GIS4930 - Module 1: Tampa Bay Hurricane Preparedness

Special Topics in GIS
Module 1 Tampa Bay Hurricane Preparedness - Week: Prepare/Analysis

Hurricane preparedness was the theme for the first week in Special Topics.  The setting is the peak of hurricane season.  The Gulf temperature is very warm, and the month of September is very hot and steamy; several unnamed tropical depressions, rainstorms hovering in the Caribbean and two Gulf of Mexico hurricanes (Jaws and Deliverance) set the stage.  Jaws is a Category 1 storm and Deliverance is a strengthening Category 3 storm; and Downtown Tampa Bay, FL is hoping for some dry Sahara dust to weaken the present threats.  The general scenario for this lab is hurricane evacuation using ESRI’s ArcGIS Network Analyst extension.  Project goals are routes, driving instructions, and evacuation maps.  A mind-map of this project looks like the following:

The first step was to gather and prepare various feature classes and transform them into a network dataset, which with the help of the Network Analysis extension (NAE) could generate a transportation network that could model evacuation routes.  The gathered points, lines, and polygons included: shelters, hospitals, fire stations, police stations, armory, roads, flood zones, study area boundary.   This collection of features comprised the network dataset.  The NAE would provide the logic of applying the appropriate routing methods, which would ultimately generate the final routes to be presented on public evacuation maps.  The end goal is polished evacuation maps to be televised to the public in preparation for a planned evacuation out of harm's way.

Data preparation consisted of organizing and preparing project data in a file Geo-Database (FGDB) and feature dataset.  Custom tools were used to clip all the project data to a region of downtown Tampa Bay and projection existing spatial data to a State Plane Coordinate System, NAD_1983_HARN_StatePlane_Florida_West_FIPS_0902.  A Digital Elevation Model (DEM) of the study area was reclassified by a Reclassify tool found in the Spatial Analyst extension.  The reclassified raster was then converted to a polygon using the Raster to Polygon Conversion tool.  A selection (grid_code < 6) of this polygon layer was saved and exported as the flood zone layer.  The road layer also needed some additional fields (Miles, Seconds, and Flooded) and values populated via the help of the Field Calculator. Finally, the metadata for these features was updated and exported using the Export Metadata Multiple tool.

The base map to the right displays the points, lines, and polygons feature classes that were gathered and prepared for setup in a Network Dataset, which will be available as input requirements for the NAE to perform various routing methods and generate line routes.  The Road feature (line) serves as the edge.  The Tampa point features serve as the junction network elements.  Various types of Network Analysis Classes (containers) exist for each type layer analysis that the extension can perform.  These classes are containers for network analysis objects, which work behind the scene at generating the routes we are hoping to discover.

Having the experienced the wrath of IRMA in 2017, the Analysis part of the lab was very informative.  I don't remember ever using the Network Analysis extension (NAE) in prior courses, but I'm glad to be reintroduced to it.  Below is an example of a map I made using the routes generated by NAE.  I used several legend inserts for the various scenarios of the project to help organize map content.  Balancing map elments and white space was fun to work out.

In summary, planning an evacuation route consists of three steps: gather inputs, select routing methods, and mapping the final routes.  Up to this point, the data has been gathered, massaged and ready for the NAE to act on to generate routes.  Well, I actually solved the routes this week.  After the data was prepared and a network dataset setup, several scenarios were analyzed: Tampa General Patient evacuation, emergency supply distribution, routes for distributing supplies, multiple evacuation routes for low-lying populated locations, and shelter map.  The final step is planning, creating, delivering a public evacuation story, and revisiting Corel Draw.

This week was a good practical experience of putting GIS tools into action and building a valuable skill (Network Analyst Extension) for the workplace.  The Lab instructions were pretty good.