Urban Institute Ireland Research Collection
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Browsing Urban Institute Ireland Research Collection by Author "Bruen, Michael"
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- PublicationThe COST 731 Action : a review on uncertainty propagation in advanced hydro-meteorological forecast systems(Elsevier, 2010-05)
; ; ; ; ; ; ; Quantifying uncertainty in flood forecasting is a difficult task, given the multiple and strongly nonlinear model components involved in such a system. Much effort has been and is being invested in the quest of dealing with uncertain precipitation observations and forecasts and the propagation of such uncertainties through hydrological and hydraulic models predicting river discharges and risk for inundation. The COST 731 Action is one of these and constitutes a European initiative which deals with the quantification of forecast uncertainty in hydro-meteorological forecast systems. COST 731 addresses three major lines of development: (1) combining meteorological and hydrological models to form a forecast chain, (2) propagating uncertainty information through this chain and make it available to end users in a suitable form, (3) advancing high-resolution numerical weather prediction precipitation forecasts by using non-conventional observations from, for instance, radar to determine details in the initial conditions on scales smaller than what can be resolved by conventional observing systems. Recognizing the interdisciplinarity of the challenge COST 731 has organized its work forming Working Groups at the interfaces between the different scientific disciplines involved, i.e. between observation and atmospheric (and hydrological) modeling (WG-1), between atmospheric and hydrologic modelling (WG-2) and between hydrologic modelling and end-users (WG-3). This paper summarizes the COST 731 activities and its context, provides a review of the recent progress made in dealing with uncertainties in flood forecasting, and sets the scene for the papers of this Thematic Issue. In particular, a bibliometric analysis highlights the strong recent increase in addressing the uncertainty analysis in flood forecasting from an integrated perspective. Such a perspective necessarily involves the area of meteorology, hydrology, and decision making in order to take operational advantage of the scientific progress, an aspect in which COST 731 is successfully contributing to furthering the flood damage mitigation capabilities in Europe.Scopus© Citations 68 2174 - PublicationDesigning for surface water runoff control : end-user requirements in Ireland(Copernicus Publications, 2008-07)
; ; ; Since 1975, flood estimation in Ireland has generally followed methods as outlined in the Flood Studies Report (Natural Environment Research Council, 1975). An update of this for conditions in the Republic of Ireland commenced in 2005 and included research in Urban Catchment Flood Analysis. To inform this work, a scoping study of issues relating to flooding caused by urban runoff was undertaken by a team from the Centre for Water Resources Research at University College Dublin and some of the findings are described in this paper. It focussed on quantitative and qualitative research methods (self-completion questionnaires and Focus Groups) to review the methods of flood estimation for urbanised catchments currently in use in Ireland. It assessed the nature of deficiencies associated with urban-runoff control and identified achievable and realistic objectives for further research. A questionnaire was developed around a number of key themes pertaining to flooding caused by urban runoff and circulated to 291 stakeholders in target sectors that ranged from Engineering Consultancies to Academic Institutions. A total of 100 questionnaires were returned giving a 34% response rate. The study found; (i) a proliferation of methods are used in practice resulting in significant differences between the estimates; (ii) some methods are sometimes being used for inappropriate spatial scales; (iii) there is a lack of clear guidance on the use of the methods and/or associated software packages; (iv) there is little appreciation of the uncertainties associated with the methods and (v) there are significant deficiencies in some of the basic information available. A list of recommendations was produced, to guide the commissioning of future research to improve the methods available to designers.Scopus© Citations 1 1089 - PublicationEffectiveness of a drinking-water treatment sludge in removing different phosphorus species from aqueous solutionDrinking-water treatment sludge (DWTS) produced at water treatment plants is an inescapable by-product and has long been treated as a waste for landfill. In this study, a series of batch adsorption tests were conducted using a wide range of phosphorus (P) species to determine the adsorption capacities of freshly dewatered aluminium salt based DWTS. The adsorption process is highly dependant on the pH of the suspension and is good at low pHs with adsorption capacities in the order of orthophosphate>polyphosphate>organic phosphate when these three P species were simulated according to their level in typical municipal wastewater. At pH 4.0, the adsorption capacity for orthophosphate was 10.2 mg-PO43-/g DWTS, polyphosphate was 7.4 mg-PO43-/g DWTS and organic phosphate was 4.8 mg-PO43-/g DWTS. Subsequently, a continuous flow column test with dewatered Al-based DWTS as filter medium was conducted at a hydraulic loading of 2.79 m3/m2.d and an extremely high P loading of 210.5 PO43-/m2.d. The sludge bed remained stable and removed over 80% P in a 30 day period and the bed did not reach saturation point for over 60 days. This proves the potential of the sludge as a filter material in various forms of P immobilization, thus converting it from a waste to a useful material in pollutant control.
Scopus© Citations 188 4570 - PublicationEutrophication from agricultural sources(Environmental Protection Agency, 2008)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; 1153 - PublicationAn evaluation of urban flood estimation methodologies in Ireland(Wiley and Chartered Institution of Water and Environmental Management (CIWEM), 2010-03)
; ; ; This paper summarises the findings of a study to evaluate the use in Ireland of the different flood estimation methodologies that can be applied to urban or urbanising catchments. The study, undertaken as part of the Office of Public Works‟ (OPW) Flood Studies Update programme, comprised both quantitative (posted questionnaires) and qualitative research (focus groups) targeting a range of organisations involved with planning and design issues pertaining to urban flooding. A total of 291 questionnaires was circulated. Of these, 100 were returned, equating to a response rate of 34%. Results indicate that formulae and methods for determining runoff rates in urban and urbanising catchments are being applied very generally without due consideration being given to the statistical foundation underlying the methods. The resulting inconsistencies in estimated runoff rates highlight the need for National Guidance for flow estimation in urban and urbanising catchments in Ireland.Scopus© Citations 4 3983 - PublicationHydrology and the Water Framework Directive in IrelandThe Water Framework Directive has been the catalyst for a considerable amount of data collection, analysis and research covering a wide range of physical and biological characteristics and involving a wide range of scientific, social and management related disciplines. This paper starts with a short description of the discipline of hydrology and then identifies the main hydrological aspects of work for the WFD and notes their ecological significance. Some idea is given of the range of organisations and disciplines involved in the work and of the links between them. Of particular significance is the degree of cooperation between River Basin Districts in setting up working groups for special studies, avoiding overlaps in research.
Scopus© Citations 5 3232 - PublicationResponse surface optimization of phosphorus species adsorption onto powdered alum sludgeThe purpose of this study is to optimize adsorption conditions of powdered alum sludge (PAS) as low-cost adsorbent for the removal of three P-species (ortho-P, poly-P and organic-P) from wastewater using the response surface methodology (RSM). Initially, RSM in the basis of a three-variable Box-Behnken design was used to determine the effect of pH (from 4 to 7), PAS mass (from 0.1 to 0.5 g) and PAS particle size (from 125 to 420 μm) on the response levels (removal efficiencies of the three P-species). Three response surface quadratic models in terms of three factors were then obtained from an analysis of the experimental data using a SAS computer package. Thereafter, the effect of each of the parameters on P removal for each of the three species was examined using the three-dimensional response surface. All three parameters (pH, PAS mass and PAS particle size) had a significant effect on the removal of each of the P species. Finally, optimal conditions for P species removal were determined at which the P-removals of 99.8 % (for ortho-P), 94.9 % (for poly-P) and 94.8 % (for organic-P) were achieved, respectively. The results derived from the verification experiments agreed with that predicted by the models, confirming the suitability of the established models and the success of RSM in optimizing the PAS adsorption conditions.
Scopus© Citations 10 2926 - PublicationReuse of aluminium-based water treatment sludge to immobilize a wide range of phosphorus contamination : equilibrium study with different isotherm models(Taylor & Francis, 2007-10)
; ; ; ; The adsorption equilibrium of a wide range of phosphorus species by an aluminium-based water treatment sludge (Al-WTS) was examined in this study. Four kinds of adsorption-isotherm models, namely Langmuir, Freundlich, Temkin and Dubinin-Radushkevich, were used to fit the adsorption equilibrium data. In order to optimise the adsorption-isotherm model, correlation coefficient (R2) and four error functions were employed to facilitate the evaluation of fitting accuracy. Experiments have demonstrated that the Al-WTS may be an excellent raw material to adsorb P in polluted aqueous environment with adsorption ability in the order of KH2PO4 (ortho-P) > Na(PO3)6 (poly-P) > C10H14N5O7P·H2O (organic-P). More importantly, this study provides an entire comparison of the four isotherms in describing the P adsorption behaviour. By considering both the standard least-square based R2 and the results of four error functions analysis, this study reveals that the Freundlich isotherm appears to be the best model to fit the experimental equilibrium data. Langmuir and Temkin isotherms are also good models in current experimental conditions while Dubinin-Radushkevich isotherm poorly described the adsorption behaviour. The error analysis in this study provides vital evidence to reflect its role in facilitating the optimisation in adsorption isotherm study. Obviously, R2 seems inadequate in optimising multi-isotherm models due to its inherent bias resulting from the least-squares linearisation.Scopus© Citations 37 2974 - PublicationTechnical assessment and evaluation of environmental models and software : letter to the Editor(Elsevier, 2011-03)
; ; ; ; ; ; ; ; ; ; ; ; ; ; This letter details the collective views of a number of independent researchers on the technical assessment and evaluation of environmental models and software. The purpose is to stimulate debate and initiate action that leads to an improved quality of model development and evaluation, so increasing the capacity for models to have positive outcomes from their use. As such, we emphasize the relationship between the model evaluation process and credibility with stakeholders (including funding agencies) with a view to ensure continued support for modelling efforts. Many journals, including EM&S, publish the results of environmental modelling studies and must judge the work and the submitted papers based solely on the material that the authors have chosen to present and on how they present it. There is considerable variation in how this is done with the consequent risk of considerable variation in the quality and usefulness of the resulting publication. Part of the problem is that the review process is reactive, responding to the submitted manuscript. In this letter, we attempt to be proactive and give guidelines for researchers, authors and reviewers as to what constitutes best practice in presenting environmental modelling results. This is a unique contribution to the organisation and practice of model-based research and the communication of its results that will benefit the entire environmental modelling community. For a start, our view is that the community of environmental modellers should have a common vision of minimum standards that an environmental model must meet. A common vision of what a good model should be is expressed in various guidelines on Good Modelling Practice. The guidelines prompt modellers to codify their practice and to be more rigorous in their model testing. Our statement within this letter deals with another aspect of the issue – it prompts professional journals to codify the peer-review process. Introducing a more formalized approach to peer-review may discourage reviewers from accepting invitations to review given the additional time and labour requirements. The burden of proving model credibility is thus shifted to the authors. Here we discuss how to reduce this burden by selecting realistic evaluation criteria and conclude by advocating the use of standardized evaluation tools as this is a key issue that needs to be tackled.Scopus© Citations 63 3164 - PublicationA three-dimensional hydro-environmental model of Dublin BayThis paper compares a 3-dimensional hydro-ecological model with a 2-dimensional model simulating the distribution and fate of Escherichia Coli (E.Coli) discharges from a sewage treatment plant discharging into Dublin Bay, Ireland. Before being discharged, the effluent from the sewage treatment plant is mixed with cooling water from a thermal generation plant resulting in a warm buoyant sewage plume that can be 7 − 9oC higher than the ambient water in the Bay. The mixing of the stratified plume is complicated by the tidal currents which transport the plume into and out of the estuary. These processes have a direct impact on the transport and fate of E.Coli and the model comparison demonstrates that a three-dimensional model is required to adequately represent the mixing processes in such a stratified environment. The modelling followed a two-step procedure. First, hydrodynamic simulations of water levels and flow velocities in Dublin Bay were performed using the three-dimensional model TELEMAC-3D. The resulting water level and flow velocity fields were used by the three-dimensional water quality model, SUBIEF-3D to model the transport and fate of E.Coli in the Bay. Further simulations were performed in which the wind effects on the E.Coli dispersion were included. The water quality simulation was repeated using the 2-dimensional, depth-averaged, hydrodynamic model TELEMAC-2D to compare with the three-dimensional simulations. The results showed that the three-dimensional model gives an adequate representation of the hydrodynamics and water quality in the Bay while the two-dimensional, depth-averaged, water quality model (in comparison to the three-dimensional model) delays the timing of the delivery of E.Coli to the Bay and seriously underestimats the decay rate of E.Coli and the effect of wind on the movement of the buoyant plume of pollution.
Scopus© Citations 26 2620 - PublicationWater Framework Directive - integration, negotiation and communication of optimal measures with stakeholders (WINCOMS) : STRIVE report(Environmental Protection Agency, 2006-12)
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