Measurements Of Sediment Transport Research Articles

Morfológiai vizsgálatok Magyarország délnyugati határfolyóin = Morphological Studies on South-Western Border Rivers in Hungary

Nowadays, the preservation and sustainable use of our natural values are increasingly coming to the fore, and this has implications not only for economic and field development but also for ecological aspects. In recent years, attention has shifted towards river morphological studies, which were previously relegated to the background. Understanding long-term changes and assessing the current state is essential to estimate future processes. In this article, we present our morphological studies on the Hungarian–Croatian border sections of the Mura and the Drava rivers. Historical changes were analyzed through a comparative study of historical maps from earlier periods, while the evaluation of the current state was conducted based on a detailed terrain model from a recent survey. GIS evaluation was also compared with sediment transport and flow measurement results. This comparison suggests that the morphological status of the river section under study is consistent with the typical parameters of transport processes.

Measurement and Calculation of Sediment Transport on an Ephemeral Stream

Sediment transport remains a significant challenge for researchers due to the intricate nature of the physical processes involved and the diverse characteristics of watercourses worldwide. A type of watercourse that is of particular interest for study is the ephemeral streams, found primarily in semiarid and arid regions. Due to their unique nature, a new measurement algorithm was created and a modified bed load sampler was built. Measurement of the bed load transport rate and calculation of the water discharge were conducted in an ephemeral stream in Northeastern Greece, where the mean calculated streamflow rate ranged from 0.019 to 0.314 m3/s, and the measured sediment load transport rates per unit width varied from 0.00001 to 0.00213 kg/m/s. The sediment concentration was determined through various methods, including nonlinear regression equations and formulas developed by Yang, with the coefficients of these formulas calibrated accordingly. The results demonstrated that the equations derived from Yang’s multiple regression analysis offered a superior fit compared to the original equations. As a result, two modified versions of Yang’s stream sediment transport formulas were developed and are presented to the readership. To assess the accuracy of the modified formulas, a comparison was conducted between the calculated total sediment concentrations and the measured total sediment concentrations based on various statistical criteria. The analysis shows that none of Yang’s original formulas fit the available data well, but after optimization, both modified formulas can be applied to the specific ephemeral stream. The results indicate also that the formulas derived from the nonlinear regression can be successfully used for the determination of the total sediment concentration in the ephemeral stream and have a better fit compared to Yang’s formulas. The correlation from the nonlinear regression equations suggests that total sediment transport is primarily influenced by water discharge and rainfall intensity, with the latter showing a high correlation coefficient of 0.998.

Impact of temporal beach grain size variability on aeolian sediment transport and topographic evolution in a microtidal environment

While the impact of the spatio/temporal variability of grain size on morphological beach state is reasonably well understood, relatively little is known on its impact at a scale of days/months on aeolian sediment transport. This study focuses on five short intensive wind events during which aeolian sediment transport measurements, beach surface sampling and elevation change surveys were carried out for 1 to 3 days, over a 16-month period on a microtidal beach dominated by offshore winds. Monthly observations show a high temporal variability in beach grain size in relation to the decoupling between hydrodynamic and aeolian processes, from medium sand after a marine storm and inundation of the beach, to very coarse sand after several weeks of storm-force winds. During each wind event, topographic change on the beach ranged from zero, to 0.55 m. The time scale of coarsening depended on the initial beach grain size and could be very fast when the beach was composed of medium sand (e.g. 388 μm sand changed to coarse sand of 547 μm in 40 h). In contrast, it took one month to transition from a coarse median beach grain size of 883 μm to a very coarse one of 1323 μm. This variability in grain size results in dramatically different rates of sediment flux. For example, during average wind speeds of 10 to 14 m/s the sediment flux when the beach was composed of medium sized sand ranged between 21 and 154 kg/m/h compared to 0.4 to 50 kg/m/h when the beach was composed of coarse and very coarse sized grains. Overall, this study highlights the importance of beach grain size variability on aeolian sediment transport and shows that for similar incident wind and climatic conditions aeolian sediment transport rates vary dramatically. The study demonstrates the importance of taking care when using a constant median grain size in the calculation of long-term aeolian sand transport on beaches with heterogeneous spatial and temporal beach grain size variability.

Testing magnetic tracers as indicators of sediment transport in a wave flume experiment

AbstractThe in situ measurement of sediment transport in wave‐dominated environments presents significant challenges and currently often relies upon the use of fluorescent sediment tracers. However, this method is constrained by challenges in conducting unbiased and representative sampling, as well as facing overall logistical complexities and labour‐intensive procedures. Whilst other tracer techniques are available, such as using magnetic tracers, their performance in tracking sediment transport has not been quantified. The objective of this study is to assess the effectiveness of magnetic tracers in evaluating net transport rates and tracer dispersal patterns. Conducted in a controlled large wave flume, the experiments simultaneously employed fluorescent and magnetic tracers, allowing a comprehensive comparison of the tracers' dispersion patterns and the net transport rates. Results show that the dispersal of magnetic and fluorescent tracers displays a high degree of spatial coherence in both horizontal and vertical dimensions. Similarly, net transport rates are comparable (<16% difference), both showing net transport in the direction of the wave propagation (towards onshore) driven by non‐linear and streaming effects. Magnetic tracer recovery rate (49%) was lower than for fluorescent tracers (73%) and is attributed to the loss of magnetic ink from particles; an aspect of the magnetic technique that requires improvement. This study therefore indicates that the use of magnetic tracers to quantify sediment transport is an effective method with the advantages of being significantly less labour‐intensive than using the commonly applied fluorescent sediment tracer method.

Assessment of plot-scale sediment transport on young moraines in the Swiss Alps using a fluorescent sand tracer

Abstract. Glacial retreat uncovers large bodies of unconsolidated sediment that are prone to erosion. However, our knowledge of overland flow (OF) generation and sediment transport on moraines that have recently become ice-free is still limited. To investigate how the surface characteristics of young moraines affect OF and sediment transport, we installed five bounded runoff plots on two moraines of different ages in a proglacial area of the Swiss Alps. On each plot we conducted three sprinkling experiments to determine OF characteristics (i.e., total OF and peak OF flow rate) and measured sediment transport (turbidity, sediment concentrations, and total sediment yield). To determine and visualize where sediment transport takes place, we used a fluorescent sand tracer with an afterglow as well as ultraviolet (UV) and light-emitting diode (LED) lamps and a high-resolution camera. The results highlight the ability of this field setup to detect sand movement, even for individual fluorescent sand particles (300–500 µm grain size), and to distinguish between the two main mechanisms of sediment transport: OF-driven erosion and splash erosion. The higher rock cover on the younger moraine resulted in longer sediment transport distances and a higher sediment yield. In contrast, the higher vegetation cover on the older moraine promoted infiltration and reduced the length of the sediment transport pathways. Thus, this study demonstrates the potential of the use of fluorescent sand with an afterglow to determine sediment transport pathways as well as the fact that these observations can help to improve our understanding of OF and sediment transport processes on complex natural hillslopes.

Field-Measurement of Surface Wind and Sediment Transport Patterns in a Coastal Dune Environment, Case Study of Cala Tirant (Menorca, Spain)

Blowouts are integral features of coastal dune fields. Their presence enhances both geomorphological and ecological diversity and enables the movement of sand by wind. Their role as a ‘transport corridor’ may be, however, considered negative from a coastal management perspective in heavily touristic areas, where the existence of blowouts close to the foredune can enhance the loss of sediment from the beach. This paper investigated the relationship between airflow dynamics and patterns of sediment transport from the beach to established dunes through a trough blowout located on the foredune. Seven three-cup anemometers were used to measure wind speed and direction over a 24 h sampling period at a frequency of 1 min under onshore (parallel to the blowout axis) medium and high wind speeds (max of 17.9 ms−1). To measure sediment transport, a total of 12 vertical sand traps were located at three positions along the length of the deflation basin. The results indicated that small amounts of sediments went into the blowout from the beach and that the highest rates of sediment remobilization took place within the deflation basin. These results highlight two processes: (a) flow channelization induced by the blowout topography caused an increase in wind speed and sediment transport toward the depositional lobe, and (b) the presence of embryo dunes and herbaceous vegetation at the beach–blowout boundary effectively reduced the amount of sediment transport from the beach to the landform. The results confirmed the significant role that vegetation plays in controlling sediment movement and conserving the beach–dune system.

Trapping of fine-grained sediment on a supply-limited intertidal shore platform at Kaikōura, New Zealand

Shore platforms are generally supply-limited environments and few studies have attempted to measure sediment transport within this rock coast setting. This paper summarises a field-based pilot study that successfully collected fine-grain sediment moving across a sub-horizontal platform at Mudstone Bay, Kaikōura, New Zealand. Two large-aperture and two small-aperture Time-Integrated Mass-sediment Samplers (TIMS) were deployed for 9-days, encompassing 2 days of storm conditions (offshore significant wave heights between 2.0 and 3.6 m, with sediment trapped in both landward and seaward facing directions. The net flux of sediment captured in large aperture samplers was greatest in a seaward-direction (15.2 g), whereas the narrow-mouth samplers, that principally collected suspended sediment had a net onshore flux (5.4 g). The sediment traps yielded sufficient sample to undertake geochemical and textural analysis. Interpretation of these data suggests that the origin of transported material was autochthonous to the platform, being >80 % silt-sized and compositionally consistent with material derived from the shore platform and/or cliff colluvium. This pilot experiment demonstrates that mass-sediment samplers can be used in supply-limited intertidal shore platform settings. Further research involving greater sampling frequency and duration and concomitant detailed hydrodynamic measurements are likely to reveal important insights into the erosion environment.

Field Measurements of Longshore Sediment Transport along Denu Beach, Volta Region, Ghana

Field measurements of longshore sediment transport have been performed in the surf zone along Denu Beach, located in the Volta Region of Ghana, West Africa. This study consisted of measuring sediment transport rates by the deployment of modified versions of Kraus streamer traps on a cross-shore distance, which was about half the average surf zone width. In addition to the measured transport rates, data on waves, longshore currents, and other morphological parameters were collected with simple and low-cost instrumentation. In total, about 22 datasets were obtained through several days of data collection spanning a period of 5 months. Mathematical formulae proposed by CERC (1984), Kamphuis (1991), and the new van Rijn (2014) were used to compute theoretical transports for the entire surf zone, which were validated by measured data. Applying the CERC equation with a K-value of 0.39, the theoretical transports were about one order of magnitude higher than the measured rates. The rates computed by the Kamphuis formula were slightly higher than those yielded by the van Rijn equation. They produced values that were, on average, about 3.5 and 2.9 times higher than the measured rates, respectively. This study then confirmed the capabilities of both the Kamphuis and van Rijn equations to provide closer estimates of longshore sediment transport on Denu Beach. It especially sheds light on the new van Rijn formula, which has not been used extensively in LST quantification across the world. We, therefore, concluded that both the Kamphuis and van Rijn equations could be particularly useful to local engineers in the prediction of LST prior to the design of coastal protection structures. Further long-term studies employing available cutting-edge technologies were also recommended to provide more information on longshore transport not only in Ghana but also in the entire Gulf of Guinea and for the establishment of a reliable sediment budget for the country and the entire region.

Sediment modeling using laboratory-scale rainfall simulator and laser precipitation monitor

The characterization of a rainfall simulator provides an excellent opportunity to study the potential of soil erosivity without waiting for natural rain. But, precise instrumentation is required to estimate the parameters, which is seldom available. To overcome this problem, the empirical and conceptual relationships obtained through physically-based modeling help to correlate the rain parameters contributing to soil erosion. The present laboratory study used five pressurized nozzles of different capacities and a Laser Precipitation Monitor (LPM) to generate different rain intensities (21.0–79.0 mm h−1) and to register drop size distribution, respectively. The sediment transportation induced by rain and runoff was measured with an erosion flume of 2.50 × 1.25 × 0.56 m with an adjustable longitudinal slope. The spatial uniformity, drop size distribution, drop velocity, and kinetic energy were used to evaluate the simulator's performance. The different rain erosivity parameters were correlated and tested statistically using linear and non-linear regression analysis. The rain simulation experiments of different intensities at different pressure ranges were performed on flat, 5, 10, and 15% slopes of the erosion flume to evaluate rain characteristics and record the surface runoff and sediment yield. The median drop sizes produced during the simulator ranged from 0.38 to 2.11 mm, coinciding with natural rain. The empirical relationships were developed to correlate surface discharge and sediment yield with rain intensity by optimizing the parameters for further study of experimental field plots of different slopes. The observed and estimated rain erosivity parameters showed a significant relationship (R2 = 0.75 to 0.93; P < 0.001) in multiple regression analysis, and the metrics used to test the developed regression equations showed lower MAE, MSE, and RMSE errors indicating the adequacy of the relationships. The results indicated that the simulator helps to understand the complex task of soil erosion with hydrologic and geomorphic processes in laboratory experimentation with sufficient accuracy in measuring sediment transport events.

Proglacial slopes are protected against erosion by trait diverse and dense plant communities associated with specific microbial communities

Soil erosion is a severe threat for ecosystems and anthropogenic infrastructure. Glaciers are retreating rapidly due to global warming and the receding ice leaves unvegetated depositions of sediment, which are prone to mobilisation during precipitation events. Vegetation is known to serve as erosion protection, but how above- and belowground plant traits, vegetation cover and plant diversity on community level are jointly affecting erosion is unclear. Additionally, soil microbial communities may have effects on slope stability by promoting plant growth and function. We measured sediment transport on 30 plots of 2 × 3 m size on proglacial slopes of the Gepatschferner glacier (Kaunertal, Austria) over three years in a natural pristine high alpine environment. Vegetation cover, species abundances and relevant above- and belowground traits were measured for each occurring plant species on community level. Path model analysis revealed that dense and species-rich plant cover characterized by specific plant growth strategies and trait diversity was best suited to decrease erosion. Vegetation properties were also closely linked to the composition of soil microbial communities characterised by next generation amplicon sequencing, which may facilitate soil formation and further enhance the plants’ soil stabilising potential. Our study illustrates that erosion control may benefit from a high vegetation cover, which is facilitated by diverse plant communities with complementary morphological traits. These vegetation properties also affect soil microbiota, but their impact on slope protection in combination with the vegetation remains to be elucidated. Our findings may inform nature-based solutions against erosion such as revegetation of alpine slopes using specific seed mixtures.

A century of channel change caused by flow augmentation on Sixth Water Creek and Diamond Fork River, Utah, USA

AbstractThe Diamond Fork River in central Utah, USA experienced extreme flow augmentation via transbasin flows. Beginning in 1916, irrigation water was delivered through a tributary, Sixth Water Creek, with daily summer flows regularly exceeding a 500‐year flood at the point of introduction. Flows were dramatically reduced by management action in 2004 but with mandated minimum flows. We examined the geomorphic response of Sixth Water and Diamond Fork using aerial imagery, lidar, topographic cross sections, and sediment transport measurements. River channel response varied with valley confinement and with position in the watershed, which determined the magnitude of augmented flow relative to natural floods and the amount of sediment supply. Confined, steep sections of Sixth Water incised many meters into bedrock, whereas partially confined and unconfined sections developed a braided form even under conditions of general incision. With the removal of flow augmentation, smaller natural floods on Sixth Water are unable to transport bed material and the channel remains static. On the alluvial lower Diamond Fork, a lower slope, upstream sediment supply, and larger natural floods produced a dynamic shifting channel that widened in response to natural floods. After flow augmentation, a coarsened bed is partially mobile and channel narrowing appears to be limited by artificial baseflow, which prevent vegetation establishment in the channel.

Measuring Sediment Transport Capacity of Concentrated Flow with Erosion Feeding Method

Sediment transport capacity in rills is an important parameter for erosion modeling on hillslopes. It is difficult to measure, especially at gentle slopes with limited rill length. In this study, a special flume with variable slope gradients in upper and lower sections was implemented to measure the sediment transport capacity. The upper flume section with a higher slope gradient generates faster water flow that could scout more sediment to feed the water flow in the rill. The rest of the flume is set at the designated slopes to measure the transport capacity in different slope and runoff conditions. A series of flume experiments were conducted with silt-loam soil to verify the method. The sediment transport capacity was measured under slope gradients of 5°, 10°, 15°, 20°, and 25° and a flow rate of 2, 4, 8, and 16 L min−1. The measured sediment transport capacity values were compared with reference measurements from other rill erosion experiments with similar materials and setups. At high slope gradients of 15°, 20°, and 25°, the newly suggested method produced almost the same transport capacity values. Under the low slope gradients of 5° and 10°, the maximum sediment concentrations from the 8 m long flume with the uniform gradients in the previous experiments, rill erosion with an 8 m long flume produced were about 36% lower than the values measured with the new method, which is insufficient to make the flow reach sediment transport capacity. The sediment transport capacities at lower slopes measured with the new method followed the same trend as those at higher slopes. The new method can supply enough sediments to ensure the flow approach transport capacity measurement and, therefore, provides a feasible approach for estimating sediment transport capacity for conditions with relatively gentle slopes.

Observations and modeling of shear stress reduction and sediment flux within sparse dune grass canopies on managed coastal dunes

AbstractWind flow over coastal foredunes adapts to vegetation, resulting in spatial gradients in bed shear stresses that contribute to the formation of localized bedforms. Understanding, and having the capability to numerically predict, the distribution of sediment deposited within sparsely vegetated dune complexes is critical for quantifying the ecological, protective, and economic benefits of dune management activities. Data from wind tunnel experiments have indicated that there is a spatial lag from the canopy leading edge to a downwind location where sediment deposition first occurs. The length scale of this deposition lag is further quantified here using new field measurements of aeolian sediment transport across sparsely vegetated managed dune systems in Oregon, USA. We develop a deposition lag length scale parameter using both lab and this new field data and then incorporate this parameter into the process‐based aeolian sediment transport model, Aeolis, which also includes a new far‐field shear stress coupler. Results from numerical simulations suggest that the spatial deposition lag effect is significant for model skill in sparsely vegetated dunes. We observe with field and laboratory observations that, as canopy density increases, the length of the deposition lag decreases. As such, within the model framework the implementation of the deposition lag length does not affect the results of models of coastal dune geomorphological evolution within higher density canopies. Dune canopy density can vary due to natural (e.g., storm overwash, burial, die‐off) or anthropogenic (e.g., managed plantings, dune grading) processes.

Application of Delft3D computational model to estimate the influence of El Bala run-of-the-river dam on the morphological activity of Beni River, Bolivia

Beni river is an important tributary in the Amazon basin. There, the Bolivian government decided the construction of a two-dam cascade hydropower system, including Chepete dam and El Bala run-of-the-river dam. The main concern is the high sediment transport in Beni river. Then, the aim of the research is the application of Delft3D model to estimate the influence of El Bala run-of-the-river dam on the sediment transport and morphological activity of Beni river. The model was calibrated for natural conditions based on ADCP data and sediment transport measurements collected from the river. The implemented model was able to reproduce hydrodynamics and sediment transport in natural conditions. Hence, several scenarios were tested. A hydrodynamic and morphological model was set to test the influence of the dam on the river for hydrodynamics, sedimentation and erosion processes in Beni river. Results show that Delft3D performed very well in modelling sedimentation and erosion processes in Beni river, the model was able to predict the expected erosion process due to the presence of Chepete dam, upstream of El Bala, which retains the sediment load of Beni river affecting the morpho-dynamics of the river. Additionally, the model was able to predict a sedimentation in the reservoir.

Tidal Sediment Supply Maintains Marsh Accretion on the Yangtze Delta despite Rising Sea Levels and Falling Fluvial Sediment Input

Tidal marshes are among the world’s most valuable ecosystems; however, they are increasingly threatened by rising sea levels and a decline in fluvial sediment supply. The survival of a tidal marsh under these twin threats depends upon the net input of tidal sediments, because this will determine the deposition rate. The rate of relative sea level rise currently affecting the Yangtze Delta is rapid (~4 mm/a), and the sediment discharge from the Yangtze River has decreased by &gt;70% over recent decades. In order to improve our understanding of the response of the marshes in the turbid zone of the Yangtze Estuary to these changing environmental conditions, we measured sediment transport in and out of a tidal basin and calculated the deposition rate over eight tidal cycles covering different tidal ranges during the summer and winter seasons. The suspended sediment concentration (SSC) during the flood phase of the tidal cycle (average = 0.395 kg/m3) was markedly higher than that during the ebb (average = 0.164 kg/m3), although water transport during the flood tide was almost equivalent to that during the ebb. As a result, ~40% of the sediment inflow during the flood phase was retained within the marsh. This reason is mainly attributable to the dense marsh vegetation, which attenuates waves and currents and to which the sediments adhere. The annual deposition rate in the marsh was approximately 6.7 mm/a. These findings indicate that under the combined influence of sea level rise and river sediment supply reduction, the sediment transport through the turbidity maximum zone of the Yangtze River estuary could maintain the relative stability of the marsh area to a certain extent.

Impact of Floods on Sediment Trap Efficiency of a Small Shallow Reservoir—A Case Study

Silting is the main factor limiting the ability to perform the tasks that small reservoirs are intended for. Therefore, the change in sediment trap efficiency was studied for a small shallow reservoir, Krempna, which, due to high silting intensity, was desilted twice (2005, 2018). Siltation measurements were performed in two periods (1987–2005, 2006–2018) after the reservoir was desludged. It was found that the sediments were composed of fine-fraction sediment; therefore, a series of measurements of suspended sediment transport were performed. These data allowed us to calculate the daily sediment transport flowing into and out of the reservoir and water-level measurements. Then, the sediment trap efficiency was calculated. The aim of this study was: (1) to determine the impact of flood flows on the sediment trap efficiency (STE) of a small shallow reservoir, (2) to determine changes in the value of the sediment trap efficiency of a small shallow reservoir in two different periods of its operation, and (3) to demonstrate whether it is possible to determine the value of the initial sediment trap efficiency and changes in the STE values during operation using empirical formulas. Finally, during flood flows, the amount of sediment retained in the studied reservoir was several times lower than during freshets with a much smaller flow. It is these small freshets that reduce the capacity of the reservoir. A correlation relationship was developed for 18 data—flood flows (Q) and sediment trap efficiency (STE).

On predicting of some consequences of planned dam construction in a pristine sand-gravel river large catchment: Rio San Pedro, Nayarit, Northwest Mexico

The pressure on water and energy resources is increasing globally, particularly in emerging countries. Some of them use their rivers for electric power generation, paying little or no attention to the hydromorphological changes generated in the rivers due to the infrastructure associated. One case is the St. Pedro River in the Northwest of Mexico (Rio San Pedro), where it is planned to build a hydroelectric dam. The importance is due to its flow discharges directly to a marsh system called Marismas Nacionales, considered a Biosphere Reserve that includes approximately 20% of all mangroves in Mexico. The alteration of its natural conditions is a critical issue for the ecosystem. There are many studies about the effects of dams on rivers after their construction, but only a few related to the river characterization before intervention within its channel. In this work, we highlight the relevance of the latter. We conducted extensive fieldwork, including morphological survey, sediment transport measurement, hydrodynamics, and bathymetry over 80 km of the river. We establish a baseline with the hydromorphological parameters in the river and run a numerical simulation with 2-D HEC-RAS 6.1 model to compare natural and controlled runoff. The goal of our study was to discuss possible scenarios and some consequences that could be generated with the dam construction—alterations in the lower basin— and suggest actions that can help to minimize the detrimental consequences. The novelty of our work is the scope of fieldwork, the wide range of the data, careful modeling based on detailed field data, and finally, the possible way one might use our results in the future to minimize the adverse consequences of dam construction. The methodology presented can be used as a guide to other dam projects worldwide, which face all these issues and need to redesign the dam and consider modern techniques to preserve the riverine conditions close to the more natural possible.

Remote Observations of Aeolian Saltation

AbstractField measurements of aeolian sediment transport during major storm events are challenging in coastal settings due to the common coincidence of high winds with elevated water levels that can cover beaches. This work demonstrates a new application of lidar to remotely measure properties of wind‐blown sand transport at high spatial resolution. A data set of spatially continuous saltation heights was remotely developed from rapid (7.1 Hz) lidar scanning along a two‐dimensional transect across a beach during wind speeds of between 3.1 and 15.8 m/s associated with the passing of Tropical Storm Isaias. Outputs from the lidar demonstrate the ability to remotely observe the threshold velocity for the initiation of motion for sand transport and show that the upper limit of the saltation layer rises with increasing wind speed.

Evaluation of hydropower projects in Balkan Rivers based on direct sediment transport measurements; challenges, limits and possible data interpretation – Case study Vjosa River/Albania

AbstractThe Vjosa River in Albania represents one of Europe's last free‐flowing wild rivers, comprising a mosaic of various habitats and forming a highly dynamic natural ecosystem for flora and fauna, that has largely disappeared from other European rivers outside of Russia. However, due to economic interests, this sensitive and heterogeneous river system is under pressure from potential future use in hydropower, threatening the good hydromorphological and ecological status of the river with reservoir flushing, hydropeaking, colmation, loss of habitats and loss of connectivity. Beside the ecological impacts, this study aims to point out the boundaries for technical and economic issues related to hydropower. Hence, for the first time, sediment transport in the Vjosa River was measured. The results indicate possible consequences of a disturbed sediment regime and loss of capacity caused by the sedimentation of reservoirs. Moreover, subsequent consequences, such as river bed incision downstream of dams as well as progressive coastal erosion, are discussed. By combining data from direct bedload and suspended sediment measurements with long‐term hydrological data, an attempt is made to describe the sediment characteristics of the Vjosa catchment and evaluate potential hydropower plants and resulting reservoir sedimentation using limited data. Based on the presented study, it is aimed to define sediment monitoring standards for requested environmental impact assessments and to highlight possible negative impacts of hydropower projects across the entire Balkan region.

Field Measurement and Modeling of Sediment Transport along a Sandy Pocket Beach, Central West Coast of India

Abstract Sandy beaches generally are influenced by various coastal dynamic processes and undergo constant changes. The present study is an attempt to understand the hydromorphodynamic characteristi...