Search Results (289)

This article examines the effects of climate change on the 32 million inhabitants of the Megalopolis of Central Mexico (MCM), which is threatened by chaotic urbanization, land-use changes, the deforestation of the Forest of Water by organized crime, unsustainable agriculture, and biodiversity loss. Expensive hydraulic management extracting water from deep aquifers, long pipes exploiting water from neighboring states, and sewage discharged outside the endorheic basin result in expensive pumping costs and air pollution. This mismanagement has increased water scarcity. The overexploitation of aquifers and the pollution by toxic industrial and domestic sewage mixed with rainfall has increased the ground subsidence, damaging urban infrastructure and flooding marginal neighborhoods with toxic sewage. A system approach, satellite data, and participative research methodology were used to explore potential water scarcity and weakened water security for 32 million inhabitants. An alternative nature-based approach involves recovering the Forest of Water (FW) with IWRM, including the management of Natural Protected Areas, the rainfall recharge of aquifers, and cleaning domestic sewage inside the valley where the MCM is found. This involves recovering groundwater, reducing the overexploitation of aquifers, and limiting floods. Citizen participation in treating domestic wastewater with eco-techniques, rainfall collection, and purification filters improves water availability, while the greening of urban areas limits the risk of climate disasters. The government is repairing the broken drinking water supply and drainage systems affected by multiple earthquakes. Adaptation to water scarcity and climate risks requires the recognition of unpaid female domestic activities and the role of indigenous people in protecting the Forest of Water with the involvement of three state authorities. A digital platform for water security, urban planning, citizen audits against water authority corruption, and aquifer recharge through nature-based solutions provided by the System of Natural Protected Areas, Biological and Hydrological Corridors [SAMBA] are improving livelihoods for the MCM’s inhabitants and marginal neighborhoods, with greater equity and safety. Full article

Accelerating urbanization and the intensifying pace of climate change have heightened the occurrence of urban pluvial flooding, threatening urban sustainability. As the preferred approach to urban stormwater management, coupled gray and green infrastructure (GI–GREI) integrates GREI’s rapid runoff conveyance with GI’s infiltration and storage capacities, and their siting and scale can affect life-cycle cost (LCC) and urban drainage system (UDS) resilience. Focusing on Fengxi New City, China, this study develops a multi-objective optimization framework for the GI–GREI system that integrates GI suitability and pipe-network importance assessments and evaluates the Pareto set through entropy-weighted TOPSIS. Across multiple rainfall return periods, the study explores optimal trade-offs between UDS resilience and LCC. Compared with the scenario where all suitable areas are implemented with GI (maximum), the TOPSIS-optimal schemes reduce total life-cycle cost (LCC) by CNY 3.762–4.298 billion (53.36% on average), rebalance cost shares between GI (42.8–47.2%) and GREI (52.8–57.2%), and enhance UDS resilience during periods of higher rainfall return (P = 20 and 50). This study provides an integrated optimization framework and practical guidance for designing cost-effective and resilient GI–GREI systems, supporting infrastructure investment decisions and climate-adaptive urban development. Full article

To mitigate the impacts of urbanisation and the attendant surface sealing, appropriate measures are required when adapting urban spaces and drainage infrastructure. In this context, the deployment of Sustainable Drainage Systems (SuDSs) has emerged as a viable alternative, delivering highly positive outcomes by enhancing hydrological, hydraulic and landscape performance while restoring ecosystem services to the community. This study evaluates the relative performance of five SuDS typologies, green roofs, bioretention cells, infiltration trenches, permeable pavements, and rain barrels, implemented in a 64 ha subbasin of the metropolitan area of Barcelona, Spain. Using Giswater integrated with the SWMM, the stormwater drainage network was modelled under multiple rainfall scenarios. Performance was assessed using two qualitative indicators, the junction index (I_j) and the conduit index (I_c), which measure surcharge levels in manholes and pipes, respectively. The results show that SuDS implementation affecting 42.8% of the drained area can enhance network performance by 35.6% and reduce flooded junctions by 67%. Among the typologies, rain barrels and bioretention cells were the most effective. The study concludes that SuDS construction, supported by open-source tools and performance-based indicators, constitutes a replicable and technically robust strategy for mitigating the effects of surface sealing and increasing urban resilience. Full article

Rapid urbanization in China has overwhelmed traditional drainage systems, resulting in frequent flooding and water pollution in densely populated urban areas. This study focuses on the East Lake core area of Wuhan, proposing a deep tunnel drainage system to improve sewage storage and conveyance capacity. A pilot-scale pipe model was employed to determine the critical non-silting velocity for full-pipe sewage flow. Based on projected dry-season inflows and intercepted combined sewer discharges, the design capacities for pumping stations and pretreatment facilities were defined. A three-dimensional gas–liquid two-phase numerical model was used to simulate inflow shaft hydraulics at Erlangmiao, Luobuzui, and Wudong pretreatment stations. Simulation results confirm that all shafts meet energy dissipation and ventilation requirements, with uniform flow and velocity distributions that could be obtained by a vortex-type shaft. The system not only mitigates regional environmental challenges but also shows significant social, environmental, and economic benefits. Overall project design, applied methodology, simulation study, and outcomes could provide a valuable reference to deep tunnel drainage design and research. Full article

Old urban districts, characterized by complex drainage networks, heterogeneous surfaces, and high imperviousness, are particularly susceptible to flooding during extreme rainfall. In this study, the moat drainage district of Xi’an was selected as the research area. A refined hydrologic–hydrodynamic simulation and an assessment of drainage and flood-retention capacities were conducted based on the coupled GAST–SWMM model. Results show that the model can accurately capture the rainfall–surface–pipe–river interactions and reproduce system responses under different rainfall intensities. The box culvert’s effective regulation capacity is limited to 1- to 2-year return periods, beyond which overflow rises sharply, with overflow nodes exceeding 80% during a 2-year event. The moat’s available storage capacity is 17.20 × 10⁴ m³, sufficient for rainfall events with 5- to 10-year return periods. In a 10-year return period event, the box culvert overflow volume (12.56 × 10⁴ m³) approaches the upper limit, resulting in overtopping. These findings provide a scientific basis for evaluating drainage efficiency and guiding flood control management in old urban districts. Full article

With the rapid development of coastal and nearshore engineering projects in China, geotextile pipe and bag (GPB) structures have been increasingly applied in marine land reclamation and coastal protection works. To better understand the mechanical behavior of GPB structures on soft soil foundations, this study conducts a systematic investigation into the mechanical properties of both soft soils and GPBs using a physical model test system. By integrating numerical simulations, the stress–deformation characteristics of GPB structures on soft soils and the evolution of pore pressure are further analyzed. The results indicate that the compression curve of soft soil exhibits significant nonlinearity, with silt showing higher apparent compressibility than silty clay. Experimental data yielded the compression coefficient λ and rebound coefficient μ for both soil types. As consolidation pressure increases, deviatoric stress in the soft soil rises notably, demonstrating typical strain-hardening behavior. Based on these findings, the critical state effective stress ratio M was determined for both soil types. The study also establishes the development laws of cohesion c and friction angle φ during soil consolidation, as well as the variation of pore water pressure under different confining pressures. Interface tests clarify the relationships between cohesion and friction angle at the interfaces between geotextile pipe bags and sand, and between adjacent pipe bag layers. Numerical simulations reveal that the reclamation construction process significantly influences structural horizontal displacement. Significant stress concentration occurs at the toe of the slope, while the central portion of the pipe-bag structure experiences maximum tensile stress—still within the material’s allowable stress limit. The installation of drainage boards effectively accelerates pore pressure dissipation, achieving nearly complete consolidation within one year after construction. This research provides a scientific foundation and practical engineering guidance for assessing the overall stability and safety of (GPB) structures on soft soil foundations in coastal regions. Full article

Glass fiber (GF) reinforced unsaturated polyester resin (UP) composites are used in cured-in-place pipe (CIPP) rehabilitation technology of drainage systems due to their low cost and excellent force chemical properties. However, the weak interfacial compatibility between GF and the polymer matrix limits the stress transfer efficiency. Herein, a strategy of a polyhydric boehmite (AlOOH) layer coated on GF (GF-AlOOH) was developed for improving the mechanical properties of UP composites, and the enhancement effects of the coating process were analyzed. The AlOOH-modified GFs significantly improved the flexural and tensile strengths of the modified composites by 41.21% and 21.05%, respectively. Moreover, the enhancement mechanism was explored by analyzing the surface chemical structure of GF-AlOOHs. The nano-AlOOH was grafted on the GF surface by O=Al–OH. Meanwhile, the increase in the mechanical properties of UP/GF-AlOOH was mainly attributed to the combined effect of mechanical interlocking interaction, covalent bonding and hydrogen bonding, which improved the interfacial adhesion between GF and UP. In summary, this work provides effective guidance for achieving high-quality interfaces in GF composites and offers important insights into designing durable and cost-effective materials for CIPP rehabilitation and broader infrastructure applications. Full article

Rapid urbanization and frequent extreme events have made urban flooding a growing threat to residents. This issue is acute in old urban districts, where extremely limited land resources, outdated standards and poor infrastructure have led to inadequate drainage and uneven pipe settlement, heightening flood risk. This study applies InfoWorks ICM Ultimate (version 21.0.284) to simulate flooding in a typical old urban district for six return periods. A risk assessment was carried out, flood causes were analyzed, and mitigation strategies were evaluated to reduce inundation and cost. Results show that all combined schemes outperform single-measure solutions. Among them, the green roof combined with pipe optimization scheme eliminated high-risk and medium-risk areas, while reducing low-risk areas by over 78.23%. It also lowered the ponding depth at key waterlogging points by 70%, significantly improving the flood risk profile. The permeable pavement combined with pipe optimization scheme achieved similar results, reducing low-risk areas by 77.42% and completely eliminating ponding at key locations, although at a 50.8% higher cost. This study underscores the unique contribution of cost-considered gray-green infrastructure retrofitting in old urban areas characterized by land scarcity and aging pipeline networks. It provides a quantitative basis and optimization strategies for refined modeling and multi-strategy management of urban waterlogging in such regions, offering valuable references for other cities facing similar challenges. The findings hold significant implications for urban flood control planning and hydrological research, serving as an important resource for urban planners engaged in flood risk management and researchers in urban hydrology and stormwater management. Full article

Urban drainage pipelines are essential components of smart city infrastructure, supporting the safe and sustainable operation of underground systems. However, internal corrosion in pipelines poses significant risks to structural stability and public safety. In this study, we propose an enhanced semantic segmentation framework based on High-Resolution Network Version 2 (HRNetV2) to accurately identify corroded regions in Traditional closed-circuit television (CCTV) images. The proposed method integrates a Convolutional Block Attention Module (CBAM) to strengthen the feature representation of corrosion patterns and introduces a Lightweight Pyramid Pooling Module (LitePPM) to improve multi-scale context modeling. By preserving high-resolution details through HRNetV2’s parallel architecture, the model achieves precise and robust segmentation performance. Experiments on a real-world corrosion dataset show that our approach attains a mean Intersection over Union ($mIoU$) of 95.92 $\pm$ 0.03%, $Recall$ of 97.01 $\pm$ 0.02%, and an overall $Accuracy$ of 98.54%. These results demonstrate the method’s effectiveness in supporting intelligent infrastructure inspection and provide technical insights for advancing automated maintenance systems in smart cities. Full article

Dual-inlet tail escapes, combining an orifice and a weir, are key hydraulic structures that evacuate excess water from canal termini during maintenance and protect berms by discharging surplus irrigation flows. Conventional sizing methods typically depend on trial and error, which is time-consuming and may yield suboptimal design. This study introduces a graphical design approach and a MATLAB-based tool, TAILOPT, developed to streamline tail escape design. The tool incorporates both the Fanning and Darcy–Weisbach friction formulations for head loss estimation and can automatically generate an “.inp” file for EPA-SWMM, enabling direct unsteady-state hydraulic assessment. This integration reduces design effort and supports evaluation of alternative hydraulic and drainage scenarios within a single workflow. Two applications illustrate the framework. The first shows that overly steep drainage slopes (Sp > 2%) are impractical, while vertical drops may require larger pipe diameters. The second application applies TAILOPT to a distributary canal, determining the optimal pipe size and verifying its performance in EPA-SWMM under emergency surplus flow and routine dewatering conditions. The results demonstrate that the method yields economical, robust, and practitioner-friendly designs; however, modeling simplifications, such as assuming continuously submerged orifice flow, can introduce minor deviations in the predicted channel emptying times. Full article

Reducing carbon emissions in buildings requires a holistic approach that extends beyond structural materials and looks at the services within, such as Building Drainage Systems (BDS). However, limited scientific research has addressed the environmental impacts of BDS, and, to date, no studies have systematically analysed embodied carbon emissions from a design code perspective. This study evaluates the embodied carbon emissions of BDS based on calculations from four major international design codes, BS EN 12056 (Europe), IPC and UPC (USA), and AS/NZS 3500 (Australia/New Zealand), using polyvinyl chloride (PVC) pipework. System configurations recommended in the design codes, such as primary ventilation and secondary ventilation systems, were evaluated as well as a fully active system incorporating Air Admittance Valves (AAVs) and Positive Pressure Relief Devices (PPRDs) across a range of building sizes from 10 to 100 storeys. The findings reveal substantial differences in recommended pipe sizes among the codes, directly impacting total pipework material use and, in turn, the embodied carbon emissions. A life cycle assessment (LCA) of PVC pipework demonstrates that the design recommendations in the European code generally lead to lower embodied carbon emissions, while the IPC and UPCs result in significantly higher emissions, with the AS/NZS code falling in between. In contrast, the use of a fully active drainage system was shown to reduce embodied carbon emissions by up to 73% depending on the building size and the design code applied. As the sustainability of buildings and systems becomes more and more vital, the findings of this paper provide the foundations for integrating the sustainability metrics of BDS into design codes. This will provide practical guidance for engineers and regulators on how carbon savings in BDS design and construction can be achieved. Full article

Corrugated pipes are extensively used in engineering applications that require flexibility and enhanced heat exchange, such as drainage and compact heat exchangers, and recently as inner layers in cryogenic flexible hoses for offshore liquid ship-to-ship transfer. The great flexibility of these hoses makes them well-suited for deployment in dynamic and harsh marine environments. However, the corrugated geometry also induces flow separation, elevated turbulence, and intricate heat transfer behaviors. This study focuses on the flow and heat transfer characteristics in corrugated pipes with various geometries, addressing the current lack of systematic comparative studies on the performance of different Reynolds-Averaged Navier–Stokes (RANS) models in such configurations. Despite their limitations in accuracy compared to high-fidelity methods, RANS models remain the workhorse for engineering analysis due to their computational efficiency. This study employs several RANS models to simulate flow and heat transfer in three corrugated pipe geometries—sinusoidal (Sin), C-type, and U-type—over a Reynolds number range of O(10⁴) to O(10⁵) and assesses their performance against high-fidelity Large Eddy Simulation benchmarks. The results show that prediction accuracy decreases with increasing corrugation depth, with the most significant errors in trough regions where reverse flow dominates, and that the choice of turbulence model has a strong influence on the predicted flow and heat transfer behavior. Among all models, the $k-ϵ$ models overall provide the most consistent and accurate predictions for friction factor, velocity distribution, and Nusselt number, while the $k-\omega$ models perform the worst. The Reynolds Stress Model improves friction factor prediction accuracy at high Reynolds numbers and provides marginally better accuracy in mean Nusselt number prediction, but its advantages are limited relative to its substantially higher computational cost. The Standard $k-ϵ$ model with Enhanced Wall Treatment demonstrates robust and balanced performance across geometries and flow regimes, making it a practical choice for engineering use. This work provides engineers and researchers guidance for choosing RANS models that balance accuracy and computational efficiency in simulations of LNG ship-to-ship transfer, compact heat exchangers, and other industrial systems that employ corrugated pipes. Full article

With climate change, the frequency and severity of localized heavy rainfalls are increasing. Thus, for urban drainage networks (UDNs), particularly those in aging cities such as Seoul, Republic of Korea, flood risk management challenges are mounting. Conventional design standards typically apply uniform roughness coefficients based on new pipe conditions, neglecting the ongoing performance degradation from physical influences. This study introduces a methodology that systematically incorporates pipe age and size into roughness coefficient scenarios for higher-accuracy 1D–2D rainfall–runoff hydrologic–hydraulic simulations. Eleven roughness scenarios (a baseline and ten aging-based scenarios) are applied across seven UDNs using historical rainfall data. The most representative scenario (S3) is identified using a Euclidean distance metric combining the peak water-level error and root mean square error. For two rainfall events, S3 yields substantial increases in the simulated mean flood volumes (75.02% and 76.45%) compared with the baseline, while spatial analysis reveals significantly expanded inundation areas and increased flood depths. These findings underscore the critical impact of pipe deterioration on hydraulic capacity and demonstrate the importance of incorporating aging infrastructure into flood modeling and UDN design. This approach offers empirical support for updating UDN design standards for more resilient flood management. Full article

To investigate the safety risks associated with gas tunnel coal uncovering, a physical and mechanical model of the critical safety rock pillar is proposed through a combination of theoretical analysis, numerical simulation, and field testing. Based on the principles of energy conservation and catastrophe theory, an expression for calculating the critical safety for rock pillar thickness is derived. The effects of tunnel radius, burial depth, axial stress, coal seam dip angle, and gas pressure on the critical thickness are systematically analyzed. The results indicate that the critical safety of rock pillar thickness increases with the tunnel radius, burial depth, gas pressure, and axial stress. Moreover, as the tunnel radius increases, the growth rate of the critical thickness also increases. Conversely, as the burial depth increases, the growth rate of the critical thickness decreases. For gas pressure and axial stress, the growth rate remains relatively constant. Using a tunnel project in Hunan as a case study, theoretical analysis yields a critical safety rock pillar thickness of 3.95 m. A corresponding numerical model is developed to simulate this scenario, and the simulation results align well with the theoretical predictions. Based on these findings, a combined treatment scheme of “advanced small-pipe grouting + gas drainage and pressure relief” is proposed for excavation upon reaching the critical rock pillar thickness. This scheme successfully ensures safe tunnel passage through the coal seam. Full article

Tunnel drainage pipes are prone to blockage due to mineral crystallization and deposition from water, which seriously affects the long-term stable operation of the drainage system and compromises the safety of tunnel structures. To address this issue, it is imperative to develop efficient anti-crystallization technologies to extend the service life of drainage systems. In this study, a series of anti-crystallization performance experiments on tunnel drainage pipes were designed and conducted based on magnetic treatment technology. The inhibitory effects of magnetic fields on crystal formation and deposition were systematically investigated under various conditions, including different magnetic field intensities, magnetic field coverage angles, magnetic field orientations, and water flow velocities. The results indicate that under magnetic influence, the crystal morphology inside the pipes changed from regular cubic structures to irregular forms with rough surfaces and loose structures, showing a transformation trend from calcite to aragonite and vaterite. Compared with conventional PVC pipes, the anti-crystallization effect was most pronounced under the following conditions: magnetic field intensity of 40 Gs, coverage angle of 90°, vertical magnetic field orientation, and higher water flow velocity. The findings of this study provide a novel approach to mitigating crystallization-induced blockages in tunnel drainage systems and contribute to reducing tunnel-related pathologies such as lining cracks, water seepage, and structural deterioration caused by poor drainage. Full article