Hanoi, Vietnam

Water Resources University is a university in Hanoi, Vietnam. The university was established in 1959 as the Electricity Water Resources Academy, spun off from the mother university Hanoi University of Technology. The university now has three campuses in Hanoi with a large campus in Ho Chi Minh City and a campus in Phan Rang-Tháp Chàm, Ninh Thuan Province. The university offers undergraduate and postgraduate programs in: water resources management, dam construction, irrigation, flood control, environmental management, civil construction, and hydroelectricity. Wikipedia.

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Le D.-H.,Water Resources University | Kwon Y.-K.,University of Ulsan
Computational Biology and Chemistry | Year: 2012

Finding genes associated with a disease is an important issue in the biomedical area and many gene prioritization methods have been proposed for this goal. Among these, network-based approaches are recently proposed and outperformed functional annotation-based ones. Here, we introduce a novel Cytoscape plug-in, GPEC, to help identify putative genes likely to be associated with specific diseases or pathways. In the plug-in, gene prioritization is performed through a random walk with restart algorithm, a state-of-the art network-based method, along with a gene/protein relationship network. The plug-in also allows users efficiently collect biomedical evidence for highly ranked candidate genes. A set of known genes, candidate genes and a gene/protein relationship network can be provided in a flexible way. © 2012 Elsevier Ltd.

Le D.-H.,University of Ulsan | Le D.-H.,Water Resources University | Kwon Y.-K.,University of Ulsan
Bioinformatics | Year: 2013

Motivation: Many studies have investigated the relationship between structural properties and dynamic behaviors in biological networks. In particular, feedback loop (FBL) and feedforward loop (FFL) structures have received a great deal of attention. One interesting and common property of FBL and FFL structures is their coherency of coupling. However, the role of coherent FFLs in relation to network robustness is not fully known, whereas that of coherent FBLs has been well established.Results: To establish that coherent FFLs are abundant in biological networks, we examined gene regulatory and signaling networks and found that FFLs are ubiquitous, and are in a coherently coupled form. This result was also observed in the species-based signaling networks that are integrated from KEGG database. By using a random Boolean network model, we demonstrated that these coherent FFLs can improve network robustness against update-rule perturbations. In particular, we found that coherent FFLs increase robustness because these structures induce downstream nodes to be robust against update-rule perturbations. Therefore, coherent FFLs can be considered as a design principle of human signaling networks that improve network robustness against update-rule perturbations. © 2013 The Author Published by Oxford University Press. All rights reserved.

Cardenas M.B.,University of Texas at Austin | Jiang X.-W.,Water Resources University
Water Resources Research | Year: 2010

In this paper, we investigate the effects of systematic and local heterogeneity on groundwater flow, transport, and residence time distributions (RTDs) of basins where groundwater flow is topography driven. Systematic heterogeneity is represented by an exponentially depth-decreasing hydraulic conductivity and porosity, and local heterogeneity is represented by the dispersivity. The RTDs for both a simple basin with one flow system and a basin with nested local and regional systems gradually evolve to a power law RTD with more pronounced systematic heterogeneity. Exponential decrease of poromechanical properties enhances shallow circulation and subdues deep and regional flows leading to longer flushing times for the large part of the domain, while the shallower portions flush solutes rapidly. Therefore, deeper basins lead to more persistent and pronounced power law RTDs when the poromechanical properties systematically decrease with depth. Separate contributions to the RTD due to stagnation zones associated with local flow cells and due to deeper immobile zones were identified; each leads to a different tailing behavior. Local heterogeneity slightly enhances the power law RTD by causing the tailing to begin earlier but does not affect the late time portion of the RTD. Systematic depth-dependent heterogeneity is an important factor controlling the circulation and associated RTDs of subsurface fluids. It contributes significantly to generation of power law RTDs. © 2010 by the American Geophysical Union.

Li H.,Temple University | Boufadel M.C.,Water Resources University
Nature Geoscience | Year: 2010

Oil spilled from the tanker Exxon Valdez in 1989 (refs1, 2) persists in the subsurface of gravel beaches in Prince William Sound, Alaska. The contamination includes considerable amounts of chemicals that are harmful to the local fauna3. However, remediation of the beaches was stopped in 1992, because it was assumed that the disappearance rate of oil was large enough to ensure a complete removal of oil within a few years. Here we present field data and numerical simulations of a two-layered beach with a small freshwater recharge in the contaminated area, where a high-permeability upper layer is underlain by a low-permeability lower layer. We find that the upper layer temporarily stored the oil, while it slowly and continuously filled the lower layer wherever the water table dropped below the interface of the two layers, as a result of low freshwater recharge from the land. Once the oil entered the lower layer, it became entrapped by capillary forces and persisted there in nearly anoxic conditions that are a result of the tidal hydraulics in the two-layered beaches. We suggest that similar dynamics could operate on tidal gravel beaches around the world, which are particularly common in mid- and high-latitude regions4,5, with implications for locating spilled oil and for its biological remediation. © 2010 Macmillan Publishers Limited. All rights reserved.

Thirty year normal (1981-2010) monthly latent heat fluxes (ET) over the conterminous United States were estimated by a modified Advection-Aridity model from North American Regional Reanalysis (NARR) radiation and wind as well as Parameter-Elevation Regressions on Independent Slopes Model (PRISM) air and dew-point temperature data. Mean annual ET values were calibrated with PRISM precipitation (P) and validated against United States Geological Survey runoff (Q) data. At the six-digit Hydrologic Unit Code level (sample size of 334) the estimated 30 year normal runoff (P - ET) had a bias of 18 mm yr-1, a root-mean-square error of 96 mm yr-1, and a linear correlation coefficient value of 0.95, making the estimates on par with the latest Land Surface Model results but without the need for soil and vegetation information or any soil moisture budgeting. © 2015. American Geophysical Union.

Wang J.,Water Resources University | He J.,Water Resources University | Chen H.,Water Resources University
Science of the Total Environment | Year: 2012

Groundwater contamination risk assessment is an effective tool for groundwater management. Most existing risk assessment methods only consider the basic contamination process based upon evaluations of hazards and aquifer vulnerability. In view of groundwater exploitation potentiality, including the value of contamination-threatened groundwater could provide relatively objective and targeted results to aid in decision making. This study describes a groundwater contamination risk assessment method that integrates hazards, intrinsic vulnerability and groundwater value. The hazard harmfulness was evaluated by quantifying contaminant properties and infiltrating contaminant load, the intrinsic aquifer vulnerability was evaluated using a modified DRASTIC model and the groundwater value was evaluated based on groundwater quality and aquifer storage. Two groundwater contamination risk maps were produced by combining the above factors: a basic risk map and a value-weighted risk map. The basic risk map was produced by overlaying the hazard map and the intrinsic vulnerability map. The value-weighted risk map was produced by overlaying the basic risk map and the groundwater value map. Relevant validation was completed by contaminant distributions and site investigation. Using Beijing Plain, China, as an example, thematic maps of the three factors and the two risks were generated. The thematic maps suggested that landfills, gas stations and oil depots, and industrial areas were the most harmful potential contamination sources. The western and northern parts of the plain were the most vulnerable areas and had the highest groundwater value. Additionally, both the basic and value-weighted risk classes in the western and northern parts of the plain were the highest, indicating that these regions should deserve the priority of concern. Thematic maps should be updated regularly because of the dynamic characteristics of hazards. Subjectivity and validation means in assessing the vulnerability result were also discussed. In addition, GIS technology was essential in completing the assessment work. © 2012 Elsevier B.V.

Since the recent High Level Meeting on National Drought Policy held in Geneva in 2013, a greater concern about the creation and adaptation of national drought monitoring systems is expected. Consequently, backed by international recommendations, the use of Standardized Drought Indices (SDI), such as the Standardized Precipitation Index (SPI), as an operational basis of drought monitoring systems has been increasing in many parts of the world. Recommendations for the use of the SPI, and consequently, those indices that share its properties, do not take into account the limitations that this type of index can exhibit under the influence of multidecadal climate variability. These limitations are fundamentally related to the lack of consistency among the operational definition expressed by this type of index, the conceptual definition with which it is associated and the political definition it supports. Furthermore, the limitations found are not overcome by the recommendations for their application. This conclusion is supported by the long-term study of the Standardized Streamflow Index (SSI) in the arid north-central region of Chile, under the influence of multidecadal climate variability. The implications of the findings of the study are discussed with regard to their link to aspects of drought policy in the cases of Australia, the United States and Chile. © 2014 Elsevier B.V.

Tuan T.Q.,Water Resources University
Coastal Engineering Journal | Year: 2013

Extensive laboratory experiments were carried out to investigate the efficiency of low (vertical) crown-walls on the reduction of wave overtopping on sea-dikes. It is shown that the reduction of wave overtopping discharge by crown-walls is inadequately described in the TAW-2002 guidelines. A new approach for the wall influence has therefore been developed, explicitly taking into account both the wall height and the promenade width. The approach can straightforwardly be incorporated in the original formulations of TAW-2002 to significantly improve the prediction of wave overtopping on sea-dikes crowned with this type of walls. © 2013 World Scientific Publishing Company and Japan Society of Civil Engineers.

Ardhuin F.,French Research Institute for Exploitation of the Sea | Roland A.,Water Resources University
Journal of Geophysical Research: Oceans | Year: 2012

Coastal reflection is introduced in a phase-averaged numerical wave model, first with a constant coefficient, and then with a reflection coefficient defined from the shoreface slope and that depends on the incident wave height and mean frequency. This parameterization is used in both regular and unstructured grids. The calibration involves a site-specific shoreface slope that is associated with the local geomorphology of the shoreline. Using wave buoy data off Hawaii and the U.S. West Coast, it is found that coastal reflection is necessary to reproduce observed directional properties of coastal sea states. Errors on the mean directional spread are reduced by up to 30% for the frequency band 0.04 to 0.30 Hz with, at most locations, very little impact on the mean direction and energy levels. The most accurate results are obtained using the parameterization based on the shoreface slope, provided that this slope is estimated accurately. These parameterizations are validated using seismic noise data. Using data from the U.S. West Coast it is shown that the reflection defined from the shoreface slope can improve the correlation between measured and modeled seismic noise. © 2012 American Geophysical Union. All Rights Reserved.

Chen C.-Y.,Water Resources University
Journal of Mountain Science | Year: 2012

Defining a basin under a critical state (or a self-organized criticality) that has the potential to initiate landslides, debris flows, and subsequent sediment disasters, is a key issue for disaster prevention. The Lushan Hot Spring area in Nantou County, Taiwan, suffered serious sediment disasters after typhoons Sinlaku and Jangmi in 2008, and following Typhoon Morakot in 2009. The basin's internal slope instability after the typhoons brought rain was examined using the landslide frequency-area distribution. The critical state indices attributed to landslide frequency-area distribution are discussed and the marginally unstable characteristics of the study area indicated. The landslides were interpreted from Spot 5 images before and after disastrous events. The results of the analysis show that the power-law landslide frequency-area curves in the basin for different rainfall-induced events tend to coincide with a single line. The temporal trend of the rainfall-induced landslide frequency-area distribution shows 1/f noise and scale invariance. A trend exists for landslide frequency-area distribution in log-log space for larger landslides controlled by the historical maximum accumulated rainfall brought by typhoons. The unstable state of the basin, including landslides, breached dams, and debris flows, are parts of the basin's self-organizing processes. The critical state of landslide frequency-area distribution could be estimated by a critical exponent of 1. 0. The distribution could be used for future estimation of the potential landslide magnitude for disaster mitigation and to identify the current state of a basin for management. © 2012 Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag Berlin Heidelberg.

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