Sedimentation in the floodplains of the Mekong Delta,Vietnam. Part I: suspended sediment dynamics          下载免费PDF全文

Nguyen Nghia Hung  José Miguel Delgado  Andreas Güntner  Bruno Merz  András Bárdossy  Heiko Apel 《水文研究》2014,28(7):3132-3144

Suspended sediment is the primary source for a sustainable agro‐ecosystem in the Mekong Delta by providing nutrient input for the subsequent cropping season. In addition, the suspended sediment concentration (SSC) plays an important role in the erosion and deposition processes in the Delta; that is, it influences the morphologic development and may counteract the deltaic subsidence and sea level rise. Despite this importance, little is known about the dynamics of suspended sediment in the floodplains of the Mekong Delta. In particular, quantitative analyses are lacking mainly because of data scarcity with respect to the inundation processes in the floodplains. In 2008, therefore, a comprehensive in situ system to monitor the dynamics of suspended sediment in a study area located in the Plain of Reeds was established, aiming at the characterization and quantification of suspended sediment dynamics in the deeply inundated parts of the Vietnamese part of the Mekong Delta. The monitoring system was equipped with seven water quality–monitoring stations. They have a robust design and autonomous power supply suitable for operation on inundated floodplains, enabling the collection of reliable data over a long period of time with a high temporal resolution. The data analysis shows that the general seasonal dynamics of suspended sediment transport in the Delta is controlled by two main mechanisms: the flood wave of the Mekong River and the tidal backwater influences from the coast. In the channel network, SSC decreases exponentially with distance from the Mekong River. The anthropogenic influence on SSC could also be identified for two periods: at the start of the floodplain inundation and at the end of the flood period, when subsequent paddy rice crops are prepared. Based on the results, we recommend an operation scheme for the sluice gates, which intends to distribute the sediment and thus the nutrients equally over the floodplain. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Predicting Blast-Induced Air Overpressure: A Robust Artificial Intelligence System Based on Artificial Neural Networks and Random Forest     

Nguyen  Hoang  Bui  Xuan-Nam 《Natural Resources Research》2019,28(3):893-907

Natural Resources Research - Blasting is the most popular method for rock fragmentation in open-pit mines. However, the side effects caused by blasting operations include ground vibration, air...  相似文献   

Vulnerability in north-central Vietnam: do natural hazards matter for everybody?     

Thorkil Casse  Anders Milhøj  Thao Phuong Nguyen 《Natural Hazards》2015,79(3):2145-2162

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A FEM-MPM hybrid coupled framework based on local shear strength method for simulating rainfall/runoff-induced landslide runout     

Zhu  Yulong  Ishikawa  Tatsuya  Zhang  Yafen  Nguyen  Binh T.  Subramanian  Srikrishnan Siva 《Landslides》2022,19(8):2021-2032

Landslides - Limited by the independence and its defects of each general software package, simultaneous analysis of runoff, seepage, and large-deformation analysis is still an inevitable challenge....  相似文献   

Calculation of seismic bearing capacity of shallow strip foundations using the cell-based smoothed finite element method     

Nguyen  H. C.  Vo-Minh  T. 《Acta Geotechnica》2022,17(8):3567-3590

This paper adopts an upper bound procedure using the cell-based smoothed finite element method (CS-FEM) to estimate the seismic bearing capacity of shallow strip footings, focussing on seismic soil-structure interactions. In simulations, soil behaviour is assumed as the Mohr–Coulomb material, and increment of plasticity deformation obeys the associated flow rule. The first step of the numerical procedure involves approximating the kinematically admissible displacement fields using the cell-based smoothed finite element method, while the second relates to the establishments of the optimization problem as the conic programming. The inclusion of seismic conditions in the simulations was made using the pseudo-static approach. Initially, three seismic bearing capacity factors were resolved for both smooth and rough foundations by including horizontal and vertical inertia forces caused by the soil weight, the superstructure and the surcharge in the analyses. All seismic bearing capacity components obtained are in excellent agreement with those obtained using the method of characteristics and other finite element analyses. Subsequently, the reduction coefficients that correlate static and seismic bearing capacity factors were computed to facilitate the seismic design of the foundation.

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Novel integrated approaches for predicting the compressibility of clay using cascade forward neural networks optimized by swarm- and evolution-based algorithms     

He  Ziguang  Nguyen  Hoang  Vu  Thai Ha  Zhou  Jian  Asteris  Panagiotis G.  Mammou  Anna 《Acta Geotechnica》2022,17(4):1257-1272

Acta Geotechnica - Soft soils are considered as disadvantages in construction, especially in clay layers. It requires many advanced techniques to treat the soft soils before construction, aiming to...  相似文献   

Real-time mesoscale forecast support during the CLAMS field campaign     

王东海 《大气科学进展》2007,24(4):599-605

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Modelling the Asian summer monsoon using CCAM   总被引：2，自引：1，他引：1  

Kim Chi Nguyen  John L. McGregor 《Climate Dynamics》2009,32(2-3):219-236

A ten-year mean (1989–1998) climatology of the Asian summer monsoon is studied using the CSIRO Conformal-Cubic Atmospheric Model (CCAM) to downscale NCEP reanalyses. The aim of the current study is to validate the model results against previous work on this topic, in order to identify model strengths and weaknesses in simulating the Asian summer monsoon. The model results are compared with available observations and are presented in two parts. In the first part, the mean summer rainfall, maximum and minimum temperatures and winds are compared with the observations. The second part focuses on validation of the monsoon onset. The model captures the mean characteristics such as the cross-equatorial flow of low-level winds over the Indian Ocean and near the Somali coast, rainfall patterns, onset indices, northward movements, active-break and revival periods.  相似文献   

Experimental and numerical behaviour of reinforced mortar plates subjected to accelerated corrosion     

Quang Thanh Nguyen  Sabine Caré  Yves Berthaud  Alain Millard  Frédéric Ragueneau 《国际地质力学数值与分析法杂志》2011,35(10):1141-1159

Most reinforced concrete structures are damaged due to corrosion of reinforcements in concrete. In normal conditions the pH near the reinforcements is around 12–13 which means that steel is in a passive state. But aggressive species, such as chloride ions or carbon dioxide, may penetrate into concrete and promote active corrosion. As a consequence (hydro)oxides are produced leading to degradation of concrete structures. For instance cracking of the concrete is generated due to the pressure induced by rust. In this paper, we study the inception and the propagation of cracking on reinforced mortar plates with rebars located either in the middle or at the corner. Additional experiments have been performed on cylindrical specimens to determine the local effect of rust pressure at the interface rust/mortar. The specimens have been subjected to imposed current density in order to enhance the corrosion and digital image intercorrelation has been used to determine displacement fields. The experiments have been compared to numerical modelling. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Determination of210Pb in volcanic gases and210Pb,226Ra,238U in lavas by non-destructive gamma-ray spectrometry     

Y. Yokoyama  H. Van Nguyen  G. Lambert 《Bulletin of Volcanology》1982,45(3):265-266

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