Application of remote sensing and GIS on landslide

THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURAL AND FORESTRY NGUYEN KIEU ANH APPLICATION OF REMOTE SENSING AND GIS ON LANDSLIDE RISK IN PAC NAM DISTRICT, BAC KAN PROVINCE THESIS PROPOSAL Study Mode: Full-time Major : Environmental Science and Management Faculty : International Program Office Batch : 2015-2019 Thai Nguyen, 09/2019 DOCUMENTATION PAGE WITH ABSTRACT Thai Nguyen University of Agriculture and Forestry Degree Program Bachelor of Environmental Science and Management Student name Nguyen Kieu Anh Student ID DTN1554290001 Thesis Title Application of remote sensing and GIS on landslide Supervisor (s) risk inNguyen Pac Nam district, Msc Van Hieu Bac Kan province Supervisor’s Signature Abstract: Pac Nam district is a mountainous district in Bac Kan province located in the North Eastern part of Vietnam Landslides occur frequently in this area and seriously affect local living conditions Especially, three households comprising 13 persons died in 2009 due to a landslide in Khen Len village of Cong Bang commune, Pac Nam district, Bac Kan province Hence, the analysis of landslide risk in this area is an important topic for both administrators and the local inhabitants In this study, landslide factor maps incorporating factors such as slope, rainfall, geological fault, soil types, traffic, land cover and distance to roads were used as input data to create a landslide risk map in Pac Nam district, Bac Kan province A weight number estimation method for landslide risk was applied to the study area in order to create the landslide risk map The final map indicates that medium, high and very high landslide risk zones are distributed in the Northwest and Northeast areas of Pac Nam including six communes: Nhan Mon, Bang Thanh, Cong Bang, Giao Hieu and Boc Bo The total area of high, very high and medium landslide areas accounts for about 57% of Pac Nam and the area of the medium risk of landslide regions is the largest compared to the remaining areas with about 40% of the district area The low risk area for landslides accounts for 43% of Pac Nam area, completely distributed in the Southeast and Southwest of this district in five communes: Co Linh, Xuan La, Cao Thang, Nghien Loan and Cao Tan i Keywords Geographic Information System, Landslide, Pac Nam Number of pages 55 Date of submission 23/09/2019 ii ACKNOWLEDGEMENT Approved by the Advanced Education Program – Thai Nguyen University of Agriculture and Forestry, I have successfully conducted the research: ―Application of remote sensing and GIS on landslide risk in Pac Nam district‖ First and foremost, I would like to thank my research supervisor, Msc Nguyen Van Hieu – director of ―GeoInformatics Research Center‖ and Mr Mui Minh Tung, who helped me a lot during the internship time Without the assistance and dedicated involvement in every step throughout the process, this research would have never been accomplished I also would like to show gratitude to the staff members of GIRC, who helped and supported me to accomplish my research In addition, I would like to thank my family and my friends by always staying by my side, encourage and help me in learning and researching Thai Nguyen, September 14, 2019 Student Nguyen Kieu Anh iii TABLE OF CONTENT DOCUMENTATION PAGE WITH ABSTRACT i ACKNOWLEDGEMENT iii TABLE OF CONTENT iv List of Figures List of Tables List of Abbreviations PART I INTRODUCTION 1.1 Research rationale 1.2 Research objectives 1.3 Research questions 1.4 Limitations PART II LITERATURE REVIEW 2.1 Theoretical basis 2.1.1 Landslide definition 2.2.2 Application of GIS on landslide analysis in Vietnam 12 PART III METHODS 14 3.1 Material 14 3.2 Methods 14 3.2.1 Data collection and analysis 14 3.2.2 Inheritance method 19 3.2.3 Multi-criteria analysis (MCA) method 19 3.2.4 Map editing method 21 PART IV RESULTS 23 iv 4.1 Natural and socioeconomic condition assessment in Pac Nam district, Bac Kan province 23 4.1.1 Natural condition 23 4.1.2 Social and economic conditions 25 4.2 Calculating the weight number for landslide estimation 27 4.3 Landslide risk assessment 29 4.4 Building the landslide risk map in Pac Nam district, Bac Kan province 30 4.4.1 Impact of terrain slope on landslide: 30 4.4.2 Impact of traffic on landslide 32 4.4.3 Impact of geological fault on landslide 34 4.4.4 Impact of land use on landslide: 36 4.4.5 Impact of rainfall on landslide 37 4.4.6 Impact of soil types on landslide 39 4.4.7 Mapping landslide risk in Pac Nam district 42 PART V DISCUSSION AND CONCLUSION 44 5.1 Consequences of landslide 44 5.2 Main reasons of landslide in Pac Nam 45 5.3 Landslide preventions 46 REFERENCES 48 v LIST OF FIGURES Figure 3.1 The photo frame picture 21 Figure 4.1 The administrative map of Pac Nam district, Bac Kan province 23 Figure 4.2 The slope map of Pac Nam district 30 Figure 4.3 The traffic map of Pac Nam district 32 Figure 4.4 The geological fault in Pac Nam district 34 Figure 4.5 The land cover map of Pac Nam district 37 Figure 4.6 The rainfall map of Pac Nam district 39 Figure 4.7 The soil types map of Pac Nam district 41 Figure 4.8 The landslide risk map in Pac Nam district, Bac Kan province 42 LIST OF TABLES Table 4.1 The weight number estimation 28 LIST OF ABBREVIATIONS CAD Computer-aided design DMBS Database Management System GIS Geographic information system GPS Global Positioning System PDA Personal digital assistant PART I INTRODUCTION 1.1 Research rationale Bac Kan is located in a northern mountainous region of Vietnam Most of Bac Kan’s surface are mountains and hills, accompanied by a complicated network of streams and rivers Due to this rugged and forested topography, the development of water resources has been limited resulting in exploitation of Bac Kan’s forest resources; this has caused degradation of the forests The climatic condition of the province is typically tropical monsoonal, the rainy season is from May to October accounting for about 88-90% of the annual rainfall and dry season lasts months between November and April leading to water shortage conditions during these months With the topography of high steep hills and mountains, Bac Kan always has the risk of land and stone landslides, seriously affecting local living conditions, especially when the leveling of houses is still arbitrary The province has about 300 spots with more than 2,000 households located in high risk of landslides, while the rainy season is still long Most families living in this area are not safe due to insufficient investment in infrastructure and high ta-luy roofs, causing potential risk for landslides The topographical characteristics of Pac Nam are gradually rising from the Southeast to the Northwest, created by large mountain ranges that have the direction of Southeast - Northwest The district has three main stream branches, one of the watersheds of the Nang River The terrain is quite complex but can be divided into large regions: High and low areas The highlands have an average height of over 800 m or more, accounting for about 60% of the whole district area This region is sparsely populated, has potentials for land, forestry and Geological fault map represents classifications of road to specific faults Based on the information, it is possible to divide Pac Nam into the following classes: The area of the distance of roads to the fault ranges from to 0.25 km, the area of the distance from roads to fault of 0.25 km to 0.5 km and the remaining area has distance of roads to fault> 0.5km The activity of the fault zones is one of the key factors in generating landslides For Pac Nam district, there are fault zones in which long fault zones run from the north to the south of the district and short fault zone belongs to Khuoi Hen, Khuoi Un and Khau Tau villages However, the fault activity here does not affect much to the landslide, most landslides are not distributed in areas where the active fault zone cuts through, the fault zones only cause landslides in communes: An Thang, Giao Hieu and Co Linh At first glance, regarding to the landslide points in the geological faults areas in Pac Nam district, it is notice that the landslide activity occur most in the area with the geological faults >0.5km However with the area of 47613.6 ha, which is the biggest area among the surveyed areas, sliding density in this area is just 0.0012, scoring point On the contrary, the region of 0-0.25km of geological fault, where having landslide points, is the place has the highest sliding density (0.0026), scoring points The area with 0.25-0.5km of geological faults has the area of 2649.2 ranked third with lowest sliding points (5 points) but the score of landslide density in this area is still higher than geological faults area of >0.5km (5 points) There is a close relationship between the fault and the land slide 35 4.4.4 Impact of land use on landslide: Regarding to sliding activities in the study area, land cover map is built on the basis of the provincial land use map Types of land cover are classified into six main classes: residential areas, water surfaces, agricultural land, forests, sparse forests and other lands In terms of landslide density, it is witnessed the largest figure in residential area, followed by water surface and sparse forest with the same figure (0.002), agricultural land, other lands and forest ranked fourth, fifth and last, respectively Forest in Pac Nam has the largest area with 27934.47 ha, it is also where landslide occurring the most (30 landslide points) but the score of density landslide here is just It is understandable because Pac Nam is a mountainous district, the forest area here is covered with rich vegetation The place which is assessed as a highest landslide risk area is residential area even though the area of this place is just rank 5th as compared with the remaining regions There are landslide points occurring in this place with sliding density is 0.007 The reason is that local residents are just focus on reconstruct house, farm,… and not pay attention to develop planting tree to prevent soil erosion and landslide Agricultural land and other lands is assessed point as forest are points of sliding density of sparse forest and water surface The exploitation of primary forest and protection forest; exploiting the property, encroaching on the stream bed to build works, houses, roads are important factors in creating mountains, landslides and flash floods Building reservoirs (in spontaneous ways) and hydroelectric dams lead to create risks of dam failure causing artificial flash floods 36 Figure 4.5 The land cover map of Pac Nam district 4.4.5 Impact of rainfall on landslide The rainfall map of Pac Nam district illustrates precipitation and sliding points occurring in Pac Nam The rainfall map is divided into layers: below 37 2000 mm/year and over 2000 mm/year Rain plays a big role in the process of landslide Heavy rain triggered flash floods and landslides The typical weather patterns cause heavy rain, wide rain to create the convergence of winds, significantly increasing rainfall and the intensity of rain causing flash floods Not only heavy rain in a short time can cause flash floods, landslides, but if the rain lasts for many days to saturate the soil layer, no longer able to store water and cohesion, just a rain will entrain trees, rocks and also likely to cause flash floods, landslides As you can see from the map, the areas with heavy rainfall are also where landslides occur with high frequency in the rainy season The relationship between the landslides with rainfall shows that the density of landslides increases with rainfall The rainfall> 2000mm /year is the cause of 45 landslide points in total of 70 landslide points in the district With a not too high sliding density but occurring in an area not too large, the level of slip with this rainfall is given point For rainfall of 0-2000mm /year, causing 25 landslide points on a total area of 24847.8 ha, is the score for landslides in these rainfall areas of the district The rainfall of 0-2000mm / year is located in the Northern region of surveyed district while the Southern area of the district mainly has precipitation of >2000mm/year, just 2% of this region have precipitation of 0-2000mm/year 38 Figure 4.6 The rainfall map of Pac Nam district 4.4.6 Impact of soil types on landslide In the soil map of Pac Nam district, there are data of soil type which are divided into types: feralit soil, red humus soil, valley soil and alluvial soil and data of landslide points of this district The characteristics of soil types and the 39 management and use of land greatly affect the erosion and landslides of Pac Nam district Some types of soil such as feralit soil and alluvial soil are both use for agricultural purposes to provide residents with adequate food source thanks to nutrients in each two types of soil Using benefits of soil also be a mitigation factor of minimize appearance of landslide By contrast, people cannot plan tree in valley soil, it makes landslide active strongly in regions owning valley soil As you can see from the Table 1, the analysis results in the key zone show the highest number of landslide density is in valley soil with the density is 0.07 Valley soil has the smallest area as compared with the remaining region but having landslide points in a narrow place-the reason makes score of landslide activity is Landslide activity in valley soil is followed by the number of landslide density in feralit soil which is assessed points Feralit soil owns the largest area among the surveyed areas however landslide density here is just 0.0012 is the points for both alluvial soil and red humus soil 0.0007 is the landslide density of red humus soil while the landslide density of alluvial soil is 0.0011 40 Figure 4.7 The soil types map of Pac Nam district 41 4.4.7 Mapping landslide risk in Pac Nam district Figure 4.8 The landslide risk map in Pac Nam district, Bac Kan province Establishment of a landslide risk map is based on a table of soil sentivity The level of landslide or landslide risk increases with the index of landslide, which means that the risk of landslide is higher when the index is higher and vice versa Typically assessing a risk is categorized into three levels (high, moderate and low) or more specifically with levels (very high, high, moderate and low) The assessment with the levels applied here for the risk of landslide is reasonable and detailed enough to reflect the overall picture of landslide in the 42 area The values for levels are as follows: low (1-3), moderate (3-5), high (5-7), very high (7-9) According to this classification, medium, high and very high risk areas are distributed in the Northwest and Northeast areas of the district including six communes: Nhan Mon, Bang Thanh, Cong Bang, Giao Hieu and Boc Bo In addition, the average risk of landslide occurs in the road system in the southern area of the district Therefore, the total area of high, very high and average landslide areas accounts for about 57% of the district area and the area of the moderate risk of landslide regions is the largest compared to the remaining areas with about 40% of the district area The low risk area for landslides accounts for 43% of Pac Nam area, completely distributed in the Southeast and Southwest of this district in five communes: Co Linh, Xuan La, Cao Thang, Nghien Loan and Cao Tan Compared to the rest of the regions, the area where the low level of landslide does not occur on the roads, the roads in this area have the average level of landslides The high, medium and high risk areas for landslides are mainly located in the district roads where rainfall is in the range of 1800-2000mm / year and there are many geological fault activities in the area While the area's rainfall is assessed as being at risk of low landslides with rainfall