Search Results (69)

Green roofs are used as nature-based solutions for urban stormwater management and for improving the thermal performance of buildings. Their hydrological performance depends on structural properties and rainfall characteristics, but the relative importance of these factors has not been fully quantified. Therefore, this study aimed to identify the key variables controlling the hydrological effectiveness of a green roof. A conceptual model of a flat roof representing a typical single-family building in south-eastern Poland was developed in the Storm Water Management Model (SWMM), with a modeled roof area of 232 m² and 100% of the roof surface covered by the green roof LID system. A total of 24,576 simulation cases were analyzed, considering different values of soil thickness, berm height, initial saturation, vegetation-related storage, rainfall duration, rainfall probability, and rainfall temporal distribution. The hydrological response was evaluated using peak runoff reduction and cumulative runoff volume ratio determined at selected times after rainfall. Predictive models based on the eXtreme Gradient Boosting (XGBoost) algorithm were developed, and their interpretation was performed using the SHapley Additive exPlanations (SHAP) method. The main novelty of the study is its application-oriented framework combining SWMM simulations, XGBoost modeling, and SHAP explainability to distinguish the factors controlling peak runoff reduction and delayed runoff release from a green roof. The results showed that peak runoff reduction ranged from 10.97% to 100.00%, with a median of 99.91%, indicating a generally high capacity of the analyzed system to attenuate peak flow. In contrast, the cumulative runoff volume ratio increased over time, with median values rising from 0.05% immediately after rainfall to 7.91% after 24 h, confirming the significant retention and detention potential of the green roof. SHAP analysis revealed that peak runoff reduction was governed primarily by berm height, whereas cumulative runoff volume was controlled mainly by initial substrate saturation. The results confirm that different mechanisms control short-term and long-term green roof performance. Full article

Storm-driven turbidity is a major water-quality concern in urban watersheds, reflecting the mobilization and transport of fine sediment during runoff events. This study examines how seasonal storm characteristics influence turbidity and associated sediment transport responses in the Middle Fork of Beargrass Creek, Louisville, Kentucky, over a two-year period. Forty-one erosive storm events were identified and characterized using high-resolution rainfall data to capture storm magnitude and structure. Study objectives were to: (1) quantify event-scale turbidity responses to erosive storms, (2) compare upstream and downstream turbidity behavior to assess spatial variability, (3) evaluate seasonal variation in these relationships, and (4) assess implications for sediment-focused best management practice (BMP) design. Event-based regression models related downstream turbidity to lagged upstream turbidity and downstream erosivity. Turbidity ratios and turbidity–discharge hysteresis characterized spatial and temporal sediment transport dynamics. Results showed that winter and spring storms exhibited longer durations, stronger upstream–downstream turbidity coupling, and more stable lag relationships, indicating integrated sediment transport. Short-duration, high-intensity summer storms produced elevated turbidity ratios, pronounced clockwise hysteresis, and greater model sensitivity, consistent with localized sediment mobilization. Findings support seasonally adaptive BMP strategies, with volume-reduction approaches most effective during winter–spring and source control measures critical during summer-fall. Full article

The reconstruction of detrital flux, paleoclimate, paleosalinity, paleo-primary productivity, paleohydrodynamic conditions, and paleo-water depth enhances understanding of sedimentary processes and their drivers during deep-time greenhouse-icehouse transitions, such as the Eocene–Oligocene transition. This study uses detailed geochemical analyses of major oxides and trace elements in sediment samples collected from the Beni Suef Formation (Bartonian–Priabonian) and the Maadi Formation (Priabonian) in the southern Tethys shelf (Egypt, northeastern Desert). Detrital proxies, including Si/Al, Ti/Al, and Zr/Al, indicate an enhanced influx of terrigenous sediments in the middle portion of the Qurn Member of the Beni Suef Formation, as further supported by noticeable facies variations, particularly the transition from shale to coarser silt- and sand-sized fractions. Paleoclimate indicators (Sr/Ba, Rb/Sr, K₂O/Al₂O₃, and Sr/Cu) point to a climatic shift from humid to arid conditions, consistent with the regional Late Eocene aridification across the Tethyan realm. Paleosalinity proxies (Sr/Ba, Ca/Al, and Mg/Al×100) suggest episodic intensification of open-marine influence and a reduction in freshwater input, with an upsection increase in Sr/Ba ratios, reflecting phases of enhanced marine water settings or decreased terrestrial runoff. Primary productivity was evaluated using multiple geochemical proxies, including P, Ni/Al, Cu/Al, P/Al, P/Ti, and Babio ratios. These collectively indicate generally low primary productivity interrupted by intervals of enhanced paleoproductivity or increased organic matter export to the sediments. This interpretation is further supported by the low total organic carbon (TOC) values. These results highlight the sensitivity of the southern Tethys shelf to Middle–Late Eocene climatic variability and the key role of prevailing paleoenvironmental conditions in controlling sediment supply, water chemistry, and biological productivity. Full article

Urban flood peak mitigation by green infrastructure (GI) is fundamentally a timing problem. Because GI storage is finite, interception occurs only within a brief active window; whether it reduces the outlet peak depends on GI placement in the network, routing lags, and rainfall timing. Here, we develop a timescale-based framework that links outlet peak reduction to the alignment among within-storm temporal structure, network response, and GI filling dynamics, providing a compact way to interpret when different network positions become most effective under a fixed GI design. Starting from a general convolution representation of runoff generation, interception, and routing, we show that peak reduction efficiency and location ranking can be organized by two nondimensional ratios—comparing storm duration and network response time to a characteristic GI filling time—plus simple descriptors of within-storm temporal structure. Under uniform rainfall, these ratios yield an interpretable regime diagram with analytical transition curves between downstream-, mid-network-, and upstream-optimal placement for a generic dispersive routing representation. Relaxing the uniform-rainfall assumption shows that within-storm variability can substantially reorganize these regimes because storm timing controls both how long GI storage remains available before it fills and which routed contributions overlap to form the outlet peak. Highly concentrated storms and storms with early internal peaks are especially likely to reorder the ranking of candidate locations relative to the uniform-rainfall baseline. Using 2351 observed hourly storm events evaluated across virtual catchments spanning fast to slow network responses, we quantify how often realistic event structure alters the optimal location and the regret associated with adopting a uniform design storm. The results motivate robustness-oriented placement strategies based on ensembles of plausible storm temporal structures, organized within the proposed timescale diagram rather than reliance on a single design hyetograph. Full article

Background/Objectives: The objective of this study was to ascertain whether photon-counting CT angiography (PCD-CTA) can optimize image quality for the visualization of perforating arteries for planning fibular transplant procedures in comparison to energy-integrating CT angiography (EID-CTA). Methods: In this retrospective single-center study, all patients who underwent preoperative CT of the peripheral runoff for planning between October 2021 and July 2023 were consecutively included. PCD-CTA was performed in standard resolution mode as 55 keV images with 90 mL of iodine-containing contrast agent or alternatively, an EID-CTA as a low-kV scan with 110 mL of contrast agent. The raw data were reformatted using comparable soft vascular and sharp regular convolution kernels, slice thickness/increment, and field of view. Contrast-to-noise ratio was calculated for objective image quality. Subjective evaluation was based on a rating by three radiologists using a five-point Likert scale (criteria: overall image quality, luminal attenuation, vessel sharpness, and perforator depiction). Results: Of the 26 patients who were screened, 9 could be included in each group, while 8 were excluded due to incomplete reconstructions. The reduction in contrast agent dose resulted in a non-significant decrease in luminal attenuation on PCD-CTA (452.5 ± 53.6 HU vs. 465.5 ± 99.6 HU; p = 0.375). The image noise was considerably lower for PCD-CTA (21.1 ± 1.0 HU vs. 32.9 ± 1.6 HU; p < 0.001). This resulted in a significantly higher contrast-to-noise ratio (CNR) for sharp kernel reconstructions (22.4 ± 3.5 vs. 14.5 ± 3.8; p < 0.001). No significant differences were observed for the soft vascular kernel. Subjective evaluation revealed a significant enhancement in overall image quality, vascular sharpness, and perforator depiction for PCD-CTA with sharp reconstructions. In contrast, soft kernel reconstructions and luminal attenuation demonstrated no substantial difference. Interrater agreement was good to excellent. Conclusions: PCD-CTA with sharp kernel reformatting has been demonstrated to yield superior image quality and perforator delineation of the fibular artery in comparison to standard EID-CTA. Full article

As China’s Sponge City Program (SCP) shifts towards retrofitting old communities, enhancing flood resilience is critical for sustainable urban renewal. However, engineering practice often encounters a performance inversion—characterized by high design evaluation scores but low operational efficiency. This issue largely stems from relying on the static importance of indicators while neglecting dynamic driving forces within the socio-technical system. To address this, this study aims to construct a Robust Causal Diagnostic Framework integrating Improved AHP, DEMATEL, and K-means clustering. Through a quadrant positioning and cluster locking mechanism, it identifies Hidden Leverage Factors (HLFs)—critical indicators typically assigned low weights but exerting strong driving forces. To demonstrate the practical application of this framework, an empirical analysis of H City’s DG Community was conducted, identifying residents’ willingness and design pertinence as the project’s HLFs. Optimization strategies based on this diagnosis were simulated using SWMM. Results show that the Annual Runoff Volume Capture Ratio increased by 44.45%, with significant improvements in peak flow reduction and water purification. This study facilitates a shift from empirical evaluation to precision diagnosis, offering a quantitative reference for enhancing urban flood resilience under complex social constraints. Full article

The pyrite bioretention system has been increasingly used to control dissolved nutrients in stormwater runoff. However, its low electron supply rate cannot adapt to the demand for denitrification under high nitrogen-loading conditions. To address this limitation, we constructed a mixed biochar–pyrite bioretention system (BP) by optimizing the structural composition of the fill media. Under simulated complex rainfall conditions, the nitrogen removal efficiency, by-product generation, and filler physicochemical properties of system were evaluated. Results demonstrated that the BP system significantly enhanced denitrification performance, achieving average NO_x⁻-N and TN removal rates of 63.3% and 67.8%, respectively. This represented improvements of 79.1% and 45.9% over the conventional pyrite bioretention system. Moreover, the composite system exhibited a sustained and effective denitrification even under low C/N ratio conditions. This enhancement is attributed to biochar’s dual role as an electron shuttle and an electron reservoir, which facilitated microbial nitrate reduction. XPS analysis further confirmed that biochar addition effectively reduced the oxidation degree of pyrite, thereby protecting it from rapid oxidative degradation. Microbial analysis revealed that biochar supplementation in the BP system increased microbial diversity in the saturated zone, which contributed to improved ecosystem function and stability, including the promotion for key denitrification processes. Full article

This study proposes the Sponge City+ parametric design toolkit, which integrates low-impact development (LID) measures into urban design to support compliance checking, runoff risk analysis, and optimization of design alternatives. Compliance is evaluated using the annual runoff volume capture ratio (AVCR) calculated via the Volume Method, which is the core criterion in sponge city standards. The toolkit combines a measures database, runoff volume control functions, and runoff simulation functions to evaluate and compare design alternatives. Its applicability was tested through case studies of three university campuses in China. These cases were used to: (1) conduct a sensitivity analysis of the toolkit’s response to different LID strategies, ranking three typical LID measures (sunken green spaces > permeable pavements > green roofs) in terms of their contribution to runoff control; (2) perform multi-objective optimization considering cost, runoff control, and peak reduction, which, under ordinary PC computational capacity, efficiently identified 27 qualified solutions out of more than 5000 samples, thereby providing a broader set of design choices while ensuring compliance with runoff control requirements; and (3) demonstrate a design optimization process based on runoff visualization, where human–computer interaction helped avoid potential flood risks during the early design stage. This study demonstrates the potential of a parametric workflow to bridge disciplinary boundaries and support the achievement of global sustainability goals. Full article

Changes in the diversion characteristics of three outlets along Jingjiang River are of vital importance to the adjustment of river–lake relationships. This study analyzed the mechanism of periodic changes in the diversion ratio of the three outlets along the Jingjiang River after the storage of the Three Gorges Reservoir. It used the latest measured flow and sediment data. The analysis was conducted from the perspective of changes in the main stream regime at the three outlets along the Jingjiang River and the erosion and deposition trend of the floodway at the three outlets. On such a basis, the contribution ratio of three factors was analyzed quantitatively. These factors are Jingjiang River runoff reduction, reservoir regulation action, and diversion capacity drop. This analysis comprehensively considered the diversion capacity of the floodway at three outlets. It also considered the annual runoff volume and runoff process of the Jingjiang River mainstream. The purpose was to reveal the change laws of water resource quantity and response mechanism of Dongting Lake area under the new flow and sediment conditions. This will provide technical support for the sustainable management of water resources in the basin and the adaptive operation of reservoirs. The analysis results indicated that the diversion volume reduction at the three outlets along Jingjiang River is jointly caused by the regulation of the Three Gorges Reservoir and the runoff volume of the incoming flows of Jingjiang River. Seen from the proportion, the reservoir regulation action takes up 35% before the Three Gorges Reservoir is filled to 175 m, and less runoff of Jingjiang River takes up 65%; after the reservoir runs normally when filled to 175 m, the reservoir regulation action takes up 63%, the proportion of the diversion capacity drop of the three outlets causing diversion volume reduction takes up 2.5%, and less runoff of Jingjiang River takes up 34.5%. Full article

Urban green hearts provide essential ecosystem services, including carbon sequestration, water purification, and hydrological regulation. The Green Heart Area of the Chang-Zhu-Tan Urban Agglomeration in Hunan Province, China, is the largest globally, and plays a critical role in regional water management. These functions are increasingly threatened by intensive land-use, while soil, as the foundational ecosystem component, mediates water retention, nutrient cycling, and erosion resistance. This study examined the effects of four land-use types—cropland, plantation, arbor woodland, and other woodland—on soil particle composition and key nutrients (organic carbon, total nitrogen, and total phosphorus). Statistical comparisons among land-use types were performed. Results indicated that silt was the dominant soil fraction across all land-uses (64–72%). Arbor woodland exhibited significantly higher sand content (29%) compared to cropland (19%; p < 0.05), suggesting improved water permeability and erosion resistance. Cropland showed elevated nutrient levels, with TN (1450.32 mg·kg⁻¹) and TP (718.86 mg·kg⁻¹) exceeding both national averages and those in arbor woodland. Coupled with acidic soil conditions (pH 5.23) and lower stoichiometric ratios (C/N: 10.82; C/P: 35.67; N/P: 3.29), these traits indicate an increased risk of nutrient leaching in croplands. In contrast, arbor woodland displayed more balanced C:N:P ratios (C/N: 12.21; C/P: 48.05; N/P: 3.84), supporting greater nutrient retention and aggregate stability. These findings underscore the significant influence of land-use type on soil ecological functions, including water infiltration, runoff reduction, and climate adaptability. The study highlights the importance of adopting conservation-oriented practices such as reduced tillage and targeted phosphorus management in croplands, alongside reforestation with native species, to improve soil structure and promote long-term ecological sustainability. Full article

Straw fiber curtain contains a plant fiber blanket woven from crop straw, which is mainly used to protect embankment slopes from rainwater erosion. To investigate the erosion control performance of slopes covered with straw fiber curtains of different structural configurations, physical model tests were conducted in a 95 cm × 65 cm × 50 cm (length × height × width) test box with a slope ratio of 1:1.5 under controlled artificial rainfall conditions (20 mm/h, 40 mm/h, and 60 mm/h). The study evaluated the runoff characteristics, sediment yield, and key hydrodynamic parameters of slopes under the coverage of different straw fiber curtain types. The results show that the A-type straw fiber curtain (woven with strips of straw fiber) has the best effect on water retention and sediment reduction, while the B-type straw fiber curtain (woven with thicker straw strips) with vertical straw fiber has a better effect regarding water retention and sediment reduction than the B-type transverse straw fiber curtain. The flow of rainwater on a slope covered with straw fiber curtain is mainly a laminar flow. Straw fiber curtain can promote the conversion of water flow from rapids to slow flow. The Darcy-Weisbach resistance coefficient of straw fiber curtain increases at different degrees with an increase in rainfall time. Full article

Urbanization and climate change have disrupted natural water circulation by increasing impervious surfaces and altering rainfall patterns, leading to reduced groundwater infiltration, deteriorating water quality, and heightened flood risks. This study investigates the application of Low Impact Development (LID) and flood control facilities as structural measures to address these challenges in the upper watershed of the Fucha River in Bogotá, Colombia. The methodology involved analyzing watershed characteristics, defining circulation problems, setting hydrological targets, selecting facility types and locations, evaluating performance, and conducting an economic analysis. To manage the target rainfall of $26.5$$\mathrm{m}$$\mathrm{m}$ under normal conditions, LID facilities such as vegetated swales, rain gardens, infiltration channels, and porous pavements were applied, managing approximately 2362 ${\mathrm{m}}^3$ of runoff. For flood control, five detention tanks were proposed, resulting in a 31.8% reduction in peak flow and a 7.3% decrease in total runoff volume. The flooded area downstream was reduced by $46.8$$\mathrm{h}\mathrm{a}$, and the benefit–cost ratio was calculated at 1.02. These findings confirm that strategic application of LID and detention facilities can contribute to effective urban water cycle management and disaster risk reduction. While the current disaster management approach in Bogotá primarily focuses on post-event response, this study highlights the necessity of transitioning toward proactive disaster preparedness. In particular, the introduction and expansion of flood forecasting and warning systems are recommended as non-structural measures, especially in urban areas with complex infrastructure and climate-sensitive hydrology. Full article

Non-point source (NPS) pollution in agricultural land continues to rise despite urbanization in South Korea. NPS pollution management in rural areas has been conducted using Best Management Practices (BMPs) to reduce NPS pollution in rural areas. Among them, nature-based facilities are commonly used to reduce runoff NPS pollution. To design such facilities, it is necessary to determine the Water Quality Volume (WQv), which serves as a key indicator for evaluating the performance of pollution reduction facilities, as well as the estimation of the design rainfall intensity. These are critical factors for the design of the delineation of catchment areas and NPS pollution reduction. However, conventional methods for capacity estimation often rely on total area rather than considering the specific land use distribution, leading to lower pollution reduction efficiency and excessive project costs. Therefore, this study uses actual monitoring data from existing nature-based facilities, and an analysis was performed to establish a method for determining their optimal capacity while accounting for land use characteristics. A regression analysis was conducted based on the land use area ratio, and the results demonstrated that the proposed method yields similar or improved outcomes in terms of water quality improvement and economic feasibility compared to conventional capacity estimation methods. These findings highlight the importance of incorporating diverse land use distributions into capacity estimation for improving NPS pollution management efficiency by enhancing water quality and reducing project costs. Full article

The parameters of Low-Impact Development (LID) facilities significantly influence their operational performance and runoff control effectiveness at the site. Despite extensive research on LID effectiveness, limited studies have focused on optimizing design parameters at a community-wide scale, integrating both hydrological and statistical methodologies. A novel approach to optimizing LID design parameters was presented in this study. This study established a community-scale SWMM model, identified the key parameters by the Morris screening method, and determined the reasonable parameter ranges based on runoff control effects. The Response Surface Methodology (RSM) was applied to optimize the key parameters under different return periods and impervious area ratios. The results showed that key LID parameters for runoff volume control were the berm height of the surface layer of sunken greenbelt (SG_Surface_H), the conductivity of the soil layer of sunken greenbelt (SG_Soil_I), the permeability of the pavement layer of permeable pavement (PP_Pavement_I), and the thickness of the storage layer of permeable pavement (PP_Storage_T). The reasonable ranges were 50–265 mm, 5–80 mm/h, 50–140 mm/h, and 100–165 mm, respectively. The key LID parameters for peak flow reduction were SG_Surface_H, SG_Soil_I, PP_Pavement_I, and the berm height of the surface layer of vegetated swale (VS_Surface_H). The reasonable ranges were 50–260 mm, 5–50 mm/h, 50–195 mm/h, and 50–145 mm, respectively. The optimization results of LID parameters showed that for the runoff volume control rate, the optimization strategy involved increasing SG_Surface_H as the return period increased and when the impervious area ratio was large, especially in the rehabilitation of old communities. Meanwhile, the optimal value of SG_Soil_I for runoff volume control was greater than that for peak flow reduction. In contrast, the optimal value of PP_Pavement_I was larger for peak flow reduction. This study provides a significant reference for LID planning and design by emphasizing the optimization of LID design parameters. Full article

Urbanization necessitates Low Impact Development (LID) practices for sustainable development, but existing studies lack analysis about the comprehensive effect and optimal allocation of LID combination practices. To address this gap, this study conducted an in-depth analysis of the runoff control effects of individual and combined LID practices and pollutants under varying retrofit proportions, utilizing the Storm Water Management Model (SWMM). Four evaluation metrics were employed for parameter calibration and validation assessment to ensure the accuracy of the SWMM. The Response Surface Methodology (RSM) was then employed to optimize the retrofit proportions of LID practices due to its high efficiency and statistical rigor. The results showed that, under the same retrofit ratio, bio-retention (BC) has a better runoff reduction rate and pollutant removal rate. For example, when the retrofit proportion is 100%, the runoff pollutant removal rates of BC in Parcel 1 and Parcel 2 are 29.6% and 32.9%, respectively. To achieve a 70% runoff control rate, the optimal retrofit proportions for Parcel 1 were 67.5% for green roofs (GR), 92.2% for permeable pavements (PP), 88.9% for bio-retention cells (BC), and 50% for low-elevation greenbelts (LEG); these correspond to the proportions for Parcel 2 that were 65.1%, 68.1%, 82.0%, and 50%, respectively. In conclusion, this study provides scientific and technical support for urban planners and policymakers in urban rainwater management, especially in similar regions. Full article