Hazard modeling
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This document summarizes landslide hazard modeling conducted in Dewal, Pakistan. The study analyzed elevation data from 2008 and 2012 to identify areas prone to landslides. Shapefiles and rasters were created in ArcGIS and profiles/graphs were generated. Comparisons found that higher elevations saw more excavation from 2008 to 2012, making them more landslide-prone, while lower areas remained stable. Issues arose in accurately generating rasters in ArcGIS and profiles/graphs in AutoCAD. Overall, the 2012 study area near high elevations was determined to be at greater risk of landslides.
Hazard modeling
- 1. Landslide Hazard Modeling Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 1
- 2. Landslide Hazard Modeling Table of Contents 1. Chapter 01 04 a. Introduction to Hazard 04 b. Types of Hazards 04 c. Hazard Identification 04 d. Hazard Modeling 05 i. Steps for Hazard Modeling 05 ii. Reasons for Hazard Modeling 05 2. Chapter 02 07 a. Objective 07 b. Study Area 07 c. Data Sources 07 d. Data Format 07 e. Software 07 f. Methodology 07 g. Results 08 h. Comparisons 13 3. Issues and Problems 16 4. Conclusions 17 5. Reference 18 Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 2
- 3. Landslide Hazard Modeling Figures List Figure 1: Steps to conduct Hazard Modeling 06 Figure 2: Shape file of Dewal_2008 09 Figure 3: Shape file of Dewal_2012 09 Figure 4: Raster of Dewal_2008 10 Figure 5: Raster of Dewal_2012 10 Figure 6: Profile Graph_2008 11 Figure 7: Profile Graph_2012 11 Figure 8: Results in Arc GIS 12 Figure 9: Results in Auto-cad 13 Figure 9: Shape files Comparison 14 Figure 10: Raster Comparison 15 Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 3
- 4. Landslide Hazard Modeling Chapter 01 Bbefore dealing with hazard modeling, firstly understand the true meaning of hazard. What is actually a hazard is? Hazard is defined as: “A hazard is a source of potential danger or adverse conditions.” Types of Hazards The type of hazard has been classified into two major categories: 1. Natural 2. Man Made Natural Hazards: It includes: Floods, Hurricane, Earthquake, Tornadoes, Wildfires, Landslides. Viruses, Weapons of mass destructions, Chemical Explosions, Chemical and biological agent, Terrorism. Man Made Hazards: It includes: split, Hazard Identification The most important task in hazard modeling is to identify the areas that are: 1. The sources of hazards, and 2. More affected by the hazards. Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 4
- 5. Landslide Hazard Modeling According to FEMA (Federal Emergency Management Agency), “Hazard identification is a process of defining and describing a hazard, including its physical characteristics, magnitude and severity, probability and frequency, causative factors, and locations/areas affected.” (Schwab et al. 1998) Consider the Effects of Hazard Before Disaster Happens It is important to keep eye on the cause of hazards before the disaster happens from previously tracked or recorded data. The most meaningful steps are taken by the state and local level officials that have a personal contact with the community. 1. It cost too much to address the effects after the disaster, 2. One can prevent some of the damage from hazard if one knows where and how the natural phenomenon occurs, 3. Most probably federal aid after disaster does not cover all portions and costs effectively. Hazard Modeling During hazard modeling, one uses the current knowledge and pre-existing structures to identify the areas that are prone to disasters. In additions to that, the community growth plan or flat map super imposed with the hazard map will help us to identify the areas that are more vulnerable to natural hazards. Steps to Conduct Hazard Analysis: Few of the steps are mentioned below used to conduct the hazard analysis: 1. Analyze each potential event from beginning to end. 2. Estimate the probability of the events occurring. 3. Analyze potential human effect on each disaster. (e.g. death or injury) 4. Assess the potential property impact on losses and damages. Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 5
- 6. Landslide Hazard Modeling Fig 1: Steps to conduct Hazard Modeling Reasons for Hazard Analysis: The few of the reasons for hazard analysis are as follows: 1. Identify the areas that are most at risk, 2. Identify the risks for built/ natural environment, 3. Assess capability to response/recover, 4. Provide data for economic analysis, 5. Provide base for decisions, 6. Helps to apply cost-benefit approach. Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 6
- 7. Landslide Hazard Modeling Chapter 02 Objective The objective is to find out the areas that are more susceptible to hazards due to its topological structure. By making comparison of data of different times, we can estimate the cut/fill area. Study Area The study area is Dewal, Murree, Pakistan located at 33°59'0N, 73°28'0E with an altitude of 1712 meters and UTM zone 43N. It is a Union Council of Murree Tehsil (a sub division), of Rawalpindi District in the Punjab province of Pakistan. Data Sources The data is acquired by the help of the total stations. Data Format The data is in Excel format with elevation values of Dewal side of the year 2008 and 2012. Software The software used is: 1. Arc GIS 9.3 2. Auto cad 2007 & 2010 Methodology The performed step by step procedure is as follows: STEP: 01 Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 7
- 8. Landslide Hazard Modeling 1. Open Arc Map 9.3. 2. Add Excel File. 3. Display XY Data. 4. Export the shape file. 5. Create a shape file of Polygon. And edit the boundary of the exported Points shape file. 6. Create Raster: a. Spatial Analyst Tool – Interpolation – Topo to Raster b. Add Shape file of points and polygon. c. For Point Shape file: Use “Point Elevation” and “ZC” under filed tab. d. For Polygon Shape file: Use “Boundary” under filed tab. e. Use “No Contour” under the field of Drainage. f. Click OK. 7. By using 3D Analyst: pick “Interpolate Line” and draw a line over the raster. 8. By using 3D Analyst: pick “Profile Graph” and calculate the Vertical Profile. 9. By Right clicking the graph, Export the graph to Data type Excel. 10. Repeat the procedure for both year data. 11. Create Map Layout for each data. STEP: 02 1. Open Auto cad. 2. In Command Line, type: “pl” and Enter. 3. From the Exported Excel file of Profile Graph, Copy the XY data and Paste in the Command line, and press Enter. 4. Press Esc to cancel. 5. Decorate the graph for Save and Display. Results The results are shown in the form of Maps as follows: 1. Exported shape file of year 2008. Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 8
- 9. Landslide Hazard Modeling Fig 2: Shapfile_2008 2. Exported shape file of year 2012. Fig 3: Shapefile_2012 Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 9
- 10. Landslide Hazard Modeling 3. Raster date of year 2008. Fig 4: Raster Data_2008 4. Raster data of year 2012. (Fig 5: Raster Data_2012) Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 10
- 11. Landslide Hazard Modeling 5. By using Profile Graph, calculate the Vertical Profile of the Dewal area of year 2008. Fig 6: Vertical Profile_2008 6. By using Profile Graph, calculate the Vertical Profile of the Dewal area of year 2012. Fig 7: Vertical Profile_2012 Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 11
- 12. Landslide Hazard Modeling 7. The final output of cut/fill result in the arc GIS is as follows: (Fig 8: Results in Arc GIS) Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 12
- 13. Landslide Hazard Modeling 8. And the same output in the Auto-cad is as follows: (Fig 9: Results in Cad) Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 13
- 14. Landslide Hazard Modeling Comparisons By comparing the results, it is clear that overall elevation increases from the year 2008 to 2012. Following comparison map is showing the area of Dewal and surveyed points for the year 2008 and 2012, up and down, respectively. (Fig 10: Shape files Comparison) In the survey of 2012, two prominent points have been captured on upper and lower side, showing decrement and increment in elevation. Following showing map of DEMs is showing the accuracy of above mentioned results. Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 14
- 15. Landslide Hazard Modeling Fig 11: Raster Comparison Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 15
- 16. Landslide Hazard Modeling Issues and Problems This is going to be the most important part of the assignment, as this makes its harder and time consuming. 1. First, the arc GIS is not always generating the raster accurately. Sometimes, it shows that results of that data which have been done previously. 2. Secondly, in Auto-cad, I am completely unable to generate graph. But, don‟t know the error is. I have tried so many ways, defined as follows: a. Firstly, type „pl‟ in Command line, and paste the XY values. NO result. b. Then tried by, typing „MULTIPOINT‟ in Command line, and paste the XY values. NO result. c. At the end, copy XY values in notepad. Types „LINE‟ on the start, followed by values. And save it with „Name.scr‟. This will generate „Auto-cad Script‟ file. Now open the Cad, in the Tool bar, Select „Run Script‟ and navigate to the saved file with extension „.scr‟. Still NO result. Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 16
- 17. Landslide Hazard Modeling Conclusions By performing the whole practical, and comparing the results from different sources and ways. It is cleared that in the year 2012, the study area, near the high elevations, is more prone to excavation. There exists a much deeper but a gentle cut in the higher elevated areas. While the lower areas were generally like a regular hilly area. While in case of year 2008, the area was having steep dip at the elevated portion as compared to the lower portion. Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) Page 17
- 18. Landslide Hazard Modeling Reference 1. http//: training.fema.gov E IWeb E ICourses E Atiqa Ijaz Khan Institute of Geology (Session: 2013-15) C Unit .pdf Page 18