Flooding events are major natural hazards that present significant risk to communities worldwide. Calculations of flood recurrence rate through time are important tools for regulating land use, determining insurance rates, and for the design and construction of levees and dams. Typically, flood recurrence rates are based on limited historical data or on evidence preserved in the geologic record as overbank deposits, tree ring scars, or high water scour marks. However, these approaches are either limited in their ability to produce continuous time series of flooding events or do not consider the effects of regional land use change. Here we use scanning superconducting quantum interference device (SQUID) microscopy to rapidly image the magnetization associated with flood layers in a polished surface of an annually laminated stalagmite from Spring Valley Caverns (SVC) in southeastern Minnesota. A time series of magnetization peaks, each of which corresponds to a flooding event, yields an average flood recurrence rate of ≤5 events per century for the last 500 years. This rate increases to ∼7 events per century since 1900, coincident with historical timber and agricultural land-use changes in Minnesota. This approach produces a continuous record of well-dated, extreme-precipitation events that can be examined within the context of land use change.
Bibliographical noteFunding Information:
This work was financially supported by US National Science Foundation grant EAR-1316385 and through a University of Minnesota Grants-In-Aid award and a McKnight Land-Grant Professorship awarded to JMF. EAL and BPW would like to thank the National Science Foundation grants DMS-1521765 and DMS-0934689 for partial support. We thank John Ackerman, the owner of Spring Valley Caverns, for access to, and his continued support of research in Spring Valley Caverns. We are grateful for comments by Andrew Roberts, Plinio Jaqueto, and an anonymous reviewer. This is IRM contribution 1309.
© 2019 Elsevier B.V.
- flood recurrence
- mineral magnetism
- scanning SQUID microscopy