|
southern MN | German Shepherd - 8/8/2026 08:59
OK, so why have the floods in the metro gotten so much worse than they were 50 years ago? We aren't getting more snow than we used except for '97 and yet the amount of water coming through Fargo is much higher now. I'm not convinced that tile isn't a factor and I've seen others cite tile for some or much of the problem.
Minnesota river here is basically a green vegetative version of the Grand Canyon. Carved 200 feet down into the clay subsoils. It meanders in oxbows across the valley bottom.
50 years ago that rich river bottom was farmed and hayed and pastured. It flooded 2 out of 4 years, but the good years paid well and purchase price and taxes reflected the 3/5 value.
All to say, it was a a smooth unobstructed river valley. When it flooded the water moved on by, flowed along and emptied.
Now 50 years later, the dnr bought up much of the land, restricted the use of the rest of it, and govt program easements took up most of the rest of it. Maybe only 15% of it is actively farmed compared to 50 years ago.
What grew up? Scrub trees. We live on the prairie, but creek and ravine and rivers are extremely tree lined here. The whole river valley is a scrub Forrest now. Hundreds of thousands of tree trunks, and broken down elm and ash trees.
When it floods and the river is a mile wide, it barely flows. All those tree trunks and debris really puts the brakes on water flow. Now it piles up water, instead of flowing on downstream.
Then number two, 50 years ago my town had one main highway across the river. Two small county roads crossed also, both were very low roads that flooded every spring. A mile wide water flowed over the tops of the roads moving on down. The main river crossing topped over in the 90s, allowing water to flow down the river.
Now the county roads were rebuilt to 25 and 50 year flood heights, new bridges. The main highway was also rebuilt and raised 8 feet.
Any flood water coming down the river now has to funnel under those 3 bridges, whatever span they have, instead of the mile wide the river used to flood to.
So the water has to pile up higher, because it can’t flow as wide as it used to. More bridges, higher road beds, thousands of trees.
Multiply that up and down the river, at every town…..
And still, the water flood heights of the mid 1960s are in place in many parts of the river.
Paul | |
|
Building the world's largest drainage ditch
