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2006

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Modelling Farmer Decision Making For Natural Resource Management Outcomes, Brett A. Bryan, J. Ward, Neville D. Crossman Jul 2006

Modelling Farmer Decision Making For Natural Resource Management Outcomes, Brett A. Bryan, J. Ward, Neville D. Crossman

International Congress on Environmental Modelling and Software

This paper presents a conceptual modelling and simulation methodology that incorporates dryland farmer decision making into regional- and landscape-level natural resource management (NRM) planning. Decision making for many NRM on ground actions is made at the farm level so it makes sense to incorporate farmer behaviour into regional planning for meeting regional environmental objectives. Our model applies multi-attribute farmer utility functions within an agent-based simulation environment to model temporal change in land use and landscapes resulting from farmer implementation of on ground NRM actions. Farmer decision profiles are characterized using a survey of over 500 farmers. Landscape futures can also …

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Environmental Policy Aid Under Uncertainty, J. Myšiak, J. D. Brown Jul 2006

Environmental Policy Aid Under Uncertainty, J. Myšiak, J. D. Brown

International Congress on Environmental Modelling and Software

Uncertainty pervades all aspects of environmental policy making. Numerous typologies and techniques have been developed to conceptualise, classify, assess (qualitatively and quantitatively), propagate, control, reduce and communicate uncertainty. Such assessments are a necessary but insufficient condition for reducing uncertainty in environmental decision making. In this paper we discuss how uncertainty is translated into decisions. Since this entails numerous value judgements and trade-offs which are sensitive to how policy problems are framed, we argue that perceptions of uncertainty cannot be viewed independently of the (quality of) the policy process that it intends to inform. Thus, uncertainty management should not be limited …

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Application Of Mesocasimir: Assessment Of Baetis Rhodani Habitat Suitability, A. M. Mouton, M. Schneider, I. Kopecki, Peter L. M. Goethals, N. De Pauw Jul 2006

Application Of Mesocasimir: Assessment Of Baetis Rhodani Habitat Suitability, A. M. Mouton, M. Schneider, I. Kopecki, Peter L. M. Goethals, N. De Pauw

International Congress on Environmental Modelling and Software

The assessment of the ecological status of running waters at a mesohabitat scale is commonly based on fish. Nevertheless, due to their strong dependence on a good physical and chemical habitat, macroinvertebrate species can also be used for this assessment. A new approach is presented by applying the MesoCASiMiR module of the CASiMiR modeling system. In this way, the habitat suitability for the mayfly Baetis rhodani was modeled at a mesohabitat scale in the river Zwalm (Flanders, Belgium). The model inference system was based on fuzzy logic. Fuzzy variable sets and rules were derived from expert knowledge and from a …

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Landscape Modeling And Spatial Optimization Of Management Practices To Restore Water Quality In The St. Albans Bay Watershed, Vermont, Erica Gaddis, Alexey Voinov Jul 2006

Landscape Modeling And Spatial Optimization Of Management Practices To Restore Water Quality In The St. Albans Bay Watershed, Vermont, Erica Gaddis, Alexey Voinov

International Congress on Environmental Modelling and Software

Diffuse (non-point source) pollution from urban stormwater and agricultural runoff are among the leading causes of water pollution in the United States. Currently, most management plans that address diffuse pollution are driven by dissociated economic, political and ecological interests that are difficult to reconcile. Integrated watershed management aims to protect and improve water resources while considering economic and social concerns in the community. Participatory environmental management requires tools, such as landscape models, that can be used to visualize and evaluate the possible outcomes of various management strategies. The overall objective of this project is to develop and implement a framework …

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Air Quality Modelling: State-Of-The-Art, R. San José, A. Baklanov, R. S. Sokhi, Kostas Karatzas, J. L. Pérez Jul 2006

Air Quality Modelling: State-Of-The-Art, R. San José, A. Baklanov, R. S. Sokhi, Kostas Karatzas, J. L. Pérez

International Congress on Environmental Modelling and Software

Air quality modeling is an area with a significant progress and interest during the last two decades. It covers all aspects related to pollution dispersion and impact on different ecosystems. It is very much related to the meteorological field since the atmosphere is governed by the general laws derived by the Navier-Stokes equation system. Progress in computer capabilities during the last decades has impulse substantially the research on air quality modeling in a parallel way. Air pollution modeling covers a very complex and interdisciplinary area where we include remote sensing – land use impact -, initial and boundary conditions, data …

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State-Parameter Estimation Of Ecosystem Models Using A Smoothed Ensemble Kalman Filter, M. Chen, Shuguang Liu, Larry L. Tieszen Jul 2006

State-Parameter Estimation Of Ecosystem Models Using A Smoothed Ensemble Kalman Filter, M. Chen, Shuguang Liu, Larry L. Tieszen

International Congress on Environmental Modelling and Software

Much of the effort in data assimilation methods for carbon dynamics analysis has focused on estimating optimal values for either model parameters or state variables. The main weakness of estimating parameter values alone (i.e., without considering state variables) is that all errors from input, output, and model structure are attributed to model parameter uncertainties. On the other hand, the accuracy of estimating state variables may be reduced if the temporal evolution of parameter values is not incorporated. This research develops a smoothed ensemble Kalman filter (SEnKF) to estimate simultaneously the system states and model parameters of an eddy flux partition …

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Quasi-2d Approach In Modelling The Transport Of Contaminated Sediments In Floodplains During River Flooding - Model Coupling And Uncertainty Analysis, K. -E Lindenschmidt, J. Rauberg Jul 2006

Quasi-2d Approach In Modelling The Transport Of Contaminated Sediments In Floodplains During River Flooding - Model Coupling And Uncertainty Analysis, K. -E Lindenschmidt, J. Rauberg

International Congress on Environmental Modelling and Software

In flood modelling, many one-dimensional (1D) hydrodynamic and water-quality models are too restricted in capturing the spatial differentiation of processes within the floodplain and two-dimensional (2D) models are too demanding in data requirements and computational resources. The latter is an important consideration when uncertainty analyses using the Monte Carlo technique are to complement the modelling exercises. Hence, we have developed a quasi-2D modelling approach which still calculates the dynamic wave in 1D but the discretisation of the computational units is in 2D, allowing a better spatial representation of the flow and substance transport processes in the floodplain without a large …

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A Framework For Assessing Uncertainty In Ecosystem Models, M. Wattenbach, Pia Gottschalk, Fred Hattermann, Claus Rachimow, Michael Flechsig, Pete Smith Jul 2006

A Framework For Assessing Uncertainty In Ecosystem Models, M. Wattenbach, Pia Gottschalk, Fred Hattermann, Claus Rachimow, Michael Flechsig, Pete Smith

International Congress on Environmental Modelling and Software

In addition to their use as research tools, ecosystem models have been used more frequently in the last two decades to support policy decisions and inform stakeholder consultations. Models have been central to the work of the Intergovernmental Panel of Climate Change (IPCC) and the International Geosphere-Biosphere Programme (IGBP). The usefulness of results from model simulations for any purpose is determined by their quality like the uncertainty accompanying model outputs. In model evaluation, however, a broad variety of different approaches to define uncertainty still exists and these have not, so far, been standardized. In contrast, field research has already defined …

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An Optimal Control And Options Theory Approach To Forecasting And Managing Sustainable Systems, Y. Shastri, U. Diwekar Jul 2006

An Optimal Control And Options Theory Approach To Forecasting And Managing Sustainable Systems, Y. Shastri, U. Diwekar

International Congress on Environmental Modelling and Software

Sustainable management of the natural systems is essential in the presence of anthropogenic andnatural disasters. Fisher information based measure and hypothesis have been proposed to quantify the sustainabilityof natural systems, which are used in this work to formulate management objectives. Since uncertaintyis omnipresent in natural systems, its consideration is important. Real options theory deals extensively with therepresentation and forecasting of uncertainty. The options theory, with the Ito mean reverting process, is usedto represent uncertainty, and optimal control theory is used to derive time dependent decisions. The idea isimplemented on a three species predator-prey model. The results highlight the effect of …

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A 3d Hydrodynamic Lake Model: Simulation On Great Slave Lake, Luis F. León, David C. L. Lam, William Schertzer, David Swayne Jul 2006

A 3d Hydrodynamic Lake Model: Simulation On Great Slave Lake, Luis F. León, David C. L. Lam, William Schertzer, David Swayne

International Congress on Environmental Modelling and Software

Large lakes are recognized as an important influence on the circulation of the atmosphere; in return the resulting meteorological forcing also affects the lake thermal structure. This interaction is complex and continues to be a critical issue considering the millions of lakes in Canada, many of which are large, and are unaccounted for in the current climatic models. This paper evaluates the predictive capability of the 3-D Estuary and Lake COmputer Model (ELCOM) using relatively high quality data collected on Great Slave Lake - one of the largest lakes of the world in Canada’s northern climatic system. This assessment is …

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Challenges Encountered During Integrated Modelling Across Multiple Catchments, Neville D. Crossman, Brett A. Bryan Jul 2006

Challenges Encountered During Integrated Modelling Across Multiple Catchments, Neville D. Crossman, Brett A. Bryan

International Congress on Environmental Modelling and Software

There has been a recent trend in natural resource management decision making toward target setting and the use of models to identify geographic priorities to meet those targets. However, measurable and quantitative targets for assessing progress toward achieving management and policy goals tend not to be established. This may be due in large part to a lack of clarity in data and model availability, and geographic prioritisation processes. The long history of extensive human activity and modification of natural resources in the Murray Darling Basin of southern Australia has led to a myriad of natural resource management problems, particularly dryland …

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Environmental Policy Aid Under Uncertainty, J. Myšiak, J. D. Brown Jul 2006

Environmental Policy Aid Under Uncertainty, J. Myšiak, J. D. Brown

International Congress on Environmental Modelling and Software

Uncertainty pervades all aspects of environmental policy making. Numerous typologies and techniques have been developed to conceptualise, classify, assess (qualitatively and quantitatively), propagate, control, reduce and communicate uncertainty. Such assessments are a necessary but insufficient condition for reducing uncertainty in environmental decision making. In this paper we discuss how uncertainty is translated into decisions. Since this entails numerous value judgements and trade-offs which are sensitive to how policy problems are framed, we argue that perceptions of uncertainty cannot be viewed independently of the (quality of) the policy process that it intends to inform. Thus, uncertainty management should not be limited …

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Application Of Mesocasimir: Assessment Of Baetis Rhodani Habitat Suitability, A. M. Mouton, M. Schneider, I. Kopecki, Peter L. M. Goethals, N. De Pauw Jul 2006

Application Of Mesocasimir: Assessment Of Baetis Rhodani Habitat Suitability, A. M. Mouton, M. Schneider, I. Kopecki, Peter L. M. Goethals, N. De Pauw

International Congress on Environmental Modelling and Software

The assessment of the ecological status of running waters at a mesohabitat scale is commonly based on fish. Nevertheless, due to their strong dependence on a good physical and chemical habitat, macroinvertebrate species can also be used for this assessment. A new approach is presented by applying the MesoCASiMiR module of the CASiMiR modeling system. In this way, the habitat suitability for the mayfly Baetis rhodani was modeled at a mesohabitat scale in the river Zwalm (Flanders, Belgium). The model inference system was based on fuzzy logic. Fuzzy variable sets and rules were derived from expert knowledge and from a …

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Lake Erie Hypoxia Simulations With Elcom-Caedym, Luis F. León, Ralph E. H. Smith, Jose R. Romero, Robert E. Hecky Jul 2006

Lake Erie Hypoxia Simulations With Elcom-Caedym, Luis F. León, Ralph E. H. Smith, Jose R. Romero, Robert E. Hecky

International Congress on Environmental Modelling and Software

This paper presents the simulation of the dissolved oxygen (DO) dynamics in the central basin of Lake Erie using a three-dimensional hydrodynamic model (ELCOM) coupled with an aquatic ecological model (CAEDYM). The objective was to simulate the recurrent hypoxic conditions that occur in the shallow hypolimnion of the central basin of the lake after the onset of stratification. In early spring, oxygen concentrations are relatively high, but by late summer, large areas in the central basin of Lake Erie are effectively hypoxic (andlt;2 mg l-1). This numerical modeling study successfully reproduced horizontal variability and vertical decay of dissolved oxygen during …

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Numerical Simulation Of Flow And Tracer Transport In A Disinfection Contact Tank, C. Gualtieri Jul 2006

Numerical Simulation Of Flow And Tracer Transport In A Disinfection Contact Tank, C. Gualtieri

International Congress on Environmental Modelling and Software

Chlorine is extensively used to disinfect drinking water supply. However, the design of chlorine contact tank is usually based on the volume displacement criterion, paying attention that detention time would be at least of half an hour. This criterion relies upon the assumption that plug-flow conditions hold along the tank. However, the existence and arrangement of baffles in the tank, and the tank inlet and outlet configurations can result in a much more complex flow pattern, where turbulent mixing, dead-zones and short-circuiting exist. This situation could result in an inefficient use of chlorine due to the formation of potentially carcinogenic …

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Tools To Support A Model-Based Methodology For Benefit/Cost/Risk Analysis Of Wastewater Treatment Systems, Lorenzo Benedetti, Davide Bixio, Filip Claeys, Peter A. Vanrolleghem Jul 2006

Tools To Support A Model-Based Methodology For Benefit/Cost/Risk Analysis Of Wastewater Treatment Systems, Lorenzo Benedetti, Davide Bixio, Filip Claeys, Peter A. Vanrolleghem

International Congress on Environmental Modelling and Software

This paper presents a set of tools developed to support an innovative four-step methodology to design and upgrade wastewater treatment systems. For the first step of data collection and data reconstruction, two different tools have been developed, one for situations where data are available (using data reconstruction methods) and another for situations where no data are (yet) available (based on a simple draining catchment model driven by actual local rain series). The second step, i.e. model building, implied the development of a new simulation platform and of grid software to deal with the considerable simulation load generated by the third …

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Quasi-2d Approach In Modelling The Transport Of Contaminated Sediments In Floodplains During River Flooding - Model Coupling And Uncertainty Analysis, K. -E Lindenschmidt, J. Rauberg Jul 2006

Quasi-2d Approach In Modelling The Transport Of Contaminated Sediments In Floodplains During River Flooding - Model Coupling And Uncertainty Analysis, K. -E Lindenschmidt, J. Rauberg

International Congress on Environmental Modelling and Software

In flood modelling, many one-dimensional (1D) hydrodynamic and water-quality models are too restricted in capturing the spatial differentiation of processes within the floodplain and two-dimensional (2D) models are too demanding in data requirements and computational resources. The latter is an important consideration when uncertainty analyses using the Monte Carlo technique are to complement the modelling exercises. Hence, we have developed a quasi-2D modelling approach which still calculates the dynamic wave in 1D but the discretisation of the computational units is in 2D, allowing a better spatial representation of the flow and substance transport processes in the floodplain without a large …

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Two-Dimensional Hydraulic Modeling Approach To Linking Stream Morphology And Aquatic Habitat Quality, J. S. Clark, W. C. Hession, Donna M. Rizzo, J. P. Laible, M. C. Watzin Jul 2006

Two-Dimensional Hydraulic Modeling Approach To Linking Stream Morphology And Aquatic Habitat Quality, J. S. Clark, W. C. Hession, Donna M. Rizzo, J. P. Laible, M. C. Watzin

International Congress on Environmental Modelling and Software

A two-dimensional hydrodynamic model (River2D) was utilized to evaluate the relationship between geomorphic condition (as estimated using an existing rapid assessment protocol) and instream habitat quality in small Vermont streams. Six stream reaches ranging in geomorphic condition from good to poor according to the protocols were utilized for this study. We conducted detailed topographic surveys, quantified bed substrate, and measured velocity values during baseflow conditions. The reach models were calibrated with realistic roughness values based on field observations and pebble counts. After calibration, the flows were scaled up to median and bankfull flows for additional analysis. The weighted usable area …

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Landscape Design And Agricultural Land-Use Allocation Using Pareto-Based Multi-Objective Differential Evolution, Jeroen C. J. Groot, Walter A. H. Rossing, André Jellema, Martin Van Ittersum Jul 2006

Landscape Design And Agricultural Land-Use Allocation Using Pareto-Based Multi-Objective Differential Evolution, Jeroen C. J. Groot, Walter A. H. Rossing, André Jellema, Martin Van Ittersum

International Congress on Environmental Modelling and Software

Intensively managed agricultural areas in North-Western Europe are undergoing a shift from solely production oriented use to provision of multiple services and functions. Design of multifunctional agricultural landscapes can be supported by exploration of the potential to effectively combine economic performance, landscape identity, nature conservation and environmental quality. The Landscape IMAGES methodology enables spatially explicit exploration of options by multi-objective optimization, for multifunctional agriculture in landscapes at a scale of a few km². The framework has been developed to support stakeholder discussions and informed decision making. For simultaneous optimization of multiple objectives the evolutionary algorithm of Differential Evolution is employed. …

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Ecohydraulics In The Mississippi River: Freshwater Mussel Dynamics Model, J. A. Daraio, Y. Morales-Chaves, Arthur E. Mynett, L. Weber Jul 2006

Ecohydraulics In The Mississippi River: Freshwater Mussel Dynamics Model, J. A. Daraio, Y. Morales-Chaves, Arthur E. Mynett, L. Weber

International Congress on Environmental Modelling and Software

The family Unionidae (freshwater mussels) is geographically diverse with species found worldwide; their greatest diversity is found in North America. Zebra mussels (Dreissena polymorpha) are an exotic species introduced into North America in the 1980’s that has since become a threat to economic interests and native mussel species in the region. IIHR-Hydroscience and Engineering and WL|Delft Hydraulics are developing a numerical model of mussel population dynamics for the purpose of analyzing alternative management strategies of zebra mussels and Unionidae in the Upper Mississippi River (UMR). The Mussel Dynamics Model (MDM) simulates interaction of mussels and the hydraulic environment. This paper …

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Landscape Modeling And Spatial Optimization Of Management Practices To Restore Water Quality In The St. Albans Bay Watershed, Vermont, Erica Gaddis, Alexey Voinov Jul 2006

Landscape Modeling And Spatial Optimization Of Management Practices To Restore Water Quality In The St. Albans Bay Watershed, Vermont, Erica Gaddis, Alexey Voinov

International Congress on Environmental Modelling and Software

Diffuse (non-point source) pollution from urban stormwater and agricultural runoff are among the leading causes of water pollution in the United States. Currently, most management plans that address diffuse pollution are driven by dissociated economic, political and ecological interests that are difficult to reconcile. Integrated watershed management aims to protect and improve water resources while considering economic and social concerns in the community. Participatory environmental management requires tools, such as landscape models, that can be used to visualize and evaluate the possible outcomes of various management strategies. The overall objective of this project is to develop and implement a framework …

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Multiobjective Optimization Procedure For Control Strategies In Environmental Systems, Xavier Flores, Joaquim Comas, Ignasi Rodríguez-Roda, Laureano Jiménez, Rene Bañares-Alcántara Jul 2006

Multiobjective Optimization Procedure For Control Strategies In Environmental Systems, Xavier Flores, Joaquim Comas, Ignasi Rodríguez-Roda, Laureano Jiménez, Rene Bañares-Alcántara

International Congress on Environmental Modelling and Software

This paper presents a systematic procedure for multiobjective optimization of control strategies in environmental systems. The optimization of control strategies in environmental systems is a complex activity due to the large number of objectives that must be considered simultaneously e.g. economic, environmental, technical, legal. The accomplishment of those objectives generates significant synergies, but in many cases they are subject of clear trade-offs. This procedure is approached as a multicriteria decision analysis (MCDA) and involves the quantification and normalization of a set of evaluation criteria and a weighted sum. A sensitivity analysis is also included in order to show the variation …

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Data Mining Approaches To Explaining Aerosol Formation, Saara Hyvonen, Heikki Junninen, Lauri Laakso, Miikka Dal Maso, Tiia Gronholm, Boris Bonn, Petri Keronen, Pasi Aalto, Veijo Hiltunen, Toivo Pohja, Samuli Launiainen, Pertti Hari, Heikki Mannila, H.C. Hansoon, M. Kulmala Jul 2006

Data Mining Approaches To Explaining Aerosol Formation, Saara Hyvonen, Heikki Junninen, Lauri Laakso, Miikka Dal Maso, Tiia Gronholm, Boris Bonn, Petri Keronen, Pasi Aalto, Veijo Hiltunen, Toivo Pohja, Samuli Launiainen, Pertti Hari, Heikki Mannila, H.C. Hansoon, M. Kulmala

International Congress on Environmental Modelling and Software

Atmospheric aerosol particle formation is frequently observed in various environments. Yet, despite numerous studies, processes behind these so called nucleation events remain unclear. In this work we describe the use of data mining techniques to detect factors influencing particle formation. These techniques are applied to a dataset of eight years of 80 variables collected at the boreal forest station (SMEAR II) in Southern Finland, including air pollutant, weather, gas and particle measurements. In a previous study classification methods have been used together with feature selection in order to understand what causes nucleation. Each day was classified as an event day, …

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Intelligent Configuration Of Numerical Solvers Of Environmental Ode/Dae Models Using Machine Learning Techniques, Petra Claeys, Peter A. Vanrolleghem Jul 2006

Intelligent Configuration Of Numerical Solvers Of Environmental Ode/Dae Models Using Machine Learning Techniques, Petra Claeys, Peter A. Vanrolleghem

International Congress on Environmental Modelling and Software

The models considered in this work contain combinations of a large number of non-linear differential equations and algebraic equations, which have to be solved numerically. Because of this, running simulation experiments on a computer can be very time-consuming, i.e. it can last for days or even weeks. On top of that, some solvers are not appropriate for solving certain of these systems. For example, stiff solvers are only appropriate for stiff systems while they are not the best choice for non-stiff systems. Choosing the appropriate solver and solver settings for a certain initialized model can significantly shorten the computation time. …

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Finding Relevant Features For The Characterization Of The Ecological Status Of Human Altered Streams Using A Constrained Mixture Model, Alfredo Vellido, Joaquim Comas, Raul Cruz, Eugenia Marte Jul 2006

Finding Relevant Features For The Characterization Of The Ecological Status Of Human Altered Streams Using A Constrained Mixture Model, Alfredo Vellido, Joaquim Comas, Raul Cruz, Eugenia Marte

International Congress on Environmental Modelling and Software

The large dimensionality of real data sets usually hampers the interpretability of the results of their analysis. In a previous study, some stream data that are part of the knowledge base of an environmental decision support system were explored through clustering and visualization. The interpretability of these clustering results would be improved by the use of a feature selection strategy based on a method capable of ranking the observed features according to their relative relevance. In this paper, we use one such a method that is an integral part of a probabilistic model for multivariate data clustering and visualization: Generative …

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A Framework For Assessing Uncertainty In Ecosystem Models, M. Wattenbach, Pia Gottschalk, Fred Hattermann, Claus Rachimow, Michael Flechsig, Pete Smith Jul 2006

A Framework For Assessing Uncertainty In Ecosystem Models, M. Wattenbach, Pia Gottschalk, Fred Hattermann, Claus Rachimow, Michael Flechsig, Pete Smith

International Congress on Environmental Modelling and Software

In addition to their use as research tools, ecosystem models have been used more frequently in the last two decades to support policy decisions and inform stakeholder consultations. Models have been central to the work of the Intergovernmental Panel of Climate Change (IPCC) and the International Geosphere-Biosphere Programme (IGBP). The usefulness of results from model simulations for any purpose is determined by their quality like the uncertainty accompanying model outputs. In model evaluation, however, a broad variety of different approaches to define uncertainty still exists and these have not, so far, been standardized. In contrast, field research has already defined …

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Experiences On Empirical Assessment Of Rule-Based Ai Systems For Ecological Modelling, V. Brilhante Jul 2006

Experiences On Empirical Assessment Of Rule-Based Ai Systems For Ecological Modelling, V. Brilhante

International Congress on Environmental Modelling and Software

In working with Artificial Intelligence (AI) techniques,more specifically logic-based knowledgerepresentation and reasoning, applied to environmentalmodelling, again more specifically, to automatingaspects of construction of ecological simulationmodels of the system dynamics kind, I havehad a couple of opportunities to work on projectswhere comparative empirical assessments of systemswere performed. More and more, the degree ofcomplexity of AI systems renders them unsuitablefor purely theoretical analytical studies, compellingus to resort to empirical methods which throughdata can flesh out the workings of a system and helpus understand its behaviour and results.

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Systematic Simplification Of Mechanistic Models, Neil Crout, Glen Cox, James Gibbons Jul 2006

Systematic Simplification Of Mechanistic Models, Neil Crout, Glen Cox, James Gibbons

International Congress on Environmental Modelling and Software

Models of environmental systems are often complex, reflecting the complexity of the systems they try and describe. This complexity is difficult to manage and, especially in the face of limited observed data, there is a risk that models become over-parameterised with the result that predictions are less reliable than they need be. An approach to investigating the influence of model complexity on prediction accuracy is to compare the performance of alternative (simpler) model formulations. However this is difficult to achieve in practice as the process of simplification can be time-consuming with the consequence that only a few alternative formulations can …

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Rank-Equivalence Method For Sensitivity Analysis Of An Integrated Model Of A River Catchment, J. K. Ravalico, Graeme C. Dandy, Holger R. Maier Jul 2006

Rank-Equivalence Method For Sensitivity Analysis Of An Integrated Model Of A River Catchment, J. K. Ravalico, Graeme C. Dandy, Holger R. Maier

International Congress on Environmental Modelling and Software

Integrated Assessment Modelling (IAM) incorporates knowledge from different disciplines to provide an overarching assessment of the impact of different management decisions. Integrated models generally require numerous parameters from varying sources, many not known with certainty. Rapid increases in model size and complexity, particularly in the case of integrated models for decision-making, pose new challenges for effective sensitivity analysis. Some of the identified shortcomings of existing sensitivity analysis methods in the context of IAM include: computational inefficiency, failure to assess parameter interactions, excessive data requirements (e.g. requiring parameter probability distributions), assumptions of model linearity and monotonicity and, in particular, difficulty of …

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Modelling Of Water Pollution In Urban Areas With Gis And Multivariate Statistical Methods, L. Matejicek Jul 2006

Modelling Of Water Pollution In Urban Areas With Gis And Multivariate Statistical Methods, L. Matejicek

International Congress on Environmental Modelling and Software

Integrating modelling of water pollution and GIS enables the connection of environmental process models with geospatial data describing the physical environment. Time series of water pollution data at monitoring profiles are used to complement the spatial database and to interpret the results of data analysis. In this case, the multivariate statistical methods provide an exploratory environment for data analysis and an indication of seasonal changes in the framework of surface water pollution. In addition to a wide range of useful multivariate methods, principal component analysis (PCA) and factor analysis (FA) are used to differentiate seasonal water pollution at monitoring profiles. …

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