by Shianne Gruss
For Iowa City residents and University of Iowa students, it’s impossible to forget the floods of 2008 – not with more than a dozen different flood mitigation and recovery projects underway across campus.
Luckily, the Iowa Flood Center (IFC) continues to work hand in hand with the Iowa Department of Natural Resources to better inform citizens of Iowa City, and countless other communities across the state, of potential flooding.
The IFC stream-stage sensors, an idea pioneered by both UI engineering students and faculty back in 2010, have been an “overwhelming success,” says Dan Ceynar, an IFC engineer.
Of the 100 sensors funded by the DNR, the first 50 sensors installed have been revisited just once or twice for minor updates. The majority of the more recent sites, however, have never required a follow-up visit.
“When the IIHR approached the DNR about the stream-stage sensors that they developed, we felt it would be a great way to see if the information provided by the stage-sensors would fill in some of the information gaps, especially for local emergency managers and having time to respond to a potential flood event,” says Lori McDaniel, supervisor of the DNR’s Division of Flood Plain Management, Dam Safety, & Water Quality Standards.
The sensors, priced at $3,500 apiece, are a system of electronics, modems, and antennas encased by weather-resistant aluminum and installed on the downstream side of bridges. Each sensor emits an electronic pulse to measure the distance to the water below and sends that data via cell modem to a central database every 15 minutes.
Earlier this spring, about 15 sensors sat submerged in a wet tank, being tested for leaks, in the IIHR Hydraulics Wind Tunnel Annex. With more than 50 more in progress, Ceynar estimates the IFC has built a total of 250 sensors, most of which are the new and improved models.
These second-generation sensors measure distances of roughly 44 feet, 10 feet more than the first batch. The improvement was necessary for bridges more than 20 feet in height. The newer sensors have also shed their radio-like communication capability — a feature Ceynar says went virtually unused.
While the majority of the sensors were installed at request of the DNR, many Iowa municipalities, counties, colleges, and universities have asked the IFC to install sensors of their own — and the list keeps growing. Even state and federal agencies, such as the Iowa Department of Transportation and the National Weather Service, have had sensors installed at various locations.
“I use gauges as one of my agency’s tools to prepare for and predict rising water levels, which in turn causes a list of various actions to take place,” says Larry Hurst, director of Mills County Homeland Security & Emergency Management Agency. “[I] would actually like several more units installed in my county.”
Although the IFC is the only academic flood center in the nation, it functions as a non-profit and must approach partnerships with caution, says Ceynar.
“The IFC bridge sensors receive quite a bit of interest from other states, as well as from other agencies and engineering companies as far away as Australia,” says IFC Director Witold Krajewski. “While currently we have no plans to create a for-profit company that would market the sensors, we feel that our impact would be greatest through some kind of a national or regional flood research center. We are exploring different avenues toward this.”
Citizens are encouraged to use the Iowa Flood Information System (IFIS), an online maps-based application, to view the stream-stage information for their area.
Easy-to-access, science-based information is one of the best tools we have to defend against flooding, says Iowa Flood Center (IFC) Associate Director Nate Young.
Working with the Iowa Department of Natural Resources, Young’s team of 16 IFC engineers, GIS analysts, and students is about halfway through a six-year project to develop upda
ted floodplain maps for the 85 Iowa counties that were declared Presidential Disaster Areas after the 2008 Iowa floods. The remaining 14 Iowa counties will be mapped by the U.S. Corps of Engineers.
“The maps will provide Iowans with good information concerning flood risk in their own communities, so they can make informed land-use and land management decisions,” Young says. The maps will define the boundaries of flooded areas for 100-year (1 percent annual chance of flood) and 500-year (0.2 percent chance) floods.
Iowa Flood Maps Online
The new draft flood maps are being posted online at http://www.iowafloodmaps.org as they become available. The flood mapping team began its work in southwest Iowa and is working its way northeasterly across the state (Iowa Floodplain Mapping progress map).
The easy-to-use Google-maps based interface allows Iowans to directly access information about their flood risks. While the entire library of IFC flood maps is being developed to the standards of the Federal Emergency Management Agency (FEMA), not all of the maps will be adopted by FEMA as regulatory documents. The remaining, non-regulatory maps will be available on the website to provide accurate information to Iowans, but will not be considered FEMA regulatory maps.
Partnering with the DNR
The IFC researchers are using laser radar (LiDAR) data made available by the Iowa DNR to map all streams draining one square mile or more. LiDAR is a remote-sensing technology that allows researchers to develop precise digital elevation models of the land surface. LiDAR data allow the team to describe Iowa’s river and stream networks, develop computer-based flood simulations, and delineate floodplains with reasonable accuracy.
Young, who is also an associate research engineer at IIHR—Hydroscience & Engineering, says the scope of the project is enormous. “Scaling the project up to the entire state and developing and managing such a large volume of data is daunting,” Young says. “We have hired a large number of engineers, GIS staff, and students dedicated specifically to the project. Our partnership with DNR has also been a great help in that regard.”
According to IDNR Floodplain Mapping Coordinator Scott Ralston, public meetings in each county after the draft flood hazard maps are published will give Iowans a valuable opportunity to learn more and offer comments and feedback.
Plans are underway to expand the project to provide more mapping projects of particular interest to farmers. Duane Sand of the Iowa Natural Heritage Foundation hopes to raise $1.2 million for an additional two to five years of work to develop flood maps for the 2-, 5-, 10-, 25-, 50-, and 200-year floods.
With just under three years to go before the original mapping work is done, Young says he’s feeling confident that his team will succeed in completing the assignment on time. “We’re gaining momentum,” he says.
Iowa State University Extension, in collaboration with the Iowa Department of Natural Resources, has created a new series of educational web-based videos about all things flood-related: floodplains, flood risk, and basic floodplain management principles. The Flooding in Iowa Project divides the subject of flooding into five categories:
- Introduction to the National Flood Insurance Program
- Understanding Flooding
- Floodplain Mapping
- Floodplain Regulation
- Flood Insurance
The videos are available online at the ISU Extension website:
The website also includes a Frequently Asked Questions section, and links to other flood-related resources.
Iowa Flood Center
The University of Iowa
100 Stanley Hydraulics Laboratory
Iowa City, IA 52242
Contact: Breanna Shea