Flood walls look nicer all the time
May 21—No one wants to see the damage and inconvenience caused by a big flood.
But that doesn't make them any less fascinating.
As the Minnesota and other rivers rose to new crests last week, some of them in the record range, people came from near and far to take a look.
Whether it was the raging flow of Minneopa State Park waterfalls or the Rapidan Dam, the high and wide Minnesota River or the lowland flooding that covers land along any of the rivers, watching the power of the water is irresistible.
Of course, watching the water roar is one thing. Knowing the heartache people deal with when their homes are flooded is another thing.
This area has gone through plenty of massive floods that caused widespread damage. The floods of 1951, 1965 and 1969 are still remembered by anyone old enough to have witnessed them. All three rank in the Top 10 highest river levels in Mankato.
But as climate change fuels heavier rains and more efficient farm drainage has brought more water to the rivers more quickly, the number of record floods has grown more frequent in recent times.
Six of the top 10 highest river crests in Mankato have happened in the past three decades, including the highest level ever measured, at 30.1 feet in 1993.
And it's likely more record crests will come more often in the years ahead.
Which makes the big, ugly, gray flood walls that run through Mankato and North Mankato more attractive all the time.
Living in a house in lower North Mankato, not far from the river, I find the security of the flood wall is a comfort. The area where we live was long ago a river floodplain that was routinely under water. There's still a 3-foot dirt and sod berm running along our side yard that is the remnant of the earthen dike that was built to protect lower North Mankato from the 1965 flood.
Local officials had lobbied for the flood wall to be built and Congress authorized the project in 1958. But funding wasn't attached and there was no wall when the record-breaking flood arrived in April 1965.
It wasn't until the late 1960s that the Army Corps of Engineers began designing a flood-protection system that was much larger than earlier considered.
Work began in phases in 1971 with much of the main flood walls built from 1978 to 1980. By 1985 the flood system was mostly done with the last piece being removal of the old Main Street Bridge, replaced by the higher Veterans Memorial Bridge. The cost of the flood-protection system was more than $97 million.
When the Army Corps of Engineers decides to build something, they build it to last.
It ain't pretty, but the old gray walls have kept the cities dry for more than 40 years. Whether they are high enough or the overall flood drainage system is big enough to handle floods to come is another question.
Around the world cities and countries have built amazing flood-control systems. The world's biggest storm surge barrier, in the Netherlands, is called Delta Works. They began designing and building the system after a devastating flood in 1953. The project was finally completed in 1997 at a cost of $5 billion ($18 billion in today's dollars).
If you grew up on a farm, or in any home that had a well, you may have experience with a cistern, basically a big room in the basement that held water from the well that was then used in the home. So you might appreciate a flood-control project built in Tokyo.
They built tunnels and five giant cisterns under the city, held up with a series of 500-ton columns. The engineering marvel, finished in 2009, is unseen by anyone in one of the world's most populous cities.
New Orleans and other U.S. coastal cities have had their own massive flood-protection projects. More will be coming.
Let's hope our old flood walls will continue to be enough to handle the job. If not, the Army Corps will know how to reinforce it.
Tim Krohn can be contacted at tkrohn@mankatofreepress.com or 507-720-1300.
