Rivers run a costly race: Timing of crests key to unprecedented flood
FARGO - Micheal Kemp looks at the flooded rivers converging in northern Cass and Clay counties, creating islands out of farms and small towns, and sees the "mega-flood" that Fargo-Moorhead may someday suffer.
"We're experiencing kind of a mini-microcosm of what could be our future," said Kemp, an emergency management consultant who specializes in floods and lives in the flood-prone area between the Sheyenne River and Cass County 17 north of West Fargo.
It's a frightening prospect: What if the main rivers that affect metro-area flooding all converged at record levels at the same time?
River watchers say such unfortunate timing is the primary cause behind the vast pools of water north of the metro area, albeit on a smaller scale with different tributaries.
Consider this: In Fargo, the north-flowing Red River hit 38.75 feet on Saturday, the fourth-highest crest in history. A day later, the Maple River near Mapleton and the Sheyenne River at Harwood both reached heights two-tenths of a foot below their record marks.
"Usually you get some staggering of the tributaries, just based on timing," said Gregg Thielman, vice president and project manager for Houston Engineering of Fargo, which has studied water movement around the metro area.
"This year, it seems to have all come at once," Thielman said. "And you throw some rain on top of it and wind, that probably pushes more water through some of the breakouts than would have happened otherwise. It's kind of the perfect storm."
Road raise to blame?
Flooding across Interstate 29 will likely keep the highway closed from Fargo to Hillsboro for several days, "possibly a week," said Bruce Nord, maintenance supervisor for the state Department of Transportation.
Nord said Sunday he hadn't seen such severe flooding on the 12-mile stretch of I-29 near Argusville since the 1970s.
In April 1997, flooding forced the state to close I-29 between Harwood and Fargo for 11 days, said Bob Walton, DOT engineer for the Fargo district.
But that stretch remains dry now, thanks to a recent project to raise
I-29 bridges over the Sheyenne River. The project also included rebuilding and raising the northbound lanes of I-29 from County Road 20 to the Sheyenne River and the southbound lanes from County Road 20 to Argusville, which was completed last year.
Walton said officials don't believe the project is a factor in the unprecedented overland flooding affecting northern Cass County, as it was designed to have zero impact on flooding in other areas. Box culverts under I-29 that carried flows picked up by two legal drains were replaced with bridges for greater flow capacity, and a railroad bridge opening was widened for the same reason, he said.
Thielman, whose firm engineered the project, said the goal in sizing the bridges was to not affect the 100-year flood level on the west side of I-29.
"Because if we were to impact that, then it could potentially make things worse through Harwood," he said.
Backwater flooding occurs often in the Harwood and Georgetown, Minn., areas, where the Sheyenne and Buffalo rivers empty into the Red River, said Mike Lukes, National Weather Service hydrologist in Grand Forks.
"Basically, the degree of (flooding) can be affected by the convergence of crests," he said.
The National Weather Service tries to predict crests at river gauges on the Red River and its tributaries, but it isn't able to predict overland flooding - at least not yet, Lukes said. In time, LIDAR technology that provides high-resolution mapping of Earth's contours may change that, although the process is costly, he said.
"We're moving to this phase that we're talking about inundation mapping where we can take those river levels and kind of say, 'Well, if the river's this high at the gauge, we could extrapolate out on the topography and say what's going to be under water,' " Lukes said.
Kemp, who did his dissertation on Red River Valley flooding to earn his doctorate from North Dakota State University, said that during his tours of Reed Township north of West Fargo, "It does seem water is appearing in places that we've never seen it before, and it got on us much faster."
There could be a couple of reasons for that, in addition to converging river crests, said Kemp, a senior analyst for Chicago-based Integrated Solutions Consulting. One is that ongoing development of new roads and neighborhoods north of the metro is changing water flow patterns, he said. Another consideration, which he noted is "kind of controversial," is the draining of farm fields with drain tile.
"If you have those types of issues and that water is getting into our rivers a lot faster, it only makes logical sense that it's going to get down the river faster and get on people's property in this area faster," he said.
Readers can reach Forum reporter Mike Nowatzki at (701) 241-5528