Monday, August 1, 2016

Mapping Disaster


What is revealed when 1913 high-water measurements are input into today’s Geographic Information System (GIS) computational tools? By guest author Barry Puskas of the Miami Conservancy District

[Note October 2, 2016: I am in the process of moving both my office and household 40 miles away. As a result of the inevitable chaos, my next post will be November 1. Thank you for your understanding. - T.E.B.]

Beginning Easter Sunday 1913, 9 to 11 inches of rain fell within three days, March 23–25, throughout the Great Miami River watershed. The massive deluge surged through downtown Dayton and a host of other cities and towns, 
Dramatic digitized map of 1913 flood depths in Dayton, Ohio, was one of nine geo-referenced maps created by Barry Puskas and colleagues at the Miami Conservation District (MCD) between 2008 and 2012, synthesizing data from 1915 hand-drawn maps with modern GIS techniques. For this poster, which also paired photographs of submerged locations in Dayton with similar views of the same locations today, Puskas was received the Map Gallery People’s Choice Award from the Ohio GIS Conference (OGISC) of 2013. High-res digital maps of the 1913 flood in Dayton and eight other cities are available from the MCD (more info below)
drowning or otherwise killing more than 360 people throughout the Miami Valley—60 percent of Ohio’s death toll in just 10 percent of its area. In addition, property damage throughout just that southwestern corner of Ohio exceeded $100 million in 1913 dollars, equivalent to between $2.5 billion and $44 billion in today’s economy (see the discussion at the end of this post on converting the value of historical dollar figures, as well as details about fatalities in “’Death Rode Ruthless…’” and about property damage in “Like a War Zone).

This slide and others like it are courtesy Barry Puskas, Miami Conservancy District

In response to the flood, the some 23,000 citizens of the Miami Valley raised local donations of $2.2 million (in 1913 dollars) by the end of May for a permanent flood protection system (see “Morgan’s Cowboys). The Miami Conservancy District (MCD) was formed as a regional agency for the entire watershed; construction was finished in 1922 and the system completely paid for 1949 (see “Morgan’s Pyramids). The MCD has been providing flood protection since. 

The MCD system consists of five major dry dams (slide 14) that hold back floodwaters in excess of what can be handled by 55 miles of levees and 35 miles of improved channel downriver. The system protects not only Dayton but
The Miami Valley is the land area surrounding the Great Miami River in southwest Ohio that encompasses about 10 percent of the area of Ohio. This area suffered 60 percent of the state’s deaths in the massive 1913 flood and close to half its property damage.

also select areas in the cities of Franklin, Hamilton, Huber Heights, Miamisburg, Middletown, Moraine, Piqua, Tipp City, Troy, and West Carrollton.

The system was designed to protect the valley from not just another 1913-scale flood but also an additional 40% more runoff. The 1913 flood exceeded a 500-year flood (that is, one with only 0.2 percent chance of occurring any year), and some statistics I’ve seen indicate it even exceeded a 1000-year flood (one with less than 0.1 percent chance of occurring any year). So the MCD system protects the valley against a 1000-year flood plus potentially 40% more. That’s a heck of a lot of flood protection.  But after suffering through the 1913 flood, the citizens of the Miami Valley did not and do not want to experience such a catastrophe ever again.


Need for maps

To design, engineer, and construct the effective dams, levees, and improved channels, MCD engineers needed several sets of data including: 1) detailed topographic information of the cities and rural regions swept by the flood; 2) the actual peak heights and extent of the floodwaters for calculating the volume and forces exerted; and 3) some realistic sense of the probability of a future flood of the same or greater magnitude for calculating an adequate safety margin.
 
But in 1913, only 1:62,500 scale U.S. Geological Survey topographic maps existed of the Miami Valley. Those USGS maps were of only limited use, however, as the usual USGS elevation contour interval was 20 feet, far too coarse mapping of elevations for the MCD’s flood-protection needs.
Just months after the Great Easter 1913 Flood, Arthur E. Morgan, founder of Morgan Engineering Co., deployed 50 engineers around the Miami Valley watershed to calculate the actual volume of water in the 1913 flood. In the absence of reliable maps, Morgan’s men—some dressed as cowboys—went house to house interviewing residents to record the times of flood stages, and surveyed the land themselves. The goal: to deduce the maximum possible flood and engineer fix-it-forever flood protection for Dayton. [Photo credit: Miami Conservancy District]

So, to gather the additional data, MCD chief engineer Arthur E. Morgan famously sent teams of surveyors armed with buckets of white paint fanning out throughout the Miami Valley, interviewing residents about flood heights and times, marking flood heights on buildings and trees with white paint all the way from Piqua (pronounced PICK-wah) to Hamilton.
 
Then, using traditional surveying tools and techniques, they meticulously measured horizontal lines of sight and (vertical) elevations. They determined elevations to 1-foot contour intervals on flat ground for the whole river corridor where it flooded, and 2-foot intervals on steeper slopes up to 50 to 75 feet elevation above the flood zone. 

By 1915, they completed about 100 hand-drawn, black-and-white paper maps of the valley’s topography and high-water marks plus property boundaries and other essential features. The contour maps included topographical information, 1913 flood limits, and observed high water marks. In some areas, they even mapped river bottom elevations that would have been below the water’s surface. The maps were so careful and precise that they were used by the MCD for nearly a century for estimating flood depths.
 
Bringing the maps into the digital age
Beginning in 2008, the MCD wanted to digitize the maps so that they could be geo-referenced to a modern geographic coordinate system where the data could be manipulated using computerized Geographic Information System (GIS) methods. By 2012—in time for the centennial of the Great Easter 1913 Flood—the MCD produced dramatic new maps of the 1913 flood. 

The new digital maps are scientifically important, because much topography today has been altered from what it was in 1913 as a result of major changes—including construction of the MCD flood protection works themselves. The new maps would allow us to overlay the current MCD levees and channel improvements. Making the maps digitally accessible also would allow us to understand some of the dynamics of the 1913 flood in greater detail as described by observers or survivors. 

The new digital maps are also historically and culturally important. Mapping the 1913 flood over today’s geography brings home to current residents the phenomenal extent and power of the natural disaster against modern landmarks. Thus, the maps may be freely used by historical societies and other groups throughout the Miami Valley. A few communities—notably 

Large (9 x 21 inches) utility-grade stickers are available from the Miami Conservancy District for communities wishing to commemorate 1913 flood heights. Credit: Sticker courtesy Barry Puskas, MCD; photo by Trudy E. Bell

Dayton, and Franklin, Hamilton, and Troy—have chosen to use the maps to guide them in prominently marking the peak flood heights of the 1913 flood along downtown streets to encourage walking tours of local history. To that end, the MCD also produced utility-grade stickers that can be affixed to light poles and other smooth surfaces to mark 1913 high water.

Converting from then to now
In a nutshell, the MCD generated the new digital maps from the century-old paper maps. As just one example, I’ve zoomed into one area in Piqua: a peninsula jutting into the Great Miami River that we dubbed the Piqua nose, which shows the hand-drawn streets as they existed in 1913. 

First, we took the black-and-white maps and raster-scanned them to convert them into digital form. Then we digitally stitched them together to give us one gigantic map of the entire Miami Valley, through all five counties along the Miami River corridor. To tie them to modern geographic reference systems—specifically to the Ohio State Plane coordinates—we needed features that have not changed since 1913. Streets are sometimes dug up and moved, buildings razed, canals filled in or otherwise destroyed, bridges replaced, etc. But in general, railroad tracks don’t shift much. So the railroad tracks were essential in allowing us to carefully tie the century-old maps to today’s widely used coordinate system.

We also wanted to separate out the topographic contour intervals along with their associated elevation information. We did that through what is known as a raster-to-vector conversion, which simply means converting a hand drawn line from an image to a digital (or computerized) line object. 

That allowed us to create a digital elevation model (DEM) of the region’s topography in 1913, extracting three-dimensional information from the two-dimensional maps. That’s important because water runs downhill—river hydraulics is all about topography and gravity—and features obstructing floodwater flow that can change or alter flow patterns and flood depths.

On that 1913 digital elevation model, we were then able to plot all the high water marks that Morgan’s surveyors had painted and measured—shown as red dots. They plotted and recorded some 1,900 high water marks along the river corridor. 

Then, from those high-water marks, I made some flood water surface lines, that is, making lines that would represent the maximum or peak surface of the 1913 floodwater from one side of the river valley to the other. 

Now here comes the power of digital manipulation. The digital 1913 flood water surface was interpolated to map the edge of the flood boundary.In addition, the data were used to calculate flood depth for every 10 foot by 10 foot area on the ground. The detailed depth mapping was a new look of the flood that depicted much more detail than the 1915 maps. The newly created flood boundary from GIS matched very well to the 100-year-old paper maps; even the dry areas, or as I call them "islands," complemented the original maps.

From this stage, we can now display today’s aerial imagery view of Piqua’s city streets to create a flood depth map for the city and whole region. Once again picking on Piqua, this view reveals how the 1913 floodwaters—which were up to 20 feet deep in this region—would have inundated the streets of Piqua as they exist today. This, of course, is what happened before the MCD flood protection system was built.

Equally dramatically, now that everything is georeferenced, we can digitally superimpose other layers from current aerial photography or any other digital information. For example, we can overlay the MCD’s current flood protection measures: the long orange line around the Piqua nose marks the MCD levees, and the little green squares mark some floodgates on storm sewer outlets so water can’t get back underneath the levees and inundate the city. 

Finally, we can map the area of Piqua—or elsewhere along the Great Miami or other rivers—now protected by the MCD system today.

Sidebar: Gallery of digitized maps
Below are thumbnail images of the digitized maps of the 1913 flood depths in eight cities along the Great Miami River corridor, in addition to the map of Dayton shown as the lead (top) photo in this article. High-resolution versions of the maps are available from the Miami Conservancy District, especially for those communities that wish to create exhibits or otherwise commemorate the 1913 flood as part of their local history. For more information about the digitized maps and high-water stickers, contact the author Barry Puskas c/o t.e.bell@ieee.org.
Digital map of 1913 flood in Franklin, Ohio. Credit: Miami Conservancy District
Digital map of 1913 flood in Hamilton, Ohio. Credit: Miami Conservancy District
Digital map of 1913 flood in Miamisburg, Ohio. Credit: Miami Conservancy District
Digital map of 1913 flood in Middletown, Ohio. Credit: Miami Conservancy District
Digital map of 1913 flood in Moraine and West Carrollton, Ohio. Credit: Miami Conservancy District
Digital map of 1913 flood in Piqua, Ohio. Credit: Miami Conservancy District
Digital map of 1913 flood in Troy, Ohio. Credit: Miami Conservancy District
Digital map of 1913 flood north of Troy, Ohio. Credit: Miami Conservancy District
Barry Puskas, P.E., G.I.S.P.—shown here with the Map Gallery People’s Choice Award he received at OGISC 2013—has been manager of technical services for the Miami Conservation District in Dayton, Ohio, since 2007. Before that, he was a hydrologist for the U.S. Geological Survey. Mr. Puskas has professional experience in civil engineering projects such as land development design, hydraulic and hydrologic studies, and dam/levee safety engineering. A graduate of The Ohio State University, he is a registered professional engineer (PE) and geographic information system professional (GISP). His technical expertise is in hydrologic and hydraulic modeling; FEMA flood studies; geographic information systems; flood forecast modeling; flood protection system operations; and engineering design and analysis of dam safety and levee safety projects. Mr. Puskas also has experience in management of information technology (IT) including servers, virtual servers, network systems, work stations, laptops, and mobile devices. He may be reached c/o t.e.bell@ieee.org.

©2016 Barry Puskas

Next time: Racing Against Epidemic

Selected references
The text and most of the illustrations in this guest post are based on half the conference presentation by Barry Puskas supplemented with information gathered during a telephone interview with him on June 24, 2016. Listening to his full 45-minute presentation online while watching his full slide presentation is highly recommended for his additional discussion comparing photographs taken during the 1913 flood in half a dozen cities with photos of the same locations today.

There are at least seven separate methods for assessing the present value of historical money (all seven are discussed at the excellent site MeasuringWorth.com by two economics professors at the University of Illinois). They are all correct in different contexts, yet they all yield answers that differ widely. Since natural disaster losses pertain to damage to and rebuilding major projects such as bridges and railways, the most relevant method for this purpose seems to be the “relative share of the GDP,” which allows comparison of the cost of construction of a major project in historical times to the value in the economy at the time as a percentage of the GDP. To compare capital losses in 1913 dollars with 2014 dollars (the latest given on Measuring Worth.com), the “relative share of the GDP” calculator multiplies 1913 dollars by a factor of 439 to reach today’s value. So $100 million in 1913 would translate to about $44 billion today

For more information, see Officer, Lawrence H. and Samuel H. Williamson, “Measuring Worth is a Complicated Question”; for the actual calculator, see “Seven Ways to Compute the Relative Value of a U.S. Dollar Amount, 1774 to Present.” See also their discussion “Choosing the Best Indicator to Measure Relative Worth,” using the cost of constructing the Empire State Building as an example.  

Miami Conservancy District, The. A Flood of Memories. One Hundred Years After the Flood: Images from 1913 and Today. The Miami Conservancy District. 2013. ISBN 978-0-615-75860-2. 128 pages. Hardbound. Colorful coffee-table book depicts the dramatic 1913 flood side-by-side with images of the same areas today captured by photographer Andy Snow. Dayton, Franklin, Hamilton, Miamisburg, Middletown, Piqua, Troy, and West Carrollton are all included. Each pair of images has brief descriptive text, but the bulk of every page is reserved for the striking contrasts between devastation in 1913 and the safety and vibrancy these communities enjoy now.

Some two dozen more books plus several documentary films have been published about the 1913 flood in various cities in the Miami Valley, including many for the 2013 centennial commemoration. For detailed listings and descriptions of them, see “Book Report!”, Centennial Highlights—and Legacy, “Centennial Year + 2, and “1913 Flood + 3.

Bell, Trudy E., The Great Dayton Flood of 1913, Arcadia Publishing, 2008. Picture book of nearly 200 images of the flood in Dayton, rescue efforts, recovery, and the construction of the Miami Conservancy District dry dams for flood control, including several pictures of Cox. (Author’s shameless marketing plug: Copies are available directly from me for the cover price of $21.99 plus shipping, complete with inscription of your choice; for details, e-mail me.)

 

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