Article
Environmental Sciences
Marwan A. Hassan, Wenqi Li, Enrica Viparelli, Chenge An, Alexander J. Mitchell
Summary: Channel stability and sediment transport in gravel bed streams are influenced by fluid forces, bed surface structures, armoring, and sediment supply/storage. This study focuses on the impact of sediment supply timing on bedload transport rate, grain size distribution, and channel morphology. Flume experiments were conducted with five different sediment feeding schemes. Results showed that sediment transport rates varied over five orders of magnitude regardless of the feeding scheme. Clockwise hysteresis was observed for bedload transport rate and grain size, indicating higher transport rate and coarser grain size during the rising limb. Counterclockwise hysteresis was observed for the grain size distribution of the bed surface, suggesting that the bed surface was finest during the rising limb. Sediment yield during the rising limb was higher than during the falling limb, indicating the importance of sediment supply timing in sediment transport. This study provides valuable insights for sediment supply projects in restoring gravel bed streams.
WATER RESOURCES RESEARCH
(2023)
Article
Geosciences, Multidisciplinary
Elizabeth H. Dingle, Kyle M. Kusack, Jeremy G. Venditti
Summary: Gravel-sand transitions in river channels result in a significant reduction in median grain sizes, typically occurring a short distance downstream of mountain ranges or at a characteristic backwater distance upstream of a base-level control. While universal morphological characteristics associated with the transition are lacking, backwater effects and exhaustion of gravel supply can generate a distinct change in water surface slope.
EARTH-SCIENCE REVIEWS
(2021)
Article
Geosciences, Multidisciplinary
Daniel C. White, Peter A. Nelson
Summary: Meandering gravel-bed rivers exhibit sorting patterns with fine particles on bar tops and coarse particles in pools. The mechanism behind these patterns is poorly understood for gravel-bed meandering channels.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2023)
Article
Environmental Sciences
Chenge An, Zheng Gong, Kensuke Naito, Gary Parker, Marwan A. Hassan, Hongbo Ma, Xudong Fu
Summary: Many sand-bed rivers worldwide are experiencing reductions in sediment load, leading to river delta drowning. This study proposes a grain size-specific relation to simulate river morphodynamic evolution, finding that sediment grain sorting accelerates bed surface armoring and reduces sediment load delivery to the delta. These results have practical implications for river delta restoration.
WATER RESOURCES RESEARCH
(2021)
Article
Engineering, Marine
Tristan B. Guest, Alex E. Hay
Summary: This study utilized aeroacoustic and optical remote sensing techniques to observe the morpho-sedimentary dynamics in the swash zone of a mixed sand-gravel beach. The data showed a correlation between increases in bed level and mean grain size, as well as finer-scale structures and the migration of coarse-grained material. Close-range remote sensing techniques provided valuable insights into the dynamics of cobble-sized and sand-sized particles in the swash zone.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2021)
Article
Engineering, Civil
Saman Solati, Mohammad Vaghefi, Abdol Mahdi Behroozi
Summary: This study investigated the effects of peak occurrence time and flood duration on scour around bridge piers in sharply bended channels. Results showed that different peak occurrence times and durations had varying impacts on maximum scour depth and sediment progression around the bridge piers.
INTERNATIONAL JOURNAL OF CIVIL ENGINEERING
(2021)
Article
Geography, Physical
Brett C. Eaton, Lucy G. MacKenzie, Caitlin Tatham
Summary: This paper introduces a novel approach called geomorphic river engineering to limit stream channel instability. The approach relies on the stabilizing effects of coarse sediment and modulates the rate of bank erosion during flood events. The results suggest that depositing a moderate volume of coarse sediment on a gravel bed stream can significantly reduce lateral migration, and the degree of stabilization can be adjusted by changing the amount of sediment placed on the floodplain.
EARTH SURFACE PROCESSES AND LANDFORMS
(2022)
Article
Geography, Physical
Jules Le Guern, Stephane Rodrigues, Thomas Geay, Sebastien Zanker, Alexandre Hauet, Pablo Tassi, Nicolas Claude, Philippe Juge, Antoine Duperray, Louis Vervynck
Summary: This study evaluated various bedload measurement techniques and found that hydrophone measurement is the most effective and accurate method in a large sandy-gravel-bed river. Further research is needed to determine the parameters controlling self-generated sediment noise, and the calibration procedure used in this study provides a satisfactory estimation of bedload transport rates. Additionally, aDcp and hydrophone measurement techniques are accurate enough to quantify bedload variations associated with dune migration.
EARTH SURFACE DYNAMICS
(2021)
Article
Environmental Sciences
Chenge An, Xudong Fu
Summary: This study evaluates the applicability and limitations of the rate law model in simulating river morphodynamic processes. The results show that the rate law model can predict the adjustment of bed elevations, but is incapable of describing the adjustment of bed surface texture.
INTERNATIONAL JOURNAL OF SEDIMENT RESEARCH
(2022)
Article
Environmental Sciences
Lina Pang, Yanxin Sun, Yao Yue, Caiqiong Liu, Chenge An, Tiantian Yang, Xinhua Lu, Quanxi Xu, Jie Mei, Min Liu, Xiaofeng Zhang
Summary: This study investigates the effects of dramatic hydrological changes on aquatic nitrogen cycle in the Three Gorges Reservoir. The results show that water flow homogenization and sediment reduction have little impact on ammonia nitrogen and total nitrogen concentrations, indicating relative stability of the microbial community. However, N-2 emissions vary greatly, with an increased emission range but decreased total emission. Microbial N-2 producing process shows quick response and strong adaptation to the environmental changes, which is beneficial for maintaining ecological functions related to nitrogen cycling.
Article
Mechanics
Weiquan Jiang, Li Zeng, Xudong Fu, Zi Wu
Summary: This article investigates the influence of reversible adsorption-desorption on solute dispersion and proposes a simpler analytical method to derive solutions using the Laplace transform. The classic framework of separation of variables is extended to explore higher-order statistics in practice, and Gill's generalized dispersion model for solute concentration distributions is also extended to address transient dispersion characteristics. The study analyzes the influence of reversible adsorption-desorption on solute cloud and discusses the characteristics of different concentration distributions.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Geosciences, Multidisciplinary
Yongpeng Lin, Chenge An, Gary Parker, Weiming Liu, Xudong Fu
Summary: This study examines the morphodynamics of bedrock-alluvial rivers and the impact of landslide dam outburst floods. The simulation results reveal that during flood events, bedrock is eroded. In the following decades or centuries, landslide deposits can cover the river channel, hindering bedrock downcutting and resulting in a net rise of the bedrock surface. Eventually, a bedrock bump moves upstream and beyond the river reach over tens of thousands of years. When repeated dam breach events occur at a single site, a dynamic balance is achieved, with steeply increased bedrock slope near the dam site and gently decreased slope downstream. The study demonstrates the significant influence of landslide dam outburst floods on the behavior of bedrock channels.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2022)
Article
Geosciences, Multidisciplinary
Shan Zheng, Hualin Wang, Chenge An
Summary: This study investigates the complex evolution of the upper North Fork Toutle River (NFTR) following the catastrophic eruption of Mount St. Helens in 1980. The study improves the alluvial phase space diagram (APSD) to classify channel adjustment and applies it to analyze the NFTR in the 1980s. The findings reveal a sequence of changes in channel morphology, including degradation, aggradation, and renewed incision, with the middle transitional reach acting as a hinge zone. The study emphasizes the importance of the time scale at which the APSD is applied for studying channel adjustment.
Article
Mathematics, Applied
Zheng Gong, Gefei Deng, Chenge An, Zi Wu, Xudong Fu
Summary: This study presents a high order finite difference solver for direct numerical simulations of turbidity currents. By optimizing parallel configurations and searching for the fastest solver scheme, the efficiency and performance of the simulations are improved. Benchmark simulations show good agreements with data obtained through spectral methods.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2022)
Article
Mechanics
Zi Wu, Weiquan Jiang, Li Zeng, Xudong Fu
Summary: This article investigates the statistical properties of bedload particle motions and provides analytical solutions for hop statistics. The deposition rate is found to be related to the mean travel times and hop distances of particles, allowing for a direct determination of the deposition rate based on measured particle motion statistics.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Computer Science, Interdisciplinary Applications
Zheng Gong, Zi Wu, Chenge An, Bangwen Zhang, Xudong Fu
Summary: We present CP3d, a comprehensive Euler-Lagrange solver for the direct numerical simulation of particle-laden flows, which can handle different coupling regimes and utilizes various numerical approaches for fluid, particle, and coupling sub-solver. The solver is validated against several benchmarks, and shows excellent computational accuracy and efficiency.
COMPUTER PHYSICS COMMUNICATIONS
(2023)
Article
Environmental Sciences
Guangmiao Li, Zheng Gong, Weiquan Jiang, Jie Zhan, Bohan Wang, Xudong Fu, Mengzhen Xu, Zi Wu
Summary: The transport of active particles in shear flows, such as microorganisms, plays a significant role in biological and environmental applications. The motility and gyrotaxis of algae have been shown to greatly influence their transport in waters. However, little attention has been paid to the initial and transient transport regime. In this study, we extend Gill's generalized dispersion model to active particles and thoroughly investigate the effects of swimming, gyrotaxis, and flow shear on microorganism dispersion in an open-channel flow. We find that the presence of flow enhances the transient drift velocity and dispersivity of microorganisms, while the absence of flow weakens the longitudinal dispersion due to gravitactic accumulation and stronger swimming ability.
WATER RESOURCES RESEARCH
(2023)
Article
Environmental Sciences
Yongpeng Lin, Chenge An, Shan Zheng, Ruihua Nie, Gary Parker, Marwan A. Hassan, Matthew J. Czapiga, Xudong Fu
Summary: Since the 2008 Wenchuan Earthquake, the Shi-ting River in China has experienced significant bed degradation. This degradation is a result of multiple factors, including the presence of in-channel weirs, earthquake-induced mobilization of sediment, and intensive sediment mining. The study shows that weirs can reduce bedload transport and cause bed degradation, especially when coupled with additional sand supply. The simulation and observation both indicate that sediment mining is likely the key factor contributing to the dramatic bed degradation in the Shi-ting River.
WATER RESOURCES RESEARCH
(2023)
Article
Multidisciplinary Sciences
Chenge An, Hongwei Fang, Li Zhang, Xinyue Su, Xudong Fu, He Qing Huang, Gary Parker, Marwan A. Hassan, Nooreen A. Meghani, Alison M. Anders, Guangqian Wang
Summary: This passage explains why two large lakes, Dongting Lake and Poyang Lake, exist along the Yangtze River. It suggests that rising sea levels due to deglaciation caused a wave of water surface elevation and bed aggradation. The blockage of tributaries by the main stem's aggradation resulted in the formation of the lakes.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Geography, Physical
Xingyu Chen, Marwan A. Hassan, Xudong Fu
Summary: Image-based grain sizing has been used as an efficient method to measure grain size compared to traditional methods. However, current automatic detection methods based on image intensity have limitations in suboptimal environments. In this study, a convolutional neural network model called GrainID was proposed to measure grain size in diverse fluvial environments. Tests showed that GrainID had high predictive accuracy and outperformed other methods, even in uncalibrated rivers with drone images. GrainID also showed less variation in results and was less affected by vegetation and noise.
EARTH SURFACE DYNAMICS
(2022)
Article
Water Resources
Yuntian Song, Xudong Fu, Yongpeng Lin, Chenge An, Hongbo Ma
Summary: This study investigates the breach events of barrier lakes on the Jinsha River and the Yarlung Zangbo River in China through numerical simulations. The researchers establish a physically-based dam-breach model for prediction and find that the magnitude and shape of the outburst flood hydrograph can be affected by dam morphology and dam material composition. Two patterns of outburst flood hydrographs with different symmetry characteristics are identified.
FRONTIERS IN WATER
(2022)