Archive for the ‘Red River Flooding’ Category

Fargo diversion and downstream river levels

Friday, August 20th, 2010

A controversy has developed over whether the proposed Red river diversion at Fargo Moorhead will increase red river levels downstream in flood.  The corps state it could add 16 inches to the river level at the Thompson Bridge.

If the diversion is properly designed my view is that this is highly unlikely.

A letter from myself to the editor of the Grand Forks Herald was published  08/19/2010: –

LAPORTE, Minn. ? I served on the mayor?s task force for flood protection for Grand Forks/East Grand Forks after the Flood of 1997. As part of our research, we studied the Winnipeg flood diversion project extensively. We also were advised by the engineers for the original Winnipeg diversion channel, Acres International. And, we had advice and counsel from the developer of the project, Ed Kuiper of Winnipeg.

Kuiper explained to me at length that a properly designed diversion channel does not raise river levels downstream. What it should do is channel the water that is out of the riverbank doing damage, to a safe channel where it does not do damage. The flow through the city in flood or the contained water in the channel should be the same.

The only river levels that change and are elevated are the levels upstream as the diversion channel is brought into operation. This is because as the gate is raised in the riverbed, the river level will rise to force the river over the lip of the diversion channel.

Richard Nelson, the late mayor of Warren, Minn., had a diversion for the Snake River designed not by the Corps of Engineers but by Acres International of Winnipeg. I discussed this project often with Nelson before his untimely death.

Warren had multiple floods every year. It has not flooded since completion of the diversion channel on the Snake River. I cannot find any data that suggests river levels increased on the Snake River downstream.

Having seen the workings of the Corps up close, I?m highly suspicious that they are touting these absurd rises in river levels to kill the Fargo-Moorhead diversion project. They killed the excellent Grand Forks diversion project by grossly inflating its cost.

Kuiper and others have pointed out that flood protection needs to protect against a 500-year event. Building to a 210-year event is totally inadequate. Remember, if you build for a 210-year event, you have a 1-in-210 chance of a flood each and every year. The figure does not mean you will get a flood every 210 years.

So, if you build to a 500-year event you have a 1-in-500 chance of a flood every year, which is much better odds.

It is no secret that I was opposed to the Grand Forks flood-protection project and regarded it as inadequate. Today, I?m of the view that because of the topography and hydrology in the Fargo-Moorhead area, a diversion project is the only way of providing flood protection to those cities.

If the Corps really believes its project will raise river levels 16 inches at the Thompson Bridge, then it also should build the diversion project to the west of Grand Forks ? which it should have done and still needs to do anyway.

Mark Carter

Red River of the North: – A history of flooding and possible mitigation.

Saturday, April 4th, 2009

The Red River of the North arises from the the two stem rivers, the Bois de Sioux staring at Lake Traverse and the Ottertail River arising near Alexandria Minnesota.  It forms the boundary between Minnesota and North Dakota.  It crosses the US/Canadian border, entering Manitoba at Pembina/Emerson.

The Red River of the North runs its way North to Lake Winnipeg.  It follows the lake bed of Lake Agassiz.  The only remnants of this lake, the largest of the North American Pleistocene lakes, are Lakes, Winnipeg, Manitoba and Winnipegoshi.

The Red River has a wide flat valley, which has  outer, middle and inner thirds, with progressively decreasing slopes.  So the water falls faster in the outer reaches of the valley, getting funneled into the inner third were the slope is only one foot per mile.  Added to this the River flows North into colder regions.

It is therefore not surprising that the Red River is prone to severe spring floods.

The following factors in addition to the above contribute to this problem.

The Autumn is often wet, and the winter freeze can come quickly, and freeze a lot of water in place.

It stays cold until early Spring and warm up can be rapid, and a lot of water can flow into the inner valley quickly.

Springs are often wet adding more water to a critical situation at the wrong time.

Ice jams are prone to form, especially as flows start in the south flowing into a frozen river down stream.

The fall is only 1 ft per mile so flows are slow.  The flat terrain enables the river to spread out across the valley, 60 miles being recorded south of Winnipeg in years past.  This results in severe flood potential, with damage to structures and agriculture, many miles from the river.

Geologically the Red river is a young river, shallow and without steep banks, and lots of oxbows.  The banks have a lot of unstable over banking.   It also has a huge watershed, in which the Minnesota watershed is significantly dominant over the North Dakota watershed.

The issue of agricultural drainage is often cited as a cause.  However a review of a history of Red River flooding shows that flooding was even more severe prior to cultivating the Red River Valley for agriculture.

Here is a history of main flood events in the Valley, not including this years severe flooding which is not over yet.

{Floods1700s Large flood in 1776 according to anecdotal accounts; floods in Canada, especially in 1747 and 1762, substantiated by tree-ring evidence.1826 Flood of record in Canada that destroyed settlements.1882 Large flood at Fargo, N. Dak./ Moorhead, Minn., and Grand Forks, N. Dak./East Grand Forks, Minn.1897 Largest flood on record at Fargo. 1916 Large flood in Fargo and on upstream reaches; sizeable flood in Canada.1943 Large flood in Fargo/Moorhead; in an 11-day period, the Red River rose about 23 feet; St. John’s hospital was engulfed and 270 families were forced from their homes.1950 Flood that caused most severe damage ever sustained up to this point–extended time for flooding; major disaster in Winnipeg with one-third of city evacuated.1965 Widespread flooding caused by heavy rain on frozen ground.1966 Severe flooding from United States/Canada border to Winnipeg.1969 Maximum discharge recorded on the Red River at Fargo/Moorhead and Wahpeton, N. Dak./Breckenridge, Minn., and in some areas on the Sheyenne River to this date; first flood to be diverted around Winnipeg by Red River floodway. 1975 Flood that included two peaks, in spring and summer.1979 Second largest flood after 1897 (to this date) at Grand Forks and in Canada.1989 Flood that severely damaged the cities of Wahpeton and Breckenridge.1993 Summer flood caused by a series of intense thunderstorms at various locations throughout the basin. 1997 Major flooding in United States and Canada; largest recorded flood in Grand Forks/East Grand Forks; second largest in Fargo/Moorhead and Wahpeton/Breckenridge.2001 Significant flooding caused by heavy rains on frozen ground in addition to above-average snowfall. 2002 June flooding in northwestern Minnesota, especially in Roseau, Minn., and northeastern North Dakota caused by intense rainfall.2006 Spring flooding throughout basin; most cities well prepared because of improvements made since 1997.}

But not so well prepared in 2009 it seems.

If anything agriculture has most likely slightly mitigated flooding, because of the section roads, and their culverts.  These culverts often remain frozen and hold back water on the fields.  The author believes this factor likely saved Fargo form devastation in this year’s first crest.

These devastating floods occur with a frequency that makes a mockery of current incidence ratings, with 100 or even 500 year events occurring every decade or so.

These floods occur when the temperatures in the region can be harsh, below freezing and deliver punishing snow and ice storms.  These spring flooding events inflict untold misery on the inhabitants of the Red River Valley.  It is long passed the time were this recurring disaster should be a national, and now international media spectacle, to see how much misery the population can stoically endure.

After the devastating Red River flood of 1950, in which the inhabitants of Winnipeg had to be evacuated under very difficult circumstances, the Manitoba premier Duff Roblin, was instrumental in the building of the Winnipeg Flood way.  (Duffs Ditch).  This is one of the most remarkable civil engineering projects in the history of man. (To watch an interview with Duff Roblin and Ed Kuiper, click on video 3 on the above link.)

This is the story behind Duff’s Ditch and flood mitigation projects in Manitoba.

As a result of the the devastating flood of 1997, which devastated Grand Forks and East Grand Forks,  the architect of Manitoba flood mitigation, the dutch hydrological engineer, Ed Kuiper determined that the Winnipeg flood way needed an increase in capacity of at least a third.  Manitoba embarked on the Winnpeg floodway expansion project.

This project is coming to fruition.  Its progress can be followed here.

After the flood of 1997 the author was a member of the Grand Forks mayor’s flood committee to consider mitigation.  I think it is fair to say the committee favored a Grand Forks flood way to the west.  Ed Kuiper, whose engineering has been so successful and the original civil engineers of the Winnipeg flood way, Acres International, drew up a well fleshed out, and cost estimated, a diversion channel to the west of Forks on the ND side.

However the American Army corps of engineers would not sensibly consider the plan, and pressed a rush to dikes.

This is their completed plan.

It involves two problematic ring dikes to protect East Grand Forks.  There is a combination of compacted clay dikes, flood walls, removable flood walls and diversions.

Fargo has had no significant flood mitigation projects since the 1997 flood.

In conversations the author had with Ed Kuiper after the 1997 flood he was of the opinion that if a significant fraction of the added capacity of the Winnipeg flood way was ever used protecting Winnipeg, then no diking scheme would protect the large population centers of the Red River Valley in the US, and that included, the then proposed and now completed project at Grand Forks/East Grand Forks.

He is opposed to ring dikes because, unless a population is evacuated in times of flood, people become trapped in the event of a levee failure.  He also is not in favor of high diking, on the unstable soils of the Red River Valley, only low to medium diking.

So what options are there for mitigation?

Holding back water in the outer tributaries would provide some mitigation.  The Red River Watershed Management Group have some proposed projects in this regard.

The ERC at UND through the Red River Water Management Consortium have been proposing the waffle plan.   This invoves holding back the water on fields, and releasing the water in a controlled manner with the use of sluice gates.  This plan  can be shown to take 2ft of just about any flood event, and may be under some circumstances 3.5 ft.  Whether there is enough benefit to the cost of placing, managing and controlling those sluice gates is questionable.  How to make the system relibale, in the freeze thaw cycles of the Red River Valley region would take research.

However none of the above measures, even in combination would prevent devastation in severe flooding.

That leaves the option, of levees, flood walls and diversions.

The geology of the Red River Valley makes high diking a poor option.  The experience in Winnipeg has shown that a combination of low to medium diking in combination with a flood way  provides reliable protection, with minimal stress on the communities in times of flood.  This is the split flow solution, and the author’s opinion the optimal solution for mitigating flood devastation in the Red River Valley.

Even for small communities this can be a good cost effective option.  The town of Warren Minnesota suffered frequent floods form the Snake River.  They even achieved the distinction of having three devastating floods in one year.  The late Richard P. Nelson, who was mayor of Warren, brought to fruition  a Snake River diversion at Warren.  In the floods this year, the Snake River at Warren stayed below flood stage!

The brilliant Dutch hydrological engineer, Ed Kuiper has a proven track record of succesful flood mitigation in Manitoba curbing the devastating floods on the Red and Assinboine Rivers.  He has used a combination of holding dams, diking and diversions.  He is now 87.  However time has fortunately not dulled his mind.  He is the greatest expert alive on flooding in the Red River Valley.  I know he has well founded opinions about correct mitigation of flooding in the US portion of the Red River Valley.  After this years experience in Fargo/Moorhead, a high level political delagation from North Dakaota and Minnesota should consult him without delay.  Soon it will be too late!

Fargo should move to build a split flow diversion rated to a 700 year event without delay.  Grand Forks should have a diversion channel added to the West to keep water below the Sorlie bridge in a 700 year event.