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Combined sewer overflows (CSOs) are of major concern for urban water environment restoration that draws worldwide attention. The enaction of related policies, regulations, guidelines and criteria forms a crucial foundation for CSO control and management. Some developed countries, such as the US and European countries, are leading the CSO control and management worldwide and have developed a relatively completed legislative framework. Despite great efforts made worldwide, the existing combined sewer systems and severe illicit sanitary sewer connections to storm sewers still result in urban wet-weather flows (UWWF) pollution which is similar to or even more detrimental than CSOs, deteriorating receiving water bodies, particularly in developing countries. This article aims to review the history and evolution of CSO-related policies, regulations, permits, criteria, technical guidances and measures in typical developed countries to guide the UWWF pollution control and management in latecomers. It was found that the US has formed a complete system from national policies to states' control practices and proceeded to a green development stage. European countries have transitioned CSO control targets toward meeting water quality standards. In comparison, Japan and South Korea attach importance to end-of-pipe treatment and sewer management. On this basis, recommendations were proposed for long-term UWWF control and management in China. This is also expected to guide the enactment of related policies and regulations in less developed countries facing serious UWWF pollution. [ABSTRACT FROM AUTHOR]

A sediment perimeter barrier is a common practice along the perimeter of construction sites to prevent sediment from being washed over all the way to the nearby storm drains or directly into water bodies. It is important to apply barriers during construction since the grading and demolition do not allow the application of other ground surface protection, such as erosion control blankets. To better understand the mechanism, this paper conducted a comprehensive review of the effectiveness of structural sediment perimeter barriers (SPBs) in preventing sediment pollution. The study systematically analyzed the experimental design and results of previous research studies, including their strengths and limitations. The findings suggest that while SPBs have shown promise in reducing sediment pollution, their effectiveness varies depending on factors such as experimental design, installation, and sampling approach. Worse still, the criteria to evaluate the SPBs also differed across different studies. From the reviewed studies, we identified that there is a need to develop a unified test standard, especially on evaluation criteria and water sampling protocol. Additionally, there is a need for more studies to be conducted in various geographical and climatic conditions to assess the performance of SPBs. Although some models (WEPP and VFSMOD) have been proven to be effective in predicting the effectiveness of non-structural SPBs (vegetative filter strips), exploring the feasibility of these existing models in simulating structural SPBs to be subjected to sedimentladen water is recommended. Other software or methods used in the area of computational fluid dynamics, such as HYDRUS-3D, ANASYS, EDEM, and finite volume methods (FVM), could also be introduced in this field. [ABSTRACT FROM AUTHOR]

A changing climate and growing coastal populations exacerbate the outcomes of environmental hazards. Large‐scale flooding and acute disasters have been extensively studied through historic and current data. Chronic coastal flooding is less well understood and poses a substantial threat to future coastal populations. This paper presents a novel technique to record chronic coastal flooding using inexpensive accelerometers. This technique was tested in Key West, FL, USA using storm drains to deploy HOBO pendant G data loggers. The accuracy and feasibility of the method was tested through four deployments performed by a team of local stakeholders and researchers between July 2019–November 2021 resulting in 22 sensors successfully recording data, with 15 of these sensors recording flooding. Sensors captured an average of 13.58 inundation events, an average of 12.07% of the deployment time. Measured flooding events coincided with local National Oceanic and Atmospheric Administration (NOAA) water level measurements of high tides. Multiple efforts to predict coastal flooding were compared. Sensors recorded flooding even when NOAA water levels did not exceed the elevation or flooding thresholds set by the National Weather Service (NWS), indicating that NOAA water levels alone were not sufficient in predicting flooding. Access to an effective and inexpensive sensor, such as the one tested here, for measuring flood events can increase opportunities to measure chronic flood hazards and assess local vulnerabilities with stakeholder participation. The ease of use and successful recording of loggers can give communities an increased capacity to make data‐informed decisions surrounding sea level rise adaptation. Plain Language Summary: Floods occurring outside of storm events are increasing in number due to low‐lying coastal communities' exposure to rising sea levels. The extent and impacts of localized and recurrent flooding events are under‐studied compared to extreme storm events. Damaging floods can occur during a high tide or a rain event, and with these chronic floods increasing in frequency, the cumulative impacts caused by sequential events need to be better understood. Therefore, this paper presents a deployment method and results of low‐cost sensors that can capture flood occurrences and durations in targeted areas using storm drains as a deployment location. A team of researchers and local government employees successfully deployed these sensors between July 2019–November 2021. Flooding was recorded on 15 of the 22 deployed sensors recording an average of 13.58 inundation events causing the storm drains to be inundated on average 12.07% of the deployment time. Key Points: The accelerometers were easy to deploy by researchers and stakeholders and accurately captured flooding in locations of interestInundation was variable across the island of Key West and was not successfully predicted by the NOAA water level alonePatterns to inundation events were not found, water level and timing of inundation varied between and within sites [ABSTRACT FROM AUTHOR]

Ensemble analysis is proven to provide advantages in climate change impact assessment based on outputs from climate models. Ensembled series are shown to outperform single-model assessments through increased consistency and stability. This study aims to test the improvement of precipitation estimates through the use of ensemble analysis for south and southwestern Turkey which is known to have complex climatic features due to varying topography and interacting climate forcings. The analysis covers an evaluation of the performance of eight regional climate models (RCMs) from the EUR-11 domain available from the CORDEX database. The historical outputs are evaluated for their representativeness of the current climate of the Mediterranean region and its surroundings in Turkey through a comparison with long-term monthly precipitation time series obtained from ground-based precipitation observations by the use of statistical performance indicators and Taylor diagrams. This is followed by a comparative evaluation of three ensemble methodologies, simple average of the models, multiple linear regression for superensemble, and artificial neural networks (ANN). The analysis results show that the overall performance of ensembled time series is better compared to individual RCMs. ANN generally provided the best performance when all RCMs are used as inputs. Improvement in the performance of ensembling due to the use of nonlinear models is further confirmed by fuzzy inference systems (FIS). Both ANN and FIS generated monthly precipitation time series with higher correlations with those of observations. However, extreme events are poorly represented in the ensembled time series, and this may result in inefficiency in the design of various water structures such as spillways and storm water drainage systems that are based on high return period events. [ABSTRACT FROM AUTHOR]

Stormwater drainage networks are designed to reduce the risk of rainwater damage to the served area. The purpose of optimizing a stormwater drainage system is to reduce overall construction costs and to meet hydraulic design requirements. Currently, designs that rely on software or manual calculations are limited by the available time and the designer's capabilities. In fact, manual optimization for large networks consumes a lot of time and effort, and there is no guarantee that the optimal design is reached, also it is subject to human errors. In recent years, several researchers have focused on creating optimization design algorithms specifically for sewer and storm networks, such as genetic algorithm (GA), linear programming (LP), heuristic programming (HP),...etc. However, these studies were limited to covering one or two design parameters and constraints. Additionally, in some studies, the hydraulic performance of the designed network was not treated in a proper way, especially the water surface profile effects. So, the main objective of the study is to develop an effective hydraulic-based optimization algorithm (HBOA) that can dynamically get the optimal design with minimum total cost for a given storm network layout and meet all hydraulic requirements. To achieve this, a MATLAB code is created and coupled with SewerGEMS software that automatically simulates all expected optimization scenarios based on network hydraulic performance. The HBOA is validated economically and hydraulically using two benchmark examples from the literature. According to the economic validation, the total network cost generated by HBOA was the lowest when compared to the optimization methods found in the literature. During the hydraulic evaluation, it was observed that the optimization algorithm (GA-HP) used in the literature for the benchmark examples does not meet the hydraulic requirements where the networks are flooded, whereas HBOA meets the hydraulic requirements with minimal overall network cost. Also, the HBOA is applied to four real stormwater drainage networks that were already designed, constructed, and optimized manually. The four redesigned real cases using HBOA revealed a cost reduction of about 15% compared to the original designs, while consuming a few hours for the design and optimization processes. Finally, the developed HBOA is a robust, time-efficient, and cost-effective optimization and hydraulic design tool which could be used in the design of stormwater drainage networks with different design constraints with minimal human interference. [ABSTRACT FROM AUTHOR]

The storm sewer geyser is a process where an air–water mixture violently erupts from a manhole. Despite the low hydrostatic pressure, violent eruptions can achieve a height of tens of meters above the ground. This current study experimentally investigates large-scale violent geysers using a large air pocket inserted from a pressurized air tank. The total length of the pipe system is approximately 88 m with a 0.1572 m diameter pipe. This large-scale experiment facilitates the investigation of spontaneous geyser eruptions. This study identifies the role of air–water volume ratio and coefficient of pressure (ratio of absolute initial static pressure to initial dynamic pressure) on the geyser intensity using eruption images and pressure plots. A total of 116 cases are tested, in which the volume ratio is parametrically increased from 0 to 1.1 under various operating conditions. A geyser score is defined to quantify the geyser eruption nature based on visual observations. The key findings are as follows: first, a sharp transition in geyser intensity is observed at the critical volume ratio of 0.5, and pre-transition and post-transition intensity exhibit a linear relationship with the volume ratio; and second, the critical volume ratio linearly varies with the coefficient of pressure. [ABSTRACT FROM AUTHOR]

Modifications to the landscape for urban expansion directly impact the natural hydrological dynamics in Urban Hydrographic Micro-basins (UHMs). This study aims to develop the Urban Flood Susceptibility Index (UFSI) from indicators pertinent to different spheres, considering both infiltration and surface runoff of rainwater, and apply it in UHMs of a municipality in the Midwest Region of Brazil. Historical records of urban floods available in information media are used to validate the UFSI. The methodology adopted involves the Analytical Hierarchical Process linked to the Geographic Information System. UFSI is composed of the following indicators: average slope (Sa), coefficient of compactness (Kc), drainage density (Dd), demographic density (Ddem), degree of surface permeability (DSP), susceptibility to production of sediment (SPS), daily precipitation (Pd), degree of canalization of watercourses (DCW), condition of storm drains (CSD), and rainwater retention devices (RRD). Therefore, USFI simultaneously includes morphometric, environmental, land use and occupation, and urban infrastructure indicators. Pd (0.16 for both dimensions) and DSP (0.15 for surface runoff and 0.26 for infiltration) indicators are the most significant for urban flood susceptibility in both analysed dimensions. Sa (0.15) and DCW (0.14) are relevant in relation to surface runoff, while RRD (0.13) and SPS (0.09) regarding to infiltration. UFSI and historical records of each UHM obtained strong correlation (r > 0.80), evidencing reliability and validation of the index. The UFSI can assist in the formulation of guidelines for land use and occupation and to indicate UHMs that require attention from the public authority for sustainable socioeconomic development. [ABSTRACT FROM AUTHOR]

Urban areas produce large amounts of stormwater runoff due to vast areas of impervious surfaces. Stormwater inlets, or catch basins, are commonly used for collecting and directing stormwater runoff away from streets and sidewalks. The conveyances used to direct flow to surface waters may be part of a municipal separate storm sewer systems (MS4s). Typically, MS4s redirect runoff without providing a means for removing harmful pollutants. These pollutants are then often discharged directly into local lakes, rivers, and streams, potentially harming native aquatic ecosystems. Post-construction stormwater practices are commonly used to treat runoff from urban areas by reducing the total runoff volume, lowering peak flow rates, and/or removing harmful pollutants from runoff. However, some post construction stormwater practices require large footprints, construction, and maintenance. Catch basin inserts (CBIs) are one type of post-construction best management practice that are installed within existing catch basins and require no additional land use while still providing a means for removing pollutants from stormwater runoff before entering the MS4. However, limited data is available to demonstrate the expected performance of various CBIs to ensure that these practices meet the pollutant removal standards set forth by the US Environmental Protection Agency (USEPA). The objective of this study was to evaluate the sediment removal capabilities of eight different proprietary CBI products for potential use as a post-construction stormwater practice for Department of Transportation projects. Results indicate that only two basket-type CBIs met the 80% sediment retention benchmark established for the study. While not surpassing the benchmark, three bag-type CBIs did achieve more than 70% sediment retention. The remaining three CBIs (one basket-type, one bag-type, and one cartridge type) fell notably short of the performance benchmark. [ABSTRACT FROM AUTHOR]

Water quality credit trading has been advanced as a cost‐effective means of achieving regulatory compliance. However, the volume of trading activity in operational programs is typically less than estimated by empirical analysis. The compliance behavior of Virginia Municipal Separate Storm Sewer Systems (MS4s) is studied in response to the Chesapeake Bay total maximum daily load (TMDL) to understand the circumstances in which trading is adopted, the extent to which trading is adopted, and the factors contributing to trading's use or nonuse. Results indicate that MS4s generally prefer to install their own pollutant control measures rather than trade. Many MS4s, however, rely on trade as a backup compliance option. MS4s favor bay compliance options that help meet other local management objectives (erosion control, infrastructure protection, and reductions toward local water quality objectives) and provide long term pollutant control benefits. Low cost term credits do not provide such benefits. For perpetual credits, MS4s use a variety of strategies to substantially reduce the cost differences between trade and nontrade compliance options. [ABSTRACT FROM AUTHOR]

Flash floods are common in the town of Kokrajhar in north-eastern Indian state of Assam. Many areas in the town of Kokrajhar are submerged in water almost every year due to floods during rainy season. These floods cause heavy damage to roads, agricultural production and halt the progress of major infrastructural development projects. Hence, prevention of floods has become an important concern in the town of Kokrajhar. This study investigated the causes of floods and offered a solution for their elimination. The investigation showed that inadequate and inefficient network of storm drains was the reason for the flash floods. A new drainage network for the town of Kokrajhar has resulted from studying the shortcomings of the existing network of storm drains. The new network is designed in accordance with the recommendations stated in the “Manual on storm water drainage systems” prepared by the Central Public Health and Environmental Engineering Organization in 2019. [ABSTRACT FROM AUTHOR]

The violent nature of storm sewer geysers has been puzzling researchers worldwide for a very long time. This paper investigates the geyser simulation methodology using a small-scale set-up, where important flow structures such as slugs, eruption patterns, and pressure oscillations are compared with experimental results to test the fidelity of the numerical modelling. In this exercise, a geyser-like process is produced using a continuous insertion of air in the horizontal pipe. The established methodology is used to simulate the hypothesized scenario of a finite trapped air pocket in the relatively longer pipe system. A geyser produced from a finitely trapped air pocket shows a different eruption mechanism compared to those found in previous studies. First, no slug is observed in the horizontal pipe, resulting in continuous air release. Second, the interface continuously atomizes in the vertical pipe, creating a churn-slug flow that produces a large number of small eruptions. [ABSTRACT FROM AUTHOR]

Urban flooding is a problem faced by most countries because of climate change. Without storm drainage systems, negative impacts may occur, such as traffic problems and increasing groundwater levels, especially in lowlands. The implementation of storm drainage networks and their fittings in poor countries is affecting their economic development. Therefore, improving the efficiency of the storm drainage network is an important issue that should be considered. This paper aims to study the most appropriate position or arrangements of grate inlets to upgrade drainage efficiency at less cost. Different arrangements of grates were studied and their efficiency was determined. A comparison between the total grate's efficiency was conducted and the best arrangement was selected. Additionally, a dimensional analysis equation was developed to determine the total efficiency of the system. Finally, the FLOW-3D program was used to simulate the laboratory results using different discharges and numbers of inlets. The error of calculation ranged between 5% and 8%. Therefore, the results indicated that this program is a powerful tool for predicting the discharge efficiency and velocity direction for large discharges. A comparison was made between this study and previous studies. The results indicated that the same trend existed. A new equation was developed to correlate discharge efficiency (E) with relative total discharge Q and number of inlets. The equation can be used by planning engineers to conduct initial planning of storm drainage layout systems and achieve cost saving. [ABSTRACT FROM AUTHOR]

Climate change and urbanization are resulting in increased runoff for stormwater sewers to handle. This work uses hydraulic modeling and typical US prices to quantify the cost increase due to the larger pumps and pipes that will be needed for various amounts of discharge increase. Analysis was performed on a single sewer pipe and pump but also on a hypothetical system of varying sizes, incorporating cost for pipes pumps, and electricity usage. It was found that gravity-flow systems will cost up to nine times more than the current design amount. Cost increases can be estimated by a linear function with slope ranging from 0.025 to 0.019. The cost can increase by a factor of 0.24 for a 30-pipe system at a slope of 0.0001 and as little as 0.03 for a single pipe system at a slope of 0.0019. For a force main, the cost increase ratio is a function of the discharge ratio to the 0.5 power. For corrugated pipes, the cost ratio varied from 31% to 39% from that of concrete pipe and from 20% to 22% for a PVC pipe, making additional funds necessary. This has implications for total maximum daily load (TMDL) because more stormwater, especially of pollutant concentration greater than the TMDL concentration, will be entering surface water bodies subject to TMDL regulations. [ABSTRACT FROM AUTHOR]

Hong Kong (HK), one of the world's most densely populated metropolises, is home to over 200 rivers and streams extending about 2500 km in length. During the 1970s–1990s, most of these rivers were converted into artificial canals, to which the local society pays little attention. Since the 2010s, the HK government has initiated river revitalization to enhance the social-environmental roles of rivers. This study employed a mixed research method, including literature and policy analysis, expert interviews, field visits, and a public survey, to identify key challenges in HK's Integrated River Basin Management (IRBM). The findings highlighted the lack of IRBM's institutional arrangements in HK, characterized by a fragmented 'one river, two systems' approach without both coordination and collaboration. The Water Supplies Department (WSD) impounds upland streams as reservoirs for securing the local water supply, while the Drainage Service Department (DSD) manages heavily channelized, culverted downstream serving as storm drains with diminished ecological functionality. One significant barrier to the implementation of IRBM in HK was the limited public participation, although our survey revealed a high level of public willingness to participate in river management. Presently, river revitalization efforts have achieved limited success, with ecological measures appearing mostly "cosmetic" and the conservation of freshwater biodiversity neglected. This further underscored the pressing need for the embracement of IRBM in HK to safeguard basin-wide freshwater ecosystems. Our survey also indicated low public awareness of river revitalization initiatives and widespread dissatisfaction with their outcomes. In conclusion, we proposed the development of IRBM in HK by instituting river basin coordination, prioritizing river ecosystem restoration in revitalization projects, and involving the public through tailored strategies. [ABSTRACT FROM AUTHOR]

The burgeoning significance of urban floods in the context of evolving climate dynamics and shifting rainfall patterns underscores the exigency for comprehensive investigation and mitigation strategies. The study employs a multi-criteria assessment (MCE) approach and the analytical hierarchy process (AHP) to evaluate flood-vulnerable zones, wards, and sub-category-wise flood locations in Greater Mumbai. The AHP technique is used to evaluate flood-vulnerable impacting parameters such as rainfall (29.42%), slope (20.96%), land use/land cover (17.52%), vicinity to sewers and storm-water drainage (13.99%), vicinity to natural drainage (8.97%), vegetation (5.58%), and soil (3.56%). The study area is classified under different vulnerable categories as severe vulnerable (46.72%), high to very high (18.74%), and slight to moderate (34.54%). Researchers analysed 234 waterlogged locations, revealing that 85.46% (200 locations) were in the severe to very high vulnerability category, and only 14.52% (34 locations) were in the other three categories. Flood locations are more affected by slope (under the categories of < 5 m and 5.01–10 m), built-up land, sewers and storm water drainage (< 125 m), natural drainage (< 250 m), rainfall (< 2000 to 2200 mm), lowest dense vegetation, and coastal alluvium in soils. These model-based flood vulnerability maps are crucial for planning flood conservation and mitigation measures. [ABSTRACT FROM AUTHOR]

The effect of climate change in the world has directly contributed to the increase in the frequency of natural phenomena, including floods. Algeria has suffered from this phenomenon through human and material damage caused by this risk. The objective of this work is to analyze the flood frequency and the number of deaths in Algeria for the period 1969-2022. In this study, 191 events were counted, and 2098 deaths were recorded. The analysis results of the numbers of deaths showed that the period from 1969 to 2009 was characterized by the presence of devastating floods that left large numbers of victims, while during the period 2010 to 2022, it was characterized by the presence of fewer victims but with a large number of floods; the highest number was recorded in 2015, with 14 floods. The absence of storm drains sometimes and its inability to evacuate stormwater, urban expansion and construction at the edges of wadis (major bed) mainly contribute to increasing the risk of flooding. For the period 2010-2022, the most significant number of deaths and flood frequency were recorded in August, September and October, which could be explained by the high temperatures during the summer, which increase the impermeability of the soil and thus increase the risk of floods. The distribution of the number of deaths and the flood frequency by province during this period showed that Djelfa, M'sila, Tamanrasset, Tiaret, Batna, Oran and Medea were most vulnerable to flooding. This work can assist local and national managers in obtaining an overview of the distribution of floods in Algeria and making decisions to mitigate the risk of this phenomenon. [ABSTRACT FROM AUTHOR]

Short‐term increases in stream temperature in response to storm events have frequently been observed in urban areas, highlighting the need for improved understanding of the factors influencing urban stream temperature. Urban land cover complexity and infrastructure designed for rapid water routing to the sewer system create a direct link between storm events and water release processes, influencing urban stream temperature responses. This study aims to identify predictors of diverse stream temperature response patterns to summer storms. We analysed 403 storm events from six urban and semi‐urban catchments along the US East Coast using dynamic time warping to identify archetype patterns of stream temperature responses. We further disentangled observed stream temperature increase patterns to reveal the drivers associated with 'heat pulses', which are characterized by a rapid but high‐magnitude temperature increase followed by a sharp temperature drop at the start of the hydrograph increase. Our results show that stream temperature patterns were event‐specific and linked to pre‐event conditions and rainfall–runoff characteristics, with the shape of the hydrograph and rainfall–runoff response identified as the most important determinators of the observed temperature response patterns. Ponded surface waters and storm drains, as well as cooler water from the shallow subsurface, were identified as potential sources contributing to temperature patterns. These findings have important implications for understanding urban hydrology and the contributions of different source zones in urban catchments. Specifically, our results suggest that stream temperature may serve as a cost‐effective tracer providing information about urban water sources and pathways, thus aiding in the understanding of complex urban hydrology. [ABSTRACT FROM AUTHOR]

This research presents a novel methodology to determine runoff water retention volumes that allow the design of storage tanks for storm sewer overflows. It is based on the use of the Stormwater Management Model (SWMM) to generate hydrographs and runoff pollutographs of a fictional urban basin. Three pollutants (TS, BOD5 and TN) are simulated for a given set of rains and the values taken by a proposed set of characterization variables for the pollutographs obtained are analysed. Correlation and determination coefficients that exist between the different variables are analysed while also performing a multivariate characterization using PCA and cluster analysis. In the case study presented, using IDF curves of the studied city, a probability of occurrence (Tr) is assigned to the values taken by the proposed characterization variables. To assess the impact and identify the most unfavourable pollutographs within the set of selected rains, impact evaluation variables (IEV's) are established, based on the proposed characterization variables and by simulating the discharge to a receiving water body (river with initial concentration and constant flow). Finally, a storm sewer overflow is simulated, deriving a maximum flow for purification, and dimensioning retention tanks for different fractions of the total volume of runoff to control the maximum values of a specific IEV impact evaluation variable. Taking a design return period Trssd ≥ 10 years, the results obtained in the study case were 146.50 m3/ha imp for a 100% retention of the total runoff volume and 117.20 m3/ha imp for an 80% retention. [ABSTRACT FROM AUTHOR]

One of the important ways to prevent permanent environmental pollution is to constantly monitor its quality, which can be performed in several ways. The present bioindication study analyzed the level of diversity and abundance of biofilm microorganism communities, which illustrate the state of the studied aquatic environment, enabling to determine its quality. The impact of stormwater discharge on the receiver at particular points was evaluated on the basis of the reaction of selected microorganisms or their groups to the substances appearing in the watercourse. The study of indicator organisms gives information about the waters of a given body of water without expensive hydrochemical tests and without causing a burden on the environment during the production as well as disposal of reagents that are consumed in many classical physicochemical analyses. On the basis of selected algal species, the Shannon index and McArthur index were calculated, and the effect of storm sewer discharge on the communities of indicator organisms was determined. The best visible impact of storm sewer discharge was seen on the basis of the entire study cycle in relation to the median of the McArthur index. [ABSTRACT FROM AUTHOR]

In cold-climate regions, road salt is used as a deicer for winter road maintenance. The applied road salt melts ice and snow on roads and can be washed off through storm sewer systems into nearby urban streams, harming the freshwater ecosystem. Therefore, aiming to develop a precise and accurate model to determine future chloride concentration in the Credit River in Ontario, Canada, the present work makes use of a "Graph Neural Network"–"Sample and Aggregate" (GNN-SAGE). The proposed GNN-SAGE is compared to other models, including a Deep Neural Network-based transformer (DNN-Transformer) and a benchmarking persistence model for a 6 h forecasting horizon. The proposed GNN-SAGE surpassed both the benchmarking persistence model and the DNN-Transformer model, achieving RMSE and R2 values of 51.16 ppb and 0.88, respectively. Additionally, a SHAP analysis provides insight into the variables that influence the model's forecasting, showing the impact of the spatiotemporal neighboring data from the network and the seasonality variables on the model's result. The GNN-SAGE model shows potential for use in the real-time forecasting of water quality in urban streams, aiding in the development of regulatory policies to protect vulnerable freshwater ecosystems in urban areas. [ABSTRACT FROM AUTHOR]

The use of dual-drainage models has increased in recent decades, mostly because of advances in mathematical methods and geographic information system tools. This type of modelling provides precise diagnoses and can be applied to evaluate stormwater infrastructure and diverse drainage alternatives. Minor and major drainage relations in the Dona Eugênia watershed, Brazil, were analysed in this study. Three alternatives simulated the quasi-two-dimensional hydrodynamic model Modcel. The first alternative considered only the terrain surface layer, representing the current situation. In the second alternative, a layer containing a designed storm sewer was introduced. Considering the previous alternatives as a way to diagnose the main minor and major deficiencies, a third alternative was formulated considering previous projects to solve floods in the watershed, incorporating them in the second alternative with functional minor drainage. The results identified the locations of minor drainage gaps, thus helping to direct efforts to the most critical regions, optimise operations and minimise maintenance costs. The results could also be used to evaluate the effects of storm sewer network discharges in major drainage systems, leading to better design of the drainage infrastructure. The major drainage itself can be optimised, once its responsibility in flooding is identified. [ABSTRACT FROM AUTHOR]

Urban coastal flooding is a global humanitarian and socioeconomic hazard. Rising sea levels will increase the likelihood of hydrologic events interacting with high marine water levels. These compound events may, in turn, nonlinearly interact with urban infrastructure, potentially resulting in more extreme coastal flooding events. Here, an integrated Delft3D-FM based numerical modeling framework is used to concomitantly resolve multi-source flood processes (i.e., high marine water levels, precipitation) and infrastructure (e.g., seawalls, storm drains). Hydrodynamic model results are validated with embayment pressure sensor data and photographic observations from historical events. The impact of tide and precipitation phasing are examined. Multiple storm drain characterizations are presented and evaluated. Results show seawall and storm drain infrastructure is fundamental to accurately resolving spatial and temporal flood dynamics. Importantly, coastal management strategies such as raising seawall elevations to mitigate tidal flooding may exacerbate precipitation-based flooding in low-lying urban regions. [ABSTRACT FROM AUTHOR]

The article discusses the evolution of flood risk research and the increasing recognition of the importance of studying different types of flooding, including urban flooding. Urban flood risk presents unique challenges due to rapidly changing physical and social environments, complex interactions between the natural and built environment, and limited management options. The article highlights several research contributions in the field of urban flood risk management, including studies on long-term flood exposure in Bangkok, assessing future urban flood hazards in Seoul, flash flooding events in hilly cities, post-flood photograph analysis, and maximizing the use of large datasets for flood resilience. The article also acknowledges the importance of diverse perspectives in flood risk research and encourages individuals to become peer reviewers for the journal. [Extracted from the article]

Urban flooding is the submergence of an area by a large amount of water that comes from sudden excessive rainfall. As a result, it overwhelms the capability of the drainage system, such as storm sewers. Surat city is located on India's west coast at the mouth of the Tapi River. Surat city has faced many floods for a long time. The main aim of the study is to simulate the existing stormwater drainage system and to identify any overflowing manholes in Surat City (West Zone) by employing the Storm Water Management Model (SWMM). SWMM is an effective tool for simulating urban floods. In the present study, rainfall data for 2018, 2019 and 2020 and stormwater network data were used to evaluate the present stormwater drainage network. The above data are then imported into SWMM to display the inversion level and drainage network details. The flow direction has been assessed from these inverted-level drain network characteristics to produce a descriptive view of the study area. From the above analysis, it is found that some parts of the western zone are mostly affected by flooding. These flooding conditions can be improved by increasing the dimensions of the conduit pipes of the respective drainage system. Recommendations and suggestive measures are provided to improve the resilience of Surat city against floods. [ABSTRACT FROM AUTHOR]

A vulnerability assessment system for rainwater pipe networks, comprising 13 indexes, was developed to facilitate the rational allocation and timely updating of urban storm drainage systems. An enhanced Borda combination evaluation method, which considers both the optimal and worst solutions, was proposed, accompanied by the operation procedure and numerical calculation method. Five stormwater systems in Central China were selected as case studies, and their vulnerability was evaluated and compared using five distinct evaluation methods: the entropy weight method, the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS), the efficacy coefficient method, the fuzzy comprehensive evaluation method, and the improved fuzzy Borda combination evaluation method. The results demonstrated that the correlation coefficients between the fuzzy Borda combination evaluation method and the four individual evaluation methods were equal to or greater than 0.88, indicating strong agreement. Additionally, the compatibility of the combination evaluation method was found to be 0.96. This study holds both theoretical significance and practical value for preventing urban waterlogging and contributes to the development of more resilient urban storm drainage systems. [ABSTRACT FROM AUTHOR]

Algiers city frequently experiences significant flooding during rainy weather due to the overflow of its storm sewer network (SSN). Through modeling, simulation, and field studies, vulnerable points of the network have been identified. These points are classified based on a combined assessment of hazard and vulnerability. Hazard is estimated using the Analytical Hierarchical Process (AHP) method, which considers the return period, overflowing height, slope, elevation, and waterproofing. On the other hand, vulnerability is determined by population density. Risk is determined by multiplying hazard and vulnerability. Additionally, a classification based on the FMECA method's criticality index has been performed to complement the approach. The concordance between the two methods is evaluated using Lin's concordance correlation coefficient (CCC), showing strong agreement. The sensitivity analysis conducted on the models highlights their reliability and robustness, making the obtained results trustworthy and useful for network managers. This analysis aids in effective flood management by allocating resources and interventions to the most vulnerable areas of Algiers city. [ABSTRACT FROM AUTHOR]

Damage or deterioration of water distribution or storm water drain pipeline systems create a problem of leakage, which has the potential to erode its surrounding soil. This erosion, if not detected in time, can form a large cavity in the ground and consequently results in catastrophic failure. This paper presents a detailed review of soil erosion due to damaged buried pipe using experimental and numerical evidence available in the literature. Herein, erosion is explained using two different flow possibilities, namely, infiltration and exfiltration. A comprehensive discussion on the method of investigation and the erosion mechanism, along with the governing parameters used in the investigation and their challenges, are presented. This review paper also discusses two other issues, that is, the rate of erosion and the volume of cavity formed due to erosion. Both the issues seem to be governed by the hydraulic gradient in the soil, the size of the defect in the pipe and the size of soil particles surrounding the defect. Important empirical and analytical methods which are used to predict the size of the cavity as well as the leakage rate and pressure drop, are also discussed. The location and size of the cavity seems to be highly dependent on the groundwater level. [ABSTRACT FROM AUTHOR]

Physical modeling of precipitation at fine (sub-kilometer) spatial scales is computationally very expensive. This study develops a highly efficient framework for this task by coupling deep learning (DL) and physical modeling. This framework is developed and tested using regional climate simulations performed over a domain covering Montreal and adjoining regions, for the summers of 2015–2020, at 2.5 km and 250 m resolutions. The DL framework uses a recurrent approach and considers atmospheric physical processes, such as advection, to generate high-resolution information from low-resolution data, which enables it to recreate fine details and produce temporally consistent fields. The DL framework generates realistic high-resolution precipitation estimates, including intense short-duration precipitation events, which allows it to be applied in engineering problems, such as evaluating the climate resiliency of urban storm drainage systems. The results portray the value of the proposed DL framework, which can be extended to other resolutions, periods, and regions. [ABSTRACT FROM AUTHOR]

Storm sewer systems may experience storm geysers, raising concerns about public safety. A thorough understanding of the influential factors of the geysers is essential yet insufficiently investigated in the literature. A transient three-dimensional (3D) computational fluid dynamics model incorporating the volume of fluid method is used to investigate the geyser formation mechanism and hydrodynamics. An air pocket in a pressurized pipe travels with water past a vertical shaft, producing an air-releasing geyser and, subsequently, a rapid-filling geyser. If the air pocket in the pipe is too small or if it moves too quickly, a hybrid geyser might be set off when the air-releasing and rapid-filling geysers overlap. A hybrid geyser has unique properties since it combines an air-releasing geyser and a rapid-filling geyser. The presence of hybrid geysers lowers the height of air-releasing and rapid-filling geysers. Equations are proposed for predicting the heights of the geysers with errors of about 15%. The height of the air-releasing geyser increases with the water level in the shaft. As the pressure difference between the two ends of the pipe reduces, the height of the rapid-filling geyser increases. The vertical shaft diameter has little influence on rapid-filling geysers, while a small diameter often results in high air-releasing geysers. The effect on the height of both kinds of geysers is negligible when the air pocket volume is large enough. The findings can be used for designing storm geyser mitigation measures. [ABSTRACT FROM AUTHOR]

Tide gauge water levels are commonly used as a proxy for flood incidence on land. These proxies are useful for projecting how sea‐level rise (SLR) will increase the frequency of coastal flooding. However, tide gauges do not account for land‐based sources of coastal flooding and therefore flood thresholds and the proxies derived from them likely underestimate the current and future frequency of coastal flooding. Here we present a new sensor framework for measuring the incidence of coastal floods that captures both subterranean and land‐based contributions to flooding. The low‐cost, open‐source sensor framework consists of a storm drain water level sensor, roadway camera, and wireless gateway that transmit data in real‐time. During 5 months of deployment in the Town of Beaufort, North Carolina, 24 flood events were recorded. Twenty‐five percent of those events were driven by land‐based sources—rainfall, combined with moderate high tides and reduced capacity in storm drains. Consequently, we find that flood frequency is higher than that suggested by proxies that rely exclusively on tide gauge water levels for determining flood incidence. This finding likely extends to other locations where stormwater networks are at a reduced drainage capacity due to SLR. Our results highlight the benefits of instrumenting stormwater networks directly to capture multiple drivers of coastal flooding. More accurate estimates of the frequency and drivers of floods in low‐lying coastal communities can enable the development of more effective long‐term adaptation strategies. Key Points: We present a new low‐cost, open‐source sensor framework that measures coastal flooding from multiple sourcesFor a 5 month deployment, 25% of floods were driven by land‐based sources, contributions not present in tide gauge water levelsMeasures of flood frequency that rely only on tide gauges are likely underestimates where stormwater networks are routinely impaired [ABSTRACT FROM AUTHOR]

In the UK, decision makers use hydraulic model outputs to inform funding, connection consent, adoption of new drainage networks and planning application decisions. Current practice requires the application of design storms to calculate sewer catchment performance metrics such as flood volume, discharge rate and flood count. With flooding incidents occurring more frequently than their designs specify, hydraulic modelling outputs required by practice are questionable. The main focus of this paper is the peakedness factor (ratio of maximum to average rainfall intensity) of design storms, adjudging that this is a key contributor to model bias. Hydraulic models of two UK sewer catchments were simulated under historical storms, design storms and design storms with modified peakedness to test bias in modelling outputs and the effectiveness of peakedness modification in reducing bias. Sustainable drainage systems (SuDS) were implemented at catchment scale and the betterment achieved in the modelling outputs was tested. The proposed design storm modification reduced the bias that occurs when driving hydraulic models using design storms in comparison with historical storms. It is concluded that SuDS benefits are underestimated when using design rainfall because the synthetic rainfall shape prevents infiltration. Thus, SuDS interventions cannot accurately be evaluated by design storms, modified or otherwise. [ABSTRACT FROM AUTHOR]

Risk-based renewal planning is essential for the reliable and continuous functioning of infrastructure systems. In this paper, we propose a risk assessment framework for storm sewer networks considering both hydraulic capacity and asset deterioration. The method is designed for a city-scale analysis and can provide an insightful result even when there is incomplete information. The objective is to assign a relative risk score to each pipe to inform replacement priorities. Moreover, we adopt a dynamic framework to proactively assess risk in different time horizons to investigate the impact of climate change and urbanization. A Dynamic Bayesian Network (DBN) model is used to capture dependencies among indicators, quantify uncertainty, and update belief when new information becomes available. Geographic information system (GIS) applications are used to collect and process model input data as well as visualize analysis results. Finally, the method is demonstrated on a storm sewer network in the city of Vernon, Canada. [ABSTRACT FROM AUTHOR]

Municipal stormwater systems are designed to collect, transport, and discharge precipitation from a defined catchment area into local surface waters. However, these discharges may contain unsafe levels of fecal waste. Paired measurements of Escherichia coli, precipitation, three land use metrics determined by geographic information system (GIS) mapping, and host-associated genetic markers indicative of human (HF183/BacR287 and HumM2), ruminant (Rum2Bac), dog (DG3), and avian (GFD) fecal sources were assessed in 231 urban stream samples impacted by two or more municipal stormwater outfalls. Receiving water samples were collected twice per month (n = 24) and after rain events (n = 9) from seven headwaters of the Anacostia River in the District of Columbia (United States) exhibiting a gradient of impervious surface, residential, and park surface areas. Almost 50% of stream samples (n = 103) were impaired, exceeding the local E. coli single sample maximum assessment level (410 MPN/100 ml). Fecal scores (average log10 copies per 100 ml) were determined to prioritize sites by pollution source and to evaluate potential links with land use, rainfall, and E. coli levels using a recently developed censored data analysis approach. Dog, ruminant, and avian fecal scores were almost always significantly increased after rain or when E. coli levels exceeded the local benchmark. Human fecal pollution trends showed the greatest variability with detections ranging from 9.1% to 96.7% across sites. Avian fecal scores exhibited the closest connection to land use, significantly increasing in catchments with larger residential areas after rain events (p = 0.038; R2 = 0.62). Overall, results demonstrate that combining genetic fecal source identification methods with GIS mapping complements routine E. coli monitoring to improve management of urban streams impacted by stormwater outfalls. [ABSTRACT FROM AUTHOR]

At the interface of geography with public health in the urban environment there seems to be no controversy about the importance of sanitation. This article addresses the importance of the proliferation of animal vectors in underground spaces built to meet basic sanitation, in particular sewer and storm drainage galleries. The methodology used was to analyze reports of these proliferations in the literature as well as the diseases linked by these vectors. Although these spaces are essential and necessary especially in large urban centers, embarrassingly they offer excellent breeding conditions for vector animals such as cockroaches, brown rats, mosquitoes and flies causing permanent threats to public health by linking different diseases and maintaining epidemics. However, understandably there are few epidemiological studies qualifying the importance of infestations in these spaces for public health. These infestations must be understood as an adverse ecological effect and not sufficient to compromise the solid benefit ratio between basic sanitation and public health. But the unequivocal presence and participation of these animals in linking important diseases to public health must be considered in specific research and to seek constructive adjustments in these underground spaces to mitigate these adverse effects. [ABSTRACT FROM AUTHOR]

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The paper presents the results of stationary, detailed studies on the variability of the mutual share of two fluvial loads, i.e., suspended solids and dissolved material during floods caused by rainstorm, continuous rainfalls and snowmelt in selected rivers (Silnica, Sufraganiec) draining small catchments in central Poland, including two characterized by a high level of urbanization. Irrespective of the origin of the flood, the share of suspended solids load did not exceed 80% in urbanized catchments, in suburban catchments—44%, and in forest catchments—32%. In the former, the gradient of the increase in the share of suspended solids and concentration time in the first phase of the flood was several times higher than in the other catchments. It was proved that statistically significant relationships exist between the share of sealed surfaces (roads, car parks, roofs, etc.) in the total catchment area and the average share of suspended solids, both in the rising and falling phase of the flood wave, regardless of their origin. Similar relationships were documented by analyzing: the density of the drainage network (storm sewers, roads, etc.)—the share of suspension. The obtained results have an interesting cognitive aspect and in practice are used for the development of hydrotechnical documentation related to water management in the city. [ABSTRACT FROM AUTHOR]

The article discusses how working holiday visas in Australia now include cleanup after cyclones as a permitted activity for backpackers. This change was made in response to recent cyclones and flooding in Northern Queensland. However, the article highlights the increased risk of exposure to melioidosis, a potentially fatal bacterial infection, during cleanup operations due to contact with contaminated water and soil. The author suggests that future travel health advice for backpackers should include preventive measures, treatment of wounds, and the importance of seeking medical attention if feeling unwell. [Extracted from the article]

Abstract—The results of a bacterioplankton study (total abundance; saprophytic, hydrocarbon oxidizing, and phenol resistant bacteria; total microbial count; and coliform bacteria) in an urbanized tributary of Lake Onego in 2015 are presented. The lower reaches of the Lososinka River flow over the territory of the city of Petrozavodsk (Karelia) and receive 14 untreated storm runoff streams from the municipal storm sewers. Differences in the temporal abundance dynamics of bacteria, which are indicators of oil pollution, the sanitary condition, and saprobity, were found between the reference and urban parts of the river. These variations are not related to the hydrological and thermal regime of the river and reflect the impact of the pollutant discharge from the urban area on the formation of the bacterial community of the river. The study revealed a significant increase in all the studied indicators of the quantitative development of bacterioplankton in the urban part of the river as compared to the reference part. The number of heterotrophic bacteria of various ecological–trophic groups decreases in the lake water by a factor of 8–16 already at a distance of 500 m from the mouth of the river due to dilution. A significant decrease in the numbers of hydrocarbon oxidizing bacteria in the river water and an increase in sanitary-indicative microorganisms are shown to have occurred over four years. Within the city limits of Petrozavodsk, the Lososinka River has been assessed as polluted with petroleum products, as well as organic substances of fecal origin and unfit for recreation based on the level of the indicator bacteria. [ABSTRACT FROM AUTHOR]