Some Research Results f-rom the Application of Geophysical Methods in Quickly Identifying Shallow Hazards in Dike and Dam Body
Abstract: Small and shallow caves are frequently found on the dike and dam system inside our country, leading to some risks of subsidence, seepage, even dyke and dam rupture. The handling of this problem is relatively simple if we can accurately identify the location of these hollow caves. The question is how to study and find out the geophysical method to quickly and accurately determine the location and size of these caves for timely treatment in order to improve the efficiency of the survey. This paper presents some new results obtained when studying and applying the Improved multi-electrode (2D and 3D) and Ground penetrating radar methods to rapidly determine the hollow caves at K112+697 position of the Red River right dam in Hà Nội and at K21+900 position of Dao River left dam in Nam Định. The paper also assesses the capability and effectiveness of each method in the determination of this object.
Keywords:Hollow cave, termite, sinkhole, Improved multi-electrode, Ground penetrating radar..
Bản toàn văn: http://tapchi.vnu.edu.vn/upload/2014/01/1039/6.pdf
Lithofacies Analysis and Reconstruction of Deformation Types of Cenozoic Sediments of Phú Khánh Basin
Abstract: F-rom Oligocene and Quaternary geological sedimentary section have six cycles corresponding to six sequences: - Sequence 1: Eocene - early Oligocene (E2 – E 3 1 ); - Sequence 2: Late Oligocene (E3 2 ); - Sequence 3: Early Miocene (N1 1 ); - Sequence 4: Middle Miocene (N1 2 ); - Sequence 5: Late Miocene (N1 3 ); - Sequence 6: Pliocene - Quaternary (N2 - Q). Since then may establish three general integrated formulas between the lithofacies association series and sedimentary systems tract as follows: 1. Sedimentary lowstand systems tract (LST): LST = arLST + (ar + amr)LST + (amt + mt)/(amr + mr) LST + mrLST (1); 2. Sedimentary transgressive systems tract (TST): TST = MtTST + atTST + (amr + mr)/(mt + amt)TST + mtTST (2); 3. Sedimentary highstand systems tract (HST): HST = arHST + (ar + amr)HST + (amt+mt)/ (amr +mr)HST + mrHST (3).
Keywords: Sequence, lowstand, highstand, transgressive systems tract, parasequence set, parasequence, marine flooding plain.
Bản toàn văn: http://tapchi.vnu.edu.vn/upload/2014/01/1038/5.pdf
Development of an Online Supporting System Flood Warning for Vu Gia Watershed, Quảng Nam Province, Vietnam: Conceptual Framework and Proposed Research Techniques
Abstract: Vu Gia Watershed is located in the Central Vietnam whe-re hurricanes pose a constant natural threat to human lives and physical infrastructure. Hydrological monitoring is considered as an effective tool to respond to high floods by preventing and mitigating the losses. The purpose of this study was to conduct and perform hydrological modeling to determine the flood-prone areas during the high rainfall season in the upstream Vu Gia Watershed. The methodology involved: hydro-climatic database building, a detailed Digital Elevation Model (DEM), a land use cover, and a soil map of the basin. With all these data, the SWAT model (Soil and Water Assessment Tool) was used to predict disc-harge values. These disc-harge values were used, along with the DEM, to predict flood hazard areas in the downstream of Vu Gia Watershed floodplains. This procedure was made using the HEC-RAS model (Hydrological Engineering Center-River Analysis System). The results show the exact location of areas with high, moderate and low risk, which are to be flooded at specific high floods. The results also provide the location in critical situation, so that an early warning system can be located. Additionally, as a part of this study, valuable information about how to prevent and mitigate the affects of flood-related damage was provided to residents at risk in the low land areas of the Vu Gia Watershed.
Keywords: Flood warning, SWAT, HEC-RAS, Vu Gia Watershed, Quảng Nam Province.
Bản toàn văn: http://tapchi.vnu.edu.vn/upload/2014/01/1037/4.pdf
Assessment of Flood Hazard in Hanoi City
Abstract: This paper presents the results of studying flood hazard and vulnerability caused by flood and flood hazard in Hanoi City. By analyzing satellite images, using GIS and geomorphological features, the authors had assessedthe actual state of historical flood happening at the end of 2008. The results show that most of Hanoi’s flat areas are 0-4m submersible in water. Effective level of inundation increases gradually f-rom two sides into the centre and f-rom the north to the south, consistent with obliquity and terrainc-haracteristics of Hanoi City. Some areas in the west, southwest and south of the city (in districts: Chương Mỹ, Mỹ Đức, Ứng Hòa, Thường Tín, Phú Xuyên) are severely affected by flood with deeply inundated areas; inundation level is at danger level of about 2-4m. The districts in the south of Hanoi have the most vulnerable areas, such as the low lands: Mỹ Đức, Ứng Hòa, Thường Tín, Chương Mỹ, Thanh Oai districts. Chương MỹDistrict has 117ha at very high-risk level; Ứng Hòa District has 87 ha. In the inner city, Hà Đông, Hai Bà Trưng and Tây Hồdistricts have the highest hazard level. The suburban districts in the south of Hanoi haven the largest agricultural and rural residential land, which are often in deep and prolonged inundation, so the flood risk here isalso at high level.
Keywords: Flood, inundation, flood risk hazard, Hanoi City
Bản toàn văn: http://tapchi.vnu.edu.vn/upload/2014/01/1036/3.pdf
Some Difficulties and Suggestions for Sustainable Marine Eco-tourism in Vietnam and Japan: Case Studies of Vân Đồn District, Quảng Ninh Province and Akkeshi Town, Hokkaido
Abstract. The paper deals with the difficulties in developingsustainable marine eco-tourism based on analysis of current situation in two case studies in Japan and Vietnam. Akkeshi Town is located in the northeastern part of Hokkaido, whe-re the natural resources are abundant, such as the Ramsar inscribed wetland, the existence of big mammals such as seals. However, the town is facing the decrease in the number of visitors after a high expectation in the 1990s due to an out-of the way place. Vân Đồn District, on the other hand, is a new and prospective project in the government’s policy to stimulate the economy of the coastal zoneof Quảng Ninh. It owns a national park that offers a lot of natural resources but a proper way is yet to be found to make it conform with the exploitation of tourism industry. Besides the diversity in geographical features, it is also the habitat of some kinds of tortoises and other special animals. Nevertheless, both cases have similar paradoxes in tourism development, first f-rom the objective contexts (e.g. the competition with their neighboring areas that have quite similar natural resources) and secondly, f-rom the subjective paradigms (e.g. the high seasonableness and dependency on natural conditions). How to minimize the difficulties to support the development of ecotourism is the question that needs correct answers. Based on the authors’ experience in tourism industry, some solutions are suggested, including co-operation within local tourism, the proactive leadership of local government, the business model for sustainable management, as well as considering the interaction relationship between mass tourism and ecotourism as a solution for current development.
Keywords: Ecotourism, sustainable tourism, tourism management, Vietnam, Japan.
Bản toàn văn: http://tapchi.vnu.edu.vn/upload/2014/01/1035/2.pdf
Designing a WebGIS System to Support Active Participation of Citizens in Land Use Planning
Abstract: The effectiveness of a land use planning (LUP) system depends largely on its transparency. In this context, the Vietnamese LUP system is often being criticized for the insignificant participation of the local community in developing and implementing land use plans. To cope with this problem, the authors have developed a LUP WebGIS system to provide a government-to-citizen communication channel and enhance active participation of the local community in LUP. Based on an open source platform (PostgreSQL/PostGIS, MapServer, pMapper, and Apache), the LUP WebGIS system allows the citizens to browse LUP and cadastral data, make and view feedbacks and proposals to LUP plans, exchange messages with governmental staff and other citizens, etc. The system was tested in Đông Anh District, Hanoi City and achieved positive results, though some modifications are required to better suit to the needs of the citizens.
Keywords: Land use planning; WebGIS; Public participation; Open source software; Đông Anh District.
Bản toàn văn: http://tapchi.vnu.edu.vn/upload/2014/01/1034/1.pdf
