Understanding predictive uncertainty in hydrologic modeling: The challenge of identifying input and structural errors

Meaningful quantification of data and structural uncertainties in conceptual rainfall-runoff modeling is a major scientific and engineering challenge. This paper focuses on the total predictive uncertainty and its decomposition into input and structural components under different inference scenarios. Several Bayesian inference schemes are investigated, differing in the treatment of rainfall and structural uncertainties, and in the precision of the priors describing rainfall uncertainty. Compared with traditional lumped additive error approaches, the quantification of the total predictive uncertainty in the runoff is improved when rainfall and/or structural errors are characterized explicitly. However, the decomposition of the total uncertainty into individual sources is more challenging. In particular, poor identifiability may arise when the inference scheme represents rainfall and structural errors using separate probabilistic models. The inference becomes ill‐posed unless sufficiently precise prior knowledge of data uncertainty is supplied; this ill‐posedness can often be detected from the behavior of the Monte Carlo sampling algorithm. Moreover, the priors on the data quality must also be sufficiently accurate if the inference is to be reliable and support meaningful uncertainty decomposition. Our findings highlight the inherent limitations of inferring inaccurate hydrologic models using rainfall‐runoff data with large unknown errors. Bayesian total error analysis can overcome these problems using independent prior information. The need for deriving independent descriptions of the uncertainties in the input and output data is clearly demonstrated.Benjamin Renard, Dmitri Kavetski, George Kuczera, Mark Thyer, and Stewart W. Frank

Ensemble evaluation of hydrological model hypotheses

It is demonstrated for the first time how model parameter, structural and data uncertainties can be accounted for explicitly and simultaneously within the Generalized Likelihood Uncertainty Estimation (GLUE) methodology. As an example application, 72 variants of a single soil moisture accounting store are tested as simplified hypotheses of runoff generation at six experimental grassland field-scale lysimeters through model rejection and a novel diagnostic scheme. The fields, designed as replicates, exhibit different hydrological behaviors which yield different model performances. For fields with low initial discharge levels at the beginning of events, the conceptual stores considered reach their limit of applicability. Conversely, one of the fields yielding more discharge than the others, but having larger data gaps, allows for greater flexibility in the choice of model structures. As a model learning exercise, the study points to a “leaking” of the fields not evident from previous field experiments. It is discussed how understanding observational uncertainties and incorporating these into model diagnostics can help appreciate the scale of model structural error

Realismo, naturalismo e semântica moral

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas, Programa de Pós-Graduação em Filosofia, Florianópolis, 2017.O naturalismo moral é a teoria metaética que sustenta que fatos e propriedades morais são fatos e propriedades naturais. Desde que G. E. Moore apresentou o seu argumento da questão aberta, tem havido várias críticas a essa teoria, o que fez com que os filósofos articulassem várias teorias metaéticas alternativas ao naturalismo, tais como intuicionismo, emotivismo, prescritivismo e a teoria do erro. Mas a partir da década de oitenta David Brink, Richard Boyd e Nicholas Sturgeon desenvolveram uma nova versão do naturalismo moral ? o naturalismo não reducionista ? que, argumentativamente, evita essas objeções e apresenta inúmeras outras vantagens. O resultado foi uma reascensão do realismo moral naturalista. No entanto, dois filósofos formularam uma objeção ao naturalismo não reducionista, que ficou conhecida como ?Argumento da Terra Gêmea Moral?, que tem gerado bastante discussão. O objetivo deste trabalho é reconstruir as linhas principais desse debate mostrando que: o naturalismo não reducionista realmente tem boas respostas a algumas críticas frequentes, tais como o argumento da questão aberta de Moore, a reformulação de Hare deste argumento, à objeção construtivista, à crítica de relativismo, ao argumento do desacordo moral etc; e que, mesmo que o argumento da terra gêmea moral seja o seu principal problema, o que parece ser o caso, há algumas estratégias de respostas possíveis a favor do naturalista.Abstract : Moral naturalism is the metaethical theory that maintains that moral facts and properties are natural facts and properties. Since G. E. Moore presented his open question argument there have been several critiques to this theory, which made the philosophers articulate several alternative metaethical theories to naturalism as intuitionism, emotivism, prescriptivism and the error theory. But from the eighties David Brink, Richard Boyd and Nicholas Sturgeon developed a new version of moral naturalism ? the non reductionist naturalism ? that, arguably, avoids these objections and it have numerous another advantages. The result was a resurrection of naturalistic moral realism. However, two philosophers formulated an objection to non reductionist naturalism that became known as ?Moral Twin Earth Argument? that has generated much discussion. The objective of this work is to reconstruct the main lines of this debate showing that: the non reductionist naturalism really have good replies to some frequent critiques such as Moore?s open question argument, Hare?s reformulation of this argument, the constructivist?s objection, the critique of relativism, to the moral disagreement?s argument etc; and that, even if the moral twin earth argument be its main problem, what looks to be the case, there are some possible response strategies in favor of the naturalist

The Field View: An Initial Examination of an Exploratory Eyewitness Identification Procedure

The field view is an identification procedure that was recently acknowledged in a national report assessing eyewitness identifications. However, the field view has not been empirically examined to date. In fact, very little is known regarding the effectiveness of the procedure. Because it is an exploratory procedure - used by police when they do not have a suspect in mind - it is important to determine how the field view fares in comparison to the traditional procedures such as lineups and showups, whereby police do have a suspect. Using a controlled, lab-based methodology, Study 1 examined correct and false identifications elicited from the field view procedure and whether filler similarity affects identification accuracy. Results revealed that the exploratory field view can be a harmful procedure, particularly when the perpetrator is not present in the location, as it produced significantly more false identifications (36%) than both the lineup (13%) and showup (5%) procedures. The reason for this alarmingly high rate of mistaken identifications is that in an exploratory procedure, there is not an a priori suspect, and thus, nobody in the location is known to be innocent, as fillers are in a lineup. Because of this, anyone identified would come under suspicion. A second study further examined whether the field view may be an acceptable identification procedure under a different circumstance, namely, when police do have a suspect. Study 2 used a more ecologically valid methodology to examine the hypothesis that this confirmatory field view procedure may fare superior to the showup under the condition that the field view is administered by someone who is blind to the identity of the suspect. Contrary to our predictions, however, all three procedures (i.e., field view with non-blind administration; field view with blind administration; showup) produced comparable correct and false identification rates. Overall, results indicate that a field view may be a viable procedure when it is used as a confirmatory procedure and includes fillers similar to the suspect. More research is needed to determine under what conditions exploratory procedures may be acceptable

A limited memory acceleration strategy for MCMC sampling in hierarchical Bayesian calibration of hydrological models

Hydrological calibration and prediction using conceptual models is affected by forcing/response data uncertainty and structural model error. The Bayesian Total Error Analysis methodology uses a hierarchical representation of individual sources of uncertainty. However, it is shown that standard multiblock “Metropolis-within-Gibbs” Markov chain Monte Carlo (MCMC) samplers commonly used in Bayesian hierarchical inference are exceedingly computationally expensive when applied to hydrologic models, which use recursive numerical solutions of coupled nonlinear differential equations to describe the evolution of catchment states such as soil and groundwater storages. This note develops a “limited-memory” algorithm for accelerating multiblock MCMC sampling from the posterior distributions of such models using low-dimensional jump distributions. The new algorithm exploits the decaying memory of hydrological systems to provide accurate tolerance-based approximations of traditional “full-memory” MCMC methods and is orders of magnitude more efficient than the latter.George Kuczera, Dmitri Kavetski, Benjamin Renard and Mark Thye

Eugenia e simetria de relações ou da impossibilidade da necessária independência moral a partir da permissibilidade da eugenia

The aim of this paper is to present what, for Habermas, is one of the implications of permissibility of eugenics, namely, breaking the symmetry relations. To do this, at first, we will introduce how the act of eugenics is a unilateral decision that does not take into account even hypothetically future interests of the fetus, even though it already participates indirectly of moral discourse. Secondly, we show the importance of symmetry in human relations, especially regarding the choice of the moral rules of the community of speakers. Thirdly, in possession of the importance of symmetry to the moral relations in speech communities, we show how the symmetry is broken when it comes to eugenics, condemning be manipulated to an irreversible dependence within of the discourse and making forever asymmetric relationship between who produces and what is produced.O objetivo deste texto é apresentar aquilo que, para Habermas, é uma das implicações da permissibilidade da eugenia, a saber, a quebra na simetria de relações. Para fazermos isso, num primeiro momento, apresentaremos como o ato da eugenia é uma decisão unilateral que não leva em conta nem mesmo hipoteticamente os futuros interesses do feto, ainda que este já participe de forma indireta do discurso moral. Num segundo momento, mostraremos a importância da simetria nas relações humanas, principalmente no que tange à escolha das regras morais da comunidade de falantes. Num terceiro momento, de posse da importância da simetria para as relações morais em comunidades de fala, mostraremos como a simetria é quebrada em se tratando de eugenia, condenando o ser manipulado a uma dependência irreversível no âmbito do discurso e tornando para sempre assimétrica a relação entre aquele que produz e aquilo que é produzido

Identification of Dominant Hydrological Mechanisms Using Bayesian Inference, Multiple Statistical Hypothesis Testing, and Flexible Models

ABSTARCT: In hydrological modeling, the identification of model mechanisms best suited for representing individual hydrological (physical) processes is of major scientific and operational interest. We present a statistical hypothesis-testing perspective on this model identification challenge and contribute a mechanism identification framework that combines: (i) Bayesian estimation of posterior probabilities of individual mechanisms from a given ensemble of model structures; (ii) a test statistic that defines a ?dominant? mechanism as a mechanism more probable than all its alternatives given observed data; and (iii) a flexible modeling framework to generate model structures using combinations of available mechanisms. The uncertainty in the test statistic is approximated using bootstrap sampling from the model ensemble. Synthetic experiments (with varying error magnitude and multiple replicates) and real data experiments are conducted using the hydrological modeling system FUSE (7 processes and 2?4 mechanisms per process yielding 624 feasible model structures) and data from the Leizarán catchment in northern Spain. The mechanism identification method is reliable: it identifies the correct mechanism as dominant in all synthetic trials where an identification is made. As data/model errors increase, statistical power (identifiability) decreases, manifesting as trials where no mechanism is identified as dominant. The real data case study results are broadly consistent with the synthetic analysis, with dominant mechanisms identified for 4 of 7 processes. Insights on which processes are most/least identifiable are also reported. The mechanism identification method is expected to contribute to broader community efforts on improving model identification and process representation in hydrology.The authors from IHCantabria acknowledge the financial support from the Government of Cantabria through the FÉNIX Program (ID 2020.03.03.322B.742.09)

Reply to comment by K. Beven et al. on "Pursuing the method of multiple working hypotheses for hydrological modelling"

Martyn P. Clark, Dmitri Kavetski, and Fabrizio Fenici