bluuebunny/crossref_metadata_2025 huggingface dataset:
Attraction effect of different colored cards on thrips Frankliniella intonsa in cowpea greenhouses in China
Authors: Mao Liangang , Chang Yiming , Yang Fulai , Zhang Lan , Zhang Yanning , Jiang Hongyun
Published: September 2018

The flower thrips Frankliniella intonsa (Trybom) is one of the most economically important pests in cowpea greenhouses in China. Widespread pesticide resistance of thrips and the negative environmental effects limit the application of pesticides for thrips control. Two commercial cowpea greenhouse experiments were designed to determine the color preference of F. intonsa to colored cards, including white, pink, pale green, light yellow, powder blue, crimson, yellow green, deep sky blue, dark slate blue, dark orange, medium orchid, gold, and black. Clear pieces of plastic were used as the control cards. Additionally, the effects of placement height and orientation (cardinal direction) of the cards were also studied. Both greenhouse trials showed that white cards were significantly more attractive to F. intonsa than the other 13 card colors, followed by deep sky blue cards. White or deep sky blue cards placed low to the ground were found to be most attractive to F. intonsa. Orientation of the colored cards also affected the attractiveness to F. intonsa. The results indicate that white sticky cards were significantly more attractive to F. intonsa than blue cards and therefore can be recommended to monitor F. intonsa population densities and to control them in cowpea greenhouses as part of integrated pest management programs.
Inferring the phase response curve from observation of a continuously perturbed oscillator
Authors: Cestnik Rok , Rosenblum Michael
Published: September 2018

Phase response curves are important for analysis and modeling of oscillatory dynamics in various applications, particularly in neuroscience. Standard experimental technique for determining them requires isolation of the system and application of a specifically designed input. However, isolation is not always feasible and we are compelled to observe the system in its natural environment under free-running conditions. To that end we propose an approach relying only on passive observations of the system and its input. We illustrate it with simulation results of an oscillator driven by a stochastic force.
Serum IgG2 levels are specifically associated with whole-body insulin-mediated glucose disposal in non-diabetic offspring of type 2 diabetic individuals: a cross-sectional study
Authors: Fiorentino Teresa Vanessa , Succurro Elena , Arturi Franco , Giancotti Aida , Peronace Cinzia , Quirino Angela , Sesti Franz , Andreozzi Francesco , Hribal Marta Letizia , Perticone Francesco , Focà Alfredo , Sesti Giorgio
Published: September 2018

Preclinical studies suggested that IgG2c isotype may specifically impair skeletal muscle insulin sensitivity in mice. In this study we investigated the association between serum levels of the four IgG subclasses and insulin sensitivity in non-diabetic individuals. Total IgG, IgG1, IgG2, IgG3 and IgG4 levels were measured in 262 subjects. Whole-body insulin sensitivity was assessed by euglycemic hyperinsulinemic clamp. IgG2 levels were positively correlated with BMI, waist circumference, 2-h post-load glucose levels and complement C3. Serum IgG2, but not IgG1, IgG3 and IgG4 levels were negatively correlated with whole-body insulin sensitivity (r = −0.17; P = 0.003) and muscle insulin sensitivity index (r = −0.16; P = 0.03) after adjustment for age and gender. No significant correlation was found between IgG2 levels and hepatic insulin resistance assessed by HOMA-IR and liver IR index. In a multivariable regression analysis including variables known to affect insulin sensitivity such as age, gender, BMI, smoking, lipids, inflammatory markers, fasting and 2-h post-load glucose levels, IgG2 levels were independently associated with insulin-stimulated glucose disposal (β = −0.115, 95% CI: −0.541 to −0.024; P = 0.03). These data demonstrate the independent association between higher levels of IgG2 and decreased whole-body insulin sensitivity, thus confirming in humans the animal-based evidence indicating the pathogenic role of IgG2 in insulin resistance.
Effects of gamma radiation on the bioactivity of medicinal and aromatic plants: Mentha × piperita L., Thymus vulgaris L. and Aloysia citrodora Paláu as case studies
Authors: Pereira Eliana , Pimenta Andreia I. , Barros Lillian , Calhelha Ricardo C. , Antonio Amilcar L. , Cabo Verde Sandra , Ferreira Isabel C. F. R.
Published: September 2018

Cytotoxicity, virucidal and phenolic compounds presented differences among the irradiated samples, while antimicrobial activity was not affected.
Nanostructuring of Si substrates by a metal-assisted chemical etching and dewetting process
Authors: Stafiniak Andrzej , Prażmowska Joanna , Macherzyński Wojciech , Paszkiewicz Regina
Published: September 2018

In this work, we reported on the development of lithography-free technology for the fabrication of nanopatterned Si substrates.
Fabrication of a blood compatible composite membrane from chitosan nanoparticles, ethyl cellulose and bacterial cellulose sulfate
Authors: Li Zhiming , Ma Jiazhi , Li Rongguo , Yin Xueqiong , Dong Wenyuan , Pan Changjiang
Published: September 2018

A blood compatible membrane was fabricated through electrospinning a solution of chitosan nanoparticles and ethylcellulose onto a bacterial cellulose sulfate membrane to mimic heparin's structure.
Tunnable rectifying performance of in-plane metal–semiconductor junctions based on passivated zigzag phosphorene nanoribbons
Authors: Su ShaoLong , Gong Jian , Fan Zhi-Qiang
Published: September 2018

Using first principles density functional theory, we perform a systematic study of the band structures of passivated zigzag phosphorene nanoribbons (ZPNRs) and the transport properties of in-plane metal–semiconductor junctions.
A facile route to magnetic mesoporous core–shell structured silicas containing covalently bound cyclodextrins for the removal of the antibiotic doxycycline from water
Authors: Zhang Ying , Jiang Fuquan , Huang Danya , Hou Shushan , Wang Hongli , Wang Minggang , Chi Yue , Zhao Zhankui
Published: September 2018

The controllable synthesis of a core–shell structured mesoporous organic–inorganic hybrid nanocomposite, Fe3O4@SiO2@mSiO2-CD, which demonstrates good adsorption of doxycycline.
A green metal–organic framework to monitor water contaminants
Authors: Rocío-Bautista Priscilla , Pino Verónica , Ayala Juan H. , Ruiz-Pérez Catalina , Vallcorba Oriol , Afonso Ana M. , Pasán Jorge
Published: September 2018

A low cytotoxic MOF prepared with an environmental-friendly approach, as a novel extractant of water pollutants using a microextraction method.
A new sensitive UPLC-MS/MS method for the determination of cucurbitacin B in rat plasma: application to an absolute bioavailability study
Authors: Xiao Ya , Zhao Qiang , Wu Qian , Chang Jinhua , Xue Hefei , Liu Cuizhe , Liu Xigang
Published: September 2018

A method was developed for the determination of CuB in plasma using UPLC-MS/MS with estrone as an internal standard, and the pharmacokinetics and absolute bioavailability of CuB in rats were examined.
Nutrient value of fish manure waste on lactic acid fermentation by Lactobacillus pentosus
Authors: Shi Suan , Li Jing , Guan Wenjian , Blersch David
Published: September 2018

Fish manure wastes are an effective nutrient source for lactic acid production using simultaneous saccharification and fermentation.
Exploring organic photosensitizers based on hemicyanine derivatives: a sustainable approach for preparation of amide linkages
Authors: Deol Harnimarta , Kumar Manoj , Bhalla Vandana
Published: September 2018

Hemicyanine derivatives C1–C4 have been synthesized and utilized as photocatalysts in additive/base free oxidative amidation of aromatic aldehydes in mixed aqueous media under visible light irradiation at low catalytic loading.
Synthesis of novel genistein amino acid derivatives and investigation on their interactions with bovine serum albumin by spectroscopy and molecular docking
Authors: Long Xiaokang , Zeng Yao-Fu , Liu Yunmei , Liu Ying , Li Tangluo , Liao Lanqing , Guo Yu
Published: September 2018

Introducing amino acid into genistein can not only improve its antitumor activity, but also enhance its binding affinity to BSA.
Correction: Tracking intramolecular energy redistribution dynamics in aryl halides: the effect of halide mass
Authors: Liu Xiaosong , Song Yunfei , Zhang Wei , Zhu Gangbei , Lv Zhe , Liu Weilong , Yang Yanqiang
Published: September 2018

Correction for ‘Tracking intramolecular energy redistribution dynamics in aryl halides: the effect of halide mass’ by Xiaosong Liu et al., RSC Adv., 2018, 8, 29775–29780.
Circulating level of fibroblast growth factor 21 is independently associated with the risks of unstable angina pectoris
Authors: Cheng Jing , Su Xing , Qiao Lei , Zhai Chungang , Chen Wenqiang
Published: September 2018

There is increasing evidence that serum adipokine levels are associated with higher risks of cardiovascular diseases. As an important adipokine, fibroblast growth factor 21 (FGF21) has been demonstrated to be associated with atherosclerosis and coronary artery disease (CAD). However, circulating level of FGF21 in patients with angina pectoris has not yet been investigated. Circulating FGF21 level was examined in 197 patients with stable angina pectoris (SAP, n=66), unstable angina pectoris (UAP, n=76), and control subjects (n=55) along with clinical variables of cardiovascular risk factors. Serum FGF21 concentrations on admission were significantly increased more in patients with UAP than those with SAP (Ln-FGF21: 5.26 ± 0.87 compared with 4.85 ± 0.77, P<0.05) and control subjects (natural logarithm (Ln)-FGF21: 5.26 ± 0.87 compared with 4.54 ± 0.72, P<0.01). The correlation analysis revealed that serum FGF21 concentration was positively correlated with the levels of cardiac troponin I (cTnI) (r2  =  0.026, P=0.027) and creatine kinase-MB (CK-MB) (r2  =  0.023, P= 0.04). Furthermore, FGF21 level was identified as an independent factor associated with the risks of UAP (odds ratio (OR): 2.781; 95% CI: 1.476–5.239; P=0.002), after adjusting for gender, age, and body mass index (BMI). However, there were no correlations between serum FGF21 levels and the presence of SAP (OR: 1.248; 95% CI: 0.703–2.215; P=0.448). The present study indicates that FGF21 has a strong correlation and precise predictability for increased risks of UAP, that is independent of traditional risk factors of angina pectoris.
Robust integral sliding mode‐ control of one‐sided Lipschitz non‐linear systems
Authors: Saad Wajdi , Sellami Anis , Garcia Germain
Published: September 2018

This study is concerned with the problem of ‐integral sliding mode control (SMC) for one‐sided Lipschitz (OSL) non‐linear systems. Unmatched norm‐bounded uncertainties and disturbances are considered. The design procedure gathers the high robustness qualities of the SMC and the measure performance. Initially, the solvability condition for the integral sliding surface is established and new sufficient linear matrix inequality (LMI) condition is derived such that the sliding mode dynamics is robust exponentially stable and has a disturbance attenuation performance. Then, an appropriate SMC law is synthesised to force the states of the system towards the sliding surface in finite time and to maintain a sliding motion on it thereafter. At last, two simulation examples are provided to prove the feasibility of the proposed method.
Elaboration of spherical particles of PMMA/ZnO through macroporous polymer networks
Authors: Monreal Humberto , Zubia Carolina , Sagarnaga Diana , Perez Teresa , Martìnez Carlos , Chacon Jose
Published: September 2018

In this study, it is explained how spherical particles of poly(methyl methacrylate) (PMMA)/ZnO were synthesised in the presence of a polymer matrix of galactopyranose for their control growth. The objective of this research is to show the development of particles using the sol–gel method and the participation of a polysaccharide network. This method can increase the formation of stable spherical particles due to the hydrogen bonds junctions present in the walls of the polysaccharide network. The results of the formed tablets immersed in simulated body fluid indicate that there is no evidence of corrosion in the presence of PMMA/ZnO nanoparticles. The maximum roughness average (Rmax) and roughness value (Ra) were 0.41 and 1.27 nm, respectively. The absorbance values showed significant changes when 10% polysaccharide concentration was used both in the presence and absence of the PMMA/ZnO nanoparticles. The particles were characterised by scanning electron microscopy, atomic force microscopy, powder X‐ray diffraction (PXRD), X‐ray elemental mapping, ultraviolet–visible spectrophotometry, and energy dispersive X‐ray spectroscopy. The PXRD analysis shows the crystalline and amorphous phases of the composite at 400°C. The size range of the synthesised particles was between 30 and 100 µm.
Hazards due to large wood accumulations: Local scour and backwater rise
Authors: Schalko Isabella , Schmocker Lukas , Weitbrecht Volker , Boes Robert M.
Published: September 2018

Large wood (LW) in rivers increases the flow variability and provides habitats for various species. During flood events, transported logs can accumulate at river infrastructures and increase the flood hazard. LW accumulations result in an upstream backwater rise and may increase local scour, for instance at bridge piers. Consequently, estimates of the resulting backwater rise and local scour are necessary to improve the flood hazard assessment. This study presents the findings of flume experiments with a movable bed on local scour and backwater rise due to LW accumulations. The approach flow conditions and the bed material were varied systematically for a specific LW accumulation volume. For all experiments, the initial condition for the bed material was defined as weak transport, since the bed shear stress was slightly below the critical bed shear stress for incipient motion. The inflow Froude number was identified as the governing parameter for backwater rise due to LW accumulations. The present study confirms the hypothesis that the resulting local scour reduces backwater rise. For the local scour, the unit discharge and the grain size diameter are the decisive parameters.
Calibration procedure of hydraulic simulations for the microhabitat method
Authors: Cassan Ludovic , Roux Hélène , Courret Dominique , Richard Sylvain
Published: September 2018

Hydropower plants can profoundly modify the natural morphology and hydrology of rivers and can alter the functionality of habitats for fish living and reproduction. In particular, hydropeaking leads to rapid and frequent changes of the hydrodynamic conditions and it is crucial to ensure aquatic habitat quality is maintained as much as possible during these periods. One present method to determine mitigation measure (minimum and maximum flow, rate of change) is to perform hydraulic simulations in 1D or 2D in the range of flow variation and to evaluate habitat quality for fish with the microhabitat method. The hydraulic model calibration has to be conducted carefully since the model has to reproduce precisely the hydraulic conditions from low to high flow rates (up to several times the mean flow of the rivers). Within this range, the friction coefficient can evolve greatly because at low flows the size of roughness elements become comparable to the water depth.. This phenomenon is observed by performing the modelling and the calibration at 2 stations on a river in French Pyrenees with different cross section shapes, one with progressive overflowing of some banks with large blocks and the other one without such phenomena. Thanks to field measurements of water levels at low and high discharge, the calibration process has shown that the friction coefficient can be multiplied by 2 as a function of the discharge. The paper proposes a methodology to evaluate the most appropriate tool. As water depth is concerned, the 2D simulations (TELEMAC 2D) provide similar results to those obtained with 1D (HEC-RAS) because flow remains unidirectional. Then a sensitivity analysis is carried out to estimate the uncertainty on the fish habitat outputs for a fish species (brown trout in the present study) resulting from several widely used friction laws. These friction laws can lead to different conclusions about habitat suitability depending on the calibrated coefficient. Finally, to perform relevant habitat modelling, it is necessary to measure water levels at several discharges and to describe accurately the spatial variability of roughness height.
Self-Adjustment Process of Flow Pathway in a Narrow Curved Channel
Authors: Hayakawa Hiroshi , Kitao Tomonori , Sato Nobuo
Published: September 2018

This study focuses on river bed fluctuation of the curved channel with channel width narrowing, where is located in the inlet of the old meandering river with 30 (m) width from straightened one with 80 (m) in the Kushiro Wetland. From field survey, in response to change in water and sediment discharges, significant streamwise variation in water flow width in the curved channel adjusts in order to establish the dynamic equilibrium. Along the outer bank of curved channel, the secular bed deposit beside the outer bank is increasing, and as a result, the main streamline flows into the old river along the inner bank as left bank. Moreover, this narrowing curved channel easily leads to overspill some flood water including rich suspended sediment and to deposit some fine sand near channel side flood plain. We intend to explain above significant bed variations by using movable bed experiments with the distorted model. As a result, we suggest, though qualitatively, that the existence of the sandbar upstream of the curved channel causes the autonomous specification of the flow path width in the curved channel with a narrowing width, and that this flow path is formed.
Limiting the development of riparian vegetation in the Isère River: A physical modelling study
Authors: Claude Nicolas , Leroux Clément , Duclercq Marion , Tassi Pablo , El Kadi Abderrezzak Kamal
Published: September 2018

Physical modelling experiments are conducted to investigate if a modification of the Isère River (French Alps) hydrology by changing dams management is able to foster riverbed morphodynamic and, thus limiting riparian plant development. The experimental setup is a 1:35 scale, undistorted movable bed designed to ensure the Froude number similarity and initial conditions for sediment particle motion. The physical model is 35 m long, 2.6 m wide, with a sand mixture composed of three grain size classes. Two runs with different flow and bed load conditions are simulated. Preliminary results show an intense riverbed activity when the system reaches a dynamic equilibrium state. Under these conditions, bar mobility is strong enough to limit vegetation encroachment only when water discharges are higher than the discharge of a 5-years flood during more than 10 days. These results indicate that the hydrological characteristics of the Isère River and the actual configuration of the hydropower structures could be not able to release annually the flow conditions needed to control riparian plant development.
Predicting floodplain inundation and vegetation dynamics in arid wetlands
Authors: Sandi Steven G. , Saco Patricia M. , Kuczera George , Wen Li , Saintilan Neil , Rodriguez Jose F.
Published: September 2018

The Macquarie Marshes is a freshwater wetland system located in semiarid Australia. The ecological importance of this site has been recognized under the Ramsar convention. Plant associations in the marshes has shown a complex dynamic where some wetland vegetation patches have transitioned to terrestrial vegetation during severe drought, but also quickly responded to increased inflows due to record and near record rainfall accompanied by water releases from an upstream reservoir. Management decisions regarding the environmental flows require the use of predictive tools in order to assess the response of the vegetation. We have developed a vegetation response model that couples hydrodynamic modelling of the northern Macquarie Marshes with watering requirements of different plant associations and vegetation succession rules. The model simulates floods in the wetland during a series of years, after which patches of vegetation are analysed according to water depth, percent exceedance time and frequencies of inundation. During the simulated period, the patch can have adequate watering conditions, or it can have critical conditions that would lead to a succession to another type of vegetation. The predicted vegetation is reintroduced in the model, providing feedbacks for the next simulation period. In this contribution, we implemented the model to simulate changes of wetland understory during the period 1991 to 2014.
Hydraulics of braided river dynamics. Insights from flume experiments
Authors: Vesipa Riccardo , Camporeale Carlo , Ridolfi Luca
Published: September 2018

We focus on the measurement of the topography and bathymetry in flume-models of braided rivers. To this aim, an innovative measurement system is adopted. It consists of a laser-ultrasonic sensor and can survey the bed elevation under flowing water. This measurement system was used to profile a flume transect with a frequency of 2 minutes, without stopping the water discharge. By this technique, the topography and the bathymetry of a single transect was continuously acquired in 3 braided rivers generated with the same experimental set-up. The main results are: (i) the quantification of the variability of the number of channels and number of active channels; (ii) the assessment of the probability distribution of some key hydraulic and morphodynamic parameters; and (iii) the verification of the repeatability of results obtained from flume-models of braided rivers.
On the morphological evolution of restored banks: Case study of the Meuse river
Authors: Duró Gonzalo , Crosato Alessandra , Kleinhans Maarten , Uijttewaal Wim
Published: September 2018

In recent years, many riverbanks in Europe had their protections removed to reactivate natural erosion processes and improve riparian habitats. Yet, other river functions may be affected, such as navigation and flood conveyance. The quantification and prediction of erosion rates and volumes is then relevant to manage and control the integrity of all river functions. This work studies the morphological evolution of riverbanks along two restored reaches of the Meuse River in the Netherlands, which are taken as case studies. This river is an important navigation route and for this its water level is strongly regulated with weirs. Through aerial photographs and two airborne LIDAR surveys, we analysed the evolution over nine years of restoration and reconstructed the topography along 2.2 km. of banks. An extraordinary low-water level after a ship accident provided the opportunity to observe and measure the bank toe. The banks show a terrace of erosion close to the normally regulated water level, highly irregular erosion rates up to 7 m/year, embayments evolving with upstream and downstream shifts, and sub-reaches with uniform erosion. Probable causes of erosion include ship-waves, high water flows and water level fluctuations. Distinct patterns might be explained by the presence of riparian trees and soil strata of different compositions. These intriguing case studies will continue to be studied to disentangle the role of different erosion drivers, predict erosion magnitudes and establish whether bank erosion will stop or continue in the future.
River improvement techniques for mitigating river bed degradation and channel width reduction in the sandy Hii River where sediment transport occurs at normal times
Authors: Gotoh Takahisa , Fukuoka Shoji
Published: September 2018

In the sandy Hii River, a large amount of sediment yield from upper river basin had brought developments of braided channels covered with sand waves. In the braided channels, sediment materials on the river beds are capable to move in normal discharge conditions. In recent years, however, the sediment yield decreases due to constructions of check dams and ground sills in the upper river basin. Thus, the river beds downstream of the ground sill have gradually degraded and the main channel widths have been narrowed with the progressing bed degradation. Firstly, we clarified that the effects of non-equilibrium sediment transports around the ground sill during normal discharge conditions on the bed degradation and the channel width reduction by using annual observed data and numerical simulations for bed variations. In addition, we provided the river improvement techniques for mitigating bed degradation and channel width reduction by improving state of non-equilibrium sediment transports passing through the ground sill.
LES modelling of a flow within an infinite array of randomly placed cylinders: Anisotropy characterization
Authors: Ricardo Ana M. , Grigoriadis Dimokratis G.E. , Ferreira Rui M.L.
Published: September 2018

The LES approach is employed to model flows within random arrays of emergent cylinders. The model is validated against laboratory data acquired with a 2D-2C Particle Image Velocimetry system. The main goals are: i) discussion of the effect of the numerical domain size and the grid resolution on the predicted flow variables; and ii) spatial characterization of the flow anisotropy. Three domains of different sizes (16 to 36 cylinders) and four grid resolutions were independently tested. A 2D methodology was proposed to characterize the flow anisotropy on the horizontal plane. The results show that the first and second order moments were not significantly affected by the size of the tested numerical domains or by the grid resolution. The comparison with laboratory data showed a fair agreement confirming that the numerical model was able to adequately reproduce all the components of the Reynolds stress tensor. The results show that turbulence is of axisymmetric expansion nature in this type of flow. Relatively to the degree of anisotropy, the highest values were found close to the cylinder, decreasing gradually downstream towards the isotropy state. However, a truly isotropic turbulence state is not reached.
Shallow flow over a bed with a lateral change of roughness
Authors: Dupuis Victor , Moulin Frédéric , Cazin Sébastien , Marchal Moïse , Elyakime Pierre , Barron Jean-Dominique , Eiff Olivier
Published: September 2018

River beds frequently exhibit a lateral variation of roughness. For example, in the case of an overflowing river, the main channel has a smoother topography compared to the adjacent floodplains where vegetation and land occupation yield an important hydraulic roughness. The lateral difference in roughness can induce a high lateral velocity gradient within the river cross- section that gives birth to a mixing layer. This mixing layer leads to fluid and momentum transfers between the two adjacent beds. To understand such mix- ing processes in rivers is important for predicting stage-discharge relationships and the velocity distribution within the cross-section. In order to address these issues in the context of a shallow water flow with a water depth h of the same order as the roughness elements of the bed, experiments were undertaken in a 26 m long and 1.1 m wide glass-walled open-channel flume. One half-side of the bed was covered with an array of cubes of height k arranged in a square configuration, the other side with smooth glass. Three different levels of cube submergence h/k were examined (h/k = 0.8, 1.5 and 2). The experiments and measurements were designed to yield the flow in the complete volume of the interstices across the cube array. To achieve this, 2C-3D linear-scanning PIV measurements with zero-parallax optics were developed and set up. The mea- surements revealed the complexity of the flow structure around the interface between the rough and smooth beds. The results show that the ability of the mixing layer to exchange momentum is highly dependent on the level of the cube submergence h/k.
Drag and Reynolds stress distribution within submerged vegetation canopies
Authors: Nikora Nina , Nikora Vladimir
Published: September 2018

In the last few decades extensive studies focusing on both qualitative and quantitative descriptions of the Reynolds stress within aquatic canopies have been carried out. Although these studies have advanced our knowledge of mechanics of flow-vegetation interactions, further research in this area is still required. In particular, there is a need for development of new simple physically-based relationships describing the Reynolds stress profiles within submerged vegetation canopies. This paper addresses this issue and proposes a physically justified formulation for the Reynolds stress profile within the canopy region.
Dynamic characterization of meandering channels planform
Authors: Dominguez Lucas , Gutierrez Ronald , Ponte Yoch , Abad Jorge D. , Carrera Oscar
Published: September 2018

Meandering channels develop different geometry patterns along the floodplain during its evolution. These natural processes lead to developing lateral and longitudinal migration, describing a sort of swept that affect the human activities. As the equilibrium geometry of natural channels depends on: the flow and sediment discharge, geological conditions of valley, soil properties, and vegetation among others, the preliminary characterization is not easy. Due to this, several engineering and scientific problems require an appropriate description of morphological processes. The dynamic characterization like the quantification of wavelength, amplitude, sinuosity, and curvature using Medium Temporal Scheme (MTS) is using widely. Unlike the traditional scheme that only uses short or long-term schemes, MTS includes relevant morphological events (e.g., cutoff). In addition this, the satellite images has increased and achieves a high spatial resolution, even more when studying large basins. This paper presents and validates a MATLAB®-based toolbox called Meander Statistics Toolbox (MStaT) to perform the dynamic characterization of several meandering channels using the MTS. To run MStaT only need the centerline (CL), and the average width of channel as input parameters. To maximize the toolbox, MStaT incorporates the Wavelet Analysis (WA) to decompose the signal (CL) and obtains the power spectrum. Finally, two studies cases (synthetic and natural channels) will be presented to validate MStaT.
Reservoir sedimentation impact downstream in a semi-arid basin with greenhouses cultivation
Authors: Arjona Sergio , Millares Agustín , Baquerizo Asunción
Published: September 2018

This work analyzes the loss of storage, in a medium-term basis, of Beninar reservoir (Almería, Spain) built in a semiarid watershed and its consequences downstream. The reservoir, in the Adra river basin (Southern Spain), was designed to supply water for the irrigation of more than 28.000 hectares of greenhouses. Its storage volume, that was initially of 68 hm3 in 1984, has been reduced approximately to half. The total sediment volume arrived to the reservoir during the last 32 years is 6,8 hm3, of which 1,68 hm3 are estimated to come from fluvial contributions. The results remark the torrential nature of rainfall events for generating large sediment contributions and highlights the importance of taking into account these types of events. The total loss of storage is especially relevant from two points of view 1) reduction of flood abatement due to sedimentation and structural problems of dam, which has left only 2 hm3 of regulation capacity and 2) loss of water volume which is essential to improve the water quality of the overexploited and salinized aquifers which supply the greenhouses downstream. Beninar reservoir is a key infrastructure to preserve a competitive price of water for greenhouse cultivation.
THREE DIMENSIONAL FLOW STRUCTURES AROUND A DEEP SCOUR HOLE
Authors: Tominaga Akihiro , Sassa Naohiko , Hara Yuji , Kuno Yuka
Published: September 2018

The existence of a planform vortex is considered to be the cause of development and sustention of large-scale local scouring in the Kiso River. In order to make clear the 3D flow structures in this deep local scour, we conducted a field observation and model experiments. From the result of ADCP set on the bottom of the scour hole, the velocity in the hole was increasing and the vertical vortex was developing, with an increase of river discharge. It is indicated that considerable magnitude of velocity was generated even near the bottom by the action of vertical vortex. This vortex was recognized in the model experiments. Consequently, the vertical vortex contributes to develop and maintain the large-scale local scouring.
Factors influencing the sediment delivery ratio of the Three Gorges Reservoir
Authors: Wang Dayu , Hu Chunhong , Fang Chunming , Guan Jianzhao , Zhang Lei
Published: September 2018

In recent years, the sediment delivery ratio (SDR) of the Three Gorges reservoir (TGR) has noticeably decreased as a result of the increase in water levels at the dam site and the decrease in inflow of fine particles, thereby resulting in increased reservoir siltation. Therefore, it is vital to research the factors that influence the SDR of the TGR. Factors that could have impact on the SDR were studied using TGR monitoring data. The study indicated that the water level at the dam site and inflow and outflow rates could have contributed to the change in the SDR. A sensitivity analysis of the influencing factors was then carried out using a mathematical model to simulate numerous sediment movement scenarios in the TGR. By changing the input conditions of the model, sufficient results were obtained to enable a sensitivity analysis of each factor. The results showed the flood retention time (FRT)—the ratio of reservoir capacity to average outflow discharge—was the principal factor influencing the SDR. The other factors (inflow sediment concentration, inflow sediment coefficient, inflow sediment gradations, and the shape coefficient of the inflow flood shape coefficient), also had an influence on the SDR. However, under different levels of FRT, their degrees of influence on the SDR were not the same..
Fish swimming kinematics in a turbulent wake: To spill or not to spill?
Authors: Muhawenimana Valentine , Wilson Catherine A. M. E. , Cable Jo
Published: September 2018

Due to the complex nature of fish-environment interactions, the effects of altered flow conditions on fish habitats and behaviour, particularly near obstructions, are not yet fully understood. Many hydro-engineering structures generate three-dimensional turbulent structures that differ in properties from naturally occurring ones, and are challenging to fish movement. Here, swimming stability and habitat usage of Nile tilapia (Oreochromis niloticus) were examined in the turbulent wake of a horizontally oriented cylinder (50 mm diameter, D) for a series of increasing cylinder Reynolds numbers (Red). Velocity statistics showed that the near wake downstream of the cylinder within a 2D distance had higher magnitudes of longitudinal, vertical and lateral velocity components as well as Reynolds stresses, turbulence intensity and turbulent kinetic energy than the remaining wake flow field. Flow accelerating over the cylinder top and underside generated two shear horizontal layers, where two coherent structures were formed due to the shear layer breakdown off the cylinder’s walls and alternating von Karman-type vortex shedding occurred in the wake of the cylinder. The eddy symmetry and vorticity off the cylinder’s edges was dependent on Red. The recorded total number of spills, defined as loss of balance, was inversely proportional to fish length and weight, and depended on proximity to the cylinder and the flume bed. Furthermore, the frequency of spills was closely linked to the orientation of vortices and magnitude of Reynolds stresses, suggesting that these parameters may govern the swimming stability of fishes. This information may be used to inform the design of fish-friendly obstacles including hydraulic structures and hydro turbines in riverine and estuarine systems.
Degradational response of engineered channels to changes in the upstream controls and channel width: Simplified 1D numerical simulations
Authors: Siele Meles , Blom Astrid , Viparelli Enrica
Published: September 2018

In response to changes in the upstream controls (i.e., the water discharge, the sediment supply rate, and the calibre of the load), engineered alluvial channels adjust their bed slope and bed surface texture to establish a new equilibrium state. Here we present and discuss various causes of degradational response of engineered channels to changes in the upstream controls and channel width. For that purpose, we apply a simplified 1D numerical research code to a schematic river reach of constant width consisting of mixed-size sediment, and assess its equilibrium state and transient response. We illustrate that the following perturbation to an initially equilibrium state lead to a degradational response: an increase of the water discharge, a decrease of the sediment supply rate, an increase of the sand content of the sediment supply, an increase of the gravel content of the sediment supply, and a decrease of the channel width. Degradational response under all conditions is associated with surface coarsening. The equilibrium states of the numerical simulations agree with analytical solutions. The results provide insight into the current degradational response of engineered rivers, such as the Rhine River, the Elbe River and the Danube River.
Grain and bedform roughness properties isolated from gravel-patch DEMs
Authors: Bertin Stephane , Groom Jane , Friedrich Heide
Published: September 2018

Remote sensing of gravel-bed patches and resulting high-resolution digital elevation models (DEMs) allow for the identification of various spatial scales of surface roughness. Thus far, dimensions relating to grain and bedform roughness scales have been determined using semivariograms or equivalent structure/autocorrelation functions. However, it is difficult to clearly differentiate roughness scales and separate analysis of roughness properties is not possible. This study examines the use of moving-window detrending on gravel-patch DEMs for isolating grain and bedform roughness and their respective topographic signatures. An extensive dataset of water-worked gravel surfaces collected in both laboratory and field environments is used. The measured bed topography is separated into two distinct DEMs: one representing grains, the other representing bedforms, and roughness properties are determined separately for grain and bedform DEMs. The results show that both roughness scales are controlled by the size of the coarse sediment forming the bed surface, with positive linear relationships connecting bed composition and vertical roughness. Coarse sediment is controlling bedform development by forming humps on the surface, in the lee of which finer sediment is sheltered. We present synthesis relationships connecting vertical roughness of gravel patches to the vertical roughness of grains and bedforms.
Suspended sediment dynamics by event typology and its siltation effects in a semi-arid snowmelt-driven basin
Authors: Millares Agustín , Moñino Antonio , Arjona Sergio , Baquerizo Asunción
Published: September 2018

Soil loss and transport processes are key issues to understand erosive and sedimentary dynamics in semi-arid environments. The aim of this work was to characterize the erosive patterns of different types of events and to analyse their effect downstream in a mountainous semi-arid watershed. With that purpose, different events have been typified according to atmospheric and hydrological descriptors from information of 1)historical meteorological data, 2) results of simulations from physically-based and distributed hydrological modeling, which includes the snowmelt dynamics, and 3) available MODIS satellite images. For each event, water samples were taken by an automatic measuring device and analysed to determine the suspended sediment loads. The results allowed to identify three types of events. Among them, the maximum values of the measured suspended solids during rainfall-dominated events, with little snow influence, were an order of magnitude higher than the snowfall-dominated events, with values of 25000 mg/l versus 2500 mg/l respectively. The response of intermediate events, despite of low flow, showed a significant gradient. The results highlight the great dynamic variability of the sediment yield along the basin and the importance of the snow in the lamination of the erosive processes and their consequences on reservoir siltation.
Vertical grain size sorting in bedload transport on steep slopes with a coupled fluid-discrete element model
Authors: Frey Philippe , Chassagne Rémi , Maurin Raphaël , Chauchat Julien
Published: September 2018

In order to study vertical grain size sorting in bedload sediment transport, numerical experiments of two-size particle mixtures were carried out, using a validated coupled fluid-discrete element model developed at Irstea. A 3D 10% steep domain, consisting at initial time of a given number of layers of 4 mm particles deposited on top of a coarser 6 mm particle bed, was sheared by a turbulent and supercritical fluid flow (Shields numbers of 0.1 and 0.3). The elevation of the centre of mass of the infiltrated fine particles is observed to follow the same logarithmic decrease with time, whatever the initial number of fine layers. This decrease is steeper for a higher Shields number. The main result is that this typical behaviour is related at first order to the particle shear rate depth profile.
A gravity-driven runoff and erosion model for sediment transfers at the catchment scale
Authors: Taccone Florent , Antoine Germain , Delestre Olivier , Goutal Nicole
Published: September 2018

The aim of this work is to simulate hydraulic transfers and upstream erosion sources in steep and erodible mountain watersheds with a physicallybased hydraulic model. In such environments, immature debris flows and shallow landslides can be the largest sources of sediments transported at the outlet. To simulate these phenomena, a gravity-driven erosion model and a 1D vertical infiltration model have been developed in the TELEMAC 2D numerical code. In this new erosion model, the motion of the granular flow is described with a fully dynamic system and a Coulomb-like bottom friction treatment, more adapted to the properties of the flow. The new model is first qualitatively evaluated on a theoretical test case: a steep plot with a slope break is used to evaluate the erosion and deposition dynamics of a single immature debris flow. Then, the model is confronted to field data on a real catchment (Draix, in the Southern French Alps). First, the infiltration model is successfully calibrated in order to simulate two different rain events. Then, the new erosion model is applied at the catchment scale. The numerical results show a very realistic behavior compared to the field observation, providing erosion in the upper parts of the hillslopes and deposition in the hydraulic network. This work opens promising perspectives, for example by coupling this new model with a classical and complementary velocity-driven model for the erosion, deposition and transfers in the hydraulic network.
Questions in the quantitative analysis of sediment load - example of three major rivers in Hungary
Authors: Tamás Enikő Anna , Ficsor Johanna
Published: September 2018

The importance of the monitoring of sediment processes is unquestionable: sediment balance of regulated rivers suffered substantial alterations in the past century, affecting navigation, energy production, fish habitats and ecosystems alike. The changes in flood characteristics and rating curves of our rivers are being researched and described, involving state-of-the-art measurement methods, modeling tools and traditional statistics. Sediment processes however, are much less known. Sediment-related research is scarce, which is partly due to the outdated methodology and poor database background in the specific field. Regular sediment sampling was developed in the first half of the 20th century, with different station density and monitoring frequencies in different countries. Sampling frequency of suspended load is 3 to 7 per year in Hungary, and even lower for the bed-load, not only on the Danube river but also on large tributaries like the Drava and the Tisza rivers. Data related to sediment quantity are unreliable and often contradictory. It is difficult to produce high quality long-term databases that could enable the calibration of sediment transport models. It is a challenge to compare measurements on international rivers. The authors give an overview of sediment sampling methods, an inventory of the available datasets and data management in Hungary on the rivers Danube, Drava and Tisza, based on field data.
Predicting the vortex shedding frequency at the interface of the lateral cavities
Authors: Perrot-Minot Clément , Mignot Emmanuel , Riviere Nicolas , Perkins Richard
Published: September 2018

The vortex shedding frequency in the mixing layer between a cavity and a main stream has been examined experimentally in absence of large oscillation of the free surface inside the cavity, called seiching. It was observed that the vortex shedding frequency follows a monotonically increasing trends with possible jumps from one to another with increasing Froude number of the main stream. These trends are obtained by solving a model based on the Rossiter approach. This model considers that the vortices shed in the mixing layer create some water depth variation at the impingement corner of the cavity. This water depth variation in turn generate pressure waves that propagates upstream and influence the vortex shedding process. Finally the measured vortex shedding frequencies correspond quite accurately to the frequencies predicted by the model. This highlights the existence of a resonant phenomena between vortices in the mixing layer of a lateral cavity and gravity waves even without any seiching phenomena.
Large-eddy simulation study of turbulent flow around a rectangular spur dike
Authors: Kang Seokkoo
Published: September 2018

High-resolution large-eddy simulation (LES) is carried out for investigating three-dimensional flow fields around a rectangular spur dike installed in an open-channel flume. The LES showed good agreement with the measurement obtained using Acoustic Doppler Velocimetry. Analysis of the LES result shows that the flow structure around and in the wake of the spur dike is highly complex and three-dimensional. Namely, flow upstream of the spur dike is featured by a vortex system near the bed, another vortex system beneath the free surface, and a recirculation region in front of the spur dike. All of these flow structures are laterally oriented. Moreover, flow in the wake region consists of a large vertically oriented recirculation region and a smaller laterally oriented recirculation region near the bottom corner downstream of the spur dike.
Application of a Eulerian two-phase flow model to scour processes
Authors: Mathieu Antoine , Nagel Tim , Bonamy Cyrille , Chauchat Julien , Cheng Zhen , Liu Xiaofeng , Hsu Tian-Jian
Published: September 2018

In this paper, the application of a two-phase flow model to scour processes is presented. The model is first calibrated against experimental data of unidirectional sheet-flow (one-dimensional configuration). The model is then applied to multi-dimensional configurations for the scour under a submarine pipeline and around a vertical pile. The results show that quantitative results can be obtained at the upstream sides of structures, the lee-wake erosion driven by the vortex shedding deserves further research.