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The severe drought in California (2012-2016) generated significant public and government concern. State and local watering regulations were enacted to reduce residential and commercial water-use during the droughts. This study presents a comparison of residential runoff volumes before and after local landscape irrigation regulations were enacted during the droughts of 2008 and 2012-2016. Each sampling site (Folsom 1 and Folsom 2) was a storm drain outfall that drained a low-density residential catchment in the City of Folsom. Dry season runoff measured at the sampling sites represents neighborhood outdoor water waste, mainly from landscape irrigation. During the drought of 2012-2016, median runoff flows were significantly reduced after local landscape irrigation regulations were enacted. The daily runoff pattern was also highly influenced by regulation, with reductions of daily peak runoff flows on 4-5 days in a week after watering regulations were enacted. The number of peak flow events in the daily runoff pattern were reduced during this period. In addition, a significant reduction in mean runoff volume occurred. Based on these results, the watering regulations enacted by the City of Folsom had a positive effect on reducing urban runoff from residential neighborhoods during the dry season. As the results are from monitoring sites in a relatively small geographical area, further work should evaluate reductions in irrigation runoff from other California locations to determine if this is a localized phenomenon.

The productivity of olive in the northwestern coastal zone of Egypt is significantly constrained by drought and low organic matter in the soil. This study addresses these challenges by exploring the synergistic effects of olive mill wastes (OMW) application and micro-catchment water harvesting techniques on soil properties, runoff, moisture storage, and rainwater harvesting efficiency. Field experiments were conducted over two winter seasons, employing different micro-catchment structures (semi-circular and triangular bunds) and OMW applications. The results revealed that the integration of semi-circular bunds with OMW application (T4) substantially increased rainwater harvesting efficiency by 67.7% and 46.4% in the first and second seasons, respectively. Additionally, T4 and T5 exhibited reduced runoff by 47.8% and 41.3% in the first season and 49.4% and 38.9% in the second season, respectively. T4 significantly enhanced soil organic matter, soil macronutrients (N, P, and K), and micronutrients (Fe, Mn, Zn, and Cu) compared to the control (T1). The study highlights the effectiveness of T4 in improving soil moisture, reducing soil erosion, and enhancing soil fertility. This integrated approach involving OMW application within a semi-circular bund as a water harvesting system proves to be a promising strategy for sustainable olive cultivation in arid conditions. [ABSTRACT FROM AUTHOR]

Estuaries and coasts runoff plays a crucial role in the dynamics of the ocean system. However, the current emphasis on synthetic aperture radar (SAR) retrieved current velocities has been on studying strong boundary currents and large-scale ocean circulation, resulting in relatively limited observational research on estuarine current velocities. This study aims to observe the current velocities in the Yangtze River estuary area using Sentinel-1A SAR data. The findings indicate a high agreement between the current velocities retrieved by Sentinel-1A and those observed at hydrographic stations, showcasing the characteristics of current velocity distribution associated with seafloor topography. This highlights the significant potential of SAR in observing estuarine current velocities, contributing to the analysis of benthic topography and the statistics of river runoff. [ABSTRACT FROM AUTHOR]

The Thoubal river catchment (TRB) and Iril river catchment (IRB), which are two major adjoining subbasins of the Manipur river basin in India, were selected for this study. A GIS-based semi-distributed hydrological model soil and water assessment tool (SWAT) was used to derive the hydroclimatic parameters such as surface run-off, evapotranspiration. The present study aims to calibrate and validate the SWAT model using streamflow and satellite soil moisture data, as well as to examine the hydroclimatological responses in the two adjacent basins, and compare the relative changes in treating the Iril-Thoubal river basin jointly and as two separate entities. The model was calibrated and validated using the SUFI-2 tool. During calibration and validation, both IRB and TRB showed good model performance. This study shows that in a poorly gauged river basin with scarce data, remotely sensed soil moisture data may be effectively applied for the calibration and validation of hydrological models. The novel aspect of this study is the efficient calibration and validation of a hydroclimatic model for subtropical river sub-basins with limited hydrological ground data reinforced with open-source satellite-derived soil moisture datasets. [ABSTRACT FROM AUTHOR]

Previous studies have proven the efficiency of LID practices in mitigating surface runoff in urban watersheds; however, the impact of their placement strategy over the urban drainage system, under continuous temporal hydrological simulation, has not been explored yet. This study simulated, under continuous time scale, five LID practices and four LID placement strategies (downstream, center, upstream and uniformly) on the drainage system of the Universidade Federal de Lavras urban area, in the state of Minas Gerais, Brazil. Under the conditions analyzed, it was found that there were no significant statistical differences between the efficiency of the different LID practices, individually or combined, within the same placement strategy. The uniform placement strategy proved to be more efficient, but in soils with higher Ksat values, other strategies showed better results. Therefore, it was found that soil Ksat is a parameter that should be carefully analyzed for LID practices implementation. [ABSTRACT FROM AUTHOR]

Valid simulation results from global hydrological models (GHMs), such as WaterGAP3, are essential for detecting hotspots or studying patterns in climate change impacts. However, the lack of worldwide monitoring data makes it challenging to adapt GHM parameters to enable such valid simulations globally. Therefore, regionalization is necessary to estimate parameters in ungauged basins. This study presents the results of regionalization methods for the first time applied to the GHM WaterGAP3. It aims to provide insights into (1) selecting a suitable regionalization method for a GHM and (2) evaluating its impact on runoff simulation. In this study, four new regionalization methods have been identified as appropriate for WaterGAP3. These methods span the full spectrum of methodologies, i.e., regression-based methods, physical similarity, and spatial proximity, using traditional and machine-learning-based approaches. Moreover, the methods differ in the descriptors used to achieve optimal results, although all utilize climatic and physiographic descriptors. This demonstrates (1) that different methods use descriptor sets with varying efficiency and (2) that combining climatic and physiographic descriptors is optimal for regionalizing worldwide basins. Additionally, our research indicates that regionalization leads to spatially and temporally varying uncertainty in ungauged regions. For example, regionalization highly affects southern South America, leading to high uncertainties in the flood simulation of the Río Deseado. The local impact of regionalization propagates through the water system, also affecting global estimates, as evidenced by a spread of 1500 km 3 yr -1 across an ensemble of five regionalization methods in simulated global runoff to the ocean. This discrepancy is even more pronounced when using a regionalization method deemed unsuitable for WaterGAP3, resulting in a spread of 4208 km 3 yr -1. This significant increase highlights the importance of carefully choosing regionalization methods. Further research is needed to enhance the predictor selection and the understanding of the robustness of the methods on a global scale. [ABSTRACT FROM AUTHOR]

Snowmelt erosion and rainfall erosion are important components of soil erosion in Northeast China. Studying how snowmelt and rainfall affect runoff and sediment yield is essential to control soil erosion in this region. Based on the soil and water loss observation data in small watershed during snowmelt and rainfall periods, snowmelt and rainfall erosion processes were studied. The runoff–sediment relationship was analyzed. The results indicate that 13 snowmelt runoff events and 14 rainfall runoff events were recorded. During the snowmelt period, runoff depth (RD) and sediment yield (SY) exhibited a slow increase (early stage), rapid increase (middle stage), and then rapid decrease (late stage) trend. RD and SY in the middle stage were higher than those in the early and late stages. Moreover, during the rainfall period, soil erosion mainly occurred from July to August; during these two months, the rainfall and rainfall erosivity accounted for 66.0 and 91.1% of the total rainfall and rainfall erosivity, respectively; and the RD and SY in this period accounted for 88.4 and 89.8% of total amounts in the whole rainfall period, respectively. In addition, the contributions of snowmelt and rainfall to RD and SY were 18.6 and 81.4%, and 3.8 and 96.2%, respectively. Hysteresis analysis suggested that clockwise hysteresis loop was the dominant pattern, followed by eight-shaped anticlockwise loop, and complex anticlockwise loop. [ABSTRACT FROM AUTHOR]

Maravanthe Beach has been witnessing erosion due to waves caused by tidal forces, destroying vegetation, and causing enormous damage to people's lives, livestock, and property. Hence, an attempt has been made to understand the shoreline change analysis using the automatic shoreline extraction method and determine the rate of change in terms of erosion and accretion rate before and after the construction of coastal structures during the period from 2014 to 2023. The SWAT model was applied to analyze the influence of surface runoff on shoreline changes near Maravanthe Beach for the periods 2004–2014 and 2012–2023. Also, runoff was chosen as one of the parameters for validation of the analysis. It was noticed that the shoreline stretch had experienced significant erosion prior to the construction of shore protection infrastructure. Soon after the deployment of certain shore structures, the shoreline progressed from a high erosion stretch to a low erosion stretch. This study reveals that Maravanthe Beach witnessed greater erosion during the period 2014–2018 than it did from 2019–2023 and also observed a decrease in erosion from 11% to 3% and an increase in the accretion zones from 2 to 9%. [ABSTRACT FROM AUTHOR]

Urban parks in Vietnam are undergoing expansion plans, yet the actual area is dwindling, attributed to limited ecosystem services and inadequate public engagement. This study addressed the dual challenge of shrinking green spaces and the need for enhanced ecosystem services in urban areas. We aimed to devise strategies to bolster ecosystem service development through a comprehensive survey of park users and an analysis of the impact of green areas on ecosystem service quality. Specifically, we surveyed 400 residents to gauge perceptions, attitudes, and insights regarding park ecosystem services. Additionally, we assessed the importance of urban green spaces through various indicators (pH,DO,TSS,COD,N–NH4+,N–NO2−,N–NO3−,P–PO43−) in surface runoff samples, both with and without vegetation, during five rainfall events. The findings reveal a limited understanding of park ecosystem services among the populace, reflected in their minimal willingness to pay for such services. Moreover, the study uncovers significant differences in the impacts of parks on sustainable urban drainage, as evidenced by contrasting qualities of rainwater samples processed through green areas versus typical stormwater runoff. These results underscore the need for targeted interventions to raise awareness and improve ecosystem services in urban parks, which is pivotal for sustainable urban development. This case study from Vietnam contributes both theoretically and practically by highlighting the crucial role of public awareness and engagement in enhancing ecosystem services in urban landscapes. Practical Applications: Our study illuminates the crucial role of nature-based solutions in enhancing ecosystem services within urban environments, as exemplified by Gia Dinh and Tao Dan Parks in Ho Chi Minh City, Vietnam. This research is particularly valuable for urban developers, park management, and city planners because it underscores the potential of urban parks to contribute significantly to environmental sustainability and public well-being. We found that the public's awareness and valuation of the parks' ecosystem services are key to their willingness to support and fund park improvements. Therefore, educational programs aimed at increasing understanding of the benefits provided by these green spaces could lead to greater community involvement and investment in their maintenance and development. For policymakers, our findings suggest that investing in the ecological aspects of urban parks can pay off in terms of both enhanced environmental quality and increased public usage and enjoyment. Additionally, the implementation of sustainable drainage systems within these parks not only mitigates urban flooding but also improves the quality of urban runoff, presenting a compelling case for integrating similar nature-based solutions in urban planning initiatives. By presenting clear, real-world examples from Gia Dinh and Tao Dan Parks, our study provides a framework for other cities looking to link ecosystem services with urban development. The insights gained here can guide the transformation of urban green spaces into multifunctional areas that support biodiversity, provide recreational opportunities, and serve as cornerstones for sustainable city living. [ABSTRACT FROM AUTHOR]

Variable infiltration capacity model is used to quantitatively analyse the runoff reduction benefits of three basins on the Loess Plateau since the implementation of the 'Grain for Green' programme. The programme played an important role, contributing to >60% of the runoff variation in the different basins. Furthermore, for every 1000 km2 increase in cumulative forest area in basins, the rate of runoff coefficient reduction changed by −30%, −37.3% and 169% in the late stage of the programme compared to the early stage, respectively ('-' represents a decrease in reduction rate). This was closely related to the restoration of vegetation. [ABSTRACT FROM AUTHOR]

An understanding of turbulence and mixing is essential to the knowledge of turbulent dissipation, sediment transport, advection of nutrient-rich and organic effluents, and stormwater runoff in prototype water systems, as well as in laboratory channels used for physical modeling of geometrically-scaled full-scale water bodies and for validation of computational models. The acoustic Doppler velocimeter (ADV) system is a robust instrument well suited for such turbulence measurements in open channel flows. The application of acoustic Doppler velocimeter to transient free-surface flows is reviewed in this paper. Based upon field applications and laboratory experiments, the intricacy and inherent difficulties are discussed. The experience and expertise in transient flows highlighted the importance of the signal processing and precise synchronization. Finally, we stress a major benefit of the acoustic Doppler velocimetry for its capability to be used in both field and laboratory, in turn providing some level of confidence in the comparison between full-scale and laboratory data. [ABSTRACT FROM AUTHOR]

Rainfall erosion can cause environmental and economic damage by decreasing the storage capacity of water reservoirs because of the detachment of soil particles. The purpose of this study was to develop a one-dimensional physicomathematical model that can help predict the effects of rainfall erosion on the banks of water reservoirs. The model was developed using the Mein–Larson model to describe water infiltration, the kinematic wave approximation to represent overland flow generation, and the steady state sediment continuity equation to estimate sediment transport. The model was validated using rainfall simulator tests and lateritic soil samples with a bimodal soil–water retention curve. The results showed conformity with the experimental data, identifying a threshold in the models for discharge per unit area and sediment yield rate, as well as a linear increase in the models for total runoff and sediment load per unit area. However, the model failed to capture the peak in sediment yield rate owing to raindrop impact during the initial minutes of rainfall. Parametric analysis highlighted the impact of increasing the calibration constant of splash erosion, erodibility coefficient, and critical shear stress on the slope of the sediment load per unit area model. Despite its limitations, the model demonstrates satisfactory predictive capability for sediment load per unit area under high-intensity rainfalls, achieving an R2 greater than 0.92 in five of the six cases examined. [ABSTRACT FROM AUTHOR]

Low Impact Development (LID) measures have proven to be effective in reducing the runoff volume and the peak of runoff at small spatial scales. Assessment of the hydrological impacts of LID measures at river basin scales is currently limited by the absence of adequate physically-based process models that can simulate LID processes at such scales. In this study, an attempt has been made to develop LID modules to simulate the water balance and hydrological processes based on the Multi-Layer Green-Ampt (MLGA) infiltration method, which is an advancement to the existing LID modeling techniques. The performance of the MLGA-based LID modules was benchmarked with the process-intensive numerical tool HYDRUS 1D for about 5000 soil samples across the soil textural classes. The results indicated that the MLGA-based model simulates the hydrological processes in close agreement with HYDRUS for soils with moderate-to-high hydraulic conductivity values, which are amenable for LID implementation. [ABSTRACT FROM AUTHOR]

When using runoff infiltration devices to remove nitrogen and phosphorus pollutants from urban runoff, the quality of the effluent is affected by the length of dry spells between rain events. This study presents a novel analysis of how these dry periods impact the device's effectiveness in removing pollutants and the resulting biological succession within the filter. Our analysis examines nitrogen and phosphorus removal in a rainwater filtration context, providing new insights into how dry period duration influences infiltration system performance. The results indicate that biological processes have a significant impact on reducing total nitrogen (TN) and total phosphorus (TP) contents under different drying periods. A 3-day drying period is most effective for reducing TN through biological processes, while a 7-day period is best for TP reduction. This suggests that moderately extending the drying period improves TP removal efficiency but does not enhance TN removal. The dominant bacterial phylum responsible for denitrification and phosphorus removal is Proteobacteria, with Pseudomonas and Acinetobacter as the leading genera. As the drying period lengthens, the dominant genera shift from Pseudomonas to Massilia. At a 3-day drying period, denitrification primarily occurs through Pseudomonas on the surfaces of maifanite and zeolite. At a 7-day dry-out period, Acinetobacter is mainly responsible for phosphate removal on maifanite surfaces. However, after a 14-day dry-out period, both biomass and bioactivity of Pseudomonas and Acinetobacter decrease, leading to reduced efficiency in removing nitrogen and phosphorus pollutants from runoff infiltration devices. These results aid in developing runoff infiltration devices for specific scenarios and offer crucial guidance for regulating runoff pollution control technologies. [ABSTRACT FROM AUTHOR]

Determining the relative roles of climatic versus anthropogenic factors in runoff alterations is important for sustainable water resource utilization and basin management. The Danjiang River watershed is a crucial water resource area of the middle route of the South-to-North Water Transfer Project. In this study, four widely used quantitative methods, including the simple linear regression, the double mass curve, the paired year with similar climate conditions, and an elasticity method based on the Budyko framework were applied to detect the relative contribution of climatic and anthropogenic factors to runoff variation in the Danjiang River watershed. The calculation processes of each method were systematically explained, and their characteristics and applications were summarized. The results showed that runoff decreased significantly (p < 0.05) with an average change rate of −3.88 mm year−1 during the period of 1960–2017, and a significant change year was detected in 1989 (p < 0.05). Generally, consistent estimates could be derived from different methods that human activity was the dominant driving force of significant runoff reduction. Although the impacts of human activity estimated by the paired year with similar climate conditions method varied among paired years, the other three methods demonstrated that human activity accounted for 80.22–92.88% (mean 86.33%) of the total reduction in the annual runoff, whereas climate change only contributed 7.12–19.78% (mean 13.67%). The results of this study provide a good reference for estimating the effects of climate change and human activities on runoff variation via different methods. [ABSTRACT FROM AUTHOR]

To control and improve the phenomena of rocky desertification and soil erosion in karst landform areas, which are caused by a series of human factors that include social and economic development and human activities, China has successively introduced many policies, resulting in spatial and temporal changes in the landscape pattern of the southern karst area. In this study, land use transfer intensity maps, the grid method, the sample line method, the semivariogram method, and the Spearman analysis method are used to explore the spatial and temporal evolutions in surface runoff as responses to landscape pattern and policy factors in karst landform area. Therefore, this study provides theoretical and policy support for improving the regional landscape structure, optimizing the landscape layout, introducing regional policies, reducing surface runoff, and alleviating soil erosion. The results show that the best scale for the study of landscape patterns in the southern karst area is 3000 m. Forests are the land type that make up the highest proportion in the southern karst area, and they have the strongest interception capacity for surface runoff. The spatial and temporal distributions of the surface runoff are significantly different, and urban expansion has led to an increase in impervious runoff year over year. Runoff is positively correlated with the Shannon diversity index (SHDI), patch density (PD), and landscape shape index (LSI). The stronger the landscape heterogeneity, the more runoff. DIVISION is positively correlated with forest runoff and negatively correlated with other land types. The higher is the degree of aggregation of impervious patches, the higher the regional runoff rate. The more dispersed the forest patches are, the smaller the area proportion, and the greater the runoff. In addition, policy factors have a significant impact on surface runoff. [ABSTRACT FROM AUTHOR]

Fluoroquinolone antibiotics are pseudo-persistence in aquatic environments as emerging contaminants. In this study, the Shitoukoumen Reservoir and its four inflow rivers were selected as a typical river-reservoir system. The factors, including river input, rainfall, flow regulation, population, antibiotic half-life, and antibiotic emission path were investigated to find out the reasons for antibiotic variations in the river-reservoir system during the reservoir discharge and filling periods. The results showed that ofloxacin was the most prevalent antibiotic in both the reservoir and inflow-river water, with median concentrations of 18.6 ± 2.4 and 39.7 ± 6.2 ng L−1, respectively. The concentrations of enrofloxacin, norfloxacin, and ofloxacin in the reservoir fluctuated during the reservoir discharge and filling periods. Enrofloxacin was only detected in the reservoir during the discharge period due to its input from the inflow rivers. Artificial reservoir discharge decreased the dissolved concentrations of norfloxacin and ofloxacin in the reservoir, whereas reservoir filling increased their accumulation. The Shuangyang, Yinma, and Chalu Rivers contributed relatively high individual antibiotic mass loads to the reservoir, ranging from 66.7% to 100%. Antibiotic-containing waste runoff during rainfall events increased input contributions of antibiotics from the Shuangyang and Chalu Rivers. The risk assessments indicated that norfloxacin posed a high risk to the most sensitive algae and therefore required greater attention. The study provides a comprehensive insight into fluoroquinolone antibiotic residues in the river-reservoir system during the periods of reservoir discharge and filling, and is of importance for their future monitoring and management. [ABSTRACT FROM AUTHOR]

The paper studies the influence of shrubs in a runoff-regulating forest belt of a combined (dense–blown–lattice) design on the natural factors of meltwater runoff formation: snow accumulation, freezing depth and soil moisture. The research was conducted at the Amphitheater runoff-erosion station in agroforestry landscapes of a dry-steppe natural zone (Volgograd) with the use of the water-balance method at runoff sites. During the field experiment with different placement of shrubs in three- or four-row forest belts (in the middle, on the upper edge, on the lower edge, and on both sides), a positive role in increasing the ameliorative effect of runoff-regulating forest belts was established: reduction of freezing depth, accumulation of snow reserves, and additional moisture in the soil. In terms of impact on natural factors of meltwater runoff, the placement of shrubs in the flow-regulating forest belt of combined design on the lower and upper edges was the most effective. This measure provided better snow accumulation inside the forest belt and increased soil moisture in it. Thus, when creating new erosion control measures, it is necessary to introduce shrubbery into the composition of runoff-regulating forest belts, which affects the natural factors of runoff formation—snow accumulation, freezing depth, and soil moisture—and contributes to the reduction of surface runoff of melt water. [ABSTRACT FROM AUTHOR]

Hawassa is a rapidly developing city in Lake Hawassa watershed of Ethiopia. Analyzing the effect of land cover dynamics on surface runoff remains imperative to adaptive urban stormwater management. This study quantified spatial variation of land cover and sensitivity of stormwater management response. Historical 30 years of daily annual rainfall, three satellite imageries, DEM, and hydrological soil group data were analyzed. A statistical‐based combined approach of geospatial techniques and Soil Conservation Service‐Curve Number (SCS‐CN) model was employed. CN and surface runoff depth for the delineated urban watersheds were determined. The result revealed that the built‐up area increased by 30.9 km2, where the rate varies spatially. The variation of impervious land cover explains 58.6% of change in CN with coefficient of 0.352. While CN is inversely correlated with agricultural and vegetation land cover variations. The finding suggests CN explains 96.78% of the change in surface runoff with a significant correlation coefficient of 3.91. The proposed integrated model approach justifies the potential to reorganize the relationship between the spatial effect of land cover variation on surface runoff at the urban watersheds. Thus, suitable local‐specific solutions can be devised for effective management of flood risk and optimize the drainage system of urban areas. [ABSTRACT FROM AUTHOR]

Runoff gullies are among the most typical and common disorders in rammed earthen sites. However, only a few studies have effectively elucidated their developmental characteristics, influencing factors, and evolutionary mechanisms. Here, employing 15 sites in three climatic areas and five dynasties as the research objects and based on the investigation and statistics of runoff gullies, standard grading of gully erosions in single sites, classification of the ages of the gullies, and test for the refined disintegration processes of rammed earth using the H-FRA and AHP-EWM-TOPSIS methods, a preliminary study on the temporal and spatial characteristics of the development, as well as influencing factors of gullies, was conducted. The results indicated that the age development of the gullies in the 15 sites proceeded via alternating surface and bottom erosions and that the gullies were mainly at their early and mature stages at this time. The comprehensive degrees of gully erosion exhibited the following temporal and spatial patterns: semi-arid > extreme-arid > arid area and Ming > Han > Qing > Tang > Song Dynasties. Further, the AHP-EWM-TOPSIS model with the disintegration index positively affected the temporal and spatial variations of the comprehensive development degrees of gullies, with up to 93.33% accuracy. HIGHLIGHT: The temporal and spatial characteristics of runoff-gully development in rammed earthen sites are revealed. The runoff-gully was classified according to the age development order, and the comprehensive development degree of gully was proposed as a new index. The disintegration process tests were refined and the indexes of disintegration characteristics at different stages were obtained. AHP-EWM-TOPSIS comprehensive evaluation method was used to analyze the influence factors of the runoff-gully. [ABSTRACT FROM AUTHOR]

Seabirds are important vectors for nutrient transfer across ecosystem boundaries. In this seasonal study, we evaluate the impact of an Arctic colony (Alkhornet, Svalbard) of Black-legged Kittiwakes (Rissa tridactyla) and Brünnich's Guillemots (Uria lomvia) on stream nutrient concentrations and fluxes, as well as utilization by coastal biota. Water samples from seabird-impacted and control streams were collected regularly throughout the melt season (June–September) for nutrient and organic carbon analysis. Stable carbon and nitrogen isotope analysis (δ13C and δ15N) was used to assess whether seabird-derived nitrogen (N) could be traced into filamentous stream algae and marine algae as well as consumers (amphipods). Concentrations of nitrate (NO3−) and nitrite (NO2−) peaked in July at 9200 µg N L−1 in seabird-impacted streams, 70 times higher than for control streams. Mean concentrations of phosphate (PO43−) in seabird-impacted streams were 21.9 µg P L−1, tenfold higher than in controls. Areal fluxes from seabird-impacted study catchments of NO3− + NO2− and PO43− had estimated ranges of 400–2100 kg N km−2 and 15–70 kg P km−2, respectively. Higher δ15N was found in all biota collected from seabird-impacted sites, indicating utilization of seabird-derived nitrogen. Acrosiphonia sp. from seabird-impacted sites had higher δ15N values (20–23‰ vs. 3–6‰) and lower C:N ratios (10.9 vs. 14.3) than specimens collected from control sites, indicating reliance on seabird-derived nitrogen sources and potentially higher N-availability at seabird-impacted nearshore sites. Our study demonstrates how marine nutrients brought onshore by seabirds also can return to the ocean and be utilized by nearshore primary producers and consumers. [ABSTRACT FROM AUTHOR]

Seasonal variation in the quality of water from River Wupa, Abuja, Nigeria was studied by collecting sixty water samples in both dry and wet seasons which were analyzed using standard methods. The respective results for in dry and wet seasons were pH (7.13±0.09, 7.31±0.06), temperature (21.51±0.51, 27.66±0.49 °C), EC (247.19±46.21, 152.43±17.76 µS/cm), TDS (156.80±39.74, 75.39±9.23 mg/dm³), TSS (33.38±14.12, 333.85±43.45 mg/dm³), turbidity (26.20±13.04, 361.51±52.89 NTU), alkalinity (34.49±4.12, 29.31±3.78 mg/dm³), DO (7.73±0.29, 8.95±0.87 mg/dm³), BOD (17.00±4.90, 15.70±2.98 mg/dm³), COD (40.36±14.01, 28.28±8.18 mg/dm³), hardness (33.74±2.10, 34.82±3.82 mg/dm³), sulphate (41.09±1.01, 28.82±1.05 mg/dm³), nitrate (12.12±2.02, 12.23±1.78 mg/dm³), nitrite (0.08±0.02, 0.06±0.02 mg/dm³), phosphate (2.09±0.33, 2.15±0.35 mg/dm³) and chloride (40.96±3.53, 32.23±3.82 mg/dm³). Correlation results shows that during the dry season there is a strong and positive correlation between (EC and TDC, r =0.910), (TSS and Turbidity, r = 0.976), (TSS and BOD, r = 0.945), (TSS and COD, r = 0.912), (Turb and BOD, r = 0.868), (Turbidity and COD, r = 0.820), (BOD and COD, r = 0.979), (pH and nitrite, r = 0.750) (pH and Cl, r = 0.737), (TSS and Cl, r = 0.748) and (Turb and Cl, r = 0.761). During the wet season strong and positive correlation is between (EC and TDS, r = 0.879), (BOD and COD, r = 0.756) and (Turbidity and sulpate, r = 0.730). Results for all parameters were below the limits recommended by NSDWQ except for turbidity, DO and phosphate, also in both seasons there was no significant difference for all parameters except for turbidity and COD. It is concluded that the variation in these two parameters is attributable to runoffs from farmlands and direct discharge of domestic and industrial effluent during the wet season and the strong and positive correlation indicates that the pollutants that affect water quality parameters come from the same sources. [ABSTRACT FROM AUTHOR]

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This paper presents an innovative, original approach to co-design retention ponds and floating photo voltaic solar plants as a water-energy nexus approach to reduce flooding and energy burden for one location. Case-study analysis was conducted in Waimanalo, Hawai'i. A flood model--from a previous study--was used to provide a potential location for a retention pond and floating solar photovoltaic panels. This study found the co-design of retention ponds and floating PV solar can not only reduce future stormwater runoff by up to 50% but provide a total of 50% of onsite solar energy at a neighbourhood scale, demonstrating how clean energy and green infrastructure can help advance environmental and social justice. Several takeaways from this study were taken into account and things to consider for a follow-up paper. One of the major challenges was finding a potential suitable location. Overcoming this challenge required using Google Maps and the flood model to pinpoint high flood accumulation and searching for a large green space that is in close vicinity to a developed neighbourhood. [ABSTRACT FROM AUTHOR]

We present the core support criterion, a voting criterion satisfied by Instant Runoff Voting (IRV) that is analogous to the Condorcet criterion but reflective of a different majority rule philosophy. Condorcet methods can be thought of as conducting elections between each pair of candidates, counting all ballots to determine the winner of each pair-election. IRV can also be thought of as conducting elections between all pairs of candidates but for each pair-election only counting ballots from voters who do not prefer another major candidate (as determined self-consistently from the IRV social ranking) to the two candidates in contention. The appropriateness of including all ballots or a subset of ballots for a pair-election, depends on whether the society deems the entire or a selected ballot set in compliance with freedom of association, which implies freedom of non-association, for a given pair election. Arguments based on freedom of association rely on more information about an electorate than can be learned from ranked ballots alone. We present a freedom-of-association based argument to explain why IRV may be preferable to Condorcet in some circumstances, including the 2022 Alaska special congressional election and the 2009 Burlington Vermont mayoral election, based on the political context of those elections. [ABSTRACT FROM AUTHOR]

Fractionation of sediment-bound nitrogen (N) in Thrissur Kole wetland was carried out to assess the mobility, bioavailability, and nutrient contamination status. Various N fractions were extracted using KCl equilibrium extraction method, and the concentration of each N fraction was analyzed by spectrophotometric method. Dominance of ammonia during all seasons was due to dissimilatory NO3− reduction to NH4+ and direct inputs from agriculture fields. Enrichment of urea during post-monsoon (181.78 ± 8.47 ppm) was attributed to fertilizer sources. NO3−-N deficit at central zone of the study area (monsoon and post-monsoon) was due to the anoxia. Comparatively higher values of NO2−-N during monsoon (0.07 ± 0.02 ppm) was due to the land run-off, leaching of fertilizers from agriculture fields, and higher rate of denitrification. Elevated content of total N [1819.94 ± 40.20 ppm (pre-monsoon); 3061.62 ± 13.21 ppm (monsoon); 2763.44 ± 9.65 ppm (post-monsoon)] reflected the inputs from in-situ production, agriculture, terrestrial run-off, waste disposal, and guano as well as carcass of birds. Average contribution of bioavailable N to total N was higher (36.16%) indicated the possibility for eutrophication risk during pre-monsoon. Agriculture dominated regions recorded severe contamination and eutrophication risk as indicated by organic pollution index, organic nitrogen index, and phosphorous pollution index. [ABSTRACT FROM AUTHOR]

The Gulf of St. Lawrence (GSL), along with the St. Lawrence Estuary, is the largest estuarine system in North America. It is a biologically productive sea and an important fishing ground in Canada. The objectives of this study are to determine how climate changes will affect primary production in the GSL and on the eastern Scotian Shelf, and to determine the drivers of the changes. We use a regional ocean model forced with downscaled output of the Max-Planck Institute Earth System Model to study the changes in net primary production under the climate change scenario of Representative Concentration Pathway 8.5 (RCP8.5). Results reveal a projected 13.4% decrease in annual primary production across the GSL system over the next 70 years. This decline primarily stems from reduced nutrient concentrations in the upper layer, despite the increase in nutrients supplied by rivers. Enhanced freshwater influx and ocean surface warming contribute to heightened stratification, that in turn reduce the vertical nutrient fluxes from deeper layers. This mechanism affects the upwelling of nutrient-rich water at the head of the Laurentian Channel in the Lower St. Lawrence Estuary, leading to a 22% reduction in the vertical nitrate flux in the future. Additionally, nutrient concentrations in the water masses entering the GSL at the Strait of Belle Isle and at Cabot Strait are also reduced. Due to declining sea-ice concentration, the phytoplankton bloom is expected to occur between 9 and 23 days earlier under a warmer climate, and last for up to 24 days longer, depending on the GSL subregions, compared to the historical period (2001-2020). Biological productivity at higher trophic levels, and thus fisheries productivity, could be negatively impacted under the RCP8.5 climate change scenario. [ABSTRACT FROM AUTHOR]

Mulching is one of the best management practices used in soil and water conservation studies. The aim of this study is to determine the effects of different mulch types and doses on runoff coefficient (Rc), soil loss (Er), sediment concentration (Sc), time to ponding (tp), runoff generation time (tr), percolated (pw) and retained (rw) water and total losses of nitrate‐nitrogen (NO3−), ammonium‐nitrogen (NH4+), total nitrogen (TN), phosphate‐phosphorus (PO43−), and total organic carbon (TOC) under simulated rainfall in the laboratory. Three different mulch materials (dry weed, peanut hay, and wheat straw) were applied at four different doses (0, 2, 4, and 6 t/ha) on the experimental plots. A simulated rainfall intensity of 97 mm/s was applied for an hour. All mulch types and doses reduced Rc, and the most effective reduction was found in 2 t/ha dry weed mulch applied plots. The most effective application for reducing soil loss was 6 t/ha peanut hay mulch. The most effective application for delaying the ponding time and runoff generation time was the 4 t/ha application of wheat straw mulch. The highest pw and rw were found in 6 t/ha and 4 t/ha doses of dry weed mulch applications, respectively. The most effective application for reducing NH4+ losses was found in 4 t/ha wheat straw application plots. The most effective mulch type and dose for reducing NO3− loss was 6 t/ha of dry weed mulch. The lowest TN loss was found in the plots where 6 t/ha of peanut hay mulch was applied. In terms of PO43− losses, the lowest loss was in 6 t/ha of dry weed mulch plots. The lowest TOC loss was at 4 t/ha of straw mulch applications. Mulching can be a good natural‐based solution for reducing soil, water, and nutrient loss. However, different mulch types and doses should be tested for different environmental conditions to determine the most cost‐effective mulch type and dose. [ABSTRACT FROM AUTHOR]

Reliable hydrological simulations require accurate precipitation data. However, data uncertainties due to the indirect nature of satellite estimates can propagate through hydrological models and lead to simulation errors. This study assesses the accuracy of Global Precipitation Measurement (GPM) Integrated Multi-satellite Retrievals for GPM (IMERG) products, comparing them directly with ground-based precipitation data and evaluating their performance in rainfall–runoff modelling across Great Britain. Three IMERG V06 products (IMERG-Early, IMERG-Late, and IMERG-Final) are examined. Utilizing the simple water balance model (SWBM), the analysis covers 250 basins, revealing that the SWBM performs well in over 50% of the basins. Runoff estimations show that European Observation (E-OBS) ground-based data yield the highest Nash-Sutcliffe efficiency (NSE) score (0.91), followed by IMERG-Final (0.85), IMERG-Late (0.82), and IMERG-Early (0.73). The findings underscore IMERG’s utility in hydrological modelling for ungauged or poorly gauged basins. [ABSTRACT FROM AUTHOR]

In this study, the impact of change in land use and land cover (LULC) on runoff estimation in the Kidangoor watershed was assessed using the SCS-CN technique. Recent flood-like natural disasters in Kerala are thought to be driven by changes in rainfall patterns and LULC. The accurate calculation of runoff from watersheds is urgently needed. In ArcGIS 10.5, the supervised classification approach is used to classify satellite images from 2000, 2011, 2013, and 2017. Similarly, the Inverse Distance Weighted (IDW) technique is used to produce spatial distribution maps of rainfall for each antecedent moisture condition (AMC). The runoff maps were generated by superimposing the distributed rainfall, LULC, and Hydrological Soil Group (HSG) maps. It was observed that the built-up area expanded by 168% between 2000 and 2017, whereas other classes decreased by 10-23%. However, compared to 2000, both with and without a change in LULC, runoff generation increased by just 31%, and 27% in 2017. The SCS-CN technique for runoff estimation indicates that the change in LULC in the Kidangoor watershed is insignificant. Thus, this study will help land use planners and decision-makers in limiting the potential damage from flooding when it comes to flood management techniques. [ABSTRACT FROM AUTHOR]

Wildfire disturbance propagation along fluvial networks remains poorly understood. We use incident, atmospheric, and water-quality data from the largest wildfire in New Mexico's history to quantify how this gigafire affected surface runoff processes and mobilized wildfire disturbances into fluvial networks after burning 1382 km2. Surface runoff post-fire increased compared to pre-fire conditions, and precipitation events that are frequently observed in the affected watershed (<2-year recurrence) and fell during the post-fire first rainy season resulted in uncorrelated, less frequently observed runoff events (10-year recurrence). Besides these shifts in runoff generation, the magnitude and fluctuation of daily water quality parameters and relevant ecosystem processes also shifted over multiple months, even at sites located >160 km downstream of the burn perimeter. Our findings emphasize the need to incorporate spatially resolved longitudinal sampling designs into wildfire water quality research and highlight the spatiotemporal co-dependency among atmospheric, terrestrial, and aquatic processes in defining the net outcome of wildfire disturbance propagation along impacted fluvial networks. This study quantifies how the largest wildfire in New Mexico's history altered runoff processes and generated water quality disturbances that propagated along hundreds of kilometers and over multiple months, affecting key aquatic ecosystem processes. [ABSTRACT FROM AUTHOR]

Debris flows and floods generated by rainfall runoff occur in rocky mountainous landscapes and burned steeplands. Flow type is commonly identified post‐event through interpretation of depositional structures, but these may be poorly preserved or misinterpreted. Prior research indicates that discharge magnitude is commonly amplified in debris flows relative to floods due to volumetric bulking and increased frictional resistance. Here, we use this flow amplification to develop a metric (Q*) to separate debris flows from floods based on the ratio of observed peak discharge to the theoretical maximum water discharge from rainfall runoff. We compile 642 observations of floods and debris flows and demonstrate that Q* distinguishes flow type to ∼92% accuracy. Q* allows for accurate identification of debris flows through simple channel cross‐section surveys rather than through qualitative interpretation of deposits, and therefore should increase the performance of models and engineered structures that require accurate flow‐type observations. Plain Language Summary: Steep channels in rocky landscapes and recently burned areas carry a wide range of flow types, ranging from water floods to highly destructive debris flows composed of rock, sediment, other incidental debris, and water. Typically, the flow type that recently occurred in a channel is identified by interpreting the structure of deposits left behind by the flow. However, these deposits can be challenging to interpret, provided they are preserved at all. Prior research has shown that the shift in flow physics occurring in debris flows has the effect of amplifying the magnitude of the flow beyond that which is possible in floods. In this study, we take advantage of this flow amplification to develop a quantitative metric that allows for flow type to be identified without interpreting depositional structures. We demonstrate the metric to be highly accurate. This methodology should increase the accuracy of predictive models trained on such observations, which can help to better understand where these hazards exist and protect communities and infrastructure at risk. Key Points: To distinguish debris flows from floods, a metric Q* equal to the ratio of peak discharge to rainfall‐runoff discharge is developedQ* separates floods (Q* ≤ 1) from debris flows (Q* > 1) to ∼92% accuracy and is robust to uncertainties in the key parametersThe Q* metric should reduce misidentification of flow type and increase the performance of empirical‐hazard models and hazard mitigation [ABSTRACT FROM AUTHOR]

There is ample evidence for ice layers and lenses within glacial firn. The standard model for ice layer formation localizes the refreezing by perching of meltwater on pre‐existing discontinuities. Here we argue that even extreme melting events provide insufficient flux for this mechanism. Using a thermomechanical model we demonstrate a different mechanism of ice layer formation. After a melting event when the drying front catches up with the wetting front and arrests melt percolation, conductive heat loss freezes the remaining melt in place to form an ice layer. This model reproduces the depth of a new ice layer at the Dye‐2 site in Greenland. It provides a deeper insight into the interpretation of firn stratigraphy and past climate variability. It also improves the simulation of firn densification processes, a key source of uncertainty in assessing and attributing ice sheet mass balance based on satellite altimetry and gravimetry data. Plain Language Summary: Firn covers a significant portion of Earth's glaciers and ice sheets. It can store surface meltwater and prevent runoff into the ocean. The widespread presence of ice layers embedded in firn formed by meltwater refreezing may prevent meltwater storage and contribute to sea level rise. However, current models of ice layer formation, originally developed for snow, do not seem to work in firn. This work presents a different mechanism for ice layer formation without invoking pre‐existing ice layers within the firn. Our model shows that the sequencing of ice layers formed by subsequent melting events depends on the overall heat added to the firn. Deeper layers occur in warmer, more porous firn during intense melt events in a warming climate. This insight enhances our understanding of firn layering and can help deduce past climate variations. Our model aids in understanding the density evolution of firn to reduce uncertainties in remote sensing data that determines the ice sheet mass loss and its contribution to global sea‐level rise. Key Points: A new ice layer forms without meltwater perching when freezing localizes after a melt event as heat conduction dominates over advectionDeeper ice layers form in warming climatic conditions whereas denser ice layers form near surface in net‐zero climatic conditionsResults indicate the possibility of deducing past variability in climate from firn stratigraphy and vice versa [ABSTRACT FROM AUTHOR]

The present study assessed the heavy metal pollution in sediment samples collected from the Noyyal River basin (river and lake sediments) during the monsoon and summer seasons. The geo-accumulation index (Igeo) categorizes metals as extremely polluted during monsoon and heavily contaminated to extremely contaminated during summer. The enrichment factor (EF) of metals Mn during monsoon and Cd during summer indicates extremely severe enrichment (EF > 50) and Mo exhibited very high contamination (CF > 6) throughout the basin during monsoon. The average risk index of heavy metal in the basin followed the order Cd (164.15) > Ni (14.82) > Co (4.84) > Cr (2.55) > Cu (1.89) > Zn (1.38) > Mn (0.40) during monsoon and Cd (153.07) > Ni (7.96) > Cu (5.13) > Co (4.63) > Cr (1.89) > Zn (1.21) > Mn (0.3) during summer showing that the PERI of each element was minimal except for Cd. Adverse health-related effects are confirmed by the cumulative total hazard index (THI) for children with HQ ingestion and HI values >1 in all sample locations over both seasons. Principal component and cluster analysis show metals accumulate in sediments mainly through industrial wastewater discharge and also experience significant natural source weathering through rainfall runoff. This research emphasizes the need for enhanced wastewater treatment facilities in metropolitan areas situated along the Noyyal River to potentially reduce the release of heavy metals from both domestic and industrial sources. [ABSTRACT FROM AUTHOR]

Vegetation restoration is among the most effective measures for controlling runoff and soil erosion resulting from human activities. Nevertheless, few studies have been undertaken to analyze the effects of grassland restoration on maintaining local runoff, especially on alpine degraded hillsides where mixed-cultivation grasslands predominate. In this research, runoff plots were established to investigate the impact of three mixed-cultivation grasslands, each sowing two grass species per plot on a 20° slope: Deschampsia cespitosa and Elymus nutans (DE), Poa pratensis L. cv. Qinghai and Elymus nutans (PE), and Poa pratensis L. cv. Qinghai and Deschampsia cespitosa (PD). The activation and volume of surface runoff and the magnitude of soil loss on alpine degraded hillsides over 3 years (2019, 2020, and 2022) were assessed. A severely degraded meadow (SDM) plot was used as a control. The findings indicated that mixed-cultivation grasslands can effectively maintain runoff and reduce soil loss as planting age increases. Between 2019 and 2022, the values of the average runoff depth for DE, PE, PD, and SDM were 0.47, 0.55, 0.45, and 0.27 mm , respectively. Despite the increase in runoff, grassland restoration favored soil conservation: the net soil losses per unit area of SDM were 1.4, 1.3, and 1.9 times greater than those in DE, PE, and PD, respectively. The key factors affecting soil loss and runoff were rainfall amount, duration, and intensity (60 min intensity). We conclude that the results of this study can serve as scientific guides to formulate efficient policy decisions for planning the most effective vegetation restoration in severely degraded hillside alpine meadows. To improve the effectiveness of grassland restoration, we suggest that protective measures should be prioritized during the initial planting stage of cultivated grasslands. [ABSTRACT FROM AUTHOR]

The uncertainty of hydrological forecasts is strongly related to the uncertainty of the rainfall field due to the nonlinear relationship between the spatio-temporal pattern of rainfall and runoff. Rain gauges are typically considered to provide reference data to rebuild precipitation fields. However, due to the density and the distribution variability of the rain gauge network, the rebuilding of the precipitation field can be affected by severe errors which compromise the hydrological simulation output. On the other hand, retrievals obtained from remote sensing observations provide spatially resolved precipitation fields, improving their representativeness. In this regard, the comparison between simulated and observed river flow discharge is crucial for assessing the effectiveness of merged precipitation data in enhancing the model's performance and its ability to realistically simulate hydrological processes. This paper aims to investigate the hydrological impact of using the merged rainfall fields from the Italian rain gauge network and the NASA Global Precipitation Measurement (GPM) IMERG precipitation product. One aspect is to highlight the benefits of applying the cellular automata algorithm to pre-process input data in order to merge them and reconstruct an improved version of the precipitation field. The cellular automata approach is evaluated in the Tanaro River basin, one of the tributaries of the Po River in Italy. As this site is characterized by the coexistence of a variety of natural morphologies, from mountain to alluvial environments, as well as the presence of significant civil and industrial settlements, it makes it a suitable case study to apply the proposed approach. The latter has been applied over three different flood events that occurred from November to December 2014. The results confirm that the use of merged gauge–satellite data using the cellular automata algorithm improves the performance of the hydrological simulation, as also confirmed by the statistical analysis performed for 17 selected quality scores. [ABSTRACT FROM AUTHOR]

Implementing rain garden (RG) designs is widespread worldwide to reduce peak flow rates, promote stormwater infiltration, and treat pollutants. However, inadequate RG design degrades its hydrological behaviour, requiring the development and validation of an appropriate hydrological model for the design and analysis of structures. This study aimed to improve a hydrological infiltration model based on Darcy's law by taking into account the height of the water column (HWC) at the surface of the RG and the filtration coefficients of soil materials. The model was tested by simulating the hydrological characteristics of a rain garden based on a single rain event of critical intensity (36 mm/h). Using the validated model, design curves were obtained that predict the performance of the RG as a function of the main design parameters of the structure: water column height, ratio of catchment area to structure area, layer thickness, and soil filtration coefficient. The hydrological efficiency of the RG was evaluated in terms of the time of complete saturation, filling of the structure with water, and determining the change in HWC caused by changes in the parameters. The filtration coefficient and thickness of the upper and intermediate infiltration layers of the RG are the main parameters that affect the depth of saturation of the layers of the structure and the HWC on the surface. The model is not very sensitive to the model parameters related to the lower gravel layer. If the top layer's thickness increases by 10 cm, it takes longer to fill the structure with water, and the HWC on the surface reaches 0.341 m. The rain garden's performance improves when the filtration coefficient of the top layer is 7.0 cm/h. Complete saturation and filling of the structure with rainwater do not occur within 7200 s, and the water column reaches a height of 0.342 m at this filtration coefficient. However, the rain garden's effectiveness decreases if the filtration coefficient of the upper and intermediate layers exceeds 15 cm/h and 25 cm/h, respectively, or if the catchment area to RG area ratio decreases to values below 15. The modelling results confirm that considering the HWC in RG hydrological models is essential for designing structures to minimise the risk of overflow during intense rainfall events. [ABSTRACT FROM AUTHOR]

This study analyzed 61 years of hydrological data from the Minhe and Xiangtang Hydrological Stations (1956–2016) to examine hydrological changes and ecological flow assurance rates in the Huangshui River Basin, China. Using the Mann–Kendall trend test, IHA/RVA method, and ecological flow calculation methods, the study revealed the following results: (1) After 1994, increased human activity in the Datong River led to a measured runoff decrease compared to natural runoff. Although human activities in the Huangshui River's main stream were present before 1972, after 1972, these activities intensified, resulting in a more pronounced decrease in the measured runoff. (2) Ecological flow analysis indicated that the main stream of the Huangshui River and the Datong River have ecological flow assurance rates of 100% for all but a few months, where the rates are 98%. The water volume is sufficiently abundant to meet ecological water demands. [ABSTRACT FROM AUTHOR]

Increased urbanization coupled with climate change is increasing the number and intensity of stormwater flooding events. Implementing efforts to successfully manage stormwater flooding depends on understanding how people perceive these events. While images of stormwater flooding abound, how these images influence perceptions about flooding events or management options remains understudied. Our objective is to contribute to the general understanding of how various types of images depicting stormwater runoff and stormwater related flooding influence individual and group interpretations of causes of events, major impacts of those events, and responsibility for managing stormwater related events. To this end, we convened focus groups, gave participants numerous photos of stormwater flooding, asked them to identify which images were most concerning, and to then discuss the specific aspects of the photos that prompted concern. We also tested whether a priming image implicating climate change or development as a cause of stormwater flooding influenced viewer reactions. Finally, we asked participants about preferences for who should manage stormwater. Our results revealed that photo location, the water's appearance, and what people were doing in the photo influenced levels of concern. We also found that priming seems to affect opinions regarding urban stormwater management. Finally, there is some evidence that the absence of people in the photo may affect beliefs about who should manage stormwater. [ABSTRACT FROM AUTHOR]

In recent years, global climate change has become more and more obvious, and extreme rainfall weather has occurred frequently, which has a serious impact on people's life and property safety. In order to reduce the risk of urban flooding and contribute to the sustainable development of the urban economy, society, and environment, this study takes Zhengzhou City as the study area. The surface runoff during extreme rainfall events from 2005 to 2023 was simulated using the SCS-CN model, and the spatiotemporal patterns of surface runoff during extreme rainfall conditions and their influencing factors were investigated. The results showed that (1) the average annual extreme rainfall in the study area was 95.6 mm, and the average annual surface runoff was 76.5 mm, with cultivated land contributing the most to surface runoff, accounting for more than 50%. The annual average frequency of extreme rainfall in the study area ranged from 0 to 3 times. (2) During the extreme rainfall events in 2021 and 2023, the surface runoff of the main urban area was relatively great. Under the influence of impermeable surfaces, the surface runoff of the main urban area was greater than that of the surrounding area, even when the rainfall in the main urban area was less than that in the surrounding urban area. In addition, during these two extreme rainfall events, the surface runoff in the slight slope (<5°) area was the greatest; overall, the larger the slope was, the smaller the surface runoff. (3) Differences between rainfall and surface runoff (DRS) of the different administrative districts in the study area showed three trends from 2005 to 2020, with those of most areas showing a clear decreasing trend, which was affected mainly by the surface runoff potential of the land use type. Under the same rainfall conditions (110 mm), the surface runoff of urban land and construction land was 1.4–2.5 times that of various types of woodland and grassland. From 2005 to 2020, the area of urban land and other construction land increased by 104.13%, the coverage area of woodland and grassland decreased by 35.90%, and the surface runoff potential increased in most areas of the study area. To reduce the risk of urban waterlogging, most areas of Zhengzhou, especially the main urban area and slight slope areas, need to rationally regulate land use and increase the coverage ratio of woodland and grassland. [ABSTRACT FROM AUTHOR]

With the global climate change intensified, Chinese regional water resources shortage is becoming increasingly serious. Using adequate method to study the varied pattern on runoff is particularly important for water resources planning and management. Based on the time series of mountain runoff from 1956 to 2018 in Shiyang River Basin, the periodic change, abrupt change and trend change of mountain runoff series in Shiyang River Basin were analyzed by using extreme-point symmetric mode decomposition (ESMD) method, and the Morlet wavelet analysis method, Mann-Kendall test method and R/S analysis method were used for comparative verification analysis. The results show that the ESMD method can analyze and process runoff data efficiently. The runoff series of Shiyang River has periodic changes of 3.0 years, 7.3 years, 12.6 years, and the time of mutation is different under different time scales, and the time of abrupt change in different time scales is also different. And forecast shows that the runoff in Shiyang River Basin will continue to increase in short term, but it will inevitably decrease in the long term. [ABSTRACT FROM AUTHOR]

Previous research on watershed assessments has primarily emphasized general hydrological or technical findings, neglecting the spatiotemporal analysis of landuse change and its influence on surface runoff. This study addresses this gap by using a geographic information system (GIS)-based method to analyze surface runoff variations due to land-use change on Tsushima Island, Japan. By leveraging spatiotemporal analysis within a GIS framework, the study interprets satellite imagery (Landsat 8 data, 2014-2024) to assess land use and watershed characteristics. This approach culminates in a comprehensive map depicting potential flood risk across the island. In conclusion, this study offers an advanced method for communicating potential flood risks to the public and policymakers, enabling proactive mitigation strategies for the coming decade. [ABSTRACT FROM AUTHOR]

Urban runoff appears to be a pathway for transferring new emerging pollutants from land-based sources to the aquatic environment. This paper aimed to identify and describe the groups of pollutants present in rainwater surface runoff as well as their mixture with wastewater in the combined sewer system from urbanized catchments and to determine the correlations between these pollutants. Four leading groups of new emerging pollutants have been identified that may be present in rainwater and municipal wastewater mixtures. The samples were tested for microplastics, phthalic acid esters, pesticides, and polycyclic aromatic hydrocarbons as well as basic parameters. The pilot site was Słupsk (northwestern Poland). We conducted nine sampling campaigns at three points. The results of the present study revealed that (i) polycyclic aromatic hydrocarbons were not present in the tested samples; (ii) the selected organochlorine pesticides were detected during one campaign in the dry season and therefore were not of critical importance; (iii) out of the 11 analyzed phthalic acid esters, five selected substances released from commonly used plastic products were present; and (iv) the number of microplastics contained in the tested samples ranged from 1,400 to 14,036 pcs/L and even occurred during pure rainfall. [ABSTRACT FROM AUTHOR]

The inhabitants of the arid plain of northwest San Luis harvest rainwater in impoundments (small dams) to support cattle and goat production in native forests. This ancient technology has been complemented, in the last two decades, by aqueducts that transport water from the central mountains of San Luis (Nogolí dam). In this study, we 1) present an approach to social perceptions and local knowledge about impoundments; 2) implement technological improvements in six of them to increase the efficiency of water harvesting and storage, and 3) characterize the temporal dynamics of the regional water resource (impoundments and Nogolí dam). To achieve this, we conducted surveys with impoundment users, installed water level sensors, hired road machinery for improvements, and analyzed existing databases. The survey results showed that the impoundments, far from being mere water reservoirs, constitute the cultural heritage of rural families. The application of technological improvements significantly increased the maximum average water level of the enhanced impoundments, from 144 to 220 cm (P<0.05), resulting in a 113% increase in the average maximum stored volume, reaching 1282 m³ (P<0.05). The daily water level of the improved impoundments was higher than control ones (on average, 110 vs. 62 cm, respectively; P<0.01). The water supply from the impoundments exhibited complementarities concerning the temporal dynamics of the Nogolí dam in terms of the speed of response to rainfall and the time lag between filling and emptying. This study provides key knowledge to achieve ‘water sovereignty’ in the arid plain of northwest San Luis by proposing the enhancement of existing impoundments and the use of the aqueduct as a complement to them. [ABSTRACT FROM AUTHOR]

Bioretention is a type of stormwater best management practice that can reduce stormwater runoff volume, and with appropriate design, simultaneously reduce nitrogen loads. To meet the water quality potential of bioretention systems, improved simulation models of the transport and transformations of nitrogen are needed. In this work, two versions of a three-nitrogen-pool (3P) model (3P-1 and 3P-m) are applied to simulate observed nitrogen transport through a field bioretention system. The 3P models provide predictions of net export of dissolved organic carbon, dissolved organic nitrogen, and inorganic nitrogen species. The 3P-m model has promising results: (1) relative to the Storm Water Management Model (SWMM), it reduced the prediction error of percent removal of total dissolved nitrogen by up to 10.6% and reduces the scaled root-mean square error of total dissolved nitrogen loads by up to 53.0%; (2) it successfully captured the correlation between impactful environmental factors and event mean concentrations of total dissolved nitrogen and nitrate nitrogen in underdrain effluent; (3) its predictions on denitrification showed good alignment with observed isotope results; and (4) it demonstrated higher stability in simulated time series among calibration results than 3P-1. The 3P-m is expected to assist the design of bioretention system and valve control strategies by providing more accurate predictions on nitrogen removal under the impacts of soil moisture content and temperature. Future research and collaboration opportunities are also proposed in this article. [ABSTRACT FROM AUTHOR]

Debris flow mobility can vary during propagation due to changes in flow volume and bulk flow behavior resulting from the absorption of water from runoff. This study aims to investigate the effect of runoff on debris flow propagation by presenting an integrated model that considers the processes of rainfall, vegetation interception, soil infiltration, runoff generation, and debris flow propagation. Specifically, the study adopts an elevation-based empirical formula to evaluate the spatial distribution of rainfall and introduces a parameter for water absorption rate into the depth-averaged two-layer model that is used for describing the dynamics of runoff and debris flow. Through alternative simulations of the 2020 debris flow in the Meilong catchment, the study illustrates the significant effects of water absorption on debris flow propagation. The results indicate that as the water absorption rate of the debris mass increases, debris flow mobility also increases, since more mass and energy are transferred from runoff to debris flow. In addition, the spatial and temporal patterns of rainfall intensity can modify the propagation velocity of debris flow by influencing runoff dynamics. [ABSTRACT FROM AUTHOR]

A new pre-processing methodology for gridded Satellite Precipitation Products (SPPs) is developed to improve the performance of Machine Learning (ML) algorithms for runoff prediction. The developed approach was applied to capture the rainfall patterns, and to select relevant input data. This approach was tested using the FeedForward Neural Network (FFNN) and the Extreme Learning Machine (ELM) given their flexibility and ability in hydrological modelling. The methodology was tested in a semiarid transboundary watershed located in North Africa (Algeria, Tunisia) with the Integrated MultisatellitE Retrievals for Global Precipitation Measurement (GPMIMERG) and the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) products. The results demonstrate the effectiveness of the proposed approach using all employed SPPs. In terms of Nash-Sutcliffe efficiency, the suggested pre-processing technique improved the prediction ability of FFNN by 13%, and of ELM by 15%, which highlights how pre-processing techniques significantly enhance ML models with SPP data. [ABSTRACT FROM AUTHOR]

[Objective] The aims of this study are to explore the scale effect in the process of runoff and sediment movement on the slope, to clarify the scale effect influence mechanism of runoff and sediment movement in the hilly and gully region of the Loess Plateau, so as to provide scientific support for the study of runoff and sediment transfer mechanism and the comprehensive management of runoff and sediment in the Yellow River Basin. [Methods] Based on the runoff and sediment data of four runoff fields in Zizhou runoff test station of the Yellow River, the scale transfer effect of runoff and sediment yield on slope was revealed by comparing and analyzing the runoff and sediment yield processes of different slope lengths under rainfall events. The concept of scale transfer efficiency was proposed to characterize the runoff and sediment transfer relationship between the upper and lower levels, and to further explore the influencing factors on runoff and sediment transfer efficiency. [Results] (1) The characteristics of different rainfall types had different effects on the runoff and sediment yield on the slope. The rainfall duration mainly affected the runoff and sediment yield on the slope, and the average rainfall intensity mainly affected the starting time of runoff and sediment yield on the slope. (2) Under the event of rainfall, the runoff transfer of different slope lengths was an ideal equilibrium transfer mechanism, and with the increase of slope length, the transfer capacity of runoff showed a decreasing trend. Under the condition of 40~60m slope length, the transfer of sediment was a non- equilibrium transfer process. With the increase of slope length, the transfer capacity of sediment increased first and then decreased. (3) The influencing factors on flow-sediment transfer efficiency on different scale slopes were different. Runoff depth, average rainfall intensity and surface soil moisture content after rain were the main factors affecting the transfer efficiency of flow-sediment scale. [Conclusion] The runoff and sediment yield capacity of the slope in the loess hilly and gully region is affected by rainfall characteristics and slope length. There is a significant scale effect of damage or gain in the transmission of runoff and sediment along the way. The efficiency of water and sediment transport is regulated by multiple factors such as rainfall intensity, runoff and soil moisture. [ABSTRACT FROM AUTHOR]

[Objective] The aims of this study are to investigate the spatial and temporal changes of runoff and sediment load in the Kuye River Basin, to quantify the contribution of climate change and human activities to variation of runoff and sediment load, and to provide scientific basis for the rational use of water resources and the optimal allocation of soil and water conservation measures in the Kuye River Basin. [Methods] Based on the runoff, sediment load and rainfall data of Xinmiao, Wangdaohengta, Shenmu and Wenjiachuan hydrological stations in Kuye River Basin from 1960 to 2020, the spatial and temporal variation characteristics of runoff and sediment load were analyzed by the linear trend method, Mann-Kendall trend test and Pettitt mutation test, and the double mass curve was used to quantitatively analyze the contribution rate of climate change and human activities to runoff and sediment load variation in different periods. [Results] Annual runoff and sediment load in the Kuye River Basin showed a significant decreasing trend from 1960 to 2020 (p<0.01). The runoff reduction rates of Xinmiao, Wangdaohengta, Shenmu and Wenjiachuan hydrological stations were 2.4 million m³/a, 3.4 million m³/a, 8.1 million m³/a, 10.6 million m³/a, the reduction rates of sediment load were 0.438 million t/a, 0.693 million t/a, 1.603 million t/a and 2.721 million t/a, respectively. The annual runoff and sediment load of each hydrological station changed abruptly both in 1979 and 1996, so the runoff and sediment load sequences could be divided into the reference period (1960-1979, P1) and the change period (1980-1996, P2;1997-2020, P3). During the study period, the average annual runoff depth and sediment load modulus of different sub-basins showed a decreasing trend, but there were differences in space. [Conclusion] The increasing human activities (water conservancy and soil conservation measures, coal mining, etc.) are the dominant factors on variation of runoff and sediment load in the Kuye River Basin. Compared with the base period, the runoff and sediment load of each hydrological station decreased in both P2 and P3 periods, and reduction was more intense in P3 period. In the P2 and P3 periods, the contribution of human activities to the reduction of runoff sediment transport was higher than that of rainfall changes. [ABSTRACT FROM AUTHOR]