Module 5: Damage Assessment

 Module 5: Damage Assessment

This weeks module was about how to assess damage to structures after Hurricane Sandy. We were supposed to use FEMA "standards" to get the information they might need to help with relief.

The first part was to make a map that showed the tract of Hurricane Sandy from the Atlantic Ocean to the eastern coast. We learned how to create a line from points that were create from a XY Table. The geoprocessing tool is Points to Line (Data Management Tools) and it showed the path of Hurricane Sandy. The next part of the module we needed to change the symbology of the points so they would represent the different phases of a hurricane. The way we did this was to use Creating Marker Symbols because it makes it possible to make the points into a good symbology. The way to do this is to click on the symbology tab to change the different values into the correct symbols. We were given the exact ones to select for the points but under the properties tab then go to the layers menu. Under the Appearance tab choose Font. This will give you more options to change your symbology. The image below shows the final outcome of the path of Hurricane Sandy.

The next portion of this module we needed to create a survey on the Survey123 in ArcGIS Pro Online. This is useful to learn because you are able to send this out to the public and they can help you get data after a tragic event such as a hurricane. This survey was for the damage assessment for Hurricane Sandy. You are able to make so many different questions that have to be required in order to go on with the rest of the survey. Also, another important aspect is that you can add images and the exact date/time it was taken. Lastly, the survey can have a map put in and there is a point added when they open this portion of the survey. The link is where you can look at the survey for instructional view only: https://arcg.is/1zTePH1.

In the final portion of the module was getting the images for pre-and post-Sandy, adding domains, and analyzing the data for the "FEMA" client. We were giving the images that were going to be used for this exercise but when getting your own data being able to get good imagery data is important to assess any damage. First we needed to create a Mosaic Dataset and then add the raster data to the dataset. Having both of the images on top of each other is helpful because you can keep going back and forth to see where the damage is located. Next we needed to add domains so we can have it for attribute values for the points that we are going to use to assess the damage from Hurricane Sandy. You want to right click you geodatabase and choose Domains. It will open up a table similar to an attribute table. We put in the domains we wanted for this assessment, which were inundation, structure damage, wind damage, and structure type. After putting in the domain you want to add codes/descriptions that are going to be used when trying to interpret the data. The image below is a look to the different domains with the view of the code/descriptions of the structure damage.

After creating the domains and the codes/descriptions we created a new feature class that has the different fields with the domains. Even though the directions say "No" on the Allow Null portion you do need to say yes in order to actually create the features. In this portion we needed to classify the structure damage. When trying to identify the properties I was looking at the pre-storm image to see if the structure looked like people would be vacationing or living there versus a commercial place. The scale that worked the best for me was between 1:500 and 1:250. I was trying to see the surrounding area to see if the structure was affected or there was no damage. The decisions that were the most difficult were trying to decide the line of when the structure is inundated or not. There is a lot of sand around but in these areas many of the structures are higher from the ground so they could be perfectly fine. Another difficult decision was trying to decide wind damage because this is an image it makes it hard to know what was wind and what was water. I would say I would like another image that was at the same time as the previous image because it made it hard to know what was wrong with the structure and what was a shadow. Also, I think we should add another structure type of commercial because I was having a hard problem with wanting to put unknown because I knew it was commercial and not industrial. A last piece of information would be the structure height to know if the structure was inundated or not from the water and sand. The image below is a view of the different points I put on each structure.

Lastly, we needed to take the data we created an analysis the data to understand what it happening post-hurricane sandy. To get the information I needed to know the distance was by using the Near geoprocessing tool where I could get the distance of the structures from the coastline. It did show that there were four structures that were past the 300-meter radius. Also, to get more structures I did have to change my coastline a little because it was not showing the structures. Lastly, I looked at the near distance portion of the attribute table and saw that most of the structures were 92-meters and above. This is interesting because if you focus on just the distance you might not get the information for all the structures. It looks like the closer to the coastline the more likely the structure is either destroyed or has some major damage. At the same time, further away from the coastline it does look like the structures were more affected by the hurricane. I would say it is reliable because I kept the same thought process while I was analyzing the data. The only problem I had was only being able to see the top of structure I was having hard time telling how much was damaged. I based the decision on the sand a debris surrounding the structure.