Historic cities face a dual challenge of managing waterlogging risks while adhering to strict preservation constraints. Traditional drainage upgrades often require extensive excavation, threatening cultural heritage. This study establishes a quantitative assessment framework for the historic urban district of City B using a 1D-2D-coupled hydrodynamic model (InfoWorks ICM). The model was calibrated using continuous monitoring data, achieving a Nash–Sutcliffe Efficiency (NSE) of 0.91. Its spatial accuracy was subsequently validated against historical waterlogging records, showing a strong consistency between simulated flood-prone areas and observed flood locations. We simulated waterlogging distribution under rainfall events with return periods of 0.5 to 5 years. Results reveal two key deficiencies in the current drainage system under a 0.5-year return period storm event. Firstly, 75.3% of the pipe segments are hydraulically overloaded, failing to meet the design standard. Secondly, this widespread network overload contributes to surface waterlogging, with 9.58 ha (1.80% of the total area) being waterlogged. We evaluated three strategies: Low Impact Development (LID), underground storage tanks, and intercepting sewers. A hybrid grey-green infrastructure (HGGI) system was proposed, integrating source reduction and terminal storage. The HGGI system reduced waterlogged areas by 83.58% (0.5-year event) and 64.87% (5-year event), outperforming single measures. Crucially, this hybrid system achieves minimal intervention in historic street patterns through trenchless construction for intercepting sewers, decentralized LID layout and underground storage tanks, avoiding large-scale road excavation while enhancing flood resilience. This study demonstrates that hybrid strategies can effectively balance flood resilience with environmental and cultural preservation in high-density historic districts.

Emerging insights into low impact development (LID) strategy for urban flood resilience under climate change

Rapid urbanization increases rainfall runoff and the discharge of non-point source pollutants. These outflows and pollutants have mainly been reduced through detention in reservoirs, diversion to sewage treatment plants, or the use of non-point pollution reduction devices before entering rivers. However, in recent years, efforts have focused on reducing them at the source. Representative concepts for this approach are Low Impact Development (LID) and Green Infrastructure (GI). Facilities for this include Porous Asphalt Pavement (PA), Porous Asphalt Pavement (PB), Infiltration Trench (IT), and Tree Box Filter (TB), and various other forms have been proposed, such as rooftop greening and storage-type green spaces. These facilities can be applied to existing cities or new development sites, but they can be implemented more efficiently in newly developed sites. In this study, an optimization search was conducted to achieve maximum reduction effect and minimum cost by selecting optimal LID facilities using the Harmony Search (HS) algorithm for new complexes. As a result of the analysis, it was possible to select the type, size, and location of facility appropriate for optimal efficiency and cost. According to the technique presented in this study, it is expected to be useful in practice, as it allows the selection of optimal solutions for very complex and diverse conditions.

Conventional centralized drainage systems exacerbate urban flooding, pollution, and water stress. Low-impact development (LID) is a decentralized alternative; however, its multifunctional benefits, which go beyond the control of stormwater, are often undervalued in planning. This study fills this gap by developing an integrated benefit valuation framework to systematically quantify and estimate the economic value of the co-benefits of five widely implemented LID facilities (vegetated swale, green roof, in-filtration ditch, infiltration trench, and permeable pavement) in Seoul, South Korea. The framework combines annual benefits in four key sectors: water management (runoff reduction), energy savings (building cooling/heating demands), air quality (pollutant deposition and avoided emissions) and climate change (carbon sequestration and mitigation). Applying a transparent, localized spreadsheet model, the results indicate significant multifunctional value for LID systems. While water management provides the primary benefit, there is substantial added value in energy, air quality, and climate co-benefits. In the case of green roofs, such ancillary benefits can exceed hydrological values. The analysis further reveals a consistent scale-benefit relationship and a clear trade-off between the magnitude of benefits and the cost of implementation. This provides evidence of the need for context-sensitive, portfolio-based LID planning. The proposed framework is a practical decision support tool for urban planners and policymakers to consider LID not only as a stormwater solution but also as multifunctional green infrastructure that simultaneously promotes urban water security, energy efficiency, environmental quality, and climate resilience.

The essential function of low impact development facilities in mitigating urban flood disasters: approach for multi-source data fusion simulation

Integrating recycled pervious blocks into urban drainage systems: a PCSWMM-based assessment of low-impact development potential

Climate change, together with rapid and frequently unplanned urban expansion, is placing increasing pressure on stormwater drainage systems in inter-Andean cities such as Huancayo (Junín, Peru). This study uses the Storm Water Management Model (SWMM) to make a prediction about how Huancayo's stormwater network will work now and in the future based on climate models. Local hydrometeorological records and stormwater infrastructure data are combined and collected to model runoff response, peak discharge, ponded volume, and network overload. Simulations show that under normal conditions for 10 and 100-year return periods, the system has limited capacity. Peak outflows reach about 78 to 121 m³/s, ponded volumes rise to about 62,000 to 145,000 m³, and node surcharge is widespread. In a 2070 projection using RCP 8.5, peak discharge and ponded volume rise by about 21% and 37%, respectively, compared to the baseline. A hybrid green–gray adaptation package that includes detention tanks, Low-Impact Development (LID) practices, collector enlargement, and monitoring support cuts peak flows and ponded volumes by 30% to 46% in baseline conditions and by about 29% to 33% in the future scenario. The findings underscore that predictive hydraulic modeling can facilitate pragmatic adaptation planning and enhance flood resilience in elevated urban catchments subject to climatic variability.

Risk-Informed Optimization of Low-Impact Development Strategies Using Slime Mould and NSGA-III Algorithms for Heavy Metal Mitigation in Urban Runoff

ABSTRACT Economic assessments of low-impact development (LID) in the Philippines are limited to evaluating primary benefits related to hydrologic performance in micro-scale applications due to limited data and tools for quantifying multiple secondary benefits. This study addressed this through a holistic cost-benefit analysis of rainwater harvesting (RH), green roof (GR), bioretention (BR), and permeable pavement (PP) in residential and industrial settings at the sub-catchment scale. A method to monetize flood damage reduction was developed using a coupled one- and two-dimensional (1D–2D) flood model. Multiple co-benefits, including energy savings, CO2 reduction, air pollutant removal, water savings, and groundwater recharge, were quantified using various benefit transfer methods. Comparisons with gray infrastructure were made using cost, net benefits, benefit-cost ratio, and payback period as decision criteria. The results showed that gray infrastructure offered higher flood damage reduction (residential, 14–91%; industrial, 90–1,407%). However, it was possible to combine LID to achieve better results than gray infrastructure (e.g., residential RH + GR, 24%). Combined alternatives produced higher net benefits (e.g., residential Gray + RH, 17.9 million; industrial Gray + PP, 67.1 million), while individual measures tend to have higher cost-benefit ratios (e.g., residential RH, 1.73; industrial Gray, 1.39). Inclusion of co-benefits significantly improved LID feasibility; hence, proper accounting is needed to increase LID adoption.

Investment in sewage treatment significantly reduces greenhouse gas emissions of urban rivers.

Optimized Configuration of Urban Low Impact Development Based on MIKE + and Life Cycle Cost Analysis

Urban expansion, together with an increasing frequency of extreme rainfall, has significantly raised both the occurrence and the economic losses of urban flooding. Green infrastructure (GI), the backbone of low-impact development (LID), is widely regarded as capable of reducing surface runoff, delaying peak discharge, and strengthening the resilience of urban drainage. Yet a unified and transferable framework for quantifying, spatiotemporally linking, and scaling the flood-mitigation effects of “green space–flood” interactions is still lacking. This paper reviews recent progress in the use of remote-sensing techniques for urban flood monitoring and in the coupled analysis between these observations and the spatial configuration of GI. We first outline the key optical and SAR approaches for mapping water bodies and inundated areas—NDWI/MNDWI, threshold-based segmentation, and deep-learning semantic segmentation—and then summarize the indices and metrics commonly used to identify and characterize urban green space (NDVI, EVI, landscape-pattern indices, connectivity, etc.). We detail how these green-space layers are overlaid with flood extents, examined through buffer statistics, and synthesized into a Green-space Flood-Mitigation Index (GFMI). Next, we dissect three persistent challenges: scale mismatch, SAR misclassification in dense built-up areas, and the difficulty of attributing flood reduction to GI alone. Finally, we advocate an integrated “remote sensing–3-D urban/drainage model–machine learning” approach, emphasizing the need to feed remote-sensing-derived metrics directly into urban green-space planning, sponge-city design, and coupled watershed–urban management.

Accelerated urban growth results in soil impermeabilization, intensifying problems such as floods and urban heat islands (UHIs) formation. Pervious concrete pavement (PCP) is a strategy used to mitigate these problems, with the capacity to regulate stormwater runoff and its low thermal conductivity. However, clogging, caused by the infiltration of sediments, obstructs the pores of the PCP, compromising its hydraulic and thermal performance. This study investigates the effects of clogging on PCP overlay, with a focus on thermal behavior and conductivity. Initially, air temperature and humidity were evaluated to understand their influence on the surface temperatures of the clean PCP. When comparing the unclogged and clogged PCPs, the unclogged PCP showed surface temperatures on average 1.25 °C higher than the clogged ones under solar exposure. The thermal conductivity analysis revealed the impact of clogging with sand, which has a conductivity 85.7% higher than air. The results indicate that, although clogging impairs hydraulic performance, it improves thermal performance. These findings suggest that the balance between hydraulic and thermal behaviors must be evaluated when managing low-impact development structures.

Rain gardens represent critical Low Impact Development (LID) infrastructure enhances urban resilience by reducing surface runoff and mitigating pollutants. However, their design in high-altitude Andean cities presents unique challenges due to extreme environmental stressors, including cold temperatures, high solar radiation, and drought. The Authors compared three statistical distributions (Gumbel, Log-Pearson Type III, and Generalized Extreme Value) using L-moments estimation to determine design storm intensities for multiple return periods. The Gumbel distribution demonstrated an optimal fit, yielding design precipitation values of 43. 0 mm (2-year), 56. 0 mm (5-year), 64. 6 mm (10-year), and 75. 4 mm (25-year) for 24-hour-duration storms. The design achieves 0.90 m3 storage per unit. 50 m × 1. 00 m internal dimensions), the proposed design achieves a storage volume of 0. 90 m3 per unit with a safety factor of 1. 74 for the recommended 10-year design storm. The substrate composition follows proven Andean bioretention systems, utilizing sand-silt-clay mixtures (60-30-10%) with a depth of 0. 60-0. 80 m to maintain hydraulic conductivity between 13 and 150 mm/hr, while supporting native vegetation adapted to high-altitude stress conditions. This framework provides actionable engineering specifications for climate-resilient green infrastructure in Andean Mountain cities while establishing a methodology for adaptive design under data-limited conditions.

Stormwater washes microplastics deposited on road dust or floating in the air into urban pipeline networks and then into rivers， lakes， and oceans， which is a direct threat to ecosystems and human health. Therefore， there is an urgent need to implement control measures for microplastics in runoff. As one of the low-impact development strategies， bioretention systems can remove various pollutants， including microplastics， from runoff through natural processes such as adsorption and filtration by soil media， absorption by plants， and biodegradation by microorganisms， demonstrating effective microplastic management. However， due to their large specific surface area and resistance to degradation， most microplastics tend to accumulate within these systems， easily forming composite pollution with other contaminants， which hinders the removal of nutrients by bioretention systems. Based on a comprehensive analysis of domestic and international research on bioretention systems， this study summarizes the microplastic removal processes within bioretention systems and further explores the impact of microplastic accumulation on the nutrient treatment capabilities of these systems. The results indicated that microplastic accumulation altered the physicochemical properties of the soil media in bioretention systems， impeded plant growth and development， and inhibited the abundance and activity of relevant enzymes and microorganisms involved in nutrient processing. Notably， the removal of dissolved nitrogen， which primarily occurs through biodegradation processes in these systems， was significantly affected. The findings of this study provide scientific insights for microplastic management and the optimization of bioretention system performance. It also highlights future research directions， including the microplastic removal method， microplastic ageing mechanism， system numerical simulation， and so on.

Low impact development (LID) systems effectively reduce stormwater runoff and improve water quality. In addition, their potential contributions to carbon sequestration and climate change adaptation have attracted growing research attention. This study investigated the influence of biochar content on the performance of bioretention cells. A series of experiments was conducted to evaluate eight key indicators: saturated hydraulic conductivity (Ksat), water holding capacity, removal efficiencies for ammonium nitrogen (NH4-N), nitrate nitrogen (NO₃-N), phosphate (PO43--P), and chemical oxygen demand (COD); CO2 sequestration flux; and soil organic carbon content. The results indicate that biochar amendments significantly improve the functionality of LID systems. Furthermore, the addition of 2.5% biochar effectively enhances soil hydrological properties, creating favorable conditions for plant growth. The addition of 5% biochar results in optimal pollutant removal and water purification, thus serving as a well-balanced and efficient treatment strategy. Moreover, the addition of 10% biochar results in optimal carbon sequestration, demonstrating the role of biochar in strengthening soil carbon sinks. However, excessive biochar content may affect microbial activity and nutrient pathways, potentially leading to reductions in NO3-N and COD removal efficiencies. This study provides practical guidance for optimizing biochar use in LID systems to support stormwater management, water quality improvement, and long-term climate mitigation through soil-based carbon storage.

Polycyclic aromatic hydrocarbons (PAHs) are detrimental to human health and the environment as a hazardous persistent organic pollutant of environmental concern. Research is emerging on the occurrence, form, migration characteristics and removal of PAHs from runoff stormwater by bioretention cells. This review analyses the sources of PAHs, the characteristics of their concentration distribution and their migration pattern in stormwater runoff. The mechanism of PAH removal by bioretention cells, the purification effects of different fillers and their influencing factors, and the accumulation characteristics of PAHs in bioretention cells are analysed, and the influence mechanism of PAH accumulation on the performance of bioretention cells is summarised. It is noteworthy that the typical concentration range of polycyclic aromatic hydrocarbons (PAHs) in urban stormwater runoff is 0.65-13.4 µg L-1. The average PAH concentrations in surface runoff vary across different functional zones, with levels in industrial and commercial areas generally being significantly higher than those in residential areas, green spaces, and other functional zones. Studies have shown that the overall removal efficiency of PAHs by bioretention cells can consistently exceed 80%, demonstrating their significant potential for pollution control. Based on existing research progress, this review further proposes that future efforts should focus on the following research directions: (1) induction of the decomposition of PAHs accumulated in bioretention cells into degradable products; (2) search for more effective fillers to improve their removal efficiency; (3) effects of PAH contamination on microbial functions in the filler of bioretention cells; and (4) synergistic effects of PAHs with other pollutants on bioretention cells. This review evaluates the actual PAH removal performance of bioretention facilities, which holds significant scientific and practical value for optimizing the design of low-impact development facilities and ensuring the safety of the urban water environment.

The effects of combined structural and nonstructural measures in reducing urban flood damage in the Taehwa District, Jung-gu, Ulsan Metropolitan City, South Korea, were analyzed using the storm water management model (SWMM). Sixteen scenarios combining structural measures, such as drainage pump stations and high-altitude drainage tunnels, with nonstructural measures, including low impact development (LID) facilities (planter box, bioretention, permeable pavement, vegetative swale, infiltration channel, infiltration chamber) and detention facilities, were simulated using rainfall data from Typhoon Chaba in 2016. Analysis results revealed that scenarios incorporating structural measures significantly reduced inundation area and water levels, with some combinations reducing the flooded area by more than 50％. In contrast, the flood-reduction effects of LID measures alone were minimal, demonstrating virtually no impact during the extreme rainfall event. LID facilities contributed to improving water circulation by absorbing the initial rainfall into the subsurface. This study concluded that structural measures, such as drainage pump stations and high-altitude drainage tunnels, are essential for large-scale flood response, while the concurrent implementation of non-structural measures, such as LID facilities and detention basins, can provide additional flood reduction and water circulation improvement effects.

Background and objective: Rapid urbanization in South Korea has intensified environmental concerns such as surface sealing, urban heat accumulation, and ecological degradation. Green Infrastructure (GI) has been adopted as a spatial strategy to address these issues. However, existing empirical studies remain fragmented by spatial scale and methodology. This study conducts a scoping review to synthesize research trends and identify how GI functions are examined across diverse analytical contexts.Methods: Using identification, screening, and inclusion procedures, 31 empirical studies were selected from 4,294 records retrieved from the Research Information Sharing Service (RISS) database. The selected studies were classified according to research context, including spatial level, types of GI elements, and methodological approach, and were subsequently analyzed to identify thematic patterns.Results: GI research was concentrated in metropolitan regions, where data availability and environmental pressures are relatively high. The analytical scale was closely associated with the types of GI elements examined: large parks and wetlands at the metropolitan level, low impact development (LID) facilities and river corridors at the municipal level, and gardens and biotopes at the sub-municipal level. Accordingly, functional themes also varied by spatial scale ranging from hydrologic regulation and climatic mitigation to particulate matter reduction and user-centered experiences. Methodologically, GIS-based analyses were used to examine spatial distribution; hydrological modeling assessed stormwater runoff and infiltration processes; field monitoring documented operational changes; indicator-based analyses structured environmental performance metrics; and sociocultural approaches addressed user perceptions and accessibility.Conclusion: Empirical studies on GI in South Korea have primarily focused on environmental aspects, while social and economic dimensions have been comparatively less examined. The strong concentration of study sites in the Seoul metropolitan area indicates limited regional representativeness. To more comprehensively capture the diverse functions and context-specific characteristics of GI, future research should incorporate broader spatial coverage and adopt multi-method.

Climate change-driven increases in extreme rainfall disrupt the urban hydrological cycle in highly impervious settings and overload drainage systems, thereby intensifying flooding. Low Impact Development is therefore increasingly being adopted; among its measures, permeable pavements installed on parking lots and roadways can facilitate stormwater storage, infiltration, and delayed discharge. However, hydrological evaluations of permeable pavements integrated with drainage infrastructure remain limited. This study experimentally compares two systems under successive high-intensity storms: Pavement A, a permeable pavement over an impermeable subgrade with no subbase-to-catch-basin drainage, and Pavement B, a permeable pavement with a subbase that provides lateral drainage to a catch basin. Compared with Pavement A, Pavement B achieved greater event-scale runoff reduction and peak-flow attenuation and, after rainfall ceased, sustained long-duration delayed discharge that promoted pore-space recovery and more stable drainage performance. These findings indicate that the integration of permeable pavement with catchment and basin systems offers both short-term (runoff and peak mitigation) and long-term hydrological benefits, supporting its application in improving urban water-cycle resilience.