BITS Faculty Publications

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Author: search.filters.author.Goonetilleke, AshanthaStart date: 2021

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    Assessing social resilience in disaster management
    (Elsevier, 2021-01) Goonetilleke, Ashantha
    The key challenge in social resilience assessment is to translate abstract and complex concepts to enable its measurement. Existing measures of social resilience indicators are problematic as these do not necessarily account for the multi-faceted and dynamic nature of the indicators. Therefore, innovative and reliable measurement approaches are required to improve the incorporation of social resilience measures in disaster management policy and practice. The adoption of a surrogate approach, which has received limited attention in a disaster management context, can help to overcome the conceptual challenges inherent in measuring such indicators by capturing key facets of the target indicator and facilitate robust social resilience measurement. This manuscript presents a set of potential surrogates for social resilience indicators identified in an exploratory research investigation. The data was collected using a case study approach utilising interviews with disaster practitioners and policy makers. The data analysis revealed six potential surrogates for each social resilience indicator. The identified potential surrogates provide a reliable measure of social resilience in policy and practice to devise appropriate strategies for enhancing social resilience by regularly monitoring and updating the resilience status using locally available administrative data. The potential surrogates identified to measure social resilience indicators can also be replicated with proper contextualisation in different geographic and hazard exposure settings.
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    Treatment technologies for stormwater reuse
    (Elsevier, 2021) Goonetilleke, Ashantha
    Stormwater continues attracting attention as a potential alternative and largely uncommitted source of water for urban areas lacking adequate conventional water resources. However, the presence of a diversity of contaminants suggesting low quality significantly reduces its viability for direct reuse. Therefore, appropriate stormwater treatment is an important scientific and technological challenge in order to reduce the demand for conventional water resources. In this chapter, treatment technologies with the potential for application in the removal of a wide range of contaminants from stormwater are presented along with the identification of current knowledge gaps and recommendations for future research directions.
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    Household attributes, motivational factors, and sources of motivation influencing flood preparedness of vulnerable population groups
    (Higher Education Press, 2026) Goonetilleke, Ashantha
    Extreme disaster events, particularly floods, impact individuals, households, and communities differently depending on a range of factors. Some residents are more vulnerable than others to floods, hence urgent action is needed to improve preparedness of vulnerable groups to reduce potential impacts of flooding. To achieve this, it is important to assess household flood preparedness, and identify the influence of household-level attributes on flood preparedness. Using a large-scale community survey, this study investigated how key household attributes such as evacuation assistance, Internet access, and key motivational factors and sources of motivation such as personal and social networks influence flood preparedness among vulnerable households. Households were categorized into three levels of vulnerability (high, medium, and low) by combining household economic capacity, as measured by household monthly expenditure, and the presence of vulnerable family members. Six key findings emerged: (1) Highly vulnerable households showed higher resilience to floods, and flood preparedness levels are independent of household vulnerability levels; (2) Self-reported household flood preparedness is positively influenced by learning from past disaster experience; (3) Financial and time commitments, and a sense of urgency for household-level flood preparedness are key intrinsic motivational factors that influence flood preparedness; (4) Access to reliable Internet can be used as a proxy to predict the degree of household flood preparedness; (5) Higher levels of awareness and knowledge of flood preparedness were reported despite low levels of community consultation; and (6) Self-motivation is the key source of motivation for flood preparedness. The study findings will support key institutional stakeholders such as local governments to devise strategies to strengthen the flood resilience of vulnerable households and communities.
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    Modelling land use influence on polymer-specific microplastics abundance and transportation from terrestrial to aquatic environments
    (Elsevier, 2026-04) Goonetilleke, Ashantha
    Plastic waste has reached a major environmental crisis level. Human exposure to microplastics (MPs)– particles <5 mm – is linked to toxicity, oxidative stress, inflammatory responses, neoplastic change, and numerous chronic health effects. Effective mitigation requires a thorough understanding of factors that govern MP accumulation and transport. While quantitative analyses at the polymer level remain limited, the role of land use patterns in shaping polymer abundance and movement is especially underexplored. This study addresses this knowledge gap by characterising and quantifying polymer-specific MP abundance (polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) and polyvinyl chloride (PVC)) in freshwater across four urban land uses (industrial, commercial, residential, and natural). Bayesian Network models were developed for two urban catchments, and a pooled model generated generalised estimates across both basins. PET and PP dominate industrial areas, while commercial areas show high PE, PVC, and PS levels. Residential areas contain elevated levels of all five polymers, and the natural regions are characterised by PE, PVC, and PS. These distinct polymer signatures reflect local activities associated with each land use. Regression outputs from the pooled model enabled quantification of individual polymer loads and prediction of concentrations at unsampled sites based on known land use profiles. Strong relationships were found between abundance and commercial/industrial land uses than with residential and natural settings. Consequently, mitigation strategies targeting industrial and commercial sectors will yield the greatest reductions in MP emissions. Study outcomes support targeted source control and efficient monitoring designs, and robust policy development for curbing microplastic pollution.
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    Catchment characteristics and land-use influence on microplastics distribution in freshwater sediments
    (Elsevier, 2026-04) Goonetilleke, Ashantha
    This study examines microplastic contamination in freshwater sediments from three urban creeks in Brisbane, Australia. A dual-density extraction method, validated by recovery experiment (85–100%), was used to extract microplastics, followed by identification via light microscope, micro- FTIR and SEM. Kedron Brook showed the highest median abundance (4400 items/kg), followed by Bulimba Creek (4100 items/kg) and Enoggera Creek (2800 items/kg). Site-wise assessment revealed three distinct spatial patterns among the creeks, likely reflecting differences in runoff dynamics, surrounding anthropogenic activities, catchment elevation profile, and land-use. Microplastics abundances were higher at downstream and estuarine sites, particularly within urbanised zones. Polymer analysis identified polyethylene (PE), polypropylene (PP) and Polymethyl methacrylate (PMMA) as the most dominant types. Linear mixed-effects modelling identified creek system (p = 0.018) and sampling round (p = 0.003) as significant predictors of microplastic abundance, while between-site variability was reflected by a site-level random-effect variance of 0.0116. Multivariate analyses revealed distinct land-use associations, with residential and commercial land-uses significantly associated with PP and polyester, and industrial land-use associated with PP, polystyrene (PS), and polyester, whereas natural land-use showed no significant associations with any polymer type. Overall, urban land-use types exerted a stronger influence compared to natural land-use on microplastic distribution in freshwater sediments.
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    Influence of photolysis on source characterization and health risk of polycyclic aromatic hydrocarbons (PAHs), and carbonyl-, nitro-, hydroxy- PAHs in urban road dust
    (2021-01) Goonetilleke, Ashantha
    In this study, PAHs and their transformed PAH products (TPPs) in road dust were subjected to UV driven photolysis, and then extracted using simultaneous pressurized fluid extraction, and analysed using Shimadzu Triple Quadrupole GC/MS. The results of the analysis were used to investigate the robustness and reliability of 14 existing diagnostic ratios (DRs) and two newly proposed molecular DRs that are relevant for characterizing the sources of PAHs and TPPs. The influence of photolysis on the carcinogenic health risk posed to humans by these hazardous pollutants was then assessed. The findings indicated that the DRs segregated into stable, moderately stable and non-stable classes of source characteristics under the influence of photolysis. Only two of the existing DRs, namely, benzo(a)pyrene/benzo(ghi)perylene (BaP/BghiP) and total index exhibited consistent stability to photolysis, whilst fluoranthene/(fluoranthene + pyrene) (FRT/(FRT+PYR)) showed moderate stability. The two newly proposed DRs, naphthalene/1-nitronaphthalene (NAP/NNAP) and pyrene/(1-nitropyrene + 1-hydroxypyrene) (PYR/(1NPY+HPY)) were found to be highly reliable in post-emission source characterization. The cross-plots of the most stable DRs showed that traffic emissions is the primary source of PAHs, whilst post-emission photolysis is the secondary source of nitro-PAH (NPAH) TPPs. The percent resonance energy thermodynamic stability of the PAH pollutants does not exert any direct influence on the source characteristics of the DRs. Adults are more vulnerable to potential carcinogenic risks as a result of PAH and TPPs photolysis whereas negligible risk exist for children. This study contributes to a more reliable diagnosis of PAH and TPP sources and thus, to the regulatory mitigation of these hazardous pollutants thereby, promoting enhanced protection of human health and the environment.
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    Influence of the hierarchical structure of land use on metals, nutrients and organochlorine pesticides in urban river sediments
    (Elsevier, 2021-01) Goonetilleke, Ashantha
    Land use management plays a key role in mitigating urban river pollution. Past research has addressed how primary land uses influence river water and sediment quality, but has given limited attention to the subdivision of primary land uses to a secondary level, limiting the accurate identification of potential sources of pollutants. The current study, using Bayesian Networks, investigated how the hierarchical structure of land use can be employed to accurately characterise the pollution of sediments in two rivers in China and Australia. It was found that the primary land uses are a weak determinant of potential sources of metals, nutrients, and organochlorine pesticides (OCPs). However, secondary land uses provide higher accuracy in determining pollutant sources. The study highlighted that the lack of data to enable the subdivision of land uses can constrain informed decision making for the mitigation of urban water pollution.
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    Catchment based estimation of pollutant event mean concentration (EMC) and implications for first flush assessment
    (Elsevier, 2021) Goonetilleke, Ashantha
    The Event Mean Concentration (EMC) is considered as a key analytical parameter for assessing the quality of stormwater. The conventional estimation methods to determine EMC do not necessarily address the variability associated with the hydrologic characteristics. Accordingly, this study was conducted to identify the potential hydrologic variables that can influence EMC and thereby to create a mathematical model to determine EMC using the hydrologic variables while incorporating the catchment as an influential factor. This paper introduces an innovative approach to estimate EMC of a runoff event using a stepwise multiple linear regression model. The model incorporates hydrologic variables together with their two-way interaction terms. The catchment was included in the model as a dummy variable. This allows identifying the variability of EMC between catchments. Model can reasonably predict the EMC with an overall prediction error of 0.811. The regression coefficients of the model specify that, maximum rainfall intensity is the most influential variable having a coefficient of 1.008, followed by the average intensity with a coefficient −0.586. The interaction term of rainfall depth and the antecedent dry period indicates that for a relatively small rainfall event (<5 mm), an optimum value of antecedent dry period exists that maximises the EMC. Subsequently, EMC was employed to define the first flush runoff as an alternative approach to the conventional approaches for determining the first flush. The dynamic mean concentration (), was introduced as a parameter for estimating the first flush using EMC. The maximum accumulated runoff volume such that, was defined as the first flush runoff. It was found that residential catchments generate more intense first flush compared to catchments with totally impervious surface areas and thereby a significant pollutant load is transported within a small initial fraction of the runoff.f
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    New conceptualisation of first flush phenomena in urban catchments
    (Elsevier, 2021-03) Goonetilleke, Ashantha
    First flush is an important phenomenon commonlyused in stormwater treatment system design where only the highly concentrated initial part of the runoff hydrograph is subject to treatment. Despite the existing methods for estimating the first flush, a robust quantitative definition is difficult to find. This paper discusses a novel approach, where a new parameter is introduced to analyse the variability in the discharge of pollutants at different times throughout a runoff event and thereby enable the identification of first flush. It was found that due to variability in rainfall, the first flush runoff volume varies from event to event. Therefore, a static estimate of the first flush is not applicable for a runoff event. The Monte Carlo simulation undertaken strengthened the analysis by providing credible limits to the outcomes. Accordingly, an interval estimation was obtained in which the first flush runoff can vary, and it was found that most commonly, the first flush can exist through the initial 30%–50% of the runoff. Therefore, in order to treat the stormwater runoff with minimum risk of discharging high loads of pollutants to the receiving water environment, at least the initial 30% of the runoff should be subject to treatment. This understanding provides a fundamental basis for the design of robust stormwater treatment systems.
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    Physico-chemical properties of sediments governing the bioavailability of heavy metals in urban waterways
    (Elsevier, 2021) Goonetilleke, Ashantha
    Bioavailability is a critical facet of metal toxicity. Although past studies have investigated the individual role of sediment physico-chemical properties in relation to the bioavailability of heavy metals, their collective effects are little-known. Further, limited knowledge exists on the contribution of nutrients to metal bioavailability. In this study, the influence of physico-chemical properties of sediments, including total organic carbon (TOC), total phosphorus (TP), total nitrogen (TN), cation exchange capacity (CEC), specific surface area (SSA), and mineralogical composition to metal bioavailability is reported. The weak-acid extraction method was used to measure Cd, Cr, Cu, Ni, Pb and Zn as the potentially bioavailable fraction in sediments in an urban creek. The results confirmed that Cu has strong selectivity for organic matter (r = 0.814, p < 0.01). Cr bioavailability was influenced by either sediment mineralogy, nutrients, CEC or SSA. Zn, Ni and Pb showed strong affinity to mineral oxides, though their preferred binding positions were with nutrients, particularly organic matter (r = 0.794, 0.809, and 0.753, p < 0.01, respectively). The adsorption of Cd was strongly influenced by the competition with other metals and its bioavailability was weakly influenced by ion exchange (CEC: r = 0.424, p < 0.01). The study results indicate that nitrogen and phosphorus compounds can elevate metal bioavailability due to complexation reactions. Generally, the estuarine area was more favourable for the adsorption of weakly-bound metals. This is concerning as estuaries generate high biogeochemical activity and are economically important.