Design of an Air-Quality Surveillance System for Buenos Aires City Integrated by a NO x Monitoring Network and Atmospheric Dispersion Models

This paper presents an air-quality surveillance system designed to detect the occurrence of air pollutant concentrations greater than a reference level in an urban area. The system is integrated by an air-quality monitoring network and atmospheric dispersion models simulations. An objective methodology to design an urban air-quality monitoring network is proposed. This methodology is based on the analysis of air-quality modelling results. The procedure is applied to design an air-quality monitoring network to control NO _x concentration levels in Buenos Aires City. Results indicate that six monitors will detect the occurrence of concentration greater than the air-quality guidelines with an efficiency of about 67%. Once a violation is detected, results of atmospheric dispersion models will help in the determination of affected areas. Four possible examples are included to illustrate the assistance that the results of atmospheric dispersion models can bring to a better estimation of possible affected areas in the city. Combining these results with the last census data, an estimation of the inhabitants possibly exposed is obtained.     

An Experimental Methodology for Monitoring Contaminant Transport Through Geotechnical Centrifuge Models

In this paper, an attempt has been made to highlight an experimental methodology for monitoring contaminant transport through locally available silty soil and commercially available clay in geotechnical centrifuge models, for different compaction states. Use of multiple depth sensors to determine depth distribution of sodium chloride in the soil column has been detailed. The obtained results have been compared with argentometric method. To validate the centrifuge modelling, modelling of models has been used. The test setup developed can simulate contaminant transport mechanisms through the soil mass, which is approximately 10 m deep, over a period of 600 days. R _e and P _e are found to be N times higher in the centrifuge models. These numbers are found to be several orders less than unity. This indicates that laminar flow prevails and the dominating Cl⁻ transport mechanism in centrifuge is diffusion. The study also highlights the fact that the geotechnical centrifuge modelling can be used as a viable alternative to field scale experimentation.     

Impact of model parameterization on predictive uncertainty of regional groundwater models in the context of environmental impact assessment

Parameterization strategy impacts models' outputs and the associated uncertainty. This is particularly true for transient regional groundwater models where parameters can only be weakly constrained by insufficient observations. However, this is rarely investigated under any particular model structure. This study bridges this gap using a regional groundwater model developed to understand the impact of coal seam gas extraction on groundwater systems in a probabilistic framework. Two different parameterization schemes were implemented for hydraulic conductivity and specific storage. The first method solely relies on the relationship between hydraulic properties and burial depths. The second more complex strategy allows more spatial variations of hydraulic parameters using pilot points. The study provides new insights and practical guidance on the application of groundwater modelling for environmental impact assessment. The results suggest that the choice of model parameterization has a significant influence on predictive uncertainty. The model using the simple parameterization provides predictions with a much wider range than the model with a more sophisticated parameterization. This is because that the lowly parameterized model tends to generate more extreme effective hydraulic parameter fields unless the parameterization simplification converts the inverse problem to a (close to) well-posed problem that rarely exists for applied regional groundwater modelling. The potential impact of model parameterization should be discussed explicitly in groundwater modelling applications to support decision making to avoid misinterpretation of the modelling results.     

Multi-level modelling of chlorination by-product presence in drinking water distribution systems for human exposure assessment purposes

During drinking water treatment and distribution, chlorine reacts with organic matter occurring in water to form various chlorination by-products (CBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). This paper presents the occurrence of THMs and HAAs in different water distribution systems (DS) of the same region and their modelling for exposure assessment purposes. This study was conducted in eight DS supplying chlorinated water to the population of Québec City, Canada. These systems differ in type of water source (i.e. surface, ground or mixed water), in treatment applied at the plant, and in size and structure of the DS. Two spatio-temporal databases for THMs and HAAs were implemented, one for model development and the other for model validation. The analysis of the data demonstrates significant seasonal and spatial variations of these compounds. A multi-level statistical modelling approach was applied to estimate the ranges for occurrence of THMs and HAAs in the eight DS (i.e. a single model for the study region for each CBP species). The modelling approach integrates available or easily measurable parameters. For both THMs and HAAs, a two-level model considering a sampling-site random effect was selected among various models initially developed. The model capacity for estimating the presence of THMs and HAAs in drinking water and its usefulness for exposure assessment purposes in the studied region was demonstrated.     

Assessment of a General Finite Line Source Model and CALINE4 for Vehicular Pollution Prediction in Ireland

A comparative evaluation of two Gaussian-based line source models namely, California line source dispersion model version 4 and the general finite line source model, is presented. The concentrations predicted by these models are compared with background-corrected ambient concentrations measured at three different distances from a motorway and performance of both models assessed in the context of integrated transport–environment modelling for regulatory purposes.     

OSPM - A Parameterised Street Pollution Model

For many practical applications, as e.g. in support of air pollution management, numerical models based on solution of the basic flow and dispersion equations are still too complex. Alternative are models that are basically parameterised semi-empirical models making use of a priori assumptions about the flow and dispersion conditions. However, these models must, be thoroughly tested and their performance and limitations carefully documented. The Danish Operational Street Pollution Model (OSPM) belongs to this category of parameterised models. In the OSPM, concentrations of exhaust gases are calculated using a combination of a plume model for the direct contribution and a box model for the recirculating part of the pollutants in the street. Parameterisation of flow and dispersion conditions in street canyons was deduced from extensive analysis of experimental data and model tests. Results of these tests were used to further improve the model performance, especially with regard to different street configurations and a variety of meteorological conditions.     

Structural perturbations of models used in mathematical biology

The paper discusses the importance of understanding structural perturbations of models used in mathematical biology, where we mainly focus on ecology and dynamical systems. We describe first briefly the classical modeling strategy and the derivation of model structures. Structural perturbations are then discussed, mainly in the framework of ODEs. We give some examples how insights obtained from this type of model could be transfered to other kinds of models. Finally we propose an alternative modeling strategy characterized by a systematic investigation of a models neighbourhood in an appropriately chosen model class.     

高速公路交通噪声预测模型探讨

针对我国当前广泛使用的2种高速公路噪声预测模型《06规范》预测模型与《09导则》预测模型在预测时比较研究,重点利用环境现状监测数据分别对2种模型验证与对比分析.结果表明,2种模型预测值与实测值相差3dB ～5dB,车流量＞ 300辆/h,《09导则》更接近实测值；在夜间车流量＜300辆/h,《06规范》更接近实测值,2种模型结合采用《06规范》计算的车速,距离衰减考虑车流量的大小,在此基础上应用《09导则》,预测结果与实测值更为接近.     

The inadequacy of monitoring without modelling support

There is much to gain in joining monitoring and modelling efforts, especially in the present process of implementing the European Water Framework Directive and in the coming implementation of the Groundwater Directive. Nevertheless, present practises in the water management world suggest that most often models are not considered an option when monitoring obligations in the WFD are solved. The present paper analyses the constraints, such as perceived insufficiency of data for modelling, lack of explicit requirement for modelling in the WFD and its associated technical guidance documents, lack of awareness about what models can do and lack of confidence in models by water managers and policy makers. The findings have mainly emerged from a series of Harmoni-CA workshops aiming at bringing the monitoring and modelling communities together for a discussion of benefits and constraints in the joint use of monitoring and modelling. The workshops were attended by scientists, water managers, policy makers, stakeholders and consultants. The overall conclusion is that modelling can significantly improve the benefits of monitoring data; by quality assurance of data, interpolation and extrapolation in space and time, development of process understanding (conceptual models), and the assessment of impacts of pressures and effects of programmes of measures.     

WARM: a European model for energy and environmental analysis

This paper describes the structure of a newly developed econometric, imperfectly competitive, general equilibrium model for the medium term study of energy and environmental problems. The geographical coverage of the model regards twelve European countries as well as the European Union as a whole. Compared to existing quantitative E3 (economy-energy-environment) models, the WARM model is characterized by a few novel and relevant features Firstly, in contrast to multicountry interlinked models, it copes with the international dimension by integrating differences from a common European denominator within a unified and homogeneously designed framework. A panel data estimation approach is used to achieve this objective. Secondly, in contrast to the traditional market-based philosophy of many econometric models, it adopts a perspective focused upon economic agents' decisions. Thirdly, in contrast with the practice of modelling technical progress as an exogenous and deterministic phenomenon, it incorporates an explicit attempt of modelling the sources and effects of endogenous technical change. A Kalman filter latent variable approach is the methodology from which statistical information on the dynamics of technical progress can be obtained. Finally, all markets in the model are imperfectly competitive, including the labour market where the wage bargaining process is explicitly modelled and estimated. This last feature is especially important in view of the European unemployment problem.