2010 Metro Mitigation Plan

FLOOD
Risk – High; Vulnerability – High
Flooding impacts may include urban, residential, and commercial consequences. Buildings
can experience significant damage, sometimes beyond repair. Household furnishings and
business inventories can be lost if there is not adequate time to remove items to safe locations.
Subsequent impacts include revenue loss to employees and businesses, as well as, local
governments through tax loss.
In addition to being at risk because of floodwater, residents face the threat of explosions and
fires caused by leaking gas lines along with the possibility of being electrocuted. Even wild
animals, such as venomous snakes, forced out of their homes and brought into contact with
humans by floodwaters, can be a threat. Additional public health concerns include mold,
West Nile Virus, and encephalitis.
Severe flooding can cause extensive damage to public utilities and disruptions to the delivery
of services. Loss of power and communications can be expected. Drinking water and
wastewater treatment facilities may be temporarily out of operation. Storm and sanitary
sewers may also be impacted due to locations in floodprone areas for design purposes, such as
gravity flow to minimize pumping charges.
Impacts of flooding on transportation are particularly significant. Flooded streets and roads
block transportation and make it difficult for emergency vehicles to respond to calls for
service. Floodwaters can washout sections of roadway and bridges. This disruption may
extend to a regional, even national, scale particularly with regard to access to highways,
railroads, and navigable waterways. Most importantly, the majority of fatalities that occur in
floods are the result of people trying to dry on roads covered by floodwaters.
In order to determine vulnerability, the 100-year floodplain map was overlaid onto the Metro
parcel data. The properties that intersected the floodplain were then queried for property
improvements greater than $0.00. Improvement values are tied to the parcel data, not to
building footprints. This gave an indication of an improvement to a piece of property that
touched the floodplain, i.e. count of structures in floodplain. There are approximately 12,040
parcels that intersect the floodplain with an improvement value greater than $0.00. These
properties represent approximately six percent of the properties of Metropolitan Nashville and
Davidson County (Table 4-30).
Twenty-two critical facilities, as defined by the Office of Emergency Management and the
Metropolitan Police Department, are located within the floodplain. These facilities include:
St. Thomas Hospital;
Metro Police Department South Precinct;
Omohundro Drive Water Treatment Plant;
County Government Complex;
Whites Creek High School;
Nashville State Technical Institute;
Metropolitan Nashville - Davidson County
Vulnerability Assessment
Multi-Hazard Mitigation Plan Page 4-87
April 2010