The Sliding City
Cincinnati is flooded by the Ohio River once again; the flood gates close as the water rises. In the month of February, it rained a total of 16 times, yielding a total of 7.8 inches of water across the city. Much of the water went through the drainage and sewers to be mostly dumped into the Ohio River. There are 1,350 discharge points for overflowing water to be dumped into the river, and this caused the Ohio River to flood.
Another contributing factor to the flooding is the three bodies of water that run into the Ohio river: the Licking River, Little Miami, and Mill Creek. The rain that affects the Ohio River also affects the three smaller ones and so the amount of water is three times as apparent.
The amount of rain in Cincinnati is due to the movement of the polar vortex. While Cincinnati is somewhat in the northern part of the country, we have undocumented high temperatures in the past three years. The average temperature for last year was 55 degrees. This year alone, there was a day that had 5.02 inches of rain. The last time that record precipitation was surpassed in one day was 1964. In 2018 it rained 137 days out of the year, that is more than most cities in the country. This makes Cincinnati the 8th wettest city in the country by this measure.
All this rain has effected the field capacity of the soil. Field capacity is the amount of water soil can contain until it can't soak up and it starts to pool and to run off.
Cincinnati is surrounded by the Ohio River on its south and by hills on its north. The seven hills of Cincinnati span from the east bank of the river to the west bank, in a crescent shape. The hills include Mount Adams, Walnut Hills, Mount Auburn, Vine Street Hill, College Hill, Fair mount and Mount Harrison. All these hills funnel water to through the city and into the river. When it precipitates an extensive amount, the field capacity becomes filled and water begins to run off the hills. The water will still be soaked up but flows to a point that it is no longer able to be drained; such as clay. The combination of the steep hills and the increase of water, landslides have become more frequent. The top six feet of soil slide on top of the slick clay or limestone underneath.
The City Responds
The way the city manages the flooding and landslides are described by Mr. Kurt Kastner, who is an Urban Forester for the city of Cincinnati. He works closely with the city ‘s landslide engineer, who is responsible for all programs that are involved with the damages, responses, and prevention for the city. Mr. Kastner would be called to go out and cut trees that were displaced by the landslides. The latest landslide was “pretty big” as Mr. Kastner recalled while he was working on site. He estimated that the damages from that one large landslide was 250,000 dollars, that is for the labor that must clear out the soil and debris; this process could take up to three days. This is considered overtime, because Cincinnati doesn't have a public service specifically dedicated to landslide cleanup.
Cleanup usually involves a large band of trucks and an excavator to take the excess soil to a contractor to store it. They intentionally do not take all the debris because that would leave a new space for another landslide. Instead they use the actual landslide as natural barrier for future landslides.
With the increase of precipitation in the areas in and around Cincinnati, the city has some ideas to prepare for this new threat. While they will still use the response method to deal with landslides in Cincinnati, the city will have strict permits and soil tests to investigate if it is sustainable and safe to build in certain areas in the future. The typography of the hills in Cincinnati are the focus for prevention and improvement. When the soils and clay are moved then it becomes a man made problem that is only exasperated by the rain.
A department now having growing influence in this problem is the Metropolitan Sewage District. They are trying to slow the flow of water to the creeks that feed into the river. A cost effective and maintenance-free solution that only needs to be installed is Topmix Permeable. This is fast drying concrete that absorbs water. It then distributes the water to reservoirs or lets the water naturally flow underground. This method of slowing down run off saves the city money. That is because the city would have too store, clean, and transport the water that would be in surplus already.
The City of Cincinnati is continually evolving with the changing climate and is always on watch for when the next part of the city inevitable experiences more floods and landslides.