ANNEX B DESOTO COUNTY

Transcription

1 ANNEX B DESOTO COUNTY This annex includes jurisdiction-specific information for DeSoto County and its participating municipalities. It consists of the following five subsections: B.1 DeSoto County Community Profile B.2 DeSoto County Risk Assessment B.3 DeSoto County Vulnerability Assessment B.4 DeSoto County Capability Assessment B.5 DeSoto County Mitigation Strategy B.1 DESOTO COUNTY COMMUNITY PROFILE B.1.1 Geography and the Environment DeSoto County is located in north western Mississippi. It comprises one town and four cities, City of Hernando, City of Horn Lake, City of Olive Branch, City of Southaven, and Town of Walls, as well as many small unincorporated communities. An orientation map is provided as Figure B.1. The county is located to the east of the Mississippi River and north of Arkabutla Lake. The total area of the county is 497 square miles, 21 square miles of which is water area. Summer temperatures in the county range from highs of 90 degrees Fahrenheit ( F) to lows in the 60s. Winter temperatures range from highs in the low to mid 50s to lows in 30 F. Average annual rainfall is approximately 53 inches, with the wettest months being May and December. B:1

2 FIGURE B.1: DESOTO COUNTY ORIENTATION MAP B.1.2 Population and Demographics According to the 2010 Census, DeSoto County has a population of 161,252 people. The county has seen an increase in population between 2000 and 2010, and the population density is 324 people per square mile. Population counts from the U.S. Census Bureau for 1990, 2000, and 2010 for the county and participating jurisdictions are presented in Table B.1. Jurisdiction TABLE B.1: POPULATION COUNTS FOR DESOTO COUNTY 1990 Census Population 2000 Census Population 2010 Census Population % Change DeSoto County 67, , , % Hernando 1,158 6,812 14, % Horn Lake 2,965 14,099 26, % Olive Branch 1,322 21,054 33, % Southaven 6,115 28,977 48, % Walls , Source: United States Census Bureau, 1990, 2000, and 2010 Census B:2

3 Based on the 2010 Census, the median age of residents of DeSoto County is 35 years. The racial characteristics of the county are presented in Table B.2. Whites make up the majority of the population in the county, accounting for 72 percent of the population. Jurisdiction TABLE B.2: DEMOGRAPHICS OF DESOTO COUNTY White, Percent (2010) Black or African American, Percent (2010) American Indian or Alaska Native, Percent (2010) Asian, Percent (2010) Native Hawaiian or Other Pacific Islander, Percent (2010) Other Race, Percent (2010) Two or More Races, percent (2010) Persons of Hispanic Origin, Percent (2010)* DeSoto County 72.2% 21.9% 0.3% 1.3% 0.1% 2.8% 1.6% 5.0% Hernando 81.6% 13.1% 0.2% 1.0% 0.0% 3.0% 1.1% 5.5% Horn Lake 59.0% 32.9% 0.4% 1.0% 0.0% 4.5% 2.3% 8.0% Olive Branch 71.5% 23.1% 0.2% 1.3% 0.1% 2.4% 1.4% 4.2% Southaven 71.0% 22.2% 0.3% 1.7% 0.1% 3.0% 1.7% 5.0% Walls 34.7% 60.8% 0.2% 0.6% 0.0% 1.4% 2.3% 3.0% *Hispanics may be of any race, so also are included in applicable race categories Source: United States Census Bureau, 2010 Census B.1.3 Housing According to the 2010 U.S. Census, there are 61,634 housing units in DeSoto County, the majority of which are single family homes or mobile homes. Housing information for the county and five municipalities is presented in Table B.3. As shown in the table, all of the incorporated town and cities have similar percentages of seasonal housing units compared to the unincorporated county. Jurisdiction TABLE B.3: HOUSING CHARACTERISTICS OF DESOTO COUNTY Housing Units (2000) Housing Units (2010) Seasonal Units, Percent (2010) Median Home Value ( ) DeSoto County 40,795 61, % $151,200 Hernando 2,720 5, % $170,500 Horn Lake 5,153 9, % $94,900 Olive Branch 7,935 12, % $163,100 Southaven 11,462 19, % $137,800 Walls % $120,800 Source: United States Census Bureau, 2000 and 2010 Census and American Community Survey 5-Year Estimates B.1.4 Infrastructure TRANSPORTATION In DeSoto County, Interstate 55 provides north-south access to areas in Memphis, Tennessee to north of New Orleans, Louisiana. DeSoto County contains Interstate 69 operating in the western area of the County. U.S. way 51 which is a north-south highway traveling from New Orleans, Louisiana north to B:3

4 the Wisconsin-Minnesota state border operates within DeSoto County. U.S. way 61, a north-south highway, travels through DeSoto County. DeSoto County contains six aircraft facilities. Olive Branch Public/Private Airport, in DeSoto County, is a privately owned but publicly used airport categorized as a general aviation reliever airport. Hernando Village Private/Public Airpark privately owned and publicly used has hanger space available to pilots and their aircraft. Finally, Eagles Ridge Private/Public will be open to the public soon. Vaiden Landing, Colonial, and Delta Flying Service Airports are all privately owned and for private use only airport facilities. The closest international airport is in Memphis, less than 15 miles away from the county. Multiple freight rail lines operate within DeSoto County. In northeastern DeSoto County the Burlington Northern Sante Fe Railway, a Class I Major railroad, operates. Grenada Railroad is a Class III Local railroad running through central DeSoto County. TN Terminal is another Class III Local railroad within DeSoto County. UTILITIES Electrical power in DeSoto County is provided by the Coahoma electric power association. Entergy Utility serves DeSoto County. Northcentral Mississippi electric power association and South Mississippi electric power association serve DeSoto County. DeSoto County is provided service from Tallahatchie Valley electric power association, as well. Water and sewer service is provided by all of the participating towns and/or community based associations, but unincorporated areas often rely on septic systems and wells in DeSoto County. Southaven Water Department and Utilities Division provide services to the City of Southaven. Olive Branch Public Utilities provides service to the City of Olive Branch. Belmont Waster Association in an additional service provider located in the City of Hernando. COMMUNITY FACILITIES There are a number of buildings and community facilities located throughout DeSoto County. According to the data collected for the vulnerability assessment (Section 6.4.1), there are 21 fire stations, 7 police stations, and 35 schools located within the county. There are two hospitals located in DeSoto County. Baptist Memorial Hospital-North Mississippi is a 242- bed general medical and surgical care facility serving northern Mississippi with an accredited rehabilitation facility. Methodist Olive Branch Hospital is a 100 bed hospital that opened in DeSoto County Museum located in the City of Hernando and contains exhibits related to civil war history and other history associated with the County. The City of Southaven, within DeSoto County, contains the Arena at Southaven which offers access to horse shows, rodeos, expos and trade shows. The City of Southaven also operated multiple different sports complex pertaining to football, baseball, softball, soccer and gold. The Snowden Grove Amphitheater in DeSoto County features summer music concerts and festivals. DeSoto County contains various water features that can be accessed for recreations in designated areas. These water features include Arkabutla Lake, Coldwater River, Mississippi Delta Bluffs, and the Mississippi River. Hernando DeSoto Park, within DeSoto County, features hiking and walking trails, B:4

5 river overlook, picnic area, boat parking and launch access to the Mississippi River. A variety of community parks throughout DeSoto County are operated and maintained by the County. B.1.5 Land Use Many areas of DeSoto County are undeveloped or sparsely developed. There are several small incorporated municipalities located throughout the county, with a few larger hubs interspersed. These areas are where the county s population is generally concentrated. The incorporated areas are also where many of the businesses, commercial uses, and institutional uses are located. Land uses in the balance of the county generally consist of rural residential development, agricultural uses, and recreational areas, although there are some notable exceptions in the larger municipalities. Local land use and associated regulations are further discussed in Section 7: Capability Assessment. North Delta Planning and Development District provides services related to regional planning, local technical assistance, and coordination and review of applications for federally sponsored programs within Northwest Mississippi. The purpose of the district is to promote economic development, encourage responsibility short and long term community planning, and to aid in general civic, social, and economic development. B.1.6 Employment and Industry According to the U.S. Census Bureau s American Community Survey (ACS), in 2014, DeSoto County had an average annual employment of 88,271 workers and an average unemployment rate of 5.7 percent (compared to 6.3 percent for the state). In 2014, the Education services, and health care and social assistance industry employed 20.5 percent of the county s workforce followed by Transportation and warehousing, and utilities (12.8%); Manufacturing (10.7%); Retail trade (10.5%); and Arts, entertainment, and recreation, and accommodation and food services (10.3%). The average annual median household in 2014 for DeSoto County was $58,995 compared to $39,464 in the state of Mississippi. B.2 DESOTO COUNTY RISK ASSESSMENT This subsection includes hazard profiles for each of the significant hazards identified in Section 4: Hazard Identification as they pertain to DeSoto County. Each hazard profile includes a description of the hazard s location and extent, notable historical occurrences, and the probability of future occurrences. Additional information can be found in Section 5: Hazard Profiles. FLOOD-RELATED HAZARDS B.2.1 Dam and Levee Failure LOCATION AND SPATIAL EXTENT According to the Mississippi Department of Environmental Quality, there are 26 high hazard dams in DeSoto County. 1 Figure B.2 shows the location of these high hazard dam and Table B.4 lists them by name. 1 The list of high hazard dams obtained from the Mississippi Department of Environmental Quality was reviewed and amended by local officials to the best of their knowledge. B:5

6 FIGURE B.2: DESOTO COUNTY HIGH HAZARD DAM LOCATIONS Source: Mississippi Department of Environmental Quality TABLE B.4: DESOTO COUNTY HIGH HAZARD DAMS Dam Name Hazard Potential DeSoto County APPLE CREEK DAM APPLE CREEK NORTH DAM ARKABUTLA DAM BLUE SPRINGS LAKE A DAM CENTRAL PARK LAKE DAM CROSS CREEK DAM - EAST LAKE DAM CROSS CREEK DAM - WEST LAKE DAM DEER TRACK LAKE DAM FOX LAKE DAM GRAYS CREEK LAKE #1 DAM HILDERBRANT LAKE DAM J E LYON POND DAM LAKE GREENBROOK DAM B:6

7 Dam Name LAKE O' THE HILLS DAM MASON LAKE DAM MAYWOOD SUBDIVISION - SHAHKOKA DAM MAYWOOD SUBDIVISION - WOODLAND LAKE DAM MCINVALE LAKE DAM MEGAN DRIVE LAKE DAM R N VAN VULPEN POND DAM RAIN CLOUD LAKE DAM SHORT FORK POND DAM STONEHEDGE DAM WANITA MANN POND DAM WILL BOND INCORPORATED POND DAM WOODLAND LAKE DAM Source: Mississippi Department of Environmental Quality Hazard Potential HISTORICAL OCCURRENCES According to the Mississippi State Hazard Mitigation Plan, there have been two dam failures reported in DeSoto County. Although no damage was reported with these events, several breach scenarios in the region could be catastrophic. Table B.5 below provides a brief description of the five reported dam failures. TABLE B.5: DESOTO COUNTY DAM FAILURES ( ) Date County Structure Name Cause of Failure April 1994 DeSoto Strickland Lake Breached by Regulators 2005 DeSoto Allen Subdivision Lake Source: Mississippi Department of Environmental Quality PROBABILITY OF FUTURE OCCURRENCES Animal penetration, causing dam to breach Given the current dam inventory and historic data, a dam breach is unlikely (less than 1 percent annual probability) in the future. As has been demonstrated in the past, regular monitoring is necessary to prevent these events. B.2.2 Erosion LOCATION AND SPATIAL EXTENT Erosion in DeSoto County is typically caused by flash flooding events. Unlike coastal areas, areas of concern for erosion in DeSoto County are primarily rivers/streams and reservoirs. Generally, vegetation helps to prevent erosion in the area, and it is not an extreme threat to the county. At this time, there is no data available on localized areas of erosion so it is not possible to depict extent on a map. B:7

8 HISTORICAL OCCURRENCES Several sources were vetted to identify areas of erosion in DeSoto County. This includes searching local newspapers, interviewing local officials, and reviewing previous hazard mitigation plans. No major historical erosion occurrences were found in these sources. PROBABILITY OF FUTURE OCCURRENCES Erosion remains a natural, dynamic, and continuous process for DeSoto County, and it will continue to occur. The annual probability level assigned for erosion is likely (between 10 and 100 percent annually). B.2.3 Flood LOCATION AND SPATIAL EXTENT There are areas in DeSoto County that are susceptible to flood events. Special flood hazard areas in the county were mapped using Geographic Information System (GIS) and FEMA Digital Flood Insurance Rate Maps (DFIRM). 2 This includes Zone A (1-percent annual chance floodplain) and Zone AE (1-percent annual chance floodplain with elevation). According to GIS analysis, of the square miles that make up DeSoto County, there are square miles of land in zones A and AE (1-percent annual chance floodplain/100-year floodplain). These flood zone values account for 24.5 percent of the total land area in DeSoto County. It is important to note that while FEMA digital flood data is recognized as best available data for planning purposes, it does not always reflect the most accurate and up-to-date flood risk. Flooding and flood-related losses often do occur outside of delineated special flood hazard areas. Figure B.3 illustrates the location and extent of currently mapped special flood hazard areas for DeSoto County based on best available FEMA Digital Flood Insurance Rate Map (DFIRM) data. 2 The county-level DFIRM data used for DeSoto County were updated in B:8

9 FIGURE B.3: SPECIAL FLOOD HAZARD AREAS IN DESOTO COUNTY Source: Federal Emergency Management Agency HISTORICAL OCCURRENCES Floods were at least partially responsible for four disaster declarations in DeSoto County in 1973, 2001, and twice in Information from the National Climatic Data Center was used to ascertain additional historical flood events. The National Climatic Data Center reported a total of 60 events in DeSoto County since A summary of these events is presented in Table B.6. These events accounted for almost $11.8 million (2016 dollars) in property damage and two fatalities in the county. 5 Specific information on flood events, including date, type of flooding, and deaths and injuries, can be found in Table B.7. 3 A complete listing of historical disaster declarations can be found in Section 4: Hazard Identification. 4 These flood events are only inclusive of those reported by the National Climatic Data Center (NCDC) from 1996 through March It is likely that additional occurrences have occurred and have gone unreported. As additional local data becomes available, this hazard profile will be amended. 5 Adjusted dollar values were calculated based on the average Consumer Price Index for a given calendar year. This index value has been calculated every year since For 2016, the May 2016 monthly index was used. B:9

10 Location TABLE B.6: SUMMARY OF FLOOD OCCURRENCES IN DESOTO COUNTY Number of Occurrences Deaths/Injuries Property Damage (2016) Annualized Property Losses Hernando 5 0/0 $26,675 $1,905 Horn Lake 7 0/0 $6,271,260 $447,947 Olive Branch 12 0/0 $61,281 $4,714 Southaven 6 0/0 $7,245 $381 Walls 1 0/0 $0 $0 Unincorporated Area 29 2/0 $5,390,792 $359,386 DESOTO COUNTY TOTAL Source: National Climatic Data Center 60 2/0 $11,757,253 $814,334 Hernando TABLE B.7: HISTORICAL FLOOD EVENTS IN DESOTO COUNTY Location Date Type Deaths/Injuries Property Damage* HERNANDO 8/16/2002 Flood 0/0 $1,335 HERNANDO 4/4/2008 Flash Flood 0/0 $0 HERNANDO 4/27/2014 Flash Flood 0/0 $0 HERNANDO 6/29/2014 Flash Flood 0/0 $0 HERNANDO 7/3/2015 Flash Flood 0/0 $25,340 Horn Lake HORN LAKE 9/19/2002 Flash Flood 0/0 $1,335 HORN LAKE 9/20/2002 Flash Flood 0/0 $1,335 HORN LAKE 12/19/2002 Flash Flood 0/0 $6,677 HORN LAKE 7/18/2003 Flash Flood 0/0 $1,306 HORN LAKE 7/15/2005 Flash Flood 0/0 $6,150,435 HORN LAKE 7/30/2009 Flash Flood 0/0 $0 HORN LAKE 5/1/2010 Flash Flood 0/0 $110,172 Olive Branch OLIVE BRANCH 5/17/2003 Flash Flood 0/0 $1,306 OLIVE BRANCH 3/20/2004 Flash Flood 0/0 $1,272 OLIVE BRANCH 6/18/2004 Flash Flood 0/0 $1,272 OLIVE BRANCH 7/19/2005 Flash Flood 0/0 $1,230 OLIVE BRANCH 1/10/2008 Flash Flood 0/0 $0 OLIVE BRANCH 4/1/2008 Flash Flood 0/0 $0 OLIVE BRANCH 7/9/2008 Flash Flood 0/0 $0 OLIVE BRANCH 8/25/2008 Flash Flood 0/0 $0 OLIVE BRANCH 10/7/2008 Flash Flood 0/0 $1,116 OLIVE BRANCH 7/16/2009 Flash Flood 0/0 $0 OLIVE BRANCH 4/24/2010 Flash Flood 0/0 $0 OLIVE BRANCH 5/1/2010 Flash Flood 0/0 $55,086 South Haven SOUTHAVEN 3/5/1997 Flash Flood 0/0 $2,994 SOUTH HAVEN 7/13/1998 Flood 0/0 $1,474 SOUTH HAVEN 4/3/1999 Flood 0/0 $1,442 B:10

11 Location Date Type Deaths/Injuries Property Damage* SOUTH HAVEN 7/12/2002 Flash Flood 0/0 $1,335 SOUTH HAVEN 5/2/2008 Flash Flood 0/0 $0 SOUTH HAVEN 7/16/2009 Flash Flood 0/0 $0 Walls WALLS 6/6/2014 Flash Flood 0/0 $0 Unincorporated Area DE SOTO (ZONE) 11/28/2001 Flood 1/0 $1,017,374 DE SOTO (ZONE) 12/12/2001 Flood 0/0 $1,357 DE SOTO (ZONE) 12/15/2001 Flood 0/0 $6,783 COUNTYWIDE 10/10/2002 Flash Flood 1/0 $6,677 DE SOTO (ZONE) 10/10/2002 Flood 0/0 $13,354 COUNTYWIDE 2/15/2004 Flash Flood 0/0 $1,272 HORN LAKE DESOTO ARP 3/31/2008 Flash Flood 0/0 $0 LYNCHBURG 4/11/2008 Flash Flood 0/0 $0 HORN LAKE DESOTO ARP 5/10/2008 Flash Flood 0/0 $0 INGRAMS MILL 7/22/2008 Flash Flood 0/0 $5,579 HANDY CORNER 7/31/2008 Flash Flood 0/0 $0 NESBIT 7/31/2008 Flash Flood 0/0 $0 COCKRUM 5/6/2009 Flash Flood 0/0 $55,989 NESBIT 12/8/2009 Flash Flood 0/0 $0 LYNCHBURG 4/26/2011 Flash Flood 0/0 $267,001 PENTON 5/1/2011 Flood 0/0 $801,004 MILLER 9/2/2012 Flash Flood 0/0 $0 BRIGHT 9/6/2012 Flash Flood 0/0 $10,464 LYNCHBURG 1/30/2013 Flash Flood 0/0 $103,125 HORN LAKE DESOTO ARP 5/21/2013 Flash Flood 0/0 $1,031,246 MINERAL WELLS 7/5/2013 Flash Flood 0/0 $0 FREES CORNER 2/4/2014 Flash Flood 0/0 $0 LYNCHBURG 6/8/2014 Flash Flood 0/0 $0 HORN LAKE DESOTO ARP 7/23/2014 Flash Flood 0/0 $0 STONEWALL 9/11/2014 Flash Flood 0/0 $2,029,569 LAKE CORMORANT 11/17/2015 Flash Flood 0/0 $0 LAKE CORMORANT 3/9/2016 Flash Flood 0/0 $0 NORFOLK 3/10/2016 Flood 0/0 $15,000 LOVE 3/10/2016 Flash Flood 0/0 $25,000 *Property damage is reported in 2016 dollars; all damage may not have been reported. Source: National Climatic Data Center HISTORICAL SUMMARY OF INSURED FLOOD LOSSES According to FEMA flood insurance policy records as of June 2016, there have been 216 flood losses reported in DeSoto County through the National Flood Insurance Program (NFIP) since 1978, totaling more than $5.4 million in claims payments. A summary of these figures for the county is provided in Table B.8. It should be emphasized that these numbers include only those losses to structures that were insured through the NFIP policies, and for losses in which claims were sought and received. It is likely that many additional instances of flood loss in DeSoto County were either uninsured, denied claims payment, or not reported. B:11

12 TABLE B.8: SUMMARY OF INSURED FLOOD LOSSES IN DESOTO COUNTY Location Number of Policies Flood Losses Claims Payments Hernando 27 4 $131,098 Horn Lake $1,542,756 Olive Branch $363,077 Southaven $2,250,137 Walls 10 0 $0 Unincorporated Area $1,138,498 DESOTO COUNTY TOTAL $5,425,566 Source: National Flood Insurance Program REPETITIVE LOSS PROPERTIES According to the Mississippi Emergency Management Agency, there are 9 non-mitigated repetitive loss properties located in DeSoto County, which accounted for 22 losses and over $670,000 in claims payments under the NFIP. The average claim amount for these properties is $30,466. Of the nine properties, seven are single family and two are non-residential. Without mitigation, these properties will likely continue to experience flood losses. Table B.9 presents detailed information on repetitive loss properties and NFIP claims and policies for DeSoto County. Location TABLE B.9: REPETITIVE LOSS PROPERTIES IN DESOTO COUNTY Number of Properties Hernando 1 Horn Lake 1 Olive Branch 4 Southaven 1 Types of Properties Number of Losses Building Payments Content Payments Total Payments Average Payment 1 single family 3 $156,702 $116,794 $273,496 $91,165 1 nonresidential 2 $0 $26,548 $26,548 $13,274 3 single family, 1 nonresidential 9 $144,888 $30,678 $175,566 $19,507 1 single family 4 $62,133 $17,579 $79,712 $19,928 Walls $0 $0 $0 $0 Unincorporated Area 2 DESOTO COUNTY TOTAL Source: National Flood Insurance Program 2 single family 4 $91,498 $23,442 $114,939 $28, $455,221 $215,040 $670,261 $30,466 PROBABILITY OF FUTURE OCCURRENCES Flood events will remain a threat in DeSoto County, and the probability of future occurrences will remain highly likely (100 percent annual probability). The participating jurisdictions and unincorporated areas have risk to flooding, though not all areas will experience flood. The probability of future flood events based on magnitude and according to best available data is illustrated in the figure above, which indicates B:12

13 those areas susceptible to the 1-percent annual chance flood (100-year floodplain). It can be inferred from the floodplain location maps, previous occurrences, and repetitive loss properties that risk varies throughout the county. For example, the southern half of the county has more floodplain and thus a higher risk of flood than the rest of the county. Flood is not the greatest hazard of concern but will continue to occur and cause damage. Therefore, mitigation actions may be warranted, particularly for repetitive loss properties. FIRE-RELATED HAZARDS B.2.4 Drought LOCATION AND SPATIAL EXTENT Drought typically covers a large area and cannot be confined to any geographic or political boundaries. Furthermore, it is assumed that DeSoto County would be uniformly exposed to drought, making the spatial extent potentially widespread. It is also notable that drought conditions typically do not cause significant damage to the built environment but may exacerbate wildfire conditions. HISTORICAL OCCURRENCES According to the U.S. Drought Monitor, DeSoto County had drought levels of Severe or worse in 9 of the last 17 years (January 2000-June 2016). Table B.10 shows the most severe drought classification for each year, according to U.S. Drought Monitor classifications. It should be noted that the U.S. Drought Monitor also estimates what percentage of the county is in each classification of drought severity. For example, the most severe classification reported may be exceptional but a majority of the county may actually be in a less severe condition. TABLE B.10: HISTORICAL DROUGHT OCCURRENCES IN DESOTO COUNTY Abnormally Dry (D0) Moderate Drought (D1) Severe Drought (D2) Extreme Drought (D3) Exceptional Drought (D4) Year DeSoto County 2000 EXCEPTIONAL 2001 SEVERE 2002 ABNORMAL 2003 ABNORMAL 2004 ABNORMAL 2005 SEVERE 2006 SEVERE 2007 EXTREME 2008 ABNORMAL 2009 None 2010 SEVERE 2011 SEVERE 2012 EXTREME B:13

14 Year DeSoto County 2013 MODERATE 2014 ABNORMAL 2015 SEVERE 2016 None Source: United States Drought Monitor (through June 2016) Some additional anecdotal information was provided from the National Climatic Data Center on droughts in DeSoto County. Summer 2007 Drought conditions began in early April across portions of Northeast Mississippi and expanded to North Central Mississippi by the end of April. Drought conditions continued throughout the summer months through October and at times reached exceptional conditions. The drought impacted agricultural and hydrological interests of the area. Burn bans in some locations were issued due to the lack of rainfall. Summer 2010 to Spring 2011 Below normal rainfall from June 2010 until April 2011 resulted in drought across Northwest Mississippi. The biggest impact of the drought was on agriculture as many crops suffered due to the lack of rainfall. Many pastures were in poor condition forcing farmers to feed livestock with baled hay. Hydrological concerns started to become an issue by the end of September into March as many lake and river levels dropped. Lack of moisture in the ground also caused several pipes to burst in the region. Burn bans were issued for most of North Mississippi. Summer 2012 Below normal rainfall fell during the month of July across North Mississippi. Many crops that were planted during the spring struggled to grow due to lack of water. Many pastures were in poor condition forcing farmers to feed cattle baled hay. Lake and river levels dropped to low levels. Burn bans were issued for many counties as a result of the dry conditions. Drought conditions improved during the month of October. PROBABILITY OF FUTURE OCCURRENCES Based on historical occurrence information, it is assumed that DeSoto County has a probability level of likely (between 10 and 100 percent annual probability) for future drought events. However, the extent (or magnitude) of drought and the amount of geographic area covered by drought, varies with each year. Historic information indicates that there is a much lower probability for extreme, long-lasting drought conditions. B.2.5 Lightning LOCATION AND SPATIAL EXTENT Lightning occurs randomly, therefore it is impossible to predict where and with what frequency it will strike. It is assumed that all of DeSoto County is uniformly exposed to lightning. B:14

15 HISTORICAL OCCURRENCES According to the National Climatic Data Center, there have been seven recorded lightning events in DeSoto County since These events resulted in over $792,000 (2016 dollars) in damages, as listed in summary Table B Furthermore, lightning caused seven injuries in DeSoto County. Detailed information on historical lightning events can be found in Table B.12. It is certain that more than seven events have impacted the county. Many of the reported events are those that cause damage, and it should be expected that damages are likely much higher for this hazard than what is reported. TABLE B.11: SUMMARY OF LIGHTNING OCCURRENCES IN DESOTO COUNTY Location Number of Occurrences Deaths/Injuries Property Damage (2016) Annualized Property Losses Hernando 1 0/0 $1,306 $100 Horn Lake 1 0/0 $31,794 $2,650 Olive Branch 1 0/0 $1,306 $100 Southaven 3 0/7 $747,604 $49,840 Walls 1 0/0 $10,464 $2,616 Unincorporated Area 0 0/0 $0 $0 DESOTO COUNTY TOTAL Source: National Climatic Data Center 7 0/7 $792,474 $55,307 Location Hernando TABLE B.12: HISTORICAL LIGHTNING OCCURRENCES IN DESOTO COUNTY Date Deaths/ Injuries Property Damage* Details HERNANDO 5/5/2003 0/0 $1,306 A large tree was hit by lightning and fell down. Horn Lake HORN LAKE 8/23/2004 0/0 $31,794 Olive Branch A house was badly damaged by a fire started by lightning. OLIVE BRANCH 7/13/2003 0/0 $1,306 A house was damaged by a fire set by lightning. Southaven SOUTH HAVEN 7/29/2001 0/6 $0 SOUTH HAVEN 5/1/2003 0/1 $0 SOUTH HAVEN 6/16/2011 0/0 $747,604 Six persons were injured when lightning struck a baseball dugout during a baseball tournament. A lady was injured by a lightning strike while walking to her car. Lightning struck an apartment complex in Southaven starting a fire that destroyed 8 units. A section of the roof collapsed into the structure as well. 6 These lightning events are only inclusive of those reported by the National Climatic Data Center (NCDC) from 1996 through March It is certain that additional lightning events have occurred in DeSoto County. As additional local data becomes available, this hazard profile will be amended. 7 Adjusted dollar values were calculated based on the average Consumer Price Index for a given calendar year. This index value has been calculated every year since For 2016, the May 2016 monthly index was used. B:15

16 Location Walls Date Deaths/ Injuries Property Damage* Details WALLS 9/6/2012 0/0 $10,464 A lightning strike resulted in a structure fire in Walls. Unincorporated area None Reported *Property damage is reported in 2016 dollars; all damage may not have been reported. Source: National Climatic Data Center PROBABILITY OF FUTURE OCCURRENCES Although there was not a high number of historical lightning events reported in DeSoto County via NCDC data, it is a regular occurrence accompanied by thunderstorms. In fact, lightning events will assuredly happen on an annual basis, though not all events will cause damage. According to Vaisala s U.S. National Lightning Detection Network (NLDN), DeSoto County is located in an area of the country that experienced an average of 4 to 12 lightning flashes per square kilometer per year between 2005 and Therefore, the probability of future events is highly likely (100 percent annual probability). It can be expected that future lightning events will continue to threaten life and cause minor property damages throughout the county. B.2.6 Wildfire LOCATION AND SPATIAL EXTENT The entire county is at risk to a wildfire occurrence. However, several factors such as drought conditions or high levels of fuel on the forest floor, may make a wildfire more likely. Furthermore, areas in the urbanwildland interface are particularly susceptible to fire hazard as populations abut formerly undeveloped areas. The Wildfire Ignition Density data shown in the figure below give an indication of historic location. HISTORICAL OCCURRENCES Figure B.4 shows the Wildfire Ignition Density in DeSoto County based on data from the Southern Wildfire Risk Assessment. This data is based on historical fire ignitions and the likelihood of a wildfire igniting in an area. Occurrence is derived by modeling historic wildfire ignition locations to create an average ignition rate map. This is measured in the number of fires per year per 1,000 acres. 8 8 Southern Wildfire Risk Assessment, B:16

17 FIGURE B.4: WILDFIRE IGNITION DENSITY IN DESOTO COUNTY Source: Southern Wildfire Risk Assessment Based on data from the Mississippi Forestry Commission from 2012 to 2016, DeSoto County experienced an average of 1.0 wildfires annually which burned a combined 15.0 acres per year. The data indicate that these fires averaged about 15.0 acres per fire. Table B.13 provides a summary of wildfire occurrences in DeSoto County and Table B.14 lists the number of reported wildfire occurrences in the county between the years 2012 and TABLE B.13: SUMMARY TABLE OF ANNUAL WILDFIRE OCCURRENCES ( )* DeSoto County Average Number of Fires per year 1.0 Average Number of Acres Burned per year 15.0 Average Number of Acres Burned per fire 15.0 *These values reflect averages over a 5-year period. Source: Mississippi Forestry Commission B:17

18 TABLE B.14: HISTORICAL WILDFIRE OCCURRENCES IN DESOTO COUNTY Year DeSoto County Number of Fires Number of Acres Burned Source: Mississippi Forestry Commission PROBABILITY OF FUTURE OCCURRENCES Wildfire events will be an ongoing occurrence in DeSoto County. Figure B.5 shows that there is some probability a wildfire will occur throughout the county. However, the likelihood of wildfires increases during drought cycles and abnormally dry conditions. Fires are likely to stay small in size but could increase due to local climate and ground conditions. Dry, windy conditions with an accumulation of forest floor fuel (potentially due to ice storms or lack of fire) could create conditions for a large fire that spreads quickly. It should also be noted that some areas do vary somewhat in risk. For example, highly developed areas are less susceptible unless they are located near the urban-wildland boundary. The risk will also vary due to assets. Areas in the urban-wildland interface will have much more property at risk, resulting in increased vulnerability and need to mitigate compared to rural, mainly forested areas. The probability assigned to DeSoto County for future wildfire events is highly likely (100 percent annual probability). B:18

19 FIGURE B.5: BURN PROBABILITY IN DESOTO COUNTY Source: Southern Wildfire Risk Assessment GEOLOGIC HAZARDS B.2.7 Earthquake LOCATION AND SPATIAL EXTENT Figure B.6 shows the intensity level associated with DeSoto County, based on the national USGS map of peak acceleration with 10 percent probability of exceedance in 50 years. It is the probability that ground motion will reach a certain level during an earthquake. The data show peak horizontal ground acceleration (the fastest measured change in speed, for a particle at ground level that is moving horizontally due to an earthquake) with a 10 percent probability of exceedance in 50 years. The map was compiled by the U.S. Geological Survey (USGS) Geologic Hazards Team, which conducts global investigations of earthquake, geomagnetic, and landslide hazards. According to this map, DeSoto County lies within an approximate zone of level 0.1 to 0.2 ground acceleration. This indicates that the county exists within an area of high seismic risk. B:19

20 FIGURE B.6: PEAK ACCELERATION WITH 10 PERCENT PROBABILITY OF EXCEEDANCE IN 50 YEARS Source: United States Geological Survey, 2014 B:20

21 It should also be noted that the State of Mississippi Hazard Mitigation Plan identifies certain areas of concern for liquefaction and lists the counties and corresponding zones within those counties that have the highest liquefaction potential. The zones of high risk for DeSoto County can be found in Table B.15. County DeSoto County TABLE B.15: HIGH LIQUEFACTION HAZARD FOR DESOTO COUNTY Seismic Source* NMSZ, WRFZ *NMSZ = New Madrid Seismic Zone; WRFZ = White River Fault Zone Source: State of Mississippi Standard Mitigation Plan (2013 Update) Geographic Area of Concern Mississippi River Floodplain, Coldwater River Floodplain Liquefaction Potential by Seismic Zone Very, Very Low HISTORICAL OCCURRENCES At least 22 earthquakes are known to have affected DeSoto County since The strongest of these measured a V on the Modified Mercalli Intensity (MMI) scale. Table B.16 provides a summary of earthquake events reported by the National Geophysical Data Center between 1638 and Table B.17 presents a detailed occurrence of each event including the date, distance for the epicenter, magnitude and Modified Mercalli Intensity (if known). 9 TABLE B.16: SUMMARY OF SEISMIC ACTIVITY IN DESOTO COUNTY Location Number of Occurrences Greatest MMI Reported Greatest Richter Scale Reported Hernando 7 V 5.3 Horn Lake 3 IV 4.9 Olive Branch 2 V 4.9 Southaven Walls 3 V 4.9 Unincorporated Area 7 V 4.9 DESOTO COUNTY TOTAL 22 V (slightly strong) 5.3 Source: National Geophysical Data Center TABLE B.17: SIGNIFICANT SEISMIC EVENTS IN DESOTO COUNTY ( ) Location Date Epicentral Distance Magnitude MMI Hernando Hernando 12/17/ km Unknown V Hernando 12/16/1947 Unknown Unknown III Hernando 1/25/ km Unknown III Hernando 6/4/ km 3.8 IV Hernando 11/9/ km 5.3 IV Hernando 11/17/ km 3.6 IV Hernando 3/25/ km 4.9 V 9 Due to reporting mechanisms, not all earthquakes events were recorded during this time. Furthermore, some are missing data, such as the epicenter location, due to a lack of widely used technology. In these instances, a value of unknown is reported. B:21

22 Location Date Epicentral Distance Magnitude MMI Horn Lake Horn Lake 3/3/ km 4.5 III Horn Lake 3/29/ km 3.7 III Horn Lake 3/25/ km 4.9 IV Olive Branch Olive Branch 11/17/ km 3.6 III Olive Branch 3/25/ km 4.9 V Southaven None Reported Walls Walls 3/3/ km 4.5 III Walls 11/17/ km 3.6 IV Walls 3/25/ km 4.9 V Unincorporated Area Lake Cormorant 12/17/ km Unknown IV Lake Cormorant 3/3/ km 4.5 III Lake Cormorant 6/4/ km 3.8 IV Mineral Wells 3/29/ km 3.7 IV Lake Cormorant 3/25/ km 4.9 V Mineral Wells 3/25/ km 4.9 V Nesbit 3/25/ km 4.9 V Source: National Geophysical Data Center PROBABILITY OF FUTURE OCCURRENCES The probability of significant, damaging earthquake events affecting DeSoto County is unlikely. However, it is certainly possible that future earthquakes resulting in light or moderate perceived shaking and damages will affect the county much more frequently. The annual probability level for the county is estimated to be between 10 and 100 percent (likely). B.2.8 Landslide LOCATION AND SPATIAL EXTENT Landslides occur along steep slopes when the pull of gravity can no longer be resisted (often due to heavy rain). Human development can also exacerbate risk by building on previously undevelopable steep slopes. Landslides are possible throughout DeSoto County, though the risk is relatively low. According to Figure B.7 below, approximately half of the county falls under a low incidence area, indicating that in these zones less than 1.5 percent of the area is involved in landsliding. The other half has moderate incidence, indicating that between 1.5 and 15 percent of the area is involved in landsliding. There are also areas in the northwestern corner and center of the county that have high susceptibility, indicating that there is a somewhat higher potential for landslides to occur in these area. B:22

23 FIGURE B.7: LANDSLIDE SUSCEPTIBILITY AND INCIDENCE MAP OF DESOTO COUNTY Source: United States Geological Survey HISTORICAL OCCURRENCES There is no extensive history of landslides in DeSoto County. Landslide events typically occur in isolated areas, but no major landslide events were reported. PROBABILITY OF FUTURE OCCURRENCES Based on historical information and the USGS susceptibility index, the probability of future landslide events is possible (between 1 and 10 percent annual probability). The USGS data indicates that half of the areas in DeSoto County have a low incidence rate and some areas also have low susceptibly to landsliding activity. There are areas in the northwestern corner and center of the county that have high susceptibility. Local conditions may become more favorable for landslides due to heavy rain, for example. This would increase the likelihood of occurrence. It should also be noted that some areas in DeSoto County have greater risk than others given factors such as steepness on slope and modification of slopes. B:23

24 B.2.9 Land Subsidence/Sinkhole LOCATION AND SPATIAL EXTENT According to the U.S. Geological Survey (USGS), subsidence affects an estimated 17,000 square miles in 45 states, including Mississippi. Salt and gypsum underlie about 35 to 40 percent of the United States, though in many areas they are buried at great depths. Figure B.8 shows the location of rock types associated with subsidence in the United States. It indicates that there may be areas in DeSoto County underlain with soil and rock types that are susceptible to land subsidence, but overall the northwest part of the state is not underlain by these soil/rock types. FIGURE B.8: MAP OF ROCK TYPES ASSOCIATED WITH SUBSIDENCE IN THE UNITED STATES Source: United States Geological Survey HISTORICAL OCCURRENCES Although there is no extensive recorded history of land subsidence in DeSoto County, anecdotal evidence of isolated incidents have been reported. Local county officials have noted the impacts from these swings and changes in soil as roads and other infrastructure have experienced large cracks and breaks, causing stops in daily operations and significant costs to local, state, and federal budgets. Often the cost to repair this infrastructure can be in the range of millions of dollars depending on the degree of damage and necessity for quick repairs. PROBABILITY OF FUTURE OCCURRENCES The probability of future land subsidence events in the county is possible (between 1 and 10 percent annual probability). The potential for land subsidence may be impacted by local conditions such as heavy rain or extremely dry periods. B:24

25 WIND-RELATED HAZARDS B.2.10 Extreme Heat LOCATION AND SPATIAL EXTENT Heat waves typically impact a large area and cannot be confined to any geographic or political boundaries. Therefore the entire county is considered to be equally susceptible to extreme heat. HISTORICAL OCCURRENCES The National Climatic Data Center was used to determine historical heat wave occurrences in the county. August 2007 During the first half of August, a heat wave took hold of the region and brought some of the warmest temperatures since the summer of This heat wave began around August 5th and lasted until the 16th. Between August 10th and 15th, the entire area reached 100 degrees or higher. Twenty three record highs were also set during this time. As the temperature soared each day, high relative humidities resulted in heat index values between 105 and 112 degrees. July to August 2010 pressure was firmly entrenched across the southeast and allowed temperatures to soar into the triple digits across much of the region numerous times during the months of July and August. Additionally, relatively high humidity levels made conditions even more oppressive, with heat index readings surpassing 110 degrees in many areas. July to August 2011 A strong upper ridge of high pressure moved over the Mid-South during the middle part of July and beginning of August. As a result, high temperatures ranged in the mid-90s to low 100s. Dew points ranged from the lower to upper 70s. The combination of the hot and humid conditions allowed heat indices to reach between 110 and 120 degrees during the afternoon hours. July 2012 An upper ridge of high pressure moved back over the Mid-South during the middle part of July. Temperatures rose into low 100s during the afternoon hours of July 19th-July 20th, The combination of heat and humidity produced heat indices above 110 degrees. PROBABILITY OF FUTURE OCCURRENCES Based on historical occurrence information, it is assumed that all of DeSoto County has a probability level of likely (between 10 and 100 percent annual probability) for future heat wave events. B.2.11 Hailstorm LOCATION AND SPATIAL EXTENT Hailstorms frequently accompany thunderstorms, so their locations and spatial extents coincide. It is assumed that DeSoto County is uniformly exposed to severe thunderstorms; therefore, all areas of the county are equally exposed to hail which may be produced by such storms. With that in mind, Figure B.9 shows the location of hail events that have impacted the county between 1955 and B:25

26 FIGURE B.9: HAILSTORM TRACKS IN DESOTO COUNTY Source: National Weather Service Storm Prediction Center HISTORICAL OCCURRENCES According to the National Climatic Data Center, 129 recorded hailstorm events have affected DeSoto County since Table B.18 is a summary of the hail events in DeSoto County. Table B.19 provides detailed information about each event that occurred in the county. In all, hail occurrences resulted in approximately $154,000 (2016 dollars) in property damages. 11 Hail ranged in diameter from 0.75 inches to 2.0 inches. It should be noted that hail is notorious for causing substantial damage to cars, roofs, and other areas of the built environment that may not be reported to the National Climatic Data Center. Therefore, it is likely that damages are greater than the reported value. 10 These hail events are only inclusive of those reported by the National Climatic Data Center (NCDC) from 1955 through March It is likely that additional hail events have affected DeSoto County. As additional local data becomes available, this hazard profile will be amended. 11 Adjusted dollar values were calculated based on the average Consumer Price Index for a given calendar year. This index value has been calculated every year since For 2016, the May 2016 monthly index was used. B:26

27 Location TABLE B.18: SUMMARY OF HAIL OCCURRENCES IN DESOTO COUNTY Number of Occurrences Deaths/Injuries Property Damage (2016) Annualized Property Losses Hernando 29 0/0 $28,945 $1,316 Horn Lake 9 0/0 $46,706 $2,123 Olive Branch 18 0/0 $20,842 $1,303 Southaven 14 0/0 $17,267 $785 Walls 6 0/0 $2,210 $130 Unincorporated Area 53 0/0 $37,796 $700 DESOTO COUNTY TOTAL Source: National Climatic Data Center 129 0/0 $153,766 $6,356 TABLE B.19: HISTORICAL HAIL OCCURRENCES IN DESOTO COUNTY Location Date Magnitude Deaths/Injuries Property Damage* Hernando Hernando 4/26/ in. 0/0 $811 Hernando 4/26/ in. 0/0 $81 Hernando 3/20/ in. 0/0 $158 Hernando 5/15/ in. 0/0 $7,882 Hernando 7/9/ in. 0/0 $158 HERNANDO 1/4/ in. 0/0 $15 HERNANDO 4/27/ in. 0/0 $15 HERNANDO 3/31/ in. 0/0 $136 HERNANDO 3/31/ in. 0/0 $14 HERNANDO 5/20/ in. 0/0 $1,017 HERNANDO 5/27/ in. 0/0 $14 HERNANDO 10/24/ in. 0/0 $14 HERNANDO 10/24/ in. 0/0 $14 HERNANDO 11/24/ in. 0/0 $136 HERNANDO 11/15/ in. 0/0 $1,304 HERNANDO 4/2/ in. 0/0 $4,171 HERNANDO 5/3/ in. 0/0 $1,192 HERNANDO 4/3/ in. 0/0 $2,317 HERNANDO 4/13/ in. 0/0 $2,317 HERNANDO 3/15/ in. 0/0 $2,232 HERNANDO 3/15/ in. 0/0 $1,116 HERNANDO 3/15/ in. 0/0 $1,116 HERNANDO 4/22/ in. 0/0 $1,674 HERNANDO 4/24/ in. 0/0 $0 HERNANDO 4/24/ in. 0/0 $0 HERNANDO 5/25/ in. 0/0 $0 HERNANDO 1/22/ in. 0/0 $1,046 HERNANDO 4/27/ in. 0/0 $0 HERNANDO 3/31/ in. 0/0 $0 B:27

28 Location Date Magnitude Deaths/Injuries Property Damage* Horn Lake Horn Lake 4/26/ in. 0/0 $811 HORN LAKE 4/24/ in. 0/0 $67 HORN LAKE 7/18/ in. 0/0 $131 HORN LAKE 4/7/ in. 0/0 $23,833 HORN LAKE 4/7/ in. 0/0 $17,875 HORN LAKE 4/3/ in. 0/0 $1,159 HORN LAKE 4/13/ in. 0/0 $1,159 HORN LAKE 5/22/ in. 0/0 $1,674 HORN LAKE 6/16/ in. 0/0 $0 Olive Branch OLIVE BRANCH 2/13/ in. 0/0 $1,395 OLIVE BRANCH 2/13/ in. 0/0 $14 OLIVE BRANCH 4/30/ in. 0/0 $13 OLIVE BRANCH 5/6/ in. 0/0 $6,528 OLIVE BRANCH 7/13/ in. 0/0 $78 OLIVE BRANCH 3/20/ in. 0/0 $127 OLIVE BRANCH 3/20/ in. 0/0 $153 OLIVE BRANCH 7/14/ in. 0/0 $1,081 OLIVE BRANCH 6/10/ in. 0/0 $123 OLIVE BRANCH 4/3/ in. 0/0 $2,317 OLIVE BRANCH 8/2/ in. 0/0 $2,317 OLIVE BRANCH 3/14/ in. 0/0 $5,579 OLIVE BRANCH 3/14/ in. 0/0 $1,116 OLIVE BRANCH 6/12/ in. 0/0 $0 OLIVE BRANCH 6/12/ in. 0/0 $0 OLIVE BRANCH 4/19/ in. 0/0 $0 OLIVE BRANCH 6/16/ in. 0/0 $0 OLIVE BRANCH 6/22/ in. 0/0 $0 Southaven Southaven 3/24/ in. 0/0 $0 Southaven 4/26/ in. 0/0 $811 Southaven 3/20/ in. 0/0 $315 Southaven 3/20/ in. 0/0 $158 SOUTH HAVEN 2/18/ in. 0/0 $14 SOUTH HAVEN 4/7/ in. 0/0 $14 SOUTH HAVEN 5/20/ in. 0/0 $1,017 SOUTH HAVEN 12/18/ in. 0/0 $13 SOUTH HAVEN 7/7/ in. 0/0 $967 SOUTH HAVEN 4/22/ in. 0/0 $12 SOUTH HAVEN 11/6/ in. 0/0 $135 SOUTH HAVEN 3/15/ in. 0/0 $1,116 SOUTH HAVEN 5/2/ in. 0/0 $2,232 SOUTH HAVEN 1/22/ in. 0/0 $10,464 Walls WALLS 5/4/ in. 0/0 $1,081 B:28

29 Location Date Magnitude Deaths/Injuries Property Damage* WALLS 11/6/ in. 0/0 $12 WALLS TWINKLE TOWN F 5/10/ in. 0/0 $1,116 WALLS 4/24/ in. 0/0 $0 WALLS 4/25/ in. 0/0 $0 WALLS 6/13/ in. 0/0 $0 Unincorporated Area DE SOTO CO. 3/31/ in. 0/0 $0 DE SOTO CO. 2/18/ in. 0/0 $0 DE SOTO CO. 4/30/ in. 0/0 $0 DE SOTO CO. 4/30/ in. 0/0 $0 DE SOTO CO. 4/30/ in. 0/0 $0 DE SOTO CO. 4/30/ in. 0/0 $0 DE SOTO CO. 7/31/ in. 0/0 $0 DE SOTO CO. 4/11/ in. 0/0 $0 DE SOTO CO. 8/14/ in. 0/0 $0 DE SOTO CO. 3/30/ in. 0/0 $0 DE SOTO CO. 6/3/ in. 0/0 $0 DE SOTO CO. 6/11/ in. 0/0 $0 Midway 8/2/ in. 0/0 $0 Byhalia 4/26/ in. 0/0 $811 Nesbit 4/26/ in. 0/0 $811 Penton 5/18/ in. 0/0 $1,576 NESBIT 4/27/ in. 0/0 $15 LEWISBURG 4/27/ in. 0/0 $15 LEWISBURG 5/28/ in. 0/0 $1,105 LEWISBURG 5/20/ in. 0/0 $136 LAKE CORMORANT 10/24/ in. 0/0 $14 PLEASANT HILL 11/24/ in. 0/0 $68 LEWISBURG 5/5/ in. 0/0 $13 LAKE CORMORANT 5/5/ in. 0/0 $326 EUDORA 7/18/ in. 0/0 $196 LEWISBURG 12/3/ in. 0/0 $62 EUDORA 1/13/ in. 0/0 $119 EUDORA 4/2/ in. 0/0 $7,150 EUDORA 5/10/ in. 0/0 $2,979 LEWISBURG 4/13/ in. 0/0 $1,159 DAYS 4/13/ in. 0/0 $1,159 FREES CORNER 3/15/ in. 0/0 $5,579 EUDORA 3/15/ in. 0/0 $1,116 NESBIT 3/15/ in. 0/0 $2,232 LEWISBURG 3/15/ in. 0/0 $1,116 BRIGHT 5/2/ in. 0/0 $1,674 HANDY CORNER 5/10/ in. 0/0 $1,674 LOVE 7/5/ in. 0/0 $1,116 BRIGHT 7/5/ in. 0/0 $5,579 CEDARVIEW 6/12/ in. 0/0 $0 B:29

30 Location Date Magnitude Deaths/Injuries Property Damage* EUDORA 4/24/ in. 0/0 $0 LAKE CORMORANT 4/24/ in. 0/0 $0 HORN LAKE DESOTO ARP 4/24/ in. 0/0 $0 PLEASANT HILL 4/24/ in. 0/0 $0 LOVE 4/19/ in. 0/0 $0 LOVE 4/26/ in. 0/0 $0 LEWISBURG 5/13/ in. 0/0 $0 MILLER 6/16/ in. 0/0 $0 MILLER 2/1/ in. 0/0 $0 HORN LAKE DESOTO ARP 7/7/ in. 0/0 $0 LEWISBURG 10/17/ in. 0/0 $0 MINERAL WELLS 6/27/ in. 0/0 $0 PLUM PT 10/2/ in. 0/0 $0 *Property damage is reported in 2016 dollars; all damage may not have been reported. Source: National Climatic Data Center PROBABILITY OF FUTURE OCCURRENCES Based on historical occurrence information, it is assumed that the probability of future hail occurrences is highly likely (100 percent annual probability). Since hail is an atmospheric hazard, it is assumed that DeSoto County has equal exposure to this hazard. It can be expected that future hail events will continue to cause minor damage to property and vehicles throughout the county. B.2.12 Hurricane and Tropical Storm LOCATION AND SPATIAL EXTENT Hurricanes and tropical storms threaten the entire Atlantic and Gulf seaboard of the United States. While coastal areas are most directly exposed to the brunt of landfalling storms, their impact is often felt hundreds of miles inland and they can affect DeSoto County. All areas in DeSoto County are equally susceptible to hurricane and tropical storms. HISTORICAL OCCURRENCES According to the National Hurricane Center s historical storm track records, 36 hurricane or tropical storm/depression tracks have passed within 75 miles of the MEMA District 1 Region since This includes: 1 Category 1 hurricane, 17 tropical storms, and 18 tropical depressions. A total of 20 tracks passed directly through the region as shown in Figure B.10. These events were all tropical storm or tropical depression strength at the time they traversed the region. Table B.20 provides the date of occurrence, name (if applicable), maximum wind speed (as recorded within 75 miles of the MEMA District 1 Region) and category of the storm based on the Saffir-Simpson Scale for each event. 12 These storm track statistics include tropical depressions, tropical storms, and hurricanes. Lesser events may still cause significant local impact in terms of rainfall and high winds. B:30

31 FIGURE B.10: HISTORICAL HURRICANE STORM TRACKS WITHIN 75 MILES OF THE MEMA DISTRICT 1 REGION Source: National Oceanic and Atmospheric Administration; National Hurricane Center TABLE B.20: HISTORICAL STORM TRACKS WITHIN 75 MILES OF THE MEMA 1 DISTRICT REGION ( ) Date of Occurrence Storm Name Maximum Wind Speed (knots) Storm Category 10/3/1860 UNNAMED 50 Tropical Storm 9/17/1862 NOT NAMED -- Tropical Depression 10/7/1879 NOT NAMED -- Tropical Depression 8/29/1881 UNNAMED 40 Tropical Storm 8/20/1888 UNNAMED 60 Tropical Storm 8/28/1890 UNNAMED 35 Tropical Storm 7/7/1891 UNNAMED 35 Tropical Storm 9/21/1898 UNNAMED 30 Tropical Depression 8/16/1901 UNNAMED 35 Tropical Storm 9/28/1906 UNNAMED 50 Tropical Storm 8/3/1908 UNNAMED 25 Tropical Depression B:31

32 Date of Occurrence Storm Name Maximum Wind Speed (knots) Storm Category 9/21/1909 UNNAMED 55 Tropical Storm 7/7/1916 UNNAMED 40 Tropical Storm 10/16/1923 UNNAMED 45 Tropical Storm 10/18/1923 UNNAMED 40 Tropical Storm 7/30/1926 UNNAMED 25 Tropical Depression 9/2/1932 UNNAMED 40 Tropical Storm 9/20/1932 UNNAMED 40 Tropical Storm 7/27/1933 UNNAMED 30 Tropical Depression 6/17/1934 UNNAMED 45 Tropical Storm 9/1/1937 UNNAMED 25 Tropical Depression 6/17/1939 UNNAMED 25 Tropical Depression 9/5/1948 UNNAMED 30 Tropical Depression 9/5/1949 UNNAMED 30 Tropical Depression 9/9/1950 EASY 20 Tropical Depression 6/28/1957 AUDREY 40 Tropical Storm 9/11/1965 BETSY 30 Tropical Depression 8/18/1969 CAMILLE 75 Category 1 7/12/1979 BOB 30 Tropical Depression 8/16/1985 DANNY 30 Tropical Depression 8/4/1995 ERIN 20 Tropical Depression 8/7/2001 BARRY 15 Tropical Depression 10/4/2002 LILI 30 Tropical Depression 7/11/2005 DENNIS 25 Tropical Depression 8/29/2005 KATRINA 50 Tropical Storm 8/30/2012 ISAAC 35 Tropical Storm Source: National Hurricane Center Federal records indicate that one disaster declaration was made in 2005 (Hurricane Katrina) in DeSoto County. 13 Hurricane and tropical storm events can cause substantial damage in the area due to high winds and flooding. The National Climatic Data Center also reported one hurricane or tropical storm event in DeSoto County since This storm is listed in Table B.21 and is generally representative of storms with the greatest impact on the county over that time period. TABLE B.21: HISTORICAL HURRICANE/TROPICAL STORM OCCURRENCES IN DESOTO COUNTY Date of Occurrence Storm Name Deaths/Injuries Property Damage (2016) 15 Annualized Property Losses 8/30/2005 Hurricane Katrina 0/0 $12,301 $1,118 Source: National Climatic Data Center 13 A complete listing of historical disaster declarations can be found in Section 4: Hazard Identification. 14 These hurricane events are only inclusive of those reported by the National Climatic Data Center (NCDC) from 1996 through March It is likely that additional occurrences have occurred and have gone unreported. 15 Adjusted dollar values were calculated based on the average Consumer Price Index for a given calendar year. This index value has been calculated every year since For 2016, the May 2016 monthly index was used. B:32

33 Flooding and high winds from hurricanes and tropical storms can cause damage throughout the county. Anecdotes are available from NCDC for the major storms that have impacted the county as found below: Hurricane Katrina August 29, 2005 Hurricane Katrina had weakened to tropical storm strength when it reached north Mississippi. Numerous trees and power lines along with some telephone poles were blown down. Some trees fell on cars, mobile homes and apartment buildings. Four to eight inches of rain fell in some parts of northeast Mississippi producing some flash flooding. Overall at least 100,000 customers lost power. PROBABILITY OF FUTURE OCCURRENCES Given the inland location of the county, it is more likely to be affected by remnants of hurricane and tropical storm systems (as opposed to a major hurricane) which may result in flooding or high winds. The probability of being impacted is less than coastal areas, but still remains a real threat to DeSoto County due to induced events like flooding. Based on historical evidence, the probability level of future occurrence is possible (between 1 and 10 percent annual probability). Given the regional nature of the hazard, all areas in the county are equally exposed to this hazard. However, when the county is impacted, the damage could be catastrophic, threatening lives and property throughout the planning area. B.2.13 Severe Thunderstorm/ Wind LOCATION AND SPATIAL EXTENT A thunderstorm event is an atmospheric hazard, and thus has no geographic boundaries. It is typically a widespread event that can occur in all regions of the United States. However, thunderstorms are most common in the central and southern states because atmospheric conditions in those regions are favorable for generating these powerful storms. It is assumed that DeSoto County has uniform exposure to an event and the spatial extent of an impact could be large. With that in mind, Figure B.11 shows the location of wind events that have impacted the county between 1955 and B:33

34 FIGURE B.11: SEVERE THUNDERSTORM TRACKS IN DESOTO COUNTY Source: National Weather Service Storm Prediction Center HISTORICAL OCCURRENCES Severe storms were at least partially responsible for two disaster declarations in Desoto County in 2001 and According to NCDC, there have been 142 reported thunderstorm and high wind events since 1961 in DeSoto County. 17 These events caused more than $10.4 million (2016 dollars) in damages. 18 There were also reports of one fatality and one injury. Table B.22 summarizes this information. Table B.23 presents detailed thunderstorm and high wind event reports including date, magnitude, and associated damages for each event. 16 A complete listing of historical disaster declarations can be found in Section 4: Hazard Identification. 17 These thunderstorm events are only inclusive of those reported by the National Climatic Data Center (NCDC) from 1955 through March 2016 and these high wind events are only inclusive of those reported by NCDC from 1996 through March It is likely that additional thunderstorm and high wind events have occurred in DeSoto County. As additional local data becomes available, this hazard profile will be amended. 18 Adjusted dollar values were calculated based on the average Consumer Price Index for a given calendar year. This index value has been calculated every year since For 2016, the May 2016 monthly index was used. B:34

35 TABLE B.22: SUMMARY OF THUNDERSTORM/HIGH WIND OCCURRENCES IN DESOTO COUNTY Location Number of Occurrences Deaths/Injuries Property Damage (2016) Annualized Property Losses Hernando 13 0/0 $91,634 $4,582 Horn Lake 9 0/0 $104,277 $4,534 Olive Branch 22 0/1 $3,512,459 $159,657 Southaven 11 0/0 $95,014 $4,751 Walls 9 0/0 $45,477 $2,274 Unincorporated Area 78 1/0 $6,588,686 $119,794 DESOTO COUNTY TOTAL Source: National Climatic Data Center 142 1/1 $10,437,547 $295,592 TABLE B.23: HISTORICAL THUNDERSTORM/HIGH WIND OCCURRENCES IN DESOTO COUNTY Location Date Type Magnitude Deaths/Injuries Hernando Property Damage* HERNANDO 11/7/1996 Thunderstorm Wind -- 0/0 $7,656 HERNANDO 7/20/2000 Thunderstorm Wind -- 0/0 $6,975 HERNANDO 3/31/2001 Thunderstorm Wind -- 0/0 $6,783 HERNANDO 5/20/2001 Thunderstorm Wind -- 0/0 $13,565 HERNANDO 5/20/2001 Thunderstorm Wind -- 0/0 $6,783 HERNANDO 8/13/2002 Thunderstorm Wind -- 0/0 $13,354 HERNANDO 5/30/2004 Thunderstorm Wind 55 kts. EG 0/0 $1,272 HERNANDO 9/25/2005 Thunderstorm Wind 50 kts. EG 0/0 $6,150 HERNANDO 10/17/2007 Thunderstorm Wind 50 kts. EG 0/0 $2,317 HERNANDO 3/15/2008 Thunderstorm Wind 50 kts. EG 0/0 $4,463 HERNANDO 7/31/2008 Thunderstorm Wind 50 kts. EG 0/0 $16,737 HERNANDO 8/7/2008 Thunderstorm Wind 50 kts. EG 0/0 $5,579 HERNANDO 6/12/2009 Thunderstorm Wind 61 kts. EG 0/0 $0 Horn Lake Horn Lake 8/5/1993 Thunderstorm Wind 0 kts. 0/0 $831 Horn Lake 11/5/1994 Thunderstorm Wind 0 kts. 0/0 $81,051 Horn Lake 10/27/1995 Thunderstorm Wind 0 kts. 0/0 $7,882 HORN LAKE 8/24/2002 Thunderstorm Wind -- 0/0 $13,354 HORN LAKE 8/18/2007 Thunderstorm Wind 50 kts. EG 0/0 $1,159 HORN LAKE 5/6/2009 Thunderstorm Wind 50 kts. EG 0/0 $0 HORN LAKE 6/12/2009 Thunderstorm Wind 63 kts. EG 0/0 $0 HORN LAKE 4/4/2011 Thunderstorm Wind 61 kts. EG 0/0 $0 HORN LAKE 8/24/2014 Thunderstorm Wind 50 kts. EG 0/0 $0 Olive Branch Olive Branch 6/9/1994 Thunderstorm Wind 53 kts. 0/0 $811 OLIVE BRANCH 6/27/1997 Thunderstorm Wind -- 0/0 $14,968 OLIVE BRANCH 1/21/1999 Thunderstorm Wind -- 0/0 $14,420 OLIVE BRANCH 5/21/2001 Thunderstorm Wind 80 kts. E 0/0 $135,650 OLIVE BRANCH 11/24/2001 Thunderstorm Wind -- 0/0 $33,912 B:35

36 Location Date Type Magnitude Deaths/Injuries Property Damage* OLIVE BRANCH 4/24/2002 Thunderstorm Wind -- 0/0 $1,335 OLIVE BRANCH 3/20/2004 Thunderstorm Wind 55 kts. EG 0/0 $12,718 OLIVE BRANCH 7/4/2004 Thunderstorm Wind 50 kts. EG 0/0 $12,718 OLIVE BRANCH 7/4/2005 Thunderstorm Wind 55 kts. EG 0/0 $12,301 OLIVE BRANCH 11/15/2005 Thunderstorm Wind 50 kts. EG 0/0 $1,230 OLIVE BRANCH 10/17/2007 Thunderstorm Wind 50 kts. EG 0/0 $6,952 OLIVE BRANCH 5/10/2008 Thunderstorm Wind 50 kts. EG 0/0 $11,158 OLIVE BRANCH 6/1/2008 Thunderstorm Wind 50 kts. EG 0/0 $33,474 OLIVE BRANCH 5/27/2009 Thunderstorm Wind 50 kts. EG 0/0 $16,797 OLIVE BRANCH 6/12/2009 Thunderstorm Wind 61 kts. EG 0/0 $0 OLIVE BRANCH 6/12/2009 Thunderstorm Wind 50 kts. EG 0/0 $0 OLIVE BRANCH 6/12/2009 Thunderstorm Wind 68 kts. MG 0/0 $0 OLIVE BRANCH 4/24/2010 Thunderstorm Wind 50 kts. EG 0/0 $0 OLIVE BRANCH 6/13/2011 Thunderstorm Wind 83 kts. EG 0/1 $3,204,015 OLIVE BRANCH 6/11/2012 Thunderstorm Wind 52 kts. EG 0/0 $0 OLIVE BRANCH ARPT 7/30/2012 Thunderstorm Wind 56 kts. MG 0/0 $0 OLIVE BRANCH 6/22/2014 Thunderstorm Wind 61 kts. EG 0/0 $0 Southaven SOUTH HAVEN 1/18/1996 Thunderstorm Wind -- 0/0 $15,311 SOUTH HAVEN 10/17/1996 Thunderstorm Wind -- 0/0 $7,656 SOUTH HAVEN 7/8/1997 Thunderstorm Wind -- 0/0 $1,497 SOUTH HAVEN 5/5/1999 Thunderstorm Wind -- 0/0 $36,050 SOUTH HAVEN 5/12/2000 Thunderstorm Wind -- 0/0 $6,975 SOUTH HAVEN 10/24/2001 Thunderstorm Wind -- 0/0 $13,565 SOUTH HAVEN 8/23/2003 Thunderstorm Wind 50 kts. EG 0/0 $1,306 SOUTH HAVEN 7/16/2004 Thunderstorm Wind 55 kts. EG 0/0 $1,272 SOUTH HAVEN 7/19/2005 Thunderstorm Wind 50 kts. EG 0/0 $6,150 SOUTH HAVEN 1/22/2012 Thunderstorm Wind 55 kts. EG 0/0 $5,232 SOUTH HAVEN 9/6/2012 Thunderstorm Wind 50 kts. EG 0/0 $0 Walls WALLS 11/7/1996 Thunderstorm Wind -- 0/0 $1,531 WALLS 5/20/2001 Thunderstorm Wind -- 0/0 $13,565 WALLS 5/20/2001 Thunderstorm Wind -- 0/0 $13,565 WALLS 1/31/2002 Thunderstorm Wind -- 0/0 $13,354 WALLS 11/6/2005 Thunderstorm Wind 65 kts. EG 0/0 $1,230 WALLS 5/10/2008 Thunderstorm Wind 61 kts. EG 0/0 $0 WALLS 7/31/2008 Thunderstorm Wind 50 kts. EG 0/0 $2,232 WALLS 4/19/2011 Thunderstorm Wind 50 kts. EG 0/0 $0 WALLS 6/7/2014 Thunderstorm Wind 52 kts. EG 0/0 $0 Unincorporated Area DE SOTO CO. 4/25/1961 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 9/6/1965 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 5/16/1966 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 4/24/1970 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 4/24/1970 Thunderstorm Wind 0 kts. 0/0 $0 B:36

37 Location Date Type Magnitude Deaths/Injuries Property Damage* DE SOTO CO. 11/19/1970 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 4/7/1972 Thunderstorm Wind 50 kts. 0/0 $0 DE SOTO CO. 5/11/1973 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 5/26/1975 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 2/21/1976 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 2/21/1976 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 2/23/1977 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 5/3/1979 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 8/28/1979 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 7/25/1981 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 6/30/1982 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 4/29/1984 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 6/17/1985 Thunderstorm Wind 52 kts. 0/0 $0 DE SOTO CO. 6/17/1985 Thunderstorm Wind 52 kts. 0/0 $0 DE SOTO CO. 3/12/1986 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 7/31/1986 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 6/12/1989 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 3/14/1990 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 5/21/1990 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 6/22/1990 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 3/27/1991 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 4/9/1991 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 7/2/1991 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 11/19/1991 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 6/10/1992 Thunderstorm Wind 54 kts. 0/0 $0 DE SOTO CO. 6/10/1992 Thunderstorm Wind 0 kts. 0/0 $0 DE SOTO CO. 6/25/1992 Thunderstorm Wind 0 kts. 0/0 $0 Lake Cormorant 5/18/1993 Thunderstorm Wind 0 kts. 0/0 $831 Nesbit 8/5/1993 Thunderstorm Wind 0 kts. 0/0 $8,313 N Portion 9/24/1993 Thunderstorm Wind 0 kts. 0/0 $831 INGRAMS MILL 2/27/1996 Thunderstorm Wind -- 0/0 $76,557 PLEASANT HILL 5/28/1996 Thunderstorm Wind -- 0/0 $3,062 PENTON 6/17/1997 Thunderstorm Wind -- 0/0 $1,497 COUNTYWIDE 6/5/1998 Thunderstorm Wind 65 kts. 0/0 $3,684,601 STONEWALL 11/24/2001 Thunderstorm Wind -- 0/0 $20,347 CEDARVIEW 11/26/2001 Thunderstorm Wind -- 0/0 $27,130 DE SOTO (ZONE) 9/26/2002 Wind 35 kts. E 0/0 $13,354 COCKRUM 6/11/2003 Thunderstorm Wind 60 kts. EG 0/0 $26,113 COUNTYWIDE 7/22/2003 Thunderstorm Wind 70 kts. EG 0/0 $2,219,572 EUDORA 8/23/2003 Thunderstorm Wind 50 kts. EG 0/0 $1,306 EUDORA 7/4/2004 Thunderstorm Wind 50 kts. EG 1/0 $12,718 COCKRUM 6/9/2005 Thunderstorm Wind 50 kts. EG 0/0 $1,230 DE SOTO (ZONE) 10/16/2006 Strong Wind 40 kts. EG 0/0 $1,192 DE SOTO (ZONE) 2/24/2007 Strong Wind 40 kts. EG 0/0 $3,476 DE SOTO (ZONE) 1/29/2008 Wind 50 kts. EG 0/0 $18,969 LAKE CORMORANT 3/15/2008 Thunderstorm Wind 50 kts. EG 0/0 $2,232 B:37

38 Location Date Type Magnitude Deaths/Injuries Property Damage* FREES CORNER 3/15/2008 Thunderstorm Wind 50 kts. EG 0/0 $1,116 CUB LAKE 5/2/2008 Thunderstorm Wind 50 kts. EG 0/0 $2,232 BRIGHT 5/2/2008 Thunderstorm Wind 50 kts. EG 0/0 $2,232 HANDY CORNER 5/10/2008 Thunderstorm Wind 63 kts. MG 0/0 $0 COCKRUM 5/24/2008 Thunderstorm Wind 60 kts. EG 0/0 $0 MINERAL WELLS 6/12/2008 Thunderstorm Wind 50 kts. EG 0/0 $11,158 MILLER 7/22/2008 Thunderstorm Wind 50 kts. EG 0/0 $4,463 LAKE CORMORANT 7/31/2008 Thunderstorm Wind 50 kts. EG 0/0 $2,232 DE SOTO (ZONE) 12/27/2008 Strong Wind 39 kts. EG 0/0 $22,316 LAKE CORMORANT 5/6/2009 Thunderstorm Wind 50 kts. EG 0/0 $0 LEWISBURG 5/27/2009 Thunderstorm Wind 50 kts. EG 0/0 $0 NESBIT 6/11/2009 Thunderstorm Wind 50 kts. EG 0/0 $0 EUDORA 6/12/2009 Thunderstorm Wind 50 kts. EG 0/0 $0 ALDENS 6/12/2009 Thunderstorm Wind 52 kts. EG 0/0 $0 DAYS 6/14/2009 Thunderstorm Wind 50 kts. EG 0/0 $0 COCKRUM 6/14/2009 Thunderstorm Wind 50 kts. EG 0/0 $0 MILLER 7/13/2009 Thunderstorm Wind 52 kts. EG 0/0 $0 EUDORA 6/17/2010 Thunderstorm Wind 50 kts. EG 0/0 $0 INGRAMS MILL 4/15/2011 Thunderstorm Wind 61 kts. EG 0/0 $0 LOVE 4/19/2011 Thunderstorm Wind 61 kts. EG 0/0 $0 HORN LAKE DESOTO ARP 4/25/2011 Thunderstorm Wind 50 kts. EG 0/0 $1,068 PLEASANT HILL 8/12/2011 Thunderstorm Wind 50 kts. EG 0/0 $0 LOVE 10/17/2012 Thunderstorm Wind 50 kts. EG 0/0 $418,541 EUDORA 12/21/2013 Thunderstorm Wind 50 kts. EG 0/0 $0 MARIENETTE 2/20/2014 Thunderstorm Wind 50 kts. EG 0/0 $0 PLEASANT HILL 4/4/2014 Thunderstorm Wind 56 kts. EG 0/0 $0 NESBIT 10/2/2014 Thunderstorm Wind 55 kts. MG 0/0 $0 *Property damage is reported in 2016 dollars; all damage may not have been reported. E = estimated; EG = estimated gust; ES = estimated sustained; MG = measured gust; MS = measured sustained Source: National Climatic Data Center PROBABILITY OF FUTURE OCCURRENCES Given the high number of previous events, it is certain that thunderstorm events, including straight-line wind events, will occur in the future. This results in a probability level of highly likely (100 percent annual probability) for the entire county. B.2.14 Tornado LOCATION AND SPATIAL EXTENT Tornadoes occur throughout the state of Mississippi, and thus in DeSoto County. Tornadoes typically impact a relatively small area, but damage may be extensive. Event locations are completely random and it is not possible to predict specific areas that are more susceptible to tornado strikes over time. Therefore, it is assumed that DeSoto County is uniformly exposed to this hazard. With that in mind, Figure B.12 shows B:38

39 tornado track data for many of the major tornado events that have impacted the county between 1950 and While no definitive pattern emerges from this data, some areas that have been impacted in the past may be potentially more susceptible in the future. FIGURE B.12: HISTORICAL TORNADO TRACKS IN DESOTO COUNTY Source: National Weather Service Storm Prediction Center HISTORICAL OCCURRENCES Tornadoes were at least partially responsible for three disaster declarations in DeSoto County in 1973, 2001, and According to the National Climatic Data Center, there have been a total of 24 recorded tornado events in DeSoto County since 1962 (Table B.24), resulting in almost $59.5 million (2016 dollars) in property damages In addition, 1 fatality and 105 injuries were reported. The magnitude of these tornadoes ranges from F0 to F3 and EF0 to EF2 in intensity, although an EF5 event is possible. Detailed information on historic tornado events can be found in Table B A complete listing of historical disaster declarations can be found in Section 4: Hazard Identification. 20 These tornado events are only inclusive of those reported by the National Climatic Data Center (NCDC) from 1950 through March It is likely that additional tornadoes have occurred in DeSoto County. As additional local data becomes available, this hazard profile will be amended. 21 Adjusted dollar values were calculated based on the average Consumer Price Index for a given calendar year. This index value has been calculated every year since For 2016, the May 2016 monthly index was used. B:39

40 Location TABLE B.24: SUMMARY OF TORNADO OCCURRENCES IN DESOTO COUNTY Number of Occurrences Deaths/Injuries Property Damage (2016) Annualized Property Losses Hernando 1 0/0 $811 $37 Horn Lake 2 0/0 $80,205 $3,646 Olive Branch 3 0/2 $4,725,170 $429,561 Southaven 0 0/0 $0 $0 Walls 0 0/0 $0 $0 Unincorporated Area 18 1/103 $54,663,585 $1,012,289 DESOTO COUNTY TOTAL Source: National Climatic Data Center 24 1/105 $59,469,771 $1,445,532 TABLE B.25: HISTORICAL TORNADO IMPACTS IN DESOTO COUNTY Location Date Magnitude Hernando Deaths/ Injuries Property Damage* Hernando 4/26/1994 F0 0/0 $811 Horn Lake Horn Lake 4/26/1994 F0 0/0 $8,105 HORN LAKE 1/22/1999 F0 0/0 $72,100 Olive Branch OLIVE BRANCH 3/22/2005 F0 0/0 $61,504 OLIVE BRANCH 3/22/2005 F1 0/1 $184,513 Details A tornado briefly touched down just northeast of Hernando. Some trees were blown down. A tornado touched down in the northern part of DeSoto County. Several tree tops were ripped off. A tornado touched down in Horn Lake. Five homes suffered serious structural damage while 100 other homes had lesser damage. The tornado touched down on the southwest edge of the Cherokee Valley Golf Course and moved northeast. A car wash and a Jiffy Lube had the glass blown out of their buildings. A large oak tree at the golf course was uprooted. Some shingles and small trees were blown down. The tornado touched down in the Alexandria Ridge subdivision in Olive Branch and moved northeast. One home suffered extensive roof damage. Another home had an air conditioner blown through one of the windows. Several other homes suffered minor shingle and fence damage. B:40

41 Location Date Magnitude Deaths/ Injuries Property Damage* OLIVE BRANCH 6/12/2009 EF2 0/1 $4,479,153 Southaven None Reported Walls None Reported Unincorporated Area DE SOTO CO. 4/28/1962 F2 0/1 $1,988, DE SOTO CO. 2/11/1965 F2 0/1 $190, DE SOTO CO. 6/30/1967 F1 0/0 $0 -- DE SOTO CO. 4/3/1968 F2 0/4 $0 -- DE SOTO CO. 5/16/1968 F2 0/7 $1,725, DE SOTO CO. 6/24/1969 F1 0/0 $0 -- DE SOTO CO. 4/24/1970 F3 0/5 $15, Details A tornado touched down at the truck weighing scales on way 78 about 1 mile southeast of Goodman Road in Olive Branch. The tornado had a non-continuous track to the east-northeast for 2.9 miles and ended a few hundred yards east of Hacks Cross Road about one half mile south of Goodman Road. The maximum estimated winds were 125 mph. There was widespread damage along the tornado track in Olive Branch. Numerous trees and power lines were knocked down. Four homes were destroyed while numerous other homes suffered some degree of damage. Streets that suffered the heaviest damage included Roberta Street, College Street, Blocker Street, Chickasaw Drive, Cherokee Drive, Sequoia Lane, Seminole Drive and Magnolia Drive. Several schools and public buildings were also damaged including the Olive Branch Elementary, Middle and Schools, the Chickasaw Elementary School, the Olive Branch Community Center and the Olive Branch City Shop. The Olive Branch Middle School alone suffered $500,000 in damage. The tornado cleanup costs totaled $350,000 for the city of Olive Branch. There was one minor injury associated with the tornado in Olive Branch. B:41

42 Location Date Magnitude Deaths/ Injuries Property Damage* DE SOTO CO. 11/27/1973 F1 0/10 $1,352,680 DE SOTO CO. 11/27/1973 F1 0/15 $1,352,680 Details Three tornadoes moved northeastward from about 4 miles northwest of Eudora into Horn Lake and Southaven areas. Newspaper said "damage was very severe in a 2-mile-wide belt through county." The 3 damage paths were separated by mile-wide sections with little or no damage. 212 homes destroyed. 2 were fixed dwellings, 210 were mobile homes. 75 persons were injured and there was 1 fatality. At least 13 persons were hospitalized. Damage estimated $1,000, to $1,500, At least 3 schools damaged. (a) The first tornado damage path started on Wilson Mill Road, about 1 mile east of Texas Gas pumping station, extended northeastward 4-1/2 miles a little past intersection of way 301 and Austin Road. (b) A second damage path began near the intersection of Star Landing Road and way 301 and extended about 8 miles northeastward through eastern Horn Lake to the Southaven Elementary School in Central Southaven. (c) The third damage path was shorter and less defined, about 2-3/4 miles long but included the DeSoto Woods and Redwood Estates mobile homes where most injuries occurred. Three tornadoes moved northeastward from about 4 miles northwest of Eudora into Horn Lake and Southaven areas. Newspaper said "damage was very severe in a 2-mile-wide belt through county." The 3 damage paths were separated by mile-wide sections with little or no damage. 212 homes destroyed. 2 were fixed dwellings, 210 were mobile homes. 75 persons were injured and there was 1 fatality. At least 13 persons were hospitalized. Damage estimated $1,000, to $1,500, At least 3 schools damaged. (a) The first tornado damage path started on Wilson Mill Road, about 1 mile east of Texas Gas pumping station, extended northeastward 4-1/2 miles a little past intersection of way 301 and Austin Road. (b) A second damage path began near the intersection of Star Landing Road and way 301 and extended about 8 miles northeastward through eastern Horn Lake to the Southaven Elementary School in Central Southaven. (c) The third damage path was shorter and less defined, about 2-3/4 miles long but included the DeSoto Woods and Redwood Estates mobile homes where most injuries occurred. B:42

43 Location Date Magnitude Deaths/ Injuries Property Damage* DE SOTO CO. 11/27/1973 F2 1/50 $1,352,680 DE SOTO CO. 3/12/1986 F1 0/0 $547, DE SOTO CO. 1/19/1988 F2 0/1 $5,076,839 Details Three tornadoes moved northeastward from about 4 miles northwest of Eudora into Horn Lake and Southaven areas. Newspaper said "damage was very severe in a 2-mile-wide belt through county." The 3 damage paths were separated by mile-wide sections with little or no damage. 212 homes destroyed. 2 were fixed dwellings, 210 were mobile homes. 75 persons were injured and there was 1 fatality. At least 13 persons were hospitalized. Damage estimated $1,000, to $1,500, At least 3 schools damaged. (a) The first tornado damage path started on Wilson Mill Road, about 1 mile east of Texas Gas pumping station, extended northeastward 4-1/2 miles a little past intersection of way 301 and Austin Road. (b) A second damage path began near the intersection of Star Landing Road and way 301 and extended about 8 miles northeastward through eastern Horn Lake to the Southaven Elementary School in Central Southaven. (c) The third damage path was shorter and less defined, about 2-3/4 miles long but included the DeSoto Woods and Redwood Estates mobile homes where most injuries occurred. A tornado moved northeast at 55 mph and touched down 4 separate times in a 9.5 mile stretch. Near the middle portion of the track, the tornado set down for 3 miles and inflicted its worst damage in subdivision south of Southaven. In total, 4 homes were destroyed, 10 had major damage and 79 minor damage. Damage was estimated at on half million dollars. The tornado also derailed 14 cars of a train. Other outbuildings and fences also received heavy damage. Total damage from the tornado was estimated at 1.2 million dollars. Nesbit 8/5/1993 F0 0/0 $8,313 Numerous trees were knocked down. LEWISBURG 11/24/2001 F2 0/9 $2,577,348 NORFOLK 2/5/2008 EF0 0/0 $55,790 The tornado began just southwest of Lewisburg in eastern De Soto county and moved northeast. Nineteen homes were destroyed and 119 homes were damaged. Numerous trees were also knocked down. A tornado touched down near Old way 61 and damaged a farm building roof. The tornado tracked northeast for a little more than 2 miles, lifting along Norfolk Road. A pivot irrigation system was damaged and power poles were knocked down along Norfolk Road. B:43

44 Location Date Magnitude Deaths/ Injuries Property Damage* HORN LAKE DESOTO ARP 2/5/2008 EF2 0/0 $31,688,840 MILLER 7/30/2009 EF2 0/0 $6,718,729 NESBIT 5/2/2010 EF0 0/0 $11,017 *Property damage is reported in 2016 dollars; all damage may not have been reported. Source: National Climatic Data Center Details A tornado touched down at Southaven School and tracked northeast crossing into Shelby County, Tennessee, northeast of the intersection of Stateline Road and Airways Boulevard. Roughly 30 windows were blown out of the School. The school also sustained minor roof damage. Damage at the high school was classified EF-0. Many homes in the Carriage Hills subdivision sustained minor damages as well. Further northeast, more significant damage occurred near the intersection of Stateline Road and Airways Boulevard in the warehouse area. Three warehouses were destroyed including the Cooper Lighting Plant. A gas station was damaged as well. Damage was classified as EF- 2 in this area. Numerous trees, power poles, and lines were knocked down. Minor roof damage occurred along the path as well. A tornado touched down on way 305, four tenths of a mile south of College Road, southeast of Olive Branch. The tornado moved northeast on a non-continuous track. Several subdivisions had numerous trees and power lines knocked down. Some of which fell onto houses damaging them. The hardest hit area was in the Bethel Park Subdivision. Seven homes were destroyed, 15 homes sustained major damage while at least 113 other homes received minor damage including damage such as minor roof or shingle damage. In addition, one business sustained major damage and another business sustained minor damage. The tornado lifted just east of the intersection of Center Hill Road and Knightsbridge Road. A weak tornado touched down just north of Interstate 69 near Tulane Road and traveled northeast for about 1 mile before lifting near the Nesbit Road. Several very large trees were knocked down and a couple of them were snapped off. Some shingle damage was noted as well. There have been several significant tornado events in DeSoto County. The text below describes one of the major events and associated impacts on the county. From April 25 to 28, 2011, the largest tornado outbreak ever recorded affected the Southern, Midwestern, and Northeastern U.S., leaving catastrophic destruction in its wake, especially across the states of Alabama and Mississippi. Although no tornadoes were reported in DeSoto County, it is notable that B:44

45 surrounding areas experienced much higher magnitude tornadoes and that these are possible in the county. PROBABILITY OF FUTURE OCCURRENCES According to historical information, tornado events pose a significant threat to DeSoto County. The probability of future tornado occurrences affecting DeSoto County is highly likely (100 percent annual probability). B.2.15 Winter Storm and Freeze LOCATION AND SPATIAL EXTENT Nearly the entire continental United States is susceptible to winter storm and freeze events. Some ice and winter storms may be large enough to affect several states, while others might affect limited, localized areas. The degree of exposure typically depends on the normal expected severity of local winter weather. DeSoto County is not accustomed to severe winter weather conditions and seldom receives severe winter weather, even during the winter months. Events tend to be mild in nature; however, this creates a situation where even relatively small accumulations of snow, ice, or other wintery precipitation can lead to losses and damage due to the fact that these events are not commonplace. Given the atmospheric nature of the hazard, the entire county has uniform exposure to a winter storm. HISTORICAL OCCURRENCES Winter weather has resulted in one disaster declaration in DeSoto County in According to the National Climatic Data Center, there have been a total of 34 recorded winter storm events in DeSoto County since 1996 (Table B.26). 23 These events resulted in almost $50,000 (2016 dollars) in damages. 24 Detailed information on the recorded winter storm events can be found in Table B.27. Location TABLE B.26: SUMMARY OF WINTER STORM EVENTS IN DESOTO COUNTY Number of Occurrences Deaths/Injuries Property Damage (2016) Annualized Property Losses DeSoto County 34 0/0 $49,703 $2,485 Source: National Climatic Data Center Hernando TABLE B.27: HISTORICAL WINTER STORM IMPACTS IN DESOTO COUNTY Location Date Type Deaths/Injuries Property Damage* None Reported Horn Lake None Reported A complete listing of historical disaster declarations can be found in Section 4: Hazard Identification. 23 These ice and winter storm events are only inclusive of those reported by the National Climatic Data Center (NCDC) from 1996 through April It is likely that additional winter storm conditions have affected DeSoto County. 24 Adjusted dollar values were calculated based on the average Consumer Price Index for a given calendar year. This index value has been calculated every year since For 2015, the June 2015 monthly index was used. B:45

46 Olive Branch Location Date Type Deaths/Injuries Property Damage* None Reported Southaven None Reported Walls None Reported Unincorporated Area DE SOTO (ZONE) 2/1/1996 Winter Storm 0/0 $30,623 DE SOTO (ZONE) 1/15/1998 Winter Storm 0/0 $0 DE SOTO (ZONE) 12/22/1998 Ice Storm 0/0 $1,474 DE SOTO (ZONE) 1/27/2000 Heavy Snow 0/0 $0 DE SOTO (ZONE) 12/13/2000 Ice Storm 0/0 $13,951 DE SOTO (ZONE) 2/5/2002 Winter Storm 0/0 $0 DE SOTO (ZONE) 12/22/2004 Winter Storm 0/0 $1,272 DE SOTO (ZONE) 2/10/2006 Winter Storm 0/0 $1,192 DE SOTO (ZONE) 2/18/2006 Winter Storm 0/0 $1,192 DE SOTO (ZONE) 2/1/2007 Winter Weather 0/0 $0 DE SOTO (ZONE) 4/6/2007 Frost/freeze 0/0 $0 DE SOTO (ZONE) 4/7/2007 Frost/freeze 0/0 $0 DE SOTO (ZONE) 1/25/2008 Winter Weather 0/0 $0 DE SOTO (ZONE) 3/7/2008 Winter Storm 0/0 $0 DE SOTO (ZONE) 3/7/2008 Winter Storm 0/0 $0 DE SOTO (ZONE) 2/28/2009 Winter Weather 0/0 $0 DE SOTO (ZONE) 3/1/2009 Winter Storm 0/0 $0 DE SOTO (ZONE) 1/29/2010 Winter Storm 0/0 $0 DE SOTO (ZONE) 2/8/2010 Winter Storm 0/0 $0 DE SOTO (ZONE) 2/14/2010 Winter Weather 0/0 $0 DE SOTO (ZONE) 1/9/2011 Winter Storm 0/0 $0 DE SOTO (ZONE) 1/20/2011 Winter Weather 0/0 $0 DE SOTO (ZONE) 2/7/2011 Winter Weather 0/0 $0 DE SOTO (ZONE) 2/9/2011 Winter Storm 0/0 $0 DE SOTO (ZONE) 11/28/2011 Winter Weather 0/0 $0 DE SOTO (ZONE) 12/7/2011 Winter Weather 0/0 $0 DE SOTO (ZONE) 12/6/2013 Winter Weather 0/0 $0 DE SOTO (ZONE) 12/7/2013 Winter Weather 0/0 $0 DE SOTO (ZONE) 3/2/2014 Winter Weather 0/0 $0 DE SOTO (ZONE) 2/16/2015 Winter Storm 0/0 $0 DE SOTO (ZONE) 2/20/2015 Winter Weather 0/0 $0 DE SOTO (ZONE) 2/25/2015 Winter Storm 0/0 $0 DE SOTO (ZONE) 3/4/2015 Winter Storm 0/0 $0 DE SOTO (ZONE) 1/22/2016 Winter Weather 0/0 $0 *Property damage is reported in 2016 dollars; all damage may not have been reported. Source: National Climatic Data Center B:46

47 There have been several severe winter weather events in DeSoto County. The text below describes three of the major events and associated impacts on the county. Similar impacts can be expected with severe winter weather. February 1994 A damaging ice storm with freezing rain accumulations of 3 to 6 inches occurred across north Mississippi from February Most estimates calculate this storm as the worst on record since 1951 with damages occurring across parts of Arkansas, Tennessee, Alabama, Louisiana, and Texas, as well as 26 counties in Mississippi, which sustained damages of roughly $300 million. According to power companies, more than 200,000 homes were left without power at the height of the storm, and water provides estimate nearly 175,000 homes were without water during this time period. Agriculture also took an especially hard hit as nearly 5 percent of the state s pecan trees were destroyed. 25 December 1998 Much of north Mississippi was hit with an ice storm. Most counties reported between 0.25 to 0.5 inches of ice on their roads with some locations in the southern part of the region reporting as much as 3 inches of ice. The ice caused numerous power outages and brought down many trees and power lines. Thousands of people in north Mississippi were without power, some for as long as one week. Christmas travel was severely hampered for several days with motorists stranded at airports, bus stations, and truck stops. Travel did not return to normal until after Christmas in some locations. January 2000 A winter storm brought a swath of heavy snow across north central Mississippi. The snow began falling over western portions of the area during the early morning of the 27th and spread eastward during the day. The snow was heavy at times and did not end until the morning of the 28th. Snowfall amounts generally ranged from 4 to 10 inches. The heaviest amounts fell along the way 82 corridor from Greenville to Starkville where isolated snow depths of 12 inches were reported. Damage from the heavy snow was relatively minimal with reports limited to a few collapsed roofs and downed trees. Power outages were sporadic, but travelling was more than just an inconvenience as numerous reports of vehicles running off the road were received. Winter storms throughout the planning area have several negative externalities including hypothermia, cost of snow and debris cleanup, business and government service interruption, traffic accidents, and power outages. Furthermore, citizens may resort to using inappropriate heating devices that could to fire or an accumulation of toxic fumes. PROBABILITY OF FUTURE OCCURRENCES Winter storm events will continue to occur in DeSoto County. Based on historical information, the probability is likely (between 10 and 100 percent annual probability). B.2.16 Conclusions on Hazard Risk The hazard profiles presented in this subsection were developed using best available data and result in what may be considered principally a qualitative assessment as recommended by FEMA in its How-to guidance document titled Understanding Your Risks: Identifying Hazards and Estimating Losses (FEMA 25 Pfost, Russell L. Disastrous Mississippi Ice Storm of National Weather Service Forecast Office. Jackson, Mississippi. B:47

48 Publication 386-2). It relies heavily on historical and anecdotal data, stakeholder input, and professional and experienced judgment regarding observed and/or anticipated hazard impacts. It also carefully considers the findings in other relevant plans, studies, and technical reports. HAZARD EXTENT Table B.28 describes the extent of each natural hazard identified for DeSoto County. The extent of a hazard is defined as its severity or magnitude, as it relates to the planning area. Flood-related Hazards Dam and Levee Failure Erosion TABLE B.28: EXTENT OF DESOTO COUNTY HAZARDS Dam Failure extent is defined using the Mississippi Department of Environmental Quality criteria (Table 5.3). Twenty-six dams are classified as high-hazard in DeSoto County. The extent of erosion can be defined by the measurable rate of erosion that occurs. There are no erosion rate records located in DeSoto County. Some areas of minimal erosion have been identified by local coordinators, but no major areas of severe erosion were noted. Flood extent can be measured by the amount of land and property in the floodplain as well as flood height and velocity. The amount of land in the floodplain accounts for 24.5 percent of the total land area in DeSoto County. Flood Fire-related Hazards Drought Lightning Wildfire Flood depth and velocity are recorded via United States Geological Survey stream gages throughout the region. While a gage does not exist for each participating jurisdiction, there is one at or near many areas. The greatest peak discharge recorded for the county was at the Coldwater River near Arkabutla Dam on January 22, Water reached a discharge of 30,200 cubic feet per second. The highest stream gage height was also on the Coldwater River near Arkabutla Dam with a height that was recorded at feet on February 16, Drought extent is defined by the U.S. Drought Monitor Classifications which include Abnormally Dry, Moderate Drought, Severe Drought, Extreme Drought, and Exceptional Drought. According to the U.S. Drought Monitor Classifications, the most severe drought condition is Exceptional. DeSoto County has received this ranking once over the 17-year reporting period. According to the Vaisala s flash density map (Figure 5.8), DeSoto County is located in an area that experiences 4 to 12 lightning flashes per square kilometer per year. It should be noted that future lightning occurrences may exceed these figures. Wildfire data was provided by the Mississippi Forestry Commission and is reported annually by county from The greatest number of fires to occur in DeSoto County in any year was 3 in The greatest number of acres to burn in the county in a single year occurred in 2014 when 68 acres were burned. Although this data lists the extent that has occurred, larger and more frequent wildfires are possible throughout the county. B:48

49 Geologic Hazards Earthquake Landslide Land Subsidence/ Sinkhole Wind-related Hazards Extreme Heat Hailstorm Hurricane and Tropical Storm Severe Thunderstorm/ Wind Tornado Winter Storm and Freeze Earthquake extent can be measured by the Richter Scale (Table 5.15), the Modified Mercalli Intensity (MMI) scale (Table 5.16), and the distance of the epicenter from DeSoto County. According to data provided by the National Geophysical Data Center, the greatest earthquake to impact the county had a MMI of IV (moderate) and a Richter Scale magnitude of 5.3 (reported on November 9, 1968). The epicenter of this earthquake was located km away. As noted above in the landslide profile, there is no extensive history of landslides in DeSoto County and landslide events typically occur in isolated areas. This provides a challenge when trying to determine an accurate extent for the landslide hazard. However, when using USGS landslide susceptibility index, extent can be measured with incidence, which is low across half of the county. The remainder of the county has moderate incidence. There is also low susceptibility throughout some of the county but there are areas of high susceptibility in the northwestern corner and center of the county. The extent of land subsidence can be defined by the measurable rate of subsidence that occurs. There are no subsidence rate records located in DeSoto County nor is there any significant historical record of events. The largest potential event might be as a large as 10,000 cubic yards. The extent of extreme heat can be measured by the record high temperature recorded. Official long term temperature records are not kept for any areas in DeSoto County. However, the highest recorded temperature in Tunica (southwest of the county) was 106 F in Hail extent can be defined by the size of the hail stone. The largest hail stone reported in DeSoto County was 2.0 inches (last reported on November 15, 2005). It should be noted that future events may exceed this. Hurricane extent is defined by the Saffir-Simpson Scale which classifies hurricanes into Category 1 through Category 5 (Table 5.23). The greatest classification of hurricane to traverse directly through DeSoto County was an Unnamed 1888 Storm which carried tropical force winds of 60 knots upon arrival in the county. Thunderstorm extent is defined by the number of thunder events and wind speeds reported. According to a 61-year history from the National Climatic Data Center, the strongest recorded wind event in DeSoto County was reported on June 13, 2011 at 83 knots (approximately 96 mph). It should be noted that future events may exceed these historical occurrences. Tornado hazard extent is measured by tornado occurrences in the US provided by FEMA (Figure 5.21) as well as the Fujita/Enhanced Fujita Scale (Tables 5.28 and 5.29). The greatest magnitude reported in DeSoto County was an F3 (reported on April 24, 1970). The extent of winter storms can be measured by the amount of snowfall received (in inches). The greatest snowfall reported in Olive was 14.3 inches in PRIORITY RISK INDEX RESULTS In order to draw some meaningful planning conclusions on hazard risk for DeSoto County, the results of the hazard profiling process were used to generate countywide hazard classifications according to a B:49

50 Priority Risk Index (PRI). More information on the PRI and how it was calculated can be found in Section Table B.29 summarizes the degree of risk assigned to each category for all initially identified hazards based on the application of the PRI. Assigned risk levels were based on the detailed hazard profiles developed for this subsection, as well as input from the Regional Hazard Mitigation Council. The results were then used in calculating PRI values and making final determinations for the risk assessment. Hazard Flood-related Hazards TABLE B.29: SUMMARY OF PRI RESULTS FOR DESOTO COUNTY Category/Degree of Risk Probability Impact Spatial Extent Warning Time Duration PRI Score Dam Failure and Levee Failure Unlikely Critical Large Less than 6 hours Less than 6 hours 2.5 Erosion Likely Minor Small More than 24 hours More than 1 week 2.1 Flood ly Likely Critical Moderate 6 to 12 hours Less than 24 hours 3.2 Fire-related Hazards Drought Likely Limited Large More than 24 hours More than 1 week 2.8 Lightning ly Likely Limited Small 6 to 12 hours Less than 6 hours 2.6 Wildfire ly Likely Minor Small Less than 6 hours Less than 1 week 2.6 Geologic Hazards Earthquake Likely Critical Large Less than 6 hours Less than 6 hours 3.1 Landslide Possible Minor Small Less than 6 hours Less than 24 hours 1.9 Land Subsidence/Sinkhole Possible Minor Small Less than 6 hours Less than 24 hours 1.9 Wind-related Hazards Extreme Heat Likely Minor Large More than 24 hours More than 1 week 2.5 Hailstorm ly Likely Limited Moderate 6 to 12 hours Less than 6 hours 2.8 Hurricane and Tropical Storm Possible Limited Large More than 24 hours Less than 24 hours 2.3 Severe Thunderstorm/ Wind ly Likely Critical Moderate 6 to 12 hours Less than 6 hours 3.1 Tornado ly Likely Catastrophic Small Less than 6 hours Less than 6 hours 3.3 Winter Storm and Freeze Likely Limited Moderate More than 24 hours Less than 1 week 2.5 B.2.17 Final Determinations on Hazard Risk The conclusions drawn from the hazard profiling process for DeSoto County, including the PRI results and input from the Regional Hazard Mitigation Council, resulted in the classification of risk for each identified hazard according to three categories: Risk, Moderate Risk, and Low Risk (Table B.30). For purposes of these classifications, risk is expressed in relative terms according to the estimated impact that a hazard will have on human life and property throughout all of DeSoto County. A more quantitative analysis to estimate potential dollar losses for each hazard has been performed separately, and is described in Section 6: Vulnerability Assessment and below in Section B.3. It should be noted that although some hazards are classified below as posing low risk, their occurrence of varying or unprecedented magnitudes B:50

51 is still possible in some cases and their assigned classification will continue to be evaluated during future plan updates. TABLE B.30: CONCLUSIONS ON HAZARD RISK FOR DESOTO COUNTY HIGH RISK MODERATE RISK LOW RISK Tornado Flood Severe Thunderstorm/ Wind Earthquake Hailstorm Drought Lightning Wildfire Dam and Levee Failure Extreme Heat Winter Storm and Freeze Hurricane and Tropical Storm Erosion Landslide Land Subsidence/Sinkhole B.3 DESOTO COUNTY VULNERABILITY ASSESSMENT This subsection identifies and quantifies the vulnerability of DeSoto County to the significant hazards previously identified. This includes identifying and characterizing an inventory of assets in the county and assessing the potential impact and expected amount of damages caused to these assets by each identified hazard event. More information on the methodology and data sources used to conduct this assessment can be found in Section 6: Vulnerability Assessment. B.3.1 Asset Inventory Table B.31 lists the estimated number of improved properties and the total value of improvements for DeSoto County and its participating jurisdictions (study area of vulnerability assessment). Because digital parcel data was not available for most communities, data obtained from Hazus-MH 3.1 inventory was utilized to complete the analysis. TABLE B.31: IMPROVED PROPERTY IN DESOTO COUNTY Location Counts of Improved Property Total Value of Improvements Hernando 6,576 $1,876,565,000 B:51

52 Location Counts of Improved Property Total Value of Improvements Horn Lake 8,470 $2,097,067,000 Olive Branch 12,779 $3,953,300,000 Southaven 19,594 $5,566,173,000 Walls 892 $227,950,000 Unincorporated Area 10,567 $2,663,858,000 DESOTO COUNTY TOTAL 58,878 $16,384,913,000 Source: Hazus-MH 3.1 Table B.32 lists the fire stations, police stations, medical care facilities, emergency operations centers (EOCs), schools, shelters, government buildings, water/utility infrastructure, and other facilities located in DeSoto County according to Hazus-MH Version 3.1 data that was reviewed and updated by local officials. In addition, Figure B.13 shows the locations of critical facilities in DeSoto County. Table B.42, at the end of this subsection, shows a complete list of the critical facilities by name, as well as the hazards that affect each facility. As noted previously, this list is not all-inclusive and only includes information provided through Hazus which was updated, as best as possible, with local knowledge. Location TABLE B.32: CRITICAL FACILITY INVENTORY IN DESOTO COUNTY Fire Stations Police Stations Medical Care EOC Schools Gov t* Water/ Utility* Shelter* Other* Hernando Horn Lake Olive Branch Southaven Walls Unincorporated Area DESOTO COUNTY TOTAL *All counties were not able to attain information on these facility types, however, this should not imply that these counties do not have any of these types of facilities. Instead, it should be noted that as this information is collected, it will be incorporated in future updates of the plan. Source: Hazus-MH 3.1, Local Officials B:52

53 FIGURE B.13: CRITICAL FACILITY LOCATIONS IN DESOTO COUNTY Source: Hazus-MH 3.1, Local Officials B.3.2 Social Vulnerability In addition to identifying those assets potentially at risk to identified hazards, it is important to identify and assess those particular segments of the resident population in DeSoto County that are potentially at risk to these hazards. Table B.33 lists the population by jurisdiction according to U.S. Census 2010 population estimates. The total population in DeSoto County according to Census data was 161,252 persons. Additional population estimates are presented above in Section B.1. TABLE B.33: TOTAL POPULATION IN DESOTO COUNTY Location Total 2010 Population Hernando 14,090 Horn Lake 26,066 Olive Branch 33,484 Southaven 48,982 Walls 1,162 B:53

54 Location Total 2010 Population Unincorporated Area 37,468 DESOTO COUNTY TOTAL 161,252 Source: United States Census Bureau, 2010 Census In addition, Figure B.14 illustrates the population density per square kilometer by census tract as it was reported by the U.S. Census Bureau in As can be seen in the figure, the population is spread out with concentrations in large municipal areas such as Horn Lake and Olive Branch. FIGURE B.14: POPULATION DENSITY IN DESOTO COUNTY Source: United States Census Bureau, 2010 Census B.3.3 Development Trends and Changes in Vulnerability Since the previous county hazard mitigation plan was approved, DeSoto County has experienced limited growth and development. Table B.34 shows the number of building units constructed since 2010 according to the U.S. Census American Community Survey. B:54

55 TABLE B.34: BUILDING COUNTS FOR DESOTO COUNTY Jurisdiction Total Housing Units (2014) Units Built 2010 or later % Building Stock Built Post-2010 Hernando 5, % Horn Lake 9, % Olive Branch 13, % Southaven 19, % Walls % Unincorporated Area 14, % DESOTO COUNTY TOTAL 62,703 1, % Source: United States Census Bureau, American Community Survey 5-Year Estimates Table B.35 shows population growth estimates for the county from 2010 to 2014 based on the U.S. Census American Community Survey. Jurisdiction TABLE B.35: POPULATION GROWTH FOR DESOTO COUNTY Population Estimates % Change Hernando 13,253 13,679 14,117 14,437 14, % Horn Lake 25,495 25,901 26,120 26,350 26, % Olive Branch 31,910 32,796 33,484 34,050 34, % Southaven 46,743 48,005 48,981 49,728 50, % Walls , % Unincorporated Area 36,730 37,405 38,109 38,496 39, % DESOTO COUNTY TOTAL 154, , , , , % Source: United States Census Bureau, , , , , and American Community Survey 5-Year Estimates Based on the data above, there has been a low rate of residential development and population growth in the county since However, it is notable that the City of Hernando has experienced a slightly higher rate of development compared to the rest of the county, resulting in an increased number of structures that are vulnerable to the potential impacts of the identified hazards. Additionally, there was a substantial rate of population growth in the Town of Walls. As a result, there are now greater numbers of people exposed to the identified hazards in some areas. Therefore, development and population growth have impacted the county s vulnerability since the previous local hazard mitigation plan was approved and there has been a slight increase in the overall vulnerability as well as a significant increase in certain areas and communities. It is also important to note that as development increases in the future, greater populations and more structures and infrastructure will be exposed to potential hazards if development occurs in the floodplains, landside susceptibility areas, or high wildfire risk areas. B:55

56 B.3.4 Vulnerability Assessment Results As noted in Section 6: Vulnerability Assessment, only hazards with a specific geographic boundary, available modeling tool, or sufficient historical data allow for further analysis. Those results, specific to DeSoto County, are presented here. All other hazards are assumed to impact the entire planning region (drought, extreme heat, hailstorm, lightning, severe thunderstorm/high wind, tornado, and winter storm) or, due to lack of data, analysis would not lead to credible results (dam and levee failure, erosion, and land subsidence/sinkhole). The total county exposure, and thus risk to these hazards, was presented in Table B.31. The hazards to be further analyzed in this subsection include: flood, landslide, wildfire, earthquake, and hurricane and tropical storm winds. The annualized loss estimate for all hazards is presented near the end of this subsection in Table B.41. FLOOD Historical evidence indicates that DeSoto County is susceptible to flood events. A total of 60 flood events have been reported by the National Climatic Data Center resulting in $11.8 million (2016 dollars) in property damage and two fatalities. On an annualized level, these damages amounted to $814,334 for DeSoto County. In order to assess flood risk, a GIS-based analysis was used to estimate exposure to flood events using Digital Flood Insurance Rate Map (DFIRM) data in combination with improved property records for the county. The determination of value at-risk (exposure) was calculated using GIS analysis by summing the values for improved properties that were located within an identified floodplain. Due to a lack of digital parcel data in most counties, it was determined that an analysis using the inventory from Hazus-MH 3.1 would be used, though it should be noted that the data will merely be an estimation and may not reflect actual counts or values located in the floodplain. Indeed, in almost all cases, this analysis likely overestimates the amount of property at risk. Table B.36 presents the potential at-risk property. Both the number of parcels and the approximate value are presented. TABLE B.36: ESTIMATED EXPOSURE OF PROPERTY TO THE FLOOD HAZARD 26 Location Approx. Number of Improvements 1.0-percent ACF Approx. Improved Value Hernando 2,015 $560,554,000 Horn Lake 2,233 $588,993,000 Olive Branch 2,979 $1,057,233,000 Southaven 7,031 $2,064,184,000 Walls 832 $207,184,000 Unincorporated Area 50,82 $1,281,465,000 DESOTO COUNTY TOTAL 20,172 $5,759,613,000 Source: Federal Emergency Management Agency DFIRM and Hazus MH As noted in Section 6.4, no building-specific data, such as building footprints, was available to determine buildings at risk. As a result of this data limitation, at-risk census block building counts and values of the structures were used. B:56

57 Social Vulnerability Figure B.15 is presented to gain a better understanding of at-risk population by evaluating census tract level population data against mapped floodplains. There are areas of concern in several of the population centers. Indeed, nearly every incorporated municipality is potentially at risk of being impacted by flooding in some areas of its jurisdiction. Therefore, further investigation in these areas may be warranted. FIGURE B.15 : POPULATION DENSITY NEAR FLOODPLAINS IN DESOTO COUNTY Source: Federal Emergency Management Agency DFIRM, United States Census 2010 Critical Facilities The critical facility analysis revealed that there are five critical facilities located in the floodplain. (Please note, as previously indicated, this analysis does not consider building elevation, which may negate risk.) All of these facilities are located in the 1.0 percent annual chance flood zone, and they include 2 fire stations and 3 schools. A list of specific critical facilities and their associated risk can be found in Table B.42 at the end of this subsection. In conclusion, a flood has the potential to impact many existing and future buildings, facilities, and populations in DeSoto County, though some areas are at a higher risk than others. All types of structures in a floodplain are at-risk, though elevated structures will have a reduced risk. Such site-specific vulnerability determinations are outside the scope of this assessment but may be considered during B:57

58 future plan updates. Furthermore, areas subject to repetitive flooding should be analyzed for potential mitigation actions. LANDSLIDE Steeper topography in some areas of DeSoto County makes the planning area susceptible to landslides. Although no major landslide incidents have been reported in the county, it should be noted that United States Geological Survey information on historic events is not well-documented so the data may be incomplete. There may be additional historical landslide occurrences that were not reported. In order to complete the vulnerability assessment for landslides in DeSoto County, GIS analysis was used. The potential dollar value of exposed property can be determined using the USGS Landslide Susceptibility Index (detailed in Section 5: Hazard Profiles), census block data from Hazus or countylevel tax parcel data, and GIS analysis. Table B.37 presents the potential at-risk property where available. Only a portion of the region is identified as being in a moderate incidence/high susceptibility or low incidence/high susceptibility area by the USGS landslide data. These incidence levels were used to identify areas of concern for the analysis below. TABLE B.37: TOTAL POTENTIAL AT-RISK PARCELS FOR THE LANDSLIDE HAZARD Location Low Incidence/ Susceptibility Area Approx. Number of Improvements Approx. Improved Value Moderate Incidence/ Susceptibility Area Approx. Number of Improvements Approx. Improved Value Hernando 0 $0 6,576 $1,876,565,000 Horn Lake 0 $0 8,094 $1,990,575,000 Olive Branch 0 $0 2,219 $614,236,000 Southaven 0 $0 19,498 $5,540,560,000 Walls 119 $36,656, $47,740,000 Unincorporated Area 645 $127,223,000 3,649 $924,249,000 DESOTO COUNTY TOTAL Source: United States Geological Survey and Hazus-MH $163,879,000 40,211 $10,993,925,000 Social Vulnerability Given low incidence across the most of the county, it is assumed that the total population is at relatively low risk. However, some populations in the western and central part of the county are considered at slightly higher risk due to their location in areas of high susceptibility. Critical Facilities There are no critical facilities located in a low incidence/high susceptibility area. Several critical facilities are located in the moderate incidence/high susceptibility area. There are 50 critical facilities located in this zone. This includes 1 EOC, 14 fire stations, 1 medical care facility, 6 police stations, and 28 schools. A list of specific critical facilities and their associated risk can be found in Table B.42 at the end of this subsection. B:58

59 In conclusion, a landslide has the potential to impact all existing and future buildings, critical facilities, and populations in DeSoto County. Specific vulnerabilities for DeSoto County assets will be greatly dependent on their individual design and the mitigation measures in place where appropriate. Such site-specific vulnerability determinations are outside the scope of this assessment but will be considered during future plan updates if data becomes available. WILDFIRE Although historical evidence indicates that DeSoto County is susceptible to wildfire events, there are few reports which include information on historic dollar losses. Therefore, it is difficult to calculate a reliable annualized loss figure. Annualized loss is considered negligible though it should be noted that a single event could result in significant damages throughout the county. To estimate exposure to wildfire, building data was obtained from Hazus-MH 3.1 for most counties which includes information that has been aggregated at the census block level and which has been deemed useful for analyzing wildfire vulnerability. However, it should be noted that the accuracy of Hazus data is somewhat lower than that of parcel data. For the critical facility analysis, areas of concern were intersected with critical facility locations. Figure B.16 shows the Wildland Urban Interface Risk Index (WUIRI) data, which is a data layer that shows a rating of the potential impact of a wildfire on people and their homes. The key input, Wildland Urban Interface (WUI), reflects housing density (houses per acre) consistent with Federal Register National standards. The location of people living in the WUI and rural areas is key information for defining potential wildfire impacts to people and homes. Initially provided as raster data, it was converted to a polygon to allow for analysis. The Wildland Urban Interface Risk Index data ranges from 0 to -9 with lower values being most severe (as noted previously, this is only a measure of relative risk). Figure B.17 shows the areas of analysis where any grid cell is less than -5. Areas with a value below -5 were chosen to be displayed as areas of risk because this showed the upper echelon of the scale and the areas at highest risk. Table B.38 shows the results of the analysis. B:59

60 FIGURE B.16: WUI RISK INDEX AREAS IN DESOTO COUNTY Source: Southern Wildfire Risk Assessment Data B:60