Flood Conditions Research Articles

Numerical simulation of three-dimensional seepage field in a tailing pond under multiple operating conditions.

Establishing strong seepage stability for tailings dams is crucial for ensuring their safety and mitigating the risk of failure. This study developed a three-dimensional seepage numerical model using finite element numerical computation for four different elevation conditions (5070m, 5081m, 5159m, and 5213m) encompassing the pond area and dam body. Seepage calculations were conducted under normal and flooding conditions, and the tailings pond's seepage stability was assessed for various stacking scenarios. The spatial distribution pattern of the infiltration surface and the hydraulic stability of the tailings pond were evaluated, which provides insights into the three-dimensional infiltration stability. Examining the seepage stability under different accumulation conditions revealed distinct spatial distribution patterns of the infiltration surface and hydraulic ratio drop values. The findings indicated that the maximum permeability slope at 5070m elevation ranged from 0.66 to 0.75 at normal operation water level and maximum flood level. Most hydraulic ratio drop values at 5081m were below 0.2, while the anti-seepage lining sections at 5159m and 5213m showed larger values, and maintained the overall hydraulic ratio drop within safe limits. Consequently, the dam body's permeability was deemed secure, and no infiltration damage was anticipated with the proposed design of seepage control and drainage facilities. Moreover, sensitivity analysis of the tailing sand's permeability coefficient demonstrated that variations between 0.2 and 5 times the given parameter align with the seepage control requirements for the tailings dam. Additionally, local geomembrane breakage was found to have minimal impact on the tailing pond's seepage field and the dam body's permeability stability, which provides a scientific foundation for analyzing and designing the seismic static-dynamic stability of the tailings pond.

River restoration effects on dispersal and the development of riparian seed bank: do poor seed banks limit restoration of boreal riparian zones?

In boreal streams, restoration after channelization typically consists of increasing instream geomorphic complexity with no other active restoration measures (e.g. planting) as it mainly targets fish. Unsurprisingly, this restoration fails to restore riparian vegetation within the time frames needed to meet biodiversity goals. To understand the potential role of dispersal and seed banks in the poor restoration results, we compared deposition patterns from a seed release experiment conducted during spring flood and summer low flow conditions to seed bank‐ and vegetation composition. The experiment was conducted across seven boreal streams, each differing in time since restoration (0–22 years). We found that seed deposition increased due to low flow and local flow obstruction, suggesting the importance of instream boulders. Locations where there was a high deposition likelihood in our seed release experiment had higher Shannon diversity compared to locations with a low seed deposition likelihood. Riparian vegetation composition is related to flow obstruction, while seed bank species composition is correlated to spring flood seed deposition. In general, the sampled riparian seed banks contained few seeds and species. We therefore conclude that (1) restoration of hydrogeomorphic complexity (especially instream boulders) can enhance seed deposition with some effects on species composition of the vegetation and seed bank diversity, and (2) the importance of these generally species poor seed banks for the return of species after restoration boreal streams is questionable. Other (active) methods or more time may therefore be needed to meet biodiversity goals within riparian vegetation restoration.

Characteristic Analysis of Vertical Tidal Profile Parameters at Tidal Current Energy Site

Many mathematical models have been proposed to estimate vertical tidal current profiles. However, as previous studies have shown that tidal current energy sites have different characteristics in their vertical tidal current profiles, it is necessary to estimate the profiles from field-measured data for practical purposes. In this study, we measured layered tidal currents over two months using an acoustic Doppler current profiler (ADCP) to analyze the characteristics of vertical tidal current profiles at the Jangjuk Strait, a candidate site for tidal current energy. As a result, the power law parameter α and bed roughness β were estimated as 4.51–12.41 and 0.38–0.42, respectively. Additionally, the maximum roughness length representing seabed roughness in the logarithmic profile was estimated as 0.221 m, and the estimated friction velocity was 0.038–0.194 m/s. Furthermore, a high correlation was observed between the depth-averaged tidal current velocity and friction velocities at all sites during flood and ebb tide conditions. A high correlation was also found between the bed roughness, roughness length, and power law exponent at relatively deeper sites. Tidal current energy sites display distinct characteristics compared to other sea areas. Therefore, it is essential to account for field conditions when conducting numerical modeling and design.

A novel flood conditioning factor based on topography for flood susceptibility modeling

Flood is one of the most devastating natural hazards. Employing machine learning models to construct flood susceptibility maps has become a pivotal step for decision-makers in disaster prevention and management. Existing flood conditioning factors inadequately account for regional characteristics of flood in the depiction of topography, potentially leading to an overestimation of flood susceptibility in flat areas. Addressing this gap, this study proposes a novel flood conditioning factor, local convexity factor (LCF), to enhance the accuracy of flood susceptibility modeling. Initially, LCF is computed based on a standard normal Gaussian surface to highlight elevation variations in local terrain. Subsequently, LCF is applied to flood susceptibility modeling using seven machine learning models across four distinct basins. Comparative analysis is conducted between flood susceptibility maps with and without the application of LCF to evaluate its impact on flood susceptibility modeling. The results demonstrate that the proposed LCF can enhance the accuracy of flood susceptibility modeling to varying degrees, across the four basins investigated. The Fujiang basin exhibited the most substantial improvement, with its AUC improved from 0.861 to 0.886, Producer’s Agreement improved from 0.869 to 0.899, and Overall Agreement improved from 0.778 to 0.811. Comparation with hydrodynamic inundation maps shows that particularly in relatively flat terrain areas, flood susceptibility maps incorporating LCF offer more precise delineation between flood-prone and non-flood-prone zones. This research holds potential for widespread application in the prediction of flood susceptibility using machine learning models, providing a novel perspective for enhancing their accuracy

Optimal Relationship Between As and Cd in Porewater of Paddy Soils with Variations in pe + pH: Insight from Trade-Off Value Analysis

The remediation of paddy soils co-contaminated with As and Cd is tricky. It is difficult to decrease Cd and As availability simultaneously due to their opposite geochemical characteristics. Finding the optimal trade-off relationship between As and Cd availability in paddy soils is a significant task that is necessary to guide the construction of water management measures. This study investigated the dissolution characteristics of As, Cd, Fe, Mn, DOC, DOM, and various As and Cd fractions in soils via the microcosm system and calculated the optimal trade-off value for available As and Cd in porewater. The results showed that the total As in porewater increased rapidly when the soil Eh was reduced to −104 mV. Meanwhile, the total Cd in porewater decreased dramatically when the soil Eh was below 62 mV. Under flooding and drainage conditions, Fe/Mn (oxyhydro)oxides play a vital role in regulating Cd dissolution in paddy soils, while Fe/Mn (oxyhydro)oxides organically bind sulfide together to determine the dissolution of As. Additionally, the optimal pe + pH response to the minimum trade-off value of available As and Cd in porewater was found to be 6.6, which indicates a moderate reduction status. Therefore, further research should apply the optimal pe + pH to construct water management measures to safely utilize co-contaminated paddy fields.

Mature Tubers of Cyperus rotundus Confer Flooding Tolerance by Adopting A “Low-oxygen Quiescence Strategy”, which may Contribute to Its Emergence in Rice Fields

Abstract Purple nutsedge (Cyperus rotundus L.) is one of the world’s resilient upland weeds, primarily spreading through its tubers. Its emergence in rice fields has been increasing, likely due to changing paddy farming practices. This study aimed to investigate how C. rotundus, an upland weed, can withstand soil flooding and become a problematic weed in rice (Oryza sativa L.) fields. The first comparative analysis focused on the survival and recovery characteristics of growing and mature tubers of C. rotundus exposed to soil flooding conditions. Notably, mature tubers exhibited significant survival and recovery abilities in these environments. Based on this observation, further investigation was carried out to explore the morphological structure, non-structural carbohydrates, and respiratory mechanisms of mature tubers in response to prolonged soil flooding. Over time, the mature tubers did not form aerenchyma but instead gradually accumulated lignified sclerenchyma fibers, with lignin content also increasing. After 90 days, the lignified sclerenchyma fibers and lignin contents were 4.0 and 1.1 times higher than those in no soil flooding (CK). Concurrently, soluble sugar content decreased while starch content increased, providing energy storage, and alcohol dehydrogenase (ADH) activity rose to support anaerobic respiration via alcohol fermentation. These results indicated that mature tubers survived in soil flooding conditions by adopting a “low-oxygen quiescence strategy”, which involves morphological adaptations through the development of lignified sclerenchyma fibers, increased starch reserves for energy storage, and enhanced anaerobic respiration. This mechanism likely underpins the flooding tolerance of mature C. rotundus tubers, allowing them to endure unfavorable conditions and subsequently germinate and grow once flooding subsides. This study provides a preliminary explanation of the mechanism by which mature tubers of C. rotundus from the upland areas confer flooding tolerance, shedding light on the reasons behind this weed’s increasing presence in rice fields.

Road network disruptions during extreme flooding events and their impact on the access to emergency medical services: A spatiotemporal vulnerability analysis

The impact of extreme floods can be significant, affecting humans, the environment and any type of human-built infrastructure. A further consequence of flooding is restricted access to medical facilities, including constraints to access more dedicated emergency medical services (EMS). To date, there has been a lack of investigation into EMS accessibility dynamics during extreme floods. The objective of this study is to gain a deeper understanding of the spatiotemporal changes in accessibility-based vulnerability related to EMS during a representative extreme flood event, which was simulated over a period of six days. The study assesses the spatial accessibility of EMS centres to populations located within 15-, 30-, 45-, and 60-minute travel time thresholds in Canton Bern, Switzerland, and applies floating catchment area method. The dynamic aspects of EMS access vulnerability during extreme floods were assessed in two different ways. Firstly, the ratios between accessibility change and accessibility under normal conditions in 1 km grid cells were calculated at hourly moments, t. Subsequently, the resulting values were used to calculate the average vulnerability score. Secondly, percentage changes of affected populations were evaluated for different accessibility classes during the flood event and under all-time high static flood conditions. Varied spatial patterns of accessibility were generally observed with respect to the road network and population distributions in the hilly and mountainous landscape. Extending evaluations to consider temporal dynamics revealed a complex pattern of accessibility gains and losses in different regions of the study area, including those where no direct flood impacts occurred on the road network. The application of a static, all-time high flood condition resulted in an overestimation of accessibility limits to EMS centres. While this overestimation was not considered to be critical, the application of a spatiotemporal accessibility-based vulnerability analysis method to EMS is considered to be more holistic. Insights from this study can be used to evaluate the effectiveness of EMS risk management plans with respect to evolving extreme flood scenarios.

Levee Soil Stratification Based on PAM Cluster Analysis of Measured Soil Samples from Multiple Probe Drilling Sites

Accurate soil stratification is crucial for levee safety evaluation, yet limited field sampling often hinders comprehensive analysis. This study applies the Partitioning Around Medoids (PAM, also known as K-Medoids) clustering approach for levee soil stratification using data from multiple probe drilling sites. Focusing on a Yellow River levee section in China as a study case, the PAM clustering approach effectively identifies its distinct soil types and reconstructs its soil stratification by analyzing key soil properties relevant to levee seepage and stability characteristics, including coefficient of permeability, angle of internal friction, and cohesion. The resulting soil stratification, when applied to seepage and stability analyses of the levee section, yields relatively high safety factors, indicating low failure risks under design flood conditions. These analytical results align with recent monitoring records, validating the effectiveness of the approach. A sensitivity analysis on the number of clusters, the key parameter in the PAM clustering approach, demonstrates the typical existence of an optimal value balancing computational accuracy and practical interpretability. A comparison with a hierarchical clustering approach further confirms the robustness of the PAM clustering approach. This study contributes to improving levee soil stratification methodology and enhancing levee safety evaluation, particularly when dealing with limited and spatially distributed sampling data.

Assessing the impact of a large multi-purpose reservoir on flood control under moderate and extreme flood conditions

ABSTRACT This study offers a detailed examination of the Eupen dam’s role in flood mitigation in Belgium’s Vesdre valley, analysing 18 moderate and extreme flood events from 1995-2022. Notable aspects of the methodology include adjustments for an ungauged sub-basin and a mass-balance approach to compute the unknown outflow data from the inflow time-series and reservoir level data. These 18 events evidence the dam’s performance hitherto, with respect to peak discharge attenuation (9-91%), peak delay (0-68 hours), outflow volume reduction (2-94%), as well as discharge reductions associated with various return periods (38-51%), given its multipurpose objectives. The research details how the dam’s effectiveness varies with operational decisions and antecedent reservoir conditions, marking a departure from conventional studies that tend to generalise data across multiple dams and events. By focusing on individual events, the study provides insights into the nuanced interplay between dam operations and flood management, demonstrating the benefits and limitations of multi-purpose reservoirs in flood control.

Impact of flooding at the early reproductive growth stage on soybean yield and seed composition

AbstractFlooding stress is a growing threat to global soybean [Glycine max (L.) Merr.] production as the frequency and intensity of extreme precipitations are increasing due to climate change. Soybean is highly sensitive to flooding and substantial yield losses are observed due to a cascade of negative physiological responses induced by hypoxia. Hence, there is a pressing need for the development of flood‐tolerant genotypes. This study evaluated the grain yield and seed protein and oil content of 31 soybean genotypes over 2 years under both non‐flooding and flooding conditions, where flooding entailed a 4‐day partial water submergence during the early reproductive growth stages R1/R2. Mixed‐effects linear models were utilized to assess the impact of flood damage scores (FDSs, 1–4 scale) on observed phenotypes, as well as differences in observed phenotypes between tolerant, moderate, and susceptible genotypes across flooding and non‐flooding treatments. No significant impact of FDS was observed for seed protein and oil content. In addition, no significant differences in these phenotypes were observed between flooding and non‐flooding treatments across the various genotype categories. On average, for each unit increase in FDS, grain yield decreased by 432.7 kg ha−1 (17.4%). Tolerant genotypes experienced roughly 33% yield losses between flooding and non‐flooding treatments, while moderate and susceptible genotypes experienced 44% and 51% yield losses, respectively. The advancements in genomics and phenomics are promising for the identification and incorporation of novel flood‐tolerant alleles through plant breeding, potentially mitigating flooding‐induced yield losses across diverse environmental conditions.

Comparison of Nitrous Oxide Consumption of Paddy Soils Developed from Three Parent Materials in Subtropical China

Paddy soils developed from various parent materials are widely distributed in the subtropical region in China and have a non-negligible but unclear potential to consume nitrous oxide (N2O) due to long-term flooding. This study selected three of the most common paddy soils in subtropical China, developing from quaternary red soil (R), lake sediment sand (S), and alluvial soil (C), to study their total N2O consumption and total nitrogen (N2) production using N2-free microcosm experiments. These paddy soils were treated with N2O addition (N2O treatment) or helium (He) addition (CK treatment) and incubated under flooding and anoxic conditions. The results showed that three alluvial soils (C1, C2, and C3) consumed over 99.93% of the N2O accumulated in the soil profile, significantly higher than R and S soils (p < 0.05). And the N2 production in three C soils was also significantly higher than other soils, accounting for 81.61% of the total N2O consumption. The main soil factors affecting N2O consumption in C, S, and R soils were soil clay content (p < 0.05), soil sand content (R2 = 0.95, p < 0.001), and soil available potassium (AK) (p < 0.01), respectively. These results indicate flooding paddy soils, no matter the parent materials developed, could consume extremely large amount of N2O produced in soil profiles.

Physiological and Transcriptomic Analyses Reveal the Role of the Antioxidant System and Jasmonic Acid (JA) Signal Transduction in Mulberry (Morus alba L.) Response to Flooding Stress

In recent decades, the frequency of flooding has increased as a result of global climate change. Flooding has become one of the major abiotic stresses that seriously affect the growth and development of plants. Mulberry (Morus alba L.) is an important economic tree in China. Flooding stress is among the most severe abiotic stresses that affect the production of mulberry. However, the physiological and molecular biological mechanisms of mulberry responses to flooding stress are still unclear. In the present study, reactive oxygen species (ROS) metabolism, antioxidant mechanism, and plant hormones in mulberry associated with the response to flooding stress were investigated using physiological and transcriptomic analysis methods. The results showed significant increases in the production rate of superoxide anion (O2•−) and the content of hydrogen peroxide (H2O2) in leaves on the 5th day of flooding stress. This led to membrane lipid peroxidation and elevated malondialdehyde (MDA) levels. Antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) exhibited enhanced activities initially, followed by fluctuations. The ascorbic acid–glutathione (AsA-GSH) cycle played a crucial role in scavenging ROS, promoting the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH). Transcriptomic analysis revealed the up-regulation of the gene-encoding antioxidant enzymes (APX, MDHAR, GPX, GR, GST) involved in ROS scavenging and stress tolerance mechanisms. Jasmonic acid (JA) levels and the expression of JA synthesis-related genes increased significantly in mulberry leaves under flooding stress. This activation of the JA signaling pathway contributed to the plant’s adaptability to flooding conditions. Proline (Pro) and soluble sugar (SS) contents increased notably in response to flooding stress. Proline helped maintain cell turgor and protected enzymes and membranes from damage, while soluble sugars supported anaerobic respiration and energy supply. However, soluble protein (SP) content decreased, suggesting inhibition of protein synthesis. The study provides insights into mulberry’s flooding tolerance mechanisms, guiding future molecular breeding efforts. This summary captures the key findings and implications of the study on mulberry’s response to flooding stress, focusing on physiological and molecular mechanisms identified in the research.

Integrated urban and riverine flood risk management in the Fujiang River Basin-Mianyang city

China’s monsoon climate, characterized by hot summers and substantial rainfall, leads to significant seasonal water accumulation in river basins. This often results in short-term heavy rainfall events, causing rapid water flow into river basins and subsequent flooding. River embankments, which narrow channels, exacerbate downstream flooding and pose severe safety threats. This study explores integrated urban and riverine flood risk management strategies within the Fujiang River Basin, focusing on Mianyang City. The research addresses the growing challenges of global climate change and rapid urbanization, which have intensified flood risks. Utilizing the one-dimensional Storm Water Management Model (SWMM) and two-dimensional hydrodynamic Rainfall-Runoff-Inundation (RRI) model, the study simulates flood events and urban flooding in Mianyang City and the Fujiang River Basin. These models were validated with data from hydrological stations and satellite imagery. The study evaluates extreme flood events in Mianyang City between 2015 and 2021. The findings highlight the significant role of sponge city initiatives and low-impact development (LID) facilities in mitigating flood impacts. Despite their benefits, these measures have limitations under extreme flood conditions. This study contributes to understanding the interactions between urban and riverine systems and provides a basis for improving flood risk management and resilience in rapidly urbanizing river basins. It supports ongoing efforts to implement sponge city concepts in China, offering crucial insights into effective strategies for managing flood risks in similar geographic and climatic contexts.

Resistance of Australian fish communities to drought and flood: implications for climate change and adaptations

Climate change‐induced extreme weather and related drought and flood conditions are heterogeneous across space and time. The variability in location, timing, and magnitude of rainfall can alter how species respond to the drought and flood disturbances. To further complicate this matter, when droughts end they are often followed by extreme flooding, which are rarely considered as a disturbance (Humphries et al. 2024), let alone assessed with its own heterogeneity. Consequently, it is difficult to quantify impacts on ecological communities across large spatiotemporal scales without considering flood‐drought disturbance characteristics in sequence (Burton et al. 2020). We hypothesized that native organisms have evolved resistance to withstand repeated cycles of drought‐flood disturbances, and that established non‐native species have adapted to persist in novel conditions. To test this, we fit spatiotemporal models of species occurrence with local rainfall patterns as covariates in the drought and flood impacted Murray‐Darling basin in Australia during the decade long Millenium Drought, and its recovery period. During these drought conditions, river‐floodplain organisms in the Murray‐Darling became localized in refugia that limited longitudinal and lateral connectivity (Bond et al. 2008), and following flooding the same organisms were exposed to dispersal and recruitment opportunities (Humphries et al. 2020), as well as to hypoxic blackwater events that lead to the mortality of aquatic organisms (Small et al. 2014). At the basin‐scale we found that the range size of most native and non‐native fishes were highly resistant to the extreme drought and post‐flood conditions. At local scales, species richness, or detection, actually increased under drought conditions. Both findings highlight the resistance of species to climate change driven extreme weather, which opens new questions on community adaptations.

Flood risk assessment under the shared socioeconomic pathways: a case of electricity bulk supply points in Greater Accra, Ghana

This study evaluates flood susceptibility and risk on Bulk Supply Points in the Greater Accra region (GAR) using a Frequency Ratio model based on 15 flood conditioning factors. The model explores the influence of natural, meteorological and anthropogenic factors on flooding occurrences under the Shared Socioeconomic Pathway (SSP) scenarios and assesses flood risks at Bulk Supply Points (BSPs). Flood susceptibility mapping was conducted for both current and future periods under various SSP scenarios. Results reveal that elevation, slope, soil type, distance from urban areas, and SPI are the most influential factors contributing to flooding susceptibility in the region. The current flood map, about 37% of the total area of GAR categorized under the moderate flood-susceptible zone category followed by about 30% categorized under the low flood-vulnerable zone. However, about 16% was categorized under the very high flood-vulnerable zone. The study projects increasing flood susceptibility under the SSP scenarios with intensification under SSP2 and SSP3 scenarios. For instance, the areas categorized as high and very high flood susceptibility zones are projected to expand to approximately 32% and 26% each by 2055 under SSP3. The study also assesses flood risks at Bulk Supply Points (BSPs), highlighting the escalating susceptibility of power assets to flooding under different scenarios. For instance, in the very high scenario, flooding is estimated to reach 640 h in 2045 and exceed 800 h in 2055—more than double the 2020 baseline. The analysis shows the bulk supply points face increasing flood susceptibility, with risks escalating most sharply under the severe climate change SSP3 and SSP5 scenarios. Over 75% of BSPs are expected to fall in the low- to medium-risk categories across SSPs while more than 50% of BSPs are within medium- to high-risk categories in all scenarios except SSP1, reflecting the impact of climate change. SSP3 and SSP5 stand out with over 60% of BSPs facing high or very high flooding risks by 2055. It indicates moderate resilience with proper adaptation but highlights potential disruptions in critical infrastructure, such as BSPs, during persistent flooding. The findings of the study are expected to inform Ghana’s contributions towards addressing Sustainable Development Goals (SDGs) 7, 11 and 13 in Ghana.

A dataset of floating debris accumulation at bridges after July 2021 flood in Germany and Belgium

This paper presents a dataset documenting 71 floating debris accumulations at bridges following an extreme hydrological event that hit Belgium and Germany in July 2021. Data were collected from various sources including public authorities’ documents, public online databases, post event pictures and field visits. The dataset covers bridges geometry, flood conditions and debris accumulation. In particular, it systematically details accumulations dimensions and quantifies accumulations components, which contain a significant portion of anthropogenic objects, in addition to driftwood. This dataset constitutes a unique set of invaluable data to better understand debris accumulation at bridges but also to analyze their impact on both the affected structures and flood conditions.

Flood Risks Analysis in Upton Upon Severn: Assessing the Baseline Conditions and Future Scenarios for 100 and 1000-year Flood Events with a 2050 Climate Change Perspective.

This paper investigates the flood risks in Upton upon Severn, a town in Worcestershire, England, which is prone to fluvial flooding from the River Severn. Historical events, such as the significant floods of 1947 and 2007, highlight the town’s vulnerability and underscore the importance of analysing current and future flood risks. This research uses a one-dimensional hydraulic model, using Flood Modeller and QGIS software, to assess baseline flood conditions and predict the potential impacts of severe and extreme flood events, including 1 in 100-year and 1 in 1000-year flood scenarios. Additionally, it examines the projected effects of climate change by incorporating a 20% increase in flood risk estimates for the year 2050. The model results reveal that the baseline scenario poses limited flood risks, with only 17 properties affected, and key infrastructure like the A4104 road remains passable. However, under the 1 in 100-year event, approximately 336 properties are at risk, with significant road blockages and a flooded area of 5.09 Km2. The 1 in 1000-year flood scenario predicts a peak flow of 1807 m3/s, threatening more properties and covering a larger area of land. When climate change is factored into the 1 in 100-year scenario, the risks become similar to those of the 1 in 1000-year event, with 500 properties and key infrastructure, including the fire station and primary school, at risk and the A4104 road becoming impassable. These findings provide vital insights for flood risk management, especially given the possible effects of climate change, and stress the need for long-term solutions to flooding.

Aging of biodegradable microplastics and their effect on soil properties: Control from soil water

The ecological risks of biodegradable microplastics (BMPs) to soil ecosystems have received increasing attention. This study investigates the impacts of polylactic acid microplastics (PLA-MPs) and polybutylene adipate terephthalate microplastics (PBAT-MPs) on soil properties of black soil (BS) and fluvo-aquic soil (FS) under three water conditions including dry (Dry), flooded (FL), and alternate wetting and drying (AWD). The results show that BMPs exhibited more evident aging under Dry and AWD conditions compared to FL condition. However, BMPs aging under FL condition induced more substantial changes in soil properties, especially dissolved organic carbon (DOC) concentrations, than under Dry and AWD conditions. BMPs also increased the humification degree of soil dissolved organic matter (DOM), particularly in BS. Metagenomic analysis of PBAT-MPs treatments showed different changes in microbial community structure depending on soil moisture. Under Dry conditions, PBAT-MPs enhance the ammonium-producing process of soil microbial communities. Genes related to N nitrification and benzene degradation were enriched under AWD conditions. In contrast, PBAT-MPs do not change the abundance of genes related to the N cycle under FL conditions but significantly reduce genes related to benzene degradation. This reduction in benzene degradation genes under FL condition might potentially slow down the degradation of PBAT-MPs, and could lead to temporary accumulation of benzene-related intermediates. These findings highlight the complex interactions between BMPs, soil properties, and microbial communities, emphasizing the need for comprehensive evaluations of BMPs’ environmental impacts under varying soil water conditions.

Machine learning-based rainfall forecasting in real-time optimal operation of urban drainage systems

This paper presents a rainfall forecast-based real-time optimal operation model of urban drainage systems (UDSs) investigating the role of rainfall forecasts in predictive real-time operation of UDSs. Two rainfall forecast models, namely long short-term memory (LSTM) and optimized-by-PSO (particle swarm optimization) support vector regression, are linked to an integrated simulation–optimization model. For any given operation policies, the rainfall-runoff stormwater management model (SWMM) simulates the urban system’s operation under flooding conditions in which the operation policies are optimized by the metaheuristic harmony search (HS) optimizer. The objective function of the HS algorithm is minimizing flood volumes at control points. The presented approach is therefore a dynamic predictive real-time operation (PRTOP) model that continuously updates rainfall forecasts and operational decisions during flood events. The performance of the developed forecast-based integrated SWMM-HS simulation–optimization modeling framework is tested through its application in a real urban system case study located in Tehran, Iran. Results demonstrate that a notable reduction in flood volume (11.8%) is achieved by using the LSTM-driven rainfall forecasts in the proposed PRTOP model compared to a reactive real-time operation (RTOP) model not utilizing rainfall forecasts.

Salinity increases under sea level rise strengthens the chemical protection of SOC in subtropical tidal marshes

The rise in sea levels due to global warming could significantly impact the soil organic carbon (SOC) pool in coastal tidal marshes by altering soil salinity and flooding conditions. However, the effects of these factors on SOC protection in coastal tidal marshes are not fully understood. In this study, we employed a space-for-time approach to investigate the variations in soil active carbon components and mineral-associated organic carbon under different salinity gradients (freshwater and brackish) and flooding frequencies (high and low tidal flats).The soil organic carbon (SOC) and easily oxidizable organic carbon (EOC) contents at the low-flooding frequency sites were higher than those at the high-flooding frequency sites. The dissolved organic carbon (DOC) content was higher at the high-salinity sites compared to the low-salinity sites, while the soil microbial biomass carbon (MBC) content was higher at the low-salinity sites than at the high-salinity sites. The EOC/SOC and DOC/SOC ratios were greater at the high-salinity sites than at the low-salinity sites, whereas the MBC/SOC ratios were higher at the low-salinity sites than at the high-salinity sites. Iron (Fe) and aluminum (Al) mineral-associated organic carbon [Fe(Al)-OC] and calcium-associated organic carbon (Ca-OC) contents were higher at the high-salinity sites compared to the low-salinity sites, and at the low-flooding frequency sites compared to the high-flooding frequency sites.Meanwhile, Fe(Al)-OC was the dominant fraction among mineral-associated organic carbon at all sites. The dominant phyla of bacterial community included Proteobacteria (49.31 %–66.36 %), Firmicutes (2.67 %–28.44 %), Chloroflexi (3.81 %–9.54 %), and Acidobacteria (4.28 %–7.02 %). In addition, Desulfobacca, a sulfate-reducing bacterium, promoted the formation of mineral-associated organic carbon.Random forest analysis showed that SOC and DOC were key factors in promoting mineral-associated organic carbon formation. Partial least squares path modeling (PLS-PM) indicated that sea level rise affects DOC content by altering soil physicochemical properties, promoting the formation of mineral-associated organic carbon.In summary, while soil organic carbon activity increases, the chemical association of minerals with organic carbon is becoming increasingly crucial for the protection of organic carbon under rising salinity conditions driven by sea level rise.