Tutorials: ArcGIS - Tutorial 3

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Tutorial 3: Apply your skills for a geohazard mapping of the Pamir region in Tajikistan. 

 

 OBJECTIVE:

The non-profit Central Asia Institute is looking for suitable locations for building their next round of new schools in the Pamir region of Tajikistan. They have recently received a list of potential locations for schools from the Tajik Ministry of Education in Dushanbe. These locations are:

  • Vanj (38o22’2” N, 71o27’1” E)
  • Murghab (38o10’45” N, 73o58’41” E)
  • Vankala (37o43’14” N, 72o16’58” E)
  • Langar (37o3’4” N, 72o40’14” E)

To assess the suitability of these sites, the institute has hired you as an independent consultant. The institute is particularly worried about the occurrence of geohazards at/near each site. These include earthquakes, mass wasting events, snow avalanches, and floods including glacial lake outburst floods.

To help the institute make an informed decision concerning the construction of schools at the proposed sites, you will create a series of maps that can be used in hazard assessment. To create these maps and a final assessment report, you will rely on the skills you learned in Part 1 and 2 of this exercise. You are also encouraged to use Google Earth, the online Quaternary fault database for Central Asia (https://esdynamics.geo.uni-tuebingen.de/faults/) and peer-reviewed scientific literature to address the following questions for each site:

  1. How far is each site from the nearest active fault(s)?
  2. Is there a fault(s) near each site that is capable of producing M ≥ 5 earthquakes?
  3. What is the level of seismicity at each site? Is there a record of past earthquakes? What size/depth earthquakes are expected in the area surrounding each site?
  4. May the expected shaking in response to an earthquake be higher at each site?
  5. Are there areas with hillslope angles near failure and at risk for future landslides at each site? Is there evidence for past landslides?
  6. Are the sites at a high risk for snow avalanches?
  7. Is there a possibility of future ice-dammed lake formation and outbursts at/near each site?
  8. Are the sites likely to be affected by flood events?

Your report should satisfy these requirements:

  • Maximum 5 pages of text, double-space (not including title page, table of contents, figures, references, and an appendix)
  • Attach your answers and maps from Part 3a as an appendix to your final report.
  • See guidelines listed at the end of this document (Part 3b) for your report structure.

 

DATA

You can download all required files by clicking on them:

Other datasets you will use in this exercise:

  • Quaternary fault: Your fault_line feature class from the Part 2 of this exercise

 

Remember:

  • Bring a USB flash drive to class, create a folder and name it ArcGIS_Exercise3. Save all files related to this exercise to your USB drive.
  • Part 1 and 2 – bring your ArcMap files from part 1 and 2 of this exercise.
  • Relative paths- set the .mxd’s data source to relative paths.
  • Save your ArcMap (.mxd file) regularly.

 

 

PART 3a

A Surface Analysis - Launch ArcMap and add your DEM file: nasa_srtm_v3.0_3arcsec_pamir.tif. Add the x,y coordinate data (location of the school sites) as a layer to your map. Check each site location using Google Earth to make sure they are plotted correctly in Arc. In the attribute table for this layer, make sure to include the name for each site (e.g., Vanj). For more information, see the Part 1 of this exercise (section D: adding point data). After adding school sites to your map, refer to the Part 1 of this exercise (section B: surface analysis) in which you calculated these parameters:

  • Hillshade
  • Slope
  • Aspect
  • Curvature

Which of these parameters (or combination of them) may help you with assessing hazards at each site? Check the box next to those relevant to this exercise, and derive them from your DEM in ArcMap. Take some time to investigate each data layer. Display the layers in a way that will help you identify potential geologic hazards in the area.

Answer the following questions for each site:

  1. In what areas (if any) are the hillslope angles near failure and at risk for future landslides?
  2. Is there evidence for past landslides?
  3. What areas (if any) are at a high risk for snow avalanches?
  4. Take a look at the landslide hazard distribution map developed by World Health Organization in 2010 for Tajikistan. Is this map in agreement with your observations from above? Why or why not?

 

B. Hydrologic Analysis - Refer to the Part 1 of this exercise (section C: hydrologic terrain analysis) in which you calculated the following:

  • Flow Direction
  • Flow Accumulation
  • Stream Network
  • Stream Order (Strahler)

Which of these calculations (or combination of them) may help you with assessing hazards at each site? Check the box next to those relevant to this exercise, and derive them from your DEM in ArcMap. Take some time to investigate each data layer. Display the layers in a way that will help you identify potential geologic hazards in the area. Answer the following questions for each site:

  1. Are there areas near the site where flooding is more likely to be significant?
  2. Look at the flood hazard map developed by World Health Organization in 2010 for the country of Tajikistan. Is this map in agreement with your observations from above? Why or why not?

 

C. Earthquake Data Analysis – Refer to the Part 2 of this exercise (section B: digitizing and adding data) in which you created the following data layer:

  • Fault_line (feature class) and related Attribute Table

Load the fault lines into your ArcMap project. Then refer to Part 1 of this exercise (section D: adding point data) to add the earthquake files (GFZ_aboveM5 and GFZ_belowM5) to your current ArcMap project. Show earthquakes <70 km in depth in orange circles (these are shallow, crustal earthquakes) and those >70 km in blue (these are intermediate-deep earthquakes). Increase the size of your symbol for earthquakes larger than magnitude 5. Keep in mind that your earthquake dataset covers a two-year period (2008-2010).

Optional: For a longer earthquake coverage period (1900-2014), please go to https://esdynamics.geo.uni-tuebingen.de/faults/ and check the box next to “Show Earthquakes” in the interactive map. Then select events from the ANSS ComCat.

Display your DEM together with the earthquake and fault data and use these layers to answer the following questions for each site:  

  1. Are there earthquakes near your site? If so, describe their size and depth.
  2. How far is your site from the nearest active fault(s)? Describe the fault(s) (e.g., name, seismic history if known, and slip rates if available). Is the fault(s) capable of producing M ≥ 5 earthquakes?
  3. Is there a possibility of earthquake-induced mass wasting at or near each site? (take a look at maps from section A of this exercise).

Deselect the earthquake and fault layers in the Table of Content in ArcMap. Now load the global_vs30.tif file. This shows the average shear-wave velocity down to 30 meters across the area. It gives an indication of whether the expected ground shaking in response to an earthquake may be higher. At a bedrock site (high shear-wave velocity), there will be little amplification of seismic waves. In a sedimentary basin (low shear-wave velocity), one might expect intense amplification. Change the display setting so that areas with low shear velocity are shown in red/orange and areas with high shear velocity are shown in blue/green. Take a look at your result. Investigate and identify locations where one may expect higher shaking in your study area.

  1. May the expected shaking in response to an earthquake be higher at/near the sites?

Turn in: Include your maps and answers to questions from above sections as an Appendix to your assessment report in the final PDF file. Make sure your maps show title, legend, scale bar, grids, and your name. To create and save your maps, see the steps shown in section A1-b in the Part 1 of this exercise.

Part 3b

 

Report Guidelines

 

The following section explains the general structure and content that should be included in your final assessment report. Your report should be maximum 5 pages in length (not including title page, table of contents, references, figures and the appendix). Your report should contain the following sections:

 

Title Page

Table of Contents

Introduction

Study area

Methods

Results

Discussion

Recommendations

References 

Appendix

 

Each section is described below.

Title Page – The title page should show the report’s title, your name, and submission date (month/year). Remember a good title predicts content and reflects the tone of the report. 

 

Table of Contents – In the Table of Contents, include the names of all the headings and subheadings in the main text and relevant page numbers. Include a list of all figures and appendices with relevant page numbers.

 

1. Introduction

In this section, include the overall purpose of your assessment report and its significance. Use the subheadings shown below and add new ones as you see fit.

1.1 Objectives (problem statement)

1.2 Significance of the Problem

 

2. Study area

In this section, describe the study area (Pamir region of Tajikistan). For the Pamir region (or alternatively for each school site) provide general information on the type and abundance of geohazards. You may include information on the type and extend of damage caused by previous geohazards in the region (and/or near each site). Cite references to published literature to support your statements. Include relevant figures (e.g., study locations) in this section. You may consider creating subheadings like the one shown below for each site:

 

2.1 Vanj valley, Western Pamir (school site: Vanj)  

 

3. Hazard Mapping

This is your methods section. Describe your assessment process (in words or using a flow chart). Give details on input datasets (explain data types, sources, coverage periods, etc.). Describe all tools used (e.g., ArcGIS) to identify and understand the level of hazards at each site. Use subheadings like the ones shown below, and add new ones as you see fit.

3.1 Methods

3.2 Datasets

 

4. Results

Start this section with a short paragraph that explains the items presented in the subsections. This orients the readers’ brain towards what will be presented and the logic behind your organization. This section should only present observations. Interpretations should not be mixed with observations. Create subheadings like the ones shown below for each observation. Include figures (and captions) to support your observations.

 

4.1 Surface Observations

4.1.1 Vanj Site in Western Pamir

...

4.2 Hydrologic Observations

4.2.1 Vanj Site in Western Pamir

...

4.3 Earthquake Observations

4.3.1 Vanj Site in Western Pamir 

…

 

5. Discussion

In this section, you present your interpretation of the results. For example, explain how your observations of slope distribution (from 4.1 for example) near a school site relate to potential hazards at the site. Create subheadings like the ones shown below for each site. Include figures (and captions) to support your interpretations.

4.1 Potential hazards at Vanj school site

…

 

5. Recommendations

Conclude the assessment report by proposing recommendations for school construction at each site. Your recommendations should be based on your data analysis and interpretations. It may be useful to create a bullet list of recommendations relevant to each school site. Explain any shortcoming in your assessment and your recommendations for including other datasets for a more comprehensive hazard assessment study in the region.

 

6. References - Ensure that every reference cited in the report is also present in the reference list (and vice versa). References can be in any style or format as long as the style is consistent.

 

What To Hand In:  

  • Hand in your final assessment report (Part 3b) as one PDF file (not Word) through the Illias website. In your final PDF file, also include your work from Part 3a as an appendix.
  • To add files to Word or Libre office document before making the PDF file we suggest you: export and save the relevant maps as tiff files from the ArcMap window (go to File -> Export Map). Then insert the tiff files into a MS Word document and save the document as PDF.
  • For each figure you put in the final PDF file, add well written figure caption. The first sentence of the caption should say in general terms what is plotted. The following sentence should describe how the analysis was done, and what the primary result is that the reader should see in the plot. Your figure/map must show title, legend, scale bar, grids, and your name.
  • Hand in your final PDF file via the Ilias website.
  • No late assignments will be accepted (we’re not kidding).