comparing the amplitude spectra of observed and IER. The temporal resolution of the rainfall estimates is affected by the slow time constant of the catchment, reflecting the presence of slow hydrological pathways, for example, aquifers, and by the rainfall regime, for example, dominance of convective or frontal rainfall. It is also affected by the goodness-of-fit of the original forward rainfall-streamflow model.
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| 48. |
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| 49. |
- Montanari, A., et al.
(författare)
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"Panta Rhei-Everything Flows" : Change in hydrology and society-The IAHS Scientific Decade 2013-2022
- 2013
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Ingår i: Hydrological Sciences Journal. - : Taylor & Francis Group. - 0262-6667 .- 2150-3435. ; 58:6, s. 1256-1275
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Tidskriftsartikel (refereegranskat)abstract
- The new Scientific Decade 2013-2022 of IAHS, entitled Panta RheiEverything Flows, is dedicated to research activities on change in hydrology and society. The purpose of Panta Rhei is to reach an improved interpretation of the processes governing the water cycle by focusing on their changing dynamics in connection with rapidly changing human systems. The practical aim is to improve our capability to make predictions of water resources dynamics to support sustainable societal development in a changing environment. The concept implies a focus on hydrological systems as a changing interface between environment and society, whose dynamics are essential to determine water security, human safety and development, and to set priorities for environmental management. The Scientific Decade 2013-2022 will devise innovative theoretical blueprints for the representation of processes including change and will focus on advanced monitoring and data analysis techniques. Interdisciplinarity will be sought by increased efforts to connect with the socio-economic sciences and geosciences in general. This paper presents a summary of the Science Plan of Panta Rhei, its targets, research questions and expected outcomes.
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| 50. |
- Pappenberger, F., et al.
(författare)
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Fuzzy set approach to calibrating distributed flood inundation models using remote sensing observations
- 2007
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 11:2, s. 739-752
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents a methodology for the estimation of uncertainty of inundation extent, which takes account of the uncertainty in the observed spatially distributed information and implements a fuzzy evaluation methodology. The Generalised Likelihood Uncertainty Estimation (GLUE) technique and the 2-D LISFLOOD-FP model were applied to derive the set of uncertain inundation realisations and resulting flood inundation maps. Conditioning of the inundation maps on fuzzified Synthetic Aperture Radar (SAR) images results in much more realistic inundation risk maps which can better depict the variable pattern of inundation extent than previously used methods. It has been shown that the evaluation methodology compares well to traditional approaches and can produce flood hazard maps that reflect the uncertainties in model evaluation.
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