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Urban flooding poses a significant challenge to the rapidly growing Indian cities. Low-impact development strategies such as green roofs have shown the potential to reduce urban flooding. However, their performance assessment significantly varies across different studies. Therefore, the study's primary objective is to evaluate green roofs in the Indian context. For this evaluation, the green roofs are assessed based on building-level implementation scenarios for a high-density urban area in India for 25%,50%, and 75% application rates and different rainfall intensities (2,3 and 4-h duration and 2,5,10 and 25-year frequencies). Secondly, to probe the variations in the green roof performance across studies, uncertainty contributions to the runoff reduction from different parameters are quantified. The results show that green roofs can reduce up to 62% of flood volume and 24% of runoff. However, they are reasonably effective only beyond 25% application rates. Further, rainfall intensity contributes the most to the uncertainty of runoff reduction from green roofs. This uncertainty assessment implies that localized evaluation of green roofs depending on local rainfall conditions is required for city-wide policy planning. The study has a significant contribution to building confidence in the ability of green roofs to reduce urban floods in the context of developing countries like India. • Green roof performance is assessed through building-level implementation scenarios. • Green roofs show a reduction of up to 62% in flood volume and 24% in runoff. • Green roofs are reasonably effective only at a minimum 25% application rate. • Rainfall intensity contributes the highest to the total performance uncertainties. • Uncertainty quantification can explain performance variations across studies. [ABSTRACT FROM AUTHOR]

The application of multiple-attribute decision-making (MADM) to real life decision problems suggests that avoiding the loss of information through scenario-based approaches and including expert opinions in the decision-making process are two major challenges that require more research efforts. Recently, a wastewater treatment technology selection effort has been made with a ‘scenario-based’ method of MADM. This paper focuses on a novel approach to incorporate expert opinions into the scenario-based decision-making process, as expert opinions play a major role in the selection of treatment technologies. The sets of criteria and the indicators that are used consist of both qualitative and quantitative criteria. The group decision-making (GDM) approach that is implemented for aggregating expert opinions is based on an analytical hierarchy process (AHP), which is the most widely used MADM method. The pairwise comparison matrices (PCMs) for qualitative criteria are formed based on expert opinions, whereas, a novel approach is proposed for generating PCMs for quantitative criteria. It has been determined that the experts largely prefer natural treatment systems because they are more sustainable in any scenario. However, PCMs based on expert opinions suggest that advanced technologies such as the sequencing batch reactor (SBR) can also be appropriate for a given decision scenario. The proposed GDM approach is a rationalized process that will be more appropriate in realistic scenarios where multiple stakeholders with local and regional societal priorities are involved in the selection of treatment technology. [Copyright &y& Elsevier]

Abstract: Many technological alternatives for wastewater treatment are available, ranging from advanced technologies to conventional treatment options. It is difficult to select the most appropriate technology from among a set of available alternatives to treat wastewater at a particular location. Many factors, such as capital costs, operation and maintenance costs and land requirement, are involved in the decision-making process. Sustainability criteria must also be incorporated into the decision-making process such that appropriate technologies are selected for developing economies such as that of India. A scenario-based multiple-attribute decision-making (MADM) methodology has been developed and applied to the selection of wastewater treatment alternative. The four most commonly used wastewater treatment technologies for treatment of municipal wastewater in India are ranked for various scenarios. Six scenarios are developed that capture the regional and local societal priorities of urban, suburban and rural areas and translate them into the mathematical algorithm of the MADM methodology. The articulated scenarios depict the most commonly encountered decision-making situations in addressing technology selection for wastewater treatment in India. A widely used compensatory MADM technique, TOPSIS, has been selected to rank the alternatives. Seven criteria with twelve indicators are formulated to evaluate the alternatives. Different weight matrices are used for each scenario, depending on the priorities of the scenario. This study shows that it is difficult to select the most appropriate wastewater treatment alternative under the “no scenario” condition (equal weights given to each attribute), and the decision-making methodology presented in this paper effectively identifies the most appropriate wastewater treatment alternative for each of the scenarios. [Copyright &y& Elsevier]

Increasing urbanization and rapid depletion of resources have forced authorities to shift from traditional linear system of take-make-use-dispose to circular system of resource conservation. Circular Economy (CE) is a sustainable development approach that works on the waste management strategy of reduce, reuse, recycle, and recover. Considerable work has been performed on CE in various sectors such as in electronic sector, construction sector, automotive sector, etc. However, CE in the water sector is gaining rapid attention, because of imbalance in water resources and the prevailing linear approach. The aim of this study is to review the world-wide growth of CE concept in the water sector from an economic, environmental, social, and technical perspective. 98 publications were selected by systematic literature review and categorized in economic, environmental, social, and technical criteria including a combination of multiple criteria. In this study, the world-wide status of CE implementation in the water sector is assessed and strategies to encourage and enhance CE implementation are proposed. The six BS8001:2017 principles and 6Rs (reduce, reuse, recycle, reclaim, recover, restore) of waste management are critically analyzed for deriving recommendations and successful implementation of CE in water sector. Finally, challenges and opportunities to implement CE in the water sector in India are discussed. Image 1 • Worldwide growth of Circular economy (CE) in the water sector is reviewed. • Confluence of 6Rs and BS8001:2017 principles is needed for CE implementation. • Challenges and opportunities to implement CE strategies in India are discussed. • Framework needs to be developed to monitor CE implementation in water sector. [ABSTRACT FROM AUTHOR]