http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/65 2026-05-17T19:07:55Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/9203 Title: Numerical simulations of overland floods in urban areas using a conservative Godunov-type scheme Authors: Nguyen, Tat Thang Abstract: Floods in urban areas due to levee overtopping and/or breaking may cause a lot of severe damage of property and lost of human lives. In case of river dike and/or dam break, the problem is characterized by the overland propagation of discontinuity fronts or hydraulic jumps. !t is of immense importance that urban planners and personnel have tools to assist in predicting and evaluating beforehand the flood process in such incidents. Recently, with the rapid development of computer resources and numerical methods, numerical models based on mathematical models for simulation of flood scenarios become highly useful. A model for the simulation of two dimensional (20) overland floods in urban areas has therefore been developed. A finite volume Godunov-type numerical scheme is applied in the model. This numerical scheme has some important advantages. It is a conservative scheme and able to model more accurately hydraulic shockwave propagation. The scheme is based on unstructured computational meshes, in general, to deal with complicated urban geometries. The model has been applied to studying two experiments of overland floods. These experiments were carried out in research institutions in Japan and Italy. The computed results show general agreement with the measured ones. The model is prospective for analyzing overland flood process in practical cases. 2009-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/9202 Title: Applying SWAT model to simulate streamflow in Ben Hai River Basin in response to climate change scenarios Authors: Nguyen, Thanh Son; Nguyen, Ngoc Quy Abstract: SWAT model was used to assess the impacts of climate change on the streamflow of Ben Hai River Basin. The daily streamflow for 1979 - 1996 and 1997 - 2006 was used to calibrate and validate the SWAT model, respectively. Nash efficiency values for the daily comparison were 0.72 for the calibration period and 0.74 for the validation period. Three scenarios were analyzed relative to the baseline with 28-year time series. A doubling of the atmospheric C02 content to 660 ppm (while holding other climatic variables) resulted in a 7.2% increase in average annual streamflow while the average annual streamflow changes of 59.75%; 81.9%; 75% and 190% were predicted for two periods of B2 and A1FI scenarios respectively. The seasonal variability was predicted to be high for the individual climate change scenarios and in specific months the streamflow variability was also large between scenarios. The results also show that the hydrology of Ben Hai River Basin is sensitive to climate changes. 2009-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/9201 Title: Application of electronic Atlas for land management in Hanoi Authors: Bui, Ngoc Quy Abstract: Management of land is one of the very important tasks and a challenge for governments at all levels. In order to do a good land management work, many different instruments are needed, including maps. Presently, cadastral, land use and land use planning maps provide necessary land information for different users. These information need to be uploaded on the Internet to facilitate their access and use. In order to support this task, the establishment of websites and electronic maps on land information is necessary. Electronic atlas with ability of storing data in digital format, managing data by a database management system will allow to rapidly execute the data for determination of geographical coordinates, distance, perimeter, land cell area and other necessary information. The distribution of electronic atlas on internet also allows the access and search of the objects with given parameters. This article addresses the use of cartography, GIS and Multimedia technologies to establish The electronic atlas supporting; land management in Hanoi. It is the experiments of establishing and uploading electronic atlas to Web. The Atlas with information on land administration, land use and land use planning at district level is a useful instrument for the use and management of land by citizen and land management organizations. 2009-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/9200 Title: Natural resources and environment in Cam Ranh bay and sustainable development orientation Authors: Tran, Dang Quy; et al. Abstract: Locating in Khanh Hoa province, Cam Ranh bay is a typica1 bay for Southern Middle of Vietnam. The system of Cam Ranh bay has a plentiful natural resources, that divides into non­ biotic resources and biotic resources because of interaction between climate, hydology, geology, and topography conditions.. The first one includes position, wetland, mineral and geotope resources. The second one involves Ihe diversity of ecosystems such as mangrove, seagrass, coral reef and tidal wetland. However, all of them have been over exploiting for development of local economic, therefore, make them being degraded. The pressure of economical development are threating to Ihe sustainable of natural environment. Water has been contaminated by oi! and liable to contaminate by Pb, Hg, Mn, Sb. Sediment has been contaminated by As, PCBs, DDT and liable to contaminate by Hg. Therefore, it is necessary to orient for sustainable use of natural resources and enyironment system of Cam Ranh bay. Base on characteristics of natural resources and environments in Cam Ranh bay, sollutions in sustainable use of natural resources for the development of economies such as tourism, marine habours, fisheries, national seéurity, industria! zone, mineral exploiting has been proposed. Apart from the natural resources exploiting, sollutions in natural resources protection has also been considered such as to establish of protection areas; to protect sensitjve ecosystems, fisheries resources and to prevent environmental pollution and natural hazards. 2009-01-01T00:00:00Z