Search results for "certainty"
showing 10 items of 1057 documents
Bayesian approach for uncertainty quantification in water quality modelling: The influence of prior distribution
2010
Summary Mathematical models are of common use in urban drainage, and they are increasingly being applied to support decisions about design and alternative management strategies. In this context, uncertainty analysis is of undoubted necessity in urban drainage modelling. However, despite the crucial role played by uncertainty quantification, several methodological aspects need to be clarified and deserve further investigation, especially in water quality modelling. One of them is related to the “a priori” hypotheses involved in the uncertainty analysis. Such hypotheses are usually condensed in “a priori” distributions assessing the most likely values for model parameters. This paper explores…
Uncertainty in sewer sediment deposit modelling: detailed vs simplified modelling approaches.
2012
Abstract The paper presents the results of a study in which the uncertainty levels associated with a detailed and a simplified/parsimonious sewer sediment modelling approach have been compared. The detailed approach used an Infoworks CS sewer network model combined with a user developed sediment transport code and the simplified approach used a conceptual sewer flow and quality model. The two approaches have been applied to a single case study sewer network and the simulation results compared. The case study was selected as moderate storm events had occurred during a 2 year rainfall and sewer flow monitoring period. Flooding had been observed and this was thought to be caused by significant…
Role of Modeling Uncertainty in the Estimation of Climate and Socioeconomic Impact on River Water Quality
2012
AbstractClimate is one of the most important factors leading to changes in the hydrologic and environmental characteristics of river basins. When considering water quality, the natural factors should be weighed against anthropogenic factors (such as urbanization, increased population, and higher water demand) that may increase or decrease the effect of climatic modifications. Any prediction of future climatic and anthropogenic scenarios is affected by uncertainty and the modelling tools that are used for evaluating their impact on receiving water bodies. The present paper is aimed at investigating the complexity of such analyses and the uncertainty related to future impact predictions based…
Uncertainty assessment of sewer sediment erosion modelling
2008
Urban stormwater quality modelling has become a fundamental issue in the evaluation of the receiving water bodies' quality state. Laboratory study as well as field campaigns have widely demonstrated that combined sewer sediments present cohesive-like properties which increase their resistance to erosion. However, only few models take sewer sediments into account considering their rheological properties. In the present paper different sewer sediment erosion models have been tested and their uncertainties have been assessed. The main goal was to discriminate the algorithms with respect to their robustness and the reduction of uncertainty. In order to accomplish such objective the GLUE methodo…
Uncertainty analysis of the influence of rainfall time resolution in the modelling of urban drainage systems
2005
In urban drainage modelling, rainfall temporal variability can be considered as one of the most critical knowledge elements when dealing with rainfall–runoff models input data. The rainfall data temporal resolution usually available for practical applications is often lower than that requested for the rainfall–runoff simulation in urban areas, greatly compromising model accuracy. The present paper evaluates the influence of rainfall temporal resolution on the uncertainty of the response of rainfall–runoff modelling in urban environments. Analyses have been carried out using historical rainfall–discharge data collected for about 10 years in Parco d'Orleans experimental catchment (Palermo, It…
Uncertainty assessment of an integrated urban drainage model
2009
Over the last few years, the use of mathematical models has gained importance in urban drainage system management; indeed, such models enable the combined analysis of different components that constitute a drainage system; the sewer system, wastewater treatment plant and the receiving water body. The effectiveness of an integrated approach has been widely demonstrated in the past and is presented in the EU Water Framework Directive, which also introduces a new point of view regarding the water quality management of the whole system, requiring a global analysis at the river basin scale for pollutant sources. However, integrated urban drainage models introduce several uncertain factors that a…
Assessment of the integrated urban water quality model complexity through identifiability analysis
2010
Urban sources of water pollution have often been cited as the primary cause of poor water quality in receiving water bodies (RWB), and recently many studies have been conducted to investigate both continuous sources, such as wastewater-treatment plant (WWTP) effluents, and intermittent sources, such as combined sewer overflows (CSOs). An urban drainage system must be considered jointly, i.e., by means of an integrated approach. However, although the benefits of an integrated approach have been widely demonstrated, several aspects have prevented its wide application, such as the scarcity of field data for not only the input and output variables but also parameters that govern intermediate st…
A new index for measuring seasonality: A transportation cost approach
2017
Abstract Seasonal fluctuations characterize many natural and social phenomena. Although the causes and impacts of seasonality are generally well documented in different study contexts, and many methods for isolating the seasonal component have been developed, considerably less attention has been paid to the measurement of the degree of seasonality. After reviewing the main indices used for measuring seasonality in different study contexts, we will propose a new approach in which seasonality is evaluated on the basis of the solution of a transportation problem. By considering the interdisciplinary nature of seasonal phenomena, the topic of measuring seasonality merits attention from a wide v…
Global sensitivity analysis for urban water quality modelling: comparison of different methods
2012
Sensitivity analysis represents an important step in improving the understanding and use of environmental models. Indeed, by means of global sensitivity analysis (GSA), modellers may identify both important (factor prioritization) and non-influential (factor fixing) model input factors. However, despite the potentialities of GSA methods, only few applications have been published in the field of urban drainage modelling. In order to fill this gap this paper presents a comparison among three GSA methods (SRC, Extended-FAST and Morris screening) on an urban drainage storm-water model. In particular, an exhaustive discussion on their peculiarities, applicability, and reliability is presented. S…
Risky choices in strategic environments: An experimental investigation of a real options game
2019
Managers frequently make decisions under conditions of fundamental uncertainty due the stochastic nature of the outcomes and competitive rivalry. In this study, we experimentally test a theoretical model under fundamental uncertainty and competitive rivalry by designing a sequential interaction game between two players. The first mover can decide either to choose a sure outcome that assigns a risky outcome to the second mover or to pass the decision to the second mover. If the second player gets the chance to decide, she can choose between a sure outcome, conditioned by the assignment of a risky payoff to the first mover, or the sharing of the risky outcome with the first mover. We then int…