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• Flume experiments were conducted to assess the impact of submerged flexible vegetation on regular wave attenuation and beach morphology. • The presence of vegetation prevented further erosion of the beach, resulting in a reduction of 7% to 63% in experiments. • The attenuation caused by vegetation results in the wave breaking point being closer to the shoreline on vegetated sand, leading to shoreline retreat. • A dimensionless equation was developed to characterize the behaviour of the cross-shore beach profile under the protection of flexible vegetation. Coastal protection methods are evolving from hard engineering techniques to natural enhancement approaches. Aquatic vegetation provides an environmentally friendly solution by effectively dissipating waves and resisting erosion. Laboratory flume experiments were conducted to investigate the effect of submerged flexible vegetation on the regular wave attenuation and cross-shore profiles on the artificial plane beach under varying hydraulic conditions. Variations in the waveform, wave spectrum, and wave height were analysed in the vegetation zone. Results show vegetation distorts the waveform and accelerates the attenuation process of the wave energy, and wave height evolution behaves differently from the theoretically obtained attenuation by Mendez and Losada (2004) due to the underestimating vegetation-induced attenuation and neglecting sediment-induced attenuation. Additionally, the formation process of the winter and summer profiles of the vegetated beach was analysed by the screenshots. Regenerated wave breaking becomes more apparent with increasing wave periods. The critical surf similarity parameter of the vegetated beaches was found to be lower than that of a smooth, impermeable slope because of the energy dissipation. Vegetation did not alter the type of the beach profiles, as compared to the final profiles and their characteristic parameters of the unvegetated beaches. Instead, it reduced the erosion depth and brought the eroded area closer to the shoreline. Dimensionless parameters were formulated to characterize the response of the cross-shore beach profile under the shelter of flexible vegetation, and an empirical equation about maximum erosion depth was developed within the scope of the experiment. [ABSTRACT FROM AUTHOR]

• Hydrological and erosive response at event scale for a recently burned catchment. • Comparison of two hydrological models, OpenLISEM and MOHID Land. • Parametrization based on variation in boundary conditions characterizing each event. • Models performance revealed the importance of subsurface flow at event scale. • Ash and sediment movement during large event needs different model parameterization. Wildfires are a source of instability for the natural water cycle in forested watersheds, endangering the water quantity and quality reaching downstream water bodies. The faster hydrological response of a burned area leads to increased runoff and transport of sediment and ash particles during and after rainfall events. Therefore, the use of an adequate spatiotemporal resolution in hydrological models is necessary to properly estimate post-fire impacts. Especially when addressing hydrological events such as flash floods and debris flows, which are highly unpredictable and are characterized by short duration and high impact outside the burned area. This study aims to compare the ability of two hydrological models to simulate the hydrological response and sediment transport during the first year after a fire to ultimately understand which one would best serve as a post-fire hydrological predicting tool at event scale. To achieve this goal, OpenLISEM, an event-based hydrological model, and MOHID Land, a continuous model with variable timestep, were compared. Driven by several limitations identified in previous modeling exercises at this scale during the calibration phase, this work performed a parametrization through the variation in boundary conditions characterizing each event. OpenLISEM and MOHID Land models exhibited similar capabilities in simulating runoff during the first post-fire year. However, the larger erosion input parameters required by MOHID Land increase the complexity of erosion prediction and increase equifinality. In addition, MOHID Land limited capacity to perform sensitivity and uncertainty analyses emerged as a major disadvantage, hindering the assessment of the reliability of the model's predictions. Despite its limitations for not integrating subsurface flow and base flow, OpenLISEM is the most suitable model for assessing post-fire impacts on runoff and sediment production at the event scale, because of its ease of implementation and its reduced computational requirements. [ABSTRACT FROM AUTHOR]

[Display omitted] • Distribution of vegetation avoided erosion in China increased by 12.89% in 1990–2020. • Greening of the surface has significantly prevented soil and water loss. • Spatial distribution roughly conforms to the division of the Hu Huanyong line. • Surface greening promotes a increase in vegetation avoided erosion efficiency. Global surface greening is very important to slow down regional warming, promote ecological balance and sustainable development, and China has made a significant contribution to this in the past 30 years, and effectively alleviated environmental problems such as land degradation, water shortage and air pollution by rapidly increasing vegetation coverage. Previous studies have shown that vegetation plays a positive role in alleviating soil erosion, but there is no quantitative description of runoff erosion and sediment transport under vegetation evolution with long time series and high resolution in China area. In this study, we use the RUSLE model and multi-source satellite remote sensing data to simulate overland soil erosion in China from 1990 to 2020 and analyze both the temporal and spatial variation of vegetation avoided erosion (VAE) and its correlation with multiple driving factors, such as Gross Primary Production (GPP). The results show that: 1)The distribution has increased by 12.89 % from 1990 to 2020, which is significant, and indicates that greening of the surface has significantly prevented soil and water loss;2)The spatial correlation strength of VAE-GPP in China is roughly in line with the division of the Hu Huanyong line (Hu-line), which is the result of the combined effect of vegetation distribution and human activities;3)The efficiency of VAE was significantly improved, especially the forest, accounting for about 76.50 % of the total, which was twice the sum of the other types. The research conclusion is of great significance to soil erosion prevention and control, soil ecological improvement, vegetation dynamic planning and regional sustainable development. [ABSTRACT FROM AUTHOR]

• Human interventions affect the dynamics of meandering channels. • Unusual inner bank erosion and outer bank deposition occurred due to upstream damming. • Altered flow-sediment regimes and channel boundary drive the unusual meander dynamics. Human activities, such as reservoir construction and bank revetment, significantly alter downstream flow and sediment regimes and river channel changes, impacting river ecosystem services. However, our understanding of how intense human activities affect morphodynamics of meandering channels in big river systems remains incomplete due to the lack of high-resolution in-situ data. Here, we use comprehensive data encompassing hydrology and sediment, historical channel maps, and high-resolution river bathymetry to investigate the evolution of meandering bends in the Middle Yangtze River (MYR) across three distinct phases: the natural period (1490–1975), the bank revetment period (1975–2002), and the post-dam period (2003–2018). The study revealed that, in the absence of human intervention, the meandering channels of the MYR naturally experienced inner bank deposition and outer bank erosion, largely governed by curvature-induced secondary flow patterns in flow and sediment transport mode. In 1975–2002, outer-bank revetments reduced erodibility, stabilizing outer banks, while inner banks continued to experience lateral and vertical deposition, causing a narrower and deeper channel hydraulic geometry. Conversely, meandering bends had exhibited an unusual pattern of 'outer bank deposition and inner bank erosion' in 2003–2018. Channel morphological changes characterized by channel incision and widening were driven by changes from erodible bank boundaries to solidified bank boundaries, substantial reduction in suspended sediment concentration, and an altered and extended effective flow range (10,000–25,000 m3/s). Our findings highlight that human interventions such as damming and bank revetments can alter the conventional erosion–deposition morphodynamics of meandering bends in large river systems, carrying vital implications for sustainable river management in the Anthropocene. [ABSTRACT FROM AUTHOR]

• A new 2D meshless bedload sediment transport model is developed based on ESPH. • A formulation for calculating the time step size for an HLLC Riemann solver in a weakly coupled approach is proposed. • The simulated results based on the developed 2D ESPH-SW-BST model show good agreement with the measured results. • A particle configuration of eight interacting particles can yield more accurate predictions of erosion peaks in cases with significant lateral flow effects. A 2D Eulerian meshless bedload sediment transport model is developed using smoothed particle hydrodynamics (SPH) to simulate rapidly varied flows over mobile beds. In the developed model, we adopt a weakly coupled numerical approach to explicitly solve the governing equations, including 2D shallow water equations for fluid flow motion and the Exner equation for bed sediment movement at the same time step. A defined virtual bedload velocity in a weakly coupled approach is involved in the calculation of time step sizes. However, nonphysical virtual bedload velocities, which often occur in cases with nearly flat beds, require extremely small time step sizes. A formulation of the lower and upper bounds of information propagation speeds for an HLLC approximate Riemann solver is thus proposed to remedy the problem. Four case studies involving dam break flows in prismatic and erodible channels, knickpoint migration, dam erosion due to overtopping flow and dam-break flow in an erodible channel with an abrupt expansion are adopted to validate the developed model. In addition, to compare the performances of different particle interaction configurations under Cartesian uniform particle arrangements, four and eight interacting particles are obtained by changing the smoothing length. Against the measured results, the case of eight interacting particles shows more accurate predictions of erosion peaks along the measured cross-sections because the lateral flows are significant. The good agreement between the simulated and measured results shows that the developed 2D Eulerian SPH bedload sediment transport model with eight interacting particles is well suited for simulating complicated flow-induced bed erosion. [ABSTRACT FROM AUTHOR]

• A strong signal of reduced winter conditions i.e. duration, snow accumulation and frost days. • Hydroclimatic regime shift alters the sediment flux seasonality in near future. • Thaw-seasons have important role controlling the annual sediment flux. Climate change alters high latitude hydrological cycle by diminishing the snow accumulation and spring flood magnitude, and by altering temperature and rainfall finally leading to hydroclimatic regime shift from snow-dominated to rain-dominated. These changes in temperature, precipitation patterns, and discharge strongly influence geomorphological processes in fluvial environments, leading to alterations in sediment transport, erosion, accumulation, and landscape changes. We conducted comprehensive analysis of hydroclimatic trends and shifts on boreal Oulanka River system, spanning over the past five decades. A strong signal of warming temperatures (+0.61 Celsius/decade), reduced winter conditions and warmer summers (+0.41 Celsius/decade) was detected. The spring flood magnitude diminished 7 %, but high discharge peaks (Q > annual p90m3/s) during other seasons increased 22 % together with 28 % increase of annual minimum discharge. Simultaneously, precipitation intensity increased during summer. The meander migration rate (mean 0.89 or 2.55 m/year) and bank erosion volume were interconnected to ground frost, high snow sum, high discharge, and high-water level during spring flood, but no significant long-term trends were observed. Our findings underscore that climate is the first-order control on fluvial geomorphology and emphasizes the complex interplay between various hydrological and climatic factors that shape the dynamics of river systems. Based on the results, we expect to see changes in the spatial–temporal distribution of high latitude rivers sediment flux in future. In addition, more attention should be addressed to the thaw seasons controlling the sediment transport, as majority of the observed shifts took place in these months. [ABSTRACT FROM AUTHOR]