GIS Reacts to Major Flood: Story of Dubuque, Iowa’s Record Rain Event

GIS Reacts to Major Flood: Story of Dubuque, Iowa’s Record Rain Event
September 8, 2011 Mike Tully

Interview by Joshua McNary with Nikki Breitsprecker

Back in July 2011, people in the City of Dubuque, Iowa went to bed amongst some thunderstorms, not unlike many Summer evenings in Iowa. When they awoke the next morning, they realized something was not right. The heavy rain storms had continued the entire night. Within twelve hours the area was deluged by 10-15″ of rain. At the same time, Nikki Breitsprecker (GIS Coordinator/Analyst) was contemplating her departments role in reacting to an unprecedented weather event that had hit her beloved hometown.

Aerial Services, Inc. (ASI) asked Nikki about the event, aftermath, and recovery efforts. She provides context and suggestions as to how other geospatial professionals can be prepared for spontaneous events like this one and allow remote-sensing and GIS to shine in an hour of need.


[h3]What happened in Dubuque during the overnight hours of July 27-28, 2011?[/h3]
The City of Dubuque received record-breaking rainfall, over 14 inches in about twelve hours, on July 27-28. It started with what appeared to be a small group of thunderstorms around 6 PM on the 27th, and it didn’t let up until the following morning. Dubuque has never experienced a rain event like this in recorded history!

All images: Copyright 2011 – Aerial Services, Inc. (ASI). All Right Reserved.

[h3]How widespread was the damage? What were the worst effects experienced? Were you affected directly?[/h3]
The damage from the storm was widespread throughout the City and surrounding area. The storm runoff quickly incapacitated the storm water system in some parts of town and also inundated sanitary sewer because of inflow & infiltration. This caused a significant amount of street flooding, sewer backups, and flooded basements. People in low-lying areas had to be evacuated because the waters rose so quickly. Emergency responders worked all night to block impassable roads and rescue individuals from their cars and homes. There were thousands of reports across the City of flooded basements, downed trees, and property that had been literally washed away. A residential area in downtown Dubuque was particularly inundated with floodwaters. Of the 260 property owners who requested basement pumping after the storm, the majority were in an area north of E 20th and east of the bluffs. Of those basements that flooded, most reported a water level between 8-12″, but some people had as much as 7′ of water in their basements. Others had the foundations of their homes cave in. The storm water runoff also caused a significant amount of damage at our under-construction water pollution control plant, washed out several hundred yards of train tracks, and destroyed low-lying recreational areas.

I woke up that morning to a dry basement and no property damage. Others were not so lucky.

[h3]What was your reaction as a GIS professional to the event? How quickly did your GIS department react to supply maps, analysis, etc.?[/h3]
When I woke up on the morning of July 28, I really had no idea what the extent of the storm was. I noticed the rain gauge in my yard was completely full, but it wasn’t until I turned on the news that I knew how big of a deal this storm really was. Immediately I started thinking about possible damage and the data I’d need to get ready that morning in preparation of map and data requests from various agencies. I expected to be inundated with map and data requests immediately that morning, but City leaders were shoulder-deep in disaster response. The requests didn’t come until later that afternoon, and when they needed data, I worked as hard and fast as I could to produce useful maps for City staff to respond to the disaster.

[h3]What mapping tasks were you called to achieve in support of the recovery effort?
[/h3]
City leaders wanted to know where damage had occurred – we had several different departments responding to various calls for service. The first data set mapped was requests for basement pumping. Other data sets that were mapped included damage reports (provided by a partnering agency), sewer maintenance requests, street cleaning requests, sanitary sewer overflows, and tree removal requests. These maps were updated one to two times a day for the following week depending on the data provided from various departments and to GIS.

[h3]In aftermath of this unplanned event, what existing geospatial infrastructure were you most happy you had in place?[/h3]
I don’t know how we would have responded to this without GIS. I was very thankful we had recent aerial imagery, topography, and up to date and accurate infrastructure and base map information. Because our road information was accurate and up to date, I was able to easily geocode the addresses of citizen requests. I used our neighborhood boundaries to quickly delineate areas of town where assistance requests were higher. In those neighborhoods, I was able to use our geocoded utility account and parcel information to identify property owners, addresses and household counts so interns and volunteers could deliver information to those citizens. We also used our watershed feature class with the calls for service to identify which watersheds were most impacted. We can use this information in future storm water management applications.

[h3]Aerial Services provided you with ‘quick ortho’ imagery, how was it useful to have aerial imagery from right after the event occurred? What was accomplished with the imagery?[/h3]
Having imagery from the day after the storm was a huge benefit in realizing the full extent of the damage that occurred in the City. While the floodwaters had largely receded from the streets, it was very obvious from the aerial photography where storm damage occurred. We were able to see residential neighborhoods that still had standing water, where creeks had risen based on the vegetation around them being flattened, damage to our water pollution control plant, part of a bridge that had washed away, and bluffs and hillsides that had given way. One thing I didn’t see was debris and downed trees blocking streets. That spoke to the amazing efforts our City crews made the night of and the morning following the storm.

If this imagery wouldn’t have been available, we would have had to rely solely on pictures from cameras (if people had taken them with and thought to take pictures) and verbal reports of damage, and we never would have been able to have a quick assessment of the aftermath of the storm.

 

[h3]Do you have suggestions for other cities or organizations to prepare for unplanned emergencies like this one? What procedures or changes would you put in place?[/h3]
Be prepared. Know who your partners are. Help your City leaders know and appreciate the need of geographic data for situations like these.

The City of Dubuque was well-equipped to handle disaster response in this situation – City leaders quickly identified the severity of this situation and activated the City’s Emergency Operation Center (EOC) in the early hours of July 28. They knew which other organizations to contact in order to provide assistance to the residents. The City’s Engineering Department has been working for years to restructure storm water runoff in the community, especially those areas prone to flooding, and the work that had been completed to that point paid dividends in this storm. Things were still bad, but they could have been a LOT worse. Finally, the City’s support and use of GIS in this event was crucial – managers knew they could use tools in GIS to effectively map out data related to the storm. I was able to provide many different departments a wide range of data from a variety of different sources – all using GIS. When FEMA came to town 36 hours after the storm, we had maps of the damage ready to show them. We turned out a lot of information in a short amount of time because of our proactive data management.

[h3]What was the number one thing you will take way from this event as a citizen of your City and as a GIS professional?[/h3]
It’s hard to pinpoint one thing to take away from this event, because we all learned so much. As a citizen, I was proud to see how quickly and well the City responded to the situation. They kept the community well-informed of storm-related and clean-up efforts, and they didn’t wait around to clear streets and begin the clean-up and repair process. As a GIS professional, I appreciated how proactive we’ve been in data development and maintenance. Our incident management database and our GIS were crucial tools in recovery efforts.


In response to an rain event, Aerial Services, Inc. (ASI), acquired, processed, and distributed disaster response imagery of Dubuque, Iowa and the surrounding area. The data was offered to City and County officials and members of the media as a courtesy in a time of need. To learn more about this effort and learn how you can get disaster response imagery for your community, visit Aerial Services webpage.

To reach Ms. Breitsprecker, ask questions, or make comments please contact Aerial Services’ Marketing Manager, Joshua McNary, at jmcnary@AerialServicesInc.com or 319-277-0436.