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• The runoff, sediment load and runoff erosion power decreased significantly. • Compared with runoff, runoff erosion power-sediment relationship is better. • The power function of runoff erosion power and sediment is better than linear. • Erosion in particular geographic locations responds strongly to runoff erosion power. In recent years, the acceleration of urbanization in the Yangtze River Economic Belt (YREB) has brought about problems such as soil erosion, ecosystem degradation and decline in ecological service functions. Therefore, this paper selects the Fujiang River Basin (FRB) in Upper Yangtze River (UYR), and analyzes the relationship between runoff erosion power (REP) and sediment transport (ST) on the basis of analyzing the variation characteristics of hydrological elements. Based on SWAT model, a variety of scenarios are set up to quantitatively analyze the impact of different land use changes on runoff and ST and REP in the basin. The results indicated that: (1) The annual precipitation in FRB from 1960 to 2018 did not change significantly, while the annual runoff, annual ST and annual REP decreased significantly. Compared with runoff and runoff depth, the relationship between sediment transport modulus (STM) and REP is the best, especially the power function between them is better than the linear function. (2) The results of the evaluation indexes of the simulation results of the SWAT model based on the measured runoff and sediment data from 2008 to 2018 are pass and above, that is, the simulation results are considered reliable. (3) Under the five scenarios of conversion of sloping farmland to forest, conversion of dry land to paddy field and conversion of grassland to bushland and forest land, the runoff and ST in the basin decreased but the overall range was small. The simulation results of SWAT model show that the erosion of specific areas in the basin shows the greatest degree of weakening with the decrease of REP. [ABSTRACT FROM AUTHOR]

• Unprecedented monitoring datasets are available to support land health assessments. • Benchmarks enable objective and actionable data-informed management decisions. • Framework for establishing benchmarks and illustrated examples are presented. • Potential caveats and best practices for benchmarking approaches are described. • Future research needs identified for benchmark research and applications. Soil erosion can have a multitude of negative impacts on agroecosystems and society and there remains an urgent need for tools to support its management. Quantitative benchmarks based on holistic understanding of erosion processes, ecosystem function, and land use objectives can be used with monitoring data and models to inform assessments and make objective and actionable decisions about erosion management. However, managers currently lack a framework for establishing benchmarks. Here, we present a framework and evaluation of different approaches to establishing quantitative benchmarks for soil erosion and ecological monitoring and assessment that can inform land management decisions. We use monitoring data collected across Chihuahuan Desert ecosystems in the United States and an aeolian sediment transport model to illustrate how benchmarks can be established. Approaches include establishing benchmarks from relationships between soil erosion indicators, reference states and land potential, including state-and-transition models, and desired conditions from existing monitoring data. We discuss the benefits and caveats of the different approaches and show how combining different benchmarking approaches can help users ensure that benchmarks appropriately reflect thresholds for soil erosion and achievable management outcomes. We finish by identifying future research needs to support establishment and application of erosion benchmarks across agroecosystems and recognize the opportunity to extend the benchmarking approaches to management of other agroecosystem processes and services. [ABSTRACT FROM AUTHOR]

• The streamflow, sediment and heat flux input to the delta substantially increased. • The changes in the sediment and carbon pathways across delta is the result of thermal erosional processes. • Lena Delta is the World's hot spot in hydrological consequences of climate change. Water and sediment supply are essential to the health of deltaic ecosystems. Diverse datasets were integrated to better understand how climate change is shifting the supply of water and sediment to the largest polar distributary channel pattern – the Lena River Delta. Here the increase in warming rate from an average air temperature is from 4.1 °C for the period 1950–99 to 6.1 °C during 2000–21, which is higher than in the adjacent polar regions. Streamflow and sediment yield entering the Lena Delta have increased since 1988 by 56.3 km3 and 6.1×106 t, respectively; meanwhile, the Lena River's increases in water temperature in June, July–August and September were found to be as much as 1.1, 0.6 and 0.05 °C. These changes have a pronounced effect on sediment regimes in particular parts of the delta. Based on analyses of correlations between various hydroclimatic drivers and sediment concentration changes across particular distributaries of the Lena Delta extracted from Landsat datasets, bank degradation driven by thermal erosional processes (which are in turn related to air and soil temperature increases) is proved to be the primary factor of the sediment regime in the delta. The study also highlights that sediment load changes are sensitive to wind speed due to remobilization of bottom sediment. Sums of daily air temperature and wind speed over 3 days are correlated with sediment concentration changes in the delta. The results also indicate that carbon transport across the delta (both POC and DOC) depends on sediment transport conditions and water discharge and might increase by up to 10 %. We conclude that the Lena Delta can be recognized as the global hot spot in terms of the hydrological consequences of climate change, which is altering sediment regimes, stream hydromorphology and carbon transport. [ABSTRACT FROM AUTHOR]

[Display omitted] • Climate and human contributions to NPP were 62% and 38% in Loess Plateau. • Precipitation contributed to NPP much than temperature in 2000–2020. • The feedback of GTGP to NPP and climate was higher in second decade. • GTGP brings environmental benefits (river sediment, PM 2.5 , dust weather). Net primary productivity (NPP) has been the subject of numerous studies, but the qualitative and comparative study on NPP that considers human activities, climate change, and their interactions is still insufficient. The Grain for Green Program (GTGP) was established in the Loess Plateau since 1999, could be used as a reference study. The temporal and spatial patterns, change trend, and driving factors of vegetation NPP were analysed in Loess Plateau using data derived from GLASS NPP (the Global Land Surface Satellite Product), meteorology, atmospheric quality, hydrology and land use by correlation and improved residual trend analysis from 2000 to 2020. After GTGP implementation, the climate and human contributions to vegetation NPP were 62 % and 38 %. NPP increased at a rate of 6.3 g C m−2 a−1 from 2000 to 2020, which was higher in 2010–2020 (6.9 g C m−2 a−1) than it was in 2000–2010 (5.7 g C m−2 a−1). The same trend was followed by the contribution of climate change to NPP between 2010 and 2020 (70.6 %) and 2000–2010 (65 %). The GTGP core area was mostly where the vegetation NPP rising zone was located. From the original bare land in the desert area, 4442 km2 of vegetation grew and increased the NPP (68.7 g C m−2). Under the warm–humid climatic trend, the climate factors contributed to NPP more in grasslands (40 %) compared to woodlands (29 %) and precipitation (33 %) was more sensitive than temperature (12.7 %). Consequently, sediment transport, PM 2.5 and dusty weather decreased significantly. In conclusion, although climate change has a greater impact on vegetation, human activities have enhanced the impact faster in the first decade, which benefit and profit from the environment finally. [ABSTRACT FROM AUTHOR]

• The contribution of advection and resuspension was calculated by an instantaneous formula. • The proposed formula can reflect the hysteresis between suspended sediment and water flow movement. • The accuracy was improved by hybrid mechanism and ridge regression model. Estuarine and coastal areas are land-sea interaction zones where sediment particles can easily move, leading to water quality and aquatic ecological issues. The suspended sediment concentration (SSC) is an important indicator of the movement of suspended particles and coastal water environments monitoring. However, traditional in situ SSC observations cannot directly separated contributions of advection and sediment resuspension. In this study we aim to propose a hybrid mechanism and ridge regression model to improve the accuracy of instantaneous SSC estuarine and coastal waters. The new model is based on the application of hydrodynamic factors, functional principles and dimensional evaluation methods, which can analysis the effects of horizontal convective transport, vertical suspended upward movement on the SSC. It is compared with existing formulas (models) and mathematical model (Mike21) calculation results, using field data from single stations at the Yangtze River Estuarine. The comparison shows that the accuracy of the new SSC calculation model based on the equations in this paper is high. The Pearson correlation coefficient of the new model has increased by approximately 0.20, and the relative mean square error and the mean absolute error have decreased by approximately 0.26. In addition, the new model can explain the hysteresis of the sediment transport process and water flow change reasonably. [ABSTRACT FROM AUTHOR]

• Compared dynamics of discharge and sediment loads in four large basins. • Explored the impact of climate, and human activities on water and sediment. • Sediment transport showed significant decreasing trends with abrupt changes. • Human activities played a predominant role in reducing sediment transport (>80%). • Impacts of land cover change on sediment loads were basin-independent. Human activities and climate are two key factors affecting hydrological and soil erosion processes. Understanding their impacts on water discharge and sediment transport is very important for sustainable development of watersheds, particularly in subtropical regions with high precipitation and high sediment loads. We here compared the long-term dynamics of water discharge and sediment transport in four large contiguous watersheds in subtropical China and explored the importance of the main influencing factors including climate, nature endowment such as geology, and human activities. Significant differences have been observed between watersheds in terms of sediment and water discharge (p < 0.001). Pairwise comparison among the four basins demonstrated significant differences in sediment modulus among 5 of the 6 pairs (p < 0.05). The sediment modulus in the Lishui Basin was significantly higher than those in other basins, mainly due to the substantial presence of steep slopes in the mountainous region, which is prone to soil erosion. Temporally, sediment transport in the four basins was well synchronized showing significant decreasing trends with abrupt change points (p < 0.001). In contrast, no trends and abrupt change points were detected in water discharge, mainly influenced by precipitation. Human activities played a predominant role to the reduction of sediment transport (80% to 102%) compared with those of climate (-2% to 19%) across the four basins. Additionally, our study also showed land cover had various basin-independent impacts on the change of sediment transport. Through cross-basin comparisons of the long-term changes in water discharge and sediment transport, our study revealed the similarities and differences in their driving mechanisms, providing valuable information for land use planning and water resource management in large subtropical basins. [ABSTRACT FROM AUTHOR]

• We constructed a coupling model system of suitable habitats. • We simulated changes in nearshore vegetation biomass and habitat. • We considered the impact of natural and human activities on vegetation. • The growth of Zostera japonica was severely affected. Estuarine ecosystems are influenced by the combination of freshwater runoff and ocean tides, and the natural environment is intricate and complex, with special natural environmental conditions and biological habitat characteristics. The Yellow River is characterized by high sediment-bearing water flow, and the estuary forms a unique clear and turbid confluence. The Water and Sand Regulation (WSRS) from the Xiaolangdi Reservoir to the estuary and nearshore has had significant impacts on the environmental conditions of water, sediment and nutrients, further affecting the growth and development of vegetation in the nearshore zone. In recent years, more studies have focused on the effects of climate change and ocean tides on vegetation in the Yellow River Estuary; however, few studies have been conducted on the effects of the WSRS on klysmoeionion. In this study, we investigated the influence of water flow, sediment and nutrients on klysmoeionion based on long-term field monitoring and indoor control experiments; constructed a three-dimensional hydrodynamic water quality model to simulate the hydrodynamic characteristics, sediment transport patterns and nutrient salt distribution in the Yellow River Estuary under the combined influence of tides and riverine water and sediment; and further combined the growth competition model of typical vegetation (including the native species Zostera japonica and invasive species Spartina alterniflora) to construct a suitable habitat simulation model for typical vegetation communities in the Yellow River Estuary. Habitat and biomass changes in Z. japonica and S. alterniflora in the Yellow River Estuary were simulated under the influence of the WSRS and climate change. The results showed that the distribution of suitable habitats for Z. japonica and S. alterniflora in the Yellow River Estuary and offshore was characterized by a zonal distribution along both sides of the estuary, with an increasing trend of suitable habitat area from the estuary to both sides of the estuary; due to environmental conditions and inter- and intra-species competition, the biomass of Z. japonica and S. alterniflora was mainly distributed in the estuary and near the northern and southern shores, with the southern shore have the most distribution. In contrast, S. alterniflora was mainly distributed in the northern shore away from the estuary and in Laizhou Bay. During the WSRS period, the suitable habitat area of Z. japonica decreased by 25%, and the biomass decreased by 50%, while the suitable habitat and biomass of S. alterniflora were not significantly affected. The growth of Z. japonica was severely affected by the dual effects of global warming and the WSRS, while the biomass of S. alterniflora showed an increasing trend. The WSRS can further consider the growth pattern of vegetation to protect the resources of Z. japonica and to curb the expansion of the invasive S. alterniflora. [ABSTRACT FROM AUTHOR]

• Climate change effects on ice regime and water and sediment processes examined. • The ice flood reaches of the Yellow River in Inner Mongolia are taken as the case study. • Mann–Kendall test applied to define the years of temperature mutations and trends. • Meteorological condition and breakup type affect sediment transport in the channel. • Complex relationship exists among channel, hydrodynamic, sediment, and ice factors. The presence of winter ice in cold regions changes the water level, flow rate, velocity distribution, and other parameters of the river, which in turn affects the sediment concentration and channel evolution. Based on data obtained from Toudaoguai Hydrological Station from 1959 to 2021, this study examines the characteristics of the ice regime during cold and warm winters and the water and sediment transport processes along the Yellow River in Inner Mongolia in the context of climate change. The Mann–Kendall test and trend analysis were applied to define the years of temperature mutations and their trends, and the temperature mutation point was determined to be the 1987/1988 season. The study considers the effect of climate change on the combination of hydrological and hydraulic conditions. Therefore, trends in suspended sediment transport, ice type formation, water discharge, and storage in different ice flood seasons (November 1 to March 31, from 1998 to 2021) were attained. Based on the cumulative negative air temperature, winters were categorized into three types, warm, normal, and cold (52.2%, 17.4%, and 30.4%, respectively). Strong and weak grades further divide cold and warm winters, and statistical analyses were used to examine the characteristics of ice, water discharge, channel storage, and sediment transport. The duration of open water, freeze-up, ice cover, and breakup periods were calculated, and the relationship between the suspended sediment transport rate and discharge rate in these various ice periods was defined. The obtained relations show that the suspended sediment rate during the ice cover and first drift was smaller than that during the open water and post-breakup conditions. For the ice cover period, the sediment transport rate was on average approximately four times smaller than the freeze-up condition and six times smaller than the open water condition. The reduced sediment transport rate in the freeze-up period can be attributed to the weakened vertical turbulent mixing and increased flow resistance. [ABSTRACT FROM AUTHOR]

• In-situ significant wave height observations in Three Gorges Reservoir. • Temporal and spatial significant wave height variations. • Higher average significant wave height in mainstream and narrower sections. • Significant impact of water level and shipping activities. • Irregular significant wave height variations along reservoir sections. The study of wave characteristic changes is critical for understanding the role of wave erosion in the shoreline erosion of reservoirs and its subsequent impact on environmental pollution. This study utilizes RBRvirtuoso D-wave-pressure-based wave gauges to make in situ observations of the nearshore significant wave height (SWH) in the Three Gorges Reservoir. The differential and impact factors affecting the SWH under varying water levels, in the main and tributary streams, and shoreline sections are analyzed. This research also investigates the alteration of the frequency distribution of the SWH. The findings indicate that the average SWH increases as the water level increases, reaching 1.2 cm, 1.5 cm, and 1.9 cm for water levels of 150 m, 165 m, and 175 m, respectively, with a SWH frequency distribution curve that becomes increasingly smooth. The average SWH in the mainstream is 2.9 times larger than that in the tributaries, with the former having a smoother frequency distribution curve. The average SWHs in different shoreline sections are inconsistent at the same water level, with the Badong (downstream) section near the Three Gorges Dam exhibiting a significantly higher average SWH than the Zhongxian (midstream) section further from the dam. When shipping activities intensify, there is often a marked increase in the magnitude of the SWH. The SWH in narrower reservoir sections is significantly greater than that in wider sections, with average measurements of 2.2 cm and 1.4 cm, respectively. Fluctuations of the water level, shipping activities, and other factors in the Three Gorges Reservoir have a significant impact on the alteration of the nearshore SWH, and changes in the SWH from low to high water levels may result in changes in both the spatial and temporal patterns of shoreline erosion. These alterations can, in turn, affect sediment and nutrient transport, potentially exacerbating environmental pollution issues. [ABSTRACT FROM AUTHOR]

• Streamwise velocity evolution in submerged vegetated flow is predicted. • New partitioned model is proposed and applied in the submerged vegetated flow. • Flow structure and development features are illustrated in vegetated flow. The evolution of the velocity caused by submerged vegetation in river courses with regular cross sections has been poorly investigated using analytical methods. Fully understanding the longitudinal profiles of the velocity is significant and essential to study the hydrodynamic processes taking place in wetland ecosystems, which is the most important indicator of energy transfer and material exchange in fluvial ecosystems. Based on the experimental data in the literature, the streamwise velocity gradually is found to decrease in the submerged vegetation and increase in the free surface layer. A four-panel analytical model derived from exponential decay theory was developed to predict the streamwise velocity occurring both upstream and within vegetation along the main flow direction in a rectangular open channel with a submerged vegetation patch. We aim at the development of velocity, which is averaged across the vegetation and free surface layers separately, and the length scales shown in the velocity evolution. The explicit calculation expression for each parameter in the analytical model was provided, and sensitivity analysis was conducted by changing the parameters to check how the predicted velocity changed. The change in the drag coefficient of vegetation (C D) and the velocity at the leading edge of the vegetation (U 0) influenced the development of velocity. The former mainly enlarges the velocity difference between the vegetation and free surface layers after the leading edge as it increases, and the latter mainly diminishes the velocity difference before the leading edge as it increases. The error statistics is conducted and shows that the predicted and measured velocities are consistent within a relative error of 11%, indicating that the partitioned model is applicable in predicting longitudinal velocity in flows with submerged vegetation of various flexibility. The theoretical analysis of velocity development paves the way for the future studies on the flow turbulent structure and sediment transport in partially vegetated rivers. [ABSTRACT FROM AUTHOR]

• The aggregated index of sediment connectivity (AIC) was applied for the first time on large regional scale. • Both structural connectivity and functional connectivity were calculated and compared. • The role of AIC factors in the sediment patterns over the months of the year were analysed. • Correlation coefficient between monthly sediment yield data and AIC were calculated as an attempt to validate the AIC result. Hydrological and sediment dynamics have changed considerably on the Chinese Loess Plateau during the last six decades due to large scale land use changes and numerous water regulation actions. Understanding the mechanism of sediment transport change and its effects is of great importance to food and environmental security. Numerical approaches are useful to map and assess spatio-temporal patterns in sediment dynamics. This study evaluates monthly and annual sediment connectivity in the Wei River Basin (134,800 km2) at the basin and sub-basin scales using the aggregated index of sediment connectivity (AIC). For the first time, this index is applied on this relatively large regional scale. The two objectives were to (1) evaluate the performance of the AIC at the regional scale, addressing substantial differences among areas, and (2) analyze how each AIC sub-factor co-determines the monthly sediment and connectivity patterns. Results show that AIC has strong or moderate positive correlation with sediment yield from 15 out of 23 stations in the Wei and Jing sub-basin. The Jing sub-basin has the highest sediment connectivity due to degraded vegetation, while the Beiluo sub-basin has the lowest sediment connectivity on average due to better ecological restoration. Within the year, sediment connectivity is highest in April and lowest in January, due to the rainfall regime and intra-annual land cover variations. Among the AIC factors, the rainfall factor has the highest effect on sediment connectivity, implying that functional connectivity (graded by rainfall and soil cover) determines sediment dynamics more than structural connectivity (mainly determined by topography and soil permeability). This study provides one of the first large-scale estimates of spatial and temporal sediment connectivity from hillslopes to river stream and including large reservoirs, which can be further employed to implement regional ecological construction works and environmental catchment management. [ABSTRACT FROM AUTHOR]