Search Results (130)

This study introduces a novel methodology for assessing ice-jam flood hazards along river channels. It employs empirical equations that relate non-dimensional ice-jam stage to discharge, enabling the generation of an ensemble of longitudinal profiles of ice-jam backwater levels through Monte-Carlo simulations. These simulations produce non-exceedance probability profiles, which indicate the likelihood of various flood levels occurring due to ice jams. The flood levels associated with specific return periods were validated using historical gauge records. The empirical equations require input parameters such as channel width, slope, and thalweg elevation, which were obtained from bathymetric surveys. This approach is applied to assess ice-jam flood hazards by extrapolating data from a gauged reach at Fort Simpson to an ungauged reach at Jean Marie River along the Mackenzie River in Canada’s Northwest Territories. The analysis further suggests that climate change is likely to increase the severity of ice-jam flood hazards in both reaches by the end of the century. This methodology is applicable to other cold-region rivers in Canada and northern Europe, provided similar fluvial geomorphological and hydro-meteorological data are available, making it a valuable tool for ice-jam flood risk assessment in other ungauged areas. Full article

This study investigates the dynamic response mechanisms of discharge capacity in the Han River Estuary to hydrological process changes at the Yangtze–Han River confluence. By constructing a one-dimensional hydrodynamic model for the 265 km Xinglong–Hankou reach, we quantitatively decouple the synergistic effects of riverbed scouring (mean annual incision rate: 0.12 m) and Three Gorges Dam (TGD) operation through four orthogonal scenarios. Key findings reveal: (1) Riverbed incision dominates discharge variation (annual mean contribution >84%), enhancing flood conveyance efficiency with a peak flow increase of 21.3 m³/s during July–September; (2) TGD regulation exhibits spatiotemporal intermittency, contributing 25–36% during impoundment periods (September–October) by reducing Yangtze backwater effects; (3) Nonlinear interactions between drivers reconfigure flow paths—antagonism occurs at low confluence ratios (R < 0.15, e.g., Cd increases to 45 under TGD but decreases to 8 under incision), while synergy at high ratios (R > 0.25) reduces Hanchuan Station flow by 13.84 m³/s; (4) The 180–265 km confluence-proximal zone is identified as a sensitive area, where coupled drivers amplify water surface gradients to −1.41 × 10⁻³ m/km (2.3× upstream) and velocity increments to 0.0027 m/s. The proposed “Natural/Anthropogenic Dual-Stressor Framework” elucidates estuary discharge mechanisms under intensive human interference, providing critical insights for flood control and trans-basin water resource management in tide-free estuaries globally. Full article

During heavy rainfalls, overflowing sewage water flows from the Combined Sewer Overflow (CSO) chambers and pollutes the Trnávka River in Trnava, Slovakia. This paper aims to propose water retention measures for the Trnávka River as a remediation technique for CSO-affected watercourses, which can contribute to the ‘flushing’ of the riverbed. During heavy rainfalls, the Trnávka River is polluted by solid, non-soluble materials, which produce unpleasant odors and are the subject of numerous complaints by citizens, particularly during low water levels. Three inflatable rubber weirs were designed, and their design was verified using a 1D numerical model of the Trnávka River. The simulations of the proposed measures performed in the HEC-RAS 5.0 software excluded the adverse effect of the backwater on the functioning of the CSO chambers in the city of Trnava during normal flow rates and confirmed that, even after installation of the weirs, the transition of the flood wave will pass in the riverbed, not causing the flooding of the adjacent area. The chemical–physical study of the Trnávka River confirmed our assumption that higher flow rates, which can be secured by the regulation of the proposed weirs, can contribute to the purity of the watercourse in the city of Trnava. Full article

The impacts of backwater due to large dam construction on flow may lead to navigation or flood control problems in curved rivers. This study conducted flume experiments to investigate the effects of backwater on the velocity distribution characteristics of a 90-degree bend. The experimental results show that the backwater degree (η, defined as the ratio of flow depth under backwater to that under non-backwater conditions) has significant impacts on the three-dimensional velocity distribution in the bend. The depth-averaged velocities decrease with increasing backwater degree, and the deflection degrees of depth-averaged velocities are found to be highly related to the backwater degree and cross-sectional position. In this experimental setup, the mean cross-sectional velocity decreases by 67.2% as η increases from 1.00 to 3.64 for Q = 35 L/s; 63.7% as η increases from 1.00 to 3.26 for Q = 52 L/s; and 60.1% as η increases from 1.00 to 2.80 for Q = 52 L/s. The maximum values of transversal and vertical velocities near the riverbed gradually shift to the inner bank as the backwater degree increases at the 45° cross section. The center of the high transversal velocity area shifts about 0.1 m toward the inner bank as the backwater degree increases from 1.00 to 3.26 for Q = 52 L/s, which can reduce the erosion of the riverbed near the outer bank. In the current study, we also demonstrate that the growth and decay processes of secondary flow cells under backwater conditions are similar to those under non-backwater conditions. However, the scales and positions of the secondary flow cells change continuously with different backwater degrees. From the entrance to the exit of the bend, the secondary flow intensity first increases, and then decreases, with its maximum values occurring at the 45° cross section. The findings detailed in this manuscript provide insights for navigation channel design in reservoir backwater zones. Full article

Aquatic vegetation can influence hydraulic performance in channels, rivers, and floodplains. Most previous studies used cylindrical stems to simulate vegetation, while few studies used shrub-like or sedge structures that exhibited a maximum width near the top of the vegetation. In contrast, this research focuses on shrub-like structures that show a maximum width near the bottom of the vegetation. To understand the effects of aquatic vegetation on velocity distribution, water surface profile, and energy loss, experiments have been conducted in an open channel with a rectangular cross-section. The results indicated that the streamwise velocity within the lower layer remains nearly constant with depth where z/y is less than 0.20. However, once z/y exceeds 0.20, the streamwise velocity increases rapidly as the depth increases toward the water surface. Additionally, the shape of the vegetation influences the position of the inflection point. Moreover, the water level rises upstream of the vegetated area, decreases within it, and gradually returns to the normal depth downstream. The bed slope has little effect on relative energy loss, with maximum values reaching 6.61%, while the presence of vegetation leads to a significant increase, reaching up to 22.51%. The relative energy loss increases with a higher submerged ratio. A new empirical equation is proposed to estimate the relative energy loss in vegetated channels. Full article

In response to the growing demand for improved operational efficiency in road and bridge networks, constructing parallel bridges in complex river sections has become a crucial strategy. This study focuses on a parallel bridge construction project in the Jinan section of the lower Yellow River, conducting physical model tests to investigate the unique aspects of the impacts of different pier shapes and spans on the flow characteristics of sediment-laden rivers under real-world engineering scenarios. The experimental results demonstrate that the hydraulic physical model of this river section that was constructed is reliable, with a relative error of <20% in sediment deposition, in the simulation of sediment erosion and deposition, flow velocity patterns, water levels, and riverbed morphological changes during parallel bridge construction in bridge-clustered river sections. The newly constructed bridges have a limited influence on the overall regime of this river section, with their impacts on both banks remaining within controllable limits, and the river flow remains largely stable. In areas with denser pier arrangements, the phenomenon of backwater upstream of the bridges is more pronounced, and under characteristic flood conditions, the newly built bridges amplify the water level differences between the upstream and downstream sections near the bridge sites. The ranges of influence of the water level drop downstream of the bridges increase, particularly in the main flow areas. Flow velocities generally increase in the main channel, while significant fluctuations are observed in the floodplain areas. Flood process experiments reveal that the slope at the junction between the main channel and the floodplain becomes gentler, with noticeable scouring occurring in the main channel. After flood events, the river tends to evolve toward a U-shaped channel, posing certain safety risks to the piers located at the junction of the floodplains and the main channel. This research methodology can serve as a reference for studying flow characteristics in similar parallel bridge construction projects in river sections, and the findings hold significant implications for practical engineering. Full article

This article describes the reasons for and trends in the overgrowth of soft-water lakes in Belarus. Due to their unique water properties (low mineralization, pH, and nitrogen and phosphorus concentrations) and high water transparency, soft-water lakes are home to protected plant species like Lobelia dortmanna L., Isöetes lacustris L., and Littorella uniflora L. The purpose of this study was to analyze changes in aquatic vegetation distribution in seven soft-water Belarusian lakes and identify the causes of these changes. The initial data for this research were the results of field observations, the archive materials of the research laboratory of lake research conducted by the Belarusian State University for the period from 1971 to 2016, including morphometric and hydrochemical parameters, the characteristics of catchments and water exchange, and the results of studying the species composition and distribution of aquatic vegetation. The authors’ field studies were carried out in 2022–2024. We used expeditionary, hydrochemical, cartographic, and comparative research methods. The most significant changes in overgrowth were observed in Lakes Svityaz and Beloe (Luninets District). These lakes have high recreational loads. Significant negative trends were also noted in Lakes Bolshoe Ostrovito and Bredno. Over 35 years, the depth of distribution of submerged macrophytes in Lake Svityaz has decreased from 7 to 2 m, and the abundance and projective cover of semi-submerged macrophytes have increased. In Lake Beloe, I. lacustris, which forms a tier of submerged plants, has almost completely disappeared, and a previously absent strip of air-aquatic plants has formed. The total area of overgrowth in the lake has decreased from 35% of the water area to 3.2%. In Lake Bolshoe Ostrovito, Fontinalis sp., previously common at depths of up to 5 m, has practically disappeared. In Lake Bredno, the water moss Drepanocladus has spread to a depth of 4 m. In Lake Glubokoe, a new area of I. lacustris growth was discovered around an island at depths of up to 4 m. In Lake Cherbomyslo, the decrease in the species’ depth and area of distribution is associated with a weakening of the inflow of bog waters due to their backwater. The main causes of these changes are largely due to anthropogenic factors (water pollution by biogenic compounds) and, to a lesser extent, hydrological changes (decrease in the moisture content of lake catchments). Full article

Constructions located in rivers play a critical role in mitigating flood risks and supporting sustainable economic development. However, the specific impacts of bridge construction on local flood dynamics have not been thoroughly examined. This study addresses this research gap using hydrodynamic modeling with the one-dimensional MIKE11 module in MIKE Zero. A case study of the Nanyang (NY) Road Bridge in Zhejiang Province analyzed backwater effects at critical locations, including the Shili (SL) River outlet and Chengqing (CQ) Harbor. Unsteady flow simulations quantified changes in backwater height and backwater length upstream and downstream of the bridge, assessing their influence on flood conveyance capacity. The results indicate a narrowing of the river channel by approximately 4.8 m at the bridge location. Additionally, under flood conditions corresponding to 5-year, 10-year, and 20-year return periods, upstream water levels increased by 1 cm (6.53 m), 4 cm (7.15 m), and 5 cm (7.75 m), respectively. This research provides valuable insights and a scientific basis for developing flood control strategies, optimizing bridge design, and planning infrastructure projects, thereby enhancing regional flood safety and supporting sustainable economic development. Full article

IpFlux is a cost-free software developed to provide a simplified, accessible, and accurate solution for hydraulic analysis in open-channel flows. It addresses the need for tools that support rapid decision-making during early design stages, especially when conventional software may be too complex, resource-intensive, or costly. Written in Python, IpFlux features an intuitive interface and implements both explicit and implicit formulations to compute normal and critical depths, hydraulic jumps, flow through weirs and gates, backwater curves, and compound cross-sections. Thanks to its focused interface and direct data entry, IpFlux enables significantly faster estimations than traditional tools used for similar hydraulic calculations, particularly in early project stages. The software’s accuracy and applicability are demonstrated by comparing its outputs against classical references and selected results from established tools such as HEC-RAS and ANSYS Fluent. While IpFlux is not intended to replace advanced simulation software, it offers a reliable and user-friendly alternative for preliminary analyses in engineering projects, as well as for educational purposes in hydraulic engineering. Full article

Backwater effects of the Feilaixia Reservoir caused frequent inundations in the reservoir tail and complicated flood regulations in the North River basin. Currently, how backwater effects impact wedge storages and flood stages in the Feilaixia Reservoir remains unknown. This study established the 1D HEC-RAS model to simulate the water level profile and dynamic storage capacity in the Feilaixia Reservoir during two flood events and in 25 regulation scenarios. The results show that the simulated water levels aligned well with the measured data during the flood events in June 2022 and April 2024. The impact of backwater effects on flood stages, i.e., the water level difference between reservoir regulation and natural river, gradually diminished from the dam to the reservoir tail. The larger flood flow and higher water levels in front of the dam triggered greater wedge storages and higher flood stages and inundation risks in the reservoir. The narrow Mangzaixia Gorge produced a secondary backwater effect in the reservoir tail, resulting in distinct water level profile patterns above the Lianjiangkou confluence in the main stream and in the Lian River tributary. The backwater effects on wedge storage and flood stages were exceptionally large, and the ratios of wedge storages to static water storages in the Feilaixia Reservoir were 125% and 147% during both flood events, and even up to 199% as inflow reaches 20,000 m³/s, which should be carefully considered in operational flood regulation and levee height design in the reservoir. Full article

The study of river backwater points (bpts) is pivotal for understanding the interactions between riverine and coastal systems, including brackish water dynamics, coastal flooding, and ecosystem processes. Despite extensive research, the global spatio-temporal dynamics of bpts, particularly in rivers with minimal human intervention, remains underexplored. This study investigates backwater lengths and shifts in 18 major global rivers (discharge > 5000 m³/s) from 2000 to 2020, uncovering significant hydrological and geographical patterns. In 2000, backwater lengths ranged from 113.16 km (Salween) to 828.75 km (Amur), with bpts consistently positioned upstream of apex points. By 2020, all rivers exhibited upstream retreats of their bpts, ranging from 10.43 km (Salween) to 132.51 km (Amazon), and retreat ratios typically falling between 0% and 20%. The Salween, Niger (60%), and Irrawaddy (38%) demonstrated the most significant proportional shifts. Geographical transitions of bpts varied widely: rivers such as the Ganges and Amur shifted toward urbanized areas, while the Amazon and Orinoco remained in remote regions, reflecting the differential impact of human activity and natural processes. There was a general correlation between backwater length and river discharge, with exceptions like the Amur indicating the influence of other factors such as geomorphic settings and sediment dynamics. While sea-level rise (0.019–0.115 m) affected estuarine conditions, it showed no consistent relationship with bpt retreat at the global scale, but a regional-scale analysis indicates that sea-level rise can lead to the retreat of bpts for those rivers with macro-tidal environments and high sediment yields with less human intervention, suggesting localized interactions dominate backwater dynamics. These findings highlight the complex interplay of environmental and anthropogenic pressures on global river systems. They provide a critical foundation for advancing hydrological modeling, improving river management strategies, and understanding the broader implications of spatio-temporal bpt dynamics under changing climatic and human influences. Full article

Reservoir water level regulation induces intricate processes of phosphorus (P) migration and release within the water-level fluctuation zone (WLFZ). These dynamic interactions pose significant challenges for effective pollution management strategies. This study focused on two typical tributary WLFZs (narrow gorges type and wide river type) in Three Gorges Reservoir (TGR), aiming to quantify P sources and assess their release potentials across two operational periods. Results showed that the deposition of suspended particulate P (SS-P) transported from the upstream was the dominant P source in the two WLFZs during the low water level period (August 2022). During the drainage period, the main P source of the ‘narrow gorges type’ WLFZ was P loss from slope soil above the WLFZ, but the ‘wide river type’ WLFZ had a mix of P sources, including P loss from slope soil, SS-P depositions from the TGR backwater and the tributary upstream. Among the three P sources, the slope soil source exhibited a relatively higher degree of P saturation (DPS) values (0.5–18.8%), indicating a greater potential for P release. Given that P loss from slope soil is the primary P source in the WLFZs during the drainage period, which coincides with the spring plowing season, it is crucial to implement measures to prevent P loss from slope soils to safeguard water quality in the TGR. Full article

Periodic change in reservoir water level will have a significant impact on berthing position, and the impact caused by irregular operation during berthing will cause damage to wharf pile foundations. However, most of the existing monitoring methods adopt irregular methods, so it is difficult to accurately identify and analyze the damage causes. Taking a high-piled wharf in the Three Gorges Reservoir area as an example, the uncertainty of reservoir water level change is quantitatively analyzed. By establishing a simplified parametric wharf calculation model, the data set of an inversion model of pile of a high-piled wharf under ship impact is obtained, and the inversion analysis of pile damage of a high-piled wharf under ship pile is carried out based on the artificial neural network model. The results show that the inversion model can accurately and efficiently identify the intensity of ship impact, and a low water level is better than a high water level in the identification of impact position. In this paper, the behavior of wharf structure before and after damage is analyzed symmetrically under the action of damage inducement. In summary, the inversion analysis method can basically meet the requirements of inversion identification of pile foundation damage of a high-pile wharf in a backwater fluctuation area under ship impact. Full article

Flood models are essential for simulating and analysing urban flooding; however, accurately capturing the complex physical processes and their interactions remains challenging. This research introduces a multi-process flood modelling framework designed to generate realistic urban flood simulations. It integrates various hydrological and hydrodynamic processes through data-exchange synchronisation. A new surface flood control model (SFCM) was developed and applied in Huai’an District, China, using the storm water management model as its foundation. The SFCM was used to assess storm events, detect drainage outlets hindered by high river network water levels during extreme rainfall, and evaluate how river backflow affects drainage overflow and surface flooding. Results indicated that higher return periods of rainstorms reduced the number of drainage outlets obstructed by backwater, though backwater worsened surface flooding and drainage overflow. Compared to the current capacity of drainage outlets, using the maximum drainage capacity reduced the overflow rate of rainwater wells by 10.62% on average but increased river cross-section overflow by 1.72%. The average surface inundation area and maximum depth decreased by 0.78 km² and 0.05 m, respectively. This research introduces an innovative approach for simulating and analysing large-scale urban flooding, offering essential perspectives for urban planning and strategies to prevent flooding. Full article

This paper explores different methods of computing backwater depth for open-channel flow, such as one- to multi-dimensional models, finite difference approaches, and artificial intelligence methods. This paper primarily focuses on one-dimensional methods and states the implication, advantages, and disadvantages, verification process, and performance of each method. This paper discusses different parameters that influence backwater and their impact. Additionally, this paper compares the discussed one-dimensional methods with each other due to their common usage of experimental and field datasets as well as their popularity in implementation. It was concluded that while the WSPRO method significantly overestimated and the Yarnell’s method underestimated the afflux value, the measured afflux values are closest to the values computed by the energy and momentum methods. Full article