Report Developing a course component on disaster management By Chira Prangkio Tawee Chaipimonplin Department of Geography, Faculty of Social Sciences, Chiang Mai University Thailand Presented at Indian Institute of Remote Sensing IIRS, Dehradun, India on March 2004
CONTENTS Summary 1 Introduction 2 Course detail 3 Case Study 6 Index 11
Summary Department of Geography, Faculty of Social Sciences, Chiang Mai University has developed a new subject, which is undergraduate level, named Natural Hazard and Risk Assessment. This subject runs for one semester and earns 3 credits point. Part of this subject, GIS and remote sensing technique will be used as tools for natural hazard mapping. In addition, ILWIS software also used for case study. Methodology of case study is shown below. Study the causes of landslide Study area Physical factors of landslide Analysis risky area of landslide by using conditions Located villages in area of landslide risky 1
Introduction Under the program, which is developing a course component on disaster management, is hosted with three partners from Thailand (Asian Disaster Preparedness Center, ADPC), The Netherlands (International Institute for Geo-information Science and Earth Observation, ITC) and France (Ecole Nationale des Sceinces Géographiques, ENSG). The program aims to build capacity on modern disaster mitigation tools and targeted at reducing disaster vulnerability of urban regions in Asia. It also provides supporting to the institutionalization of academic courses on disaster mitigation in existing urban planning curricula at university level. Department of Geography, Faculty of Social Sciences, Chiang Mai University has structured a new course, which is natural hazard and risk Assessment, is part of undergraduate program in Geography, also developed a case study. Moreover, GIS and remote sensing are tools in disaster management and ILWIS software will be used for GIS and image processing as a course material. 2
Course Detail Course Name: Natural Hazard and Risk Assessment Objectives: Understand the concept of hazard assessment Understand and consider in terms of human adjustment to natural disasters. Understand and be able to use geo-information technology in natural hazard assessment and risk assessment Course description: Focuses on the natural aspect of hazards: the dynamic relationship between human and environment, examining impacts, human response, planning and adjustment. Preventing and mitigate natural hazards at regional and national levels. Providing knowledge of remote sensing and GIS application for hazard mapping; floods, landslides, topical cyclones, forest fires, earthquakes and droughts. Course information: 3 Credits 1 semester 15 weeks 3 hours lecture or 2 hours lecture plus 3 hours practical per week Undergraduate level Mark ratio (20:40:40)(case study : mid-term exam : final exam) 3
Course contents hours of lecture/practical 1. Introduction to natural hazard and risk assessment 3/- 1.1. History and background 1.2. Definition and basic concepts 1.3. The global problem 2. The impact of natural hazard 9/- 2.1. Atmospheric and hydrological hazards 2.2. Disasters and the land surface 2.3. The geophysical agents 2.4. Human impact and response 3. Concept of disaster assessment 3/- 3.1. Identify the main controlling factor for natural hazard 4. Planning and preventing natural hazard 6/- 4.1. Impact of natural hazard 4.2. The hazard reduction process 4.3. The logistics of planning and emergency action 5. Introduction to GIS, remote sensing and data requirement 2/3 6. Applied GIS and remote sensing for hazard assessment 2/3 7. Introduction to ILWIS 6/9 7.1. Concept and introduction of ILWIS 7.2. Spatial data management 7.3. Image Processing 7.4. Spatial data analysis 8. Case study 6/9 8.1. Impacts of disasters on developing countries 8.2. Case study Total 37/24 4
Schedule Week Topic Practical 1 Introduction to natural hazard and risk assessment No 2 Impact of natural hazard No 3 Impact of natural hazard No 4 Impact of natural hazard No 5 Concept of disaster assessment No 6 Planning and preventing natural hazard No 7 Planning and preventing natural hazard No 8 Introduction to GIS, remote sensing and data Yes requirement 9 Applied GIS and remote sensing for disaster Yes assessment 10 Introduction to ILWIS Yes 11 Introduction to ILWIS Yes 12 Introduction to ILWIS Yes 13 Case study Yes 14 Case study Yes 15 Case study Yes 5
Case study Landslide hazard and risk assessment for cities village Introduction Phayao is a mountainous province of Northern Thailand. The topography consists of 60 percent of mountain area with 500-1800 meters of altitude and 40 percent of narrow river basin with 300-500 meters above mean sea level. The climate of Phayao is influenced by Monsoon climate with the average 1400 millimeter of rainfall in southwest monsoon (May- September). From October to April is dry northeast monsoon climate. It is heavier rain in the highland. Tropical storm from South China Sea is also sometimes reaches the area and causes the heavy rain. Most of the highland covers with the forest but hill tribe people have used some areas for shifting cultivation. Major agricultural land in the river basins is used for rice production by the low land people. Landslide is the common phenomena in the highland of Phayao which happens during the rainy season especially when it is heavy rain from tropical storm. The disaster from landslide depends on the location and size of landslide. When the huge landslide occurs in the highland, the debris will run down along the streams to the lowland river basins. This causes the lost of agriculture area, animal life and human life. The study of the landslide risk area in the province is necessary to prepare the disaster prevention. In October 2002 it was heavy landslide at the highland of small watershed MaeTum, western part of the province. Ten spots of landslide in the 6
watershed destroyed the rice fields and cattle along the stream. Fortunately there is the dam and reservoir to stop the debris to bury the down stream villages. This cause is used for this study as the criteria of the landslide in the whole province. Objectives Built up more knowledge of application GIS and Remote Sensing for hazard assessment Zoning the Risk area for landslide hazard in the rural area Be part of the local Administrative program of public awareness, also preparedness, evacuation and/or relocation of communities Methodology Zoning risky area, physical data are required. Those data are slope, height, geology, land used, rainfall, drainage and village location. Moreover, all data can be imported from AerView sharp file. There are four physical factors; slope, height, geology and land used will be used for analysis as overlay operation. Before operate overlay layer, each factor need to be add a value that contributes landslide. Decision making the value for each factor can be done from analysis with the study area that has occurred landslide on October 2001. Value 1 point represents the factors that could lead to landslide and value 0 could not. (See table below) 7
Factor Description Value Height Higher than 620 meter 1 Height less than 620 meter 0 Slope Slope more than 27% 1 Geology Land used Slope less than 27% 0 Gravel/conglomerate, sand/sandstone, 1 shale Others 0 Hill ever green forest 1 Others 0 Adding four physical factors with value can form landslide zone, so the landslide zone map can be seen from value 0-4. Then, the level of risky landslide zone can be classified to non-risky area (0-1), less risky area (2) and high risky area (3-4). The next step is located which villages are in high risky area by adding more layers that are village location and drainage. 8
Flow chart Data preparation Import data ILWIS data format Physical data Slope Height Geology Land used Rain fall Drainage Villages location Analysis Study area Study the physical factors that cause of landslide Physical factors lead to landslide Analysis the physical factors in risky area of landslide Landslide hazard zone map Villages that are located in high risky landslide zone 9
Result The result map as shown figure 1. red color is shown high risky area (number 3 and 4), green is shown less risky area (number 2) and nonrisky area is represented in gray (number 0 and 1). Moreover, each black point represent a village that is located in risky zone. Figure 1. Map result 10
Index
Case Study Landslide hazard and risk assessment for cities village By Department of Geography, Faculty of Social Science, Chiang Mai University, Thailand 50200 Summary In this exercise, slop, forest, geology and height are used to calculate risk landslide hazard factor maps. Study area is applied to a data set of Phayao province. 1. Convert Vector map to Raster map. 2. Chang attribute raster map. 3. Cross operation -Study area/forest -Study area/geology -Study area/height -Study area/slop 4. Reclassification -Giving a value to pixel (1,0) 5. Overlay operation -Map calculation -Forest + Geology + Height + Slop Landslide Hazard Zone Map Add drainage, rain fall and village layer. Villages that are located in risk landslide hazard zone. 1
Getting started Double-click the ILWIS program icon in the ILWIS program group. Change the working drive and the working directory until you are in the directory where the data are stored. Now you are ready to start the exercises of this case study. 1. Preparation of the data Before you start with overlay operation, you need to convert polygon map, point map, vector map to raster map. Click Operation in the Control Menu Icon Click Rasterize, Polygon to Raster Select polygon maps, which are slop, forest, geology, height, study area, village and drains, covert to raster map. Create new geo reference from Rasterize Polygon Map window Typing geo reference name is Landslide and select Unknow for coordinate system (all raster maps will be used the same geo reference that is Landslide) Then click show. Now you have all raster maps that are ready for analysis and have same geo reference. 2
2. Changing attribute map. In this operation, you need to change attribute map. The propose of changing attribute is to group data by class of map for cross operation. 2.1. Creating Geology_ID raster map Click Operations in the Control Menu Icon Click Raster operations, Attribute Map. Select Geology as Raster map. Select Code as Attribute. Type output raster map as Geology_ID, then click show. 2.2. Creating Height_ID Click Operations in the Control Menu Icon. Click Raster operations, Attribute Map. Select Height as Raster map. Select Code as Attribute. Type output raster map as Height_ID, then click show. 3
2.3. Creating Slop_ID Click Operations in the Control Menu Icon. Click Raster operations, Attribute Map. Select Slop as Raster map. Select GridCode as Attribute. Type output raster map as Slop_ID, then click show. 3. Raster Operation-Cross In this operation, you will use Cross operation that is intersection between two raster maps. To determine risky landslide zone, we will use the study area map that have been happened in that province, is the main map for classification the factor for each map layer. Click Operation in the Control Menu Icon. Click Raster Operations and then click Cross 3.1. Cross with Study area and Forest raster map. In this operation, after cross Study area raster map with Forest raster map, you will know what types of forest those contribute for landslide hazard zone. Select Study area raster map as 1 st Map. Select Forest as 2 nd Map. Typing Output table as Forest risk. Click Show. 4
Now you know what forest types are on the study area that is the landslide hazard area has been happened from table Forest risk. Open table Forest risk. Write down numbers in Forest column (The numbers represent forest type). You will use the number for reclassification Forest map (see below). 3.2. Cross with Study area and other raster maps. For the other raster maps; Slop_ID, Geology_ID and Height_ID do the same as Forest raster map. Out put table can be named Slop risk, Geology risk and Height risk. After Cross operation, you will open for each table and write down the number that cross with study area for each factor. 5
4. Creating a value for risk and non-risk landslide zone of each factor. For creating a value for each factor you will need to create a new column for each table called Value. In Value column you need to give number to 1 or 0. Moreover, number 1 represents factor that can contribute landslide hazard and number 0 represents factor that cannot contribute landslide hazard 4.1. Creating value for Forest type. You can reclassification forest type to forest types that can contribute landslide hazard to 1 and forest type that cannot contribute landslide hazard to 0. In this case study, forest type number 3, which is Hill Evergreen Forest, is the forest that can contribute landslide hazard, so you will make this forest type value to 1 and other forest types value to 0. Therefore, you will need to create a new column that is called Value by using conditional function formula. Open table Forest. Type the following formula on the command line: Value=iff ((Forest_ID=3),1,0) then enter. Click ok in Column Properties window Now you already have new column that contains value of forest type. You will use this value for calculation. 6
4.2. Creating value for Geology. Now you will do the same thing as 3.1. In this case study, Geology code are 35 and 10 are geology types that you need to make a value to 1.Geology code 35 represents Conglomerate and Sandstone as Geology Type, also number 10 represents Conglomerate, Shale, Sandstone and Limestone. Open table Geology. Type the following formula on the command line: Value=iff ((Code=35) or (Code=10),1,0) then enter. Click ok in Column Properties window 4.3. Creating value for Height. In table Height, you will use Code column for this formula. Open table Height_pol. Type the following formula on the command line: Value=iff((Code=2),1,0) then enter. Click ok in column Properties window. 4.4. Creating value for Slop In table Slop, you will use Grid code for this formula. Open table Slop. Type the following formula on the command line: Value=iff((gridcode=1) or (gridcode=2) or (gridcode=3),1,0) then enter Click ok in column Properties window. From this section, you will have a value column that contains 1 or 0 in each table. 5. Changing attribute for raster map Before you operate overlay operation, you use the attribute table that is Value for calculate. You need to change an attribute raster map to value for all raster maps that will be used for overlay. Click Operations in the Control Menu Icon Click Raster operations, Attribute Map. Select Forest as Raster map. Select Value as Attribute. Select Value as Domain. Type output raster map as Forvalue, then click show. 7
Click Operations in the Control Menu Icon Click Raster operations, Attribute Map. Select Geology as Raster map. Select Value as Attribute. Select Value as Domain. Type output raster map as Geovalue, then click show. Click Operations in the Control Menu Icon Click Raster operations, Attribute Map. Select Height as Raster map. Select Value as Attribute. Select Value as Domain. Type output raster map as Heivalue, then click show. Click Operations in the Control Menu Icon Click Raster operations, Attribute Map. Select Slop as Raster map. Select Value as Attribute. Select Value as Domain. Type output raster map as Slopvalue, then click show. 6. Overlay operation. In this sector, you will use Map Calculation function. Many maps can be combined at the same time. Map Calculation formulae are typed on the Command line of the Main Window. Typing map calculation formula in the command line: Areafall=Forvalue+Geovalue+Heivalue+Slopvalue Then enter. Now you have map that shows value from 0-4. Value 0-1 represent area low, value 2 represent moderate and value 3-4 represent area high risky landslide. 8
7. Risk assessment After you have landslide risky zone, you need to add drainage, rainfall and village layers. Finding out which village is located in landslide zone. Open Areafall map. Click Layers at menu bar Then add layer (Village and Drainage) Now you can locate which villages are under high risky landslide zone. 9