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• Assessing Land Use and Land Cover Change: A Case of Tien Yen District, Quang Ninh Province from 2000 to 2010

  Nguyen Thi Thu Hien, Pham Vong Thanh, Nguyen Khac Thoi

  Received: 14-11-2013 / Accepted: 21-02-2013

   Abstract PDF (VIETNAMESE)

  The study was conducted to assess land useand land cover change in Tien Yen district in the 2000 -2010 period using SPOT images which were acquired in years 2000, 2005 and 2010. The object –oriented approach which was applied in this research includedtwomain steps: firstly, SPOT image was fragmented to vary objects by eCognition software, and, secondly,the segmentation images were classified by Maximum Likelihood approach using training dataset. The samples consisting of nineland usetypeswere collected by handheld GPSdevice. The overall accuracy of 3 image classifications in 2000, 2005, 2010 were 82.74%, 80,97% and 89.33%, respectively. Land useand land cover mapand land use/land cover change map were produced by ArcGIS (version 10.0) software to assess the land use change of the study area. Within 10 yearsperiod, the forest area and mangrove forest increased 3916.91ha and 1720.57ha, respectively. Meanwhile, the swidden and shrublanddecreased 4200.16ha. The increase of forest area in Tien Yen might be explained bybetter awarenessof local people about the benefits and the importance of forest as well as by thethe implementation of national and international projects which support Tien Yen in protecting and developing forest resource.

• Application of Remote Sensing and Geographical Information Systemin Mapping Land Cover ofSrepok Watershed in Central Highland

  Nguyen Thi Ngoc Quyen, Nguyen Cong Tai Anh, Bui Ta Long, Nguyen Kim Loi

  Received: 30-11-2015 / Accepted: 05-05-2016

   Abstract PDF (VIETNAMESE)

  Management of natural resources in accordance with river basin is an indispensable trend towards sustainable resource management and use. However, in Vietnam, the resources are managed based on administrative boundaries. Therefore, the information and data are scattered in many places with different quality and not willing to be shared, making them unavailable for scientific research. In the present study, remote sensing combined with GIS was used for building the land cover map to correct the input data with regard to Srepok watershed. The process of analysis and classification for Landsat 8 OLI in Srepok watershed in 2015 yielded reliable results with the Kappa coefficient over 0.69 and overall accuracy of 73.53%. As a result, land cover map was produced in Srepok watershed with seven different classes including evergreen forest, deciduous forest, mixed forest, perennial trees, annual crops and specialized land and water surface.

• Constructing Map of Agricultural Soil Erosion Risk by Spatial Analysis Technique of GIS in Tam Nong District, Phu Tho Province

  Nguyen Thi Thu Hien, Tran Quoc Vinh

  Received: 17-05-2017 / Accepted: 10-08-2017

   Abstract PDF (VIETNAMESE)

  Soil erosion is one of the main causesof soil degradation. Map of soil erosion risk provides information about location and erosionthreat, thus helpsus incontrolling the impact factors of soil erosion. The aim of this study was to apply spatial analysis methods in GIS to produce the map of soil erosion risk for agricultural land in Tam Nong district, Phu Tho province. Based on expert’s knowledge, followed by Analytic hierarchy process (AHP), we calculated the weight for 5 impact factors to soil erosion: precipitation (49.22%), slope (20.57%), soil types (10.30%), vegetation cover (13.48%) and land use type (6.44%). Spatial analysis techniques were used to over lay all thematic maps with corresponding weights to construct map of soil erosion risk. The results showed, there were 1 650.78 ha of agricultural land that hadhigh risk of erosion (accountingfor 15.16% of the total area)and3 074.07 (28.23%) ha hadmedium risk. The agricultural land with low and no risk of soil erosion accountedfor 40.58% and 16.03%,respectively. Verification in the field indicated that the map of soil erosion risk has high reliability, and reflects the reality of the soil erosion in the study area.

• Impact of Coal Mining on Landscape, Environment and Land Usein Ha Long City, Quang Ninh Province

  Vu Thang Phuong, Do Nguyen Hai, Vo Tu Can

  Received: 26-06-2018 / Accepted: 02-08-2018

   Abstract PDF (VIETNAMESE)

  This study was conducted to assess the impact of coal mining on landscape, environment and land use in Ha Long City. The methods used for collecting data collection were secondary materials, field survey, household interview, map editing and data statistics, and soil and water sampling and analysis. Results showed that coal mining seriously affected land use. In the 2010 -2017 period, the area of coal mining has increased by 740.13 hectares while forest area decreased by 520.44 hectares and land cover decreased 15.12%. Soil quality also degraded due tpcoal mining. The contentsof heavy metals (As, Pb Cu, Zn, and Cd) of coal waste dump sites weremuch higher than these of agricultural cultivated sites according to QCVN 03-MT:2015/MONREstandards. Particularly As was 5.4 to 9.45 times higher than QCVN 03-MT:2015/MONREstandard. Coal mining increased contents of Fe, Mn, TSS (total suspended solids) and COD and decreased pH in both surface water and in ground water systems. Moreover, coal mining activities resulted in increased landslides, landfill, and landform change, which accelerate natural disaster risks and landscape degradation in tourist areas in Ha Long city and in Ha Long Bay UNESCO’s World Heritage.