THE FLOOD REPORT
The Flood of June 7, 2008
Contributing Factors, Effects on Franklin, and Resources for the Future
by Gary W. Moody
Sept. 6, 2008
Updated (& still in progress) June 7, 2009.
THE FLOOD OF JUNE 7, 2008 - photos
Flooding occurs when a watercourse is unable to convey the quantity of runoff flowing downstream. The frequency with which this occurs is described by a return period. Flooding is a natural process, which maintains ecosystem composition and processes, but it can also be altered by land use changes such as river engineering. Floods can be both beneficial to societies or cause damage. Agriculture along the Nile floodplain took advantage of the seasonal flooding that deposited nutrients beneficial for crops. However, as the number and susceptibility of settlements increase, flooding increasingly becomes a natural hazard. Adverse impacts span loss of life, property damage, contamination of water supplies, loss of crops, and social dislocation and temporary homelessness. Floods are among the most devastating of natural disasters.
On June 7, 2008, Johnson County and neighboring areas experienced the worst flooding in recent history. In Franklin, at least, it was the worst flooding since 1913. The July 1 edition of the Daily Journal called it a "1000-Year Event." In addition to rain during the preceding week, Franklin received 8.05 inches of rain from June 6 to June 7. The cumulative rainfall in the Youngs Creek watershed caused a peak flow on June 7 of 20,500 cubic feet per second, about 500 times greater than the average flow, and more than the median flow rate of the Wabash River, which is 17,000 c.f.p.s at its widest point. (All data from the Journal article.)
Various natural and man-made factors were involved in the severity of the flooding, as outlined in the five points below. Most of these points are related to Franklin, but also involve the surrounding watershed, as well as matters of government and regulation at the local, state, and national levels.
First: As is the usual case with floods, the area received a large amount of rain in a short period of time. Which is, unless climate change is a factor, a natural process we have no control over.
Second: Facts on the ground, so to speak, determine how the floodwater effects the community. Franklin happens to be at the confluence of several streams, in sort of a bulls-eye situation, impacted by flows from the northeast and the west. Decisions that were made on drainage in the early days of the community need to be re-assessed, and new solutions added; not only as to city drainage systems, but also major flood control engineering.
Third: Development upstream of Franklin has had a major impact on the amount and speed of stormwater runoff that heads our way. The most heinous example that I am aware of is Windstar 2, to which I devote two pages in my report.
Fourth: Antiquated concepts, old wives' tales, and outright ignorance have all been applied to the mis-management of local streams and drainage ditches. In fact, streams have been turned into ditches. These practices are contrary to what science tells us we should be doing to mitigate runoff and flooding, and I am suggesting that these practices contributed to the June disaster. Nevertheless, we are still hearing calls to denude banks and straighten channels. To stretch the point, Johnson County is not Vietnam in the 1960's, and streams and their natural environments are not the Viet Cong, to be blasted and put in constraints.
Fifth: By studying the reports and recommendations of scientists and other experts (Purdue Extension, for example), we can determine what we've been doing wrong, prevent further damage, and repair that which has been made. The latter has been at great expense, and repairing that will involve additional expense. But the officials who have been given the public's trust and checkbook need to turn things around, because our communities need to be assured that officials are moving forward to prevent or at least mitigate future events such as that of June 7, 2008.
FIVE FACTORS IN FLOODING
1. Too much rain - Uncontrollable factor at present.
2. Site location, topography, and drainage.
Franklin flooding: Reasons and Solutions.
3. Poor land use practices.
LAND USE AND FLOODING
Franklin's Windstar Subdivision: An Environmental Disaster
LEGAL RAMIFICATIONS OF THE WINDSTAR DEBACLE
4. Poor stream management practices.
IMPROPER STREAM MANAGEMENT
5. Solutions and Nature.
BENEFITS OF TREES/EFFECT ON FLOODING
A BELATED THANK YOU TO AND ACKNOWLEDGEMENT OF
THOSE WHO HELPED COMPILE THIS INFORMATION, especially:
JOHNSON COUNTY MUSEUM LIBRARY DEPT.
SAM CARMAN, Education Director, IN DNR
KIMBERLY ROBINSON, Purdue University, Dept. of Forestry and Natural Resources
JENNY JOHNSON, Digital Initiatives Project Coordinator, IUPUI University Library