The Plant City, Fl, “sinkhole swarm”: using current events to teach Earth Science

1. The Plant City, Fl, “sinkhole swarm”: using current events to teach Earth Science William Parker Earth, Ocean and Atmospheric Science, FSU with assistance from FDEP-FGS archived: http://quartz.gly.fsu.edu/~parker/DestinTalk.pptx

2. Week of January 10, 2010 • Temperatures in Florida dropped to record lows • Wells in Dover/Plant City area recorded water level drops of up to 60’ (lowest levels since recording started) • Over 140 sinkholes formed, most in Dover/Plant City area • Over 600 dry wells reported to SWFWMD

3. DEP-FGS DEP-FGS DEP-FGS

4. DEP-FGS US-27, DEP-FGS CR 630, DEP-FGS

5. Florida may be the “Sinkhole Capital of the US” …

6. However the formation of sinkholes is not entirely unrelated to human activities. Study of “sinkhole swarms” can be an effective way to introduce students to earth science concepts, and to explore how these concepts impact such things as population growth, agriculture and politics.

7. KARST Limestone or Dolostone H2O + CO2 = H2CO3 Carbonic Acid

8. Karst areas in the US Requires water and limestone near surface

9. Karst in Florida

11. Types of Sinkholes: Dissolution Tihansky, 1999

12. Types of Sinkholes: Cover Subsidence Tihansky, 1999

13. Types of Sinkholes: Cover Collapse Tihansky, 1999

17. Dover- Plant City WEST EAST

20. Sinkholes can be induced by drawdown (pumping) of aquifer or by heavy rains saturating the surface cover

21. Groundwater and Development

24. Freeze of 2010 – Strawberry Farmers pumped over a billion gallons of water per day for seven days, trying to save their crops. Aquifer water levels plummeted. Chip Litherland

27. Sinkholes formed in and around the strawberry farms.

31. The crop saved should have had a value approaching $300 million… Jay Nolan, Tampa Tribune

32. But … The cold delayed ripening such that the whole crop ripened at once, driving down the price of the fruit and making it uneconomical to pick.

33. Meanwhile… Sinkhole insurance claim numbers for 2010 have topped 600, with a total value expected to be around $500 million. But, could we have predicted this?

34. The Great Freeze of 1977 – Temperature in Hillsborough dropped below freezing for 5 consecutive nights.

36. The Great Freezes of 1983 & 1985 – Temperature in Hillsborough dropped below freezing for 3 consecutive nights.

37. The 1983 freeze produced few sinkholes, possibly because the Frost Warning Service failed to forecast it and much of the fruit was lost before pumping could start. Therefore water table drawdown was limited. The 1985 freeze produced a maximum drawdown of 40-55 feet over a limited area and triggered at least 27 sinkholes.

38. Hillsborough Co. sinkholes for the period 1964 – 1992 Illustrating seasonal peaks in induced sinkhole formation.

39. FGS Sinkhole Database entries for Hillsborough Co., Dec-Feb only FSRI funding cut

45. SWFWMD Dover/Plant City Freeze Management Plan • Declaring a 256-square-mile water use caution area in the Dover/Plant City area • Establishing a Minimum Aquifer Level and Minimum Aquifer Level Protection Zone • Developing a recovery strategy to help meet the Minimum Aquifer Level • Expanding the FARMS Program and increasing incentives for alternative frost/freeze protection methods • Requiring automatic meter reading devices • Creating a new process for allocating dry well complaints • Expanding the area where special well construction standards apply • Expanding the data collection network for freeze events • Enhancing communication for freeze events

46. Is it all Fraud? Sinkhole claims are where you would geologically expect them to be.

47. Wilson and Beck (1992) discovered that rate of sinkhole formation is directly related to amount of drawdown FSRI funding cut

48. Although some fraud undoubtedly exists, at least part of the driving force behind the increase in claims due to • an increase in population, • a shift of population into previously agricultural areas, and • an increasing demand for groundwater.

49. What should we have learned • Human removal of groundwater does dramatically influence sinkhole formation in some areas. (Human behavior affects Earth processes). • In sensitive areas demands for groundwater should be balanced with probable adverse outcomes. (Integration of political, agricultural, and societal pressures with scientific understanding). • Changing population and agricultural demands may cause current and future outcomes to be substantially different from the past. (Optimal solutions rarely remain fixed).

50. Bengtsson, T.O, 1987, The hydrologic effects from intense ground-water pumpage in east-central Hillsborough County, Florida, in Beck, B.G., and Wilson, W.L., eds., Karst hydrogeology: Engineering and environmental applications: Proceedings of a conference sponsored by the Florida Sinkhole Research Institute, February 9-11, 1987, College of Engineering, University of Central Florida, Orlando: [Boston, Mass., Balkema, A.A.], p. 109-114. Fleury, Spencer, 2009, Living on Limestone: Land Use Policy and Practice in Karst Terrains. Springer, 187 pp. Florida Geologic Survey, Subsidence Incidence Reports, http://www.dep.state.fl.us/geology/gisdatamaps/SIRs_database.htm Metcalfe, S.J., and Hall, L.E., 1984, Sinkhole collapse due to groundwater pumpage for freeze protection irrigation near Dover, Florida, January 1977: Multidisciplinary Conference on Sinkholes, 1st, Orlando, Fla., October 15-17, [Proceedings, Beck, B.F., ed., Sinkholes--Their geology, engineering and environmental impact: Boston, Mass., Balkema, A.A.], p. 29-33. Tihansky, A.B., 1999, Sinkholes, west-central Florida, in Galloway, Devin, Jones, D.R., Ingebritsen, S.E., eds., Land subsidence in the United States: U.S. Geological Survey Circular 1182, p. 121-140. Wilson, W.L., and Beck, B.F., 1992, Hydrogeologic factors in affecting new sinkhole development in the Orlando area, Florida: Ground Water, v. 30, no. 6, p. 918–930.