Search results for "Modelling"

Uncertainty in urban flood damage assessment due to urban drainage modeling and depth – damage curve estimation

2009

Propagation of precipitation measurement biases into the hydraulic modelling of urban drainage systems: a case study

2021

Precipitation is the primary source of freshwater, while it can have great socio-economical impacts associated with extreme weather events such as floods and droughts. Good quality hydro-meteorological data is an essential condition not only for climate analysis but also for warning systems, hydraulic structures design, risk assessment, etc. In fact, precipitation is one of the most intensively used variables in hydrological modelling and its measurement accuracy is of foremost importance (Peterson et al., 1998). Accurate and timely knowledge of precipitation characteristics at urban and natural basins scales is essential for understanding how different catchment hydrological systems operat…

Uncertainty estimation of a complex water quality model: GLUE vs Bayesian approach applied with Box – Cox transformation

2010

In urban drainage modelling, uncertainty analysis is of undoubted necessity; however, several methodological aspects need to be clarified and deserve to be investigated in the future, especially in water quality modelling. The use of the Bayesian approach to uncertainty analysis has been stimulated by its rigorous theoretical framework and by the possibility of evaluating the impact of new knowledge on the modelling estimates. Nevertheless, the Bayesian approach relies on some restrictive hypotheses that are not present in less formal methods like GLUE. One crucial point in the application of Bayesian methods is the formulation of a likelihood function that is conditioned by the hypotheses …

Global sensitivity analysis for micropollutant modeling by means of an urban integrated approach

2015

The paper presents the sensitivity analysis of an integrated urban water quality system by means of the global sensitivity analysis (GSA). Specifically, an home-made integrated model developed in previous studies has been modified in order to include the micropollutant assessment (namely, sulfamethoxazole - SMX). The model is able to estimate also the interactions between the three components of the system: sewer system (SS), wastewater treatment plant (WWTP) and the receiving water body (RWB). The analysis has been applied to an experimental catchment nearby Palermo (Italy): the Nocella catchment. Five scenarios each characterized by different combinations of sub-systems (i.e., SS, WWTP an…

Uncertainty propagation throughout an integrated water-quality model

2010

In integrated urban drainage water quality models, due to the fact that integrated approaches are basically a cascade of sub-models (simulating sewer system, wastewater treatment plant and receiving water body), uncertainty produced in one sub-model propagates to the following ones depending on the model structure, the estimation of parameters and the availability and uncertainty of measurements in the different parts of the system. Uncertainty basically propagates throughout a chain of models in which simulation output from upstream models is transferred to the downstream ones as input. The overall uncertainty can differ from the simple sum of uncertainties generated in each sub-model, dep…

Greenhouse gas emissions from integrated urban drainage systems: where do we stand?

2017

Integrated urban drainage systems (IUDS) (i.e., sewer systems, wastewater treatment plants and receiving water bodies) contribute to climate change being sources of greenhouse gas emissions (GHG). This paper, produced by the International Working Group on Data and Models, which works under the IWA/IAHR Joint Committee on Urban Drainage, reviews the state-of-the-art and the recently developed modelling tools used to understand and manage GHG emissions from IUDS. Further, open problems and research gaps are discussed, while proposing a framework for handling GHG from IUDS. The literature review reveals that there is a need to strengthen and partially adequate already available mathematical mo…

Variance-based sensitivity analysis for wastewater treatment plant modelling

2014

Global sensitivity analysis (GSA) is a valuable tool to support the use of mathematical models that characterise technical or natural systems. In the field of wastewater modelling, most of the recent applications of GSA use either regression-based methods, which require close to linear relationships between the model outputs and model factors, or screening methods, which only yield qualitative results. However, due to the characteristics of membrane bioreactors (MBR) (non-linear kinetics, complexity, etc.) there is an interest to adequately quantify the effects of non-linearity and interactions. This can be achieved with variance-based sensitivity analysis methods. In this paper, the Extend…

Global sensitivity analysis in ASM applications: comparison of the SRC and Extended-FAST method for a UCT-MBR model

2011

In this study global sensitivity analysis is performed to identify influential as well as non-influential parameters in a model of a University Cape Town Membrane Bioreactor (UCT-MBR). In particular, the Standardised Regression Coefficients (SRC) and Extended-FAST sensitivity analysis methods are applied. The sensitivity of model variables towards parameter variation is analysed for CODTOT, SNH4, SNO3, SPO, and MLSS along five reactor compartments. Both methods indicate that the parameters identified as being influential differ from section to section due to the different processes involved. Moreover, the relevant influence of the membrane filtration parameters is detected in the first plan…

Advanced course: innovative wastewater treatment and mathematical modelling

2015

During the last years many advances have matured in wastewater treatment both in terms of processes and mathematical modelling approaches. For a new generation of new scientists and engineers entering/working in the wastewater treatment field, the quantity, complexity and diversity of these new developments can be overwhelming. This Advanced Course on Innovative wastewater treatment processes and mathematical modelling will provide a comprehensive overview and a discussion platform for recent advances and trends currently under development in the context of wastewater treatment. This course is aimed at professionals (Master, PhD or equivalent experience) in wastewater treatment and mathemat…

Sensitivity and uncertainty analysis of a plant-wide model for carbon and energy footprint of wastewater treatment plants

2014

This paper presents the sensitivity and uncertainty analysis of a mathematical model for Greenhouse gas (GHG) and energy consumption assessment from wastewater treatment plants (WWTPs). The model is able to simultaneously describe the main biological and physical-chemical processes in a WWTP. Specifically, the mathematical model includes the main processes of the water and sludge lines influencing the methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) emissions. Further, the process energy demand and the energy recovery are also taken into account. The main objective of this paper is to analyze the key factors and sources of uncertainty influencing GHG emissions from WWTP at a pla…