Letter: Lessons learned from Central Indiana flooding
Recently, multiple days of heavy rainfall have caused unprecedented flooding in the Indianapolis area. Why was there so much flooding?
Areas near Indianapolis received up to 11 inches of rain. That is 298,694 gallons of water per acre of land. Since the area is so highly developed, most of that water was runoff, causing the storm sewers, ditches, streams, and rivers to be overwhelmed, resulting in flash flooding.
What would happen if a similar rain event occurred in Dubois County?
Dubois County currently has approximately 160,000 acres of farmland (64%), compared to 14,600 acres in Marion County (7%) (USDA). Farmland acts as a sponge. Loamy soils can hold about 2.5 inches of water per foot, and most Dubois County, the soil is 20 to 36 inches to the hardpan (Purdue University). Assuming an average depth to hardpan of two feet, that is 5 inches of water absorbed per acre, or 135,770 gallons.
Where does the other 162,924 gallons go? It runs off the land. Most will be handled by the streams emptying into the Patoka and White Rivers. There is about a 150-foot drop in altitude between Patoka Lake and where the Patoka River meets the Wabash River, meaning most of the water will flow relatively quickly out of the county. It would still likely exceed the capacity of the streams and rivers in the short term, causing the water to back up into the floodplain. Outside of a few areas in Jasper, there is little development along the river, so most of the floodplain would not result in structural damage, mainly crop damage and the usual roads being closed.
Dubois County is very well situated to avoid the type of damage they have seen in Indianapolis because we still have nature’s defense in place. Every acre of farmland destroyed by industrial and residential development increases the potential runoff due to lessening the sponge effect of open land. Restricting the flow of water by placing artificial bottlenecks like a road through the floodplains increases the time it takes the runoff to move downstream and out of the county. Development that fills in the floodplains gives the water less room to spread out and stay out of the cities and towns.
Farmland is more than a place to grow crops. It is also our protection against more serious flooding in urban areas, nature’s air and water purifier, and the home to the wide variety of wildlife we have in this county. It is shortsighted to allow it to be destroyed in the pursuit of profit. Farms are essential part of living a good life in both the cities and the country. We should be doing everything we can to protect them.
Tom Bartelt
Huntingburg
