The City of Mobile’s GIS system has a robust mapping system with multiple layers for stormwater features, including the city’s 34,000 catch basins. The city started its journey toward mapping stormwater features in 2006 using 1950s-era linen maps and, by 2018, had developed its GIS stormwater features layers using thousands of field and office man-hours by GIS analysts and interns. The city received a RESTORE grant in 2019 to obtain survey-grade information for all stormwater elements. A standard for field data collection was established for survey crews and work began. By 2022, the city had data collection substantially complete, and the survey consultant began actively doing QA/QC. With this newly acquired survey data, the city launched a nine-block pilot drainage project to analyze drainage system deficiencies. The pilot drainage project identified survey gaps, when the data was used to develop a stormwater model. The difficulty in the pilot project brought value to the city’s overall GIS mapping efforts. The city evaluated where the gaps were and localized trends were identified. Construction methods in the oldest areas of the city, combined with a number of drainage features being in backyards or “blind” manholes, have led the city to consider alternative techlogies for filling in data gaps that were encountered. Lessons learned and the next steps will be discussed.
At the conclusion of this session participants will be better able to:
• Apply Mobile’s techniques on taking available data such as lidar, aerial imagery, and engineer’s as-builts/plans and have a GIS analyst input the data from these existing sources. Take the base map that is created from available data and confirm it in the field.
• Acquire techniques to standardize data collection by GIS internal staff/interns, as well as survey field crews.
• Identify challenges to data collection and apply lessons learned in Mobile for better project data collection planning.

Contributor/Source

Martha Byrnes Jackson

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