Search Results (130)

The impacts of land use on stormwater runoff quality and Best Management Practices to mitigate these impacts have been investigated since the 1970s, yet challenges remain in providing a modeling approach that concomitantly considers contributions from different land use types. In densely developed urban areas, a buildup/washoff approach is often applied, while in rural areas, some type of erosion modeling is employed, as the processes of detachment, entrainment, and transport are fundamentally different. This study presents a coupled modeling approach within PCSWMM, integrating exponential buildup/washoff for impervious surfaces with the Modified Universal Soil Loss Equation (MUSLE) for pervious areas, including construction sites, to characterize water quality in the large mixed urban–rural Sparrovale catchment in Geelong, Australia. The watershed includes an innovative cascading system of 12 online NbS wetlands along one of the main tributaries, Armstrong Creek, to manage runoff quantity and quality, as well as 16 offline NbS wetlands that are tributary to the online system. A total of 78 samples for Total Suspended Solids (TSS), Total Phosphorus (TP), and Total Nitrogen (TN) were collected from six monitoring sites along Armstrong Creek during wet- and dry-weather events between May and July 2024 for model validation. The data were supplemented with six other catchment stormwater quality datasets collected during earlier studies, which provided an understanding of water quality status for the broader Geelong region. Results showed that average nutrient concentrations across all the sites ranged from 0.44 to 2.66 mg/L for TP and 0.69 to 5.7 mg/L for TN, spanning from within to above the ecological threshold ranges for eutrophication risk (TP: 0.042 to 1 mg/L, TN: 0.3 to 1.5 mg/L). In the study catchment, upstream wetlands reduced pollutant levels; however, downstream wetlands that received runoff from agriculture, residential areas, and, importantly, construction sites, showed a substantial increase in sediment and nutrient concentration. Water quality modeling revealed washoff parameters primarily influenced concentrations from established urban neighborhoods, whereas erosion parameters substantially impacted total pollutant loads for the larger system, demonstrating the importance of integrated modeling for capturing pollutant dynamics in heterogeneous, urbanizing catchments. The study results emphasize the need for spatially targeted management strategies to improve stormwater runoff quality and also show the potential for cascading wetlands to be an important element of the Nature-based Solution (NbS) runoff management system. Full article

Urban rivers provide vital ecosystem services, benefiting both nature and people, yet they are heavily impacted worldwide, exhibiting similar symptoms collectively known as the Urban Stream Syndrome (USS). This study assessed the ecological status of the Someșul Mic River, located in Cluj-Napoca, Romania’s second-largest and rapidly developing city, through the lens of benthic invertebrate communities, recognized for their strong bioindicator value. Six sites along the main river course, four adjacent sites on tributaries, and an artificial canal were analyzed. Our findings revealed the presence of USS at all sites; however, contrary to expectations, the mainstem sites showed higher water quality and greater taxonomic and functional diversity of zoobenthos. The primary drivers of this pattern were the proportion of coarse sediments and flow velocity, with river width playing a lesser role. Based on these results, eight mitigation strategies were proposed, aligned with the river ecosystem services. Their implementation could improve the ecological condition across the river, floodplain, and catchment levels, involving both scientists and the general public. Overall, the study provides a management-oriented framework for future river restoration initiatives in a growing city and a comparative reference for urban river assessments. Full article

Biocides, including fungicides and paraben preservatives, are widely used in medicine, agriculture and food industries, and are ubiquitous in aquatic environments, which will have adverse impacts on aquatic organisms. This study investigated the occurrence, distribution, ecological risks, and human health risks of 7 target biocides in Chao Lake, a large eutrophic urban lake, and its tributaries. Four biocides were detected, with total concentrations ranging from 186 ng/L to 853 ng/L. Carbendazim (CBD), fluconazole (FCZ), and methylparaben (MP) had detection frequencies of 100%, with mean concentrations of 234 ng/L, 35.3 ng/L, and 26.8 ng/L, respectively. Significant spatial heterogeneity was observed, with obviously elevated levels in the western region compared with the central and eastern regions. Strong correlations (p ≤ 0.01) were found between these three biocides, CBD, FCZ, and climbazole (CLI), and the following two environmental factors: total nitrogen and dissolved total nitrogen. Based on the risk quotient (RQ) evaluation, CBD was identified as a high-risk compound for aquatic organisms, particularly Daphnia magna, with RQ values exceeding 1 and reaching up to 7.42. CLI showed moderate risks at some sampling sites, while FCZ and MP posed no risk. Human health risk quotient (RQ_h) analysis revealed no significant health risks to different age groups, with the RQ_h values of biocides at all sampling sites in Chao Lake below 0.1. The ecological risks of CBD warrant even greater attention. Full article

Concrete-lined river channels are generally assumed to prevent groundwater exchange, functioning as inert conduits that isolate surface flow. Along the Upper Los Angeles River of Southern California, United States, however, field observations show that during dry summer months, groundwater seepage contributes nearly half of the dry-weather flow to a 9.5-km concrete-lined reach above Sepulveda Basin. This baseflow substantially modifies river chemistry, diluting some solutes while enriching others. To characterize these interactions, hydrochemical sampling was conducted in summer 2022, with additional selenium and tritium analyses from 2024 to 2025, covering tributaries, river sites, groundwater seeps, wastewater discharges, and tap water. Analyses included major ions, nutrients, selenium, and tritium. Upstream tributaries were highly saline (TDS ≈ 1670 mg/L; sulfate up to 980 mg/L; chloride ≈ 280 mg/L), whereas groundwater was moderately saline (TDS 990 to 1765 mg/L) but contained elevated nitrate-nitrogen (5.8 to 12.9 mg/L) and selenium (4.5–44.0 µg/L). Mixing analysis indicated that approximately 45% of the river’s dry-weather flow (~70.5 L/s) originated from groundwater, increasing riverine selenium above the 5 µg/L aquatic-life criterion. Downstream, where the concrete lining ends, wastewater inflows from the Donald C. Tillman Water Reclamation Plant reduced salinity but introduced additional nitrate-nitrogen. The results reveal a three-part sequence; saline tributary inputs at the headwaters, groundwater-driven nitrate and selenium enrichment within the lined reach, and effluent dilution downstream. These findings demonstrate that even concrete-lined channels can host active groundwater–surface water exchange, highlighting the need to incorporate such interactions in urban river management and channel design. Full article

Urbanization, characterized by rapid construction land expansion, has transformed natural landscapes and significantly altered river networks in emerging metropolitan areas. Understanding the historical and current conditions of river networks is crucial for policy-making in sustainable urban development planning. Based on the topographic maps and remote sensing images, this study employs a multi-metric framework to investigate river network variations in the Suzhou-Wuxi-Changzhou metropolitan area, a rapidly urbanized plain with high-density river networks in the Yangtze River Delta, China. The results indicate a significant decline in the quantity of rivers, with the average river density in built-up areas falling from 2.70 km·km⁻² in the 1960s to 1.95 km·km⁻² in the 2010s, along with notable variations in the river network’s structure, complexity and its storage and regulation capacity. Moreover, shifts in the structural characteristics of river networks reveal that urbanization has a weaker impact on main streams but plays a dominant role in altering tributaries. The analysis demonstrates the extensive burial and modification of rivers across the metropolitan plains. These findings underscore the essence of incorporating river network protection and restoration into sustainable urban planning, providing insights for water resource management and resilient city development in rapidly urbanizing regions. Full article

Improved understanding of the behaviour of microplastics in freshwater systems is important as rivers are major conduits for the transport of particles from land to sea. This study investigated microplastics in two tributaries of the River Clyde, Scotland, UK, that flow through rural, suburban and urban areas. Surface water and sediment were obtained from 25 locations in the Black Cart Water and White Cart Water. Microplastics were isolated and characterized by digital microscopy and ATR-FTIR spectroscopy. Particles were found in four water samples, all from the White Cart. Sediment analysis revealed microplastic abundance ranging from 300 to 600 items/kg in the Black Cart and 33.3 to 567 items/kg in the White Cart. Fragments were the most common particle type and white/transparent the most common particle colour. The most common polymers in the Black Cart were PE > PET > PS > PVC > PTFE and in the White Cart PE > PP > PTFE > PET > PA. Identification of some microplastics was challenging because their FTIR spectra did not correspond well to reference spectra of pure polymers. Although the polymer hazard index at some locations was high due to the presence of particles composed of PVC and PA, the ecological risk from microplastics in the Cart river system was generally low. Full article

Despite increasing concerns over recurrent phosphorus (P) pollution, the Ju River—a small tributary of the Yangtze River—has received limited scientific attention. To correct this, the present study integrates field-based observations with the Hydrological Simulation Program—FORTRAN (HSPF) model to comprehensively assess the conjunct effects of urban expansion and changing precipitation patterns on watershed hydrology and phosphorus dynamics at the small-catchment scale. A total of five urban expansion scenarios and three precipitation enhancement scenarios were simulated to capture both seasonal and event-driven variations in daily discharge and total phosphorus (TP) concentrations. The model was calibrated and validated using in situ water quality data, ensuring high reliability of the simulations. The results indicate that agricultural non-point sources are the primary contributor to total phosphorus (TP) loads. During the overlapping period of intensive farming and heavy rainfall (June–July), TP concentrations more than doubled compared to other months, with these two months accounting for over 70% of the annual TP load. Urban expansion significantly amplified hydrological extremes, increasing peak discharge by up to 224% under extreme rainfall, thereby intensifying flood risks. Although increased precipitation diluted TP concentrations, it simultaneously accelerated overall phosphorus export. This study offers a novel modeling–monitoring framework tailored for small watersheds and provides critical insights into how land use transitions and climate change jointly reshape nutrient cycling. The findings support the development of targeted, scenario-based strategies to mitigate eutrophication risks in vulnerable river systems. Full article

Stream temperatures are expected to increase with warming air temperatures, yet the extent and aquatic health impacts vary significantly across heterogeneous landscapes. This study was conducted in a 3360-ha multi-land-use watershed in the Pacific Northwest region of the USA to assess and compare the driving factors for stream temperature heating, cooling, and cool-water refugia along a 12-km mainstem stream longitudinal profile. Study objectives were to (1) determine yearlong stream temperature variability along the entire stream longitudinal profile, and (2) assess stream-environment relationships influencing stream temperature dynamics across forest, agriculture, and urban landscapes within the watershed. Stream and riparian air temperatures, solar radiation, shade, and related stream-riparian characteristics were measured over six years at 21 stations to determine changes, along the longitudinal profile, of thermal sensitivity, maximum and minimum stream temperatures, and correlation between solar radiation and temperature increases, and potential causal factors associated with these changes. Solar radiation was a primary heating factor for an exposed agricultural land use reach with 57% effective shade, while southern stream aspects and incoming tributary conditions were primary factors for forested reaches with greater than 84% effective shade. Potential primary cooling factors were streambank height, groundwater inflows, and hyporheic exchange in an urban reach with moderate effective shade (79%) and forest riparian width (16 m). Combining watershed-scale analysis with on-site stream-environmental data collection helps assess primary temperature heating factors, such as solar radiation and shade, and potential cooling factors, such as groundwater and cool tributary inflows, as conditions change along the longitudinal profile. Full article

Global climate change, combined with the construction of impermeable urban elements, tends to increase runoff, which might cause flooding and reduce groundwater recharge. Moreover, the first flash of these areas might accumulate pollutants that might deteriorate groundwater quality. A digital elevation model (DEM) describes urban landscapes by representing the watershed relief at any given location. While, in concept, finer DEMs and land use classification (LUC) are yielding better hydrological models, it is suggested that over-accuracy overestimates minor tributaries that might be redundant. Optimal DEM resolution with integrated spectral and feature-based LUC was found to reflect the hydrological network’s significant tributaries. To cope with the karstic urban watershed complexity, ModClark Transform and SCS Curve Number methods were integrated over a GIS-HEC-HMS platform to a nominal urban watershed sub-basin analysis procedure, allowing for detailed urban runoff modeling. This precise urban karstic terrain modeling procedure can predict runoff volume and discharge in urban, mountainous karstic watersheds, and may be used for water-sensitive design or in such cities to control runoff and prevent its negative impacts. Full article

Antibiotic resistance (AR) in environmental Escherichia coli represents a growing public health challenge. This study evaluated the prevalence of AR among E. coli isolates recovered from surface water bodies within the Ameca River basin in Jalisco, Mexico, and examined associations with anthropogenic influence and seasonal variation. Over a 1-year period, water samples were collected monthly from 16 sites, including tributaries, wetlands, and main river channels with differing degrees of urban impact. E. coli isolates were confirmed by malB gene PCR and tested for susceptibility to six antibiotics using the Kirby–Bauer disk diffusion method. High resistance frequencies were observed for ampicillin (93.9%), tetracycline (92.4%), and streptomycin (89.6%), while gentamicin exhibited the lowest resistance rate (48.1%). Resistance prevalence was significantly higher at sites adjacent to urban settlements and during the rainy season (p < 0.05). These findings underscore the influence of land use and seasonal dynamics on AR dissemination in aquatic environments and highlight the need for improved wastewater management strategies to mitigate the spread of resistant bacteria. Full article

Phewa Lake, Nepal’s second-largest natural lake, is under increasing ecological stress due to sedimentation, shoreline encroachment, and water quality decline driven by rapid urban growth, fragile mountainous catchments, and changing climate patterns. This study employs an integrated approach combining sediment yield estimation from its catchment using RUSLE, shoreline encroachment analysis via satellite imagery and historical records, and identification of pollution sources and socio-economic factors through field surveys and community consultations. The results show that steep, sparsely vegetated slopes are the primary sediment sources, with Harpan Khola (a tributary of Phewa Lake) contributing over 80% of the estimated 339,118 tons of annual sediment inflow. From 1962 to 2024, the lake has lost approximately 5.62 sq. km of surface area, primarily due to a combination of sediment deposition and human encroachment. Pollution from untreated sewage, urban runoff, and invasive aquatic weeds further degrades water quality and threatens biodiversity. Based on the findings, this study proposes a way forward to mitigate sedimentation, encroachment, and pollution, along with a sustainable revitalization plan. The approach of this study, along with the proposed sustainability measures, can be replicated in other lake systems within Nepal and in similar watersheds elsewhere. Full article

River pollution is a major issue in China’s urbanization process. Understanding the effects of river morphology and constructed wetlands on the self-purification capacity is crucial for water quality improvement. This study takes the Shiwuli River, a main tributary of Chaohu Lake, as an example. By monitoring the concentration changes of five water quality indicators—total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH₃-N), chemical oxygen demand (COD), and dissolved oxygen (DO)—in the river section for the years 2017 and 2024, we conducted a comparative analysis of the relationship between river morphology and self-purification capacity, as well as influencing factors. The results show that meandering rivers possess self-purification capabilities under natural conditions. There is a positive correlation between river sinuosity and the reduction rates of TP, TN, NH₃-N, and COD, as well as the increase rate of DO—the greater the sinuosity, the stronger the purification capacity. Wetlands enhance both the self-purification capacity and the purification rate of river channels, reducing the required sinuosity for effective self-purification from 1.49 to 1.30. This study also discusses the mechanisms by which meandering rivers influence water self-purification, and proposes that increasing river sinuosity and constructing wetlands can enhance the self-purification capacity. This measure will increase the length and width of the river, prolong the purification time, improve the DO level, and enhance the exchange between the riverbed and groundwater. The findings of this study can provide a reference for river restoration and management in the context of urbanization. Full article

As a major tributary of the Yellow River, the Yiluo River holds vital importance for regional water resource management and ecological sustainability. In this study, the SWAT (version 2012) and PLUS models were used in combination to simulate the hydrological responses of the basin and to analyze how land use changes have influenced runoff dynamics over time. During the calibration and validation periods, the Nash–Sutcliffe efficiency coefficient (NS) and coefficient of determination (R²) for the SWAT model both exceeded 0.8, while the Kappa coefficient for the PLUS model indicated an overall accuracy of 0.91, confirming the applicability of both models to the Yiluo River Basin. However, despite strong annual performance, potential monthly or seasonal simulation uncertainties should be acknowledged and warrant further analysis. From 2000 to 2020, the areas of forest land, water, urban land, and unused land in the Yiluo River Basin increased by 795.15 km², 29.33 km², 573.67 km², and 0.25 km², respectively, while cultivated land and grassland decreased by 814.50 km² and 583.89 km². The spatial distribution of the annual average runoff depth generally exhibited a pattern of “higher in the upstream and lower in the downstream”. An increase in the forestland and grassland areas was found to suppress runoff generation, whereas the expansion of urban land promoted runoff production. Implementing water-sensitive land use strategies—such as expanding forest cover and conserving grasslands—is crucial for reducing the negative hydrological impacts of urban land expansion. Such measures can improve runoff regulation, enhance groundwater recharge, and support the sustainable management of water resources within the basin. Assuming climate conditions remain constant, land use in the Yiluo River Basin in 2025 and 2030 is expected to remain dominated by cultivated land and forestland. Under this scenario, the annual average runoff is projected to increase by 0.42% and 0.51% compared to in 2020, respectively. Full article

This study evaluates the water quality of the Tamiš River, a tributary of the Danube, at the Jaša Tomić and Pančevo hydrological stations from 2011 to 2016 and from 2018 to 2022, using the Water Pollution Index (WPI) and seasonal analysis. The analysis revealed elevated nitrite and orthophosphate concentrations at both stations, with Pančevo exhibiting extreme microbial contamination in 2015, attributed to urban runoff, agricultural activities, and inadequate wastewater treatment. Seasonal results indicate that while spring conditions align with Class I water standards, summer presents critical risks, especially at Pančevo, where the highest WPI value (26.47 in 2015) was recorded. Autumn shows stabilization, though sporadic WPI peaks reflect the impact of nutrient runoff. Winter conditions are marked by stability, with favorable dissolved oxygen levels but occasional exceedances in heavy metals, particularly at Jaša Tomić. Increased concentrations of suspended solids and heavy metals at Jaša Tomić emphasize diverse pollution sources, including industrial discharges and soil erosion. These findings underscore the necessity of integrated water management strategies, such as wastewater treatment upgrades and sustainable agricultural practices, to mitigate pollution. Protecting the Tamiš River is crucial for supporting biodiversity, safeguarding public health, and ensuring sustainable use of this vital Danube tributary. Full article

Historically, the Wei River has served as part of the Yongji Canal section of the Grand Canal, playing a crucial role in connecting northern and southern China. However, with the acceleration of urbanization in China, issues such as excessive land development and ecological landscape fragmentation have emerged. Exploring the mechanisms of landscape fragmentation evolution in the Wei River basin and proposing optimization strategies is of significant importance for land use and ecological stability within small- to medium-sized river basins. This study selected land use data from the Weihe River basin between 2000 and 2020, using landscape pattern indices to analyze the trend of landscape fragmentation. The principal component analysis (PCA) and geographical detector methods were employed to explore the distribution characteristics and driving factors of landscape fragmentation. The research results indicate that: (1) The degree of landscape fragmentation in the Wei River basin has progressively intensified over time. The edge density index (ED), the landscape division index (DIVISION), the landscape shape index (LSI), and the Shannon diversity index (SHDI) have increased annually, while the contagion index (CONTAG) and area-weighted mean patch size (Area_AM) have continuously decreased; (2) Landscape fragmentation in the Wei River basin is characterized by stable changes in the source and tributary fragmentation areas, a concentrated distribution of fragmentation in the tributaries, and a significant increase in fragmentation in the main stream; (3) The analysis using the geographic detector method indicates that vegetation coverage (FVC), human activity intensity (HAI), and land use/land cover change (LUCC) are the main driving factors of landscape fragmentation in the Wei River basin. The findings explore the mechanisms of landscape fragmentation in the basin and provide a reference for land use planning and ecological restoration in the region. Full article