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Sediment transport has been extensively studied. There is still a need to learn more about the mechanisms that make bed particles move, which is caused by turbulent flow in the low transport stages (above the motion threshold and below continuous transport). This work is focused on the use of an advanced tool to obtain a better perception of sediment transport dynamical methods: an instrumented particle equipped with a micro-electromechanical systems (MEMS) sensor. Particle transport experiments were carried out in a laboratory flume under a variety of well-controlled above-the-threshold-of-motion flow conditions. By using sensor data, the kinetic energies were calculated with different flow rates and particle densities (mimicking different types of sediments sizes) to generate the probability distribution functions (PDFs) of particle transport features, like the total kinetic energy of particles, which provided information about particle interaction with the bed surface during its motion. The energy transfer efficiency was also studied, which can link the rate of energy transferred from the flow to the particle transport, so it can determine how efficiently a flow can transfer energy to the particle and how it affects the magnitude of sediment transport. In general, the instrumented particle response by a series of experiments showed consistent and satisfactory results and demonstrated its capability to record inertial dynamics because of flow turbulence at low cost. These experiments used different particle sizes and densities than those found in real-world sediments because of sensor size and lab limitations. They do, however, provide a framework and trends that others can use to do more research into bed load transport rates in built canals and natural rivers. [ABSTRACT FROM AUTHOR]

We studied hydrological and geomorphological transformations in the Don River Delta, South Russia, due to river engineering and climate change over century and decadal time scales and how these transformations affect integrated coastal zone management (ICZM). The most eastern and one of the largest of Mediterranean-Black Sea delta basins, the Don River Delta is under-represented in international studies. The impacts river runoff (RR), fluvial sediment delivery (FSD), waves and marine surges on changes in the migration of the delta front (DFM) were assessed. There were several major river changes beginning with the construction of the Tsimlyansk dam in 1952. FSD decreased dramatically from 1933 until the present and the Delta changed its functional state from river-dominated to wave-dominated starting in the mid 1990s. Annual maximum water height (MHA) in the center of the Delta increased in variability and amplitude from the mid-1980s and was more influenced by strong marine surges as a result of more frequent westerly winds. Climatically-induced surges interacting with waves caused increased erosion of the delta front, but brought in high levels of resuspended marine sediments. FSD was statistically positively related to DFM by the end of the 20th century. DFM was statistically positively related to MHA by the end of the 1990s. We assessed the risk of coastal flooding caused by more frequent and stronger surges over the last forty years on economic damage for the settlements in the Don Delta. We conclude that ICZM for the Don Delta is needed now because urban population growth increases exposure to more frequent coastal flooding in the Delta and recent changes of DFM negatively influence protected areas. A coastal management plan to address erosion and flooding is a first step of ICZM of the Don Delta. • Fluvial sediment delivery (FSD) to the Don Delta decreased by about 90% from 1933 due to river regulation. • Delta front migration (DFM) was positively correlated with FSD from 1953 until the end of the 1990s. • Storm surges became more frequent and stronger from the 1990s until now. • A coastal management plan is necessary for addressing erosion and flooding in the Don Delta. [ABSTRACT FROM AUTHOR]

The impacts of coastal changes and human land use on depositional processes, ecological conditions, geomorphic evolution and harbor works at the archaeological site of Lattara, one of the oldest cities of the northwestern Mediterranean built in a deltaic environment, were investigated from a multi-proxy approach based on sedimentological, biological and geochronological analyses. A distributary channel connected to the ancient harbor of Lattara was deepened and channelized around 200 cal BCE. The drastic increase in water depth caused by channelization was associated with increased flow competence and bedload transport, and could have improved navigation in the harbor area. By contrast, high accumulations of anthropogenic deposits in the channelized stream from the second century CE seem to have negatively affected sediment transport conditions by reducing bedload flux. The construction of a cobble pavement on the western bank of this channelized stream in the fourth century CE was contemporaneous with a sharp decrease in bedload transport showing an abrupt transition to a low energy environment such as in abandoned channels. A drainage ditch was then dug in the deposits of the channelized stream during the Medieval Warm Period, in a context of land use intensification and increased river flooding that led to the deposition of coarser sediments. • Reconstruction of the delta architecture in the Lez River coastal plain. • Role of land use, autogenic processes and hydroclimate changes on sediment flux. • Sea level reconstruction over the last 7000 years in the Lez delta plain. • Channelization and deepening of a distributary in the harbor area of Lattara. • Increased competence and bedload transport caused by channelization. [ABSTRACT FROM AUTHOR]

Spur dikes, vital for enhancing river ecosystem biodiversity, also contribute to the creation of intricate flow patterns and scour phenomena. In the context of existing research, which predominantly concentrates on single spur dikes, this study stands out by specifically delving into the temporal changes in scour depth near initial spur dike in multiple spur dikes. Varied spacings, lengths and flow velocities are considered in this exploration. After comprehensive literature analysis, it could be asserted that use of multiple spur dikes consistently results in shallower equilibrium scour depths compared to a single spur dike. The study introduces a predictive model by examining the impact of different influencing factors, including spacing, length, and flow velocity, on scour depth. The proposed equation establishes a robust correlation between the observed and estimated scour depth values. The study explores the temporal changes in scour depth, revealing that the time needed to arrive at equilibrium scour depth is drastically reduced when employing multiple spur dikes. Furthermore, the investigation highlights that in multiple spurs in series, the maximum equilibrium scour is lower compared to that in single spur dikes. The model, encompassing various parameters such as flow velocity, spacing, length, and time, demonstrates high predictive accuracy. Overall, this study provides valuable insights into the dynamic behaviour of scour at multiple spur dikes and offers a predictive tool for effective riverbank protection and ecosystem management. In doing so it contributes to the overarching aim of achieving Sustainable Development Goals (SDGs) in river management ecosystem preservation. • Examines scour near first spur dike in a series of three. • Higher flow intensifies equilibrium scour depth, crucial for design. • Introduces predictive model using spacing and Densimetric Froude. • Proposes empirical formula, demonstrating high accuracy in temporal scour prediction. • Highlights effective insights for scour processes in river engineering. [ABSTRACT FROM AUTHOR]

• Circuits of capital explain some transformations of rural areas since the modern era. • The socio-ecological fix provides a way to think about the many changes related to capitalism. • Circuits of capital produce palimpsest landscapes etched by generations of development. • Rural elected officials can adopt the economic development models of entrepreneurial cities. • Some marginalized rural areas become reservoir spaces for the circulation of capital. Although the circuits of capital model emphasizes the part played by the overaccumulation of capital at the core of capitalistic development, scientific research has seldom used this framework for analysing rural dynamics. After proposing a theoretical approach involving circuits of capital, rural areas and the socio-ecological fix, we draw on different historical sources, semi-directive interviews and press articles to understand how circuits of capital largely altered the socio-ecosystem of France's upper Saône valley until the mid-nineteenth century before being directed instead towards other more urban areas. The marginalizing of this rural space by the third circuit of capital tended to reduce the socio-ecological transformations expected of capitalistic development in the twentieth century. Political actors at all levels then played a decisive role in the circulation of capital and the shaping of the river and its floodplain. Inclusion in the fourth circuit of capital is an objective for some political actors today who are developing strategies for branding and marketing the local area. If it develops successfully, this fourth circuit of capital will make a sizeable impact on the urbanization of this rural area, setting it on a new trajectory in terms of transformations of the river. It seems that each generation of circuit of capital involves greater socio-ecological impacts than the previous one, forming a palimpsest of capitalistic development. [ABSTRACT FROM AUTHOR]

[Display omitted] • Loss of longitudinal connectivity on average at 72 % in the Austrian Danube system. • Barrier passability increased by fish passes between 20 % and 24 %. • Natural connectivity gradient strongly disrupted. • Measures to connect and restore habitats of potamodromous fish populations needed. In this study, we explored how barriers such as dams have affected the longitudinal connectivity of riverine habitats from the perspective of potamodromous fish. For this purpose, connectivity changes are investigated in the central part of the Austrian Danube system, where the national reporting for the EU Water Framework Directive provides detailed information on the position and characteristics of barriers as well as the distribution range of native fish species. This assessment is based on an estimation regarding the quantitative upstream and downstream passability of individual barriers, where we further investigate three different passability scenarios to account for uncertainties. We then apply several combinations of passability scenarios and assumptions on dispersal distances to calculate a series of network-based reach and catchment connectivity indices. On average, the estimation of barrier passability indicated a high downstream passability, while upstream passability was substantially lower across scenarios. Furthermore, existing fish passes were estimated to have increased passability on average between 20 % and 24 %. Overall, the results indicated a strong effect of barriers on the longitudinal connectivity of the investigated river network. Catchment scale indices revealed a loss of connectivity, which increased with dispersal distance. Reach connectivity indices displayed a strong disruption of the natural connectivity gradient along the river network and indicated that individual river reaches have, on average, become more isolated in addition to the overall decrease in connectivity. The average loss of connectivity across scenarios was estimated at 72 % (SD = 16 %) when taking into account all connections to other reaches and 66 % (SD = 7 %) when only connections to upstream reaches were considered. We conclude that longitudinal connectivity in the Austrian Danube system is still severely compromised, making it increasingly challenging for potamodromous fish species to complete their life cycle. This issue is further amplified by the severe loss of fish habitats as a consequence of river engineering. [ABSTRACT FROM AUTHOR]

River morphology is one of the most important fields of river engineering and the study of the changes in the flow direction and cross-sections of a river. Over the past years, using the unique properties of remote sensing (RS) and satellite images, many studies have been conducted on rivers' morphological changes. In this study, the morphological changes of the river boundary displacement and the changes in river width resulting from deposition and erosion during 30 years period (1985 to 2015) in the Bazoft River, one of the North sub-basins of the Karun River basin in Iran, using 26 satellite images of TM, ETM+, and OLI Landsat in the ENVI 5.3 and ArcGIS 10.3 software have been assessed. The results indicated that the greatest change in the river bank takes place in the distance between 62 and 84 km from Karun-4 Dam to the upstream. Besides, analyzing long-term periods indicated that in the time intervals of 1985–1994, 1994–2005, and 2005–2015 the sediment had deposited along river banks. For 30 years, the river's average deposition and erosion levels areas are estimated to be 69.4 and 42.4 ha, respectively, meaning that ground with 27.1 ha is formed by virtue of deposition. According to the assessments, it was indicated that there is no significant difference between average deposition and erosion on the left bank in short periods, and the deposition bank is approximately 2% greater than bank erosion. However, on the right bank, the deposition level is approximately 8% greater than erosion, which is significant at a confidence level of 95%. The results of this study perfectly indicated the ability of sub-pixels and the use of water indicators in revealing the river form changes using Satellite Images Time Series (SITS). [ABSTRACT FROM AUTHOR]

Dam removal can generate geomorphic disturbances, including channel bed and bank erosion and associated abrupt/pulsed release and downstream transfer of reservoir sediment, but the type and rate of geomorphic response often are hard to predict. The situation gets even more complex in systems which have been impacted by multiple dams and a long and complex engineering history. In previous studies one-dimensional (1-D) models were used to predict aspects of post-removal channel change. However, these models do not consider two-dimensional (2-D) effects of dam removal such as bank erosion processes and lateral migration. In the current study the impacts of multiple dams and their removal on channel evolution and sediment delivery were modeled by using a 2-D landscape evolution model (CAESAR-Lisflood) focusing on the following aspects: patterns, rates, and processes of geomorphic change and associated sediment delivery on annual to decadal timescales. The current modeling study revealed that geomorphic response to dam removal (i.e., channel evolution and associated rates of sediment delivery) in multiple dam settings is variable and complex in space and time. Complexity in geomorphic system response is related to differences in dam size, the proximity of upstream dams, related buffering effects and associated rates of upstream sediment supply, and emerging feedback processes as well as to the presence of channel stabilization measures. Modeled types and rates of geomorphic adjustment, using the 2-D landscape evolution model CAESAR-Lisflood, are similar to those reported in previous studies. Moreover, the use of a 2-D method showed some advantages compared to 1-D models, generating spatially varying patterns of erosion and deposition before and after dam removal that provide morphologies that are more readily comparable to field data as well as features like the lateral re-working of past reservoir deposits which further enables the maintenance of sediment delivery downstream. [ABSTRACT FROM AUTHOR]

Vegetation forms an integral part of ecological system in river engineering. Aquatic vegetation found in streams and rivers can be broadly classified as floating, submerged and emergent vegetation. The current study deals with analyzing the turbulence characteristics in a vegetated channel. Experiments were carried out using rigid and flexible vegetative models installed in the open channel flume. Velocity data at different measurement points were collected using Acoustic Doppler Velocimeter (ADV). A constant discharge was maintained throughout the experiment. It was observed that the presence of vegetation can significantly influence the turbulence characteristics in a channel. The Reynolds shear stress as well as the turbulence intensity was found to decrease with the vegetation. However, at the downstream sections of the vegetative models, there were significant flow fluctuations in the case of both rigid and flexible vegetations. Moreover, analysis of third-order moments revealed that vegetation attenuates the downward flow in a channel, thereby making the channel bed more stable. On the other hand, it was found that flexible vegetation can efficiently control the turbulence fluctuations as compared to rigid vegetation, hence proving to be better alternative when it comes to river protection works. Further comparison was also presented with an existing literature to get a more comprehensive idea in this field. Therefore present study provides an insight into the fact that with the help of flexible and rigid vegetation one can restore the ecological balance in the river. The riparian vegetation would be very useful for the river engineers and managers to improve the ecosystem health. • Vegetation forms an integral part of ecological system in river engineering. • Experiments were carried out using rigid and flexible vegetative models. • Reynolds shear stress, turbulence intensity and third order moments were determined for understanding the flow in channel. • A positive value third order moment indicate that the longitudinal flux of the Turbulent Kinetic Energy (TKE) is taking place in the flow direction. • Vegetation can play an important role in stabilizing the channel bed and hence restricting the transfer of bed materials, thereby reducing erosion. [ABSTRACT FROM AUTHOR]

Korean historical documents have abundant records of river works. Extensive related records during the Joseon Dynasty (CE 1392–1910) were investigated and analyzed. The evolution of man-made urban stream, Cheonggyecheon the center of old downtown Seoul, Korea was reviewed. In 1410, after a big flood, 52,800 soldiers were mobilized from whole country to improve waterway in the capital. King Sejong continued to enhance the river maintenance. The dredging and expansion for main stream including tributaries was conducted to reduce flood risk. It was a landmark river engineering project for the improvement of the capital's infrastructure. King Yeongjo planned and initiated the massive river work project. 200,000 people were recruited from five local provinces to widen the stream and to build up the stone embankments, and the waterways were straightened up to present conditions. After the project, the Juncheonsail , a construction report was published and adopted as a practical guideline for river management. As a result, floods in downtown of the capital had been somewhat controlled though, since then every King of the Joseon Dynasty had deep consideration on river maintenance including dredging and embankment against flood and sedimentation. This paper aims to introduce a brief history of the systematic urban river management in ancient Korea. [ABSTRACT FROM AUTHOR]

• Improve the one-dimensional model with the river regulation works being considered. • Compare the fluvial processes with and without the effect of river regulation works. • Investigate the impacts of river regulation works on channel evolution. In an alluvial river, various kinds of river regulation engineering are usually constructed along the reach for the stability of channel regime and the safety of flood control, which greatly affects the process of channel evolution. Therefore, a one-dimensional (1D) morphodynamic model has been improved to simulate the fluvial processes influenced by large-scale river regulation works. In the refined model, each node of a cross-section was labeled using a specified point code representing the zones of floodplain and main-channel with or without regulation engineering, and sediment transport and bed deformation in different zones were treated separately. In the zones without regulation engineering, both bed deposition and bed erosion were permitted to occur; in the zones with regulation works, bed deposition was allowed, while bed erosion was not permitted to occur owing to the restriction of those engineering, unless there was a deposition layer newly formed over the previous simulation period. Then the improved model was calibrated and verified using field observations through the application to a 347-km-long alluvial channel located in the Middle Yangtze River in China. The results for the year 2016 show that the channel scour volume without the effect of river regulation works was 9% greater than the measured value (34.43 × 106 t), while the outcome considering this effect (35.81 × 106 t) was in closer agreement with the measurements. Moreover, the variation in channel geometry obtained from the improved model agreed better with the observed data. River regulation works would limit the channel incision, and it is likely to scour the other unprotected bed of a cross-section or the downstream cross-sections as the flow cannot carry enough sediment from the protected bed. Simulated results indicate that part of the main-channel zone at the Jing65 section was protected, but the riverbed continued to incise by about 0.68 m in the protected area when the effect of bed-protection works was not considered in the model, which was not in accord with the observed channel geometry. Therefore, this effect of large-scale river regulation works on channel evolution needs to be considered for a higher simulation accuracy. [ABSTRACT FROM AUTHOR]

High resolution sediment records in the Yangtze Delta front were constructed to reveal recent environmental changes in response to river basin human activities. Increases in nutrient and organic C influxes that began in the 1950s, together with elevated primary productivity and increased chemical fertilizer application, suggested a shift toward anthropogenic-predominated environmental changes during this period. The depletion of total organic C (TOC), total N (TN), and biogenic Si (BSi), along with the decline in sedimentation rate and coarsening of sediment coincided with the development of hydrological engineering in the river basin from the 1980s. Reservoir Si retention substantially altered river mouth primary productivity community composition from diatoms to non-diatoms, thereby changing the BSi/TOC molar ratio in the sediment profile. Estimation of biogenic component burial fluxes was conducted to assess the variation and potential impacts. A recent dramatic decline in biogenic component burial in the delta area suggested a low nutrient removal efficiency in this region, due to the decrease in sediment discharge. Consequently, more nutrients have been further transported to the inner shelf and open waters instead of being buried in the delta sediment, thereby increasing the environmental pressure in the Yangtze Delta and adjoining coastal area. Image 1 • The decline in nutrient burial rate suggested low nutrient removal efficiency. • The anthropogenic-predominated environmental changes began in the 1950s. • Increasing hydrological engineering induced the depletion of nutrients since 1980s. A recent decline in nutrient burial in the Yangtze Delta was found suggesting decreasing nutrient removal efficiency and increasing environmental pressure. [ABSTRACT FROM AUTHOR]

• A new model for computing flow velocity in open channel flows with submerged vegetation is proposed. • A Darcy–Weisbach-coefficient-like parameter is proposed. • Parameters for a two-layer flow estimation approach are estimated by genetic programming. Predicting the bulk cross-sectional average flow velocity in open channels with submerged vegetation is an important topic in river engineering. Researchers have proposed numerous theoretical and empirical formulae, but the accuracy and physical basis of their solutions still need improvement. This study separates the flow into vegetation layer and surface layer, following conventional two-layer approach, and estimates the average velocities in these two layers separately. In the vegetation layer, force balance equation provides the basement of the estimation. And in the surface layer, we use genetic programming (GP), a data-driven method. A Darcy–Weisbach-coefficient-like parameter is proposed for the surface layer, which is related to other parameters through the GP algorithm. The maximum dissimilarity algorithm (a data-clustering algorithm) is used to separate the existing data sets in the training, validation, and testing groups to feed GP algorithm. Finally, by weighted combination, a new velocity formula with high accuracy and physical basis is proposed for submerged vegetated flow. [ABSTRACT FROM AUTHOR]

Abstract A decades-long, progressive loss of channel capacity in the Skokomish River, a 622 km2 basin draining the southeast Olympic Mountains of Washington State, has caused increasing flooding with severe consequences to endangered salmon runs, infrastructure, and private property. To differentiate among multiple potential drivers of the capacity loss, we analyze the geomorphic evidence for the potential effects of: flow regulation by two dams constituting the Cushman Hydroelectric Project, which began regulating flow in the river's North Fork in 1925 and diverting water out of the basin in 1930; sediment production from mid-twentieth century logging in the river's South Fork basin; and twentieth century river engineering in the mainstem. Bankfull channel capacity in the mainstem has steadily declined since about 1940 from 370 m3 s−1 to <100 m3 s−1 due partly to the narrowing of the Skokomish River, which in 2015 was only 45% as wide as it was in 1938. The capacity loss is also due to sediment filling the channel, with nearly 2 m of aggradation measured at a stream gauge since 1965. Comparison of channel cross sections surveyed in 1994, 2007, and 2016 show that about 20,000 m3 yr−1 (34,000 Mg yr−1) of sediment is accumulating in the Skokomish River. The nature, timing, and spatial pattern of this channel narrowing and shallowing are consistent with the response expected from the Cushman Project, which exports water out of basin and thus substantially reduces downstream flows, but, because the dams were built below a natural lake, does not reduce the sediment supply. While sediment yield from the South Fork is high, accounting for about three-fourths of the total sediment supplied to the Skokomish River, it is dominated by the progressive widening of the channel and recruitment by lateral fluvial erosion of glacial sediments in alluvial terraces; landslides associated with logging in the South Fork basin produced a small amount of sediment relative both to the sediment produced by channel widening in the upper South Fork and to the rate of aggradation in the mainstem Skokomish River. The naturally-high sediment load from the South Fork and the flow reduction in the North Fork result in the unusual effect of flooding having increased downstream of the dams despite substantial reductions to peak flows. This case study illustrates how a watershed-scale analysis of multiple land uses and flow management and their interaction with the basin's geology and geomorphology can make use of geomorphic evidence to differentiate among the possible drivers of channel change and associated flooding. Highlights • The Skokomish River's reduced channel capacity causes it to flood many times a year. • Flow regulation and a high downstream sediment supply caused channel capacity loss. • High sediment supply is primarily from paraglacial sources and not from land use. • Flow regulation increased downstream sedimentation, flooding, and avulsion hazards. • Geomorphologic evidence can distinguish among potential causes of channel response. [ABSTRACT FROM AUTHOR]

The aim of this research was to assess the impact of hydrotechnical works within the riverbed and riparian zone on the mobility of mercury in soil and its outflow to the river and the sea. Deepening and reconstruction of the riverbed or the cutting of reeds, influenced the fate of mercury in the river system. However, only activitis that disturbed the riperian zone increased mobilization of Hg in soils. Hg transformations in these places were controled by inflow of fresh organic matter in soil and sediments as well as by oxidation-reduction potential. In areas where reducing conditions occurred, mercury released from the soil was incorporated into the sediment. However, in areas where oxidizing conditions prevailed in the sediment, mercury flowing out of the soil occurred mainly in dissolved form and most of it was transported downstream from where it could reach the sea. Unlabelled Image • Research was conducted on three rivers before and after hydrotechnical works. • Hydrotechnical works influenced the fate of mercury in the river system. • Reconstruction of the riverbed increased the outflow of Hg from the soil. • The reeds removal did not stimulate mobilization of Hg from the soil. [ABSTRACT FROM AUTHOR]

Abstract Accurate prediction of the cross-sectional profile of stable alluvial channels is very important for hydraulic engineers in the design and construction of natural channels in urban watersheds. This paper presents the first-time application of Emotional Artificial Neural Network (EANN) modeling to predict the stable cross-sectional geometry of alluvial channel profiles. EANN applies emotional stimulus parameters to improve the network's training process. The key input parameters of the EANN model include modified Froude number (Fr m), dimensionless mean sediment size (d*) and dimensionless lateral distance from the channel centerline (x*), and the output (or target) is the dimensionless vertical boundary level of the channel cross section (y*). Several observational datasets are used with different hydraulic and geometric conditions to verify and validate the model. Feed forward neural network (FFNN) and Gene expression programming (GEP) models are also designed to make a better evaluation and comparison of EANN performance. Furthermore, the prediction accuracy of the new EANN model is compared with several popular existing relationships related to previous researchers. The results declared that the EANN model with low error values of correlation coefficient (R) equal to 0.99 and root mean square error (RMSE) equal to 0.00058 is more accurate than FFNN model (R = 0.76 and RMSE = 0.231), which represents a significant improvement in EANN performance compared to classical FFNN. It is found that the EANN model has the lowest RMSE compared to all previous models (RMSE = 0.13 for the best previous model related to Diplas, 1990). Uncertainty analysis is performed to evaluate the quantitative performance of the new EANN and existing models. The results indicate that EANN has the lowest Width of the Confidence Bounds (WCB) and the lowest Mean Error of Predictions (MEP) of ± 0.00004 and -0.00041 respectively compared to FFNN and GEP and also previous models. Therefore, the new EANN model is proposed as a superior alternative to existing models for river engineering applications in the design of stable natural alluvial channels. Highlights • A new extensions of the Emotional Artificial Neural Network (EANN) is introduced. • EANN is applied to predict the cross-sectional geometry of alluvial channel profiles. • Uncertainty analysis is applied to measure the reliability of proposed method. • The obtained results are compared with the results of popular AI methods. • The proposed method can be used as an alternative in practical applications. [ABSTRACT FROM AUTHOR]

Abstract Korean historical documents have abundant records of river works. Extensive related records during the Joseon Dynasty (CE 1392–1910) were investigated and analyzed. The evolution of man-made urban stream, Cheonggyecheon the center of old downtown Seoul, Korea was reviewed. In 1410, after a big flood, 52,800 soldiers were mobilized from whole country to improve waterway in the capital. King Sejong continued to enhance the river maintenance. The dredging and expansion for main stream including tributaries was conducted to reduce flood risk. It was a landmark river engineering project for the improvement of the capital's infrastructure. King Yeongjo planned and initiated the massive river work project. 200,000 people were recruited from five local provinces to widen the stream and to build up the stone embankments, and the waterways were straightened up to present conditions. After the project, the Juncheonsail , a construction report was published and adopted as a practical guideline for river management. As a result, floods in downtown of the capital had been somewhat controlled though, since then every King of the Joseon Dynasty had deep consideration on river maintenance including dredging and embankment against flood and sedimentation. This paper aims to introduce a brief history of the systematic urban river management in ancient Korea. [ABSTRACT FROM AUTHOR]

• This study comprehends the spatiotemporal heterogeneity in the vegetation-flow regime in a large braided river. • Study revealed that the combination of moderate and dense vegetation type has a higher rate of succession than the light vegetation cover over the decades. • A process-based indicator (stability trajectory indicator) has been developed and suggests a transitional behaviour of the river's stability trajectory. • The combined effect of non-linear hydro-geomorphic constraints primarily control the morphological activity of a large braided river. The dynamic evolution of a large braided river system is characterized by sporadic operation, impacted by a diverse range of natural and anthropogenic factors. The hydro-geomorphological interaction within the river corridor and its surrounding ecosystem presents a complex process, posing challenges in comprehending its dynamics. This study investigated the spatiotemporal heterogeneity in the vegetation-flow regime of a large braided reach of mighty Brahmaputra river. A detailed statistical analysis for the last three decades (1990 to 2019) was performed to demonstrate the in-stream vegetation characteristics for the selected middle reach (240 km) of the river. Google earth engine platform and advanced geospatial techniques have been used in this study. A novel indicator called stability trajectory indicator was developed that utilized vegetation information to identify the stability state of braided reaches. The findings of this study indicate a substantial increase in moderate and dense vegetation cover compared to light vegetation cover over the past decade. These results highlight the pronounced influence of increased moderate and dense vegetation type on the stability criteria of the reach, surpassing the contribution of light vegetation. The approach outlined in this study holds potential for river engineers to develop an effective management strategy for monitoring and maintaining river health. [ABSTRACT FROM AUTHOR]

[Display omitted] • Transport-transformation coupled model can accurately simulate nitrogen dynamics. • Nitrite reduction pathway was the rate-limiting step of nitrogen removal processes. • Hydrodynamic condition in river confluences enhanced nitrogen removal processes. • Enhanced nitrogen removal processes can sustain in downstream areas. River network comprised by varieties of interconnected rivers is an essential form of lotic environments. Unravelling the biogeochemical processes are essential for promoting the water quality and ecological health of river networks. However, biogeochemical processes in river networks are difficult to be quantified, since they are controlled by multi-directional mass transport processes and transformation processes associated with varieties of microbial metabolic pathways. To address this gap, the present research combined turbulence model and gene-centric model to establish a systematic modelling method to quantitively describe the nitrogen dynamics in a river network. The proposed model can capture the mass transport and microbial metabolic processes, and can accurately simulate the distribution characteristics of chemical materials and functional genes. The relative errors between simulated results and in-site measured data were low than 40%. With the help of the modelling method, this study further investigated the nitrogen dynamics in the river network. The results illustrated sulfide oxidation and nitrate reduction pathway and anaerobic ammonium oxidation pathway, participated by genes hzo and nap respectively, were the main pathways of NO 3 – and NO 2 – reduction. Besides, these two pathways exhibited high rates in all of the six confluence hydrodynamic zones (CHZs) of the river network and further increased the nitrogen removal efficiency. Moreover, the high-rate nitrogen removal processes continued in the downstream areas after CHZs, and the scope of such continuous influences increased with the discharge ratio between tributary and main stream. The modelling method and results in this research can be useful for prediction of water environmental quality and design of river connection engineering. [ABSTRACT FROM AUTHOR]

[Display omitted] • Multi-strategy daily suspended sediment forecasting in the Godavari river basin. • Potential of five feature selection methods coupled with empirical wavelet technique. • Application of the encoder-decoder bidirectional long short-term memory and XGBoost. • Promising performance of the E WT -E DBi -LSTM-Boruta strategy to forecast the SSL. Forecasting accurately suspended sediment load (SSL) in the basin is one of the most critical issues for river engineering, environment, and water resources management which effectively reduces flood damages. In this study, a new multi-criteria hybrid expert system comprised of empirical wavelet decomposition (EWT) integrated with Encoder-Decoder Bidirectional long short-term memory (EDBi-LSTM), supported by five feature selection (FS) methods was developed for the first time to forecast daily SSL at two study sites (Bamini and Ashti) of Godavari river basin, India. The employed FS schemes are including Boruta-Random forest (BRF), simulated annealing (SA), Relief algorithm, Ridge regression (RR), and Mutual information (MI) where the BRF coupled with EWT and EDBi-LSTM (i.e., E WT -E DBi -LSTM-Boruta) is identified as the main forecasting paradigm. Here the original SSL signals in the monsoon season (2001–2015) as the only input information were considered to forecast SSL events at a daily time scale in both study zones. The SSL signals were decomposed using the EWT technique considering the significant antecedent time-lagged inputs based on partial auto-correlation function (PACF). In the next stage, five FS strategies were addressed to specify the significant sub-sequences to reduce computational cost and enhance forecasting accuracy. Besides, the extreme gradient boosting (XGB) approach was implemented to compare the potential of the hybrid EDBi-LSTM and standalone counterpart models for both study sites. According to several goodness-of-fit indices and validation tools, the outcomes at the Bamini and Ashti sites demonstrated that the E WT -E DBi -LSTM-Boruta as the main model, achieved the best accuracy, followed by E WT -X GB -Boruta, E WT -E DBi -LSTM-SA, and E WT -X GB -SA, respectively. Comparing all the hybrid models showed that the BRF, SA, and RR strategies performed better in integration with machine learning (ML) models. [ABSTRACT FROM AUTHOR]

Highlights • A new approach is applied to estimate the bank profile shape of a stable channel. • Most influential parameters on channel geometry are studied. • A wide-ranging field dataset are used to evaluate the models. • An explicit expression for practical engineering is provided. • The proposed method can be used as an alternative in practical applications. Abstract Accurate prediction of the long-term average dimensions of alluvial stable channels is a significant problem in river engineering. The goal of this research is to investigate the effect of flow discharge (Q), mean sediment size (d 50) and Shields parameter (τ∗) on the stable channel dimensions by employing non-linear regression (NLR) and two Artificial Intelligence (AI) methods, including: Generalized Structure of Group Method of Data Handling (GS-GMDH) neural network and Gene Expression Programming (GEP). Discharge, grain size and Shields parameter from 85 gaging stations situated in three stable Iranian rivers were used as input data for the three methods to estimate the water-surface width (W), average flow depth (D) and longitudinal slope (S) of the rivers. Based on the results, it was found that the GS-GMDH produced more accurate results for simulating the channel width with a Mean Absolute Relative Error (MARE) value of 0.055; and GEP produced better estimations for channel depth and slope with MARE values of 0.035 and 0.03, respectively. Furthermore, by employing Artificial Intelligence (AI) methods (GS-GMDH and GEP), the RMSE values decreased by 22%, 25% and 75% in predicting width, depth, and slope, respectively, compared to NLR method. The overall results showed that the AI methods generally produced better estimations than the non-linear regression method. To determine the effect of each input variable (Q, d 50 , τ∗) on the target variables (W, D, S), a sensitivity analysis comprising various combinations of input variables was conducted. Based on the results, the flow discharge had a dominant role on depth and width estimation of stable channels. In slope estimation, the most important parameter was τ∗ and then d 50 , while the discharge had a weak effect on slope prediction. In general, the Shields parameter was the most effective parameter in depth and specially slope estimation of stable channels. [ABSTRACT FROM AUTHOR]

Abstract Morphodynamics of world's river deltas are increasingly affected by human activities, which are of great ecological, economic and social implications. However, impacts of human interventions in deltaic regions are insufficiently understood, especially superimposed upon diminishing sediment supplies. This study uses the heavily interfered Yangtze River delta as an example to address this issue. The morphodynamic impacts of the Deepwater Navigation Channel Project (DNCP) during 1997–2013 are investigated through process-based modeling approach (Delft3D) and bathymetric data analysis. The DNCP was implemented in the mouth bar area of the Yangtze River delta including the twin dikes and 19 groynes with the total length of 132.0 km. Hydrodynamic simulations indicate that the training walls resulted in weaker tidal flow and longer slack period at the East Hengsha Shoal (EHS) and stronger tidal flow at the subaqueous delta. Thus, the EHS is characterized as a sediment accumulation zone after the completion of the training walls. Subsequently, morphological modeling shows enhanced accretion at the EHS and enhanced erosion at the subaqueous delta when the training walls are taken into account. Numerical experiments further demonstrate that the above changes are mainly attributed to the seaward half of the northern training walls constructed in 2002–2005. This is probably the reason for the observed accretion peak of the EHS in 2002–2007 and the gradual increase in the erosion rate of the subaqueous delta after 2002. The schematized paths of sediment transport after the DNCP indicate that sediment eroded from the subaqueous delta serves as an important source for accretion of the mouth bar area. It is suggested that siltation promoting projects within the mouth bar area increased shallow shoal accretion and aggravated erosion at the subaqueous delta. With the overall erosion of the Yangtze River delta due to river sediment reduction, large-scale estuarine engineering projects substantially increase the complicacy of its morphodynamic pattern, which merits close attention for sustainable delta management. Highlights • Large-scale estuarine engineering projects complicated the overall erosion pattern induced by river sediment reduction. • Training walls in the mouth bar area strongly modified hydrodynamic field and led to adjacent accretion or erosion. • Siltation promoting projects in the mouth bar area increased shoal accretion and aggravated erosion at the subaqueous delta. [ABSTRACT FROM AUTHOR]

Flood risks are dynamically changing over time. Over decades and centuries, the main drivers for flood risk change are influenced either by perturbations or slow alterations in the natural environment or, more importantly, by socio-economic development and human interventions. However, changes in the natural and human environment are intertwined. Thus, the analysis of the main drivers for flood risk changes requires a disentangling of the individual risk components. Here, we present a method for isolating the individual effects of selected drivers of change and selected flood risk management options based on a model experiment. In contrast to purely synthetic model experiments, we built our analyses upon a retro-model consisting of several spatio-temporal stages of river morphology and settlement structure. The main advantage of this approach is that the overall long-term dynamics are known and do not have to be assumed. We used this model setup to analyse the temporal evolution of the flood risk, for an ex-post evaluation of the key drivers of change, and for analysing possible alternative pathways for flood risk evolution under different governance settings. We showed that in the study region the construction of lateral levees and the consecutive river incision are the main drivers for decreasing flood risks over the last century. A rebound effect in flood risk can be observed following an increase in settlements since the 1960s. This effect is not as relevant as the river engineering measures, but it will become increasingly relevant in the future with continued socio-economic growth. The presented approach could provide a methodological framework for studying pathways for future flood risk evolvement and for the formulation of narratives for adapting governmental flood risk strategies to the spatio-temporal dynamics in the built environment. [ABSTRACT FROM AUTHOR]

Debris loading during extreme flooding events has been documented by many post-tsunami field surveys of disaster-stricken communities and, as such, it is now considered and accounted for as a critical design consideration in the design of resilient infrastructure. Debris damming is one of the debris loads of concern, occurring when solid objects entrained within the inundating flow accumulate at the face of a structure or structural element. The presence of the debris dam results in increased drag loads on the structure and can have other associated effects, such as flow runup and flow accelerations, that can influence design conditions. The focus of debris damming studies has been within river engineering: therefore, previous studies have been performed in steady-state conditions. The study presented here is the first to examine debris damming in transient, supercritical flow conditions. The study uses a modified dam-break wave as the hydrodynamic forcing condition and the debris are scaled down debris types common in coastal areas (shipping containers, hydro poles, and boards). The analysis includes a qualitative examination of the difference in the debris damming mechanisms as a result of distinct flow conditions associated with a dam-break wave interacting with a surface-piercing obstacle. Additionally, the study determined the influence of the debris dam resulted in a maximum loading condition that occurred earlier and was of greater magnitude than the clear water case. [ABSTRACT FROM AUTHOR]

Rivers have been trained for centuries by channel narrowing and straightening. This caused important damages to their ecosystems, particularly around the bank areas. We analyze here the possibility to train rivers in a new way by subdividing their channel in main and ecological channel with a longitudinal training wall. The effectiveness of longitudinal training walls in achieving this goal and their long-term effects on the river morphology have not been thoroughly investigated yet. In particular, studies that assess the stability of the two parallel channels separated by the training wall are still lacking. This work studies the long-term morphological developments of river channels subdivided by a longitudinal training wall in the presence of steady alternate bars. This type of bars, common in alluvial rivers, alters the flow field and the sediment transport direction and might affect the stability of the bifurcating system. The work comprises both laboratory experiments and numerical simulations (Delft3D). The results show that a system of parallel channels divided by a longitudinal training wall has the tendency to become unstable. An important factor is found to be the location of the upstream termination of the longitudinal wall with respect to a neighboring steady bar. The relative widths of the two parallel channels separated by the wall and variable discharge do not substantially change the final evolution of the system. [ABSTRACT FROM AUTHOR]

Channel bars are a major depositional feature in alluvial rivers and their morphodynamics has been investigated intensively in the past several decades. However, relatively less is known about how channel bars in alluvial rivers respond to river engineering and regulations. In this study, we assessed 30-yr morphologic changes of 30 large emerged bars located in a 223 km reach of the highly regulated Lower Mississippi River from Vicksburg, Mississippi, to the Mississippi-Atchafalaya River diversion. Landsat imagery and river stage data between 1985 and 2015 were utilized to characterize bar morphologic features and quantify decadal changes. Based on bar surface areas estimated with the satellite images at different river stages, a rating curve was developed for each of the 30 bars to determine their volumes. Results from this study show that the highly regulated river reach favored the growth of mid-channel and attached bars, while more than half of the point bars showed degradation. Currently, the mid-channel and attached bars accounted for 38% and 34% of the total volume of the 30 bars. The average volume of a single mid-channel bar is over two times that of an attached bar and over four times that of a point bar. Overall, in the past three decades, the total volume of the studied 30 bars increased by 110,118,000 m 3 (41%). Total dike length in a dike field was found mostly contributing to the bar volume increase. Currently, the emerged volume of the 30 bars was estimated approximately 378,183,000 m 3 . The total bar volume is equivalent to ~ 530 million metric tons of coarse sand, based on an average measured bulk density of 1.4 t/m 3 for the bar sediment. The findings show that these bars are large sediment reservoirs. [ABSTRACT FROM AUTHOR]

This text describes the bibliography and the merits of Univ.Prof. Roland Pechlaner who passed away on May 1st 2022.' [ABSTRACT FROM AUTHOR]

Hydraulic structures, such as groyne fields, were commonly used to channelize European and North American rivers, thus forming engineered margins on the edges of the active channel. On the Rhône River (France), which was corrected with dike fields (classical groyne fields and specific ones closed with a longitudinal submersible dike; i.e., closed fields) and equipped with numerous dams (mid-twentieth century), the engineered margins have mostly been filled with fine sediments and become terrestrial. On the 11 km bypassed studied reach (middle Rhône), 55.6 ha in 167 dike fields (i.e., 75 % of the cumulated surface) have been subject to terrestrialization (i.e., the transformation of aquatic areas into terrestrial ones). Our study aimed to understand the trajectory of dike fields that serve as both drivers (e.g., inducing in-dike fine sediment trapping) and witnesses (e.g., informing the diversion impact) of hydrosedimentary changes. We combined geohistorical analyses (aerial photographs, riverbed elevations, and water levels) and GIS modeling, as well as topographic and ground-penetrating radar surveys (GPR), to emphasize the terrestrialization patterns and hierarchize the drivers and processes involved. We obtained a classification of diachronic patterns (five types) that highlight local recurrences and specificities (inherited forms) in the terrestrialization trajectory. Topographic and GPR surveys complemented our data, shedding light on the main characteristics of sediment deposits (volumes, thicknesses) and structural units. We also determined that the contribution to terrestrialization of phase 1 (channelized state; 1900s–1970s) is lower than that of phase 2 (channelized and bypassed state; 1970s–2000s), at 42 % (23.4 ha) and 58 % (32.2 ha), respectively. In phase 1, fine sediment deposition leads to deposit construction, triggered by the dike field setting, which shapes spaces with reduced shear stresses. The riverbed incision (induced by channelization) is shallow on this reach, so its contribution (by lowering the water level) is considered negligible. In phase 2, terrestrialization is mainly provoked by the diversion-induced drop in water level that has caused the retraction of the active channel and promoted its abandoned edges as new terrestrial margins. Understanding the evolution of these ecotones made it possible to adjust our recommendations in terms of management and restoration. It also highlights the relevance of strategic dike field reconnections to support the river by recreating gradients of hydrological connectivity (which are favorable to habitat diversity). • Dike fields are drivers and witnesses of contemporary river changes. • A two-phase terrestrialization triggered by channelization and flow bypass • 5 types of space-time terrestrialization patterns identified within dike fields • Distinguishing control factors: incision, dewatering and sediment deposition • Results provide new insights to guide future restoration design. [ABSTRACT FROM AUTHOR]

Sediment destruction poses a major risk to marine engineering facilities in river delta areas. The vertical deformation of seabed induced by storm surges is one of the major causes of sediment destruction. In this study, an in-situ observation system for monitoring the seabed vertical deformation was developed. The system includes a Paroscienctific high-precision water pressure sensor, a tide & wave recorder, and an Acoustic Doppler Current Profiler (ADCP). A processing method of the high-precision water pressure data was established. The advantage of this data processing method is that it allows us to obtain the water depth variation in shallow sea area based on the observed water pressure data. The system and the processing method were applied in an in-situ observation, which was carried out in Chengdao Sea area in the Yellow River Delta from December 2020 to January 2021. During this observation, marine hydrodynamic changes and vertical deformation of seabed were synchronously monitored. Three storm surge events were observed during this period. The vertical deformation process of seabed during the storm surges was quantitatively analyzed. After the first two storm surge events, the monitored vertical settlement of seabed reached 8.97 mm. A seabed vertical deformation mechanism was established based on the in-situ monitoring data. • An in-situ observation system for seabed vertical deformation was established. • A high-precision data processing method for shallow water pressure was developed. • Vertical deformation induced by storm surges was monitored in Yellow River Delta. [ABSTRACT FROM AUTHOR]

River engineering structures, such as bank protection or bed sills, act as constraints on the hydromorphology of rivers and limit morphodynamic processes. Accordingly, the deviations of a river's morphology from a natural reference condition have been attributed to the degree of artificiality in the observed river section and river restoration works mainly aimed at reducing artificial constraints within the river reach. Less attention has been drawn to alterations of the sediment continuum between sediment production in the river's catchment and downstream river reaches. However, the sediment supply from upstream is strongly reflected in the morphodynamics such as bar formation or the reworking of the riverbed. Any alteration of sediment supply may affect the morphological appearance of a reach and determine its deviation from an undisturbed condition. We introduce the Hydromorphological Evaluation Tool (HYMET), which accounts in a hierarchical procedure for sediment supply and sediment transfer as catchment and river network based preconditions for sustainable morphodynamics in river reaches. At the reach scale, artificiality and the sediment budget are assessed. In contrast to existing evaluation methods for assessing hydromorphological state, no reference condition is needed for determining hydro-morphological alterations. Here, with re-established sediment supply and reduced artificiality, a river reach is expected to develop morphodynamics that approach a morphodynamically and ecologically sustainable condition. Application to the Drau River showed that the alteration of sediment supply strongly affects the hydromorphological condition and thus the evaluation result of a restored reach, indicating the remaining potential for the re-initiation/re-establishment of morphodynamics through catchment-wide restoration plans. [ABSTRACT FROM AUTHOR]

Dams interrupt the sediment continuum in rivers by retaining the bedload; combined with flow diversion, bedload retention in tributaries and river engineering measures, this causes a bedload deficit leading to changes in river planform and morphodynamics, with potentially detrimental downstream effects. As part of the SedAlp joint project ( Sed iment management in Alp ine basins: integrating sediment continuum, risk mitigation and hydropower), this study investigates changes within a section of the dammed river Isar between the Sylvenstein reservoir and the city of Bad Tölz. We use a multi-method approach on a range of spatial and temporal scales. First, we analysed historical maps and aerial photos to analyse river planform and landcover changes within the river corridor of the whole study area on a temporal scale of over 100 years. Results show that major changes occurred before the construction of the Sylvenstein reservoir, suggesting that present morphodynamics represent the reaction to different disturbances on different time scales. Second, changes in mean bed elevation of cross profiles regularly surveyed by the water authorities are analysed in light of artificial sediment insertion and floods; they are also used to estimate the sediment budget of river reaches between consecutive cross profiles. Results suggest stability and a slight tendency towards incision, especially near the Sylvenstein reservoir; further downstream, the sediment balance was positive. Third, we acquired multitemporal aerial photos using an unmanned aerial vehicle and generated high-resolution digital elevation models to show how sediment artificially inserted in the river corridor is entrained. Depending on the position of the artificial deposits in relation to the channel, the deposits are entrained during floods of different return periods. [ABSTRACT FROM AUTHOR]

Measuring the topography of water surfaces with conventional measurement methods is, particularly in the case of turbulent flow with strong vertical and longitudinal dynamics, a very demanding and challenging task. Channel confluences are important elements in river engineering, as they appear in natural and regulated river channels, torrents, as well as in numerous hydraulic structures. At confluences, especially in the case of incoming supercritical flow, turbulent three-dimensional flows occur, and a time-varying structure of waters surface. Laser scanning enables data capture with high spatial and temporal resolution, and this method is widely used nowadays. This article discusses laser scanning as a measurement method for acquiring the agitated shape of a water surface. The application of a commercial two-dimensional LIDAR device for free-water-surface acquisition is presented for two cases. In the first case the measurements were performed in a glass tank where it was possible to determine the precise reference water level. In the second case we used LIDAR with turbulent aerated flow for fluctuating free-water surface measurement. Measurements were taken in the model of supercritical confluence, where the development of standing waves leads to the phenomenon of self-aerated flow. The measurements presented in the paper were conducted for a selected discharge rates and the Froude numbers of the main and side flow channels. Measurement results are shown as surface profiles at several selected locations of confluence. This measurement method has proven to be very promising. [ABSTRACT FROM AUTHOR]

This study comparatively analyzed the performance of water quality purification on stormwater road runoff, and the changes in the structure and composition of dissolved organic matter (DOM), after traditional ecological concrete (TEC) revetment treatment and a new improved multi-aggregate ecological concrete (IMAEC) revetment treatment. The results showed that the removal rates for chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) reached 14.56%–30.49%, 38.21%–67.96%, and 24.22%–41.14% respectively, in the TEC treatment, and 51.22%–57.90%, 64.61%–81.95%, and 40.29%–53.45% respectively, in the IMAEC treatment, suggesting that the IMAEC revetment treatment showed higher water purification performance than the TEC revetment treatment. The results of SUVA254, a 250/ a 365 and a 253/ a 203 indicated that the IMAEC treatment showed relatively high removal efficiencies of refractory aromatic compounds. Parallel factor (PARAFAC) analysis indicated that the removal rates for three fluorescent components (humic-like Components 1 and 2, and protein-like Component 3) reached 27.94%, 9.69% and 27.86 respectively, in the TEC treatment, and 51.35%, 30.10%, and 52.97% respectively, in the IMAEC treatment. 2D-COS mapping suggested that protein-like materials were more susceptible than humic-like substances, to the addition of metal ions. Protein-like materials can preferentially interact with metal ions, resulting in the effective removal of DOM-metal complexes, and can further influence the migration and transformation of metal ions. [ABSTRACT FROM AUTHOR]

An integrated indicator system was developed for determining synthetic environmental responses under multiple types of coastal reclamation engineering in the Yellow River estuary, China. Four types of coastal engineering works were analyzed, namely port construction, petroleum exploitation, fishery and aquaculture, and seawall defense. In addition, two areas with limited human disturbances were considered for comparison. From the weights of the response value for each indicator, port construction was determined to be the primary impact contributor among the four engineering works studies. Specifically, hydrodynamic conditions, ecological status, economic costs, and engineering intensity were on average 72.78%, 65.03%, 75.03%, and 66.35% higher than those of other engineering types. Furthermore, fishery and aquaculture impact on water quality was 42.51% higher than that of other engineering types, whereas seawall defense impact on landscape variation was 51.75% higher than that of other engineering types. The proposed indicator system may provide effective coastal management in future. [ABSTRACT FROM AUTHOR]

• A guideline for a proper model, inputs, and resolutions based on physical features. • This work evaluates the performance of flood models in different topographies. • Sensitivity of flood models to DEMs, modeling techniques and roughness is examined. • Main factors to get the best results with minimum computational costs are determined. • Best setting is selected for floodplain zones simulations in different topographies. Climate change leads to more severe floods, which needs to be modeled properly. This study uses two hydraulic models including Hydrologic Engineering Center River Analysis System (HEC-RAS) and LISFLOOD-FP to simulate floods in two basins (Kashkan and Missouri) with different topographies (mountain and plain terrain). The impacts of different parameters like input resolutions, Digital Elevation Models (DEMs), roughness coefficient, and modeling techniques on flood simulation are examined. Results indicate that the performance of the models varies based on topography, input resolutions, and modeling approach. Indeed, the 2D modeling of both models in different topography types leads to better results compared to 1D/2D modeling. In Kashkan basin, HEC-RAS and LISFLOOD-FP models simulate floodplain flow with accuracies of 74% and 70%, respectively, and the accuracies of the models in Missouri basin are 80% and 84%, respectively. Although both models, particularly HEC-RAS with ALOS 30 m, can provide reasonable results, with an accuracy of 74% for Kashkan and 63% for Missouri basin, LISFLOOD-FP can perform better (about 4% higher accuracy) than HEC-RAS with a higher resolution of DEM (3DEP) in Missouri basin with significantly lower computational costs. In addition, the performance of the two models significantly decreases using ASTER DEM in plain topography. Results confirm that HEC-RAS outperforms LISFLOOD-FP in coarser resolution DEMs, while LISFLOOD-FP performs better in plain topography, which requires higher resolution DEMs. Despite the low sensitivity of the two models to roughness coefficients, the variability of the LISFLOOD-FP simulations is smaller than HEC-RAS. This work uses the best setting and factors to simulate floodplain zones, which is valuable for flood risk and hazard assessment to reduce and manage damages and losses. [ABSTRACT FROM AUTHOR]

• Numerical simulation. • Debris flow. • Generalized curvilinear coordinate. Each year, structures installed in rivers and valleys (e.g., bank protections, bridges, and sabo dams) are damaged by debris flows; therefore, it is necessary to predict the flow characteristics of debris flows accurately to design river and valley structures that are robust against such debris flows. In recent years, several two-dimensional models have been developed to simulate debris flow. However, the basic equations in the numerical simulation models are in the Cartesian coordinate system, and the shape of each numerical analysis grid is square or rectangular. It is impossible to use numerical grids that match the horizontal shape of the river or valley structures, such as bank protections and sabo dams, when employing square or rectangular grids. This makes it difficult to calculate the fluid forces acting on river or valley structures. In this study, the basic equations of debris flow are provided in the generalized curvilinear coordinate system and a numerical simulation model of debris flow designed using an orthogonal curved grid along the horizontal shape of rivers and valleys is developed. Numerical simulations of a periodical meandering valley are conducted using the basic equations in the generalized curvilinear and Cartesian coordinate systems; the difference between the two results is discussed. Further, numerical simulations of the debris flow that occurred in the Kinryu River Basin in Saga City, Japan, in 2019 are performed using the basic equations in the generalized curvilinear and Cartesian coordinate systems, and the difference between the two simulation results is discussed. The numerical simulation results of debris flow in a periodical meandering channel suggest a slow propagation of debris flow when equations in the Cartesian coordinate system are used; this is attributed to the rough boundaries of debris flow when a square grid is used, which causes numerical energy dissipation that does not exist physically. The inundation areas and land surface deformation of debris flow in Kinryu River Basin were reproduced well by the developed numerical analysis model; the basic equations were written in the generalized curvilinear coordinate system. The development and decrescence of debris flows were reproduced using the developed model; the first debris flow in Kinryu River Basin was stopped in the upstream mild slope area, while the second flowed into the residential area. Reproducing the flow depth, velocity, and discharge could be improved by the model using basic equations in the generalized curvilinear coordinate system, as compared with those reproduced using basic equations in the Cartesian coordinate system. When the Cartesian coordinate system was used, the volume of the debris flow was evaluated to be small and the travel distance of the debris flow was evaluated to be short; thus, the debris flow does not arrive at the residential area and the risk of debris flows is underestimated. [ABSTRACT FROM AUTHOR]

Accurate knowledge of rainfall time distribution is a fundamental issue in many Meteorological-Hydrological studies such as using the information of the surface runoff in the design of the hydraulic structures, flood control and risk management, and river engineering studies. Since the main largest dams of Iran are in the south-west of the country (i.e. South Zagros), this research investigates the temporal rainfall distribution based on an analytical numerical method to increase the accuracy of hydrological studies in Iran. The United States Soil Conservation Service (SCS) estimated the temporal rainfall distribution in various forms. Hydrology studies usually utilize the same distribution functions in other areas of the world including Iran due to the lack of sufficient observation data. However, we first used Weather Research Forecasting (WRF) model to achieve the simulated rainfall results of the selected storms on south west of Iran in this research. Then, a three-parametric Logistic function was fitted to the rainfall data in order to compute the temporal rainfall distribution. The domain of the WRF model is 30.5N–34N and 47.5E–52.5E with a resolution of 0.08 degree in latitude and longitude. We selected 35 heavy storms based on the observed rainfall data set to simulate with the WRF Model. Storm events were scrutinized independently from each other and the best analytical three-parametric logistic function was fitted for each grid point. The results show that the value of the coefficient a of the logistic function, which indicates rainfall intensity, varies from the minimum of 0.14 to the maximum of 0.7. Furthermore, the values of the coefficient B of the logistic function, which indicates rain delay of grid points from start time of rainfall, vary from 1.6 in south-west and east to more than 8 in north and central parts of the studied area. In addition, values of rainfall intensities are lower in south west of IRAN than those of observed or proposed by the SCS values in the US. [ABSTRACT FROM AUTHOR]

In this study, we compared pre-lock-and-dam (ca. 1925) with a modern longitudinal survey of main-channel-bed sediments along a 740-km segment of the upper Mississippi River (UMR) between Davenport, IA, and Cairo, IL. This comparison was undertaken to gain a better understanding of how bed sediments are distributed longitudinally and to assess change since the completion of the UMR lock and dam navigation system and Missouri River dams (i.e., mid-twentieth century). The comparison of the historic and modern longitudinal bed sediment surveys showed similar bed sediment sizes and distributions along the study segment with the majority (> 90%) of bed sediment samples having a median diameter ( D 50 ) of fine to coarse sand. The fine tail (≤ D 10 ) of the sediment size distributions was very fine to medium sand, and the coarse tail (≥ D 90 ) of sediment-size distribution was coarse sand to gravel. Coarsest sediments in both surveys were found within or immediately downstream of bedrock-floored reaches. Statistical analysis revealed that the particle-size distributions between the survey samples were statistically identical, suggesting no overall difference in main-channel-bed sediment-size distribution between 1925 and present. This was a surprising result given the magnitude of river engineering undertaken along the study segment over the past ~ 90 years. The absence of substantial differences in main-channel-bed-sediment size suggests that flow competencies within the highly engineered navigation channel today are similar to conditions within the less-engineered historic channel. [ABSTRACT FROM AUTHOR]

Carbon cycling in inland waters has been identified as an important, but poorly constrained component of the global carbon cycle. In this study, we compile and analyze particulate organic carbon (POC) concentration data from 1145 U.S. Geological Survey (USGS) gauge stations to investigate the spatial variability and environmental controls of POC concentration. We observe substantial spatial variability in POC concentration (1.43 ± 2.56 mg C/L, mean ± one standard deviation), with the Upper Mississippi River basin and the Piedmont region in the eastern U.S. having the highest POC concentration. Further, we employ generalized linear models (GLMs) to analyze the impacts of sediment transport and algae growth as well as twenty-one other environmental factors on the POC variability. Suspended sediment and chlorophyll- a explain 26% and 17% of the variability in POC concentration, respectively. At the national level, the twenty-one environmental factors combined can explain ca. 40% of the spatial variance in POC concentration. At the national scale, urban area and soil clay content show significant negative correlations with POC concentration, whereas soil water content and soil bulk density correlate positively with POC. In addition, total phosphorus concentration and dam density correlate positively with POC concentration. Furthermore, regional scale analyses reveal substantial variation in environmental controls of POC concentration across eighteen major water resource regions in the U.S. The POC concentration and associated environmental controls also vary non-monotonically from headwaters to large rivers. These findings indicate complex interactions among multiple factors in regulating POC concentration over different spatial scales and across various sections of the river networks. This complexity, together with the large unexplained uncertainty, highlights the need for considering non-linear interplays of multiple environmental factors and developing appropriate methodologies to track the transformation and transport of POC along the terrestrial-aquatic interfaces. [ABSTRACT FROM AUTHOR]

In the Danube River Basin multiple pressures affect the river system as a consequence of river engineering works, altering both the river hydrodynamics and morphodynamics. The main objective of this paper is to identify the effects of hydropower development, flood protection and engineering works for navigation on the Danube and to examine specific impacts of these developments on sediment transport and river morphology. Whereas impoundments are characterised by deposition and an excess of sediment with remobilisation of fine sediments during severe floods, the remaining five free flowing sections of the Danube are experiencing river bed erosion of the order of several centimetres per year. Besides the effect of interruption of the sediment continuum, river bed degradation is caused by an increase in the sediment transport capacity following an increase in slope, a reduction of river bed width due to canalisation, prohibition of bank erosion by riprap or regressive erosion following base level lowering by flood protection measures and sediment dredging. As a consequence, the groundwater table is lowered, side-arms are disconnected, instream structures are lost and habitat quality deteriorates affecting the ecological status of valuable floodplains. The lack of sediments, together with cutting off meanders, leads also to erosion of the bed of main arms in the Danube Delta and coastal erosion. This paper details the causes and effects of river engineering measures and hydromorphological changes for the Danube. It highlights the importance of adopting a basin-wide holistic approach to river management and demonstrates that past management in the basin has been characterised by a lack of integration. To-date insufficient attention has been paid to the wide-ranging impacts of river engineering works throughout the basin: from the basin headwaters to the Danube Delta, on the Black Sea coast. This highlights the importance of new initiatives that seek to advance knowledge exchange and knowledge transfer within the basin to reach the goal of integrated basin management. [ABSTRACT FROM AUTHOR]

[Display omitted] • Close-range aerial surveying of large wood (LW) accumulations in the field. • Employing digital twin models (3D replicates) for the assessment of wooden deposits. • Accurate 2.5D and 3D volumetric measurements eliminate traditionally induced errors. • Obtaining solid cubic meter (solid wood) volume of prototype LW accumulations. • Approximation of LW accumulation porosity from digital twin models. Quantification and assessment of large wood (LW) accumulations in fluvial systems is still considered difficult due to the complex nature of wooden deposits. Although knowledge about volumetric measures and porosity parameters of LW accumulations is crucial for the prediction of hydraulic and geomorphic effects, it has not yet been possible to obtain accurate measurements. These limitations are mainly based on a lack of applicable sensing technologies available in the past. In the present study, a close-range aerial surveying technique (Structure from Motion (SfM) photogrammetry) is applied for generating 3D replicates (digital twin models) of wooden deposits, enabling their volumetric assessment. In addition, manually conducted volumetric measurements of corresponding prototype LW accumulations help to improve and calibrate the SfM-derived estimates. For the first time, precise porosity parameters for LW accumulations, ranging from 52.5 to 83.2%, are provided. In addition, a novel parameter – the packing arrangement – is used, which describes the structural alignment of individual elements in the LW accumulation and benefits porosity estimates based on the applied 2.5D and 3D photogrammetric approach. Accordingly, randomly and loosely organised LW accumulations allow for a high penetration depth of the 3D approach, resulting in a more accurate estimate of the actual porosity, as the 3D volumetric estimate approaches the solid wood volume of the corresponding LW accumulation. An empirical approach has been developed for future approximation of LW accumulation porosity, without the need of knowing the solid wood volume. With the present work a significant improvement of our understanding in employing a non-intrusive sensing technique is provided, linked with manually conducted field measurements of the solid wood volume of LW accumulations. Our study contributes to an improved data acquisition and processing plan, which represents a further important step towards a systematic assessment framework that is urgently needed by river managers and engineers to better evaluate and manage LW in fluvial systems. [ABSTRACT FROM AUTHOR]

• A fully-three-dimentional scouring numerical model is developed to investigate the flow and sediment motion in the grouped spur dikes system built in river engineering for the purposes of environmental protection and ecological conservation. • The flow properties, sediment moving and geomorphology in two sets of grouped spur dike cases with most commonly used layout styles, namely the normal-angled spur dikes case and the 45 degree downward-angled spur dikes case are discussed based on the simulation results. • The influence of flow conditions, sediment parameters and spur dike layout angles on the maximum scour depth and their coordinates are analyzed through amounts of additional simulations, which could offer guidance for the structure safety and protection project construction. • The simulations of flood passage through the spur dike fields are conducted to demonstrate the dynamic process of sediment transport and scour development under an unsteady flow condition. The flow properties, sediment moving and geomorphology in the grouped spur dikes field have always been of interest in river engineering. In this paper, a 3D numerical model is employed to investigate the flow motion and riverbed scouring around grouped spur dikes with different layout angle styles. Series of flume experiments are introduced to verify this model's reliability before its application on the simulation of the downward-angled spur dikes case and normal-angled spur dikes case respectively, and detailed comparative analyses on the flow intensity, vortex patterns and local scour are made for these two layout angle styles respectively, in which the similarities and differences could both be found. Then the influence of flow conditions, sediment parameters and spur dike layout angles on the maximum scour depth and their coordinates are discussed through additional simulations, while the different correlations show between the maximum scour depths with these three factors. Then the simulation of flood passage through the spur dike fields is conducted, which could not only provide river hydrological information but also offer guidance for the hydraulic structure safety. [ABSTRACT FROM AUTHOR]

The increase in impervious surfaces caused by urbanization and the frequency of precipitation events resulting from climate change significantly impact the hydrological and geomorphological processes of urban watersheds. Landscape changes caused by urban development may affect surface/groundwater generation and circulation processes. In-depth research on the relationship between landscape changes and runoff is a precondition of urban watershed restoration and stormwater management. Taking the Yangmei River Basin as the study area, the storm water management model (SWMM), landscape index, correlation analysis, and the random forest importance measure were integrated to simulate the runoff process under urban development and climate change scenarios and analyze the direction and contribution of landscape composition and configuration to runoff changes. Results indicated that the runoff change rate relative to the reference period under the RCP 4.5 and RCP 8.5 scenarios gradually decreased as the return period increased. Landscape composition and configuration were significantly correlated with runoff change. Specifically, woodland could reduce runoff, while farmland and water bodies positively impacted runoff changes. The higher fragmented landscape pattern was likely to have altered the runoff, while landscape patterns of a larger size, higher concentrations, and a declining richness typically reduced runoff. The random forest importance evaluation demonstrated the significant contributions of Patch Density, Shannon's Diversity Index, and Large Path Index to runoff. By exploring the potential relationship between landscape changes and runoff, urban planners can better understand the runoff process and find feasible ecological landscape optimization schemes, thus strengthening the sustainable management of water resources and enhancing the resilience of cities to climate change. • Correlation between landscape pattern and runoff change was determined. • Random forest was used to study the contribution of landscape metrics to runoff. • Landscape metrics that contribute significantly to runoff changes were identified. • Watershed stormwater management approach based on landscape pattern optimization. [ABSTRACT FROM AUTHOR]

• "central bar formation" and "channel avulsion" are the main river evolution mechanism in the simulated gravel-bed reach. • As the river width expands downstream, the longitudinal profile gets stable, while the transverse oscillation becomes wild. • If the longitudinal structure (bank revetment) on the concave bank of a gravel-bed river is made by concrete with relatively smooth surface, it is very likely to cause further damage on the longitudinal structure. Due to a steep slope, rapid flow, and large amounts of sediment, rivers in Taiwan are braided rivers that are full of bars and bifurcated flows. The channel shifting behavior and bar migration within natural braided rivers results in difficult river engineering. In this study, the Nays2DH model was used to simulate the braiding processes and morphological changes downstream of Shigang Dam in the Da-jia River from 2012 to 2013. Furthermore, the characteristics of riverbed erosion, the stability of the channel in the longitudinal and transverse directions and the impact of river structures on the morphology were simulated. The numerical model can present morphological and evolutionary processes similar to an actual river, such as: central bar formation, chute cutoff, and channel avulsion. The scour pool mostly occurred at the apex of the river bend and downstream of the bar (confluence) in a braided river, which means that bar migration is the main factor that alters scour position. Under the assumption of equilibrium sediment transportation across the upstream inflow section, the width of the channel determines whether the river demonstrates longitudinal erosion or transverse changing. Results from this research can be used as a substantial reference for future research concerning river morphology evolution, river engineering, and river space planning. [ABSTRACT FROM AUTHOR]

Ecological restoration has been risen to a national strategic project for China and become an significant way to realize ecological civilization construction. As an important way to measure the effectiveness of ecological restoration engineering, the corresponding evaluation provides a reliable basis for ecological restoration decision-making and ecosystem management. Based on remote sensing technology with the advantages of short revisit time, large monitoring range, high spatial resolution, this paper proposes a remote sensing evaluation method of watershed ecological restoration effect, so as to monitor the implementation effect of ecological restoration engineering in the watershed and technically check whether the expected goals set before the restoration are achieved. The comprehensive ecological restoration engineering of Yongding River has been implemented since 2016, and it was the first focus of the coordinated development of Beijing-Tianjin-Hebei region to make advances in ecology. In this paper, year 2015 and 2020 were selected as the before and the after the ecological restoration engineering of Yongding River. The research object was the riparian zone from Luopoling Reservoir to Daning Reservoir in Yongding River Watershed. After obtaining and processing remote sensing images, ZY-3 images were used to obtain land cover data by means of human-computer interactive interpretation, and Landsat images were used to retrieve NDVI data. Based on these data, the changes of the eight indicators of water resources, water ecology and ecological function in the study area were calculated to evaluate the ecological restoration engineering effect. The results showed that the study area has basically realized the maintenance of ecological water quantity, formed the ecological corridor of Yongding River, and effectively enhanced the ecological function and improved the water environment. By verifying the feasibility of remote sensing evaluation method, this paper could provide relevant decision makers and planners with an effective evaluation method for the ecological restoration engineering effect based on remote sensing data and technology. • Remote sensing images and land cover data were utilized to calculate the indicators before and after ecological restoration. • Ecological restoration engineering effect was evaluated from water resources, water environment and ecological function. • Based on the proposed method, the ecological restoration effect in the study area was proved to be satisfactory overall. [ABSTRACT FROM AUTHOR]

Assessment and quantitative description of river morphology using widely recognized river planview measures (e.g., length, width and sinuosity of channels, bifurcation angles and island shape) for multichannel rivers are regarded as fundamental parts of the toolkit of geomorphologists and river engineers. However, conventional assessment methods including field surveys or exiting algorithms for the extraction of multichannel planviews might be suboptimal. More recently, the potential for the application of complex network analysis to the study of river morphology has led to emphasis on the accurate characterization and definition of multichannel network topology. Therefore, we developed a novel algorithm called RivMACNet (River Morphological Analysis based on Complex Networks) that enables the extraction of multichannel network topology using satellite sensor images as the input. We applied RivMACNet to a meandering reach of the Yangtze River and a strongly anastomosing reach of the Indus River to construct their network topologies, and then calculated a series of common topological measures including weighted degree (WD), clustering coefficient (CC) and weighted characteristic path length (WCPL). The network analysis indicated that both networks exhibit poor transitivity with small clustering coefficients. The topological properties of the Indus at the reach scale are independent of flow conditions, while they vary across space at the subnetwork scale. In addition, comparison between RivMACNet and an alternative common river network analysis engine (RivaMap) demonstrated that RivMACNet is superior in terms of representation accuracy and network connectivity and, thus, is more suitable for multichannel fluvial systems with complex planviews. RivMACNet is, thus, a useful tool to support further investigation of multichannel river networks using graph theory. • RivMACNet automates construction of multichannel network topology and extracting geometrical and topological measures. • Presents a case study on an anastomosed reach of the Indus River that demonstrates the application of RivMACNet. • River topological reach scale properties and their spatial distributions were analyzed for the study reach. • RivMACNet is more sensitive to islands and sand bars in multichannels, and can guarantee network connectivity. [ABSTRACT FROM AUTHOR]

This article focuses on assessing the habitats characteristics of endangered Calamagrostis pseudophragmites in selected localities in the Czech Republic with different river engineering measures, which can potentially influence the occurrence of this species. Furthermore, we give some general recommendations for management practices based on our results to promote the conservation of Calamagrostis pseudophragmites . Our research shows that there is a high correlation between Calamagrostis pseudophragmites and natural or near natural sunny biotopes on gravel bars or straight reaches near the water level that consist of non-silted gravel substrates with a higher concentration of pebbles or cobbles, which are typical of piedmont and mountain-valley areas. Many of these areas are rapidly disappearing due to intensive anthropogenic pressure. We also found that Calamagrostis pseudophragmites is temporarily capable of surviving among other competitively stronger plant communities. To assess the potential influence of river engineering we selected two different types of rivers where this species is present – one was heavily altered by both the construction of a water reservoir in its upper reach and channelization of the stream, the other was less severely regulated by the construction of several weirs. Our results show differences in the occurrence of Calamagrostis pseudophragmites between the two rivers, being found at three times as many localities in the less regulated river than in the more regulated one. This corresponds with a higher number of gravel bars in the less regulated river. Based on our results, our general recommendations for the management of this species include only the partial removal of gravel bars (to ensure flood control in populated areas), blocking vegetation succession by removing woody vegetation and aggressive invasive species, the restoration of natural river dynamics, and connecting existing biotopes where this species is found. [ABSTRACT FROM AUTHOR]

Rivers and floodplains are among the most species-rich ecosystems in Middle Europe. Intensive anthropogenic influence has led to a loss of floodplain area and threatens their ecological functionality. This is especially the case for waterways, which have been subject to river engineering due to their economic importance and thus have lost a significant amount of their original floodplains and biodiversity. Canals as artificial waterways have been in the focus of reconciliation ecology, and they have been proven to serve as a refuge for several aquatic species groups where their original habitat is impaired or lost. However, the potential to preserve terrestrial macrophytes and biodiversity along their banks has rarely been considered. Thus the question arises whether canals can provide, at least partly, suitable habitat space to sustain species diversity and functionality of floodplains. In the present case study, we compared the floristic, functional and structural diversity of the floodplain and the respective adjacent areas of the river Ems and the Dortmund–Ems canal in North Western Germany, since both waterways run in parallel and are hydrologically connected. Species composition shows distinct differences between both waterways. Most species along the canal are mainly generalists adapted to anthropogenic influence, while species along the river are characteristic for floodplain systems. Species diversity is up to 10% higher along the canal due to higher lateral heterogeneity, while functional divergence and landscape structure diversity are up to 5% higher along the natural river. Diversity distribution patterns are mainly influenced by landscape structure and land use patterns. Numbers of endangered species did not differ significantly. Thus, the canal can serve as a habitat for single endangered floodplain species but it cannot substitute the functions of a natural dynamic floodplain. Increasing structural diversity and preserving the habitat function of the canal banks by an adapted management regime might enhance the ecological value of a heavily used artificial waterway within the given economic limitations. [ABSTRACT FROM AUTHOR]

• A new type of integral hydrophobic admixture was developed. • The durability of HA and mortar with HA was systematically investigated. • The inhibition mechanism of bi-directional water migration was revealed. The sulfate attack tends to cause deterioration in the performance of cement-based materials. An innovative hydrophobic agent named Yellow River Engineering Consulting (YREC) was developed to improve the resistance of the mortar to sulfate attack in wet-dry cycling environment. In this study, an investigation was conducted to investigate the effects of the acid, alkali and salt solutions on the durability of the YREC. Meanwhile, a series of hydrophobic mortars with varying YREC mass fractions were prepared to explore the sulfate resistance in the wet-dry cycling environment. The water migration in wet and dry process was compared by conducting the water absorption and desorption tests. In addition, the XRD, FTIR, ESEM and MIP were applied to further analyze the properties of the YREC. According to the analytical results, the microstructure and hydrophobic functional group of the YREC remained unchanged under the erosion of the acid, alkali and salt solutions. The YREC could significantly reduce the surface cracking, strength loss and structural loosening of the mortar under the wet-dry cycling sulfate attack. In addition, the YREC played a role in reducing the rate of the water absorption and desorption, resulting in a decrease in the sulfate concentration and penetration depth. Finally, the mechanism analysis showed that the YREC could enhance the inhibitory effect on bi-directional water migration through hydrophobization and refining the pore structure of the mortar. [ABSTRACT FROM AUTHOR]