Del Mar College

Challenge: Mapping Hurricane Flood Damage Potential
Solution: ArcMap 9.3 Maps of Coastal Area

Academic Challenge

Del Mar College is located in the low lying coastal area of the central Texas coast, known as the “Coastal Bend”. It has a long history of hurricane damage since its founding in 1846 by Col. Henry McKinney. The city of Corpus Christi is the largest municipal area along the coast, with a population of some 300,000 residents (2009 Census). It lacks transportation routes out of the low-lying coastal zone to higher ground inland, like San Antonio and Austin. The single Interstate route, I37, requires lane-reversals for 150 miles to accommodate the flood of passenger autos during a 24 hour storm evacuation order.

The GIS program at Del Mar College offers certificate and Associate degrees in GIS Technology. The program, which started in 2000, trains approximately 25 graduates annually, who are hired by the local workforce, including: city & county governments, private engineering & surveying firms, and environmental consulting companies. Students in the program are engaged in community-based project from their first GIS course right through to their capstone internship course the final semester. One such project was performed for the local City of Corpus Christi Municipal Emergency Planning & Response Council to map the extent of possible flood zones, based upon the storm level (Category 1-5) and the possible escape routes, based upon flood levels through time. Such an extensive project provides a tremendous amount of work opportunity for students across several semesters, as they gather data from online sources or generates the data through GPS field trips. It requires advanced geo-processing logic and workflow, as they utilize Network Analyst extensions attempting to process all the possible routes with several variables, such as rainfall total, terrain topology, and real-time road closure reports.

Geospatial Solution

Under the skilled instruction of Barbara DuFrain and John Nelson, GIS students at Del Mar College built a series of maps depicting the areas of the county and city that would flood, based upon the level of sea level rise and inundation from approaching storm surge from the hurricane. Knowing that the sea rises X number of feet for every Y increase in wind strength, and using digital elevation model (DEM) data from reputable data sources, students are able to build flood maps showing precisely which streets and blocks will be flooded and when. Students utilized data acquisition, quality control and assessment skills in obtaining the DEM data. The information was used to create a geo-database in ArcMap 9.3. Once the base map of the flood zones for a Category 1, 2, 3, 4, and 5 storm was developed, the next tasks was to map possible escape routes from approaching flood waters for City of Corpus Christi Emergency Planners. [It should be noted here the maps created by the Del Mar College students are obviously not the final product used by the City planners for issuing evacuation orders on. They are instead an academic exercise for students that are based upon a real-world need. This hybrid method of project-based learning engages our learners to a higher level of participation and enthusiasm, as they realize their work with have, at minimum, influence on the decision makers during a time of crisis.]. Next the students were required to identify those streets and highways that provide the best means of escape to the interior of Texas, such as Laredo or San Antonio. These routes are based upon several complex factors: road elevation, number of feeder road connections, population density along the route, travel time, distance, condition of the road, and traffic capacity of the route in terms of number of cars per hour it can safely handled. Such sophisticated geo-processing requires Network Analyst extensions to perform the complex analysis.

Benefits

Students learn the methods of encoding the information requirements and designing the work flow for the geo-processing. The end product is a series of maps depicting the flood zones and recommended escape routes to better serve the citizens of the Coastal Bend, while providing our learners with meaningful community service project experience.

For more resources, visit our Geospatial Resource Repository.