Levees: Critical data for multiple uses

March 2013 » Columns » CE + GIS INTERSECT
Janet Jackson, GISP

Emergency response
I can't say the word levee without hearing the familiar lyrics, "Bye-bye, Miss American Pie, drove my Chevy to the levee but the levee was dry." It's common to associate a word or idea to a song as an easy way to remember lasting details. However, this song only helps you remember that the levee was dry, a rare case since a levee's main purpose is to regulate the water level and keep adjacent land dry.

The most recent and highly publicized levee breach was when the Mississippi levee system, one of the largest systems in the world (more than 3,500 miles), could not accommodate storm surge from Hurricane Katrina. Thousands of properties were destroyed as massive flooding changed the New Orleans city and surrounding areas forever. Could using GIS have altered these events? No. However, keeping all levee data organized, up-to-date, and reflecting current field conditions is a great first step in being prepared and proactive for the next storm event, no matter how big or small.

When a natural disaster strikes a large town, numerous agencies depend on critical and updated data to help them coordinate emergency activities. GIS data, along with mapping activities, is a huge boost to their planning, responding, and coordinating events.

When a natural disaster strikes a large town, numerous agencies depend on critical and updated data to help them coordinate emergency activities.

So, the next time you hear the song "American Pie," know that in today's high-tech world, you could save the drive by checking your GIS data files to find out the levee's condition – dry or wet!

Janet Jackson, GISP,is president of INTERSECT (www.intersectgis.com), a GIS consulting firm. She travels the country talking about the importance of intersecting GIS with other professions to create effective solutions for clients. She can be contacted at jjackson@intersectgis.com.

Levee certification
GIS technology can be applied to efficiently gather, analyze, and use data for levee certification. GIS is used to map and manage data for cataloging and retrieval from a variety of sources, such as plans, permits, inspection spreadsheets, photographs, and many others.

To unify the data, it is moved to a common GIS reference system. This automates translation between measurement systems, which saves time by eliminating river mile and levee mile calculation for things such as encroachments. GIS-mapped encroachment data is used to validate existing information in the field. Field crews identify, photograph, and document unknown encroachments or unauthorized improvements in the GIS using GPS-enabled tablets.

Encroachments have a relationship with both permits and parcels, which is classified as "many-to-many" since some encroachments can be contained in multiple permits and cover multiple parcels. This complex relationship leads to multiple filing and storage systems, all easily managed with the GIS. Creating and maintaining one repository for all the data allows it to be easily searched and viewed.

Building web reporting tools grants easier access to the desired data. Tools allow text searches by location, permit, parcel, and encroachment type. Links within the reports let the user view related data, such as all the encroachments associated with an individual permit and associated photos. Links to a web-mapping site allow point-and-click retrieval.

The convenience of GIS is found in its organization and comprehensive nature. Because the information is stored in a database, updates are orderly and efficient when it's time for the next round of levee certification. Mead & Hunt has successfully applied GIS technology for clients completing levee certification.

Ryan Meyer, GISP , is the GIS coordinator at Mead & Hunt, an engineering and architectural firm that provides consulting for water resources, aviation, transportation, municipal, and historic preservation projects. Meyer manages GIS and Technology Services projects, develops and coordinates GIS standards throughout the company, trains and mentors staff, and assists with quality control. He can be contacted at ryan.meyer@meadhunt.com.

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