Modelling and simulation framework for reactive transport of organic contaminants in bed-sediments using a pure java object - oriented paradigm

Numerical modelling and simulation of organic contaminant reactive transport in the environment is being increasingly relied upon for a wide range of tasks associated with risk-based decision-making, such as prediction of contaminant profiles, optimisation of remediation methods, and monitoring of changes resulting from an implemented remediation scheme. The lack of integration of multiple mechanistic models to a single modelling framework, however, has prevented the field of reactive transport modelling in bed-sediments from developing a cohesive understanding of contaminant fate and behaviour in the aquatic sediment environment. This paper will investigate the problems involved in the model integration process, discuss modelling and software development approaches, and present preliminary results from use of CORETRANS, a predictive modelling framework that simulates 1-dimensional organic contaminant reaction and transport in bed-sediments

Lean interfaces for integrated catchment management models: rapid development using ICMS

A move towards the development of lean, issue-focused interfaces is being explored to provide a rapid delivery mechanism to transfer catchment science to managers and custodians. This approach is a move away from development of large decision support systems which attempt to anticipate a myriad of management questions. It relies on having a modelling system which supports the rapid building and integration of catchment models, and is independent of the interface. ICMS (Interactive Component Modelling System) is a PC-based software tool which has been developed with this in mind. The kernel of the ICMS system, ICMSBuilder, provides the modeller’s view of the world, on top of which can be built any number of interfaces which provide the targetted audience’s view of the world. This paper presents an ICMS prototype to demonstrate the power and flexibility of such an approach. It describes an ICMS project - a suite of linked models which explore the relationships between hydrology, water allocation and extraction rules, and on-farm decision making; and an ICMS View - an interface for that project tailored to address specific management scenarios. Interestingly, the ability to interact with parts of the models through the View gave managers the confidence to delve into the underlying models and data, something often denied to them by traditional decision support systems

Integrating hydrology and ecology models into flexible and adaptive decision support tools: the IBIS DSS

Terminal wetlands in the semi-arid regions of northern NSW are important ecological refuges for native fauna, especially during dry times. Many of these systems have become increasingly stressed by human induced changes in the hydrologic regime of the rivers flowing into the lakes. For example, the Narran Lakes is a Ramsar wetland recognised for its geomorphological significance and the importance of the system as habitat and drought refuges for waterbirds and other species. The high level of regulation in the headwaters of the lake poses considerable obstacles for managers responsible for managing the health of the Narran Lakes

La ingeniería de software como vehículo para la planificación ambiental de los recursos hídricos

Software engineering is an important discipline of knowledge that allows abstracting an environmental system, modeling a watershed and providing conceptual and interaction elements  of players in the configuration of modeling approaches for decision-making on water resources environmental planning; therefore, the purpose of this article is to have anenvironment envelopethrough a set of environmental aspects that can be represented by a meta-model that leads to a cognitive constructof the problemand defines the methodological model for proper environmental planning of watersheds, in decision-making at strategic and operational levels. La ingeniería del software es una importante disciplina de conocimiento que permite abstraer un sistema ambiental, modelar una cuenca y proporcionar elementos conceptuales y de interacción de los jugadores en la configuración de enfoques de modelado para la toma de decisiones sobre planificación ambiental de los recursos hídricos; por lo tanto, el propósito de este artículo es tener una envolvente ambiental a través de un conjunto de aspectos ambientales que puedan representarse mediante un metamodelo que conduzca a una construcción cognitiva del problema y definir el modelo metodológico para la planificación ambiental adecuada de las cuencas hidrográficas, en la toma de decisiones en niveles estratégicos y operacionales. 

Rainfall-runoff modelling : comparison of modelling strategies with a focus on ungauged predictions and model integration

This work is an integrative study of methods for rainfall-runoff simulation. The thesis addresses process description considerations, problems associated with ungauged predictions, and tools for sharing data and computational procedures over the Internet. Simple runoff model structures can be preferred as they facilitate systematic uncertainty assessments and can fit streamflow data as well as more complex structures. A more complex model structure can be invoked when assessing hydrological problems involving water quality considerations, which often necessitates explicit representation of runoff generation mechanisms and different flow pathways. Models that have more ambitious objectives than merely to reproduce streamflow should also be validated against other measured data than just flow records. It is demonstrated that two different model parameterisations can yield both good quality fits to observed streamflow data, but generate drastically different evapotranspiration time series. This thesis also presents a case study where a physics-based hydrological model is calibrated and validated using groundwater levels and isotope tracer results. Runoff predictions for a catchment lacking streamflow records can be based on establishing relationships between physical catchment attributes and runoff model parameters using flow data from other catchments belonging to the same region. Results of this thesis suggest that consideration of correlation among runoff model parameters can improve performance of such a regionalisation exercise. Ideally, one would wish to exploit available information on catchment properties in a more physics-based way where observed values of physical catchment properties are incorporated into the model structure and parameters directly. Although physics-based models still face problems which are not readily solvable, results of this study show some promise in predicting streamflow in a physically more consistent way with a minimum amount of parameter calibration. The final part of this thesis explores tools for distribution of environmental data sets and simulation models over the Internet. The idea is to promote openness in environmental simulation studies by providing means for data and model integration from resources published by different parties.reviewe

Numerical modelling of organic contaminant reaction and transport in bed-sediments.

Reactive transport modelling of contaminants in the environment is being increasingly relied upon for a wide range of tasks associated with risk-based decision making, such as interpretation of historical contamination data, optimisation of attenuation and remediation methods, and monitoring of changes resulting from an implemented remediation scheme. However, in the area of contaminant fate and behaviour in bed-sediments, reactive transport modelling has until now stopped short of integration of various mechanistic models to a single modelling environment that would allow a cohesive understanding and prediction of contaminant profiles. This study has developed CoReTranS, a predictive modelling environment that simulates one-dimensional organic contaminant reaction and transport in bed- sediments, using an object-oriented modelling approach. The CoReTranS model has been verified and benchmarked by comparing numerical results of simplified problems with their analytical solutions. The following simulations were undertaken to validate the CoReTranS model: 1. Simulation of the dataset from a diffusion-controlled laboratory experiment for the transport and distribution of selected trace level organic contaminants in a riverine environment gave new numerical results to improve on predicted modelling approach. 2. Simulation of the dataset from a study of marsh sediments contaminated with petroleum-derived hydrocarbons from Wild Harbour, West Falmouth, MA and Kitimat Arm, Douglas Channel, British Columbia resulted in an excellent agreement between the numerical results of the transport model in CoReTranS and the numerical results and data of the original study. The CoReTranS model was also used to interpret results from the following field studies in order to explain key processes that controlled the fate and transport of PAHs and PCBs in bed-sediments: 1. Simulation of the dataset from Kitimat fjord system near Kitimat, British Columbia, wherein PAHs in sediments were purported to be derived from atmospheric particle emissions, wastewater discharges and accidental spillages from a nearby duminium smelter provided a better understanding of the post-depositional reactive transport of PAHs in the fjord system. 2. Simulation of the dataset from a study on the natural recovery of PCB-contaminated sediments at the Sangamo-Weston/Twelvemile Creek/Lake Hartwell Superfund Site in the US showed that it would take nearly 30 years to achieve the 1 mg/kg clean-up goal for total PCB in the chosen transect sites, and 20 years more than the predicted time in the original study. The CoReTrans model was also used to predict the effect of capping contaminated sediments as a remedial strategy. Results from the various simulation scenarios using the CoReTranS model showed that sediment capping as a remedial strategy in managing contaminated sediments can effectively reduce contaminant flux to the overlying water through interaction with the sediment cap matrix and by increasing the dissolved contaminants' transport lengths (i.e., cap thickness). Comparing the results obtained from laboratory experiments or field monitoring studies of bed-sediment systems with different accumulation, degradation and release mechanisms, with the results from the CoReTranS model was critical in identifying the key processes that drive the fate and transport of organic contaminants in bed-sediments. The information derived from the use of the CoReTranS model highlighted recommendations to guide future experiments, field monitoring and model extension which include other relevant transport mechanisms such as colloid- enhanced transport, rate-limited reaction processes and the effect of sediment consolidation to contaminant fate and transport. This information will further enable practical application of such information by engineers to site-specific risk assessment and remediation, as well as continued research and technology development

Analysis and modelling of the flood pulse and vegetation productivity response in floodplain wetlands

This thesis aims to develop a conceptual understanding of the flooding patterns and vegetation response of large floodplain wetlands and to develop an inundation and vegetation response model for water management. Applicable to a range of floodplain wetland systems, the conceptual node-network approach was developed in relation to the Gwydir wetlands, NSW, Australia. The Gwydir floodplains and wetlands occur in a dryland setting and are reliant on flows from the upstream catchment that has substantial water resource development. The Gwydir wetlands include a range of ecological values and are listed under international agreements for the protection of wetlands and migratory waterbirds. The challenge of understanding flooding patterns in the Gwydir wetlands are common to other floodplain systems where shallow inundation, rapid vegetation growth and canopy cover may preclude the assessment of open water flooding from conventional remote sensing techniques. To characterise the flooding patterns a multi-temporal decision tree approach was developed. Based on classification of flooding as open water or from the subsequent high vigour vegetation response, the method uses remotely sensed vegetation indices to map a range of flood events. The results are summarised into homogenous patches with respect to flood frequency and connectivity. Using the patch analysis and assessment of connectivity between the patches and channels, the floodplain wetlands were conceptualised using a node-network model of the 17 patches. Patches were categorised according to vegetation associations and the resulting landscape units used to develop models of vegetation productivity response measured as the fraction of photosynthetically active radiation (fPAR). Phenological attributes such as greenup, maturity, senescence and dormancy were extracted from the time series fPAR to characterise landscape units, and the fPAR response to inflow and soil moisture was modelled. Multiple linear regression models show significant relationship with inflows for many of the wetland landscape units. The node-network and fPAR models are combined to develop the Inundation and Vegetation Response Model (IVRM) that provides a means of distributing river inflow and climate variables across the landscape and linking these to vegetation productivity response. Sensitivity testing is undertaken for uncertain parameters and further research needs identified. The model is applied to predicting inundation and vegetation response outcomes from predevelopment, current development and future climate change (2030) scenarios. Results suggested that in the most frequently flooded patch, inundation could have occurred over 99% of the time under the predevelopment scenario, compared to less than 63% of the time under a ‘dry’ prediction of future climate change. This thesis integrates hydrological and ecological understanding, remote sensing analysis, statistical methods, and good modelling practice to develop the IVRM. The assessment framework takes a holistic view of an ecosystem, and explores how a wetting regime influences structure and function. The landscape scale approach uses the lateral, temporal and vertical connectivity, critical to the floodplain wetland functioning, to inform the development the model. The spatial and temporal scales are specific to the geomorphology, hydrology and ecology of the case study catchment, but the principles and methods can be applied to floodplain wetland systems in general