Floodplain hydrology of the Mekong Delta,Vietnam     

Nguyen Nghia Hung  José Miguel Delgado  Vo Khac Tri  Le Manh Hung  Bruno Merz  András Bárdossy  Heiko Apel 《水文研究》2012,26(5):674-686

The Mekong Delta is one of the largest and most intensively used estuaries in the world. Each year it witnesses widespread flooding which is both the basis of the livelihood for more than 17 million people but also the major hazard. Therefore, a thorough understanding of the hydrologic and hydraulic features is urgently required for various planning purposes. While the general causes and characteristics of the annual floods are understood, the inundation dynamics in the floodplains in Vietnam which are highly controlled by dikes and other control structures have not been investigated in depth. Especially, quantitative analyses are lacking, mainly due to scarce data about the inundation processes in the floodplains. Therefore, a comprehensive monitoring scheme for channel and floodplain inundation was established in a study area in the Plain of Reeds in the northeastern part of the Vietnamese Delta. This in situ data collection was complemented by a series of high‐resolution inundation maps derived from the TerraSAR‐X satellite for the flood seasons 2008 and 2009. Hence, the inundation dynamics in the channels and floodplains, and the interaction between channels and floodplains, could be quantified for the first time. The study identifies the strong human interference which is governed by flood protection levels, cropping patterns and communal water management. In addition, we examine the tidal influence on the inundation in various parts of the Delta, since it is expected that climate change‐induced sea level rise will increase the tidal contribution to floodplain inundation. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Simultaneous identification of parameter,initial condition,and boundary condition in groundwater modelling     

Hung‐Jen Liu  Nien‐Sheng Hsu  Tim Hau Lee 《水文研究》2009,23(16):2358-2367

In this paper, we perform an inverse method to simultaneously estimate aquifer parameters, initial condition, and boundary conditions in groundwater modelling. The parameter estimation is extended to a complete inverse problem that makes the calibrated groundwater flow model more realistic. The adjoint state method, the gradient search method, and the least square error algorithm are combined to build the optimization procedure. Horizontal two‐dimensional groundwater flow in a confined aquifer is exemplified to demonstrate the correlation between unknowns, the contribution of observation, as well as the suitability of applying the inverse method. The correlation analysis shows the connection between storage coefficient and initial condition. Besides, transmissivity and boundary conditions are also highly correlated. More observations at different location and time are necessary to provide sufficient information. A time series of unsteady head is requested for estimation of storage coefficient and initial condition. Observation near boundary is very effective for boundary condition estimation. The observation at pumping well mostly contributes to the estimation of transmissivity. According to all observations, it is possible to identify parameters, initial condition, and boundary condition simultaneously. Furthermore, the results not only illustrate the traditional assumption of known boundary condition but also initial condition, which may cause an incorrect estimation. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Life span of a landslide dam on mountain valley caught on seismic signals and its possible early warnings     

Yang  Che-Ming  Chang  Jui-Ming  Hung  Chi-Yao  Lu  Chih-Heng  Chao  Wei-An  Kang  Keng-Hao 《Landslides》2022,19(3):637-646

Landslides - Outburst flooding after a landslide dam breach causes global fatalities and devastation. Information on the timing, magnitude, and location of the landslide dam is crucial to hazard...  相似文献   

Reverse fault slip through soft rock and sand strata by centrifuge modeling tests     

Hung  Wen-Yi  Soegianto  Dicky Pratama  Wang  Yi-Hsiu  Huang  Jun-Xue 《Acta Geotechnica》2022,17(8):3337-3356

The devastating damage after the 1999 Chi-Chi and 1999 Izmit earthquakes has greatly motivated soil–reverse fault interaction studies. However, most centrifuge modeling studies have employed a single homogeneous soil layer during testing, which does not represent in situ conditions. Indeed, while geological conditions vary spatially, engineering soils are often underlain by soft rocks. Therefore, four centrifuge models were developed to evaluate the effect of soft rock layers on the ground surface and subsurface deformation. Sand–cement mixtures of varying thicknesses with a uniaxial compressive strength of 0.975 MPa, simulating extremely soft rock, were overlain by pluviated sandy soil. The model thickness was 100 mm, corresponding to 8 m in the prototype scale when spun at 80 g. Every model was subjected to a vertical offset of 50 mm/4 m (0.5 H; H: total sedimentary deposit thickness) along a reverse fault with a 60° dip. The results indicate that the presence of a soft rock stratum results in the creation of a horst profile at the ground surface. Additionally, the thinner the soil layer on top of the soft rock stratum is, the longer and higher the horst created at the ground surface. Consequently, the fault deformation zone lengthens proportionally with the increasing thickness ratio of the soft rock. Furthermore, the presence of soft rock as an intermediary stratum between bedrock and soil causes the deformation zone boundary on the hanging wall side to move in the direction of fault movement.

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Topographic zonation of infiltration in the hilly loess region,north china     

Gang Li  Shiu Hung Luk  Qiang Guo Cai 《水文研究》1995,9(2):227-235

Field infiltration tests using portable rainfall infiltrometers were conducted in the Wangjiagou experimental basin in the hilly loess region of north China. Based on data collected at 27 sites, a topographic zonation of infiltration characteristics was observed. The average steady infiltration rate and the average ponding time decreased from the hilltop to the hillslope and further decreased to the gully wall. Such a zonation is closely related to the variations of topography, soil and land use conditions in the study area. A general infiltration model is proposed. Collected field data are used to establish the applicability of the proposed model in the study area.  相似文献   

Mapping and Assessing Landfills Surface Temperature Using Landsat 8 Satellite Data. A Case Study in Vietnam     

Le Hung Trinh  Zablotskii  V. R.  Vu  Danh Tuyen  Zenkov  I. V.  Tong  Thi Hanh 《Izvestiya Atmospheric and Oceanic Physics》2021,57(9):1098-1107

Izvestiya, Atmospheric and Oceanic Physics - In recent years, rapid urbanization and population growth have led to an overload of waste in big cities of Vietnam. Waste decomposition is always...  相似文献   

Multi-objective optimal design for flood risk management with resilience objectives   总被引：1，自引：1，他引：0  

Hsin-Ting?Su  Sai?Hung?CheungEmail author  Edmond?Yat-Man?Lo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(4):1147-1162

In flood risk management, the divergent concept of resilience of a flood defense system cannot be fully defined quantitatively by one indicator and multiple indicators need to be considered simultaneously. In this paper, a multi-objective optimization (MOO) design framework is developed to determine the optimal protection level of a levee system based on different resilience indicators that depend on the probabilistic features of the flood damage cost arising under the uncertain nature of rainfalls. An evolutionary-based MOO algorithm is used to find a set of non-dominated solutions, known as Pareto optimal solutions for the optimal protection level. The objective functions, specifically resilience indicators of severity, variability and graduality, that account for the uncertainty of rainfall can be evaluated by stochastic sampling of rainfall amount together with the model simulations of incurred flood damage estimation for the levee system. However, these model simulations which usually require detailed flood inundation simulation are computationally demanding. This hinders the wide application of MOO in flood risk management and is circumvented here via a surrogate flood damage modeling technique that is integrated into the MOO algorithm. The proposed optimal design framework is applied to a levee system in a central basin of flood-prone Jakarta, Indonesia. The results suggest that the proposed framework enables the application of MOO with resilience objectives for flood defense system design under uncertainty and solves the decision making problems efficiently by drastically reducing the required computational time.  相似文献   

Satellite-based monitoring of contrasting characteristics of suspended sediment discharged from the Red and the Ma river systems along the northern coast of Vietnam     

Yoshimitsu Tajima  Kavinda Gunasekara  Hung Thanh Nguyen 《国际泥沙研究》2019,34(3):191-204

The northern coast of Vietnam has accumulated a significant amount of sediment discharged from the multiple distributaries of rivers such as the Red River and Ma River.While recent decreases of the sediment supply appears to have a significant impact on coastal erosion,the complex network of these distributaries makes it difficult to determine the overall spatiotemporal characteristics of sediment discharges and related topographic changes.The goal of the current study is to develop a satellite-based monitoring system for observation of turbidity discharged from the multiple rivers and to investigate the applicability of the developed monitoring system through a case study on the northern coast of Vietnam.Based on the in-situ observed data,a formulawas determined for estimation of the surface water turbidity as a function of the red band reflectance of Moderate Resolution Imaging Spectro-radiometer(MODIS)images.The formula was then combined with a newly determined threshold for cloud-masking to obtain maps of the nearshore turbidity patterns.These maps capture the spatiotemporal water surface turbidity along the entire coast of the Red River Delta and the coast around theMa River mouth over the past sixteen years with frequency of twice a day.Finally,long-term trends of the turbidity patterns from multiple rivers were compared with the in-situ observation data and it was found that the Red River and the Ma River showed clearly contrasting characteristics,which reasonably explain the recent coastal shoreline changes and characteristics of sediment sampled along the coast.  相似文献   

The Kellwasser events in the Upper Devonian Frasnian to Famennian transition in the Toc Tat Formation,northern Vietnam     

Toshifumi Komatsu  Ryota Urakawa  Toshitaka Inada  Kazuki Yamauchi  Takumi Maekawa  Reishi Takashima  Mark Williams  Phong D. Nguyen  Hung D. Doan  Minh T. Nguyen  Shuji Niko  Gengo Tanaka  Tatsuhiko Yamaguchi 《Island Arc》2019,28(1)

Upper Devonian carbonates of the Toc Tat Formation in the Si Phai Pass area of Dong Van District, northern Vietnam were deposited in carbonate platform, slope, and basin environments. These carbonates yield abundant conodonts indicative of the Palmatolepis nasuta, Pa. linguiformis and Pa. triangularis zones, the Frasnian–Famennian stage boundary being identified by the first occurrence of Pa. triangularis. Two positive carbon isotope excursions are recognized, the lower excursion peaking in the interval of the lower to middle Pa. nasuta Zone, whilst the upper excursion peaks just above the local Frasnian–Famennian boundary. Based on the biostratigraphy, these excursions equate to the Lower and Upper Kellwasser events. Locally, tentaculitoid taxa (Nowakia, Styliolina, Homoctenus, and Metastyliolina?) are abundant in the interval of the Pa. nasuta Zone, but show a drastic decline in abundance before the Lower Kellwasser Event, and only two taxa survived into the Famennian.  相似文献   

Multi‐dimensional analyses of the SEAM controlled source electromagnetic data—the story of a blind test of interpretation workflows          下载免费PDF全文

Hung‐Wen Tseng  Jack Stalnaker  Lucy M. MacGregor  Rolf V. Ackermann 《Geophysical Prospecting》2015,63(6):1383-1402

Using a subset of the SEG Advanced Modeling Program Phase I controlled‐source electromagnetic data, we apply our standard controlled‐source electromagnetic interpretation workflows to delineate a simulated hydrocarbon reservoir. Experience learned from characterizing such a complicated model offers us an opportunity to refine our workflows to achieve better interpretation quality. The exercise proceeded in a blind test style, where the interpreting geophysicists did not know the true resistivity model until the end of the project. Rather, the interpreters were provided a traditional controlled‐source electromagnetic data package, including electric field measurements, interpreted seismic horizons, and well log data. Based on petrophysical analysis, a background resistivity model was established first. Then, the interpreters started with feasibility studies to establish the recoverability of the prospect and carefully stepped through 1D, 2.5D, and 3D inversions with seismic and well log data integrated at each stage. A high‐resistivity zone is identified with 1D analysis and further characterized with 2.5D inversions. Its lateral distribution is confirmed with a 3D anisotropic inversion. The importance of integrating all available geophysical and petrophysical data to derive more accurate interpretation is demonstrated.  相似文献