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    Disentangling increasing compound extremes at regional scale during Indian summer monsoon
    (Springer, 2021-08) Guntu, Ravikumar
    Compound extremes exhibit greater adverse impacts than their univariate counterparts. Studies have reported changes in frequency and the spatial extent of extremes in India; however, investigation of compound extremes is in the infancy state. This study investigates the historical variation of compound dry and hot extremes (CDHE) and compound wet and cold extremes (CWCE) during the Indian summer monsoon period from 1951 to 2019 using monthly data. Results are analyzed for 10 identified homogeneous regions for India. Our results unravelled that CDHE (CWCE) frequency has increased (decreased) by 1–3 events per decade for the recent period (1977–2019) relative to the base period (1951–1976). Overall, the increasing (decreasing) pattern of CDHE (CWCE) is high across North-central India, Western India, North-eastern India and South-eastern coastlines. Our findings help in identification of the parts of the country affected by frequent and widespread CDHE during the recent period, which is alarming. More detailed assessments are required to disentangle the complex physical process of compound extremes to improve risk management options.
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    More than one landslide per road kilometer – surveying and modelling mass movements along the Rishikesh-Joshimath (NH-7) highway, Uttarakhand, India
    (2023-01) Guntu, Ravikumar
    The rapidly expanding Himalayan road network connects rural mountainous regions. However, the fragility of the landscape and poor road construction practices lead to frequent mass movements along-side roads. In this study, we investigate fully or partially road-blocking landslides along the National Highway (NH-) 7 in Uttarakhand, India, between Rishikesh and Joshimath. Based on an inventory of > 300 landslides along the ~250 km long corridor following exceptionally high rainfall in October and September 2022, we identify the main controls on the spatial occurrence of mass-movement events. Our analysis and modelling approach conceptualizes landslides as network-attached spatial point pattern. We evaluate different gridded rainfall products and infer the controls on landslide occurrence using Bayesian analysis of an inhomogeneous Poisson process model. Our results reveal that slope, rainfall amounts, and lithology are the main environmental controls on landslide occurrence. The individual effects of aggregated lithozones is consistent with previous assessments of landslide susceptibilities of rock types in the Himalayas. Our model spatially predicts landslide occurrences and can be adapted for other rainfall scenarios, and thus has potential applications for efficiently allocating efforts for road maintenance. To this end, our results highlight the vulnerability of the Himalayan road network to landslides. Climate change and increasing exposure along this pilgrimage route will likely exacerbate landslide risk along the NH-7 in the future
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    Economic consequences of cascading drought-flood events: evidence from central Europe
    (IOP, 2025-10) Guntu, Ravikumar
    Cascading drought-flood events (CDFEs), also referred to as ‘drought-to-flood transitions’ or ‘drought–flood abrupt alternations,’ in which a flood follows a period of drought, may have different flood generation mechanisms than floods occurring independently from drought, as the drought could affect soil infiltration rates and, consequently, runoff dynamics. With the increasing frequency of extreme weather events driven by climate change, understanding the cascading nature of drought and flood events has become crucial for effective disaster risk management. However, there is a lack of empirical evidence on how these drought-flood interactions work and translate to economic losses. This study addresses this gap by identifying CDFEs and flood-only events (FEs) across Central Europe and linking them to their flood impacts from the modelled Historical Analysis of Natural Hazards in Europe database. CDFEs are associated with significantly higher maximum daily mean streamflow (58.51 m3 s−1 vs 38.20 m3 s−1), deeper mean water depths (1.90 m vs 1.88 m), and greater economic losses (€33.09 million km−2 vs €29.75 million km−2) compared to FEs. These findings underscore the special features of CDFEs and the need to take them into account in flood risk management.
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    Traffic and climate change impacts on water quality 2010
    (IGI Global, 2010) Goonetilleke, Ashantha
    Traffic and climate change impacts on water quality Food and Agriculture Organization of the United Nations Discover About FAO News Multimedia Main topics Statistics Members Publications English العربية Español Français Русский 中文 AGRIS - International System for Agricultural Science and Technology About AGRIS Contribute Acceptable use policy facebook linkedin twitter weibo Close Advanced Search Traffic and climate change impacts on water quality 2010 Mahbub, Parvez | Ayoko, Godwin | Egodawatta, Prasanna | Yigitcanlar, Tan | Goonetilleke, Ashantha AGROVOC Keywords climate change heavy metals traffic water quality Bibliographic information Publisher IGI Global Other Subjects 4011 environmental engineering; Sample testing; Institute for sustainable industries and liveable cities
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    Effects of climate change on the wash-off of volatile organic compounds from urban roads
    (Elsevier, 2011-09) Goonetilleke, Ashantha
    The predicted changes in rainfall characteristics due to climate change could adversely affect stormwater quality in highly urbanised coastal areas throughout the world. This in turn will exert a significant influence on the discharge of pollutants to estuarine and marine waters. Hence, an in-depth analysis of the effects of such changes on the wash-off of volatile organic compounds (VOCs) from urban roads in the Gold Coast region in Australia was undertaken. The rainfall characteristics were simulated using a rainfall simulator. Principal Component Analysis (PCA) and Multicriteria Decision tools such as PROMETHEE and GAIA were employed to understand the VOC wash-off under climate change. It was found that low, low to moderate and high rain events due to climate change will affect the wash-off of toluene, ethylbenzene, meta-xylene, para-xylene and ortho-xylene from urban roads in Gold Coast. Total organic carbon (TOC) was identified as predominant carrier of toluene, meta-xylene and para-xylene in < 1 μm to 150 μm fractions and for ethylbenzene in 150 μm to > 300 μm fractions under such dominant rain events due to climate change. However, ortho-xylene did not show such affinity towards either TOC or TSS (total suspended solids) under the simulated climatic conditions.
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    Application of Resilience concept for enhanced management of water supply systems
    (International Conference on Sustainable Built Environment (SBE), 2013) Goonetilleke, Ashantha
    This paper presents an approach to developing indicators for expressing resilience of a generic water supply system. The system is contextualised as a meta-system consisting of three subsystems to represent the water catchment and reservoir, treatment plant and the distribution system supplying the end-users. The level of final service delivery to end-users is considered as a surrogate measure of systemic resilience. A set of modelled relationships are used to explore relationships between system components when placed under simulated stress. Conceptual system behaviour of specific types of simulated pressure is created for illustration of parameters for indicator development. The approach is based on the hypothesis that an in-depth knowledge of resilience would enable development of decision support system capability which in turn will contribute towards enhanced management of a water supply system. In contrast to conventional water supply system management approaches, a resilience approach facilitates improvement in system efficiency by emphasising awareness of points-of-intervention where system managers can adjust operational control measures across the meta-system (and within subsystems) rather than expansion of the system in entirety in the form of new infrastructure development.
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    Prediction of the wash-off of traffic related semi- and non-volatile organic compounds from urban roads under climate change influenced rainfall characteristics
    (Elsevier, 2012-04) Goonetilleke, Ashantha
    Traffic generated semi- and non-volatile organic compounds (SVOCs and NVOCs) pose a serious threat to human and ecosystem health when washed off into receiving water bodies by stormwater. Climate change influenced rainfall characteristics makes the estimation of these pollutants in stormwater quite complex. The research study discussed in the paper developed a prediction framework for such pollutants under the dynamic influence of climate change on rainfall characteristics. It was established through principal component analysis (PCA) that the intensity and durations of low to moderate rain events induced by climate change mainly affect the wash-off of SVOCs and NVOCs from urban roads. The study outcomes were able to overcome the limitations of stringent laboratory preparation of calibration matrices by extracting uncorrelated underlying factors in the data matrices through systematic application of PCA and factor analysis (FA). Based on the initial findings from PCA and FA, the framework incorporated orthogonal rotatable central composite experimental design to set up calibration matrices and partial least square regression to identify significant variables in predicting the target SVOCs and NVOCs in four particulate fractions ranging from >300 to 1 μm and one dissolved fraction of <1 μm. For the particulate fractions in >300–1 μm range, similar distributions of predicted and observed concentrations of the target compounds from minimum to 75th percentile were achieved. The inter-event coefficient of variations for particulate fractions of >300–1 μm was 5–25%. The limited solubility of the target compounds in stormwater restricted the predictive capacity of the proposed method for the dissolved fraction of <1 μm.
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    An integrated framework for assessing community resilience in disaster management
    (International Institute for Infrastructure Renewal and Reconstruction, 2013) Goonetilleke, Ashantha
    Climate change is predicted to increase the frequency and severity of extreme weather events which pose significant challenges to the ability of government and other relief agencies to plan for, cope with and respond to disasters. Consequently, it is important that communities in climate sensitive and potential disaster prone areas strengthen their resilience to natural disasters in order to expeditiously recover from potential disruptions and damage caused by disasters. Building self reliance and, particularly in the immediate aftermath of a disaster, can facilitate short-term and long-term community recovery. To build stronger and more resilient communities, it is essential to have a better understanding of their current resilience capabilities by assessing areas of strength, risks and vulnerabilities so that their strengths can be enhanced and the risks and vulnerability can be appropriately addressed and mitigated through capacity building programs. While a number of conceptual frameworks currently exist to assess the resilience level of communities to disasters, they have tended to differ on their emphasis, scope and definition of what constitutes community resilience and how community resilience can be most effectively and accurately assessed. These limitations are attributed to the common approach of viewing community resilience through a mono-disciplinary lens. To overcome this, this paper proposes an integrated conceptual framework that takes into account the complex interplay of environmental, social, governance, infrastructure and economic attributes associated with community resilience. The framework can be operationalised using a range of resilience indicators to suit the nature of a disaster and the specific characteristics of a study region.
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    Assessing resilience of water resources systems under the impacts of climate change
    (Queensland University of Technology, 2015) Goonetilleke, Ashantha
    This paper presents an approach to assess the resilience of a water supply system under the impacts of climate change. Changes to climate characteristics such as rainfall, evapotranspiration and temperature can result in changes to the global hydrological cycle and thereby adversely impact on the ability of water supply systems to meet service standards in the future. Changes to the frequency and characteristics of floods and droughts as well as the quality of water provided by groundwater and surface water resources are the other consequences of climate change that will affect water supply system functionality. The extent and significance of these changes underline the necessity for assessing the future functionality of water supply systems under the impacts of climate change. Resilience can be a tool for assessing the ability of a water supply system to meet service standards under the future climate conditions. The study approach is based on defining resilience as the ability of a system to absorb pressure without going into failure state as well as its ability to achieve an acceptable level of function quickly after failure. In order to present this definition in the form of a mathematical function, a surrogate measure of resilience has been proposed in this paper. In addition, a step-by-step approach to estimate resilience of water storage reservoirs is presented. This approach will enable a comprehensive understanding of the functioning of a water storage reservoir under future climate scenarios and can also be a robust tool to predict future challenges faced by water supply systems under the consequence of climate change.
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    Impact of climate change on urban water demand in future decades: an Australian case study
    (Nova, 2015) Goonetilleke, Ashantha
    World's climate is changing and it is predicted by a significant number of scientific studies that changes in climate conditions will escalate in the later part of the century. As a consequence, urban water demand is likely to be affected. Changes in water demand will exert significant pressure on the water authorities to maintain the balance between water demand and supply. Therefore, assessment of climate change impacts on water demand is crucial to ensure water demand is met under changed climate conditions. This chapter discusses the outcomes of a critical review of literature on climate variables in water demand modelling. It also evaluated the impacts of climate change on future water demand in the Blue Mountains region, New South Wales, Australia, as a case study with the climate projections from a global climate model, CSIRO Mk. 3. It was found that temperature and rainfall are the mostly used climate variables in water demand modelling; however, their form (e.g. maximum temperature, total rainfall and number of rain days) and incorporation of other climate variables in modelling need to be investigated to develop a robust water demand model to identify the climate change impact more efficiently. Results of climate change impact assessment on urban water demand demonstrated that future water demand in the Blue Mountains region in Australia would not be significantly impacted by the changed climate conditions. The results presented in this chapter provide important insights which could be useful in conducting a more rigorous climate change impact analysis on urban water demand in other cities and regions.