The need for recognition and implementation of a sinkhole-floodplain hazard designation in urban karst terrains

Soluble rock terrains pose increased flood hazards because of a demographic shift from the upper Middle West and metropolitan Northeast to the “Sun Belt.” Approximately one-half of the soluble rock terrains in the continental United States occur in the Sun Belt. Urbanization of karst terrains generally increases the frequency and magnitude of sinkhole flooding and the probability of collapse. Soil erosion attendant with urbanization results in silt deposition in depressions, reducing sinkhole runoff storage capacity and regolith hydraulic conductivity. A new flood-hazard designation termed the sinkhole flood-plain is advocated for use by federal mortgage agencies in karst terrains so that sinkhole-related flooding can be minimized. A four-phase methodology for assessing sinkhole flood hazards in a rapidly urbanizing karst terrain is developed, using examples from central Tennessee and southern Kentucky.