Lab 8 - Damage Assessment

For our final lab we completed a mini-damage assessment within an area affected by Hurricane Sandy. Our focus specifically was a small section of coastline along the New Jersey shore.

Aerial view of our storm damage assessment area (bounded by the pink box).
 

Damage Assessment

Aerial photos (taken before and just after the hurricane) were examined to determine the extent of the damage. As shown above, the study area was subdivided by ownership parcels; structures within each parcel were digitized and coded according to the visual extent of the damage shown in the aerial photographs. The digitized homes are represented with triangles in various colors, the coding of which is as follows:

• red = structure was destroyed
• orange = structure had sustained major damage
• yellow = minor damage
• light green = structure was affected by the storm in some way
• dark green = no visual structural damage

The above categories were a bit subjective - the damaged and obviously not damaged structures were easy to code, but those falling between the two extremes were a bit more difficult. In general the code for "affected" was reserved for parcels that had previously only contained a parking lot, minor damage was characterized by evidence of other buildings jammed up into an otherwise stable looking structure, and major damage was reserved for buildings with partially missing sections. Field verification would be absolutely necessary to validate the above codes - the aerial analysis really represents a quick estimate based on imperfect data (poor lighting, pixilation, the inability to see wall damage, etc.).

Summary of the Damage Assessment Results

In all a total of 127 separate structures were identified and coded based on viewing the pre-Sandy aerial photos. These structures were further sub-divided into groups based on their distance from the pre-Sandy coastline. A series of distances were created using the Multiple Ring Buffer tool in ArcGIS (distances ranged from 0 - 100 m, 100 - 200 m, and 200 - 300 m).

Once the distance extents were established the digitized structure points were selected based upon their location within each buffer zone. The results were tallied by the number of structures within each distance zone as well as a count of each structural damage type per buffer zone (using the Summary Statistics tool). The results for my analysis are shown below.

Structural Damage Category	Count of Structures within Distance Categories from the Coastline
	0 – 100 m	100 – 200 m	200 – 300 m
No Damage	0	32	44
Affected	5	11	6
Minor Damage	0	0	1
Major Damage	2	3	1
Destroyed	8	13	1
Total	15	59	53