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Elected Leaders, Representatives Of Protective Associations Hear Update On Iowa Great Lakes Flood Modeling Project

Wed 11-28-2018

(Okoboji)-- Local elected officials, representatives of lakes area protective associations and others today (Wed.) heard a presentation on some modeling being done in an effort to prevent future flooding on the Iowa Great Lakes.

The Iowa Great Lakes Association is footing the bill for the $125,000 study that's based on modeling put together by Dr. Larry Weber of the University of Iowa Hydroscience and Engineering Department and a couple of associates. He says the model was developed through a $96 million HUD Grant. Dr. Weber says the model has already been used on some other flood prevention efforts in other parts of the state. He says it's based on detailed ground and surface water data...Dr. Larry Webber01 

"Ground water is such an important driver in the lake level. Surface water of course coming from, rainfall that comes from the atmosphere, from the rain water side we use all of the rainfall products from the National Weather Service and their Nexrad rainfall radar network that overlooks Iowa. You know we get all of our land cover, soils information from the USDA and the NRCS, we get land use data, you know housing and different urban activities are going on, all that's incorporated into the model, so every sort of imaginable, physical thing that's out there is somehow represented in this mathematical model."

Dr. Weber says their preliminary goal is to have a report based on the modeling completed by early this coming spring...Dr. Larry Webber02 

"I can see from today's meeting the interest here and looking at some different elements that we might not have included, we really do think we'll have the model calibrated in early January. We'll go through the scenario development work, probably be back up here let's say by the first of February, present that, get feedback on it, use that feedback then, maybe do another simulation or two and then write that up in a draft report we think by the first of April or so."

Dr. Weber says the study will focus mainly on the Lower Gar Outlet...Dr. Larry Webber03 

"The real driver behind the start of the study was to think about what the structural changes could be at the Lower Gar Outlet, so changes or additions to the culverts that are there, would another culvert help, would it help to convert those culverts to a bridge, would it help to fully remove that structure, then that sort of immediately would let us to look at the DNR fish barrier and weir that's downstream, that clearly has an impact, we have to look at that. And then any time we do these studies it's important for us to put an eye to the future. We want to make sure that whatever we do today is done with a thought towards climate and increasing rainfall intensity because we don't want our design to all of a sudden be outdated in a few years. So we're going to look at some increased rainfall intensity and some other things as well."

Dr. Weber says that report will likely contain several recommendations...Dr. Larry Webber04 

"So what we'll do is we'll evaluate scenarios and then we'll kind of rank them in terms of lake level factor impact. So it would be I'd say recommendations is a good word. The term endorsement was used today and I would say we wouldn't endorse anything. That's really left for the folks here to decide what they want to endorse, but we will make an engineering recommendation."

Dr. Weber added it likely would be atleast a couple of years before construction would get underway on any projects. In addition to getting approval from local and state officials and financing, permits would also be required from the U.S. Army Corps of Engineers.