Search Results (44)

Riparian vegetation plays an important role in the morphological evolution of rivers; here, an alternative numerical methodology for modeling river morphodynamics influenced by vegetation is presented. The approach integrates a vegetation growth and flow-resistance submodule coupled with the TELEMAC–MASCARET system. Vegetation is represented at the patch scale, and its hydraulic effect is incorporated through an additional drag force in the momentum equation, while stem obstruction is accounted for using the porosity formulation in TELEMAC-2D. Vegetation dynamics consider water depth variability, interspecific competition, and nutrient availability. The model is applied to a braided river reach in southeastern Mexico. The results indicate that riparian vegetation promotes more organized flow paths, enhances bar development, and plays a significant role in modulating bar stability. These findings highlight the importance of explicitly representing flow–sediment–vegetation feedback in river hydro-morphological modeling. Full article

Rapid urbanization and increasingly frequent extreme rainfall events have intensified stormwater challenges, underscoring the need for watershed-scale strategies that integrate blue-green infrastructure (BGI). This study evaluates the stormwater control performance of combined initial reservoir storage level regulation, river water level adjustment, and green infrastructure (GI) implementation in the 42.4 km² Baihuayong watershed of Guangzhou, China. A coupled stormwater model (SWMM) was developed, calibrated, and coupled with TELEMAC-2D to simulate schemes varying initial reservoir storage levels (30.6 m to 27.6 m), river water levels (11 m to 8 m), and GI proportions (0–45%) under 2- to 100-year rainfall events. Results show that lowering initial reservoir storage levels from 30.6 m to 27.6 m enhanced runoff reduction by ~40% and reduced discharged water volume by ~30%, though overflow mitigation remained limited. Decreasing river water levels from 11 m to 8 m reduced flooded areas by up to 8.3%, with diminishing benefits below 9 m. Increasing GI coverage from 0% to 45% reduced overflow nodes from 236 to 192 and flood extent from 10.76 ha to 9.20 ha under moderate storms, but improvements were modest during extreme events. A synergistic configuration, combining a low initial reservoir storage level (27.6 m), low river water level (8 m), and a high GI proportion (35–45%), yielded the most comprehensive improvements. These findings demonstrate the strong potential of integrated BGI for watershed-scale flood resilience and provide quantitative guidance for sponge city planning. Full article

The escalating sea-level rise associated with global climate change increasingly threatens estuary regions with salinity intrusion, particularly in complex river network systems where both ecological integrity and socio-economic development are at risk. While tracer techniques are commonly employed in salinity intrusion research, numerical models capable of quantifying multi-source contributions and tracing intrusion pathways in such complex settings remain underdeveloped. This study introduces a multi-source tracer-aided modeling approach to analyze and mitigate salinity intrusion, enabling quantification of the relative contributions of various salinity sources at targeted locations. Using the Telemac-2D hydrodynamic model, we simulated salinity intrusion in the Xinbu Island estuary, Hainan Province, China. A multi-source particle tracer method was implemented to delineate intrusion pathways, leading to the formulation of targeted control strategies based on simulation outcomes. Results demonstrate that measures informed by source proportion and intrusion path analysis are highly effective: under discharge conditions of 181 m³/s and 296 m³/s, salinity levels in the northern river network were significantly reduced. This study provides a valuable framework for addressing similar salinity challenges in vulnerable estuarine environments worldwide. Full article

Sustainable management of aquatic ecosystems requires effective strategies to monitor and mitigate microplastic pollution, particularly in vulnerable tidal river systems. Microplastic accumulation in these environments poses significant environmental risks, threatening biodiversity, ecosystem health, and long-term water quality. This study employs a three-dimensional hydrodynamic model (TELEMAC-3D—v8p5) coupled with a Lagrangian particle tracking model (CaMPSim-3D—v1.2.1) to simulate microplastic transport dynamics in the lower Fraser River, British Columbia, Canada. The model incorporates tidal forcing, riverine hydrodynamics, and mixing processes, and was validated with good agreement against observed water levels. This model provides a high-resolution representation of microplastic dispersion under varying release scenarios, including emissions from combined sewer overflows (CSOs) and wastewater treatment plants (WWTPs). A novel approach is proposed to identify microplastic accumulation zones using the OPTICS (Ordering Points to Identify the Clustering Structure) clustering algorithm. Accumulation zone locations remain spatially consistent despite variations in release volume. Persistent clusters occurred near channel constrictions and shoreline segments associated with flow deceleration. These findings demonstrate the robustness of the method and provide a systematic framework for prioritizing high-risk areas, supporting targeted monitoring and informing sustainable estuarine management. Full article

Nokoué Lake is located in the south of Benin and is fed by the Ouémé and Sô Rivers. Its hydrosedimentary dynamics were modelled using Telemac2D, incorporating the main environmental factors of this complex ecosystem. The simulations accounted for flow rates and suspended solids concentrations during periods of high and low water. The main factors controlling sediment transport were identified. The model was validated using field measurements of water levels and suspended solids. The results show that the north–south current velocity ranges from 0.5 to 1 m/s during periods of high water and 0.1 to 0.5 m/s during low-water periods. Residual currents are influenced by rainfall, river discharge, and tides. Complex circulation patterns are caused by increased river flow during high water, while tides dominate during low water and transitional periods. The northern, western, and south-eastern parts of the lake have weak residual currents and are, therefore, deposition zones for fine sediments. The estimated average annual suspended solids load for 2022–2023 is 17 Mt. The model performance shows a strong agreement between the observed and simulated values: R² = 0.91 and NSE = 0.93 for water levels and R² = 0.86 and NSE = 0.78 for sediment transport. Full article

Estuaries are dynamic ecosystems with crucial environmental, economic, and social functions, driving extensive hydro-morphological research supported by numerical modeling. This study systematically reviews estuarine modeling applications over the past 15 years to identify commonly used tools, model configurations, and validation strategies, to examine regional trends in the application, and to explore and discuss the relative emphasis on hydrodynamic, sediment transport, and morphological modeling within the selected studies. Following the PRISMA 2020 methodology, a comprehensive search in Scopus and Web of Science identified 3926 articles, from which 197 met the eligibility criteria. Each study was analyzed to assess modeling software, mesh types, dimensional configurations, and validation parameters. Results indicate that DELFT3D is the most widely used tool, followed by TELEMAC and FVCOM, with a preference for two-dimensional models and structured meshes. Model accuracy, assessed through Skill Scores, confirms their reliability in representing estuarine dynamics. Additionally, findings reveal significant geographical disparities, with China leading research efforts, while Latin America and Africa remain underrepresented. This gap highlights the need to expand modeling efforts in these regions to enhance estuarine management and resilience. Strengthening numerical modeling in diverse contexts will improve the predictive capacity of hydro-morphological processes, supporting sustainable decision-making in estuarine environments. Full article

Observed longitudinal water-surface profiles are commonly used to calibrate river hydrodynamic models, relying on assumptions of lateral uniformity in water surface elevation and velocity distribution. While suitable for 1D models, this approach has limitations in regard to 2D model calibration. When 2D flow measurements are available, a more robust quantitative evaluation is necessary to assess model accuracy. This study introduces a novel methodology to improve 2D model calibration and evaluate performance. High-resolution bathymetric and hydrodynamic data collected with a multibeam echosounder (MBES) and acoustic Doppler current profiler (ADCP) were aligned to compare observed and simulated flow velocities at matching spatial locations. Statistical metrics, including relative mean absolute error and root-mean-square error, were employed to assess hydrodynamic modeling. The methodology was tested using MBES and ADCP measurements alongside TELEMAC-2D simulations of a dynamic neck cutoff on the White River, Arkansas, USA. This approach provides a 2D calibration process, enhancing model accuracy and informing parameter selection, such as channel boundary roughness and downstream boundary water surface elevation. Full article

Establishing appropriate boundary conditions is essential for developing high-accuracy hydrodynamic models. However, this task is particularly challenging in topographically varying urban domains without monotonous slopes due to insufficient boundary information. This study investigates five different boundary conditions and establishes modeling practices of boundary conditions in pluvial urban flood modeling. A numerical test model within the city of Berlin is used, employing the 2D hydrodynamic finite element module of the open-source TELEMAC system. It performs unsteady simulations with nodal rainfall inputs for various precipitation scenarios, excluding infiltration. The results demonstrate that the suitability of boundary conditions is critically dependent on the surrounding topography. For boundary segments with a positive slope, a stage–discharge curve is found to outperform the other boundary conditions investigated in this study. Conversely, for segments with a negative slope, a closed wall boundary condition appears clearly preferable. Additionally, a drainage reservoir boundary condition performs effectively for more complex boundary segments but necessitates extensive preprocessing. Based on these insights, simulations were repeated with segment-tailored boundary conditions. The results indicate that this combined model outperforms the global application of each individual model. Full article

In this study, a swash-zone model, using Larson and Wamsley formula (LW07), was combined into the Telemac-2D model system to examine the performance of modeling swash-zone processes through comparisons with field observation data. The experimental site was the Haeundae Beach in South Korea where Typhoon Phanfone occurred in October 2014, and bathymetric surveys were performed before and after the typhoon. Hydrodynamic data were also measured to validate the modeled data. The performance of LW07 was tested by running the model in two modes, with and without LW07. First, the model was run to simulate the shoreline response to an imaginary coastal breakwater. The result showed a clear discrepancy between the two modes as the sediments were considerably cumulated behind the breakwater in the case with the swash-zone formula (LW07) in the wide range along the shoreline behind the breakwater, indicating that the sediments more actively and rapidly responded to the shadowing by the breakwater with LW07. The model was also run for a realistic case from August to October 2014, which included the typhoon’s period during 2–6 October. The results showed that the morphological changes at both ends of the beach in the swash zone were simulated with higher accuracy with LW07, supporting the effectiveness of LW07 in simulating the short-term morphological changes induced by the typhoon attack. In particular, the successful simulation of the sand accumulation at the end sides of the beach’s swash zone indicates that LW07 was effective in estimating not only the cross-shore transport but also longshore transport, which was likely due to the characteristics of LW07 that calculated sand transport in both directions. The enhanced modeling performance with LW07 was likely due to the adjustment of the sediment transport rate to the instantaneous changes in the local beach slope, which could successfully control the erosion/accretion process in the swash zone more realistically. Full article

The tidal currents of the Gulf of Morbihan reach up to 3.5 m/s within a narrow (200 m large) channel connecting the sea to the inner part of the gulf. In this study, a Telemac2D model validated with a large dataset of field measurements is used to assess the resources of the gulf. The results show that two sites have the potential to host up to 48 turbines (diameter of 8 m). If the entire width of the channel is occupied by turbines, significant increases in current speed are expected to occur on each side of the main channel. Simulations also show that flow changes differ between ebbing and flooding tides. During ebbing tide, the changes are limited in amplitude and remain localised within the channel. During flooding tide, the changes are more significant, especially in the vicinity of one of the two sites where the water passing through the site is flushed into a large and shallow basin. In this area, energy extraction significantly modifies the spatial distribution of the current velocities. We consider different scenarios of tidal energy extraction. The results show that flow perturbation can be significantly reduced using a lower density of turbines, that extracting tidal energy at one site slightly reduces the resource of the other, and that the deployment of two turbines (testing conditions) has a negligible effect on ambient current speeds. Full article

Due to the changing climate, flash floods have been increasing recently and are expected to further increase in the future. Flash floods caused by heavy rainfall with snowmelt contribution due to sudden rises in temperature or rain-on-snow events have become common in autumn and winter in Norway. These events have caused widespread damage, closure of roads and bridges, and landslides, leading to evacuations in the affected areas. Hence, it is important to analyze such events. In this study, the rain-on-grid technique in the TELEMAC-2D hydrodynamic model was used for runoff modelling and routing using input of snowmelt, and precipitation partitioned on snow and rain was calculated via the hydrological model HBV. The results show the importance of including snowmelt for distributed runoff generation and how the rain-on-grid technique enables extracting flow hydrographs anywhere in the catchment. It is also possible to extract the flow velocities and water depth at each time step, revealing the critical locations in the catchment in terms of flooding and shear stresses. The rain-on-grid model works particularly well for single peak events, but the results indicate the need for a time-varying curve number for multiple peak flood events or the implementation of another infiltration model. Full article

The Mekong Delta has the world’s third-largest surface area. It plays an indisputable role in the economy and livelihoods of Vietnam and Cambodia, with repercussions at regional and global scales. During recent decades, the Vietnamese part of the Mekong Delta underwent profound human interventions (construction of dykes and multi-channel networks), which modified the hydrodynamic regime, especially cycles of field submersion. In this study, we first applied a full 2D numerical hydraulic model, TELEMAC-2D, to examine the effects of the complex channel and river networks on the spatial and temporal distribution of the flow in the 40,000 km² of the Vietnamese Mekong Delta. Then, two scenarios of relative sea-level rise in 2050 and 2100 were implemented to simulate the future patterns of water fluxes in the delta. The results show that dykes and multi-channel networks would reduce the inundation area by 36% and lessen the peak water level by 15% and the discharge over the floodplains by 24%. Despite this protection, under a relative sea-level rise of 30 cm and 100 cm, the maximum flooded area could occupy about 69% and 85% of the whole delta in 2050 and 2100, respectively. Full article

The rich biodiversity in the floodplain area is influenced by both floodplain floods and groundwater (GW). To protect the ecological environment in the floodplain area, it is essential to study the interaction between floodplain floods and GW. The objective of this paper is to propose a coupling strategy between a hydrodynamic model and a GW model to provide an accurate simulation tool for quantifying the interaction between floodplain floods and GW. The case study is conducted in the floodplain area of the middle reaches of the Irtysh River in northwest China. Firstly, a two-dimensional hydrodynamic model based on TELEMAC-2D is constructed to accurately simulate floodplain floods under wetting and drying conditions. Secondly, a GW model based on MODFLOW is developed. Finally, a coupling strategy is proposed to achieve accurate and efficient integration between the hydrodynamic model and the GW model. The calibration and verification results of the model demonstrate high accuracy, with root mean squared error (RMSE) values of 0.51 m and 0.77 m between observed and calculated GW levels for the hydrodynamic–GW coupled model. The water balance results indicate that floodplain floods serve as the largest GW recharge source in the study area, while phreatic evaporation is the primary GW discharge item. This paper represents a novel attempt to couple a two-dimensional hydrodynamic model with a GW model. The research results provide a scientific tool for the ecological restoration of floodplain areas considering both surface water and GW, as well as the comprehensive management and regulation of wetland water resources and the water environment. Full article

Oil spills are one of the most hazardous pollutants in marine environments with potentially devastating impacts on ecosystems, human health, and socio-economic sectors. Therefore, it is of the utmost importance to establish a prompt and efficient system for forecasting and monitoring such spills, in order to minimize their impacts. The present work focuses on the numerical simulation of the drift and spread of oil slicks in marine environments. The specific area of interest is the Azemmour estuary, located on Morocco’s Atlantic Coast. According to the environmental sensitivity index (ESI), given its geographical location at the intersection of the World’s Shipping Lines of oil transport, this area, as with many other sites in Morocco, has been classified as a high-risk area for oil spill accidents. By taking into account a range of factors, including the ocean currents, the weather conditions, and the oil properties, detailed numerical simulations were conducted, using the hydrodynamic TELEMAC-2D model, to predict the behavior and spread of an oil spill event in the aforementioned coastal region. The simulation results help to understand the spatial–temporal evolution of the spilled oil, the effect of wind on the spreading process, as well as the coastal areas that are most likely to be affected in the event of an oil spill accident. The simulations were performed with and without wind effects. The results showed that three days after the oil spill only 31% of the spilled oil remained on the sea surface. The wind was found to be the main factor responsible for oil drifting offshore. The results indicated that rapid action is needed to address the oil spill before it causes significant environmental damage and makes the oil cleanup process more challenging and expensive. The results of the present study are highly valuable for the management and prevention of environmental disasters in the Azemmour estuary area. The findings can be used to assess the efficacy of various response strategies, such as containment and cleanup measures, and to develop more effective emergency response plans. Full article

Flooding is prominent in West Africa, and is expected to be exacerbated, due to global climate and land-use changes. This study assessed the impacts of future climate and land-use changes on flood hazards in the Mono river catchment area of Benin and Togo. Climate scenarios from the representative concentration pathways, RCP 4.5 and RCP 8.5, and land-use projection at the horizon of 2070 were used for runoff simulation at the Athiémé outlet, and flood mapping in the lower Mono river basin. The planned Adjarala dam was also simulated, to evaluate its potential impact. The Soil and Water Assessment Tool (SWAT) was used to investigate the impact of the projected changes on runoff, while the flood-water extent was simulated using the two-dimensional TELEMAC-2D model. TELEMAC-2D was validated with satellite observation and in a participatory way with local stakeholders. SWAT showed good performance during the calibration (KGE = 0.83) and validation (KGE = 0.68) steps. Results show an increase in the magnitude of flood extremes under future climate- and land-use-change scenarios. Events of 10-year return periods during 1987–2010 are expected to become 2-year return-period events under the climate- and land-use-change scenarios considered. The planned Adjarala dam showed potentials for extreme-peak and flood-extent reduction. However, flow-duration curves revealed that the discharge of the river during low-flow periods may also be reduced if the Adjarala dam is built. Adaptation measures as well as sustainable land-use and dam-management options should be identified, to alleviate the impacts of the projected changes. Full article