Papers by Darko Joksimovic
Blue-green systems, Sep 28, 2022
Blue-green and blue roofs are increasingly promoted to adapt to climate change by providing multi... more Blue-green and blue roofs are increasingly promoted to adapt to climate change by providing multiple benefits. However, uncertainties about their design and how they differ from conventional green roofs hinder their implementation. This study investigates the potential of green, blue-green, and blue roofs to control urban stormwater and improve microclimate by monitoring their performance in Toronto, Ontario, Canada. Experimental setups were built and varied with the following design factors: substrate type and thickness, drainage layer thickness and orifice size. The results revealed that blue-green roofs with organic and FLL (blended according to the German Forschungsgesellschaft Landschaftsentiwicklung Landschaftsbau) substrates significantly improved detention compared to green roofs with similar substrates. The organic blue-green roof achieved maximum retention, but FLL blue-green roof did not have higher retention than FLL green roof. The blue roof with smaller orifices had comparable hydrologic performance to vegetated roofs but suffered from long water standing durations. Organic substrates followed by FLL substrates result in the highest air cooling in the noon, but blue roofs had the highest air cooling in the evening. In-substrate temperatures in blue-green roofs were lower than those in green roofs. Trade-offs between the benefits and drawbacks need to be considered in future designs.
Journal of Hydrologic Engineering, Mar 1, 2023
Water Science & Technology
A faecal transport model was applied to a 11.3 km2 wastewater servicing area in Toronto, Ontario,... more A faecal transport model was applied to a 11.3 km2 wastewater servicing area in Toronto, Ontario, Canada to explore the role that different wastewater sampling campaigns have on estimating the prevalence of SARS-CoV-2 in a population of 60,000. A stochastic wastewater and water quality model was used to evaluate the effectiveness of 11 sampling campaigns during periods of high and low COVID-19 infection among the population, tested using virtual sampling during dry-weather flow. The virtual sampling campaigns were based on the most common automatic sampler programming capabilities and widely used wastewater-based epidemiology (WBE) sampling campaigns reported in the literature. Sampling campaigns differ in weighting method (time, volume, or flow-weighted sampling), sample count, collection period, or sample time. Results suggest that grab samples should be avoided and/or that sampling campaigns with the greatest sample counts and durations are the most robust at capturing COVID-19 i...
IOCAG 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Water
Conventional green roofs have been widely accepted as a climate change adaptation strategy. Howev... more Conventional green roofs have been widely accepted as a climate change adaptation strategy. However, little is known about the potential of blue–green roofs and rooftop farms to control urban stormwater and improve microclimates. This study evaluates a farmed blue–green roof’s hydrologic and thermal performance over an entire growing season in Toronto, Ontario, Canada. The runoff discharge from three plots planted with various crops was monitored. The substrate and air temperatures at two elevations of different cultivated and self-sowing plant species were collected and compared to a control roof. Results indicate that planting and harvesting activities impacted the hydrologic performance. Mean values for retention ranged from 85–88%, peak attenuation ranged from 82–85%, and peak delay ranged from 7.7 to 8 h. At the lower elevation, the mean air temperature difference above okra, tobacco, and beet was 2.5 °C, whereas, above squash, potato, and milkweed, it was 1.4 °C. Maximum and m...
Recreational water users may be exposed to elevated pathogen levels that originate from various p... more Recreational water users may be exposed to elevated pathogen levels that originate from various point and non-point sources. Current daily notifications practice depends on microbial analysis of indicator organisms (persistence model) such as Escherichia coli (E. coli) that require 18-24 hours to provide sufficient response. This research evaluated the use of Artificial Neural Networks (ANNs) and Evolutionary Polynomial Regression (EPR) for real time prediction of E. coli concentration in water at beaches in Toronto, Ontario, Canada. The nowcasting models were developed using readily available real-time environmental and hydro-meteorological data available for four bathing seasons (June-August). The results of the developed models were compared with historic data and found that the predictions of E. coli levels generated by ANN models slightly outperformed those generated using EPR. The best performing ANN models are able to predict up to 74% of the E. coli concentrations, offering an improvement over the currently employed persistence approach.
Desalination, Jan 5, 2008
In the framework of the international project “Integrated Concepts for Water Reuse”(Aquarec), an ... more In the framework of the international project “Integrated Concepts for Water Reuse”(Aquarec), an independent task-force composed by water and wastewater utilities professionals, consultants and researchers was assigned the task and produced a manual of management practices for water reuse schemes. This paper aims to give an overview of water reuse activities around the world and to outline the specific characteristics of every sectoral use.
Blue-Green Systems, 2021
Blue-Green Infrastructure (BGI) consists of natural and semi-natural systems implemented to mitig... more Blue-Green Infrastructure (BGI) consists of natural and semi-natural systems implemented to mitigate climate change impacts in urban areas, including elevated air temperatures and flooding. This study is a state-of-the-art review that presents recent research on BGI by identifying and critically evaluating published studies that considered urban heat island mitigation and stormwater management as potential benefits. Thirty-two records were included in the review, with the majority of studies published after 2015. Findings indicate that BGI effectively controls urban runoff and mitigates urban heat, with the literature being slightly more focused on stormwater management than urban heat island mitigation. Among BGI, the studies on blue- and blue-green roofs focused on one benefit at a time (i.e. thermal or hydrologic performance) and did not consider promoting multiple benefits simultaneously. Two-thirds of the selected studies were performed on a large urban scale, with computer mod...
Procedia Engineering, 2014
Stormwater management has focused increasingly on Low Impact Development (LID) techniques in rece... more Stormwater management has focused increasingly on Low Impact Development (LID) techniques in recent years. Although their effectiveness has been demonstrated in a number of cases, methodologies for the selection of most appropriate solutions for individual sites are still evolving. The cost efficiency of implementing a wide range of LID techniques in a proposed land development in the City of London, Ontario, Canada was investigated using continuous hydrologic simulation and a recently developed LID costing tool. The results indicate that infiltration trench and infiltration trench in combination with green roof were the most cost efficient solutions for runoff reduction.
Desalination, 2006
In Europe the last two decades has witnessed growing water stress, both in terms of water scarcit... more In Europe the last two decades has witnessed growing water stress, both in terms of water scarcity and quality deterioration, which has prompted many municipalities to look for a more efficient use of water resources, including a more widespread acceptance of water reuse practices. This paper reviews European water reuse practices and sets out the map of the water reclamation technologies and reuse applications. The data are based on a conventional literature survey, on the preliminary evaluation of an in-depth survey of a large number of European water reuse projects and on the findings of a dedicated international workshop. The preliminary evaluation indicates that for an increased utilisation of reclaimed wastewater, clearer institutional arrangements, more dedicated economic instruments and the set-up of water reuse guidelines are needed. Technological innovation and the establishment of a best practice framework will help, but even more, a change is needed in the underlying stakeholders' perception of the water cycle.
The electric power industry worldwide has been focusing towards increasing utilization of renewab... more The electric power industry worldwide has been focusing towards increasing utilization of renewable energy resources such as wind and solar to build and maintain clean, reliable and affordable electricity systems. Although these resources are environmentally clean, their uncertain and intermittent nature is a significant issue. Similarly, other energy generators such as nuclear and gas have serious environmental issues. These issues can be resolved with effective management of supply and demand using appropriate energy storage. Although various energy storage options are available, PHES is globally proven technology at grid level. Additionally, gravity power module (GPM) is a newly emerged technology in the power industry. However, its applications at full scale are still awaited. This research developed methodologies for integrated planning framework for PHES systems at grid level, employing a GIS-based model to identify feasible PHES sites, optimizing the scheduling of feasible PH...
Canada releases over 150 billion litres of untreated and undertreated wastewater into the water e... more Canada releases over 150 billion litres of untreated and undertreated wastewater into the water environment every year. To clean up urban wastewater, new Federal Wastewater Systems Effluent Regulations (the Regulation) on establishing national baseline effluent quality standards that are achievable through secondary wastewater treatment were enacted on July 18, 2012. With respect to the wastewater from the combined sewer overflows (CSO), the Regulations require municipalities to report the annual quantity and frequency of effluent discharges. The City of Toronto currently has about 300 CSO locations within an area of approximately 16,550 hectares. There are about 3,450 km of total sewer length and 51,100 manholes in the CSO area. A system-wide monitoring of all CSO locations has never been undertaken due to the cost and practicality. Instead, the City has relied on estimation methods and modelling approaches in the past to allow funds that would otherwise be used for monitoring to be applied to reduce CSOs' impacts. The City is now undertaking a study by using the approach of GIS-based hydrologic and hydraulic modelling. Results show the usefulness of this for 1) determining the flows contributing to the combined sewer system in local and trunk sewers for dry weather flow and wet weather flow; 2) assessing and predicting hydraulic grade line and surface water depth in all local and trunk sewers under heavy rain events; 3) analyzing local and trunk sewer capacities for future growth; and 4) estimating annual quantity and frequency of CSOs at each CSO locations.. This modelling approach has also allowed funds to be applied toward reducing and ultimately eliminating the adverse impacts of CSOs rather than expending resources on unnecessary and costly monitoring.
Consulting engineers, conservation authorities, and municipalities are looking for methods of sto... more Consulting engineers, conservation authorities, and municipalities are looking for methods of stormwater management control that not only restore pre-development hydrological cycles, but also offer the benefit of runoff quality treatment. As a result, Low Impact Development (LID) approaches, which are often applied at the source, have been gaining in popularity. The objective of this research is to develop guidance for the design of bioretention cells for runoff water quality treatment, evaluating bioretention cells’ ability to perform such treatment function through modelling. A number of different modelling tools have been developed to simulate the performance of bioretention cells. These models are utilized to aid in the analysis of how bioretention cell design and layout affect the runoff treatment, for the purpose of providing engineering guidance on the optimal design of bioretention cells for stormwater runoff quality enhancements.
This thesis is available for Library use on the understanding that it is copyright material and t... more This thesis is available for Library use on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement. I certify that all material in this thesis which is not my own work has been identified and that no material has previously been submitted and approved for the award of a degree by this or any other University.
Proceedings
Wastewater is an abundant and an underutilized thermal energy source that experiences steady temp... more Wastewater is an abundant and an underutilized thermal energy source that experiences steady temperatures and predictable flow rates year-round. These characteristics make it an excellent candidate to serve as the heat source and sink for heat pump based HVAC (Heating, Ventilation, and Air Conditioning) systems capable of providing both heating and cooling. The potential for wastewater heat recovery is evaluated for a large hospital in the greater Toronto area, in Canada. A model was developed to calculate the operational savings and benefits of the proposed system, and the results from that analysis were used to carry out an economic analysis.
ACKNOWLEDGEMENTS LIST OF TABLES LIST OF FIGURES LIST OF APPENDICES 1.1 Intfoduc tion 1.1.1 Non-st... more ACKNOWLEDGEMENTS LIST OF TABLES LIST OF FIGURES LIST OF APPENDICES 1.1 Intfoduc tion 1.1.1 Non-structural Contmls 1.1.2 Source Controls 1.1.3 Conveyance System Controls 1-1.4 End of Pipe Controls 1.2 Real Time Control 1.2-1 TypesandModesofContrd 1.2.2 Evaluating Potential of Real Time Control 1.2.3 Modelling Requirements and Existing Models 1 -3 Research Objectives and Thesis Outline CHAPTER 2 ibUiWALL MODULE 2.1 Continuous Rainf" Input to Urban Drainage Models 2.2 Generating Synthetic Rainfd Senes 2.3 Rainfall Event Representatioa 2.4 R a i n f i Record Analysis 2.4.1 Correlation and Trends 2.4.2 Probability Distniution of Rainfall Characteristics 2-4-2-1 Marginal Distriiutions 2.4.2.2 Joint Distriibutions 2.4.2.3 Conditional Distriiutious 2.5 Random Number Generators 2.5.1 Uniform Distniution 2.5.2 Univariate Expoueutid Distribution 2.5.3 Univariate Gamma Dism'bution 2.5.4 Bivariate Gamma Distn'bution 2.5.5 Univariate Standard Normal Distnibution 2.5.6 Multivariate St...
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Papers by Darko Joksimovic