Water Level Fluctuations Research Articles

Ecological Dynamics and Conservation Strategies for Mediterranean Salt Marshes: Insights from a Pilot Study of Biodiversity and Environmental Drivers in the Palud Marsh, Croatia

Salt marshes support high biodiversity and provide essential ecosystem services, yet are increasingly threatened by climate change, reduced freshwater input, and human activities. This pilot study examined the physico-chemical characteristics and biodiversity of the Palud salt marsh in Istria, Croatia, during July 2021, focusing on phytoplankton, zooplankton, and macrozoobenthos communities across different habitats. The results show that while parameters like water temperature and pH remained stable, dissolved oxygen and nutrient levels fluctuated significantly. Water depth decreased due to drought and tidal oscillations, affecting salinity and nutrient concentrations. Phytoplankton communities were dominated by Bacillariophyta, with Cryptophyta, particularly Cryptomonas sp., having the highest abundance. Zooplankton communities were dominated by Rotifera, especially Brachionus plicatilis, while the macrozoobenthos communities were dominated by Ostracoda, with some variation in gastropod and chironomid abundance across sites. These findings indicate the dynamic nature of plankton and benthos communities in response to changing water levels in the Palud marsh. This study highlights the need for targeted conservation strategies to preserve the ecological integrity of Mediterranean salt marshes. Sustainable management practices must account for water level fluctuations, the role of aquatic vegetation, and the resilience of these ecosystems, emphasizing their importance in supporting biodiversity and ecosystem services in the face of environmental change.

설악산국립공원 주변 지하수관측망의 수위변동 해석

To understand the water level fluctuation characteristics at the groundwater observation network installed and operated in the area around Seoraksan National Park, a time series analysis of long-term data of groundwater levels observed in the network from 2012 to 2021 was performed. The observation network comprises three locations, all installed in the bedrock aquifer, and periodic inspections and management are carried out by the relevant operating agency. According to the linear analysis results, the groundwater level decreased by -89.7 cm/yr at the Goseong-Inheung Observatory, whereas it rose by 3.7 cm/yr at the Goseong-Toseong Observatory. A strong autocorrelation was observed among the three observatories. In particular, at the Goseong-Inheung Observatory, the time delay was found to be approximately 8 times longer than that at the Goseong- Toseong and Sokcho-Nohak observatories, whereas the time delay of precipitation was similar to the time delay of Goseong-Toseong and Sokcho-Nohak. These results were judged to have strong linearity and memory effects with the groundwater level data. Analysis of the cross-correlation function between rainfall and groundwater levels showed that Goseong-Inheung had a certain degree of cross-correlation with rainfall, with a delay of 12 days. If the discharge in major rivers of Seoraksan National Park is continuously monitored, researches on water resources using river discharge and groundwater levels are expected to be actively conducted.

Simulation and prediction of sulfamethazine migration, transformation and risk diffusion during cross-media infiltration from surface water to groundwater driven by dynamic water level: Machine learning coupled HYDRUS-GMS model

Seasonal water level fluctuations in rivers significantly influenced the cross-media migration, transformation, and risk diffusion of antibiotics from the vadose zone into groundwater. This study developed a coupled model integrating machine learning (ML) with HYDRUS-3D and GMS to accurately predict sulfamethazine migration under dynamic water levels. The predictive accuracy (E≥0.98) of this ML-HYDRUS-GMS model was enhanced by accounting for seasonal water level fluctuations and biogeochemical variability. Significant seasonal differences presented with sulfamethazine diffusion in the vadose zone with the migration rate decreased from 0.06 m/d to 0.02 m/d with the transition from wet to dry seasons. After 6 years of infiltration, it reached groundwater, where lateral migration rates, influenced by seasonal flow variations, were 0.12 m/d in the wet season and decreased to 0.07 m/d in the dry season, with a diffusion range extending to 217 m over 100 years. This discrepant continuous filtration of sulfamethazine and the succession of metabolic pathways induced toxicity range to expand by 65.6 m and the risk to increase to warning level. Sulfamethazine underwent oxidative breakdown in aerobic vadose zone conditions, while anaerobic groundwater conditions led to hydrogenation and reduction, increasing its migration distance.

Macrophyte species composition and abundance of hydrogeologically connected wetlands in upper Abbay river basin, Ethiopia

Macrophytes are key components of aquatic ecosystems including wetlands that have considerable ecological importance. The role of macrophytes is closely linked to their structural attributes like species composition and abundance. Therefore, this study aimed to assess macrophyte species composition, abundance and diversity of six hydrogeologically connected wetlands in the upper Abbay River basin, Ethiopia. The studied wetlands (Gudera, Geray, Zindib, Kurt Bahir, Infranz and Wonjeta) are found in west Gojjam administrative zone, Amhara region, Ethiopia. Two cross-sectional surveys were conducted at the end of September 2021 and February 2022. Quadrat sampling technique was employed to collect macrophyte samples following protocols for sampling aquatic macrophytes in freshwater wetlands. A total of 41 species of macrophytes belonging to 16 families were identified across the wetlands. The wetlands were dominated by emergent macrophytes, with the Poaceae and Cyperaceae families being particularly abundant. The physicochemical water quality status, water level fluctuations and level of human interventions might be the reason for the variation in the macrophytes composition, abundance and diversity across the wetlands. The low macrophyte diversity index value and the presence of pollution-tolerant taxa such as Pistia stratiotes and Azolla africana indicate an overall ecological degradation of the wetlands. Therefore, this study highlights the potential role of macrophyte monitoring to identify anthropogenic pollution. Application of appropriate land use planning and the development of macrophyte based multimetric indices are recommended for their sustainable management.

Within-lake isolation and reproductive strategy of Stuckenia pectinata (L.) Börner at Lake Naivasha (Kenya): About water level fluctuations and alien species

Submerged aquatic plants with mixed reproduction mode may show enhanced clonal growth explained by environmental conditions. For Stuckenia pectinata (L.) Börner this has been linked to within-lake factors, both biotic (tuber predation, herbivory, periphyton shading) and abiotic (hydrological connectivity, sediment type). We investigated the S. pectinata population from Lake Naivasha, where submerged aquatic plants tolerated strong historical water level fluctuations until introduced crayfish, shading by floating exotic weeds and increased turbidity nearly eradicated them, although some stands now rebounded in various lake areas. Using 13 nuclear microsatellite loci, we analyzed genetic diversity and structure of S. pectinata subpopulations along the southeastern shoreline of the main lake and inside Crescent Island Crater, a peripheral lake basin enclosed within the rim of an extinct volcano. Results revealed a predominantly sexual reproductive strategy with limited clonal expansion in the main lake contrasting with pronounced clonal growth in the crater basin. Each subpopulation experienced recent bottlenecks. Crater basin subpopulations exhibited the strongest divergence, lower clonal diversity and larger-sized clones. We explain this differentiation by the exposed crater rim acting as barrier, isolating the crater basin from the main lake during recent decades when low water levels prevailed, accompanied with less negative impact from alien species than in the main lake. Clonal extension occurred on steep-sloping hard sandy substrates, that likely prompted local reproductive adaptations. Genetic diversity, clonal structure and connectivity patterns are discussed in the light of the specific history and features of Lake Naivasha.

The Influence of Short-Term Water Level Fluctuations on the Habitat Response and Ecological Fragility of Siberian Cranes in Poyang Lake, China

The landscape of the Poyang Lake wetland is significantly influenced by changes in water levels, impacting the distribution of habitats for migratory birds. While long-term effects of water level variations have been extensively studied, short-term impacts on Siberian crane habitats and their ecological vulnerability remain poorly understood. This study utilized 35 years (1987–2022) of Landsat remote sensing data and daily water level records from Poyang Lake to examine the effects of short-term water level fluctuations on the spatial distribution and ecological vulnerability of Siberian crane habitats. The geographic detector method was employed to quantify the explanatory power and interaction effects of factors, including short-term water level fluctuations, on ecological vulnerability. The findings reveal significant differences in the habitats of wintering Siberian cranes across various water level intervals and short-term fluctuation patterns. Short-term water level fluctuations can result in the largest suitable wintering habitat area for Siberian cranes, reaching 1856.41 km2 in this study. These habitats are highly sensitive to short-term water level changes, with rising and falling trends potentially leading to habitat loss. Oscillating water levels in the short term create broader and more concentrated habitats. Notably, fluctuations at low water levels support the sustainability and stability of crane habitats. Furthermore, short-term water level trends and nature reserves play a critical role in maintaining habitat ecological vulnerability; well-managed and protected nature reserves exhibit significant explanatory power, both in single-factor analysis and in their interaction with other environmental factors. Specifically, these protected areas show explanatory power exceeding the 20% threshold for both water level fluctuations and ranges, highlighting the crucial role of anthropogenic management in mitigating ecological vulnerability. This study emphasizes the necessity of scientifically informed regulation of short-term water level fluctuations to protect Siberian crane habitats and provides a strong scientific basis for decision-making support.

Heterogeneous long-term and seasonal brine evolution, and Artemia fecal pellet controls on Urmia Lake (NW Iran) salt-crust formation and mineralogy

ABSTRACT Urmia Lake resides as a substantial hypersaline lake characterized by notable fluctuations in water salinity, brine composition, and water level over long-term, annual, and seasonal intervals. Extremely rapid water elevation fall (> 7 m) in the last three decades has caused the formation of a salt crust on the lake floor. A manmade stone causeway divided the lake into two relatively deeper northern parts with minimal water inputs and a shallower southern part with maximal river inflows. Restricted water flow through the narrow water passage of the causeway leads to complex salinity processes, brine evolution, and salt-crust formation in Urmia Lake. This research analyzes the ionic composition of lake-sediment and salt-crust pore water, the mineralogy of salt crusts, and the ionic composition of both surface and deep lake waters during both the wet and dry seasons of 2019. The findings indicate that the northern and southern parts of the lake undergo stratification during wet seasons due to significant freshwater input, whereas they become homogenized during dry seasons through progressive evaporative concentration and water mixing. The spatial and temporal variations in the lake brine type (primary Na-Mg-Cl) and ionic composition contribute to the formation of a halite salt crust (NaCl > 97%) with heterogeneous mineralogy and thickness. In Urmia Lake, the variable thickness and mineralogy of the exposed marginal salt crust suggest rapid salt-crust reorganization by annual and seasonal deposition and dissolution processes. Conversely, the submerged central salt crust, with continuous thickening and constant mineralogy, remains unaffected by seasonal variations in brine type and dissolution processes. It is noteworthy to mention that Artemia (a brine shrimp) controls the mineralogy of the lake salt crust through the deposition of calcium and carbonate ions in the form of biochemical fecal pellets.

The patterns and controlling factors of soil carbon and nitrogen in the water level fluctuation zone of the Three Gorges Reservoir

The patterns and controlling factors of soil carbon and nitrogen in the water level fluctuation zone of the Three Gorges Reservoir

The Floating Urbanism of Cambodia’s Tonlé Sap

For decades, the floating villages of Tonlé Sap, a lake in Cambodia, have demonstrated ingenuity by necessity and adaptability to the seasonal rhythms of nature. The villages are examples of ephemeral, floating urbanism, a response to discriminatory land tenure practices that is able to adjust to ever-increasing fluctuations in water levels exacerbated by global warming. The villages’ Indigenous knowledge systems and practices (IKSP) display a distinct intelligence, in which water-based modes of living and livelihoods are connected with a resourceful understanding and use of locational assets. Conducting intensive fieldwork by boat and living in the floating villages for ten days in August 2023, the authors gained knowledge of local expertise through observation and informal interviews. They documented livelihoods and modes of settlement that suggest a pause in the neo-liberal market-driven globalism sweeping Cambodia. Here they relate their research to existing literature and studies (primarily ethnographic and policy-oriented) of the region’s unique monsoon culture of floating villages with a culturally specific identity that combines hierarchy and heterarchy.

Extreme drought shapes the gut microbiota composition and function of common cranes (Grus grus) wintering in Poyang Lake.

Extreme weather events driven by climate change profoundly affect migratory birds by altering their habitats, food sources, and migration routes. While gut microbiota is believed to play a role in helping birds adapt to environmental changes, research on how extreme weather impacts their gut microbiota and how these microbial communities respond to such conditions has been limited. 16S rRNA gene sequencing was utilized to investigate the gut microbiota of common cranes (Grus grus) wintering at Poyang Lake from 2020 to 2023, with a particular focus on their response to extreme drought conditions on both inter-annual and monthly timescales. The results revealed that extreme drought conditions substantially impact gut microbiota, with inter-annual water-level fluctuations exerting a more pronounced impact on microbial community structure than that of inter-monthly fluctuations. Notably, a significant decline in bacterial diversity within the gut microbiota of common cranes was observed in the extreme drought year of 2022 compared with other years. Monthly observations indicated a gradual increase in gut microbial diversity, coinciding with relatively minor water-level changes. Key taxa that responded to drought included the Enterobacteriaceae family and Bifidobacterium and Lactobacillus species. Additionally, functional genes related to carbohydrate metabolism, the phosphotransferase system, and the two-component systems were significantly enriched during the extreme drought year. These functions may represent adaptive mechanisms by which the gut microbiota of common cranes respond to drought stress. This research provides novel insights into the temporal variability of gut microbiota in wintering waterbirds, underscoring the significant impact of climatic fluctuations on microbial communities. The findings highlight the importance of understanding the ecological and functional responses of gut microbiota to extreme weather events, which is crucial for the conservation and management of migratory bird populations in the face of climate change.

Mechanical properties and energy evolution law of marble under the coupled effects of chemical corrosion and dry-wet cycles.

The main factors affecting the safety of underground structures are groundwater chemical corrosion and water level fluctuations. To investigate the mechanical properties of marble and the energy evolution pattern during the failure process under the coupled effects of chemical corrosion and dry-wet cycling, samples were subjected to 5, 10 and 20 cycles of dry-wet ageing in chemical solutions with pH values of 4, 7 and 10, respectively, followed by mechanical property testing. The energy evolution pattern during the failure process of the specimens was also studied. It was found that there is a strong correlation between number of dry-wet cycles and pH value of chemical solution. Chemical corrosion at the early stage of dry-wet cycling has the greatest effect on the deterioration of the rock. As the number of dry-wet cycles increases, the degree of corrosion in acidic solutions is most evident, with the uniaxial compressive strength and elastic modulus decreasing by 27.88% and 33.52% respectively, followed by alkaline solutions, and the degree of corrosion in neutral solutions is the lowest. In addition, dry-wet cycling and chemical corrosion lead to an increase in the internal pores of the rock samples and a decrease in the energy storage capacity. Nevertheless, the proportion of energy loss increases with the number of dry and wet cycles, with the proportion of energy loss in acidic media increasing from 35.61% to 41.63%, indicating that the plastic deformability of marble increases under the action of chemical corrosion and dry and wet cycles. The research results have certain guiding significance for the design, construction and maintenance reinforcement of underground structures under the conditions of chemical corrosion and dry-wet cycling.

Application of the Bruun rule in evaluating the effect of water level fall on the Caspian Sea profile evolution

ABSTRACT The combined effects of climate change and anthropogenic activities induce significant sea-level alterations, changing beach morphologies. While the effects of water level rise on coastal regions have been extensively studied, the consequences caused by water level fall, particularly in enclosed water basins, have received limited attention. The Bruun rule is an empirical approach for estimating the erosion of sandy beaches in response to sea level rise. This study evaluates the efficacy of the Bruun rule and associated methods under water-level fall conditions. An extensive investigation was followed to understand Bruun’s rule application and its hypotheses in this context. Cross-shore profiles were collected from three stations: Larim, Farahabad, and Miankaleh, located along the southeastern coast of the Caspian Sea between 2013 and 2021. Results indicate that Bruun’s predictions are more reliable, considering their accuracy and applicability. Additionally, active zone bed slope emerges as the most significant factor influencing Bruun prediction, performing well with slopes between 0.013 and 0.016. Moreover, Bruun’s hypotheses were assessed by comparing the observed profiles and water levels over 7 months, 2 years, and 3 years, revealing a lag time contradicting Bruun’s hypothesis. Results further indicate that the Bruun rule overlooks the impacts of water level fluctuations.

Vegetation and carbon sink response to water level changes in a seasonal lake wetland.

Water level fluctuations are among the main factors affecting the development of wetland vegetation communities, carbon sinks, and ecological processes. Hongze Lake is a typical seasonal lake wetland in the Huaihe River Basin. Its water levels have experienced substantial fluctuations because of climate change, as well as gate and dam regulations. In this study, long-term cloud-free remote sensing images of water body area, net plant productivity (NPP), gross primary productivity (GPP), and Fractional vegetation cover (FVC) of the wetlands of Hongze Lake were obtained from multiple satellites by Google Earth Engine (GEE) from 2006 to 2023. The trends in FVC were analyzed using a combined Theil-Sen estimator and Mann-Kendall (MK) test. Linear regression was employed to analyze the correlation between the area of water bodies and that of different degrees of FVC. Additionally, annual frequencies of various water levels were constructed to explore their association with GPP, NPP, and FVC.The results showed that water level fluctuations significantly influence the spatial and temporal patterns of wetland vegetation cover and carbon sinks, with a significant correlation (P<0.05) between water levels and vegetation distribution. Following extensive restoration efforts, the carbon sink capacity of the Hongze Lake wetland has increased. However, it is essential to consider the carbon sink capacity in areas with low vegetation cover, for the lakeshore zone with a higher inundation frequency and low vegetation cover had a lower carbon sink capacity. These findings provide a scientific basis for the establishment of carbon sink enhancement initiatives, restoration programs, and policies to improve the ecological value of wetland ecosystem conservation areas.

Investigation on the failure mechanism of slope deformations induced by water level fluctuation with InSAR and numerical simulation: a case study

The Alagou Reservoir was officially closed for water storage in November 2014. Since September 2016, gradual slope collapse and deformation have been observed at elevations ranging from 600 to1050 m upstream of the left bank of the Alagou Reservoir dam site. The increasing annual deformation raises significant concerns about a potential landslide, which could lead to surge waves, posing a threat to both the dam and the surrounding environment. Due to difficult access and worsening conditions, thorough exploration of the site was challenging. Consequently, After emptying the reservoir, we conducted on-site investigations using satellite D-InSAR analysis, numerical modeling, and post-event monitoring. This multidisciplinary approach aimed to investigate the relationship between deformation behavior, triggering conditions, and reservoir water level changes. Our study provides valuable insights into the complex geological processes involved in slope deformation and failure mechanisms induced by water level fluctuations. We elucidated the interplay between deformation behavior and triggering conditions, which is essential for designing effective reinforcement treatments for deformed slopes. While InSAR has proven to be a cost-effective tool for monitoring surface deformation, it offers limited insights alone. Therefore, we recommend a multi-technique approach incorporating geophysical, geotechnical, and remote sensing data for a comprehensive understanding of slope stability.

Multi-Step Ahead Water Level Forecasting Using Deep Neural Networks

Stream gauge height (water level) is a significant indicator for forecasting future floods. Flooding occurs when the water level exceeds the flood stage. Predicting imminent floods can save lives, protect infrastructure, and improve road traffic management and transportation. Deep neural networks have been increasingly used in this domain due to their predictive capabilities in capturing complex features and interdependencies. This study employs four distinct models—Multi-Layer Perceptron (MLP), Long Short-Term Memory (LSTM), transformer, and LSTNet—with MLP serving as the baseline model to forecast water levels. The models are trained using data from 20 distinct river gages across the state of Missouri to ensure consistent performance. Random search optimization is employed for hyperparameter tuning. The prediction intervals are set at 4, 6, 8, and 10 (each interval equivalent to 30 min) to ensure that performance results are robust and not due to random weight initialization or suboptimal hyperparameters and are consistent throughout different prediction intervals. The findings of this study indicate that the LSTNet model leads to a better performance than the other models, with a median RMSE of 0.00724, 0.00959, 0.01204, and 0.01230 for the 4, 6, 8, and 10 intervals, respectively. As climate change leads to localized storms driven by atmospheric shifts, water level fluctuations are becoming increasingly extreme, further exacerbating data drift in real-world datasets. The LSTNet model demonstrates superior performance in terms of RMSE, MAE, and the correlation coefficient across all prediction intervals when forecasting water levels under data drift conditions.

MOBILE APPLICATION FOR MONITORING THE GROWTH OF DONATED KIRAY TREES ON THE CISADANE RIVERBANK

The riverbank of the Cisadane in South Tangerang, Indonesia, is experiencing erosion issues due to significant fluctuations in water levels and currents. Planting trees with deep and dense root, such as Kiray trees, on the riverbank slopes can help slow down the erosion. Many institutions/individuals have planted trees in the area; however, the survival rate of the tree saplings is rarely monitored. The monitoring of 50 Kiray trees planted by Binus University in June 2024 shows that only 50% of the saplings survive after 2 months. In order to improve the survival rate, it is necessary to monitor the growth of the trees in more detail. This study proposed to develop a mobile application that can be used by many people to register and monitor the growth of the planted trees. The mobile application have been designed based-on the discussion with the riverbank community, to allow multiple users to register and update the data of the trees, including their height and location from time to time.

Failure and reinforcement of reservoir landslides: Insights from centrifuge modeling and numerical modeling

The construction of the Three Gorges Reservoir dam in China has led to an increase in reservoir landslide events. To mitigate these geohazards, multiple rows of stabilizing piles (MRSP) have been employed to stabilize massive reservoir landslides. This study utilizes centrifuge and numerical modeling to investigate the behavior of unreinforced landslides and MRSP-reinforced landslides in reservoir areas. The failure mechanisms of unreinforced landslides, as well as the mechanical behavior and stabilizing mechanisms of MRSP under reservoir water level (RWL) fluctuations, are examined. The results indicate that elevated downward seepage forces contribute to pre-failure sliding, but are not the sole cause of catastrophic failure. Instead, rapid pre-failure sliding leads to soil particle compression and crushing in the saturated sliding zone, resulting in excess pore water pressure and accelerated overall failure. This excess pore water pressure-dependent mechanism explains the observed “step-like” deformation pattern and rapid failure pattern in reservoir landslides. Furthermore, the study reveals the formation of soil arches between adjacent MRSP groups, causing stress concentration on boundary columns and necessitating reinforcement. The finding challenges traditional one-dimensional load transfer ratios, advocating for a two-dimensional approach that accounts for variations across rows and columns. Notably, the study also highlights significant variations in load transfer laws within MRSP under different RWL operations, emphasizing the need for a more nuanced understanding of MRSP behavior.

Dynamic response characteristics of molten salt solar power tower plant under rapid load changes

Utilizing molten salt STP plants in grid peak-shaving endeavors is poised to become increasingly pivotal in the forthcoming energy landscape. Investigating the dynamic response characteristics of molten salt STP systems during rapid load fluctuation is paramount for their efficient integration into the grid. In this study, a dynamic simulation model employing a lumped parameters method is present, alongside the proposition of two distinct control strategies tailored to regulate water level and load fluctuation. Moreover, to assess the resilience of STP systems to actual disturbances, three comprehensive closed-loop disturbance scenarios encompassing variations in molten salt temperature, feed water temperature, and main steam valve opening degree are conducted. Subsequently, a three-element water level control strategy is implemented to mitigate feedwater pressure and false-water level effects, and the power generation of the unit is controlled by adjusting the molten salt flow rate. Furthermore, the dynamic response characteristics of STP units during load reduction phases under varying ramp rates (3%, 6%, and 10% Pe/min) employing the two aforementioned control strategies are scrutinized, the delay effects of heat transfer and phase change processes are analyzed, and the adjustment process can be completed within 120 to 280 s, with a maximum water level overshoot of 2.5 mm. The results underscore the efficacy of the combined three-element water level control and load control strategy in ensuring safe and flexible operation during load regulation processes. Additionally, the main factors affecting the change in drum water level and the intricate coupling relationships among critical parameters are analyzed. Ultimately, these findings furnish essential guidelines for optimizing control strategy design and enhancing the flexibility of molten salt STP systems in the context of grid integration and peak load management.

Nonlinear Tide‐River‐Surge Interactions and Their Impacts on Compound Flooding During Typhoon Hato in the Pearl River Delta

AbstractIn coastal areas, multiple hydrodynamic processes co‐occur, including the astronomical tide, river discharge, and storm surge. Their propagation and interaction within coastal tidal river result in strong nonlinear behavior in inland areas. This study employed a hydrodynamic model and continuous wavelet transform analysis to investigate the complex tide‐river‐surge interactions and their impacts on compound flooding in the West River of the Pearl River Delta during an extreme typhoon event. Validated model outputs provided insights into the spatial and temporal variations of river discharge, water levels, and currents. Wavelet analysis revealed river discharge modulates tidal properties, causing nonstationary tides and asymmetries, with high flows suppressing tidal ranges but facilitating energy transfers to overtides. During Typhoon Hato, storm surges dominated high‐frequency water level fluctuations that rapidly propagated upstream. Crucially, strong high‐frequency tide‐river‐surge coupling induced significant water level amplifications, with interaction intensities increasing landward. In upstream areas where riverine and coastal drivers converged, flood risks exceeded typical estimates due to this vigorous multi‐driver compounding. Findings highlighted how existing flood mitigation approaches over simplistically superposing individual sources may severely underestimate flood levels by neglecting such nonlinear interactions. A comprehensive accounting of the cumulative, multiplicative effects of tides, discharge, storm surge, and sea level rise is imperative. This quantitative unraveling of key physical drivers offers transferable insights applicable to compound flood risk evaluations and policy guidance for enhancing resilience in other estuary and delta regions. Future work should focus on holistically modeling multivariate extremes and their interactions.

Optimizing urban flood management: enhancing urban drainage system efficiency under extreme rainfall events

ABSTRACT Extreme rainfall events, particularly those induced by tropical cyclones, pose a heightened risk to the urban drainage system (UDS). Existing UDSs, having been established long ago, often fail to account for the extreme rainfall caused by cyclones. To address this issue, this study designs a multi-objective intelligent scheduling model within a simulation -optimization framework, aiming to optimize the operation of urban drainage infrastructure and hydraulic structures. This is achieved by integrating the Storm Water Management Model (SWMM) with the multi-objective particle swarm optimization algorithm (MOPSO) and distinctly evaluating typhoons and torrential rains for their impact on extreme rainfall. The study results show that the multi-objective intelligent scheduling model can effectively devise operation strategies for pumping stations and weirs in the study area, thereby optimizing their use for urban drainage. The model was successful in reducing the total flood volume (TFV) and the water level fluctuation (WLF) by 3.11%–57.77% and 26.32%–65.48%, respectively. This not only mitigates urban flooding but also enhances the infrastructure stability of the UDS. The model outperformed the local adaptation strategy in most scenarios for the two selected objectives, suggesting that the efficiency can be significantly improved by optimizing UDSs without expansion of existing infrastructure or additional costs.