CHAMPS ’17:
A Hazard Assessment for Texas
TEXAS GEOGRAPHIC SOCIETY
NOVEMBER 7, 2017
(An HMGP 1791-107 Report)
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TABLE OF CONTENTS
Section 1: CHAMPS ’17 Introduction ...... 1
Section 2: The Texas Hazard Context ...... 3 2.1: Climate ...... 9 2.2: Department of Public Safety Regions ...... 11 2.3: Population ...... 14 2.4: The Built Environment ...... 17 2.5: Exposure Summary ...... 24
Section 3: Weather-Related Hazard Risks ...... 25 Historical Overall Weather-Related Hazards Impacts ...... 26 Future Weather-Related Hazard Risks ...... 34 3.1: Hurricanes, Tropical Storms and Depressions ...... 37 Historical Experience ...... 40 Future Risks ...... 47 3.2: Drought ...... 51 Historical Experience ...... 53 Future Risks ...... 59 3.3: Hailstorms ...... 64 Historical Experience ...... 66 Future Risks ...... 70 3.4: Severe Coastal Flooding ...... 76 Historical Experience ...... 78 Future Risks ...... 83 3.5: Riverine Flooding ...... 88 Historical Experience ...... 91 Future Risks ...... 97 3.6: Tornados ...... 101 Historical Experience ...... 103 Future Risks ...... 109 3.7: Severe Thunderstorm Wind ...... 114 Historical Experience ...... 118 Future Risks ...... 121 3.8: Wildfire ...... 124 Historical Experience ...... 128 Future Risks ...... 131 i CHAMPS ’17: A Hazard Assessment for Texas
TABLE OF CONTENTS (CONTINUED) 3.9: Winter Weather ...... 133 Historical Experience ...... 134 Future Risks ...... 137 3.10: Lightning ...... 139 Historical Experience ...... 141 Future Risks ...... 144 3.11: Extreme Cold ...... 146 Historical Experience ...... 148 Future Risks ...... 151 3.12: Extreme Heat...... 153 Historical Experience ...... 154 Future Risks ...... 158
Section 4: Other Hazard Risks ...... 161 4.1: Coastal Erosion ...... 162 4.2: Inland Erosion ...... 168 4.3: Subsidence ...... 174 4.4: Earthquakes ...... 183
Appendicles
Appendix 1: Weather-Related Hazards Summaries ...... 193 A1.1: Region 1 Weather-Related Hazard Summary ...... 194 A1.2: Region 2 Weather-Related Hazard Summary ...... 197 A1.3: Region 3 Weather-Related Hazard Summary ...... 200 A1.4: Region 4 Weather-Related Hazard Summary ...... 203 A1.5: Region 5 Weather-Related Hazard Summary ...... 206 A1.6: Region 6 Weather-Related Hazard Summary ...... 209
Appendix 2: Weather-Related Hazard Data and Processing ...... 213 A2.1: Weather-Related Hazard Data ...... 213 A2.2: Weather-Related Hazard Forecast Methodology ...... 217 A2.3: Weather Pattern Related Hazard Change Rates ...... 220
ii CHAMPS ’17: A Hazard Assessment for Texas
MAPS GENERATED FOR THIS REPORT Section 2: 2.2.1: Department of Public Safety Regions ...... 11 2.3.1: Texas Estimated Population 2016 ...... 14 2.3.2: Texas Social Vulnerability Index ...... 16
2.4.1: Texas Building Values ...... 17 2.4.2: Region 1 Building Values per Square Mile ...... 18 2.4.3: Region 2 Building Values per Square Mile ...... 19 2.4.4: Region 3 Building Values per Square Mile ...... 20 2.4.5: Region 4 Building Values per Square Mile ...... 21 2.4.6: Region 5 Building Values per Square Mile ...... 22 2.4.7: Region 6 Building Values per Square Mile ...... 23
Section 3: 3.0.1: Percent Weather-Related Hazard Dollar Losses: 1996 - 2016 ...... 30 3.0.2: Total Historical Weather-Related Hazard Dollar Losses ...... 31 3.0.3: Region 2 Weather-Related Hazard Dollar Losses ...... 33 3.0.4: Weather-Related Hazard Dollar Loss Forecast ...... 36
3.1.1: Hurricane/TS/D Wind Risk Zones (100-yr storm) ...... 38 3.1.2: Hurricane TS/D Storm Track Events by County ...... 39 3.1.3: Historical Hurricane TS/D Dollar Losses ...... 44 3.1.4: Historical Hurricane TS/D Dollar Losses in Region 2 ...... 45 3.1.5: Harris County Hurricane TS/D Storm Tracks ...... 46 3.1.6: Hurricanes, TS/D Dollar-Loss Forecast ...... 47
3.2.1: Historical Drought Dollar Losses ...... 57 3.2.2: Historical Drought Dollar Losses in Region 5 ...... 58 3.2.3: Drought Dollar Loss Forecast ...... 59 3.2.4: Forecast Drought Dollar Losses in Region 5 ...... 62
3.3.1: Historical Hailstorm Dollar Losses ...... 69 3.3.2: Historical Hailstorm Dollar Losses in Region 1 ...... 70 3.3.3: Hailstorm Dollar Loss Forecast ...... 71 3.3.4: Forecast Hailstorm Dollar Losses in Region 1 ...... 75
3.4.1: Texas Storm Surge Basins ...... 76 3.4.2: Historical Severe Coastal Flooding Dollar Losses ...... 81 3.4.3: Historical Severe Coastal Flooding Dollar Losses in Region 2 ...... 82 3.4.4: Severe Coastal Flooding Dollar Loss Forecast ...... 83
iii CHAMPS ’17: A Hazard Assessment for Texas
MAPS (CONTINUED)
3.5.1: Historical Riverine Flooding Dollar Losses ...... 95 3.5.2: Historical Riverine Flooding Dollar Losses in Region 6 ...... 96 3.5.3: Riverine Flooding Dollar Loss Forecast ...... 97 3.5.4: Forecast Riverine Flooding Dollar Losses in Region 6 ...... 100
3.6.1: Historical Tornado Dollar Losses ...... 107 3.6.2: Historical Tornado Dollar Losses in Region 1 ...... 108 3.6.3: Tornado Dollar Loss Forecast ...... 109 3.6.4: Forecast Tornado Dollar Losses in Region 1 ...... 113
3.7.1: Historical Severe Thunderstorm Wind Dollar Losses ...... 120 3.7.2: Severe Thunderstorm Wind Dollar Losses Forecast ...... 121 3.7.3: Forecast Severe Thunderstorm Wind Dollar Losses in Region 5 ...... 123
3.8.1: Historical Wildfire Dollar Losses ...... 130 3.8.2: Wildfire Dollar Losses Forecast ...... 131
3.9.1: Historical Winter Weather Dollar Losses ...... 136 3.9.2: Winter Weather Dollar Losses Forecast ...... 137
3.10.1: Historical Lightning Dollar Losses...... 143 3.10.2: Lightning Dollar Losses Forecast ...... 144
3.11.1: Historical Extreme Cold Dollar Losses ...... 150 3.11.2: Extreme Cold Dollar Losses Forecast ...... 151
3.12.1: Historical Extreme Heat Dollar Losses ...... 156 3.12.2: Extreme Heat Dollar Losses Forecast ...... 158 3.12.3: Extreme Heat Deaths and Injuries Forecast ...... 160
A1.1.1: Region 1 Weather-Related Dollar Loss Forecast: 2019 - 2023 ...... 196 A1.2.1: Region 2 Weather-Related Dollar Loss Forecast: 2019 - 2023 ...... 199 A1.3.1: Region 3 Weather-Related Dollar Loss Forecast: 2019 - 2023 ...... 202 A1.4.1: Region 4 Weather-Related Dollar Loss Forecast: 2019 - 2023 ...... 205 A1.5.1: Region 5 Weather-Related Dollar Loss Forecast: 2019 - 2023 ...... 208 A1.6.1: Region 6 Weather-Related Dollar Loss Forecast: 2019 - 2023 ...... 211
iv CHAMPS ’17: A Hazard Assessment for Texas
TABLES GENERATED FOR THIS REPORT
Section 2: 2.3.1: DPS Region Populations Past and Future ...... 15 2.5.1: Summary of Texas Hazard Exposure ...... 24
Section 3: 3.0.1: Average Annual Weather-Related Dollar Losses (1996-2016) ...... 26 3.0.2: Historical Weather-Related Hazard Impacts ...... 27 3.0.3: Annual Dollar Losses from all Weather-Related Hazards ...... 29 3.0.4: Historical Weather-Related Hazard Impacts by Region ...... 32 3.0.5: Weather-Related Hazard Impact Forecasts (2019-23) ...... 34 3.0.6: Weather-Related Impact Forecasts by Region ...... 35
3.1.1: Historical Hurricane TS/D Impacts ...... 40 3.1.2: Historical Named Storms ...... 41 3.1.3: Annual Dollar-Losses from Hurricane TS/Ds ...... 42 3.1.4: Hurricane TS/D Impact Forecast ...... 49
3.2.1: Historical Drought Impacts ...... 53 3.2.2: Annual Dollar-Losses from Drought ...... 54 3.2.3: Drought Impact Forecast ...... 61
3.3.1: Historical Hailstorm Impacts ...... 66 3.3.2: Annual Dollar-Losses from Hailstorms ...... 67 3.3.3: Hailstorms Impact Forecast ...... 74
3.4.1: Historical Severe Coastal Flooding Impacts ...... 78 3.4.2: Annual Dollar-Losses from Severe Coastal Flooding ...... 79 3.4.3: Severe Coastal Flooding Impact Forecast...... 86
3.5.1: Historical Riverine Flooding Impacts ...... 91 3.5.2: Annual Dollar-Losses from Riverine Flooding ...... 92 3.5.3: Riverine Flooding Impact Forecasts ...... 99
3.6.1: Historical Tornado Impacts ...... 103 3.6.2: Annual Dollar-Losses from Tornados ...... 104 3.6.3: Tornado Impact Forecasts ...... 112
3.7.1: Historical Severe Thunderstorm Wind Impacts ...... 118 3.7.2: Annual Dollar-Losses from Severe Thunderstorm Wind ...... 119 3.7.3: Severe Thunderstorm Wind Impact Forecasts ...... 122
v CHAMPS ’17: A Hazard Assessment for Texas
TABLES (CONTINUED)
3.8.1: Historical Wildfire Impacts ...... 128 3.8.2: Annual Dollar-Losses from Wildfire ...... 129 3.8.3: Wildfire Impact Forecasts ...... 132
3.9.1: Historical Winter Weather Impacts ...... 134 3.9.2: Annual Dollar-Losses from Winter Weather ...... 135 3.9.3: Winter Weather Impact Forecasts ...... 138
3.10.1: Historical Lightning Impacts ...... 141 3.10.2: Annual Dollar-Losses from Lightning ...... 142 3.10.3: Lightning Impact Forecasts ...... 145
3.11.1: Historical Extreme Cold Impacts ...... 148 3.11.2: Annual Dollar-Losses from Extreme Cold ...... 149 3.11.3: Extreme Cold Impact Forecasts ...... 152
3.12.1: Historical Extreme Heat Impacts ...... 154 3.12.2: Annual Dollar-Losses from Extreme Heat ...... 155 3.12.3: Extreme Heat Impact Forecasts ...... 159
A1.1.1: Region 1 Weather-Related Hazard Impacts: 1996 - 2016 ...... 194 A1.1.2: Region 1 Weather-Related Impact Forecast: 2019 - 2023 ...... 195
A1.2.1: Region 2 Weather-Related Hazard Impacts: 1996 - 2016 ...... 197 A1.2.2: Region 2 Weather-Related Impact Forecast: 2019 - 2023 ...... 198
A1.3.1: Region 3 Weather-Related Hazard Impacts: 1996 - 2016 ...... 200 A1.3.2: Region 3 Weather-Related Impact Forecast: 2019 - 2023 ...... 201
A1.4.1: Region 4 Weather-Related Hazard Impacts: 1996 - 2016 ...... 203 A1.4.2: Region 4 Weather-Related Impact Forecast: 2019 - 2023 ...... 204
A1.5.1: Region 5 Weather-Related Hazard Impacts: 1996 - 2016 ...... 206 A1.5.2: Region 5 Weather-Related Impact Forecast: 2019 - 2023 ...... 207
A1.6.1: Region 6 Weather-Related Hazard Impacts: 1996 - 2016 ...... 209 A1.6.2: Region 6 Weather-Related Impact Forecast: 2019 - 2023 ...... 210
A2.2.1: Texas Weather-Related Hazard Risk Forecast Model ...... 218 A2.2.2: Weather Hazard Risk Change Factors ...... 219
vi CHAMPS ’17: A Hazard Assessment for Texas
Section 1: CHAMPS ’17 Introduction
The Federal Emergency Management Administration (FEMA) is the lead agency in the nation for coordinating government planning, mitigation and response to hazards. In Texas they work through the Texas Division of Emergency Management (TDEM), a division of the Texas Department of Public Safety. The Texas Geographic Society (TXGS) has been working with TDEM to help support hazard mitigation planning in Texas since 2002.
The Stafford Act is the federal law that provides federal funding for disaster recovery assistance in the United States. To ensure that disaster assistance dollars are spent not just on remediating damage, but also on helping reduce future damages and other impacts from hazards, part of the Stafford Act, allows funds to be spent on hazard mitigation projects that are expected to reduce future dollar- losses or loss of life and injury. To be eligible to receive federal funds for hazard mitigation projects, communities and the states they are in, must have demonstrated that they have anticipated these needs by having current and approved Hazard Mitigation Plans.
Hazard Mitigation Plans must include discussions of relevant natural hazards and identification of strategies and actions to address those hazards. In discussing hazards these plans must include discussions of underlying hazard exposure (geography, population and the built environments), identification and analysis of the nature of the hazards that present risks to those communities, analysis of historical impacts and assessment of future risks related to those hazards. Local and state governments are required to revise their mitigation plans every 5 years.
In 2013, with the support from FEMA and TDEM (through the Hazard Mitigation Grant Program – HMGP), TXGS published the first Community Hazard Analysis and Mitigation Planning Support Reports (CHAMPS ’13). These were released in 254 volumes: one for each county in Texas. The objective of these reports was to provide hazard analysis that local communities could use in developing their required hazard mitigation plans. Specifically CHAMPS ‘13 provided local mitigation planners with information describing the historical patterns and future likelihoods of various types of hazards in the counties their communities were in. This information was, and continues to be, used by many local mitigation planners in developing the hazard assessment portions of their hazard mitigation plans.
After delivery of CHAMPS ’13, TDEM representative sought follow-on activities from TXGS in the development of updated CHAMPS reports and the development of a statewide version to support the state hazard assessment process. This, the CHAMPS ’17 Report is the first product of those follow-on efforts.
1 CHAMPS ’17: A Hazard Assessment for Texas
Through work with TDEM and the State Hazard Mitigation Team, it was decided that CHAMPS ’17 would focus at the state level and take a more comprehensive approach than was taken in the CHAMPS ’13 Reports. Specifically, that CHAMPS ’17 would seek not only to analyze historical patterns of natural hazards in Texas, but would assess future risks and thereby contribute more substantially to the process of revising the State Hazard Mitigation Plan. For this reason, CHAMPS ’17 has been developed as a state hazard assessment. It is intended to meet as many FEMA requirements for a state assessment as possible, given time, budget and other resources. There is one exception to this: TDEM and FEMA agreed during the writing of this document to address the vulnerability of state assets (S5 of the Standard State Mitigation Plan Regulation Checklist) in a manner that is outside the scope of this report.
In the early summer of 2018, CHAMPS ‘18 will be released, it will be provided in 255 volumes (254 county reports and one state report). Those reports will be developed to extend the benefits of this new, more inclusive approach to counties. It is also anticipated that CHAMPS ’18 will include information on the mitigation priorities established by the state through this revision of its mitigation plan. The objective will be to promote common understanding of natural hazards and aligned strategies to deal with those hazards and thereby improve mitigation in Texas and help save lives and money.
Use of this Report
The materials that follow are intended to be used in whole or in part by state or local mitigation planners in development of their mitigation plans or plan updates. Also, anyone seeking to understand the mix and severity of hazard risks in Texas should find some value in this material.
This remainder of this report is includes: Section 2: The Texas Hazard Context Section 3: Weather-Related Hazard Risks Section 4: Other Hazard Risks Appendix 1: Weather-Related Hazard Summaries by DPS Region Appendix 2: Weather-Related Hazard Data and Processing
This report is distributed free-of-change to interested parties. It is being distributed in Microsoft Word format to allow recipients to extract whatever maps, tables or narratives they wish to insert their own documents or presentations. Citations and testimonials regarding use are appreciated. For questions or other communications please email: [email protected].
2 CHAMPS ’17: A Hazard Assessment for Texas
Section 2: The Texas Hazard Context
Texas is the second largest state in the United States, the largest of the 48 contiguous states and larger than the 15 smallest states combined. The 2010 census showed Texas with a population of just over 25 million; the second most populous state. At that time, Texas had more people than the 17 least populated states combined. The estimated population of Texas in 2016 was 27.7 million placing its growth since 2010 at just under 500-thousand a year. Texas touches five other US states including New Mexico, Colorado, Oklahoma, Arkansas and Louisiana. It has a 1,254 mile-long international border with Mexico.
At over 267,000 square miles, Texas is more than seven percent of the United States. The longest straight-line distance in Texas is 802 miles in a general north- south direction from the northwest corner of the Panhandle to the southern-most point on the Rio Grande below Brownsville. The longest east-west distance is 773 miles from the eastward bend in the Sabine River in Newton County to the western bulge of the Rio Grande just above El Paso.
3 CHAMPS ’17: A Hazard Assessment for Texas
Texas has high arid plains in its panhandle, rolling hills through its central portions and vast coastal plains along the Gulf of Mexico. In southwest Texas there are mountains and deserts and in deep-east Texas there are tens of thousands of square miles of piney woods. The highest point in Texas is Guadalupe Peak at 8,749 feet above mean sea level (MSL). Guadalupe and its twin, El Capitan (8,085 feet) near the New Mexico border. The Caprork Escarpment, a plateau elevated at 2,600 to 4,300 feet above MSL extends across West Texas (see figure). East of the Caprork Escarpment the land surface slopes downward to sea level along the Gulf Coast.
Geologically, most of Texas was built- up over eons from the gradual deposition of silt, clay and sea creatures that settled on the bottom of a vast prehistoric sea. Over time, these deposits compressed into limestone and sandstone that make up the majority of the surface rock. This map shows rocks of various geologic ages visible on the surface of Texas today.
4 CHAMPS ’17: A Hazard Assessment for Texas
The sedimentary rocks in Texas fostered a surface environment where karst features link surface water to ground- water, where there the aquifers are many-layered and springs are plentiful. This map shows the major aquifers in Texas. There are too many lesser aquifers to show on one map.
Mountains, plateaus, hills, plains, beaches, river valleys, and canyon lands make Texas one of the most physically diverse in the nation. Texas has 12 distinct ecoregions as depicted here:
1. Piney Woods 2. Oak Woods & Prairies 3. Blackland Prairies 4. Gulf Coast Prairies & Marshes 5. Coastal Sand Plains 6. South Texas Brush Country 7. Edwards Plateau 8. Llano Uplift 9. Rolling Plains 10. High Plains 11. Trans Pecos
5 CHAMPS ’17: A Hazard Assessment for Texas
River Basins of Texas Texas is drained by 15 major river basins within the state and eight coastal basins. These played important roles during the early development of Texas and remain important to the state’s economy today. The upper reaches of most of these river systems have been impounded by dams to reduce flooding downstream, to provide water for drinking, industry, and agriculture and in some cases, to provide hydroelectric power. Many of the lower river reaches remain navigable and support important commercial transportation and environmental systems by way of a networks of bays, sounds, estuaries and canals including the Gulf Intracoastal Waterway.
Each of the river basins have several unique features, both climatic (such as precipitation and evaporation) and physiographic (geology, slope, soil type, vegetation and land use practices) that contribute to the nature of runoff from these basins. The map below shows the major river drainage basins with the names of the rivers that drain them and the Coastal drainage basins with their names.
Major River and Coastal Basins of Texas
6 CHAMPS ’17: A Hazard Assessment for Texas
Texas Gulf Coast Texas has 367 miles of open Gulf shoreline, of which 293 miles are open for public use. The coastline runs from just west of the mouth of the Sabine River in the most southeastern part of the state to Boca Chico, near the mouth of the Rio Grande River in the most southern part of the state. The Texas Gulf Coast consists of a system of barrier islands and peninsulas, which provides protection for numerous bays and inlets from oncoming waves. These features are relatively young and most are less than 7,000 years in age.
Up and down the Texas Gulf Coast there are a variety of coastal dune environments, each with its unique geomorphology and coastal processes. In areas along the upper coast, from Sabine Pass to the Freeport Ship Channel, coastal dunes are relatively small in comparison to other parts of the coast. This area is characteristically a sediment starved system. Along the middle coast, commonly referred to as the Coastal Bend, coastal dunes form an extensive and stable dune complex with fore-dune ridge approximately 26 to 40 feet high.
Barrier islands are generally elongated, exposed narrow accumulations of sediment, usually sand, in the shallow coastal zone and are separated from the mainland by some combination of coastal bays and marshes. Texas has 17 barrier islands that total 191,762 acres. These islands are vital natural habitats and nesting areas for wading birds and sea birds, and a resting area for migratory birds. Barrier island fore-dunes are critical nesting sites for the endangered Kemps Ridley sea turtle.
7 CHAMPS ’17: A Hazard Assessment for Texas
Barrier islands also provide a level of protection for the mainland against storm impacts. The first apparent feature landward of the beach along the Texas Gulf Coast, coastal dunes from Sabine Pass to the mouth of the Rio Grande vary in natural position, contour, volume, elevation, and vegetative cover. These variations are a direct result of natural processes, which include prevailing wind currents, sediment budget, climate, and biota. These variations influence dune formation.
Coastal dunes are a dynamic component of the barrier islands that are in a constant state of change and part of a natural cycle that ensures the health of beaches, marshes, and wetlands along the Gulf and bay shoreline. Barrier islands tend to have high-energy environments on the Gulf side and low-energy environments on the bay side.
Barrier Islands are also home to many vibrant communities, tourist spots and travel destinations. Galveston Island is a barrier island on which a significant and historic Texas city sits. After the great hurricane of 1900, in which 6 to 8 thousand people were killed, a seawall was constructed to help protect that city of Galveston from storm surge. The picture to the left shows from above, the Galveston Seawall and the intensive development behind it.
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2.1: CLIMATE
Texas’ climate is as varied as its landscape. Its variability results from the interactions between Texas’ geographic location and the movements of seasonal air masses, including arctic fronts, the jet stream, subtropical west winds, tropical storms, and a subtropical high pressure system known as the Bermuda High.
The range between summer and winter average monthly temperatures increases relative to distance from the Gulf of Mexico. In addition, the variability of both daily temperature and precipitation totals increase inland across the state and away from the Gulf of Mexico.
The Gulf Coast sees more pronounced rainy seasons in the fall and spring. These two rainy seasons are affected by polar fronts interacting with moist Gulf air during those seasons. The fall season also includes precipitation associated with tropical cyclones or systems approaching or entering the state from the Gulf of Mexico. These tropical disturbances will often move in and stall out over Central and North Texas, dumping large amounts of rain and causing flooding.
9 CHAMPS ’17: A Hazard Assessment for Texas
Temperature Average annual maximum daily temperatures gradually increases from less than 70˚F in the northern Panhandle to more than 82˚F in the lower Rio Grande Valley, except for isolated mountainous areas of Far West Texas where the average annual maximum daily temperature sharply increases from less than 72˚F in the Davis and Guadalupe mountains to more than 80˚F in the Presidio and Big Bend areas.
The average date of the first freeze in the fall is November 1, in the Panhandle and December 16, along the Lower Texas Coast. The average date of the last freeze in the spring is January 30, in the south and April 15, in the Northwest.
Average Annual Max. Daily Temperature Average Annual Precipitation
Precipitation Average annual precipitation decreases from over 55 inches in Beaumont to less than 10 inches in El Paso. Except for the wetter, eastern portion of the state, evaporation exceeds precipitation for most of Texas, yielding a semi-arid climate that becomes arid in Far West Texas. Relative humidity varies throughout the state, depending on rainfall and evaporation rates, but generally decreases from east to west.
Most of the state’s precipitation occurs in rainfall. Small amounts of ice and snow become increasingly probable toward the north and west. Annual snowfall ranges from no snow to a record 65 inches in 1923-1924, at Romero, near the border of New Mexico. The heaviest recorded snowfall in a 24-hour period was 2 inches at Plainview in February 1956. The greatest monthly accumulation was 36 inches at Hale Center in February 1956.
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2.2: DEPARTMENT OF PUBLIC SAFETY REGIONS
There are 254 counties in Texas (roughly 12 % of the nation’s counties). The smallest county is Rockwall County (148.6 square miles) and the largest is Brewster County (6,193.1 square miles - roughly the same size as Hawaii). In 2009, the Texas Department of Public Safety (DPS) reorganized and strengthened its regional structure by creating seven DPS Regions and new positions of Regional Commander, for each region. Region 7 is an administrative designation for the capital complex – entirely within Region 6. Regions 1 -6 are used in this analysis to identify and describe variations in populations, built environments and hazard distributions across the state. They each have distinctive geographies, population distributions and hazard profiles. These regions are shown below. The inset table lists their areas in square miles.
Map 2.2.1: Department of Public Safety Regions
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DPS Region Descriptions Individual DPS Regions are described below. The following graphic show locations of the major cities mentioned in these descriptions.
Region 1 contains the Dallas/Fort-Worth Metroplex. It runs from the Piney Woods of east Texas to the High Plains of northwest Texas. It has 42 counties, covers 31,400 square miles and constitutes 11.8% of the state. Regions 1 and two are the smallest regions by area but Region 1 is slightly bigger than Region 2. They are both approximately the same size as South Carolina. With an estimated 2016 population of 8,625,547, Region 1 has the highest population. If it were a state, it would be the 12th most populous in the country, with fewer people than New Jersey but more than Virginia.
Region 2 largest cities are the Houston/Galveston Metroplex and Beaumont. Its coastal regions run from Louisiana to the mid Gulf Coast. Region 2 has 35 counties, covers 31,005 square miles and constitutes 11.6% of the state. It is the smallest region. Region 2’s estimated 2016 population of 8,027,607 make it the second most populous region. If it were a state, it 12 CHAMPS ’17: A Hazard Assessment for Texas
would be the 12th most populous in the country, with fewer people than New Jersey but more than Virginia.
Region 3 largest cities are Corpus Christ, Laredo, McAllen and Brownsville. Its coast runs from the mid- Gulf Coast to Mexico. The international boarder it shares with Mexico runs roughly 600 miles from the mouth of the Rio Grande River, halfway to New Mexico. Region 3 has 27 counties, covers 36,070 square miles and constitutes 13.5% of the state. The Rio Grande Valley makes Region 3 more agricultural than regions 1, 2 and 6: it is less agricultural than regions 4 and 5. Region 3’s estimated 2016 population of 2,421,457 makes it the fourth most populated region. If it were a state, it would be the 36th most populous in the country, with fewer people than Nevada but more than New Mexico.
Region 4 largest cities are El Paso, Midland, Odessa and San Angelo; it shares an equally long international border with Mexico as Region 3. Region 4 extends northward from the mountains of Big Bend to the High plains of Northwest Texas. It has 36 counties, covers 61,292 square miles and constitutes 23% of the state. Regions 4 and 5 are the largest regions in the state. Together they make up 48% of the state of Texas. Region 4’s estimated 2016 population 1,511,557 makes it the fifth most populous region. If it were a state, it would be the 40th most populous in the country, with fewer people than Idaho but more than Hawaii.
Region 5 is the largest region. Its largest cities are Amarillo, Lubbock and Abilene. Its area includes the Texas panhandle and the most of the High Plains. It is highly agricultural. Region 5 has 71 counties, covers 66,967 square miles and constitutes 25.1% of the state. Region 5 is the largest region in the state. It is slightly larger than the state of Florida. Region 5’s estimated 2016 population 1,429,523 make it the least populated region. If it were a state, it would be the 40th most populous in the country, with fewer people than Idaho but more than Hawaii.
Region 6 contains San Antonio, Austin and Waco. On its west side, Region 6 covers much of the Texas Hill Country and the Edwards Escarpment. Its mid- section includes the IH-35 corridor from south of San Antonio almost to Dallas. To the east, it has a long stretch of coastal black-lands then one county on the Gulf Coast. Region 6 has 43 counties, covers 39,756 square miles and constitutes 14.9% of the state. Region 6 is slightly larger than the state of Kentucky. With an estimated 2016 population of 5,709,501 Region 6 is the third most populous region. If it were a state, it would be the 20th most populous in the country, with fewer people than Maryland but more than Wisconsin.
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2.3: POPULATION
2016 estimates place the total Texas population at 27.7 million. Six of the largest 20 cities in the United States are in Texas, including Houston (4th at 2.3 million), San Antonio (7th at 1.5 million), Dallas (9th at 1.3 million), Austin (11th at 948 thousand), Fort Worth (16th at 854 thousand), and El Paso (20th at 683 thousand).
Map 2.3.1 displays Texas county populations in 2016. Counties are colored to show their populations relative to other counties in the state. Each color represents approximately 20 % of the counties statewide. With 254 counties in Texas, there are about fifty counties in each color. The inset table lists the total estimated populations for DPS regions in order of their totals. Regions are outlined and labeled on the map. Harris County is the most populous in Texas. With an estimated 2016 population of over 4.5 million it was 57% of Region 2 and 16% of the state. Harris County’s population was 85% of regions 3, 4 and 5 combined.
Map 2.3.1: Texas Estimated Population in 2016
14 CHAMPS ’17: A Hazard Assessment for Texas
Table 2.3.1 shows regional population figures for January 1st, 2010, 2016 (shown in the map above) and 2024 (as forecast in this study). This table shows the population growth that Texas is currently undergoing. It also shows the shifting shares of the population between regions. Though it continues to be the largest, Region 1 loses a couple of decimal points off its percentage over time. Regions 2 and 6 grow at the most rapid pace: each gaining a percent in their share of statewide population over 14 years. Regions 3, 4 and 5, are growing less rapidly than less than the rest of the state. As the lower part of the table shows, more populated regions are growing almost twice as fast at the less populated ones.
Table 2.3.1: DPS Region Populations Past and Future 14-year 2010 Census 2016 Estimate 2024 Forecast % Growth Region 1 7,844,875 8,625,547 9,827,579 25% Region 2 7,173,802 8,027,607 9,367,616 31% Region 3 2,272,003 2,421,457 2,640,570 16% Region 4 1,397,784 1,511,557 1,686,015 21% Region 5 1,389,836 1,429,523 1,488,783 7% Region 6 5,067,261 5,709,501 6,719,781 33% Total 25,145,561 27,725,192 31,730,345 26%
% in 2010 % in 2016 % in 2024 Region 1 31.2% 31.1% 31.0% Region 2 28.5% 29.0% 29.5% Region 3 9.0% 8.7% 8.3% Region 4 5.6% 5.5% 5.3% Region 5 5.5% 5.2% 4.7% Region 6 20.2% 20.6% 21.2% Total 100% 100% 100%
More Populated Regions (1, 2 & 6) 14-year 2010 Census 2016 Estimate 2024 Forecast % Growth Total 20,085,938 22,362,655 25,914,976 29% % of State 79.9% 80.7% 81.7%
Less Populated Regions (3,4 & 5) 14-year 2010 Census 2016 Estimate 2024 Forecast % Growth Total 5,059,623 5,362,537 5,815,368 15% % of State 20.1% 19.3% 18.3%
Methodologies used for this population forecast are discussed in Appendix 2.
15 CHAMPS ’17: A Hazard Assessment for Texas
Social Vulnerability
Map 2.3.2 shows social vulnerability index (SVI) for Texas counties. SVI is an important metric when evaluating hazard vulnerabilities. It reflects the ability of communities to respond and recover from disasters. Social vulnerability tends to increase as populations are poorer and more rural. The map below is almost the reverse of the population map shown above. For instance, the green areas on this map - reflecting low social vulnerability are the same areas shown in red in the population map above (especially for Regions 1, 2 and 6).
It is important for hazard mitigation and response planners to understand where the most at-risk populations are.
Map 2.3.2: Texas Social Vulnerability Index
16 CHAMPS ’17: A Hazard Assessment for Texas
2.4: THE BUILT ENVIRONMENT
Map 2.4.1 shows the total value of buildings in each Texas County as estimated in FEMA’s HAZUS-MH ver3.2 released in October 2016 (building contents and infrastructure values are not included). According to this source, 50 of the lowest building-value counties in Texas have less than $560 million dollars’ worth of buildings and Harris County has 800 times that.
Red on this map indicates the 50 most at-risk counties in terms of property dollar loss exposure (or built environment value). $6 billion worth of built environment is what it takes for a county to be shown here in red. At $448 billion worth of built environment, Harris County leads the state. It has 58 % of the built environment in Region 2 and more total built environment value than regions 3, 4 and 5 combined. The regional maps that follow present county building values by square mile by region.
Map 2.4.1: Texas Building Values
17 CHAMPS ’17: A Hazard Assessment for Texas
Maps 2.4.2 through 2.4.7 show county building values per square mile for all DPS regions. These maps compare counties within regions by building value density. The point of looking at building value density is to distinguish concentrations of exposed infrastructure. Each color in these depictions, represents approximately 20 % of the counties in that region.
Region 1 has 42 counties, so each color is approximately eight counties. Dallas County, in Region 1, has the highest building values per square mile in the state (at $298 million per square mile). Rockwall County would not be in the top bracket if total building values were being mapped, but it shows-up here because the density of development in Rockwall puts it in the first tier of a building value density map. The table in the lower left shows the counties with the highest building values per square mile and reports those values. It is interesting to compare these county- level dollars per square mile values among the regions on the following maps. Note, all the values on these maps are in thousands.
Map 2.4.2: Region 1 Building Values per Square Mile
18 CHAMPS ’17: A Hazard Assessment for Texas
Map 2.4.3 shows the same level information for Region 2. Region 2 has 36 counties, so each color is approximately seven counties. Harris County, in Region 2, is the highest statewide in terms of total building value, but based on density of development, it is second highest (at $252 million per square mile) to Dallas County (at $298 million). Harris County is almost twice as big as Dallas County however. The total value of the buildings in Harris County is almost $448 billion while total value of the buildings in Dallas County is $271 billion.
Harris County has almost three time the building value density (the density of exposure) as the next most densely developed county, Fort Bend. Note, all the values on these maps are in thousands.
Map 2.4.3: Region 2 Building Values per Square Mile
19 CHAMPS ’17: A Hazard Assessment for Texas
Map 2.4.4 shows the same level information for Region 3. Region 3 has twenty- seven counties, so each color is approximately five counties. Nueces County has the highest building values per square mile of any county in Region 3 (at $29.5 million per square mile), it is less than any of the top 5 individual counties in regions 1 or 2.
Map 2.4.4: Region 3 Building Values per Square Mile
All the values on these maps are in thousands.
20 CHAMPS ’17: A Hazard Assessment for Texas
Map 2.4.5 shows the same level information for Region 4. Region 4 has thirty-six counties, so each color is approximately seven counties. El Paso County has the highest building values per square mile of any county in Region 4: $59.5 million. The next highest county, Midland has approximately a third of that number $20.7 million.
Map 2.4.5: Region 4 Building Values per Square Mile
All the values on these maps are in thousands.
21 CHAMPS ’17: A Hazard Assessment for Texas
Map 2.4.6 shows the same level information for Region 5. Region 5 has seventy- one counties, so each color is approximately fourteen counties. At $31.7 million dollars per square mile, the building value density in Lubbock is 36% greater that of the next highest county, Wichita County. Lubbock would be the fifth most densely developed county in Region 2 if it were there, but would not make it into the top 5 of Region 1.
Map 2.4.6: Region 5 Building Values per Square Mile
All the values on these maps are in thousands.
22 CHAMPS ’17: A Hazard Assessment for Texas
Map 2.4.7 shows the same level information for Region 6. Region 6 has forty-three counties, so each color is eight or nine counties. The inset table shows that Bexar and Travis Counties both average over a hundred million dollars in building values per square mile. This places these counties 4th and 5th among the most densely developed counties in the state. In a statewide comparison, they would rank behind Dallas (1st), Harris (2nd) and Tarrent (3rd) counties. The highest density development in Region 6 is along the Interstate 35 corridor running from the City of Waco in McLennan County to the City of San Antonio, in Bexar County. Looking back at Map 2.3.1 (on page 14) it is apparent that these are also the highest populated counties in Region 6.
Map 2.4.7: Region 6 Building Values
All the values on these maps are in thousands.
23 CHAMPS ’17: A Hazard Assessment for Texas
2.5: EXPOSURE SUMMARY
Table 2.5.1 presents summarized information on Texas area, population and built environments. Taken together these describe the Texas Hazard exposure. Table 2.5.1: Summary of Texas Hazard Exposure
Area Population Pop. per Bldg. Value (sq. miles) (2016 est.) Building Values sq. mile per sq. mile Region 1 31,400 8,625,547 868,323,770,000 275 27,653,623 Region 2 31,005 8,027,607 769,887,853,000 259 24,831,087 Region 3 36,070 2,421,457 160,906,407,000 67 4,460,948 Region 4 61,292 1,511,557 124,199,951,000 25 2,026,365 Region 5 66,967 1,429,523 145,505,920,000 21 2,172,800 Region 6 39,756 5,709,501 528,376,792,000 144 13,290,492 Statewide 266,490 27,725,192 2,597,200,693,000 104 9,745,959
Area Population Bldg. Values (percent) (percent) (percent) Region 1 11.8% 31.1% 33.4% Region 2 11.6% 29.0% 29.6% Region 3 13.5% 8.7% 6.2% Region 4 23.0% 5.5% 4.8% Region 5 25.1% 5.2% 5.6% Region 6 14.9% 20.6% 20.3% Statewide 100% 100% 100%
The table shows that regions 4 and 5 are the largest, they have the lowest populations, and that regions 1 and 2 are the smallest but have the highest populations. Region 1 shows the highest population and building values density. At $27.6 million per square mile, Region 1 is almost 3 times the statewide average of $9.7 million. Region 3 population density is 3 times that of Region 5 and half of Region 6’s. Region 6’s population density, of 144 persons per square mile, is a little more than half of Region 1’s population density. Regions 1, 2 and 6 are more densely populated and developed and generally have more exposure to hazards to than do the other regions. The exception being Drought. Drought’s biggest dollar impact is in the crop damage it creates. Lower density areas, where farming is prevalent and precipitation is not, have more exposure to this hazard. Region 5 in the Texas panhandle has those characteristics and the vast majority of drought losses in Texas occur there.
24 CHAMPS ’17: A Hazard Assessment for Texas
Section 3: Weather-Related Hazards Risks
The following weather-related hazards are discussed in subsections as indicated: 3.1 Hurricanes Tropical Storms and Depressions; 3.2 Drought; 3.3 Hailstorms; 3.4 Severe Coastal Flooding; 3.5 Riverine Flooding; 3.6 Tornados; 3.7 Severe Thunderstorm Winds; 3.8 Wildfire; 3.9 Winter Weather; 3.10 Lightning; 3.11 Extreme Cold; and 3.12 Extreme Heat
This order was determined based on the magnitude of the financial losses they caused in Texas over the period of January 1, 1996 to December 31st, 2016, as reported in the National Oceanic and Atmospheric Administration (NOAA) Storm Events database for Texas.
Each subsection includes discussion of the nature of the hazards, their historical impacts, their forecasted future impacts and risks. Appendix 1 provides regional summaries that include tables and maps that report historical and forecasted weather-related hazard impacts by DPS Region and for the state as a whole.
The forecasts used here are for the five-year period addressed by this update to the Texas Mitigation Plan: January 1, 2019 to December 31, 2023. These include accommodations for expected population/land use and weather pattern changes. The methodology used in the forecast is described in detail in Appendix 2 Section 3: Weather-Related Hazard Forecast Methodology. Where appropriate, forecasts are followed by presentations of more generalized risk associated with each hazard.
Before proceeding to the hazard-by-hazard discussions, an overview of all weather- related hazard impacts is presented below. This includes a review of historical impacts over the base period (1996-2016) and a summary of forecasted future impacts over the forecast period (2019-2023).
25 CHAMPS ’17: A Hazard Assessment for Texas
Historical Overall Weather-Related Hazards Impacts
This assessment relies on the Storm Events Database from the National Oceanic and Atmospheric Administration (NOAA) as made available through the National Centers for Environmental Information (NCEI). This authoritative database covers all weather-related hazard events reported in Texas over the 21 year base period between January 1, 1996 and December 31, 2016.
The weather-related hazards analyzed here are listed below beside the average annual average dollar losses (property plus crop losses) reported over the base period in the NCEI Storm Events Database.
Table 3.0.1: Average Annual Weather-Related Dollar Losses (1996-2016)
Avg. Annual Dollar Losses Hazard Name $863,804,789 Severe Coastal Flood ** $833,963,572 Hurricanes Tropical Storms and Depressions $724,702,614 Drought $496,043,313 Hailstorms $246,886,387 Flooding $108,896,168 Tornados $ 73,447,456 Wildfire ** $ 70,108,536 Severe Thunderstorm Winds $ 24,504,776 Winter Weather $ 3,234,744 Lightning $ 761,510 Extreme Cold $ 39,276 Extreme Heat ** 12-year averages (instead of 21-year used in the rest of the table).
The higher a Hazard is on this list, the greater the annual dollar losses it causes. The first six hazards each caused losses greater than $100 million dollars a year over the base period. In the individual hazard description sections below, hazards that have caused greater losses are described in greater detail than others.
It is important to note that future occurrences of these hazards are not just probable, in a state the size of Texas, they are certain. The question for this risk assessment is not whether these hazards will cause future impacts, it is how much damage should be expected and where is that damage likely to occur.
26 CHAMPS ’17: A Hazard Assessment for Texas
Table 3.0.2 shows weather-related hazard impacts reported in the NCEI Storm Events Database for Texas over the base period (1996 – 2016). These are listed in order of the total dollar losses (property plus crop losses) reported. Individual hazards are discussed in sections 3.1 – 3.12 below in this same order.
Table 3.0.2: Historical Weather Related Hazard Impacts
Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries HURRICANE TS/D 17,506,951,656 6,283,362 56 2,435 DROUGHT 1,400,610,801 13,818,144,105 5 32 HAIL 9,717,032,805 699,876,770 5 140 S. COASTAL FLOOD 10,365,657,465 13 FLOODING 4,203,291,505 981,322,641 354 6,984 TORNADO 2,189,735,158 97,084,372 84 1,491 S. T-STORM-WIND 1,343,349,529 128,929,747 48 433 WILDFIRE 685,038,019 196,355,458 31 170 WINTER WEATHER 496,986,037 17,614,279 138 1,486 LIGHTNING 67,928,501 1,131 57 252 COLD 13,563,095 2,428,624 19 6 HEAT 268,604 556,200 346 941 Total 47,990,413,175 15,948,596,689 1,156 14,370
% of Prop. % of % of Losses % of Crop Losses Deaths Injuries HURRICANE TS/D 36% 0% 5% 17% DROUGHT 3% 87% 0% 0% HAIL 20% 4% 0% 1% S. COASTAL FLOOD 22% 1% R. FLOODING 9% 6% 31% 49% TORNADO 5% 1% 7% 10% S. T-STORM-WIND 3% 1% 4% 3% WILDFIRE 1% 1% 3% 1% WINTER WEATHER 1% 0% 12% 10% LIGHTNING 0% 0% 5% 2% COLD 0% 0% 2% 0% HEAT 0% 0% 30% 7% Total 100% 100% 100% 100%
Percents for each column illustrate the distribution of impacts between hazards. For example, Hurricanes caused 36% of the property damage over the base period and together with Severe Coastal Flooding these caused 58% of the weather- related property damage statewide. Drought caused 87% of crop damages from all weather-related hazards and Flooding caused 31% of all deaths. 0% in this table means that the impact for that hazard was less than 1-half of 1 percent of the total. Blanks indicates no data in that category.
27 CHAMPS ’17: A Hazard Assessment for Texas
The total dollar losses over the base period are about $64 billion. This puts the average annual state losses at about $3 billion a year. The top 4 of hazards have each produced more than 10 billion dollars in damages over the 21-year period. The next 3 have each produced more than a billion dollars of damages. Wildfire and Winter Weather have each produced between 500 million and 1-billion dollars of damage. And, while the last three hazards have each produced less than $100 million of damages they are none the less significant hazards.
Riverine Flooding killed more than any other hazard over the base period: 354 people (16.9 a year). Extreme Heat was the second highest cause of death: it killed 346 (16.5 a year). Winter Weather, Tornados and Lightning are 3rd, 4th and 5th with regard to the number of deaths they caused. Although Hurricane TS/Ds were the most expensive with regard to property dollar losses they are 6th in terms of the number of deaths it caused.
Landslide event reports are collected in the NCEI storm events database under the more technical term, Debris Flow. There were two events of Debris Flow recorded for Texas over the base period. Neither of these had any associated impacts. For this reason Debris Flow (or Landslides) are not included in this analysis. Other hazard types collected by NCEI, but excluded from this analysis because there were no impacts included: Dense Fog Rip Current Astronomical Low Tide Dense Smoke Freezing Fog Funnel Cloud High Surf Dust Devil
Expansive Soils is a hazard category that was analyzed in the last state Mitigation Plan. The damage that expansive soils cause is related to their ability to contract during times of drought. Contracting soils leave building foundations with inadequate support and can cause concrete slabs to crack. Damage related to expansive soils is therefore addressed in the drought section below.
Dam and Levee Failure is also sometimes treated as a separate hazard category - it was analyzed separately in the last state Mitigation Plan. The damage done by dam or levee failure is flood damage. Dam and levee failure issues are therefore addressed in the flood section below.
Table 3.0.3, shows dollar losses (property plus crop losses) for all weather-related hazards by year over the base period for each region and for the state. At the bottom is a calculation of the average annual dollar losses for each area over this period. The nine years with higher than average losses are highlighted on this table. The two with the highest losses (2001 and 2008) are years when one or more hurricanes hit Texas, mostly in Region 2. The other 7 (1998, 2005, 2006, 2011, 2012, 2013 and 2016) had more distributed losses. A significant portion of which occurred in Region 5 and came in the form of crop losses due to drought.
28 CHAMPS ’17: A Hazard Assessment for Texas
100%
378,650,454
951,514,569
660,787,495
392,367,336
692,840,261
412,859,307
638,774,940
651,137,622
Totals
3,611,894,800
2,626,107,949
1,164,048,943
3,760,711,379
3,663,459,404
3,172,221,831
3,572,727,056
4,095,122,939
8,224,299,868
1,503,576,450
3,623,845,841
1,707,565,491
18,434,495,929
3,044,714,755
63,939,009,864
8%
2,568,522
3,858,297
6,944,090
31,824,609
62,889,040
12,150,599
43,402,865
26,978,723
22,004,199
278,246,452
111,316,842
308,706,895
202,632,397
204,532,777
161,580,537
124,292,285
257,137,236
931,375,123
285,801,835
680,927,924
Region 6 Region
1,361,877,000
243,859,440
5,121,048,247
27%
16,677,400
98,901,741
81,256,562
990,402,617
575,212,210
135,723,688
116,786,480
264,234,193
375,170,631
173,926,446
851,228,167
861,699,856
191,018,439
118,373,446
174,442,014
Region 5 Region
3,291,804,931
1,378,268,990
2,686,781,099
2,463,509,727
1,114,525,165
1,063,528,306
810,641,529
17,023,472,108
4%
1,945,476
2,408,213
7,089,094
5,411,179
1,393,509
6,489,073
3,141,490
14,887,020
28,968,038
22,563,036
23,071,370
30,903,436
47,582,490
35,167,698
301,380,200
356,085,929
247,006,121
122,948,195
164,385,565
441,343,406
417,601,593
Region 4 Region
108,655,816
2,281,772,131
5%
816,729
6,550,578
8,792,623
9,527,732
9,125,732
26,861,200
97,678,608
51,568,224
38,601,938
15,305,685
36,144,074
11,639,804
67,386,194
243,780,965
135,707,328
108,264,863
142,680,826
119,357,275
119,796,852
251,116,282
Region 3 Region
1,560,462,076
145,769,790
3,061,165,588
44%
1,553,761
9,515,502
8,111,480
53,229,131
16,580,367
18,646,197
67,322,704
49,932,238
27,888,638
32,559,073
40,952,595
35,128,193
65,114,121
31,872,212
198,451,000
145,732,676
211,506,829
882,993,917
Region 2 Region
2,763,096,066
7,061,545,933
16,457,236,377
1,341,855,667
28,178,969,010
13%
4,061,778
91,632,396
85,903,621
49,716,851
68,123,430
15,102,968
26,883,670
575,755,659
332,192,387
102,711,787
151,147,913
243,683,836
158,708,101
545,370,263
273,777,567
232,172,921
237,218,895
151,605,466
Region 1 Region
1,706,648,000
1,204,605,665
2,015,559,606
393,932,513
8,272,582,780
2016
2015
2014
2013
2012
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
Totals
AvgAnn
$-Losses Table 3.0.3 Annual Dollar Losses from all Weather-Related Hazards Weather-Related 3.0.3all Table from Losses AnnualDollar
% Losses %
29 CHAMPS ’17: A Hazard Assessment for Texas
County and Regional Weather-Related Hazard Dollar Losses Map 3.0.1 shows dollar losses (property plus crop losses) from all weather-related hazards over the base period by the percentage of those losses that occurred in each county. The legend indicates the percentage ranges by color. In total, each color represents 20 percent of the overall state losses for the period. This map illustrates the predominance of a hand-full of counties that had the majority of state losses. Over the 21-year base period, Harris County, with 17% of the state’s building stock, lead the state with 20% of the total losses from all weather related hazards. The next three counties (Galveston, Lubbock and Montague) combined had another 20% of the total losses. The next eight (Jefferson, Brazoria, Dallas, Bexar, Parmer, Orange, Tarrent and Cameron) combined had the third 20% of losses. Twenty-three counties make up the fourth 20% and 219 counties make up the fifth. Though Harris County losses were as high as the lowest 219 counties combined, there were no counties with zero dollar losses.
Map 3.0.1: Percent Weather-Related Hazard Dollar Losses: 1996 - 2016
30 CHAMPS ’17: A Hazard Assessment for Texas
Map 3.0.2 shows county dollar losses (property plus crop losses) from all weather- related hazards over the base period in a different way. Here each color represents 20% of Texas counties (or about 50 of 254 counties). Red, on this map, represents the 50 counties with the highest total dollar-losses over the period. As indicated above, more than 80% of the statewide losses are represented in red below. These 20-percentile groupings are used in this report to identify relative differences between count risks and as an aid is discerning overall patterns of risk. Regional Maps are used to focus more on individual county losses. The inset table below reports total dollar losses by DPS region over the period. In regional maps inset tables list total dollar losses for the highest-loss counties in those regions.
Map 3.0.2: Total Historical Weather-Related Hazard Dollar Losses
In this map, the widespread nature of weather-related hazards in Texas is apparent. Each region has at least a few counties in the highest-loss group.
31 CHAMPS ’17: A Hazard Assessment for Texas
Regional Distribution of Weather-Related Hazards Table 3.0.4 shows the distribution of all weather related hazard impacts across the regions. Totals for these categories are expressed as numbers in the upper part of the figure and percentages in the lower part. The percentages of the Property and crop losses reveal more detail about the losses reported at the bottom of table 3.0.3. For example, that table reported Region 2 with 44% of total dollar losses, this one shows that, Region 2 had 57% of all property losses and 4 % of crop losses, over the base period.
Table 3.0.4: Historical Weather Related Hazard Impacts by Region
Property Losses Crop Losses Per Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop. Losses Region 1 7,416,293,915 856,288,865 341 3,172 859.81 Region 2 27,583,631,105 595,337,905 326 2,881 3,436.10 Region 3 2,299,873,931 761,291,657 56 455 949.79 Region 4 1,404,188,409 877,583,722 31 158 928.97 Region 5 4,531,389,113 12,492,082,995 141 813 3,169.86 Region 6 4,755,036,702 366,011,545 261 6,891 832.83 Total/St. 47,990,413,175 15,948,596,689 1,156 14,370 1,730.93
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 15% 5% 29.5% 22.1% 8,625,547 Region 2 57% 4% 28.2% 20.0% 8,027,607 Region 3 5% 5% 4.8% 3.2% 2,421,457 Region 4 3% 6% 2.7% 1.1% 1,511,557 Region 5 9% 78% 12.2% 5.7% 1,429,523 Region 6 10% 2% 22.6% 48.0% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 2,285,257,770 759,456,985 55 684 82.43
Table 3.0.4 also shows that Region 1 is ahead of Region 2 with regard to the number of deaths due to weather–related hazards and that Region 6 tops all others with 48% of the hazard-related injuries. Per capita losses for the 21-year base period are shown for each region and for the state as a whole on the right (in blue). These are based on 2016 regional population estimates that are also provided. This table shows that Region 2’s $27.5 billion in property losses were about twice the per capita losses experienced statewide. The Ann Per Cap Prop Losses in the lower right, when multiplied times the 27.7 million estimated state population in 2016 equals the $2.3 billion annual average property losses over the base period.
32 CHAMPS ’17: A Hazard Assessment for Texas
Region 2 County Dollar Losses for All Weather-Related Hazards Region 2 had the highest total dollar losses from weather related hazards from 1996 to 2016: $28,178,969,010. The average annual losses for Region 2 were $1,341,855,667, and the average dollar losses per square mile per-year were $43,278 - almost 3.5 time the next highest region.
Map 3.0.3 shows total county losses (property plus crop) from all weather-related hazards over the base period for Region 2. In regional maps, such as this, county colors indicate losses relative to other counties within the Region. Each color represents approximately 20 % of the counties in the region. With 35 counties in Region 2, 7 counties are within each 20% bracket. The inset table reports the total dollar losses for the highest-loss counties. These counties are also labeled. Dollar losses in 2 counties (Harris and Galveston) totaled almost 19 Billion dollars. Over the 21-year base period, these two counties accounted for 67% of the total losses to the region and 30% of the total losses to the state.
Map 3.0.3: Region 2 Weather-Related Hazard Dollar Losses
33 CHAMPS ’17: A Hazard Assessment for Texas
Future Weather-Related Hazard Risks
In Table 3.05 below, statewide results of the forecast of weather-related hazards in Texas are presented. The methodology used to produce these forecasts is described in Appendix 2.3. Here, it is important to note that county-level impact forecasts were produced for all weather-related hazards. That these forecasts accounted for expected county population changes, building inventory changes and weather pattern changes and that forecasted county impacts were summed over the 5-year period that this state mitigation plan revision addresses (January 1, 2019 through December 31, 2023).
Table 3.0.5: Weather-Related Hazard Impact Forecasts (2019-23) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries S. COASTAL FLOOD 5,612,798,835 7 HURRICANE TS/D 5,505,055,604 1,830,531 18 779 DROUGHT 371,964,411 3,486,150,916 1 8 HAIL 2,521,001,724 166,637,326 1 35 RIVERINE FLOODING 1,139,410,241 247,575,854 96 1,918 TORNADO 560,692,305 23,115,327 22 382 WILDFIRE 328,348,462 89,490,775 15 79 S. T-STORM-WIND 338,496,656 30,697,559 12 108 WINTER WEATHER 100,081,159 3,572,851 29 319 LIGHTNING 17,560,332 269 15 64 COLD 2,972,052 514,705 4 1 HEAT 78,232 155,212 105 280 Total 16,498,460,013 4,049,741,325 326 3,974
% of Prop. % of Crop % of % of Losses Losses Deaths Injuries S. COASTAL FLOOD 34% 2% HURRICANE TS/D 33% 0% 5% 20% DROUGHT 2% 86% 0% 0% HAIL 15% 4% 0% 1% RIVERINE FLOODING 7% 6% 30% 48% TORNADO 3% 1% 7% 10% WILDFIRE 2% 2% 5% 2% S. T-STORM-WIND 2% 1% 4% 3% WINTER WEATHER 1% 0% 9% 8% LIGHTNING 0% 0% 4% 2% COLD 0% 0% 1% 0% HEAT 0% 0% 32% 7% Total 100% 100% 100% 100% The hazards in table 3.0.5 are listed in order of the magnitude of the total losses they are expected to cause over the forecast period. Two hazards moved up the
34 CHAMPS ’17: A Hazard Assessment for Texas
table from their positions in the base period. Severe Coastal Floods has moved from 4th to 1st and Wildfire has moved from 8th to 7th. For both of these hazards, their records in the NCEI Storm Events Database over the base period was incomplete. Neither had relevant data entries prior to 2005. The 12 years of data they did have was sufficient to place them 4th and 8th in the order of base period magnitude. Forecasts for these hazards was based on their total base period impacts over the 12 years the data was collected.
Regional forecasts for weather-related impacts are shown in Table 3.0.6. Region 2 is forecast to continue to have the largest property risk and to increase its share of total property dollar losses from 57% in the base period to 67% in the forecast period. This is due to the expected increase in Hurricane TS/D and Severe Coastal Flooding damages, and to the expected continuing population growth and land use development in and around Houston and the upper Texas Coast. Region 5 will continue having the largest share of crop losses
Table 3.0.6: Weather-Related Impact Forecasts by Region Property Losses Crop Losses Per Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop. Losses Region 1 1,932,083,036 217,085,161 94 821 196.60 Region 2 10,986,561,099 149,649,703 99 891 1,172.82 Region 3 652,190,066 191,463,516 15 118 246.99 Region 4 373,381,628 220,683,241 8 42 221.46 Region 5 1,194,479,946 3,179,107,457 37 206 802.32 Region 6 1,359,764,238 91,752,247 73 1,894 202.35 Total/St. 16,498,460,013 4,049,741,325 326 3,974 519.96
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 12% 5% 29.0% 20.7% 9,827,579 Region 2 67% 4% 30.4% 22.4% 9,367,616 Region 3 4% 5% 4.6% 3.0% 2,640,570 Region 4 2% 5% 2.4% 1.1% 1,686,015 Region 5 7% 79% 11.3% 5.2% 1,488,783 Region 6 8% 2% 22.4% 47.7% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses Over 5 years Ann Per Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 3,299,692,003 809,948,265 65 795 103.99
The Ann Per Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $3.3 billion annual average statewide property losses expected in the forecast: an increase of 50% over the base period $2.2 billion annual amount.
35 CHAMPS ’17: A Hazard Assessment for Texas
Forecast County and Regional Weather-Related Hazard Dollar Losses Map 3.0.4 shows the total county dollar-loss forecasts from all weather-related hazards over 2019 – 2023 for all Texas counties. The inset table reports forecast total dollar losses by DPS Region. This map illustrates what total future losses are likely to be by county given future events and event distributions similar to those in the base period.
Map 3.0.4: Weather-Related Hazard Dollar Loss Forecast
Detailed forecasts for individual hazards are presented in hazard-by-hazard discussions below along with descriptions of the nature of those hazards and the generalized nature of their risk.
Regional tables for all base and forecast period weather-related hazards are provided it Appendix 1. Appendix 1 also has detailed regional forecast maps that list total forecast losses for individual high-risk counties.
36 CHAMPS ’17: A Hazard Assessment for Texas
3.1: HURRICANES, TROPICAL STORMS AND DEPRESSIONS
Hurricanes that impact Texas start when warm tropical waters of the Gulf of Mexico or the Atlantic Ocean warm the air above them to rise into the upper atmosphere where they condensate: producing rain. These areas of relative low pressure, if they are free from interfering or sheering forces, become a self-perpetuating engine drawing in moist hot air from above the water and driving it up into the atmosphere. Quickly cyclonic (counter–clockwise) circulation begins and rain bans spin out from a wall of wind that surrounds a central area of low barometric pressure (the “eye”). Such storms can grow to a thousand miles in diameter and sustain winds near the eye that approach 200 miles an hour.
Storms like this with winds less than 39 miles an hour winds are called Tropical depressions. When the winds reach that speed, but are less than 74 miles an hour, they are called tropical storms. Storms maintaining winds of 74 or more miles an hour are called hurricanes. The Saffir-Simpson scale below is used to differentiate between hurricanes of various intensities.
Saffir-Simpson Scale Category Sustained Wind speeds 1 74 - 95 mph 2 96 – 110 mph 3 111 - 129 mph 4 130 - 156 mph 5 157 mph and above
The counterclockwise rotations of these tropical events in the norther hemisphere cause areas to the north and east of the center of the storm are to be hit the hardest. These are the areas where storm surge happens and where the winds are most severe. The abnormal rise in water levels associated with hurricanes have produced tremendous flooding events in Texas. A hurricane that hit Galveston Island in 1900 brought a storm surge that destroyed 90% of the City of Galveston and killed six to eight thousand people.
Storm surge is treated as a separate hazard in this document and analyzed under the category of Severe Coastal Flooding. Its impacts, separate from the wind and rain that comes with hurricanes, make it the fourth most destructive and expensive hazard in Texas. Severe Coastal Flooding is discussed in section 3.4 below.
37 CHAMPS ’17: A Hazard Assessment for Texas
Map 3.1.1 displays the hurricane wind risks across Texas that would be typical of a 100-yr probabilistic Hurricane. The risk zones are defined by expected wind speeds in accordance with the Saffir-Simpson wind intensity scale. Harris County is highlighted. At all return periods, the geographic area of risk are determined by one characteristic: distance from the coast. The closer to the cost, the more risk.
Map 3.1.1: Hurricane TS/D Wind Risk Zones (100-yr storm)
Source: This map was produced from data compiled for and distributed with HAZUS-MH software, by FEMA. This data was developed with the American Society of Civil Engineers (ASCE).
38 CHAMPS ’17: A Hazard Assessment for Texas
Map 3.1.2 below, displays the number of times Hurricane/TS/D Storm Tracks crossed into Texas counties between 1842 and 2010. Events are counted only if the center of the storm crossed the county boundary. The bottom 20% had zero storm tracks cross them. Harris County (highlighted) is ranked in the Top 20% of compared to other Texas counties. This map illustrates that once Hurricane TS/Ds make landfall, they frequently move inland, sometimes far inland. Counties well away from the coast are not immune from the impacts of Hurricane TS/Ds.
Map 3.1.2: Hurricane TS/D Storm Track Events by County
Source: This map was produced from the International Best Track Archive for Climate Stewardship (IBTrACS) dataset collected by NOAA’s National Climatic Data Center (NCDC).
39 CHAMPS ’17: A Hazard Assessment for Texas
Historical Experience
As with all the weather–related hazards in this study, the data used to assess the Historical experience for hurricanes, tropical storms and tropical depressions (Hurricane TS/Ds) came from the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) National Storms Database. This database contains extensive and authoritative information for weather-related events in the country from 1996 thru 2016 (a 21 year period).
Table 3.1.1 shows base period Hurricane TS/Ds impacts for each region and the state. This is the most costly of all hazards over the base period. Region 2 leads in all impact categories except for crop losses which were greatest in Region 6. Region 2 had 93% of all property losses statewide, 98 % of all deaths and more than 99% of all injuries.
Table 3.1.1: Historical Hurricane TS/D Impacts
Property Losses Crop Losses Per Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 9,075,320 2 1.05 Region 2 16,308,035,256 55 2,427 2,031.49 Region 3 1,184,538,362 2,378,470 4 489.18 Region 4 Region 5 Region 6 5,302,718 3,904,892 1 2 0.93 Total/St. 17,506,951,656 6,283,362 56 2,435 631.45
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 0.1% 0.1% 8,625,547 Region 2 93.2% 98.2% 99.7% 8,027,607 Region 3 6.8% 37.9% 0.2% 2,421,457 Region 4 1,511,557 Region 5 1,429,523 Region 6 0.0% 62.1% 1.8% 0.1% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 833,664,365 299,208 3 116 30.07
The Ann Per Cap Prop Losses, times the 27.7 million estimated state population in 2016 equals the $833.4 million annual average statewide property losses over the base period.
40 CHAMPS ’17: A Hazard Assessment for Texas
Table 3.1.2 lists the named hurricanes, tropical storms and tropical depressions that have caused damage in Texas over the 21-year base period. It shows the year and month that the events began, the name of the storm and the total dollar losses (property plus crop) that resulted.
Table 3.1.2: Historical Named Storms
Year Month Name Dollar Losses 1998 August Tropical Storm Charley 124,895 1998 September Hurricane Earl 14,693 1998 September Tropical Storm Frances 432,238,730 2001 June Tropical Storm Allison 6,964,240,773 2002 September Tropical Storm Fay 5,990,828 2003 July Hurricane Claudette 22,974,171 2003 August Tropical Storm Grace 147,083 2005 May Hurricane Rita 2,758,652,481 2007 September Hurricane Humberto 43,971,876 2008 July Hurricane Dolly 1,168,021,365 2008 August Tropical Storm Edouard 389,340 2008 September Gustav - Tropical Depression 5,562 2008 September Hurricane Ike 6,097,672,227 2010 June Hurricane Alex 137,265 2010 September Tropical Storm Hermine 18,146,434 2015 August Bill - Tropical Depression 507,295 Total 17,513,235,018
2008 Total 7,266,088,494
Though the average annual losses from hurricanes about $834 million, four events in 2008 caused $7.27 billion and one event in 2001 cause almost $7 billion. There are several years in which there were no hurricane-related losses. Between September 2010 and June 2015 there was a period of four years and nine months with zero dollar losses due to hurricane TS/Ds. This fluctuation shows the variability and challenge in predicting these potentially massively destructive events. The average Annual losses measure provides a means to gauge the relative magnitude of Hurricane TS/D impacts over time and compare that to the magnitude of other hazards.
To the right is a satellite image of Hurricane Alex from June 2010. Though Alex was among the least expensive in terms of its impact on Texas, the scale of this storm was tremendous. The Gulf of Mexico is obscured here and clouds extend from Florida to the Yucatan peninsula in Mexico.
41 CHAMPS ’17: A Hazard Assessment for Texas
Table 3.1.3 shows total dollar-losses (property plus crop) by year for all Hurricane TS/D affected regions. Region 2 received $16.3 billion of the total $17.5 billion in total losses over the period. Regions 2 and 3 both have major coastal exposures to Hurricane TS/Ds. Region 2 however has much more significant assets at risk, including the Houston Metroplex – the 4th largest urban area in the country. At the bottom of this table are the average annual dollar losses and percent of total impacts by region. Table 3.1.3: Annual Dollar-Losses from Hurricane TS/Ds
Region 1 Region 2 Region 3 Region 6 Totals 1996 1997 1998 432,224,038 154,280 432,378,318 1999 2000 2001 6,964,240,773 6,964,240,773 2002 5,990,828 5,990,828 2003 13,536,045 611,768 8,973,441 23,121,254 2004 2005 49,052 2,758,603,429 2,758,652,481 2006 2007 43,971,876 43,971,876 2008 8,520,994 6,089,468,267 1,168,021,365 77,868 7,266,088,494 2009 2010 18,283,699 18,283,699 2011 2012 2013 2014 2015 505,274 2,021 507,295 2016 Totals 9,075,320 16,308,035,256 1,186,916,832 9,207,610 17,513,235,018
Average Annual $ Losses 432,158 776,573,107 56,519,849 438,458 833,963,572 Percent 0.1% 93.1% 6.8% 0.1% 100.0%
Regions 4 and 5 are not listed here because they had no reported damage from Hurricane TS/Ds over the base period.
42 CHAMPS ’17: A Hazard Assessment for Texas
Sample Event Description: Hurricane Ike The following description of Hurricane Ike is an extract from the NCEI Storm Events database (paragraph returns were added):
The eye of Hurricane Ike moved ashore in Galveston County near the city of Galveston. At landfall, Ike had a central pressure of 951.6 mb, as measured at Galveston Pleasure Pier, and a maximum estimated storm surge of 17 feet over portions of Chambers County and the Bolivar Peninsula. Maximum sustained winds at landfall were estimated at 95 knots (110 mph) with gusts to 110 knots (127 mph). A ship near the coast recorded a wind gust of 105 knots as the eye came through.
At landfall, Ike was a Category 2 hurricane on the Saffir-Simpson scale based on wind speed, but due to its large size, had a storm surge more typical of a category 3 or 4. The height of the storm tide ranged from 4 to 6 feet in Matagorda county, 6 to 9 feet in Brazoria county, 10 to 13 feet along most of Galveston Island and Galveston Bay, to as high as 17 feet over portions of the Bolivar Peninsula and Chambers County. The majority of property damage at the coast was a result of storm tide.
Collectively, damage amounts are estimated to be near 14 billion dollars over the counties of Harris, Chambers, Galveston, Liberty, Polk, Matagorda, Brazoria, Fort Bend, San Jacinto, and Montgomery with an estimated 8 billion of that due to storm surge in coastal Galveston, Harris and Chambers Counties.
Fresh water flooding also occurred near the city of Houston where up to 14 inches of rain fell over a two day period, first from Ike, then from a line of thunderstorms associated with a cold front moving through the following day.
The number of fatalities directly related to Ike was 12 in the aforementioned counties with 11 of those occurring in Galveston County from drowning due to the storm surge. In addition, there were at least 25 fatalities indirectly related to Ike, either due to carbon monoxide poisoning from generators, accidents while clearing debris, or house fires from candles. There were no known tornadoes associated with Ike.
43 CHAMPS ’17: A Hazard Assessment for Texas
County and Regional Dollar Losses Map 3.1.3 shows total county losses (property plus crop) statewide from Hurricanes, Tropical Storms and Depressions over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had Hurricane TS/D dollar losses - white represents zero dollar losses. The inset table reports total dollar losses by DPS Region over the period.
Map 3.1.3: Historical Hurricane TS/D Dollar Losses
The many counties in Region 2 that took the majority of hurricane hazard dollar losses are made apparent by the amount of red in that area of the map.
44 CHAMPS ’17: A Hazard Assessment for Texas
Map 3.1.4 shows Region 2’s total county losses (property plus crop) from Hurricane TS/Ds over the base period. Here, colors indicate losses relative to other counties within the region. Each color represents about 20 % of the counties in the region: white represents zero dollar losses. With 35 counties in Region 2, about 7 counties are in each 20% bracket. The inset table reports the total dollar losses for the highest-loss counties in the region. These counties are also labeled.
Map 3.1.4: Historical Hurricane TS/D Dollar Losses in Region 2
The cluster of Counties with high dollar losses in the middle of this graphic represents the Greater Houston area – where hurricane Ike hit in 2008. The cluster to the north and east is the Beaumont/Port Arthur area where hurricane Rita hit in 2005. Together Harris, Jefferson and Galveston counties had 12.3 Billion dollar in damages, 70% of the total statewide for this hazard and 19% of the total statewide from all hazards over the base period.
45 CHAMPS ’17: A Hazard Assessment for Texas
Map 3.1.5 below, shows Hurricane TS/D storm tracks between 1842 and 2010 in Harris County. Storm tracks are categorized according to the Saffir-Simpson wind intensity scale assigned to each storm at its “peak magnitude” during its lifespan and not necessarily the magnitude at the time it made landfall or crossed into Harris County.
Map 3.1.6: Harris County Hurricane TS/D Storm Tracks
Source: This map was produced from International Best Track Archive for Climate Stewardship (IBTrACS) dataset from NOAA’s National Climatic Data Center (NCDC).
46 CHAMPS ’17: A Hazard Assessment for Texas
Future Risks
Results of the hazard impact forecast for Hurricane TS/Ds are presented below along with a local assessment of those risks. Following this is a discussion more generalized risk and a summary of risk statewide.
County Dollar Loss Forecast Map 3.1.6 shows the results of the forecast model for 2019-2023 for Hurricane, TS/D Dollar Losses at the county level. These are based on the locations of impacts in the base period and the likely locations of future losses.
Map 3.1.6: Hurricane TS/D Dollar Loss Forecast
This forecasts is best interpreted as estimates of damages that are likely to occur in the forecast period if similar weather events occur in similar locations as during the based period. Future Hurricane TS/D dollar losses will not necessarily be in the same places that they were in the past, but a strong correlation is likely. The local risk assessment for Harris County, below supports this assessment. 47 CHAMPS ’17: A Hazard Assessment for Texas
Local Risk Assessment: Harris County Harris County had the highest Hurricane TS/D impacts of any county in Texas over the base period and is forecast to have the highest impacts over the forecast period. The following has been extracted from the Harris County Hazard Mitigation Plan (From June 2015) showing their estimation of the hazard risk (bolding added):
Due to Harris County’s geographic location, this area of the state, and the entire planning area is vulnerable to damage from hurricane winds and to the inland impacts associated with coastal storms. Harris County is primarily impacted by coastal storm events with wind speeds in the range of 39-73 mph corresponding Tropical Storm force events on the Saffir-Simpson Hurricane Wind scale as provided above. The National Coastal Services Center shows the average wind speed from coastal storm events which have impacted Harris County at 53.2 mph with a maximum wind speed of 125 mph (Category 3 Storm on the Saffir- Simpson scale) based on past events.
Because the entire planning area is vulnerable to this hazard, Tables 4-2 [below] and 4-3 provided at the beginning of this document identify the vulnerability estimate for this hazard (total county vulnerability). Impacts to the planning area due to hurricane winds include but are not limited to: temporary and permanent displacement of residents and businesses, loss of life, widespread power outages, sewer/sanitation system damages, long-term limited mobility for residents and responders, long-term closure or limited functionality of critical infrastructure facilities including hospitals and industrial facilities, lack of economic and industrial activity due to closures. Major damage can also spread to residential property, equipment, and vehicles.
Table 4-2 Countywide Asset Inventory and Exposure
48 CHAMPS ’17: A Hazard Assessment for Texas
Regional Impact Forecast Regional forecasts for Hurricane TS/D impacts for the 5-year period 2019–2023 are shown in Table 3.1.4. The statewide expected costs of more than $5.5 billion over the period make this a very significant hazard. Region 2 can expect almost $5.1 billion of that damage and needs to remain vigilant in its mitigation and preparedness. The $350 million losses expected in Region 3, though not as high as Region 2 are still significant. The forecast of 18 deaths and 779 injuries from Hurricanes over the period means 160 people killed or injured annually.
Table 3.1.4: Hurricane TS/D Impact Forecast
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 2,759,243 1 0.28 Region 2 5,141,052,377 18 776 548.81 Region 3 359,623,196 692,919 1 136.19 Region 4 Region 5 Region 6 1,620,788 1,137,612 0 1 0.24 Total/St. 5,505,055,604 1,830,531 18 779 173.49
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 0% 0% 9,827,579 Region 2 93% 98% 100% 9,367,616 Region 3 7% 38% 0% 2,640,570 Region 4 1,686,015 Region 5 1,488,783 Region 6 0% 62% 2% 0% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 1,101,011,121 366,106 4 156 34.70
The Ann Per-Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $1.1 billion annual average statewide property losses expected in the forecast period. This is an increase of 32% over the base period $833.6 million annual amount. This increase is due to a combination of population growth and building exposure increases as well as expected increasing Hurricane TS/D-related damage due to weather pattern changes.
49 CHAMPS ’17: A Hazard Assessment for Texas
Risk Summary A review of the historical record shows that damaging Hurricane TS/Ds hit Texas every 1.3 years (an annual average probability of 75%). The average annual historical dollar losses were $834 million and the annual forecast dollar losses are $1.1 Billion. The total forecast dollar losses for the 5-year forecast period are $5.5 Billion. Future impacts may be more or less than forecast, but these forecasts are a reasoned extension of recent Texas historical experience
The highest damage from Hurricane TS/Ds during the base period occurred in the highly developed and populated Greater Houston Area. This is expected to continue to be the case in the future. If future events occur in less developed and less populated regions, overall impacts may be less than what is forecasted here. However, if more damaging storms or more storms overall bare-down on the Texas coast, greater, perhaps much greater, impacts than also may occur – Harris County considers itself as having “total county vulnerability”
Hurricanes have been the most expensive natural hazard in Texas. Together with the Severe Coastal Floods that accompanies them, these hazards caused approximately $28 billion in losses over the 21-year base period: $1.3 billion a year. The forecast for Hurricane TS/Ds and Severe Coastal Flooding is for them to cause $11.1 billion in losses over the 5-year forecast: $2.2 billion a year.
Over the base period 19% of total statewide losses from all weather–related hazards came from Hurricane TS/D losses in Harris, Jefferson and Galveston counties. These three counties are forecast to have $3.9 Billion dollars in losses from Hurricane TS/Ds in the forecast period. Hurricane TS/Ds are forecast to cause 46% of the dollar losses from all weather-related hazards in Region 2 and 27% of that figure statewide.
All coastal counties in Texas are equally likely to be hit. The more populated and developed they are, the more damage, loss of life and injury that will result. Differences in the location of future vs past events may result in lower impacts than forecast, but may also cause higher than forecast damages. Hurricanes are capricious in their timing and locations. They can spin up quickly, do significant damage and can also move inland and react with other weather systems to produce additional damages.
All areas along the coast and three to four counties inland need to mitigate for Hurricane TS/Ds and otherwise be ready to deal with the damages they create.
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3.2: DROUGHT
Drought is the consequence of a natural reduction in the amount of precipitation expected for a given area or region over an extended period of time, usually a season or more in length. Two-thirds of Texas counties are in arid or semi-arid climate, and are almost always in varying stages of drought. For precipitation, these counties normally depend on large, but infrequent tropical systems that move out of the Gulf of Mexico in late summer and early fall or by springtime Pacific systems that move easterly over these counties.
The following description of drought measures comes from a NOAA’s National Centers for Environmental Information article: DROUGHT: Degrees of Drought Reveal the True Picture. It explains the measures of drought from NOAA’s United States Drought Monitor (USDM) shown in the graphic on the following page.
The USDM’s drought intensity scale is composed of five different levels:
D0, abnormally dry corresponds to an area experiencing short-term dryness that is typical with the onset of drought. This type of dryness can slow crop growth and elevate fire risk to above average. This level also refers to areas coming out of drought, which have lingering water deficits and pastures or crops that have not fully recovered..
D1, moderate drought, corresponds to an area where damage to crops and pastures can be expected and where fire risk is high, while stream, reservoir, or well levels are low.
D2, severe drought, corresponds to an area where crop or pasture losses are likely, fire risk is very high, water shortages are common, and water restrictions are typically voluntary or mandated.
D3, extreme drought, corresponds to an area where major crop and pasture losses are common, fire risk is extreme, and widespread water shortages can be expected requiring restrictions.
D4, exceptional drought, corresponds to an area experiencing exceptional and widespread crop and pasture losses, fire risk, and water shortages that result in water emergencies.
51 CHAMPS ’17: A Hazard Assessment for Texas
The graphic below illustrates the percent of the state that was under various stages of drought from January 1, 2010 to April 1, 2016. It shows that: For the four and a half years from November 2010 to June 2015, more than 50% of the state was in some level of drought; For the 11 months from April 2011 to February 2012, 100% of the state was in some level of drought; and At the peak of this drought, in October-November 2011, approximately 90% of the state was in Exceptional Drought (D4). Financial and other impacts of this protracted event are discussed in the Historical Experience section that follows this graphic.
52 CHAMPS ’17: A Hazard Assessment for Texas
Historical Experience
The data used to assess the Historical experience for drought came from the NOAA’s NCEI National Storms Database. This database contains extensive and authoritative information for weather related event in the country from 1996 thru 2016 (a 21 year period).
Table 3.2.1 below shows drought Impacts over the base period. All regions suffered losses from Drought in the hundreds of millions of dollars. The highest region, Region 5 suffered losses of more than $11-billion in crop losses and more than $1-billion in property losses. The lowest region, Region 3, in south Texas, suffered losses of more than $269 million in crop losses and more than $90 million in property losses. More than 90 percent of the dollar losses from drought are due to crop losses
Table 3.2.1: Historical Drought Impacts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 15,128,672 820,386,729 1.75 Region 2 32,336,396 500,014,063 4.03 Region 3 91,790,648 268,002,805 37.91 Region 4 41,440,402 796,987,279 2 27.42 Region 5 1,089,517,981 11,146,482,645 5 30 762.15 Region 6 130,396,702 286,270,584 22.84 Total/St. 1,400,610,801 13,818,144,105 5 32 50.52
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 1% 6% 8,625,547 Region 2 2% 4% 8,027,607 Region 3 7% 2% 2,421,457 Region 4 3% 6% 6% 1,511,557 Region 5 78% 81% 100% 94% 1,429,523 Region 6 9% 2% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 66,695,752 658,006,862 0 2 2.41
Drought was the second most expensive weather-related hazard over the base period. The Ann Per-Cap Prop Losses, times the 27.7 million estimated 2016 state population equals the $66.7 million annual average statewide property losses. Note that the average annual Crop Losses are 10 times those of property losses.
53 CHAMPS ’17: A Hazard Assessment for Texas
Table 3.2.2 shows total dollar-losses (property plus crop losses) by year for drought in Texas over the base period. The relative severity of Region 5’s impacts are apparent in this table. The totals show that it received $12.2 billion of the $15.2 billion total losses over the period (over 80% of the losses statewide). More than 90% of these losses were from crop damage. Table 3.2.2: Annual Dollar-Losses from Drought
Region 1 Region 2 Region 3 Region 4 Region 5 Region 6 Totals 1996 6,105,800 164,856,598 288,315,871 140,738,688 366,347,992 966,364,949 1997 105,947,041 11,937,695 117,884,736 1998 220,398,773 268,298,778 431,724,462 1,037,894,555 12,195,399 1,970,511,967 1999 2000 142,281,359 3,599,454 118,220,093 805,287,457 1,069,388,363 2001 33,822,106 567,984,190 601,806,296 2002 119,817 119,817 2003 19,524 312,391,304 312,410,828 2004 2005 73,579,109 1,006,022,645 1,079,601,754 2006 529,727,435 120,700,397 2,162,307,219 18,948,540 2,831,683,591 2007 69,320 231,067 415,920 716,307 2008 183,546 77,868 450,522 1,051,218 1,763,154 2009 196,516 155,205 23,112,587 27,914 36,489,980 1,878,046 61,860,248 2010 41,729 59,298 85,654 76,868 263,549 2011 3,698,477 683,678 28,455,667 2,487,837,405 3,155,896 2,523,831,123 2012 176,281 39,637 1,344,770,593 182,540 1,345,169,051 2013 552,020 40,090 2,309,899,394 300,164 2,310,791,668 2014 604,056 23,555,883 117,880 24,277,819 2015 175,339 14,149 54,070 59,128 302,686 2016 7,000 7,000 Totals 835,515,401 532,350,459 359,793,453 838,427,681 12,236,000,626 416,667,286 15,218,754,906
Average Annual $ Losses 39,786,448 25,350,022 17,133,022 39,925,128 582,666,696 19,841,299 724,702,615 Percent 5.5% 3.5% 2.4% 5.5% 80.4% 2.7% 100.0%
Though the average annual dollar losses from Property and crop losses over the base period was $725 million, the average annual dollar losses for the period 2011 through 2013 was $2 Billion. These three years were the peak years of the protracted drought shown in the time series figure above. Drought and Water Supply Issues
Surface and groundwater supplies are used to water crops, for industrial purposes, for domestic purposes, for drinking water and to support various water-dependent habitats, including rivers, marshes and estuaries. Managing water supplies to keep all of these uses viable through exceptional drought, such as the state experienced in the 2011 – 2013 period is a complicated, expensive and, sometimes, impossible, task. Environmental damages and losses to habitat are not included in the costs above.
54 CHAMPS ’17: A Hazard Assessment for Texas
Sample Event Descriptions: Drought
Below are two extracts from the NCEI Storm Events Database describing drought events. The following drought event description is of a dust storm that occurred on December 19, 2012 (paragraph returns added):
A historic dust storm engulfed much of the South Plains this afternoon resulting in dust storm conditions (visibilities at or below 1/2 mile in blowing dust) at the Lubbock International Airport for the longest duration since December 16, 1977. The culprit for this exceptional dust storm was a surface cyclone rapidly deepening in far southwest Kansas ahead of a vigorous upper level trough exiting the southern Rockies. Along the southern periphery of this trough, a deep layer wind maximum overspread the Texas South Plains during the afternoon behind a Pacific cold front. Initially, a layer of thick high clouds prevented these winds from mixing to the surface behind the front, but as the late morning and afternoon wore on, these clouds departed and allowed high winds with frequent gusts around 60 mph to stir up extensive blowing dust on the Caprock.
The highest wind gusts as measured by the Texas Tech University West Texas Mesonet developed in Lubbock and Floyd Counties where peak wind gusts of 66 and 72 mph were recorded, respectively. Visibilities fell abruptly to 1/2 mile or less in many rural areas, with near-zero visibility at times as documented by TV news reporters along Interstate 27 in southern Hale and northern Lubbock Counties.
These conditions contributed to a deadly 25-vehicle pileup on I-27 just south of New Deal. One man was fatally injured and at least 17 others suffered injuries of varying severity. Law enforcement promptly closed the interstate in both directions for several hours. Also, a mobile triage unit from UMC Hospital was dispatched for the first time ever to assist with accident victims as flight-for-life helicopters were grounded due to the high winds.
An unknown number of less significant vehicle accidents were reported throughout the city of Lubbock and also along Highway 84 near Slaton. At the Lubbock Airport, all air traffic was suspended during the afternoon resulting in additional stress for holiday travelers. Widespread power outages were noted primarily in northern sections of Lubbock and also in Levelland - west of Lubbock - after high winds damaged power lines.
The high winds also created sporadic instances of minor property damage. Much of this damage consisted of damaged fences, fallen tree limbs, and damage to outdoor Christmas lights and lawn decorations. These damages along with the total economic impacts will likely push combined losses to $1 million.
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The following extract from a drought event description discusses the general conditions and damages that occurred in December 2005 in Montague County, on the Oklahoma border northwest of Dallas - (paragraph returns added):
Devastating drought conditions continued through December. The area of extreme drought (D3) as classified by the U.S. Drought Monitor expanded to include roughly the northeast quarter of the state of Texas. For the first time since the drought began in May, an area of exceptional drought (D4) was introduced into the Drought Monitor. This is the most severe classification of drought and included a large area of north Texas, including the Dallas/Fort Worth Metroplex.
Dallas/Fort Worth ended the year at 15.76 inches below normal, while Waco was 10.09 inches below normal, making this the worst drought in north Texas since the 1950s. Collin, Delta, Fannin, Hopkins, Lamar, and Rains Counties were declared natural disaster areas due to extreme drought conditions. Requests for disaster drought declarations were also pending for numerous other north Texas counties.
… Governor Rick Perry asked for federal disaster declarations after several dozen fires burned on December 27-28. According to the state emergency management agency, fires on Dec. 27-28 destroyed more than 100 buildings across Texas, including 78 homes. Because of widespread drought conditions, outdoor burning bans were in effect in 104 of the state's 254 counties, and 86 counties banned aerial fireworks for the 11-day fireworks season that ran through New Year's Day.
According to the Texas Cooperative Extension, the monetary damages for the 2005 drought have been estimated at $60 million for north central Texas. The federal government estimated that the national net farm income for 2005 was down nearly $11 billion from 2004, with losses in Texas accounting for a significant portion of the decline. Hay and pasture losses were estimated at 70% by the Farm Service Agency. Due to the hay shortage, prices drastically increased, and feeding costs reportedly went up at least 50%. Ranchers were forced to feed their livestock supplemental hay and protein for an extra three to five months. Farmers also sold lighter calves for lower prices because they did not have enough grazing for the winter. The remaining lighter calves will also bring a lower price next year. In addition, ranchers struggled with dwindling water supplies as stock tanks throughout Texas ran low.
Many lakes in north Texas were 10 to 15 feet below normal pool elevation. The drought also caused numerous other problems, including cracked foundations and an increase in pest problems, as animals looked indoors for food.
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County and Regional Dollar Losses
Map 3.2.1 shows total county losses (property plus crop losses) from drought over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had drought dollar losses -white represents zero dollar losses. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.2.1: Historical Drought Dollar Losses
Region 5 had 80% of all dollar losses statewide, 100 % of all deaths and more than 93% of all injuries from drought. Montague County, population 20 –thousand, (the one discussed in the second drought event description above) is the east-most county in Region 5. It is colored red above, indicating that it was in the upper 20% of Texas counties in terms of Drought dollar losses over the period.
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Map 3.2.2 shows Region 5 total county losses (property plus crop losses) from Drought. County colors indicate their losses relative to other counties within the region. Each color represents approximately 20 % of the region’s counties. With 71 counties in Region 5, approximately 14 counties are within each 20% bracket. The inset table in this map reports the total dollar losses for the highest-loss counties. These counties are also labeled.
Map 3.2.2: Historical Drought Dollar Losses in Region 5
The inset table shows that Montague County (on the right-side of the map) experienced about $2.5 Million in drought related dollar losses - the second highest in the region over the base period. Lubbock, Montague and Parmer, listed in the inset table, experienced higher dollar losses from drought than any counties in the state or region.
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Future Risks
Results of the hazard impact forecast for Drought are presented below along with a local assessment of those risks. Following this is a discussion more generalized risk and a summary of risk statewide.
County Dollar Loss Forecast Map 3.2.3 shows the results of the forecast model for 2019-2023 for Drought dollar losses at the county level. These show locations of drought impacts in the base period and the likely locations of future losses.
Map 3.2.3: Drought Dollar Loss Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations as during the based period. Future Drought dollar losses will not necessarily be in the same places that they were in the past, but a strong correlation is likely. The local risk assessment for drought in Lubbock County below supports this assessment.
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Local Risk Assessment: Lubbock County Lubbock County had the highest Drought impacts of any county in Texas over the base period and is forecast to have the highest impacts over the forecast period. The following has been extracted from the Lubbock County Hazard Mitigation Plan (from January 2015) showing their estimation of drought hazard risk:
Loss estimates were based on 62 years of statistical data from the NCDC. A drought event frequency-impact was then developed to determine an impact profile on agriculture products and estimate potential losses due to drought in the area. The table below shows annualized exposure and estimated loss.
Drought impacts large areas and crosses jurisdictional boundaries. All existing and future buildings, facilities and populations are exposed to this hazard and could potentially be impacted in the entire Lubbock County planning area. However, drought impacts are mostly experienced in water shortages and crop/livestock losses on agricultural lands and typically have no impact on buildings.
The economic impact of droughts can be significant as they produce a complex web of impacts that spans many sectors of the economy and reach well beyond the area experiencing physical drought. This complexity exists because water is integral to our ability to produce goods and provide services. If droughts extend over a number of years, the direct and indirect economic impact can be significant.
Based on the nine reported previous occurrences and potential exposure for the hazard, the potential severity of impact of droughts is minor for the Lubbock County planning area and the campuses of Frenship ISD, Idalou ISD, Lubbock ISD, Lubbock-Cooper ISD, New Deal ISD, Roosevelt ISD, Shallowater ISD, Slaton ISD, South Plains College, Texas Tech University System, Lubbock County Hospital District, Lubbock County Water Control District #1, and SPAG (South Plains Association of Governments) with more than 10% of property destroyed. Annualized loss over the 62-year reporting period in Lubbock County is $41.7 million.
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Regional Impact Forecast Regional forecasts for Drought impacts for the 5-year period 2019–2023 are shown in Table 3.2.3. Total expected statewide costs for drought in the forecast period are $3.86 billion. Region 5 can expect almost $3.1 billion in losses: 80% of the statewide total. Deaths and injuries will likely come from car accidents during dust storm conditions.
Table 3.2.3: Drought Impact Forecast Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 4,054,762 206,973,666 0.41 Region 2 8,678,269 126,147,511 0.93 Region 3 23,204,315 67,613,872 8.79 Region 4 11,777,673 201,070,268 1 6.99 Region 5 290,341,921 2,812,122,987 1 8 195.02 Region 6 33,907,471 72,222,612 5.05 Total/St. 371,964,411 3,486,150,916 1 8 11.72
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 1% 6% 9,827,579 Region 2 2% 4% 9,367,616 Region 3 6% 2% 2,640,570 Region 4 3% 6% 6% 1,686,015 Region 5 78% 81% 100% 94% 1,488,783 Region 6 9% 2% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 74,392,882 697,230,183 0 2 2.34
The average annual dollar losses from Droughts over the forecast period are expected to increase 6% (over the base period). This increase is due to a combination of population and building exposure increases and expected increasing Drought-related damage due to weather pattern changes.
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Risk Summary With expected statewide dollar losses of $3.85 billion over the forecast period and $770 million a year, Drought remains a persistent and dangerous hazard in Texas. There were 2,179 reports of Drought impacts over the base period (12.7 times as many as for Hurricane TS/D). These provide a good basis for determining both the magnitude and the locations of future losses. The 2,179 data points that went into the model help produce a reliable depiction of how much damage there is likely to be in the future, and where that damage will likely occur.
Map 3.2.4 shows the Drought dollar loss forecast for 2019 – 2023 in Region 5 – the most at-risk region. This map, together with the statewide forecast map (Map 3.2.3) and the regional forecast table (Table 3.2.3) provide the best picture of expected future risks.
Map 3.2.4: Forecast Drought Dollar Losses in Region 5
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Since property damage, from the contracting expansive soils is included in drought- loss assessments, it is appropriate to consider where these soils are when considering future risk from Drought.
The most expansive soils in Texas are in two bands (shown in red below). The first band is parallels the coastline about 200 miles, stretching approximately from near Brownsville in the south to near Beaumont on the Louisiana boarder. The second band runs from near Laredo in the south, easterly through San Antonio and then northeasterly through Austin and Dallas. This area, from San Antonio to Dallas is generally referred to as the I-35 Corridor, is highly populated. Alternating periods of moisture and drought, cause the soils in these soils to expand and contract frequently producing serious foundation problems for those living there. The teal color that covers most of Texas on the map below also has high swelling potential and increased property damage risk from drought.
Location of varying types of expansive soils across Texas
Unit contains abundant clay: high swelling potential
Part of unit (generally less than 50%) consists of clay: high swelling potential
Unit contains abundant clay: slight to moderate swelling potential
Part of unit (generally less than 50%) consists of clay: slight to moderate swelling potential
Unit contains little or no swelling clay
Data insufficient to indicate clay content of unit and/or swelling potential of clay.
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3.3: HAILSTORMS
Hail is a form of solid precipitation. It consists of balls or irregular lumps of ice, each of which is called a hailstone. Hailstones usually measure between 5 millimeters (0.2 in) and 15 centimeters (6 in) in diameter. Hail is possible within most thunderstorms as it is produced by cumulonimbus. Hail formation requires environments of strong, upward motion of air (similar to tornadoes) and lowered heights of the freezing level. In the mid-latitudes, hail forms near the interiors of continents, while in the tropics, it tends to be confined to high elevations. Any thunderstorm which produces hail that reaches the ground is known as a hailstorm.
Like other precipitation in cumulonimbus clouds, hail begins as water droplets. As the droplets rise and the temperature goes below freezing, they become super cooled water and will freeze on contact with condensation nuclei. A cross-section through a large hailstone shows an onion-like structure. This means the hailstone is made of thick and translucent layers, alternating with layers that are thin, white and opaque.
The storm's updraft blows the forming hailstones up the cloud. As the hailstone ascends it passes into areas of the cloud where the concentration of humidity and super cooled water droplets varies. When the hailstone moves into an area with a high concentration of water droplets, it captures the latter and acquires a translucent layer. Should the hailstone move into an area where mostly water vapor is available, it acquires a layer of opaque white ice.
The hailstone will keep rising in the thunderstorm until its mass can no longer be supported by the updraft. It then falls toward the ground while continuing to grow, based on the same processes, until it leaves the cloud. It will later begin to melt as it passes into air that is above freezing temperature
The following is from Dallas County’s Hazard mitigation plan:
The severity of damage caused by hailstorms depends on the hailstone sizes (average and maximum), number of hailstones per unit area, and associated winds. Storms that produce high winds in addition to hail are most damaging and can result in numerous broken windows and damaged siding.
The NOAA/TORRO Hailstorm Intensity Scale as seen in Table 5.3 is representative of the damage from hail storms Dallas County has experienced in the past and will likely experience in the future. For example, in April of 2012 a hail storm produced up to 2.0 inches (a size code of H5 with an intensity category of destructive) in the City of Duncanville causing property damage cost of $1.2 million.
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The Hailstorm Intensity Scale allows planners to gauge past damage and mitigate for future expected damage.
Hailstorms can cause extensive property damage affecting both urban and rural landscapes. Fortunately, most hailstorms produce marble-size or smaller hailstones. These can cause damage to crops, but they normally do not damage buildings or automobiles. Larger hailstones can destroy crops, livestock, and wildlife and can cause extensive damage to buildings, including roofs, windows, and outside walls. Vehicles can be total losses. When hail breaks windows, water damage from accompanying rains can also be significant. A major hailstorm can easily cause damage running into the millions of dollars.
In April 2012 a hailstorm in San Antonio caused between 1.36 and 2 Billion dollars of damage. That was the most expensive hailstorm on record in Texas. It discussed in the sample event description below.
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Historical Experience
All Regions suffered losses from Hailstorms over this period. They were the third most costly weather-related hazard in the 21 year base period statewide. In four of six regions, hailstorms did more property damage than any other weather-related hazard. In Region 1, 54% of property losses were from hailstorms; In Region 4, 66% of property losses were from hailstorms; In Region 5, 47% of property losses were from hailstorms; and In Region 6, 48% of property losses were from hailstorms.
Table 3.3.1 shows property and crop losses as well as deaths and injuries directly or indirectly attributed to Hailstorms. It also shows regions 1, 5 and 6 had property losses between 2 and 4 billion dollars each, that Region 4’s losses were almost a billion and that Region 5’s $571.8 million in crop losses constitute 82% of all crop losses from hailstorms statewide.
Table 3.3.1: Historical Hailstorm Impacts Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 3,999,702,350 112,325 1 11 463.70 Region 2 84,362,539 10,421,568 10.51 Region 3 308,135,247 1,524,207 1 13 127.25 Region 4 931,110,308 67,569,148 63 615.99 Region 5 2,108,185,898 571,442,441 3 33 1,474.75 Region 6 2,285,536,463 48,807,081 20 400.30 Total/St. 9,717,032,805 699,876,770 5 140 350.48
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 41% 0% 20% 8% 8,625,547 Region 2 1% 1% 8,027,607 Region 3 3% 0% 20% 9% 2,421,457 Region 4 10% 10% 45% 1,511,557 Region 5 22% 82% 60% 24% 1,429,523 Region 6 24% 7% 14% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 462,715,848 33,327,465 0 7 16.69
The Ann Per-Cap Prop Losses, times the 27.7 million est. 2016 state population equals the $463 million annual average base period property losses statewide.
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Table 3.3.2 shows total hailstorm dollar-losses (Property plus Crop Losses) by year and by region over the base period. The relative severity of Region 1’s impacts are apparent in this table. The totals show that it received $4 billion of the $10.5 billion total losses (38% of the statewide losses). Almost all of these losses were in property damage.
Table 3.3.2: Annual Dollar-Losses from Hailstorms
Region 1 Region 2 Region 3 Region 4 Region 5 Region 6 Totals 1996 112,134,539 16,020,071 4,579 85,137,745 16,342,161 305,457,901 535,096,996 1997 1,228,083 9,092,048 87,086,973 358,130 97,765,234 1998 8,081,288 777,275 308,558 4,042,114 14,490,481 15,288,329 42,988,045 1999 7,489,766 16,911,648 129,382 155,062,594 145,397,075 1,190,313 326,180,778 2000 39,243,508 19,784,464 180,806 1,536,861 34,472,973 11,356,081 106,574,693 2001 338,086 30,350,646 206,908 689,695 260,443,740 204,774,528 496,803,603 2002 1,419,148 1,464,427 28,047,728 54,621,722 3,042,011 88,595,036 2003 22,362,014 562,304 65,081,522 27,159,822 51,375,685 152,291 166,693,638 2004 12,679 2,476,775 8,982,834 9,334,035 246,459,328 1,224,759 268,490,410 2005 82,164 1,130,675 2,472,875 2,522,537 122,894,280 129,102,531 2006 388,476 830,412 184,140 5,335,647 26,379,453 125,925,204 159,043,332 2007 21,076,692 406,677 109,756 14,086,370 40,456,207 40,438 76,176,140 2008 159,885,438 204,123 1,112 4,310,554 10,494,949 741,970 175,638,146 2009 106,554,345 280,260 3,350 351,639,037 58,789,728 178,776,986 696,043,706 2010 490,859 18,668 49,416 227,310 54,981,226 131,773 55,899,252 2011 6,593,026 69,221 1,102,190 7,455 1,110,712 876,001 9,758,605 2012 1,255,323,392 88,662 221,013,334 152,816 21,371,202 1,264,261 1,499,213,667 2013 1,575,762 1,993,092 6,874,573 5,345 514,199,353 150,072 524,798,197 2014 561,483,311 35,921 1,618,927 45,026 423,381,762 439,132 987,004,079 2015 846,330 93,982 396,640 173,379 613,328,672 56,084 614,895,087 2016 1,695,853,000 102,000 1,947,000 300,121,000 1,922,400 1,360,203,000 3,360,148,400 Totals 3,999,814,675 94,784,107 309,659,454 998,679,456 2,679,628,339 2,334,343,544 10,416,909,575
Average Annual $ Losses 190,467,365 4,513,529 14,745,688 47,556,165 127,601,349 111,159,216 496,043,313 Percent 38.4% 0.9% 3.0% 9.6% 25.7% 22.4% 100.0%
With an average cost of roughly $500 million a year and regular occurrences in all regions, hailstorms have been a constant and persistent hazard in Texas.
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Sample Event Description: San Antonio Hailstorm of April 2016
The following narrative and map describe an event that happened on April 12, 2016 in San Antonio (from the NCEI Storm Events Database). Though San Antonio is not in Region 1 - the highest loss region, this event is a significant one in and of itself: It is reported to be one of the single most expensive hailstorm events on record. – Though it is reported to have cost $1.36 to $2 billion. There was no presidential disaster declaration following this event.
A thunderstorm produced 4.5 inch hail near Tezel Rd. and Bandera Rd. in northwestern San Antonio. This tied for the largest hailstone ever reported in Bexar County. The hailstorm moved across northern Bexar County, crossing the northern half of San Antonio. Damage costs in San Antonio are estimated at $1.36 billion making this the costliest hail storm ever in the state of Texas according to the Insurance Council of Texas. Estimates do not include uninsured or commercial losses which will likely push the losses to near 2 billion, especially when including 2 other hail storms that occurred over the same area of Bexar County at the end of the April. Estimates provided by the Insurance Council of Texas and include damage to 136,000 vehicles and 125,000 homes.
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County and Regional Dollar Losses
Map 3.3.1 shows total county losses (property plus crop losses) from Hail Storms over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had these sorts of impacts -white represents zero dollar losses. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.3.1: Historical Hailstorm Dollar Losses
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Map 3.3.2 shows Region 1 total county losses (property plus crop losses) from Hail Storms. County colors indicate their losses relative to other counties within the region. Each color represents approximately 20 % of the region’s affected counties. With 42 counties in Region 1, and 9 unaffected, 6 to 7 counties are within each 20% bracket. The inset table reports the total dollar losses for the highest-loss counties. These counties are also labeled.
Map 3.3.2: Historical Hailstorm Dollar Losses in Region 1
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Future Risks
Results of the hazard impact forecast for Hailstorms are presented below along with a local assessment of those risks. Following this is a discussion more generalized risk and a summary of risk statewide.
County Dollar Loss Forecast
Map 3.3.3 shows the county forecasts for 2019-2023 for Hailstorm dollar losses. These illustrate likely locations of future losses.
Map 3.3.3: Hailstorm Dollar Loss Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations as during the based period. Future Hailstorm dollar losses will not necessarily be in the same places they were in the past, but a strong correlation is likely. The local risk assessment for Hailstorms in Dallas County below supports this forecast.
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Local Risk Assessment: City of Dallas Dallas County had the highest values for Hailstorm impacts of any county in Texas over the base period and is forecast to have the highest impacts over the forecast period. The following has been extracted from the City of Dallas Hazard Mitigation Plan (From November 2015) showing their estimation of hailstorm hazard risk:
Hail affects the entire planning area equally. The following map depicts hail events in the Dallas County from 2006 to 2013.
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... Hailstorms can cause extensive property damage affecting both urban and rural landscapes. Fortunately, most hailstorms produce marble-size or smaller hailstones. These can cause damage to crops, but they normally do not damage buildings or automobiles. Larger hailstones can destroy crops, livestock, and wildlife and can cause extensive damage to buildings, including roofs, windows, and outside walls. Vehicles can be total losses. When hail breaks windows, water damage from accompanying rains can also be significant. A major hailstorm can easily cause damage running into the millions of dollars.
… Due to the rapidly changing climate patterns in Texas, large scale hailstorms are especially prevalent. Hailstorm incidents have been reported throughout the region therefore establishing that all parts of region are equally vulnerable to hailstorms.
Hailstorms affect the entire planning area equally and the probability of recurrence is high.
Dallas County and participating jurisdictions experienced 139 hail events ranging from magnitude H2 (.75 inch diameters) to magnitude H10 (4+inch diameters), during the time period analyzed for this plan (01/01/2008 through 06/30/2013). It can be expected that any future hail events will be similar in magnitude.
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Regional Impact Forecast Regional forecasts for Hailstorm impacts for the 5-year period 2019–2023 are shown in Table 3.3.3. Total expected statewide costs are $2.5 billion. Region 1 can expect $1 billion in losses: 42% of the statewide total. The zeros in the forecasts deaths column below mean that deaths are forecast by the model, but in numbers lower than .5 (1/2 person) over 5 years.
Table 3.3.3: Hailstorms Impact Forecast Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 1,056,441,753 26,744 0 3 107.50 Region 2 22,158,016 2,481,326 2.37 Region 3 78,061,898 362,906 0 3 29.56 Region 4 244,895,217 16,087,892 16 145.25 Region 5 518,817,233 136,057,724 1 8 348.48 Region 6 600,627,607 11,620,734 5 89.38 Total/St. 2,521,001,724 166,637,326 1 35 79.45
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 42% 0% 21% 8% 9,827,579 Region 2 1% 1% 9,367,616 Region 3 3% 0% 21% 9% 2,640,570 Region 4 10% 10% 45% 1,686,015 Region 5 21% 82% 57% 23% 1,488,783 Region 6 24% 7% 15% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 504,200,345 33,327,465 0 7 15.89
The Ann Per-Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $504 million annual average statewide property losses expected in the forecast period. This is an increase of 8% over the base period $462.7 million annual amount. This increase is due to population growth and building exposure increases in the impacted areas. There are no expected changes to Hailstorms damage due to weather pattern changes. Hailstorms are not expected to become more frequent or more damaging.
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Risk Summary With expected dollar losses over $2.7 billion over the forecast period and $500 million a year, Hailstorms are a persistent and dangerous hazard in Texas. There were 4,277 reports of Hailstorm impacts over the base period (25 times as many as for Hurricane TS/D). These provide a good basis for determining both the magnitude and the locations of future losses. The 4,277 data points that went into the model help produce a reliable depiction of how much damage there is likely to be in the future, and where that damage will likely occur.
Map 3.3.4 shows the Hailstorm dollar loss forecast for 2019 – 2023 in Region 1 – the most at-risk region. This map, together with the statewide forecast map (Map 3.3.3) and the regional forecast table (Table 3.3.3) provide the best picture of expected future risks.
Map 3.3.4: Forecast Hailstorm Dollar Losses in Region 1
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3.4: SEVERE COASTAL FLOODING
Severe Coastal Flooding, also called storm surge, is caused by hurricane-level tropical storm events. The nature of the damage it produces, and the way to mitigate for it, are more similar to Riverine Flooding than to Hurricane TS/Ds. To manage storm surge planning and response in Texas, the Gulf coast is divided into five basins. These basins are used in estimating storm surge likelihood and extent. They are also used as the basic geographic units for preparing hurricane evacuation plans. Map 3.4.4 shows the Storm surge basins in Texas
Map 3.4.1: Texas Storm Surge Basins
Source: This map was derived from the storm surge basin analysis in the NOAA/SLOSH Program.
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The Map below shows expected inundation areas associated with Hurricane storm surge based on the category of the storm. These MOM Storm Surge footprint are the worst case storm surge scenarios for each Saffir-Simpson hurricane category (1 through 5) under perfect storm conditions. They are provided in the Coastal Flood Loss Atlas (CFLA) developed by FEMA Region IV. Each storm surge risk zone is defined by the area likely to be inundated by storms of the indicated category. All lower level risk zones are contained within the risk zones for higher category storms. The predominance of the color red near the northern Gulf coast of Texas illustrates that this area is the most at risk from this hazard.
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Historical Experience
This was the fourth most expensive weather-related hazard in Texas over the 21 year base period. Table 3.4.1 shows Severe Coastal Flooding-related property losses, crop losses, deaths and injuries from 1996 through 2016. All three regions with counties on the coast Texas suffered losses over this period, but Region 2’s losses constitute 99.9% of the overall losses. Regions 1, 3, 4 and 5 had no losses from this hazard.
Table 3.4.1: Historical Severe Coastal Flooding Impacts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 Region 2 10,354,386,036 13 1,289.85 Region 3 9,957,716 4.11 Region 4 Region 5 Region 6 1,313,713 0.23 Total/St. 10,365,657,465 13 373.87
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 8,625,547 Region 2 99.9% 100.0% 8,027,607 Region 3 0.1% 2,421,457 Region 4 1,511,557 Region 5 1,429,523 Region 6 0.0% 5,709,501 Total/St. 100.0% 100.0% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 493,602,736 1 17.80
Statewide Annual Losses over 12 years Ann Per Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 863,804,789 1 31.16
The annual average dollar losses due to Severe Coastal Flooding over the 21 year period 1996 thru 2016 was $493,602,736. However, a closer look at the data (below) reveals that data for this category was only collected since 2005. Dividing the total by the 12 years of data collection places annual cost of this hazard at $863,804,789, higher than Hurricane TS/D – otherwise the highest risk hazard.
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Table 3.4.2 shows total dollar-losses by year for Severe Coastal Flooding over the last 12 years. The NCEI database includes no entries for this hazard prior to July 2005. A review of the data indicates that prior to 2005, Severe Coastal Flooding was reported under the Hurricane category – and only identified in the damage descriptions, not as a category unto itself. For this reason, the average annual cost information used for this hazard (show at the bottom of this table) is calculated over 12 years and not the standard 21 years of the base period used for other hazards. To use the 21-year period would reduce annual average losses and the forecasted impacts by 43%.
Table 3.4.2: Annual Dollar-Losses from Severe Coastal Flooding
Region 2 Region 3 Region 6 Totals 2005 49,053 49,053 2006 2007 2008 10,354,336,983 9,919,282 10,364,256,265 2009 2010 38,434 38,434 2011 2012 2013 2014 2015 1,313,713 1,313,713 2016 Totals 10,354,386,036 9,957,716 1,313,713 10,365,657,465
Average Annual (12-Year) $ Losses 862,865,503 829,810 109,476 863,804,789 Percent 99.9% 0.1% 0.0% 100.0%
The vast majority of losses from Severe Coastal Flooding over this period occurred in Region 2 in 2008. 99.9% of the dollar losses in 2008, both in Region 2 and 3, were caused by Hurricane Ike.
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Sample Event Description: Hurricane Ike Storm Surge
The following extract from the NCEI Storm Events database episode/event entries describes a Sever Coastal Flooding event that occurred September 12 and 13, 2008 with the landfall of Hurricane Ike.
Hurricane Ike caused wind damage and significant storm surge flooding across southeast Texas. Ike made landfall near Galveston, TX early in the morning on September 13th as a strong category 2 hurricane. Sustained hurricane force winds were confined to Jefferson County, Hardin County, western Orange County, southwestern Jasper County, and western Tyler County. The highest recorded winds were at Southeast Texas Regional Airport with sustained winds of 61kts (70 mph) and gusts of 83kts (96 mph). The lowest pressure reading also occurred at Southeast Texas Regional Airport, with a low of 982.4mb. No tornadoes were reported in southeast Texas.
Storm surge was a significant event:
Sabine Pass had its highest water level recorded during Ike, with a maximum of 14.24ft MLLW. Any home that was not elevated was destroyed. This storm surge almost topped the seawall around Port Arthur, but large waves did crash over the seawall, causing some flooding of homes within 3 blocks of the seawall.
In Orange County, Bridge City had nearly all of their homes flooded (over 3000), and this extended north to Rose City, and northeast to the city of Orange, where water topped the levee on the east side of town. Over 3000 homes were also flooded in Orange.
At least 100 homes were flooded in Port Arthur. The surge also backed up Hillebrandt and Taylor Bayou west of Port Arthur, causing widespread flooding in the Hillebrandt, Hamshire, and Fannett communities. The surge also backed up the Neches River in Beaumont, where some homes along the river flooded. In total, at least 4000 homes were flooded county-wide.
Maximum storm total rainfall was between 5 and 8 inches across Jefferson, Hardin, Orange, and southern Jasper counties. Only one fatality occurred during Ike. A 40 year old man was trying to drive back to his home in Port Neches. His truck was swept off Highway 73 near Rainbow Bridge by the large storm surge and waves. Total damages, however, were high. Loses are estimated to be at least 1.3 billion dollars across southeast Texas.
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County and Regional Dollar Losses
Map 3.4.2 shows total county losses (property plus crop losses) from Severe Coastal Flooding over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had these sorts of impacts -white represents zero dollar losses. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.4.2: Historical Severe Coastal Flooding Dollar Losses
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Map 3.4.3 shows Region 2 total county losses (property plus crop losses) from Severe Coastal Flooding. County colors indicate their losses relative to other counties within the region. Each color represents approximately 20 % of the region’s counties. With 35 counties in Region 2, 7 counties are within each 20% bracket. The inset table in this map reports the total dollar losses for the highest- loss counties. These counties are also labeled.
Map 3.4.3: Historical Severe Coastal Flooding Dollar Losses in Region 2
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Future Risks
Results of the hazard impact forecast for Severe Coastal Flooding are presented below along with a local assessment of those risks. Following this is a discussion more generalized risk and a summary of risk statewide.
County Dollar Loss Forecast Map 3.4.4 shows the county forecasts for 2019-2023 for Severe Coastal Flooding dollar losses. These illustrate likely locations of future losses.
Map 3.4.4: Severe Coastal Flooding Dollar Losses Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations as during the based period. Future Severe Coastal Flooding dollar losses will not necessarily be in the same places they were in the past, but a strong correlation is likely. The local risk assessment for Severe Coastal Flooding in Galveston County below supports this forecast. 83 CHAMPS ’17: A Hazard Assessment for Texas
Local Risk Assessment: Galveston County Galveston County had the highest Severe Coastal Floods impacts of any county in Texas over the base period and is forecast to have the highest impacts over the forecast period. The following was extracted from the Galveston County Hazard Mitigation Plan (February 2017) showing their estimation of hazard risk:
Flooding in coastal areas of Galveston County are defined by recurrence intervals and flood zones are determined. Coastal flood zones consider the velocity of wave action. Coastal flood results are provided for the five surge inundation zones, and Risk MAP VE zone results are provided in the coastal and inland flood section. Inland flooding is predominantly caused by coastal inundation from the Gulf of Mexico and the Galveston, East and West Bays.
The coastal flood inundation zone is an area of high potential for property damage and loss of life due to storm surge induced high‐velocity wave action.
Figure 6.1 depicts these zones. It is significant to note that Jamaica Beach is located on a barrier island. There are threats to this community that are not applicable to the majority of the other jurisdictions in Galveston County. Hurricane‐generated storm surge could very possibly damage surrounding infrastructure, including the bridge leading off of the barrier island. Damage to the bridge could isolate residents from the mainland and deprive residents of essential utility and emergency services.
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… Figures 6.2 graphically illustrate the flood zones listed above and provide an indication of where there is potential for damage to property and loss of life in the Galveston County study region. Much of the flooding is attributed to coastal and bay flooding.
… Based on the vulnerability assessment, a coastal flooding or storm surge event will have a greater impact on the area than an inland flood event. With a strong hurricane storm surge, the total value at risk is over $17 billion dollars compared to approximately $5 billion with an inland flooding event. Based on the relative exposure and history of previous occurrences, the potential severity and impact of a major flood event are substantial. A major event or storm surge could result in multiple fatalities, a complete shutdown of facilities for 30 or more days, leaving more than half of all property destroyed or substantially damaged.
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Regional Impact Forecast Regional forecasts for Severe Coastal Flooding impacts for 2019–2023 are shown in Table 3.4.3. These are the highest forecast losses from any hazard in the forecast period. Total expected statewide costs for Severe Coastal Floods in the forecast period are $5.6 billion. Though Region 2 is forecast to receive almost all of this damage, actual future losses may be more distributed.
Table 3.4.3: Severe Coastal Flooding Impact Forecast Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 Region 2 5,606,970,326 7 598.55 Region 3 5,173,604 1.96 Region 4 Region 5 Region 6 654,904 0.10 Total/St. 5,612,798,835 7 176.89
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 9,827,579 Region 2 100% 100% 9,367,616 Region 3 0% 2,640,570 Region 4 1,686,015 Region 5 1,488,783 Region 6 0% 6,719,781 Total/St. 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 1,122,559,767 1 35.38
The average annual losses from Severe Coastal Floods over the forecast period are expected to increase 30% (over the 12 year calculation for the base period). This increase is due to a combination of population growth, building exposure increases and weather pattern changes. This is the hazard with the highest expected increase based on changing weather patterns. This hazard is expected to increase in damage potential approximately 20% in 10 years.
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Risk Summary Severe Coastal Flooding risk in Texas is extreme. The average annual historical dollar losses when calculated over the 12 years that data was specifically collected on this hazard, they were $864 million. The forecast annual dollar losses for Severe Coastal Flooding are $1.1 billion. The total forecast dollar losses for the 5- year forecast period are $5.6 billion. Actual losses could be higher or lower due to the capriciousness of the storms that create them.
When considered together with the Hurricane TS/Ds, these two hazards caused approximately $28 billion in losses over the 21-year base period: $1.3 billion a year: more than twice as much as the second most expensive hazard, drought; and three times as much as the third most expensive hazard Hailstorms.
The forecast for Hurricane TS/Ds and Severe Coastal Flooding costs exceed these measures. They are expected to cause $11.1 billion in losses over the 5-year forecast: $2.2 billion a year. Over the forecast period, Hurricanes and Coastal Flooding are expected to cost almost three times more than the second most expensive hazard, drought; and four times more than the third most expensive hazard Hailstorms.
Aside from the associated Hurricane TS/D impacts, 22% of the statewide losses from all weather–related hazards in the 21-year base period came from Severe Coastal Flooding. The forecast is for 34% of all weather-related dollar losses in the next 5-years to come from Severe Coastal Flooding
All coastal counties in Texas are equally likely to be hit with coastal flooding. If these events hit the upper Texas Gulf coast, they will inundate larger areas however. The more populated and developed that areas are, the more damage, loss of life and injury that is likely to result. The upper Texas Gulf Coast is the most populated and developed of all the Texas coastal regions.
Hurricanes and the Severe Coastal Flooding that accompany them are capricious in their timing, strength and locations of impact. All areas along the coast need to mitigate for Severe Coastal Flooding and otherwise be ready to deal with the damages they create.
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3.5: RIVERINE FLOODING
Riverine Flooding is the weather-related hazard with the most specific and localized risk maps. Riverine Flood risks are calculated in Hydrologic and Hydraulic (H&H) studies. Hydrologic elements calculate how much water is expected in a given system (either coming into the system from contributing waterways or from precipitation within a catchment area) and hydraulic element calculate how that water can be expected to flow through the system (based on the capacity of different parts of the system to move water through). This engineering process produces estimates at various points along the waterway that, together make up expected water levels of various probabilities (or return periods).
H&H studies determine at what volumes waters will overflow the banks of the river systems in question and what the resultant inundation areas will be at given return periods, or percent chance of flooding. Federal regulation call for houses with their base floor elevation within 1 foot of the 100-year-floodplain (or 1 percent annual chance of flooding) to participate in the Nation Flood Insurance Program (NFIP) – a federally subsidized insurance program administered by FEMA in coordination with state and local governments. This program seeks to limit damages through regulation and also to help stabilize the real estate markets nationwide.
In order to carry-out its duties under NFIP, FEMA (through contractors) develops and maintains 1% change floodplains across the nation. Mapping is done on an area-by-area basis that is prioritized for high risk areas. The vast majority of Texas is covered by these studies.
Through local in the immediate impacts, riverine flooding damages are widely dispersed in Texas. This study concerns itself with the overall nature of that those damages. Over the base period of this study, Riverine Flooding killed and injured more people than any other weather-related hazard. The number-one cause of deaths from flooding is people driving their cars into water going over roads.
Dam and Levee Failure
One issue that contributes to the risk of flooding is the potential failure of dams and levees. A dam failure is defined as a systematic failure of the dam structure resulting in the uncontrolled release of water, often resulting in floods that could exceed the 100-year flood plain boundaries. A dam failure could cause mass fatalities, mass structural damage and/or a potentially cascading event if populated and/or industrial area are located near and downstream of the dam structure.
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There are currently 1,031 dams in Texas, including Federal dams, which are classified as high hazard, meaning if failure occurs, it is likely there will be loss of life. This classification does not necessarily mean that these dams are in need of repair -- these dams could be in excellent condition or they could be in poor condition. The term "high-hazard" reflects the dam's potential for doing damage downstream should it fail, which is termed “dam inundation”. In addition, there are 737 dams which are classified as significant hazard, meaning that there could possibly be loss of life if the dam should fail.
There is an increasing number of these high-hazard structures -- not because more high-hazard dams are being built, but because more development is occurring downstream. Owners of dams that were built as low hazard dams are finding that the hazard classification has changed due to the increase in population downstream of the dams.
Hazard Classification: Category Loss of Life Economic Loss Low None Expected Minimal Significant Possible, but not expected Appreciable High Expected Excessive
Levees have been constructed in Texas for over 100 years to protect farm and ranch land and populated areas from flood flows. There is no state levee safety program. An entity under the National Flood Insurance Program requirements is required to approve new levee construction, or modifications to existing levees; however, there is no state inspection program and limited owner maintenance. In addition, there is no database identifying and locating the levee systems in Texas. Any populated areas behind levees could be at risk during major flood events
In terms of loss of life and property to residents located close to dams, the area downstream at a lower elevation is most affected. This is referred to in mitigation planning as the inundation or impacted area. It is assumed that dam breaks happen at the time of maximum capacity and that the location of the released water would inundate a downstream area proportional to the maximum capacity of the dam.
Inundation maps require resources similar to floodplain mapping and are for most private dam owners are cost prohibitive and not produced.
89 CHAMPS ’17: A Hazard Assessment for Texas
The best location for major dams is the lowest portion of the watershed, combined with a narrow channel which reduces dam construction costs. In Texas, this combination of factors is best met where the drainage off the Llano uplift meets the coastal plains. Indeed, the highest concentration of major reservoirs occurs in this band. Refer to map on the left below.
High hazard dams occur where many reservoirs are located in the vicinity of dense populations. Overlaying population density on high dam concentration results in areas of high risk shown on the map to the right above.
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Historical Experience
The annual average dollar losses due to Flooding in Texas over the 21 year period 1996 thru 2016 was $246,886,388. This is the fifth most expensive weather- related hazard in Texas over that period. Table 3.5.1 below shows property losses, crop losses, deaths and injuries attributed to Flooding in Texas.
Table 3.5.1: Historical Riverine Flooding Impacts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 1,313,833,015 30,163,878 80 50 152.32 Region 2 391,497,037 2,884,436 52 6 48.77 Region 3 341,117,981 473,995,768 27 357 140.87 Region 4 323,319,967 6,895,726 9 9 213.90 Region 5 249,271,812 444,494,372 17 12 174.37 Region 6 1,584,251,693 22,888,461 169 6,550 277.48 Total/St. 4,203,291,505 981,322,641 354 6,984 151.61
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 31% 3% 23% 1% 8,625,547 Region 2 9% 0% 15% 0% 8,027,607 Region 3 8% 48% 8% 5% 2,421,457 Region 4 8% 1% 3% 0% 1,511,557 Region 5 6% 45% 5% 0% 1,429,523 Region 6 38% 2% 48% 94% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 200,156,738 46,729,650 17 333 7.22
All regions in Texas suffered losses in the hundreds of millions of dollars over this period. Region 6 and 1 both had total losses of over a billion dollars. Including crop losses, Region 3 and 5 had losses between $500 million and $1 billion. Regions 2 and 4’s losses were between 300 and 400 million. Region 6 leads in all categories. It had 31% of the statewide dollar losses, 47.7% of the deaths and 93.8% of the injuries from Flooding.
The Ann Per-Cap Prop Losses, times the 27.7 million estimated 2016 state population equals the $200 million annual average property losses statewide in the base period.
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Table 3.5.2 shows total dollar-losses by year for Riverine Flooding over the base period. With one exception, every region experienced losses due to riverine flooding in every year. The annual statewide totals for these losses went from a low of $956 thousand in 2011 to $1.8 billion in 2015 and averaged just under $250 million. Regions 1 and 6 had 57% of the statewide losses.
Table 3.5.2: Annual Dollar-Losses from Riverine Flooding
Region 1 Region 2 Region 3 Region 4 Region 5 Region 6 Totals 1996 1,363,118 4,342,743 84,301,250 6,456,880 4,510,658 2,859,029 103,833,678 1997 1,431,032 3,575,332 3,977,341 21,159,562 4,421,422 81,512,071 116,076,760 1998 2,821,106 2,481,703 66,614,796 367,332 16,163 883,164,347 955,465,447 1999 306,203 3,356,739 350,772 3,077,131 9,178,919 1,106,946 17,376,710 2000 5,243,407 21,870,716 481,221 1,842,842 14,408,941 2,472,865 46,319,992 2001 1,616,050 18,823,265 404,350 54,093 419,225 10,622,641 31,939,624 2002 127,803 17,507,863 3,421,431 13,679,060 83,939,489 5,092,214 123,767,860 2003 80,700 6,112,455 31,779,307 1,302,930 1,643,958 1,274,287 42,193,637 2004 43,437,110 11,117,925 5,678,774 11,796,232 1,308,440 7,500,699 80,839,180 2005 393,648 348,276 30,658 967,566 1,722,980 67,447 3,530,575 2006 946,834 17,534,827 2,768,032 238,900,065 665,279 784,078 261,599,115 2007 124,714,455 3,081,269 11,660,751 1,224,652 51,103,736 197,034,673 388,819,536 2008 3,009,046 11,448,835 379,496,815 16,891,813 33,140,659 233,604 444,220,772 2009 12,023,309 30,288,664 12,283 418,710 3,521,600 6,132,656 52,397,222 2010 31,281,050 3,853,303 111,987,387 524,351 32,493,373 28,534,650 208,674,114 2011 8,519 26,623 37,272 564,406 319,475 956,295 2012 1,622,050 10,613,727 16,997,616 3,916,390 903,342 997,221 35,050,346 2013 443,023 5,480,234 1,208,804 4,201,220 183,170 107,750,332 119,266,783 2014 5,920,211 228,673 1,618,926 1,901,842 101,556,296 612,154 111,838,102 2015 1,103,781,219 32,409,301 89,760,963 1,467,922 336,548,628 267,738,765 1,831,706,798 2016 3,427,000 189,879,000 2,525,000 65,100 11,515,500 1,330,000 208,741,600 Totals 1,343,996,893 394,381,473 815,113,749 330,215,693 693,766,184 1,607,140,154 5,184,614,146
Average Annual $ Losses 63,999,852 18,780,070 38,814,940 15,724,557 33,036,485 76,530,484 246,886,388 Percent 25.9% 7.6% 15.7% 6.4% 13.4% 31.0% 100.0%
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Sample Event Description: The Great October Flood
The following is a description of “The Great October Flood” (episode #2150299) from NCEI Storm Events Database. This episode occurred from October 16 through 21, 1998 and had its primary impacts in Region 6 (paragraph returns inserted)
In advance of a very slow-moving upper level trough of low pressure over West Texas, a cold front drifted slowly southeastward into West Central Texas during the evening of Friday, October 16th. Deep moisture was in place across South Central Texas as the two systems approached, being fed at the mid and upper levels by two nearly stationary hurricanes, Madeline near the tip of Baja Mexico, and Lester, anchored just off Acapulco, Mexico, and in the low levels by a strong flow from the Gulf of Mexico. A very moisture-rich environment was in place across South Central Texas as the event developed. Near 3 am CST, with the cold front still west of San Angelo, scattered showers and thunderstorms began to break out over Bexar County beneath the mid and upper level moisture plume. They quickly became widespread as a low level rain-cooled boundary formed along the south and east edge of the county. It was upon this boundary that subsequent showers and thunderstorms continued to form. By 6 am CST, rainfall of up to 4 inches had been reported in Western Bexar County, with amounts approaching 4 inches in Western Comal County. By 8 am CST that morning, heavy rain continued over Bexar County, and had spread northward across Comal County into Hays, Travis and Williamson Counties. Amounts at this time were approaching 8 inches in Bexar and Comal Counties and 4 inches in Hays and Travis Counties. The heavy rain continued through the morning period. Shortly before noon on Saturday, heavy rain began to spread eastward into Guadalupe, Caldwell, Bastrop and Lee Counties. Through the midafternoon, moderate to heavy rain continued between San Antonio and Austin, with widespread heavy rain over Comal, Hays, Caldwell, Guadalupe and Gonzales Counties. By 5 pm CST, the strongest low level flow had also shifted eastward, focusing the heaviest rainfall through the evening period over the area from LaGrange to Gonzales to Karnes City to Cuero and Hallettsville. By midnight, heavy rain had exited the Cuero-Hallettsville area, and moderate rain had again broken out over Bexar and Comal Counties. The activity spread westward through the early morning hours on Sunday to Hondo and Uvalde and northwestward into the Hill Country. At the same time, moderate to heavy rain also redeveloped along and north of a line from San Antonio to Gonzales to LaGrange. By late Sunday morning, the cold front moved through South Central Texas, and had slowed and stalled as it approached the Lower Texas Coast. Spotty heavy rainfall continued in the wake of the front between San Antonio, Burnet and Bastrop as another weak upper level disturbance in the southwesterly flow aloft approached. Heavy rain also developed along the front, just north of Laredo and along the coastal plains from Corpus Christi to Victoria. Even though rainfall amounts in the San Antonio to New Braunfels to San Marcos to Austin corridor were generally below 2 inches on Sunday, soils remained saturated from the
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previous day's deluge and periods of flash flooding were reported through the mid-morning. By Sunday afternoon, rain had diminished in the San Antonio to Austin corridor, while clouds, rain and frequent showers continued east of the area. Thereafter, rainfall was generally along and east of a LaGrange-Gonzales-Karnes City line, where an additional 3 to 5 inches of rain fell on Sunday and 2 to 4 inches fell on Monday. Only scattered light rain was reported on Tuesday and Wednesday, the 20th and 21st of October. All rivers, creeks and streams along and east of a San Antonio to Austin line remained at or above flood stage from Saturday, October 17th through Sunday, October 18th, with a majority continuing to flood through Monday, October 19th. On Tuesday, October 20th and Wednesday, October 21st, flooding was confined to rivers, streams and creeks along and east of a LaGrange-Gonzales-Karnes City line. This event broke rainfall records across South Central Texas, producing 18 floods of record in South Central Texas streams. October became the wettest of any month in climate records for San Antonio since 1885. October 17th became the wettest day and wettest 24-hour period in San Antonio climatic records, nearly doubling both previous records. Rivers across the area reached or exceeded record stage heights, resulting in widespread flooding in the flood plains of streams, creeks and rivers. Rainfall amounts on October 17 and 18th from northern Bexar County to southeast Kendall County, most of Comal County and southern Hays County ranged from 15 to 22 inches. Damage and destruction to livestock and agriculture, roads and bridges and both public and property and buildings significantly exceeded that of previous flooding. Thousands to tens of thousands of livestock were killed, as nearly 3000 homes were destroyed and another 8000 or so homes were damaged. Nearly 1000 mobile homes were destroyed and another 3000 were damaged. Twenty-five people drowned as a direct result of the flooding in October in South Central Texas. All nine deaths in Bexar County on Saturday, as well as the two on Sunday, were associated with driving vehicles into flooded waters. Four of the six Caldwell County deaths, two of the three Guadalupe County deaths, and all of the four deaths in Comal, Travis and Uvalde County were associated with vehicles as well. Two deaths in Caldwell County and one in Guadalupe County occurred as residents were swept by flood waters from their homes. In addition, one man in Comal County suffered a heart attack and died waiting to be rescued and another died of a heart attack while being rescued. A third man in Guadalupe County accidently touched a live wire while in his boat. He was severely shocked and died from drowning as a result of the shock.
The NCEI database shows $205 million dollars of total damage from this episode. 99.9 % of that damage was in Region 6. It also reported 4,320 injuries (direct or indirect), all in Region 6, and 25 deaths, 24 of which were in Region 6 and one in Region 3 (the Uvalde death mentioned above). The 4,320 injuries constitute 62% of the total number of injuries from floods statewide over the 21-year reporting period and 30% of the injuries from all weather-related hazards over that time.
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County and Regional Dollar Losses
Map 3.5.1 shows total county losses (property plus crop losses) from Flooding over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had these sorts of impacts -white represents zero dollar losses. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.5.1: Historical Riverine Flooding Dollar Losses
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Map 3.5.2 shows Region 6 total county losses (property plus crop losses) from Riverine Flooding. County colors indicate their losses relative to other counties within the region. Each color represents approximately 20 % of the region’s counties. With 43 counties in Region 6, 8 or 9 counties are within each 20% bracket. The inset table in this map reports the total dollar losses for the highest- loss counties. These counties are also labeled.
Map 3.5.2: Historical Riverine Flooding Dollar Losses in Region 6
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Future Risks
Results of the hazard impact forecast for Riverine Flooding are presented below along with a local assessment of those risks. Following this is a discussion more generalized risk and a summary of risk statewide.
County Dollar Loss Forecast Map 3.5.3 shows the county forecasts for 2019-2023 for Riverine Flooding dollar losses. These illustrate likely locations of future losses.
Map 3.5.3: Riverine Flooding Dollar Losses Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations as during the based period. Future Riverine Flood dollar losses will not necessarily be in the same places they were in the past, but a strong correlation is likely.
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Local Risk Assessment: City of Wimberley Hays County had the second highest Riverine Floods impacts of any county in Texas over the base period. The following are excerpts from appendix J of Hays County Hazard Mitigation Plan (from 2011) describing riverine flooding risks for the City of Wimberley. It is one of thousands in Texas that express flood risk at the local level.
The City of Wimberley is vulnerable to shallow and riverine flooding. The 2008 Wimberley Comprehensive Plan indicates that the city experiences periodic heavy rains that produce very rapid run-off. When this occurs, normally dry creek beds can suddenly turn into raging torrents, over-feeding rivers and causing them to overflow their normal banks.
Typically the highest flow rates occur during spring rainfall events. Flows in the creeks and streams in the Wimberley region generally are erratic in response to rainfall events. The normal flow in the Blanco River and Cypress Creek is characterized by shallow, fast moving reaches with some rapids and some relatively deep, sluggish pool areas. Other smaller creeks and streams that do not experience spring flows typically are dry, except during heavy rainfall events.
… According to the Hays County GIS, a total of 1.05 square miles of the City (9.0 square miles total) is located within the 100-year floodplain. Wimberley has a total of 760 parcels that have some exposure to the 100-year floodplain. Various floodplain maps for the city are presented within this subsection.
Flood severity is measured in various ways, including frequency, depth, velocity, duration and contamination, among others. The frequency of flooding is often the most common for judging severity. A USGS gaging station along the Blanco River at Wimberley indicates the greatest flood on record occurred in May of 1929. The peak flow from this event was 113,000 cubic feet per second (cfs). To provide some perspective as to the velocity, the mean daily stream flow at this gage is roughly only 130 cfs. More recently, the December 1991 flood along the Blanco River reached a peak flow of 32,900 cfs at the Wimberley gaging station.
The impacts on life and property from flooding can be significant. Property owners that have experienced repetitive flooding in the past must cope with the disruptions and costly repairs associated with flooding.
Based on a review of open source documents Wimberley has recently experienced flood events in 1991, 1997, 1998, 2001, 2002, 2007, and 2009. With seven events over the past 19 years, the City is likely to be impacted by floods slightly less than every three years, an annual statistical probability of about 33 percent.
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Regional Impact Forecast Regional forecasts for Riverine Flooding impacts for the 5-year period 2019–2023 are shown in Table 3.5.3. Total statewide costs for Riverine Flooding in the forecast period are $1.4 billion. This hazard is forecast to remain the 5th most costly. Region 6 can expect $450 million in losses, 40% of the statewide total. Region 1 can expect almost $350 million: 30 % of the total. The number of deaths and injuries from riverine flooding in the base period was higher than any other hazard. In the forecast period, Extreme Heat is forecast to replace Riverine Flooding as the number one killer. Still almost 100 people (20 a year) are expected to perish due to Riverine Flooding.
Table 3.5.3: Riverine Flooding Impact Forecasts Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 343,763,513 7,609,982 21 13 34.98 Region 2 102,585,521 727,708 14 2 10.95 Region 3 89,824,911 119,583,409 7 92 34.02 Region 4 87,209,363 1,739,708 2 2 51.73 Region 5 64,108,044 112,140,563 4 3 43.06 Region 6 451,918,890 5,774,482 47 1,806 67.25 Total/St. 1,139,410,241 247,575,854 96 1,918 35.91
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 30% 3% 22% 1% 9,827,579 Region 2 9% 0% 15% 0% 9,367,616 Region 3 8% 48% 7% 5% 2,640,570 Region 4 8% 1% 3% 0% 1,686,015 Region 5 6% 45% 5% 0% 1,488,783 Region 6 40% 2% 49% 94% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 227,882,048 49,515,171 19 384 7.18
The Ann Per-Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $228 million annual average statewide property losses forecast. This is an increase of 12% (over the base period). This increase is due to a combination of population and building exposure increases and expected increasing Riverine Flood- related damage due to weather pattern changes.
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Risk Summary With expected dollar losses over $1.4 billion over the forecast period ($280 million a year) and 400 people a year either killed or injured because of it, Riverine Flooding is a persistent and dangerous hazard in Texas. There were 3,870 reports of Riverine Flooding impacts over the base period (22 times as many as for Hurricane TS/Ds). These provide a good basis for determining both the magnitude and the locations of future losses. The 3,870 data points that went into the model help produce a reliable depiction of how much damage there is likely to be in the future, and where that damage will likely occur.
Map 3.5.4 shows the Riverine Flooding dollar loss forecast for 2019 – 2023 in Region 6 – the most at-risk region. This map, together with the statewide forecast map (Map 3.5.3) and the regional forecast table (Table 3.5.3) provide the best picture of expected future risks.
Map 3.5.4: Forecast Riverine Flooding Dollar Losses in Region 6
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3.6: TORNADOS
The following Description of Tornados comes from Taking Shelter from the Storm (FEMA P-320, 4th Edition, Dec. 2014:
A tornado is a violently rotating column of air with wind speeds that can be significantly higher than design wind speeds in modern building codes. Although tornadoes typically occur in the spring and summer months, they can occur at any time in any part of the country. In some cases, hurricanes spawn tornadoes.
The severity of a tornado is categorized by the Enhanced Fujita Scale (EF Scale). As of February 2007, the EF Scale (see Figure 2-1) was adopted by the National Oceanic and Atmospheric Administration (NOAA) to replace the Fujita Scale (F Scale). The EF Scale is designed to be similar to the F Scale, but has been revised to have a greater number of Damage Indicators, which are used to characterize the degree of damage experienced by buildings during a tornado.
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The risk and frequency of tornadoes varies across the country and within each State. Comparing the numbers of tornadoes recorded in different areas of the country can give you a better understanding of potential tornado activity in those areas. Figure 2-2 shows the general locations of recorded EF3, EF4, and EF5 tornadoes in the United States between 1950 and 2013 (NOAA, 2014a). While this map presents a reasonable portrayal of tornado activity in the United States since 1950, it should not be assumed that locations that do not have a tornado track marked have never had a tornado or will never experience one.
Note: EF 0, 1 and 2 tornados are not presented on this map.
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Historical Experience
In 2016 dollars, the annual average total dollar losses due to Tornados in Texas over the base period was $108,896,168. This was the sixth most expensive weather-related hazard over that period. Table 3.6.1 below shows the property and crop losses as well as deaths and injuries directly or indirectly attributed to Tornados.
Table 3.6.1: Historical Tornado Impacts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 1,471,920,689 277,786 31 1,003 170.65 Region 2 169,160,963 5,417,106 6 208 21.07 Region 3 228,385,440 138,818 8 47 94.32 Region 4 17,273,139 1,497,574 1 16 11.43 Region 5 50,189,690 88,811,174 5 74 35.11 Region 6 252,805,237 941,914 33 143 44.28 Total/St. 2,189,735,158 97,084,372 84 1,491 78.98
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 67% 0% 37% 67% 8,625,547 Region 2 8% 6% 7% 14% 8,027,607 Region 3 10% 0% 10% 3% 2,421,457 Region 4 1% 2% 1% 1% 1,511,557 Region 5 2% 91% 6% 5% 1,429,523 Region 6 12% 1% 39% 10% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 104,273,103 4,623,065 4 71 3.76
All regions suffered losses from Tornados over this period. Region 1’s property losses were the highest. At 1.47 billion they were more than two-thirds of the total statewide amount of 2.19 billion. Region 5’s crop losses of almost $89 million were 91 percent of the crop losses in the state. While most region’s losses were 90% property losses, Region 5’s losses were only 36% from property damage and 64% from crop losses. Region 6 lost two more people than Region 1, and had the highest share of the statewide death total.
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Table 3.6.2 shows total dollar-losses by year for Tornados over the base period. With three exceptions, every region experienced losses due to tornados in every year. The annual statewide totals for these losses went from a low of $5.7 million in 2014 to $755 million in 2013 and averaged just under $109 million. Region 1 had $70 million (64%) of those average annual losses.
Table 3.6.2: Annual Dollar-Losses from Tornados
Region 1 Region 2 Region 3 Region 4 Region 5 Region 6 Totals 1996 7,994,017 2,495,745 30,529 1,526,450 2,193,507 286,971 14,527,219 1997 693,879 21,786,289 186,527 1,410,139 3,492,146 188,817,026 216,386,006 1998 1,285,660 17,852,301 29,387 2,657,275 1,420,838 897,758 24,143,219 1999 218,617,786 8,417,010 73,315 1,674,777 1,756,719 2,106,049 232,645,656 2000 12,296,282 7,253,150 180,807 773,298 1,589,016 5,101,541 27,194,094 2001 8,898,419 10,747,072 175,804 2,846,681 32,061,352 54,729,328 2002 485,922 10,655,685 113,206,684 53,252 5,833,069 8,034,367 138,268,979 2003 15,931,958 11,705,262 1,952,446 13,016 2,238,805 204,356 32,045,843 2004 787,345 10,707,773 63,393 332,181 5,020,752 384,164 17,295,608 2005 13,490 643,817 263,659 1,015,393 87,911,095 171,685 90,019,139 2006 7,183,813 5,284,208 1,793,874 184,140 7,401,215 6,693,169 28,540,419 2007 3,920,038 189,475 92,871,238 86,650 11,209,596 1,397,952 109,674,949 2008 52,758,968 256,964 103,453 7,186,112 1,532,888 1,490,618 63,329,003 2009 5,229,367 34,508,100 66,994 243,409 1,710,556 1,175,728 42,934,154 2010 7,473,806 527,098 2,043,601 136,167 536,980 10,717,652 2011 2,887,526 611,264 5,888,995 106,492 21,299 1,363,096 10,878,672 2012 747,843,965 3,249,316 2,933,250 1,049,377 292,073 119,960 755,487,941 2013 275,990,343 755,505 25,697 925,106 167,547 277,864,198 2014 3,151,847 323,784 1,922,475 45,532 506 212,484 5,656,628 2015 94,750,044 18,609,251 1,162,130 5,053 768,017 3,001,328 118,295,823 2016 4,004,000 7,999,000 3,550,000 272,000 300,000 60,000 16,185,000 Totals 1,472,198,475 174,578,069 228,524,258 18,770,713 139,000,864 253,747,151 2,286,819,530
Average Annual $ Losses 70,104,689 8,313,241 10,882,108 893,843 6,619,089 12,083,198 108,896,168 Percent 64.4% 7.6% 10.0% 0.8% 6.1% 11.1% 100.0%
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Sample Event Description: April 3rd 2012 Tornado in Dallas County
The following are the episode and event narratives for a $417 Million dollar Tornado event that occurred on April 3rd 2012 in Dallas County. They come from the NCEI Storm Events Database.
Episode description: A historic North Texas tornado outbreak occurred on April 3rd, with 17 tornadoes developing from the DFW Metroplex east to Hopkins County. An EF-3 tornado tore through the town of Forney, heavily damaging homes in the Diamond Creek subdivision. Three EF-2 tornadoes damaged parts of Arlington and Kennedale in Tarrant County; Red Oak, Lancaster, and Dallas in Ellis and Dallas counties; and Royse City in Rockwall and Hunt counties. An EF-1 tornado caused damage near Joshua in Johnson County, and the remaining 12 tornadoes were rated EF-0s.
In addition to the tornadoes, large hail damaged many parts of the DFW Metroplex. Approximately 110 airplanes at DFW International Airport were damaged by the hail and taken out of service until repaired. No fatalities occurred and only 29 people were injured. Of the 29 injuries, only 3 were considered serious but everyone made a full recovery.
The environmental set-up on this day consisted of a cut-off low over New Mexico with a front draped north-to-south across the western counties of the CWA. By mid to late morning, strong and severe storms developed along the front as a lobe of energy rotated into west Texas and forcing from this energy overspread the front. The atmosphere was already unstable and uncapped by this time.
In addition, a Mesoscale Convective System in Oklahoma sent an outflow boundary south across the Red River. This outflow boundary moved south of the DFW Metroplex by the late morning hours, and isolated storms began to develop south of the outflow boundary but east of the front. As these storms moved north and crossed the outflow boundary, the low level rotation increased and the storms quickly became tornadic. All of the tornadic storms were tied to this outflow boundary as it retreated north as a warm front.
(Continued below)
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Event description: … The tornado crossed into Dallas County near I-35E at the Ellis/Dallas County line. Light damage was noted as the tornado crossed into the county but then the tornado moved into the city of Lancaster and struck the Portofino Apartments where it damaged the roofs of two buildings and tore the roof off another building. Cars were moved in the parking lots, and the windows were blown out in one car. The tornado did significant damage to homes just northeast of the apartment complex, beginning on Sunny Meadow Dr.
However, the most significant damage occurred near the intersections of Wintergreen Rd, Telephone Rd, and North Dallas Ave. Many homes in this area were heavily damaged or destroyed. Some cars were pushed into fences, many trees and tree branches were knocked down, an RV was crumpled, and some fence boards penetrated homes. The Cedar Valley Christian Academy also sustained heavy damage when it lost an entire wall.
The tornado continued northeast crossing Interstate 20 near Dynasty Drive. The tornado hit a trucking company along the interstate, lofting several empty semis into the air. About 50 semitrailers were damaged or destroyed. The tornado damaged a few additional trees northeast of the trucking company and caused some minor roof damage in the Stagecoach neighborhood.
The damage track ended near Palm Island St and Tioga St. In the city of Lancaster, 64 homes were destroyed, 51 sustained major damage, and another 58 sustained minor damage. An additional two homes were destroyed in the Dallas city limits. One home was destroyed when one of the semis from the trucking company was thrown into the house.
The path length of the tornado in Dallas County was approximately 9.4 miles long but the total length of the tornado was 13.7 miles. Maximum estimated winds were 130 mph with a maximum width of 200 yards. Ten people in the city of Lancaster were injured, and two people sustained serious injuries.
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County and Regional Dollar Losses
Map 3.6.1 shows total county losses (property plus crop losses) from Tornados over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had these sorts of impacts -white represents zero dollar losses. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.6.1: Historical Tornado Dollar Losses
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Map 3.6.2 shows Region 1’s total county losses (property plus crop losses) from Tornados. County colors indicate their losses relative to other counties within the region. Each color represents approximately 20 % of the region’s counties. With 36 counties in Region 1, 7 counties are within each 20% bracket. The inset table in this map reports the total dollar losses for the highest-loss counties. These counties are also labeled.
Map 3.6.2: Historical Tornado Dollar Losses in Region 1
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Future Risks
Results of the hazard impact forecast for Tornados are presented below along with a local assessment of those risks. Following this is a discussion more generalized risk and a summary of Tornado risks statewide.
County Dollar Loss Forecast Map 3.6.3 shows the county forecasts for 2019-2023 for Tornado dollar losses. These illustrate likely locations of future losses.
Map 3.6.3: Tornado Dollar Losses Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations as during the based period. Future Tornados dollar losses will not necessarily be in the same places they were in the past, but a strong correlation is likely. The local risk assessment information on Tornados is from Dallas County.
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Local Risk Assessment: City of Dallas Dallas County had the highest Tornados impacts of any county in Texas over the base period. The following is an extract from the Dallas County Hazard Mitigation Plan (from November 2015) describing Tornado risks for the Dallas County:
With an average of 139 (1953-2004) tornadoes touching down each year, Texas ranks first in tornado occurrences. Historically, Dallas County has had several tornadoes with the most recent occurring in April 2012.
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Table 5.10 below depicts historical tornado occurrences, magnitude and impacts of the hazard in Dallas County between 2000 and 2012.
Tornados in Dallas County have the ability to occur with little to no warning and follow no predictable patterns. There are many developments that are composed of modular or mobile structures that are more susceptible to the damaging effects of tornados and offer little to no protection.
The entirety of Dallas County is equally exposed to the damage risks associated with tornadoes. Typically, incidents are fairly localized and damages associated with individual events are relatively limited.
The probability of tornadoes recurring in Dallas County is high. May is the most active month for tornadoes in Texas, followed by April. Dallas/Fort Worth and the surrounding area is the area that sees the most tornadoes in Texas, and their most active month is May. Tornado season ends when the cold fronts stop coming into the state, usually by the end of May in the southern part, and the end of June in Northern Texas.
Dallas County and participating jurisdictions experienced 15 tornado events ranging from EF0 to EF2, during the time period analyzed for this plan (01/01/2002-06/30/2013). It can be expected that any future tornado events will be similar in magnitude.
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Regional Impact Forecast Regional forecasts for Tornado impacts for the 5-year period 2019–2023 are shown in Table 3.5.3. Total statewide costs for Tornados in the forecast period are $582 million. Region 1 can expect $370 Million of those losses, 67% of the total. This hazards remain the 6th most expensive in the state.
Table 3.6.3: Tornado Impact Forecast
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 374,502,330 66,140 8 257 38.11 Region 2 42,755,123 1,289,787 1 54 4.56 Region 3 58,887,286 33,052 2 12 22.30 Region 4 4,375,771 356,565 0 4 2.60 Region 5 11,953,924 21,145,518 1 18 8.03 Region 6 68,217,871 224,265 9 37 10.15 Total/St. 560,692,305 23,115,327 22 382 17.67
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 67% 0% 36% 67% 9,827,579 Region 2 8% 6% 7% 14% 9,367,616 Region 3 11% 0% 10% 3% 2,640,570 Region 4 1% 2% 1% 1% 1,686,015 Region 5 2% 91% 5% 5% 1,488,783 Region 6 12% 1% 41% 10% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 112,138,461 4,623,065 4 76 3.53
The Ann Per-Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $113 million annual average statewide property losses expected in the forecast period. This is an increase of 7.5% over the base period annual average. This increase is due to population growth and building exposure increases in the impacted areas. There are no expected changes to tornado damage due to weather pattern changes. Tornados are not expected to become more frequent or more damaging.
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Risk Summary With expected dollar losses over $582 million over the forecast period ($116 million a year) and 80 people a year either killed or injured because of them, Tornados are a persistent and dangerous hazard in Texas. There were 1,365 reports of Riverine Flooding impacts over the base period (9 times as many as for Hurricane TS/Ds). These provide a good basis for determining both the magnitude and the locations of future losses. The 1,365 data points that went into the model help produce a reliable depiction of how much damage there is likely to be in the future, and where that damage will likely occur.
Map 3.6.4 shows the Tornado dollar loss forecast for 2019 – 2023 in Region 1 – the most at-risk region. This map, together with the statewide forecast map (Map 3.6.3) and the regional forecast table (Table 3.6.3) provide the best picture of expected future risks. However, tornadoes are highly localized events, and there the chance that an F4 could go through downtown Dallas or Fort Worth and produce much higher losses. It is best to think of this forecast as being a “best estimate” and to consider the risk for tornados more at a regional than a county scale.
Map 3.6.4: Forecast Tornado Dollar Losses in Region 1
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3.7: SEVERE THUNDERSTORM WIND
Severe wind can occur alone, as in straight-line wind events (derechos), or can accompany other natural hazards, including hurricanes and severe thunderstorms. We analyze winds that occur with severe thunderstorms in this chapter. Wind hazards related to hurricanes are considered in Section 3.1. Severe Thunderstorm Winds pose a threat to lives, property, and vital utilities primarily due to the effects of flying debris, downed trees and interactions with power lines. Severe winds will typically cause the greatest damage to structures of light construction, particularly manufactured homes.
Generally the windstorm risk is greatest in the northern regions (regions 5 and 1) Region 5, the Texas Panhandle and just south of there is the area of Texas most vulnerable to windstorms as there are not many trees there to provide a natural wind break or barrier. However, the population density in these areas is low. In Region 1 where the population density is very high, the risk of occurrence is slightly less but still substantial. Regions 2 and 6 both have slightly higher dollar losses from this hazard then does Region 1.
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The generally accepted extent scale for wind events is the Beaufort Wind Scale. The following table lists categories, measurement, and classification and appearance descriptions.
Beaufort Wind Scale Developed in 1805 by Sir Francis Beaufort, U.K. Royal Navy
Appearance of Wind Effects Wind WMO Force (Knots) Classification On the Water On Land
Less 0 Calm Sea surface smooth and mirror-like Calm, smoke rises vertically than 1 Smoke drift indicates wind 1 1-3 Light Air Scaly ripples, no foam crests direction, still wind vanes Small wavelets, crests glassy, no Wind felt on face, leaves 2 4-6 Light Breeze breaking rustle, vanes begin to move Leaves and small twigs Large wavelets, crests begin to 3 7-10 Gentle Breeze constantly moving, light flags break, scattered whitecaps extended Dust, leaves, and loose paper Moderate Small waves 1-4 ft. becoming 4 11-16 lifted, small tree branches Breeze longer, numerous whitecaps move Moderate waves 4-8 ft taking longer Small trees in leaf begin to 5 17-21 Fresh Breeze form, many whitecaps, some spray sway Larger waves 8-13 ft, whitecaps Larger tree branches moving, 6 22-27 Strong Breeze common, more spray whistling in wires Whole trees moving, Sea heaps up, waves 13-19 ft, white 7 28-33 Near Gale resistance felt walking against foam streaks off breakers wind Moderately high (18-25 ft) waves of greater length, edges of crests begin Twigs breaking off trees, 8 34-40 Gale to break into spindrift, foam blown generally impedes progress in streaks High waves (23-32 ft), sea begins to Slight structural damage 9 41-47 Strong Gale roll, dense streaks of foam, spray occurs, slate blows off roofs may reduce visibility Very high waves (29-41 ft) with Seldom experienced on land, overhanging crests, sea white with trees broken or uprooted, 10 48-55 Storm densely blown foam, heavy rolling, "considerable structural lowered visibility damage" Exceptionally high (37-52 ft) waves, 11 56-63 Violent Storm foam patches cover sea, visibility
more reduced Air filled with foam, waves over 45 12 64+ Hurricane ft, sea completely white with driving
spray, visibility greatly reduced Source: www.spc.noaa.gov/faq/tornado/beaufort.html
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This map shows wind risk zones for the entire U.S. based on the highest expected wind speeds for 3-second gusts thirty-three feet above grade. It takes into account all wind hazards including severe thunderstorms, tornados and hurricanes. Zones are associated with the typical highest wind speeds for that region. It also reveals special wind hazard-prone areas. These wind speeds correlate to "design specifications of a shelter or safe room. Most of Texas needs to design for 160 to 200 mph wind, the rest for 250.
Source: FEMA and the American Society of Civil Engineers (ASCE)
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The image to the right shows expected peak wind speed (at least 3 second durations) for weather stations in a 50 year period. On the Texas coast there are 4 white spots indicating greater than 100 miles per hour winds. Most of the state can expect to see 80 to 90 mph winds at least once in 50 years.
The image to the left shows significant wind hazard risk zones for the entire U.S. expressed in the estimated “number of significant wind days” per year based on data collected between 1980 and 1994. Significant wind days are defined as those with winds greater than 65 knots or 74 mph.
Source: NOAA’s National Severe Storm Laboratory (NSSL), Severe Thunderstorms Climatology
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Historical Experience
In 2016 dollars, the annual average dollar losses due to Severe Thunderstorm Winds in Texas over the 21 year period 1996 thru 2016 was $70,108,536. This is the seventh most expensive weather-related hazard in Texas over that period. Table 3.7.1 shows property losses, crop losses, deaths and injuries directly or indirectly attributed to Severe Thunderstorm Winds. All Regions suffered losses from Severe Thunderstorm Winds over this period. Region 5 had total losses of $700 million, almost half of the total state losses of $1.47 billion. Region 2 was second with $258 million total losses and Region 6 was third with $182 million. Region 1 is fourth in dollar losses, but first in terms of deaths and injuries.
Table 3.7.1: Historical Severe Thunderstorm Wind Impacts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 146,001,024 132,485 18 126 16.93 Region 2 185,217,207 73,084,644 14 85 23.07 Region 3 107,525,279 1,465,743 14 44.41 Region 4 73,352,276 2,616,133 4 30 48.53 Region 5 650,527,235 48,660,374 11 95 455.07 Region 6 180,726,508 2,970,368 1 83 31.65 Total/St. 1,343,349,529 128,929,747 48 433 48.45
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 11% 0% 38% 29% 8,625,547 Region 2 14% 57% 29% 20% 8,027,607 Region 3 8% 1% 3% 2,421,457 Region 4 5% 2% 8% 7% 1,511,557 Region 5 48% 38% 23% 22% 1,429,523 Region 6 13% 2% 2% 19% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 63,969,025 6,139,512 2 21 2.31
The Per-Cap Prop Losses for Region 5 over the period are almost ten times those of other regions. The Ann Per-Cap Prop Losses, times the 27.7 million estimated 2016 state population equals the $64 million annual average property losses statewide.
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Table 3.7.2 shows total dollar-losses (property plus crop losses) by year for Severe Thunderstorm Winds over the base period. Without exception, every region experienced losses due to Severe Thunderstorm Winds in every year. The annual statewide totals for these losses went from a low of $10.8 million in 2005 to a high of $457 million in 2013 and averaged just over $70 million. Region 5 had $33 million (47.5%) of those average annual losses.
Table 3.7.2: Annual Dollar-Losses from Severe Thunderstorm Wind
Region 1 Region 2 Region 3 Region 4 Region 5 Region 6 Totals 1996 21,869,438 5,565,404 91,586 35,554,067 8,672,616 3,454,336 75,207,447 1997 24,155,907 3,121,692 553,607 3,505,949 14,740,460 3,035,153 49,112,768 1998 3,684,351 161,014,530 418,760 2,475,818 9,688,343 19,586,851 196,868,653 1999 3,379,978 6,442,796 8,572,263 4,521,466 18,282,979 2,526,406 43,725,888 2000 1,854,662 18,926,317 7,197,516 561,193 4,141,043 3,059,804 35,740,535 2001 2,722,265 37,384,177 1,534,906 2,388,236 18,779,317 9,678,715 72,487,616 2002 2,482,864 5,199,346 1,264,733 5,536,190 29,472,258 10,810,131 54,765,522 2003 6,669,548 643,007 43,255,783 2,009,845 7,070,517 32,113,832 91,762,532 2004 5,155,143 3,560,808 485,594 1,602,583 11,128,706 2,787,404 24,720,238 2005 2,818,089 1,965,184 522,412 1,714,396 2,633,215 1,109,820 10,763,116 2006 3,515,285 1,129,788 4,781,686 855,358 7,166,357 8,825,627 26,274,101 2007 5,966,133 1,774,597 3,605,788 6,667,417 8,835,048 3,152,901 30,001,884 2008 14,994,153 1,106,280 1,605,192 579,559 24,508,195 58,398,279 101,191,658 2009 17,710,300 1,920,759 1,296,880 3,756,859 14,725,353 13,542,377 52,952,528 2010 4,506,577 623,180 3,026,967 505,681 4,522,166 1,355,075 14,539,646 2011 11,397,082 1,876,930 2,691,159 50,584 31,530,095 1,946,674 49,492,524 2012 4,701,861 2,562,948 2,534,259 292,596 9,685,253 1,020,381 20,797,298 2013 2,034,718 906,348 400,877 1,854,632 451,473,845 411,877 457,082,297 2014 1,915,898 487,802 1,127,176 415,813 15,877,023 703,220 20,526,932 2015 2,707,257 1,767,958 5,717,178 198,067 3,403,320 6,037,013 19,830,793 2016 1,892,000 322,000 18,306,700 922,100 2,851,500 141,000 24,435,300 Totals 146,133,509 258,301,851 108,991,022 75,968,409 699,187,609 183,696,876 1,472,279,276
Average Annual $ Losses 6,958,739 12,300,088 5,190,049 3,617,543 33,294,648 8,747,470 70,108,537 Percent 9.9% 17.5% 7.4% 5.2% 47.5% 12.5% 100.0%
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County and Regional Dollar Losses
Map 3.7.1 shows total county losses (property plus crop losses) from Severe Thunderstorm Winds over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had Severe Thunderstorm Wind dollar losses. 2 of the 254 counties in Texas were speared these losses, they are shown in white. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.7.1: Historical Severe Thunderstorm Wind Dollar Losses
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Future Risks
Results of the hazard impact forecast for Severe Thunderstorm Winds are presented below. Following this is a discussion more generalized risk and a summary of Severe Thunderstorm Wind risk statewide.
County Dollar Loss Forecast Map 3.7.2 shows county forecast losses for 2019-2023 from Severe Thunderstorm Wind.
Map 3.7.2: Severe Thunderstorm Wind Dollar Losses Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations as during the based period. The Risk Summary below, places this forecast in the broader context of the overall Severe Thunderstorm Winds risk in Texas.
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Regional Impact Forecast Regional forecasts for Severe Thunderstorm Wind impacts for the 5-year period 2019–2023 are shown in Table 3.7.3. Total statewide losses for Severe Thunderstorm Winds in the forecast period are $369 million. Region 5 can expect $162 million or 48% of the total statewide property losses.
Table 3.7.3: Severe Thunderstorm Wind Impact Forecast
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 36,829,691 31,544 5 32 3.75 Region 2 46,217,735 17,401,106 4 21 4.93 Region 3 27,143,618 348,986 4 10.28 Region 4 18,708,643 622,889 1 7 11.10 Region 5 162,451,173 11,585,803 3 23 109.12 Region 6 47,145,796 707,230 0 21 7.02 Total/St. 338,496,656 30,697,559 12 108 10.67
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 11% 0% 38% 30% 9,827,579 Region 2 14% 57% 29% 20% 9,367,616 Region 3 8% 1% 3% 2,640,570 Region 4 6% 2% 8% 7% 1,686,015 Region 5 48% 38% 22% 21% 1,488,783 Region 6 14% 2% 2% 20% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 67,699,331 6,139,512 2 22 2.13
The Ann Per-Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $67.7 million annual average statewide property losses expected in the forecast period. This is an increase of 5% over the base period. This increase is due to population and building exposure increases. There are no expected changes to Severe Thunderstorm Winds damage due to weather pattern changes.
As with Tornado’s, the region with the highest per capita forecast losses for Severe Thunderstorm Wind is Region 5. Region 5 does have the highest forecast property losses, but the fact that it also has the lowest forecast population helps to push the per capita amount higher.
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Risk Summary With expected dollar losses of almost $370 million over the forecast period ($74 million a year), Severe Thunderstorm Wind are a persistent and dangerous hazard in Texas. There were 9,199 reports of Severe Thunderstorm Wind impacts over the base period (53 times as many as for Hurricane TS/Ds). These provide a good basis for determining both the magnitude and the locations of future losses. The 9,199 data points that went into the model help produce a reliable depiction of how much damage there is likely to be in the future, and where that damage will likely occur.
Map 3.7.3 shows the Severe Thunderstorm Wind dollar loss forecast for 2019 – 2023 in Region 5 – the most at-risk region. This map, together with the statewide forecast map (Map 3.7.2) and the regional forecast table (Table 3.7.3) provide the best picture of expected future risks.
Map 3.7.3: Forecast Severe Thunderstorm Wind Dollar Losses in Region 5
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3.8: WILDFIRE
Wildfire is defined as a sweeping and destructive burning conflagration and can be further categorized as wildland, interface, or intermix fires.
Wildfire probability depends on local weather conditions, topographic factors and existing “fuels” such as native plants etc. Outdoor activities such as camping, debris burning, and construction; and the degree of public cooperation with fire prevention measures can affect the number and the extent of wildfires. Wildfires can result in widespread damage to property and loss of life. Lightning can cause, and drought and extreme heat can induce, wildfire events. Those hazards are considered elsewhere in this report.
Wildland fires are fueled almost exclusively by natural vegetation. Wildland/Urban Interface (WUI) fires are fueled by both vegetation and the built-environment. The wildfire disaster cycle begins when homes are built adjacent to wildland areas. When what would have been rural wildfires occur, they advance through all available fuels, which can include homes and other structures.
Other factors that affect wildfire behavior include fuel to wind exposure:
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With the semi-arid climate of the western, southern and panhandle counties of the state, wildland fires are most common in the spring and summer months, but can occur at any time during the year. The eastern part of the state, also known as the Piney Woods, contains the most hazardous fuels in the state: pine plantations. Fires burning in this fuel type under drought conditions are extremely hard to contain, require multiple fire-fighting resources, and threaten all homes in its vicinity. The “Hill Country” located in the central part of the state has the potential for future damaging wildfires due to a combination of rapid population growth, topography and densely covered, highly volatile, ash-juniper trees. This is especially true during extended and prolonged drought conditions. Some regions within the state can be expected to experience wildland fires whenever localized drought conditions are in place.
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There appears to be no dominant extent scale for wildfire. Local mitigation planners use various representations including number of contiguous acreage burned; length of flame; fire severity (the degree of damage on the landscape); or fire intensity. Fire intensity is the reported scale on the Texas A&M Forest Service TxWRAP portal http://www.texaswildfirerisk.com/
Characteristic Fire Intensity Scale (FIS) specifically identifies areas where significant fuel hazards and associated dangerous fire behavior potential exist based on a weighted average of four percentile weather categories. Similar to the Richter scale for earthquakes, FIS provides a standard scale to measure potential wildfire intensity. FIS consist of 5 classes where the order of magnitude between classes is ten-fold. The minimum class, Class 1, represents very low wildfire intensities and the maximum class, Class 5, represents very high wildfire intensities
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The table below provide explanation for the various Fire Intensity Scale (FIS) measures.
Fire Intensity Scale (FIS) Classes
CLASS 1 VERY VERY SMALL, DISCONTINUOUS FLAMES, USUALLY LESS THAN LOW ONE FOOT IN LENGTH; VERY LOW RATE OF SPREAD; NO SPOTTING. FIRES ARE TYPICALLY EASY TO SUPPRESS BY FIREFIGHTERS WITH BASIC TRAINING AND NON-SPECIALIZED EQUIPMENT.
CLASS 2 LOW SMALL FLAMES, USUALLY LESS THAN TWO FEET LONG; SMALL AMOUNT OF VERY SHORT RANGE SPOTTING POSSIBLE. FIRES ARE EASY TO SUPPRESS BY TRAINED FIREFIGHTERS WITH PROTECTIVE EQUIPMENT AND SPECIALIZED TOOLS.
CLASS 3 FLAMES UP TO 8 FEET IN LENGTH; SHORT-RANGE SPOTTING IS MODERATE POSSIBLE. TRAINED FIREFIGHTERS WILL FIND THESE FIRES DIFFICULT TO SUPPRESS WITHOUT SUPPORT FROM AIRCRAFT OR ENGINES, BUT DOZER AND PLOWS ARE GENERALLY EFFECTIVE. INCREASING POTENTIAL FOR HARM OR DAMAGE TO LIFE AND PROPERTY.
CLASS 4 HIGH LARGE FLAMES, UP TO 30 FEET IN LENGTH; SHORT-RANGE SPOTTING COMMON; MEDIUM RANGE SPOTTING POSSIBLE. DIRECT ATTACK BY TRAINED FIREFIGHTERS, ENGINES, AND DOZERS IS GENERALLY INEFFECTIVE, INDIRECT ATTACK MAY BE EFFECTIVE. SIGNIFICANT POTENTIAL FOR HARM OR DAMAGE TO LIFE AND PROPERTY.
CLASS 5 VERY VERY LARGE FLAMES UP TO 150 FEET IN LENGTH; PROFUSE HIGH SHORT-RANGE SPOTTING, FREQUENT LONG-RANGE SPOTTING; STRONG FIRE-INDUCED WINDS. INDIRECT ATTACK MARGINALLY EFFECTIVE AT THE HEAD OF THE FIRE. GREAT POTENTIAL FOR HARM OR DAMAGE TO LIFE AND PROPERTY.
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Historical Experience
Wildfire were the eighth most expensive weather-related hazard in Texas over the 21year base period. Table 3.8.1 shows property losses, crop losses, deaths and injuries attributed to Wildfires over the base period. All Regions suffered losses from Wildfires over this period. Region 5 had the most, receiving total losses of almost $460 million in losses: more than half of the total state losses from wildfire. At $300 million, Region 6 had more than a third of the total state losses
Table 3.8.1: Historical Wildfire Impacts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 72,215,570 5,215,662 6 30 8.37 Region 2 12,412,872 3,515,060 1.55 Region 3 15,622,528 60,945 8 6.45 Region 4 9,711,456 1,568,155 1 15 6.42 Region 5 273,911,995 185,920,455 20 108 191.61 Region 6 301,163,598 75,181 4 9 52.75 Total/St. 685,038,019 196,355,458 31 170 24.71
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 11% 3% 19% 18% 8,625,547 Region 2 2% 2% 8,027,607 Region 3 2% 0% 5% 2,421,457 Region 4 1% 1% 3% 9% 1,511,557 Region 5 40% 95% 65% 64% 1,429,523 Region 6 44% 0% 13% 5% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 32,620,858 9,350,260 1 8 1.18
Statewide Annual Losses over 12 years Ann Per Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 57,086,502 16,362,955 3 14 2.06
The annual average total dollar losses (property plus crop) over the 21-year base period was $42 million. However, a closer look at the data (below) reveals that data for this hazard was only collected since 2005. Dividing the total wildfire losses by the 12 years of data collection places the average annual losses 74% higher at $73.5 million: making Wildfire the seventh most costly hazard.
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Table 3.8.2 shows total dollar-losses by year for Wildfire from 2005 through 2016. Prior to 2005, the collection of this data within the NCEI Storm Event database was lacking. For this reason, the average annual cost information used for this hazard (show at the bottom of this table) is calculated over 12 years and not the standard 21 years of the base period used for other hazards. To use the 21-year period would artificially reduce the annual average losses and the forecasted impacts by 43%. The annual statewide totals for Wildfire dollar losses over the 12 year period went from a low of $214 thousand in 2007 to a high of $547 million in 2011: they averaged $73.5 million. Region 5’ annual average of $38.4 million was 52% of the state’s average annual losses.
Table 3.8.2: Annual Dollar-Losses from Wildfire
Region 1 Region 2 Region 3 Region 4 Region 5 Region 6 Totals 2005 8,155,018 183,948 13,514,029 21,852,995 2006 2,176,884 1,728,535 256,992,055 260,897,474 2007 40,668 173,300 213,968 2008 2,686,449 1,302,621 5,798,502 9,787,572 2009 2,076,784 12,817,996 10,973,456 25,868,236 2010 10,981 1,125,573 54,906 431,560 1,623,020 2011 61,000,620 14,802,359 516,486 9,339,329 161,011,307 300,619,785 547,289,886 2012 497,047 265,996 109,527 129,347 1,001,917 2013 443,024 169,603 51,395 16,447 680,469 2014 157,845 50,591 10,662,658 255,992 11,127,086 2015 55,580 505,274 111,160 672,014 2016 171,000 80,500 30,000 281,500 Totals 77,431,232 15,927,932 15,683,473 11,279,611 459,832,450 301,238,779 881,393,477
Average Annual Losses (12-years) $ Losses 6,452,603 1,327,328 1,306,956 939,968 38,319,371 25,103,232 73,449,456 Percent 8.8% 1.8% 1.8% 1.3% 52.2% 34.2% 100.0%
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County and Regional Dollar Losses Map 3.8.1 shows total county losses (property plus crop losses) from Wildfires over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had dollar losses due to wildfires. White represents zero dollar losses. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.8.1: Historical Dollar Losses from Wildfire
The predominance of Region 5 is apparent from examining this map. Region 6’s second place is due in large part to the Bastrop County Complex fire in September and October of 2011. Two people were killed by the fire and 1,673 homes were damaged or destroyed. The fire caused severe damage to Bastrop State Park and the Lost Pines Forest.
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Future Risks
Results of the hazard impact forecast for Wildfire are presented below along with a local assessment of those risks. Following this is a discussion more generalized risk and a summary of Wildfire risks statewide.
County Dollar Loss Forecast Map 3.8.2 shows the county forecasts for 2019-2023 for Wildfire dollar losses. These illustrate likely locations of future losses.
Map 3.8.2: Wildfire Dollar Loss Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations as during the based period. Future Wildfires dollar losses will not necessarily be in the same places they were in the past, but a strong correlation is likely.
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Regional Impact Forecast Regional forecasts for Wildfire impacts for the 5-year period 2019–2023 are shown in Table 3.8.3. Total statewide expected losses for Wildfires in the forecast period are $417 million. $328 million of that is forecast to be property losses. Region 6 can expect $152 million of those losses, 46% of the total. This hazard went from 8th most expensive in the base period (below Severe Thunderstorm Winds) to 7th most expensive (above Severe Thunderstorm Winds). Reasons for this include the expected growth in this hazard as well as the fact that the base period data was only for 12 years of the 21-year period.
Table 3.8.3: Wildfire Impact Forecasts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 33,864,213 2,377,085 3 14 3.45 Region 2 5,796,468 1,602,020 0.62 Region 3 7,560,048 27,776 4 2.86 Region 4 4,602,613 714,701 1 7 2.73 Region 5 124,027,752 84,734,928 9 50 83.31 Region 6 152,497,368 34,264 2 4 22.69 Total/St. 328,348,462 89,490,775 15 79 10.35
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 10% 3% 20% 18% 9,827,579 Region 2 2% 2% 9,367,616 Region 3 2% 0% 5% 2,640,570 Region 4 1% 1% 4% 9% 1,686,015 Region 5 38% 95% 63% 63% 1,488,783 Region 6 46% 0% 14% 5% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 65,669,692 17,898,155 3 16 2.07
The Ann Per-Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $65.7 million forecast annual average statewide property losses. This is an increase of 15% over the 12-year base period average. This increase is due to a combination of population and building exposure increases and expected increasing Wildfire damage due to weather pattern changes.
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3.9: WINTER WEATHER
Severe Winter Weather includes heavy snow and blizzards, sleet, ice storm (or freezing rain), Frost/Freeze or a mix of these. Severe winter weather can down trees, cause widespread power outages, damage property, and cause fatalities and injuries. Texas is disrupted more severely by severe winter storms than are regions that experience severe weather more frequently.
Extreme cold that often accompanies severe winter storms, can also be independent of a storm. For this reason, the historical and forecast future impact of Extreme Cold are presented separately, in section 3.11 below.
The type of winter weather that Texans are most familiar with are snowstorms, blizzards, and ice storms. A snowfall with an accumulation of four or more inches in a 12-hour period is considered a heavy snowfall. Snow accumulations of that amount are usually experienced in the northern half of the state and in the higher elevations of West Texas.
Snowfall of any amount is rare south of a line from Del Rio to Port Arthur, and it is this rarity of event, coupled with a lack of preparedness for such an event, that creates severe weather conditions when they do occur.
Blizzards are the most perilous of all winter storms, characterized by low temperatures and strong winds in excess of 35 mph, bearing large amounts of blowing or drifting snow. Blizzards take a terrible toll in livestock and people caught in the open. In Texas, blizzards are most likely to occur in the Panhandle and South Plains Regions.
An ice storm occurs when rain falls out of the warm and moist upper layers of the atmosphere into a cold and dry layer near the ground. The rain freezes on contact with the cold ground and accumulates on exposed surfaces. If a half inch of rain freezes on trees and utility wires, damage can occur, especially if accompanied by high winds, thus half an inch is used as the criteria before an icing event is categorized as an “ice storm.”
The Texas Panhandle and North Central Texas around Dallas and Texarkana are most vulnerable to severe winter storms. At the same time, these areas are better prepared for severe winter weather. The southern portions of the state are not as likely to incur severe winter weather, but when it does happen, the impacts are much stronger because the communities and governments are not as prepared.
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Historical Experience
In 2016 dollars, the total annual average dollar losses due to Winter Weather in Texas over base period was $24.5 million: making it ninth out of the twelve weather related hazards, in terms of financial impact. Table 3.9.1 below, shows property losses, crop losses, deaths and injuries attributed to Winter Weather over the base period. All Regions in Texas suffered losses from Winter Weather over this period. However, Region 1 with almost $350 million, experienced 70% of the property losses associated with this hazard. Winter weather was third out of 12 in terms of the number of deaths that resulted. Region 5’s 64 deaths was more that 8 of the 12 hazards resulted in statewide. More than 95% of the injuries related to this hazard are in Regions 1 and 5. Region 1 ranks fourth in total dollar losses due to this hazard, but first in terms of deaths and injuries that resulted from it.
Table 3.9.1: Historical Winter Weather Impacts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 349,893,852 36 966 40.56 Region 2 28,759,606 6 20 3.58 Region 3 10,413,863 11,893,161 4 3 4.30 Region 4 1,694,614 449,707 14 20 1.12 Region 5 98,824,679 5,118,347 64 442 69.13 Region 6 7,399,423 153,064 14 35 1.30 Total/St. 496,986,037 17,614,279 138 1,486 17.93
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 70% 26% 65% 8,625,547 Region 2 6% 4% 1% 8,027,607 Region 3 2% 68% 3% 0% 2,421,457 Region 4 0% 3% 10% 1% 1,511,557 Region 5 20% 29% 46% 30% 1,429,523 Region 6 1% 1% 10% 2% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 23,666,002 838,775 7 71 0.85
The Ann Per-Cap Prop Losses, times the 27.7 million estimated 2016 state population equals the $23.6 million annual average property losses statewide in the base period.
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Table 3.9.2 shows total dollar-losses by year for winter weather over the base period. The annual statewide totals for winter weather dollar losses over the 21- year period went from a low of zero in 2016 to a high of $218 million in 2000: they averaged $24.5 million. Region 1 average $16.7 million (68%) of those losses. Regions 1 and 5, the northern most regions together made up more than 88% of the total losses due to winter weather.
Table 3.9.2: Annual Dollar-Losses from Winter Weather
Region 1 Region 2 Region 3 Region 4 Region 5 Region 6 Totals 1996 30,529 15,264 610,580 763,225 2,518,642 3,938,240 1997 26,859,813 9,132,336 4,849,689 40,841,838 1998 198,360 198,360 1999 15,180,794 15,180,794 2000 214,882,405 1,390,823 6,954 1,731,580 218,011,762 2001 338,086 338,086 2002 59,908 59,908 2003 19,524,457 7,810 352,740 7,810 19,892,817 2004 88,751 88,751 2005 85,842 170,458 256,300 2006 47,520 2,376 2,562,509 2,612,405 2007 814,511 76,250 488,704 4,683,714 2,294,486 8,357,665 2008 4,149,478 4,149,478 2009 2,516,707 8,954,739 242,294 11,713,740 2010 54,194,424 39,532 5,274,269 847,747 60,355,972 2011 4,820,891 33,013 12,869,533 2,587,753 298,178 20,609,368 2012 1,251,742 1,037,904 2,289,646 2013 50,010,270 102,790 1,027,897 14,801,714 1,140,965 67,083,636 2014 1,281,988 60,709 202,365 177,070 202,365 1,924,497 2015 518,408 36,178,645 36,697,053 2016 Totals 349,893,852 28,759,606 22,307,024 2,144,321 103,943,026 7,552,487 514,600,316
Average Annual $ Losses 16,661,612 1,369,505 1,062,239 102,111 4,949,668 359,642 24,504,777 Percent 68.0% 5.6% 4.3% 0.4% 20.2% 1.5% 100.0%
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Historical Dollar Losses Map 20 shows total county losses (property plus crop losses) from Winter Weather over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20% of the counties that had these sorts of impacts -white represents zero dollar losses. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.9.1: Historical Winter Weather Dollar Losses
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Future Risks
Results of the hazard impact forecast for Winter Weather are presented below. Following this is a discussion more generalized risk and a summary of Winter Weather risks statewide.
County Dollar Loss Forecast Map 3.9.2 shows the county forecasts for 2019-2023 for Winter Weather dollar losses. These illustrate historical and like likely locations of future losses.
Map 3.9.2: Winter Weather Dollar Losses Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations during the forecast period as they did during the based period.
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Regional Impact Forecast Regional forecasts for Winter Weather impacts for the 5-year period 2019–2023 are shown in Table 3.9.3. The statewide total forecast costs for Winter Weather in the period are $103.6 million. Region 1 can expect $69 million of those losses: 70% of the total.
Table 3.9.3: Winter Weather Impact Forecasts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 69,909,469 8 211 7.11 Region 2 5,884,263 1 4 0.63 Region 3 2,103,476 2,412,389 1 1 0.80 Region 4 343,071 91,218 3 4 0.20 Region 5 20,256,552 1,038,197 13 92 13.61 Region 6 1,584,328 31,047 3 7 0.24 Total/St. 100,081,159 3,572,851 29 319 3.15
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 70% 27% 66% 9,827,579 Region 2 6% 4% 1% 9,367,616 Region 3 2% 68% 3% 0% 2,640,570 Region 4 0% 3% 10% 1% 1,686,015 Region 5 20% 29% 45% 29% 1,488,783 Region 6 2% 1% 10% 2% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 20,016,232 714,570 6 64 0.63
The Ann Per-Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $20 million annual average statewide property losses expected in the forecast period. Compared with the average annual base period losses of $23.6 million, this is a 15% decrease This decrease is in spite of population and building exposure increases, and is explained by the expected decreasing of Winter Weather damage due to weather pattern changes. This is one of only two hazards with expected decreases in future losses. Both are due to weather pattern changes that are expected to decrease the frequency and intensity of those hazards. The other hazard that is expected to decrease is the 11th most expensive hazard: Extreme Cold.
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3.10: LIGHTNING
Lightning is a massive electrostatic discharge between electrically charged regions within clouds, or between a cloud and the Earth's surface. Lightning can strike communications equipment (i.e. radio and cell towers, antennae, satellite dishes, etc.) and hamper communication and emergency response. Lightning strikes can also cause significant damage to buildings, critical facilities, and infrastructure, largely by igniting a fire. Lightning can strike and kill people, it can also ignite wildfires (as discussed in Section 3.8 above).
The following forms of lightning are defined by The National Lightning Safety Institute (http://www.lightningsafety.com):
Direct Strike - This is the most dangerous hazard, wherein the person or structure is in a direct path for lightning currents to seek ground. The magnitude of the current determines its effects. A typical amperage of 2OkA acting on a ground of 10 ohms creates 200,000V. A large strike can attain l5OkA levels.
Side Strike - This hazard results from the breakup of the direct strike when alternate parallel paths of current flow into the ground via a person or structure. When the initial current path offers some resistance to current flow, a potential above ground develops and the person or structure's resistance to ground becomes the alternate path of conduction.
Conducted Strike - This hazard occurs when lightning strikes a conductor which in turn introduces the current into an area some distance from the ground strike point. Unprotected connected equipment can be damaged and personnel injured if they become an indirect path in the completion of the ground circuit.
Structure Voltage Gradient - When current passes through two or more structures momentary voltage differentials are created. Poor interconnect bonding may cause a completed circuit potential difference. The same hazard is created, for example, by a person touching an ungrounded object while he himself is grounded. The electrical circuit is completed through him, sometimes with fatal consequences.
Induced Effects - Lightning can induce electric field and magnetic field coupling into structures and into wiring. Magnetic coupling is transformer action, and the common laws for transformers prevail.
Streamer Conductor - The streamer hazard occurs when a lightning leader influences electric behavior of objects on the earth. Even streamers which do not become a part of the main channel can contain significant amounts of current. Streamer current exposure can affect people and sensitive electronics.
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Sequelae - These secondary effects are many. Forest and grass fires, explosive steam conditions in masonry, trees and other water-bearing objects, and consequences of the thunder clap startling a person so as to drop a wrench or inadvertently throw a switch are examples.
Step Voltage/Touch Voltage - This hazard occurs as a result of a lightning strike hitting the ground and dissipating its energy through the ground. The ground current creates a voltage drop across the surface of the earth, emanating from the earth entry point radially. A person standing on the earth within several hundred feet from the lightning strike point can have several hundred volts generated between his feet. This hazard is identical to a person being grounded while touching two live wires, one with each hand.
The National Lightning Detection Network, NLDN, consists of over 100 remote, ground-based sensing stations located across the US. Electromagnetic signals given off when lightning strikes the earth's surface are sent via satellite to the Network Control Center (NCC) operated by Vaisala Inc. in Tucson, Arizona. Within seconds, the NCC's central analyzers process the location, time, polarity, and communicates to users across the country. The map below shows significant lightning hazard risk zones for the entire U.S. expressed in the number of expected cloud-to-ground strikes per square mile per year. The Houston and Beaumont/Port Arthur metropolitan areas on the upper Texas Gulf coast are the highest risk areas.
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Historical Experience
In 2016 dollars, the annual average dollar losses due to Lightning in Texas over the 21 year base period was $3,234,744. This was the 10th most expensive weather- related hazard in Texas over that period. However, 57 deaths were reported from this hazard making it fifth out of twelve as a cause of death.
Table 3.10.1 below, shows property losses, crop losses, deaths and injuries attributed to Lightning. All regions suffered losses from Lightning over this period. Region 1 had the largest amount ($36 million) and share (54%) of property losses, Region 2 had the largest number and percent of deaths and injuries. There were few crop losses reported with this hazard. Lightning is potential a cause of fire, but those impacts would be reported under the Wildfire hazard.
Table 3.10.1: Historical Lightning Impacts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 36,372,256 11 49 4.22 Region 2 15,904,409 1,028 28 133 1.98 Region 3 2,386,867 2 7 0.99 Region 4 908,412 1 3 0.60 Region 5 6,215,910 103 5 11 4.35 Region 6 6,140,647 10 49 1.08 Total/St. 67,928,501 1,131 57 252 2.45
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 54% 19% 19% 8,625,547 Region 2 23% 91% 49% 53% 8,027,607 Region 3 4% 4% 3% 2,421,457 Region 4 1% 2% 1% 1,511,557 Region 5 9% 9% 9% 4% 1,429,523 Region 6 9% 18% 19% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 3,234,691 54 3 12 0.12
The Ann Per-Cap Prop Losses, times the 27.7 million estimated 2016 state population equals the $3.2 million annual average property losses statewide in the base period.
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Table 3.10.2 shows total dollar-losses by year for lightning over the base period. The annual statewide totals for winter weather dollar losses over the 21-year period went from a low of $270 thousand in 2000 to a high of $9.5 million in 1997: they averaged $3.2 million. Region 1, the only region with losses every year of the period, averaged $1.7 million (53%) of those losses. . Table 3.10.2: Annual Dollar-Losses from Lightning
Region 1 Region 2 Region 3 Region 4 Region 5 Region 6 Totals 1996 2,108,025 3,356,663 1,221,159 3,053 6,688,900 1997 602,852 8,542,912 201,448 141,760 9,488,972 1998 947,717 146,932 14,693 76,405 17,926 88,159 1,291,832 1999 2,379,188 28,752 1,221,953 14,376 3,644,269 2000 257,303 13,213 270,516 2001 1,528,148 9,466 416,928 1,954,542 2002 965,189 179,725 146,443 1,291,357 2003 3,554,753 390,489 97,622 676,848 4,719,712 2004 324,574 25,357 95,090 6,339 228,216 253,573 933,149 2005 813,051 269,790 134,895 28,206 49,053 1,294,995 2006 1,384,016 253,044 35,640 403,919 2,076,619 2007 2,146,952 432,094 17,330 9,243 226,444 23,107 2,855,170 2008 1,645,242 337,057 12,236 569,549 895,483 3,459,567 2009 4,840,585 169,716 1,291,848 558,276 884,310 7,744,735 2010 2,774,178 382,366 222,918 576,513 878,496 4,834,471 2011 1,013,271 543,109 6,922 5,325 414,253 127,790 2,110,670 2012 4,143,268 26,077 36,510 99,096 144,587 4,449,538 2013 1,143,227 340,233 10,279 270,954 1,379,438 3,144,131 2014 1,240,503 416,872 10,118 1,012 25,295 1,693,800 2015 1,266,214 334,490 136,423 101,055 10,105 38,400 1,886,687 2016 1,294,000 149,000 532,500 7,500 113,000 2,096,000 Totals 36,372,256 15,905,437 2,386,867 908,412 6,216,013 6,140,647 67,929,632
Average Annual $ Losses 1,732,012 757,402 113,660 43,258 296,001 292,412 3,234,744 Percent 53.5% 23.4% 3.5% 1.3% 9.2% 9.0% 100.0%
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County Dollar Losses Map 3.10.1 shows total county losses (property plus crop losses) from lightning over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had these sorts of impacts -white represents zero dollar losses. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.10.1: Historical Lightning Dollar Losses
143 CHAMPS ’17: A Hazard Assessment for Texas
Future Risks
Results of the hazard impact forecast for Lightning are presented below. Following this is a discussion more generalized risk and a summary of Lightning risks statewide.
County Dollar Loss Forecast Map 3.10.2 shows the county forecasts for 2019-2023 for Lightning dollar losses. These illustrate historical and like likely locations of future losses.
Map 3.10.2: Lightning Dollar Losses Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations during the forecast period as they did during the based period.
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Regional Impact Forecast Regional forecasts for Lightning impacts for the 5-year period 2019–2023 are shown in Table 3.10.3. Total statewide costs for Lightning in the forecast period are expected to be $17.6 million. Region 1 can expect $9.5 million of those losses, or about 54% of the total.
Table 3.10.3: Lightning Impact Forecasts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 9,474,662 3 12 0.96 Region 2 4,131,918 245 7 33 0.44 Region 3 607,714 1 2 0.23 Region 4 237,601 0 1 0.14 Region 5 1,519,222 25 1 3 1.02 Region 6 1,589,215 3 13 0.24 Total/St. 17,560,332 269 15 64 0.55
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 54% 19% 19% 9,827,579 Region 2 24% 91% 50% 52% 9,367,616 Region 3 3% 3% 3% 2,640,570 Region 4 1% 2% 1% 1,686,015 Region 5 9% 9% 9% 4% 1,488,783 Region 6 9% 17% 20% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 3,512,066 54 3 13 0.11
The Ann Per-Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $5.5 million annual average statewide property losses expected in the forecast period. This is an increase of 9% over the base period. This increase is due to a population and building exposure increases only. There were no expected changes to lightning damage due to weather pattern changes.
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3.11: EXTREME COLD
Extreme cold can be relative. In the panhandle extreme cold means days below zero Fahrenheit. In the Rio Grande Valley means temperatures below freezing long enough to damage citrus crops.
Extreme cold can accompany severe winter storms. It can also be independent of a those storms. For this reason, the impacts of Extreme Cold are presented here separately from the impacts of the severe winter (snow, sleet, freezing rain, or a mix of these wintry forms of precipitation) discussed in Section 3.9, above.
The passage of a winter cold front with a drastic drop in temperature heralds the arrival of a cold wave, usually referred to as a “blue norther.”
The map below shows expected annual minimum temperatures across the state of Texas. When dealing with the impacts of these temperatures on people, it is important to consider the wind-chill effect, shown on the table below this map/
Annual Minimum Temperatures in Texas
146 CHAMPS ’17: A Hazard Assessment for Texas
Wind chill temperature is a measure of how cold the wind makes real air temperature feel to the human body. Since wind can dramatically accelerate heat loss from the body, a 30° day would feel just as cold as a calm day with 0° temperatures. The wind Chill index was created in 1870, and on November 1, 2001, the NWS released a more scientifically accurate equation which we use today.
Following is a chart for calculating wind chill. (Please note that it is not applicable in calm winds or when the temperature is over 50°).
147 CHAMPS ’17: A Hazard Assessment for Texas
Historical Experience
Extreme Cold is the eleventh most expensive weather-related hazard in Texas over the base period. Table 3.11.1 below, shows property losses, crop losses, deaths and injuries attributed to Extreme Cold. All Regions suffered some losses from Extreme Cold over this period – though not in all impact categories. At $5.4 million and 40 % of the property losses, Region 4 led that category. At $4.6 million and 35 % of the property losses, Region 5 was not far behind. Region 1 ranks third in total dollar losses, but first in deaths that resulted from it. Regions 3’s losses of $1.8 million were all from crop damages – as might be expected when unusual freezes hit agricultural areas.
Table 3.11.1: Historical Extreme Cold Impacts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 1,938,183 14 0.22 Region 2 1,558,784 2 0.19 Region 3 1,831,740 Region 4 5,377,835 3.56 Region 5 4,688,293 596,884 2 6 3.28 Region 6 1 Total/St. 13,563,095 2,428,624 19 6 0.49
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 14% 74% 8,625,547 Region 2 11% 11% 8,027,607 Region 3 75% 2,421,457 Region 4 40% 1,511,557 Region 5 35% 25% 11% 100% 1,429,523 Region 6 5% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 645,862 115,649 1 0 0.02
Though extreme cold is ranked as 11th out of 12 in financial cost, it is 9th out of 12 as a cause of death.
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Table 3.11.2 shows total dollar-losses by year from Extreme Cold over the base period. This table shows only those four years for which dollar losses are reported. 17 of 21 years had zero dollar losses reported. 2011, with $7 million, was the highest single year. No dollar losses were reported in region 6 over the period (though one death was attributed). Regions 4 and 5 received 66.6% of the dollar losses: each averaged over a quarter million dollars losses annually over the 21- year base period. Table 3.11.2: Annual Dollar-Losses from Extreme Cold
Region 1 Region 2 Region 3 Region 4 Region 5 Totals 1996 76,322 1,831,740 1,908,062 1997 3,581,308 3,581,308 2010 1,938,183 1,482,462 3,420,645 2011 5,377,835 1,703,869 7,081,704 Totals 1,938,183 1,558,784 1,831,740 5,377,835 5,285,177 15,991,719
Average Annual $ Losses 92,294 74,228 87,226 256,087 251,675 761,510 Percent 12.1% 9.7% 11.5% 33.6% 33.0% 100.0%
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Historical Dollar Losses Map 3.11.1 shows total county losses (property plus crop losses) from Extreme Cold over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had these sorts of impacts -white represents zero dollar losses. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.11.1: Historical Extreme Cold Dollar Losses
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Future Risks
Results of the hazard impact forecast for Extreme Cold are presented below. Following this is a discussion more generalized risk and a summary of Extreme Cold risks statewide.
County Dollar Loss Forecast Map 3.11.2 shows the county forecasts for 2019-2023 for Extreme Cold-related dollar losses. These illustrate historical and like likely locations of future losses.
Map 3.11.2: Extreme Cold Dollar Losses Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations during the forecast period as they did during the based period.
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Regional Impact Forecast Regional forecasts for Extreme Cold impacts for the 5-year period 2019–2023 are shown in Table 3.11.3. The statewide total forecast costs for Extreme Cold in the period are $3.4 million. Region 4 can expect over a million of those losses: 41% of the total.
Table 3.11.3: Extreme Cold Impact Forecasts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 421,718 3 0.04 Region 2 331,082 0 0.04 Region 3 388,206 Region 4 1,231,676 0.73 Region 5 987,576 126,499 0 1 0.66 Region 6 0 Total/St. 2,972,052 514,705 4 1 0.09
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 14% 74% 9,827,579 Region 2 11% 10% 9,367,616 Region 3 75% 2,640,570 Region 4 41% 1,686,015 Region 5 33% 25% 10% 100% 1,488,783 Region 6 5% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 594,410 102,941 1 0 0.02
The Ann Per-Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $594 million annual average statewide property losses expected in the forecast period. This is a decrease of 8% from base period amounts. This decrease is in spite of population and building-exposure increases. It is due entirely to expected decreasing Extreme Cold because of weather pattern changes. This is one of two hazards with expected decreases in damage due to weather pattern changes. The other is 9th most expensive hazard: Winter Weather.
152 CHAMPS ’17: A Hazard Assessment for Texas
3.12: EXTREME HEAT
Extreme Heat is defined as a combination of very high temperatures and, usually, exceptionally humid conditions. When persisting over a period of time, it is called a heat wave.
All of Texas is vulnerable to extreme heat, but most particular in West Texas. In addition, large metropolitan areas, such as Dallas/Fort Worth and Houston may experience extreme heat since they have an abundance of concrete which absorb and then radiate solar energy. This effect is known as urban heat island and can be dangerous to those without functioning air conditioners.
The map below shows the amount that the mean monthly temperatures varied from normal during July 2011 (in the midst of the 2011 – 2012 drought. More than 50% of the State at this time had mean monthly temperatures more the 4 degrees over normal.
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Historical Experience
Extreme Heat was the least expensive weather-related hazard over the base period, but second only to floods in terms on the number of people it killed. Table 3.12.1 shows property losses, crop losses, deaths and injuries attributed to Extreme Heat. Though financial impacts were relatively small and sparsely distributed across the state, all regions suffered deaths from Extreme Heat. Regions 1 and 2 account for 85% of the deaths due to Extreme Heat. Extreme Heat killed more people in these regions than any other weather-related hazard.
Table 3.12.1: Historical Extreme Heat Impacts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 212,984 144 935 0.02 Region 2 150 2 Region 3 14 2 Region 4 1 Region 5 55,620 556,200 9 2 0.04 Region 6 28 Total/St. 268,604 556,200 346 941 0.01
% of % of % of % of 2016 Pop. Prop. Losses Crop Losses Deaths Injuries Estimate Region 1 79% 42% 99% 8,625,547 Region 2 43% 0% 8,027,607 Region 3 4% 0% 2,421,457 Region 4 0% 1,511,557 Region 5 21% 100% 3% 0% 1,429,523 Region 6 8% 5,709,501 Total/St. 100% 100% 100% 100% 27,725,192
Statewide Annual Losses over 21 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 12,791 26,486 16 45 0.0005
The Ann Per-Cap Prop Losses, times the 27.7 million estimated 2016 state population equals the $13 thousand annual average property losses statewide in the base period. There were more than twice as much crop losses in Region 5 than property losses statewide from Extreme Heat. The annual average total dollar losses (property plus crop) due to Extreme Heat in Texas over the base period was $39,276.
154 CHAMPS ’17: A Hazard Assessment for Texas
Table 3.12.2 shows total dollar-losses (property plus crop) by year from Extreme Heat over the base period. This table differ from others of this type in that is shows only those two years for which dollar losses were reported and only the two regions that had losses reported. 19 of 21 years had zero dollar losses, while 2008, with $611 thousand, was the highest single year. No dollar losses were reported in regions 2, 3, 4 and 6 over the period (deaths were attributed to Extreme Heat in all regions). Regions 5 received 74% of the dollar losses from Extreme Heat over the period. Table 3.12.2: Annual Dollar-Losses from Extreme Heat
Region 1 Region 5 Totals 2008 611,820 611,820 2011 212,984 212,984 Totals 212,984 611,820 824,804
Average Annual $ Losses 10,142 29,134 39,276
Percent 25.8% 74.2% 100.0%
155 CHAMPS ’17: A Hazard Assessment for Texas
Historical Dollar Losses
Map 3.12.1 shows total county losses (property plus crop losses) from Extreme Heat over the period 1996 thru 2016. County colors indicate their losses relative to other counties in the state. Each color represents approximately 20 % of the counties that had these sorts of impacts -white represents zero dollar losses. The inset table reports total dollar losses by DPS Region for each region over the period.
Map 3.12.1: Historical Extreme Heat Dollar Losses
156 CHAMPS ’17: A Hazard Assessment for Texas
Sample Episode Description
The following description of an Extreme heat related episo9de is from the NCEI database. It describes events that occurred in Dallas County in July of 1998
A prolonged excessive heat event continued across north Texas in July. This heat wave was the result of existing drought conditions combined with a persistent upper level ridge of high pressure. For the month of July, Dallas/Fort Worth International Airport (DFW) recorded an average high of 102.4 degrees, which was the second warmest for the month on record and the fourth warmest ever. The average low of 80.8 degrees was the warmest average low for any month. The monthly average temperature of 91.6 degrees was the second warmest month on record, second only to the 92.0 degrees recorded during the heat wave in July of 1980. DFW reported 28 days with high temperatures at or above 100 degrees and 26 days with low temperatures at or above 80 degrees. The high temperature of 110 degrees reported at DFW on July 12th was the warmest high temperature recorded since July 18, 1980.
In Waco, the average temperature of 90.4 degrees was the third warmest on record, with highs averaging 102.4 degrees and lows averaging 78.3 degrees. Waco also reported 26 days with highs at or above 100 degrees. The warmest high temperature for the month for north Texas was reported in Fort Worth on July 13th, when the mercury topped out at 112 degrees. During July, the heat wave claimed at least 32 lives in north Texas, with most of the fatalities occurring in the Dallas/Fort Worth Metroplex. Most of the fatalities were elderly, and many fatalities listed other complicating factors, such as heart disease and hypertension.
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Future Risks
Results of the hazard impact forecast for Extreme Heat are presented below along with a local assessment of those risks. Following this is a discussion more generalized risk and a summary of Extreme Heat risks statewide.
County Dollar Loss Forecast Map 3.12.2 shows the county forecasts for 2019-2023 for Extreme Heat dollar losses. These illustrate historical locations of losses. Because there are so few data points represented, it is likely that future impact locations will differ from this.
Map 3.12.2: Extreme Heat Dollar Losses Forecast
This forecast estimates damages that are likely to occur in the forecast period if similar weather events occur in similar locations as during the based period.
158 CHAMPS ’17: A Hazard Assessment for Texas
Regional Impact Forecast Forecasts for Regional Extreme Heat impacts for 2019–2023 are shown in Table 3.12.3. Total statewide costs for Extreme Heat in the forecast period are $233 thousand. Region 1 can expect $62 thousand, 79% of the total. Though this is the least costly of all weather-related hazards in terms of property and crop losses, it is expected to replace Riverine Flooding as the most deadly, killing more than 100 people over the 5-year forecast period.
Table 3.12.3: Extreme Heat Impact Forecasts
Property Losses Crop Losses Per-Cap (2016 dollars) (2016 dollars) Deaths Injuries Prop Losses Region 1 61,684 43 278 0.01 Region 2 46 1 Region 3 4 1 Region 4 0 Region 5 16,548 155,212 3 1 0.01 Region 6 9 Total/St. 78,232 155,212 105 280 0.00
% of % of % of % of 2024 Pop. Prop. Losses Crop Losses Deaths Injuries Forecast Region 1 79% 41% 99% 9,827,579 Region 2 44% 0% 9,367,616 Region 3 4% 0% 2,640,570 Region 4 0% 1,686,015 Region 5 21% 100% 2% 0% 1,488,783 Region 6 8% 6,719,781 Total/St. 100% 100% 100% 100% 31,730,345
Statewide Annual Forecast Losses over 5 years Ann Per-Cap Property Losses Crop Losses Deaths Injuries Prop Losses Ann Avg 15,646 31,042 21 56 0.0005
The Ann Per-Cap Prop Losses, times the 31.7 million forecast 2024 state population equals the $15 thousand annual average statewide property losses expected in the forecast period. This is an increase of 22% over the base period. This increase is due to a combination of population and building exposure increases and expected increasing Extreme Heat damage due to weather pattern changes.
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County Deaths and Injury Forecast Since Extreme Heat is forecast to cause the greatest number of deaths of any weather-related hazard in the forecast period, it is important to see where those deaths are forecast to happen.
Map 3.12.3 shows the county forecasts for 2019-2023 for Extreme Heat deaths and injuries. This map shows, based on past experience and reasoned extrapolations of population/development changes and weather pattern changes, where future deaths and injuries can be expected.
Map 3.12.3: Extreme Heat Deaths and Injuries Forecast
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Section 4 – Other Hazard Risks
The following hazards are discussed in subsections as identified below: 4.1: Coastal Erosion; 4.2: Inland Erosion; 4.3: Subsidence; and 4.4: Earthquakes.
The first two of these are tied into the weather related hazards presented in Section 3, but they are not related on a one-to-one basis to any single hazard. They are related to multiple hazards including Hurricane TS/D, Drought, Severe Coastal Floods, and Riverine Flooding. Some of the losses reported under those hazards were due to erosion. The nature of these hazard is such that they deserve separate treatment.
The state has a major multiyear program that address coastal erosion. Based on the State Coastal Erosion Planning and Response Act (CEPRA) passed by the Texas Legislature in 1999, the General Land Office has managed 9 2-year cycles of CEPRA Program projects to limit and reduce coastal erosion. There are many benefits to these program discussed below, but it is worth noting here that reducing and reversing coastal erosion (and wetland degradation) help to mitigate Hurricane TS/D and Severe Coastal Flooding impacts.
Inland erosion is being added to the hazards addressed in the state’s Hazard Mitigation Plan for the first time in this cycle. It has been a topic of concern for the Federal government for more than 80 years. The federal government created the Soil Conservation Service in 1935 as a response to the “Dust Bowl” in the Great Plains in the early 1930s. The Texas State Soil and Water Conservation Board was created in 1939 It is now the state agency that administers Texas’ soil and water conservation law and coordinates nonpoint source water pollution abatement programs across the state.
Subsidence is a hazard that is mostly under control in Texas. There is an ongoing success story to be told about how that hazard has been and is being mitigated in the Houston area. Although it was the uncoordinated growth in that area that largely created the problem in the first place and the strategies to mitigate further subsidence there continue to meet with development pressures, if other hazard risks were as well understood and mitigatable as subsidence, Texas would be fortunate.
Earthquakes are less of an issue in Texas than in most other states. The hazard assessment however, would not be complete without a discussion of those risks. 161 CHAMPS ’17: A Hazard Assessment for Texas
4.1: COASTAL EROSION
Coastal erosion is a hydrologic hazard defined as the wearing away of land and loss of beach, shoreline, or dune material because of natural coastal processes or manmade influences. Coastal erosion is linked to Hurricane damage in that healthy coastal dunes and beaches help reduce impacts of Hurricane TS/Ds and Severe Coastal Flooding. Mitigating Coastal Erosion also mitigates those hazards.
Erosion is measured as a rate of change in the position or displacement of a shoreline over a period of time. Short-term erosion typically results from periodic natural events, such as wave action, storm surges and wind. Long-term erosion is a result of repetitive events of this type and of severe storm and flooding events.
Erosion can affect natural and built environments. Impacts depend on topography, soils, building types and construction materials. Coastal erosion can affect natural systems, coastal food supplies, tourist industry and small town viability. When sea water gets into wetlands whose ecosystems depend on that freshwater, they can die away – removing key habitats for animals and a protective buffer for nearby communities.
At 367 miles, Texas has one of the longest coastlines in America. It also has some of the highest rates of coastal erosion in the nation. Coastal erosion can be mitigated by dune and beach reinstatement programs as well as by building seawalls and placing Rip-Rap and other semi-permanent obstructions perpendicular to beaches. Coastal Erosion mitigation actions have the benefit of helping reduce impacts from Hurricanes and Severe Coastal Flooding.
The state has a program to address coastal erosion that is managed by the Texas General Land Office (GLO). The GLO reports its progress every two- years to the Texas Legislature in Coastal Erosion Planning and Response Act Reports. Much of the following discussion, came from these reports.
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Several processes contribute to chronic (long-term) or episodic (storm-induced) shoreline erosion of the Texas Gulf Coast. These include climate, tides, relative sea- level rise, subsidence, tropical storms, and the amount and rate of sediment supply. Coastal erosion affects both Gulf and bay shorelines, resulting in the loss of agricultural, industrial, residential land, critical infrastructure, and wetlands. Climatic changes (from wetter to drier) have decreased the volume of sediments carried to the Texas coast by rivers. The following map shows net coastal Accretion in positive values (green) and erosion in negative values (yellow thru Red). These change rates are based on information from 11,731 individual measurements sites.
Source: Erosion rates determined by the University of Texas Bureau of Economic Geology
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The 367 miles of the Texas gulf-facing shoreline is predominantly composed of low- elevation sandy beaches that are part of numerous long, narrow barrier island complexes, barrier peninsulas, and delta headlands. Behind these gulf-facing shores, an additional 3,300 miles of bay shorelines surround the many bays and estuaries that formed near the mouths of river systems. The majority of these gulf and bay shorelines are retreating due to coastal erosion.
The table below shows the extent of Texas coastal erosion. Eighty percent of the Texas gulf shoreline is retreating with a coast-wide average rate of retreat of approximately four feet per year, with some extreme areas losing as much as 55 feet per year. Sixty-one percent of the Texas gulf shoreline is classified as eroding where the rate of shoreline retreat is greater than two feet per year. The areas experiencing the highest erosion rates are located along the upper Texas coast from Matagorda County northward, and on the lower Texas coast along South Padre Island in Willacy and Cameron counties.
Miles of Eroding Shoreline on the Texas Coast* Total Total Percent Coastal Eroding Eroding Region Miles Miles Shoreline 1-Sabine Pass to Bolivar Roads (Galveston County) 59.0 47.6 80.6%
2-Bolivar Roads to San Luis Pass 29.0 13.9 48.1%
3-San Luis Pass to Old Colorado River 63.1 45.6 72.3%
4-Old Colorado River to Aransas Pass 83.7 45.3 54.1%
5-Aransas Pass to Padre Island National Seashore 27.3 11.3 41.4%
6-Padre Island National Seashore to Mansfield Cut 64.1 29.2 45.5%
7-Mansfield Cut to Rio Grande River/U.S. Border 40.8 32.1 78.6%
Total 367.0 224.9 61.3%
* As determined from average gulf shoreline erosion rates greater than 2ft/yr. measured over the past 70 years by the University of Texas Bureau of Economic Geology.
On average, 235 acres of land along the Texas Gulf Coast and the state’s bays, estuaries, and navigation channels are lost each year to erosion. That is equivalent to 178 football fields lost each year.
164 CHAMPS ’17: A Hazard Assessment for Texas
Coastal erosion results in the loss of property, which negatively affects property values and reduces tourism opportunities in local communities. Other coastal resources impacted by coastal erosion include the Gulf Intracoastal Waterway (GIWW), ports and ship channels, petrochemical facilities, road infrastructure, and other types of commercial businesses. According to the GLO coastal erosion is a threat to: • Public health, safety or welfare; • Public beach use or access; • General recreation; • Traffic safety; • Public property or infrastructure; • Private, commercial, and residential property; • Fish or Wildlife habitat; and • Any area of regional or nation importance along the Texas coast.
Some coastal areas are in need of beach nourishment and dune restoration. A healthy beach/dune system can minimize damage to homes and critical infrastructure by absorbing energy from storm surge and waves, and providing sediment to the beach. Wide beaches and high continuous dunes are the best defense against coastal storms. The significance of sand dunes to coastal protection is highlighted in studies by the U.S. Geological Survey.
In 2008, 100,000 cubic yards of beach-quality sand was placed on 4,600 feet of shoreline within Cameron County Isla Blanca Park and the City of South Padre Island due to erosion associated with Hurricane Dolly as well as long-term chronic erosion. Subsequently, in 2010, 2011 and 2012, beach nourishment through the beneficial use of dredged material has placed approximately 795,000 cubic yards of sand on Cameron County and the City of South Padre Island beaches. These restoration projects have reduced the vulnerability of homes and critical infrastructure to the impacts of storm surge.
FEMA estimates that every dollar spent on erosion control and mitigation to preserve wetlands and other natural ecosystems, will provide a return on average of four dollars in cost-savings for the future. Without healthy beaches, dunes and wetlands to protect the coast, there is more day-to-day wear and the impact of major storms and Hurricanes is far more severe.
Current priority areas for restoring the beach/dune system are those dune complexes severely damaged or destroyed by hurricanes along the Gulf shorelines of Galveston Island, Bolivar Peninsula, and Brazoria County.
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The GLO spends millions of dollars a year to address this problem. Below is a map of current projects: note the cluster of project around Galveston Island.
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The map below shows the average coastal erosion/accretion rates in feet per year, for the period 1931 to 2000, for locations within Galveston County. Erosion, as shown in yellow, orange and red, is reported in positive numbers while accretion, shown in green and blue, is reported in negative numbers.
Source: Compiled and distributed by the University of Texas Bureau of Economic Geology 167 CHAMPS ’17: A Hazard Assessment for Texas
4.2: INLAND EROSION
Inland Erosion is the wearing-away of soil or removal of the banks of streams or rivers. It involves the breakdown, detachment, transport, and redistribution of soil particles by forces of water, wind, or gravity. Soil erosion on cropland is of particular interest because of its on-site impacts on soil quality and crop productivity, and its off-site impacts on water quantity and quality, air quality, and biological activity. Erosion is measured as a rate of change in the position or displacement of a river or stream bank over a period of time or the amount of soil removal. Short-term erosion results from periodic flooding and wind. Long-term erosion is a result of repetitive events of this type and of prolonged drought.
Erosion can affect natural and built environments. Impacts depend on topography, soils, farming practices, engineering and construction types and materials. Inland erosion can remove top soil, scour river banks and collapse bridges and roads. It can result in the siltification of lakes and reservoirs, reducing their usefulness as flood control features and as sources of water supply. Inland Erosion is mitigated by improving farming methods, improving construction standards, installing groundwater recharge features and creek channelization. Reservoirs are sometimes dredged to remove silts and soils built-up from inland erosion.
Severe long-term drought can reduce plant coverage and allow significant land erosion by winds – resultant dust clouds can and do cause auto accidents (see drought event description above). In the 1930’s, poor farming methods combined with drought and wind to cause massive inland erosion that has since been called the Dust Bowl. These conditions led to Black Blizzards that terrorized the populous and carried Great Plains top soil east to the Atlantic Ocean. These resulted in massive economic and population losses for the region lasting 20 years or more. The following is extracted from Remembering Black Sunday, 80 Years Later, by Jesse Greenspan. It was published April 14, 2015 on History.com:
When wheat prices rose during World War I, homesteaders descended on the southern Great Plains and began plowing up the native grasses that had historically held the soil in place. ... The good times continued throughout the wet years of the 1920s. But when the Great Depression hit, wheat prices collapsed. To make matters worse, it essentially stopped raining in 1931, the beginning of a drought that would last for the rest of the decade. Suddenly, farms were going under, livestock were starving and enormous quantities of dried-out topsoil were being blown up into the air. According to one federal agency, which counted only the largest of these dust storms, or “black blizzards,” 14 hit in 1932, followed by 38 in 1933.
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… Although the northern Great Plains did not escape punishment, the worst effects came further south in Kansas, Colorado, New Mexico, Oklahoma and Texas. … the constant inhalation of harmful dust particles killed hundreds of people and sickened thousands of others.
The Black Sunday storm approaching Rolla, Kansas In 1934, which researchers now call the single worst drought year of the last millennium in North America, temperatures soared, exceeding 100 degrees every day for weeks on much of the Southern Plains. … After months of brutal conditions, the skies finally cleared by the morning of April 14, 1935, and the winds died down, a rarity on the nearly treeless landscape. … That morning, a cold front moving down from Canada clashed with warm air sitting over the Dakotas. In just a couple of hours, temperatures fell more than 30 degrees and the wind whipped into a frenzy, creating a dust cloud that grew to hundreds of miles wide and thousands of feet high as it headed south. Reaching its full fury in southeastern Colorado, southwestern Kansas and the Texas and Oklahoma panhandles, it turned a sunny day totally dark. … it was the worst black blizzard of the Dust Bowl, lasting longer than the others and covering more ground. Later estimates placed the amount of displaced topsoil at 300,000 tons, some of which flew as far away as the East Coast.
Source: http://www.history.com/news/remembering-black-sunday-80-years-later
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To mitigate further black blizzards and conserve soil, the federal government created the National Soil Conservation Service (now the Nation Resource conservation Service – NRCS) in 1935(?) and the State of Texas created the Texas Sate Soil and Water Conservation board in 1939. In addition to promoting soil conservation through improved farming methods, like contour farming (see below), these organizations are tasked with monitoring soil conditions and tracking soil loss.
In contour farming, the ruts made by the plow run perpendicular rather than parallel to slopes, generally resulting in furrows that curve around hills and are level. This method is known for reducing soil erosion from run-off and for preventing tillage erosion: that is soil movement and erosion produced by the act of tilling a given plot of land.
Every 5 years the NRCS conducts a National Resources Inventory (NRI). The NRI is a statistical survey of natural resource conditions and trends on non-Federal land in the United States. Non-Federal land includes privately owned lands, tribal and trust lands, and lands controlled by state and local governments. The NRI provides nationally consistent statistical data on erosion resulting from water and wind processes on cropland. It uses a variety of tables and maps to document the ongoing state of erosion across the county
One key measure used in the NRI is the Erodibility Index (EI). This index is a numerical expression of the potential of a soil to erode, considering climatic factors and the physical and chemical properties of the soil – the higher the index, the greater is the investment needed to maintain the sustainability of the soil resource base if intensively cropped. Highly Erodible Land (HEL) is defined to have an EI of at least 8.
If a producer has a field identified as highly erodible land, that producer is required to maintain a conservation system of practices that keeps erosion rates at a substantial reduction of soil loss. Fields that are determined not to be highly erodible land are not required to maintain a conservation system to reduce erosion.
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Another measure to be familiar with is the soil Tolerance rate. The soil loss tolerance rate (T) is the maximum rate of annual soil loss that will permit crop productivity to be sustained economically and indefinitely on a given soil. Erosion is considered to be greater than T if either the water erosion or the wind erosion rate exceeds the soil loss tolerance rate.
The two maps below are from the 2015 NRI. They depict water based erosion rates in tons per acer per year in 1982 and 2012. Dramatic changes reflect the success of the erosion management programs.
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The map below is from the 2007 NRI, published in 2012. It shows the nationwide trend of declining soil erosion rates on cropland was mirrored in declining soil erosion in each of the 10 farm production regions. The region identified as the Southern Plains (Texas and Oklahoma) had the biggest decline in wind erosion rates, from 9.9 to 6.2 tons per acre per year-a 37% decline-over the 1998 to 2007 period.
Note the width of the various color bars above (and the numbers written in them). The Southern Plains have the highest annual erosion numbers for every year reported. The NRI reported it this way:
Among all farm production regions, combined water and wind erosion in 2007 was lowest in the Northeast (2.7 tons per acre per year) and highest in the Southern Plains (8.8 tons per acre per year).
It is clear that erosion is not as under control as it could be in Texas.
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The map below shows where erosion exceeded the soil loss tolerance rates nationally based on the 2007 inventory. Each red dot represents 100,000 tons of erosion above the soil loss tolerance rate on Highly Erodible Cropland (HEL. Each green dot represents 100,000 tons of erosion above the soil loss tolerance rate on non-HEL croplands.
The large cluster of red and green dots in the upper plains of DPS Region 5 is clearly a place where more needs to be done to fight erosion. There are also red and green clusters in south Texas (Region 3) that should be of concern.
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4.3: SUBSIDENCE
Subsidence is the gradual settling or sudden sinking of the Earth’s surface due to subsurface movement of earth materials. The level of subsidence ranges from a broad lowering to collapse of land surface. Most causes of subsidence are human- induced. Mining and excessive groundwater removal can lead to aquifer system compaction sinkholes, and more. Areas located above or adjacent to karsts topography have a greater risk of experiencing subsidence. Sudden collapses of surface areas can damage and destroy buildings and infrastructure.
Harris County has the most severe subsidence issues in Texas. This graphic depicts how those issues correlate to the urban footprint in and around the City of Houston.
The study this graphic was in, included the following explanation: Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained silt and clay layers. Kasmarek, M.C., Ramage, J.K., Houston, N.A., Johnson, M.R., and Schmidt, T.S., 2015, Water- level altitudes 2015 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973–2014 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas (ver. 1.1, October 2015): U.S. Geological Survey Scientific Investigations Map 3337, pamphlet, 16 sheets, scale 1:100,000, https://dx.doi.org/10.3133/sim3337.
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The graphic below labels the subsidence contours above and shows where subsidence issues extend beyond Houston into Galveston and Fort Bend Counties.
As a result of reduced elevation, loss of wetlands, and the loss of other natural coastal protective features, subsidence increases coastal communities’ risk to inundation and saltwater intrusion from storm surge. Subsidence creates and exacerbates erosion and flooding along the shoreline that can threaten structures and critical infrastructure, including hurricane evacuation routes.
Regulation of groundwater interaction (draw down and recharge) are a key to managing this ongoing issue. In May of 1975, the Texas Legislature created the Harris-Galveston Subsidence District (HGSD), as a regulatory agency to "end subsidence", and provided HGSD the authority to restrict groundwater withdrawals. Fort Bend County has its own: the Fort Bend Subsidence District (FBSD). These entities study causes and impacts of subsidence so that they can better plan for and mitigate future risks.
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The graphic below is from the FBSD Science and Research Plan – adopted in 2015. It shows the depth from sea-level of the various aquifers and confining units along a line that crosses four counties, from Grimes to the northwest to Galveston to the southeast (see inset map). Subsidence in this region is primarily associated with the drawdown of groundwater in the Chicot and Evangeline aquifers and the associated compaction of their structure. Recent advances in water-well technologies are making accessing the third aquifer (the Jasper) more economically viable. One of the questions currently being studied is the potential impact of such use on subsidence in the area.
Hydrogeologic section A–A´ of the Gulf Coast aquifer system in Grimes, Montgomery, Harris, and Galveston Counties, Texas (modified from Baker, 1979, fig. 4).
Other study questions include local surface/ground water interactions (including the potential usefulness of groundwater recharge features) and investigation of means to reduce reliance on groundwater through development of surface alternatives.
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The material below was extracted from Chapter 7of the Texas Water Development Board Report 365: Aquifers of the Gulf Coast of Texas, Published in 2006. It was written by Thomas A. Mitchel, an employee of the Harris-Galveston Subsidence District. It describes the process by which subsidence occurred in this are and how it was, and is, being mitigated.
In Harris County and the surrounding counties (Figure 7-2), generally referred to as the Greater Houston Area, groundwater was withdrawn from the Chicot and Evangeline aquifers as the demands rose rapidly. The results of the groundwater withdrawals led to declines in the water levels of both aquifers. From 1943 to 1977, the Chicot aquifer experienced water-level declines of as much as 200 feet, while the Evangeline aquifer had declined as much as 300 feet
Figure 7-2. Map of Harris and surrounding counties, showing the boundaries of the subsidence districts.
… With the large amount of groundwater that was being pumped from underground throughout most of the 20th century, water levels were declining, but groundwater was also literally being “sucked” from the layers of clays within the aquifers. The clays compacted due to the reduced internal pressure in the clays and the overburden, resulting in land-surface subsidence.
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…In 1975, the 64th Texas Legislature created the Harris-Galveston Coastal Subsidence District … The purpose of the District has always remained as the need to regulate groundwater withdrawals as they relate to land- surface subsidence in Harris and Galveston counties. In 1990, the Legislature created the Fort Bend Subsidence District, and the two Districts cooperate on an annual basis to halt subsidence within Fort Bend, Galveston, and Harris counties. …The District immediately began a permitting effort to require permits for non-private household water wells and called for the installation of meters on virtually all permitted wells.
… In 1985, after a number of years of collecting data and studying the relationship between groundwater and subsidence, the District adopted the first mandated groundwater reductions. …. The 1985 Plan worked well in the more coastal areas of the District. Subsidence rates slowed dramatically in southeastern Harris County and were halted throughout most of Galveston County
… Water demands were increasing with the growing population in the remaining parts of Harris County. …The District’s 1999 Regulatory Plan has been very successful. Groundwater withdrawals have already begun to decline (by 2006).
…The Harris-Galveston Subsidence District … has permitted over 10,000 water wells within its two counties, aided in the creation and operation of the Fort Bend Subsidence District, assisted in the monitoring of more than 500 water wells annually, conducted three major first-order benchmark re-leveling from stable inland elevations, led in the development of new technologies such as GPS to measure subsidence, been involved with six generations of groundwater models, and worked and reworked four major regulatory plans. The District has been responsible for the development of the regulations which required the conversion of millions of gallons daily from groundwater sources to surface water sources. The historical cost of the District’s regulations in today’s dollars would surely be in the billions. The cost of the District’s regulations to the residents of today and tomorrow will be even greater.
Source: http://www.twdb.texas.gov/publications/reports/numbered_reports/doc/ R365/Report365.asp
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The struggle to prevent future subsidence in the Houston area is on-going. The black circle on the map below surrounds the area of restricted flow through the aquifer system that was created by excessive pumping. The challenge going forward is to prevent the expansion of this area and future subsidence, by balancing groundwater pumping with aquifer recharge.
Source: Hydrogeology and Simulation of Groundwater Flow and Land-Surface Subsidence in the North Part of the Gulf Coast Aquifer System, Texas, 1891-2009, USGS, Nov 2013. One of the things that complicates aquifer recharge is the amount of impervious cover. The image to the right, from a Houston Advanced Research Center “OUR BLOG” post of June 23, 2015 shows that most of the Harris County has some type of impervious cover
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Sinkholes
A sinkhole is a type of subsidence. According to an article in the Texas Parks & Wildlife online:
“A sinkhole is a natural depression that's formed when subsurface limestone, salt or gypsum is slowly eroded away by groundwater. As surface water infiltrates the soil, it percolates downward and moves deeper into the soil. Over time, the water eats away at the rock layer until voids, or caves, form in the rock. As these voids grow, ultimately the spaces between the rocks become too big and the weight of the earth on top of the rock causes the chamber to collapse.
Natural sinkholes most commonly form in the karst regions of Texas. Karst is an area of irregular limestone in which erosion has produced fissures, sinkholes, underground streams and caverns. In Texas, high concentrations of karst rock occur in the soluble limestone areas of the Hill Country and the gypsum-rich Rolling Plains of northwest Texas.
It is possible, however, for unnatural sinkholes to form. In urban areas, water main breaks can erode the subsoil and cause the earth above to cleave.” http://www.tpwmagazine.com/archive/2008/jan/ed_5/
The map, from the USGS, below shows areas of the United States where rock types that are susceptible to dissolution in water occur. In these areas underground cavities can form and sinkholes happen. These rock types are evaporites (salt, gypsum, and anhydrite) and carbonates (limestone and dolomite).
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Examples of sinkholes that have affected communities include Wink sinkholes 1 and 2 in in Winkler County which occurred in 1980 and Daisetta, Liberty County, which occurred in 2008.
To the right is a high-resolution digital elevation model of Wink Sink 2. This was created from topographic LIDAR data acquired during an airborne survey conducted by the Bureau of Economic Geology in November 2013 (Image by J. Andrews).
West and Central Texas have also experienced land subsidence perhaps due to oil exploration or created by the erosion of subsurface limestone, salt or gypsum by groundwater. The following is an extract from the Alamo Area Council of Governments Regional Mitigation Action Plan Update from April 2012:
Sinkholes are of interest to Central and Western Texas because they are one of the predominant landform features of those areas of the state. Their development may be sudden and may result in property damage or loss of life. Sinkholes can vary greatly in both diameter and depth. Recorded occurrences have ranged from a few feet to more than 2,000 feet, both in depth and diameter. Portions of Gillespie, Kerr, Bandera, Medina, Frio, Comal, Bexar and Atascosa counties are located in karst regions, which are susceptible to cave and sinkhole development due to the geology and geomorphology of the area. However, limited property damage or loss of life due to sinkholes in these areas has been recorded. Given the geologic composition of the area, the planning area can expect to experience a variety of sinkholes, in varying depths and diameters.
Source: https://www.aacog.com/DocumentCenter/Home/View/4309
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Below is a list of historically significant land subsidence occurrences in Texas
Date Affected Area Remarks
1943-1964 Fort Bend County The eastern one-third of the county has experienced a drop that exceeded one foot while water levels dropped more than 100 feet during this period.
June 3, 1980 Winkler County The first of two sinkholes that appeared near Wink, Texas measured 120 yards long and 100 yards wide.
June 2000 Houston- Early oil and gas production and a long Galveston area history of ground-water pumpage in the Houston-Galveston area, Texas, have created severe and costly coastal flooding hazards and affected a critical environmental resource—the Galveston Bay estuary.
May 21, 2002 Winkler County A second sinkhole appeared approximately one mile from the original Wink sinkhole. It grew much larger covering an area greater than two football fields.
May 7, 2008 Liberty County In Daisetta, Texas, a huge sinkhole measuring approximately 600 feet long and 525 feet wide caused a section of highway 77 to close after it was determined that parts of the roadway may have subsided by five inches.
Sources: Gabrysch, R. K., 1970, Land-surface subsidence in the Houston- Galveston region, Texas: Internet symposium on land subsidence, Tokyo, Japan, 1969, Proc. Dec. 2000, United States Geological Survey. www.co.liberty.tx.us/default.aspx?Liberty_county/sinkhole. www.rootsweb.ancestry,.com/txwinkle/midland-paper
While groundwater withdrawals have been restricted over the last forty years in the coastal area, subsidence may continue to develop from other types of below ground withdrawals or from natural forces. Major occurrences of subsidence events over the five years covered by this mitigation plan are unlikely.
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4.4: EARTHQUAKES
An earthquake is a sudden release of energy created by a movement along fault lines in the earth’s crust. Earthquakes produce three type of energy waves:
Primary (P) waves have a push-pull type of vibration. Secondary (S) waves have a side-to-side type of vibration. Both P and S waves travel deep into Earth, reflecting off the surfaces of its various layers. S waves cannot travel through the liquid outer core. Surface (L) waves—named after the nineteenth-century British mathematician A.E.H. Love—travel along Earth's surface, causing most of the damage of an earthquake. The total amount of energy released by an earthquake is measured on the Richter scale. Each increase by 1 corresponds to a tenfold increase in strength. Earthquakes above 7 on the Richter scale are considered severe. The famous earthquake that flattened San Francisco in 1906 had a magnitude of 7.8.
Source: "earthquake". The American Heritage® Science Dictionary. Houghton Mifflin Company. 20 Oct. 2017.
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The level of damage that results from an earthquake depends on the extent and duration of the shaking. Most earthquake-related property damage and deaths are caused by the failure and collapse of structures due to ground shaking. An earthquake with magnitude 3 may do no more than startle people and rattle dishes within a one-square mile region. A magnitude 7 might be felt by people statewide and could do significant damage to buildings, bridges, and dams over a considerable region.
Scientists determine an earthquake's magnitude by measuring the amplitude of ground motion as recorded on a seismograph, and then correcting the measurement to account for the effects of distance from the epicenter (the place on the earth’s surface directly above the seismic focus). The magnitude scale is a 'power of ten' scale; thus if a magnitude 3.8 caused ground motion of 1/10 inch at a particular location, a 4.8 at the same epicenter would cause ground motion of 1 inch, and a 5.8 would cause ground motion of 10 inches. The table below list by magnitude what types of effects can be expected and the general frequency of these events worldwide in any given year.
While each earthquake has only one magnitude, different location experience different intensities, since earthquake damage becomes less severe as one moves away from the epicenter. Usually, most of the damage done by an earthquake occurs in the regions nearest the epicenter which have the highest intensities. While intensity depends strongly on factors such as soil properties, in most cases earthquakes with larger magnitudes have higher maximum intensities.
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Scientists use the Modified Mercalli Intensity (MMI) scale to describe how strong the motion is at a particular location. The MMI is a number between one and twelve, expressed as a Roman numeral so that the number won't be confused with magnitude.
The Modified Mercalli Intensity Scale (MMI) MMI What people feel, or what damage occurs. Not felt except by a very few people under special conditions. I Detected mostly by instruments. II Felt by a few people, especially those on the upper floors of buildings. Suspended objects may swing. III Felt noticeably indoors. Standing automobiles may rock slightly. IV Felt by many people indoors, by a few outdoors. At night, some people are awakened. Dishes, windows, and doors rattle. V Felt by nearly everyone. Many people are awakened. Some dishes and windows are broken. Unstable objects are overturned. VI Felt by everyone. Many people become frightened and run outdoors. Some heavy furniture is moved. Some plaster falls. VII Most people are alarmed and run outside. Damage is negligible in buildings of good construction, considerable in buildings of poor construction. VIII Damage is slight in specially designed structures, considerable in ordinary buildings, great in poorly built structures. Heavy furniture is overturned. IX Damage is considerable in specially designed buildings. Buildings shift from their foundations and partly collapse. Underground pipes are broken. X Some well-built wooden structures are destroyed. Most masonry structures are destroyed. The ground is badly cracked. Considerable landslides occur on steep slopes. XI Few, if any, masonry structures remain standing. Rails are bent. Broad fissures appear in the ground. XII Virtually total destruction. Waves are seen on the ground surface. Objects are thrown into the air.
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The seismic hazard risk map below indicates the 2% probability for Peak Ground Acceleration of various intensities over 50 years in Texas (% g, where g is defined as the ground motion of 1g = 980.5 cm/s/s). Texas is at a relatively very low risk of earthquake damage. While there are exceptions - like in the El Paso area, most of Texas has a less than 2% probability of having a very weak ground shaking event over 50 years. The risk in El Paso (highlighted) is relatively (13 -15% over 50 years)
Source: United States Geological Survey (USGS) Earthquake Hazards Program.
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Texas earthquake hazard is very small in comparison to many other states, including California, Missouri, Montana, South Carolina and Washington. Our biggest threat appears to be from the New Madrid fault system in Missouri, a system powerful enough to pose a risk to north Texas from very large earthquakes (magnitude 7 or above) which might occur along the New Madrid fault along the border of Missouri and Tennessee. The New Madrid fault line system is circled on the map below:
http://www.hsdl.org/?view&did=8324
One reason Texas earthquake risk is so low has to do with the predominance of limestone in the Texas crust (or lithosphere). Limestone tends to crumble under force and does not build-up tension the way harder materials do. Crumbling also reduces force-wave propagation. The net result is that most parts of Texas tend to have fewer earthquakes than other places in the county and the ones they do have tend to produce less shaking and do less damage.
El Paso and the Panhandle are two areas of Texas that can expect earthquakes with magnitudes of about 5.5-6.0 to occur every 50-100 years. Even larger earthquakes are possible there. In southcentral Texas the hazard is generally low, but small earthquakes can occur, including some that may be triggered by oil or gas production.
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In September of 2016 the Dallas Morning News reported (in an opinion piece):
In the last eight years, Texas has experienced more than 150 earthquakes. Startlingly, these earthquakes appear to be man-made, caused by injecting wastewater from oil and gas production into disposal wells. Numerous studies have found that pumping such huge volumes of wastewater into the ground can cause existing faults to move, triggering earthquakes.
Frequent earthquakes are a new problem in Texas, coinciding with the growth of fracking -- and massive volumes of fracking wastewater requiring disposal.
…Researchers at the University of Texas have found that an average of 12 earthquakes of a magnitude 3.0 or higher now shake Texas every year. Recent earthquake activity is concentrated in North Texas, in the middle of the Barnett Shale, a hotspot for fracking and wastewater disposal wells. Earthquakes were reported near the DFW International Airport beginning in 2008 -- the first reported earthquakes in the region since 1950 -- while Cleburne experienced 50 quakes in 2009 and 2010.
In the first few years of the fracking boom, from 2005 to 2011, the amount of wastewater injected into disposal wells in Texas increased 70-fold. Of the magnitude 3.0 and greater earthquakes Texas has experienced since 2008, many have occurred within one or two miles of high-volume disposal wells.
Source: https://www.dallasnews.com/opinion/commentary/2016/09/07/texas- -energy-regulators-halt-injection-activity-causes-earthquakes
In their Report on House Bill 2 (2016–17): Seismic Monitoring and Research in Texas, from December 1, 2016, the University of Texas Bureau of Economic Geology included an update on a research project entitled “Theoretical Analysis of Controls on Size of Earthquakes Induced by Fluid Injection” (PI: Jon Olson, PGE UT- Austin), uses the following language to describe this phenomena:
The causality of earthquakes induced by wastewater injection is likely due to the interaction of fluid flow with existing faults. Wastewater injection increases underground fluid pressure, and increased fluid pressure reduces frictional resistance on the fault, possibly inducing sliding displacement. Whether fault slip generates measurable seismicity depends on fluid pressure and stress factors (initial reservoir pressure, in situ stress, rate of fluid pressure increase, and so on), as well as on fault-plane characteristics (orientation relative to principal stress directions, fault strength, weakening and strengthening of the fault during rupture, and so on) (Terzaghi, 1943; Barton and others, 1995; Ellsworth, 2013; National Research Council, 2013; Dieterich and others, 2015)
Source: http://www.beg.utexas.edu/files/texnet/docs/TexNet-Report-2016.pdf
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The map below shows historic earthquake events in Texas between 1973 and 2012 by magnitude. El Paso County is highlighted. The collection of events reported in the Dallas-Fort Worth are, in deep east Texas and in the eastern high plane appear to not be explained by the earthquake risk maps above.
Source: United States Geological Survey (USGS) Earthquake Hazards Program
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The largest recorded earthquake in Texas occurred in 1931 in in Jeff Davis County near the City of Valentine (magnitude 5.8/MM Intensity-VIII). Historical earthquake event are listed on the tables below.
Historically Significant Earthquake Occurrences
Date Affected Area Remarks
October 22, 1882 Sherman, Texas Heavy machinery vibrated, Magnitude: 5.6 chimneys crumbled, and movable objects overturned January 5, 1887 Bastrop County Shocks felt over 4,600 square Magnitude: 4.1 kilometers
May 3, 1887 West Texas, including El Earthquake originated in Sonora, Paso and Fort Davis Mexico Magnitude: 7.4
July 30, 1925 Texas Panhandle Shocks covered 518,000 square Magnitude: 5.4 kilometers reaching from Roswell, New Mexico to Leavenworth, Kansas August 16, 1931 Brewster, Jeff Davis, Severe damage was reported at Culberson, and Presidio Valentine, where all buildings Counties Magnitude: 6.0 except wood-frame houses were damaged severely and all brick chimneys toppled or were damaged April 9. 1932 Mexia-Wortham, Texas The shock was also felt in Magnitude: 4.0 Coolidge, Currie, Groesbeck, Hillsboro, Teague and Richland
April 11, 1934 Northeastern Texas The tremor was most distinctly Magnitude: 4.2 felt at Arthur City, Chicota and Powderly June 19, 1936 Texas Panhandle near Effects were noted at Gruver, Borger, Texas Magnitude: White Deer, and Whittenberg, 5.0 Texas, Kenton, Oklahoma, and Elkhart, Kansas
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Historically Significant Earthquake Occurrences (continued)
March 11, 1948 Texas Panhandle The strongest effects (VI) were Magnitude: 5.2 reported from Amarillo, Channing, Dalhart, Electric City, Panhandle, Perico, and Perryton
April 9, 1952 Central Oklahoma Shocks felt from North Texas to Magnitude: 5.5 Austin
March 19, 1957 Texas area bordering Effects were felt in Gladewater, portions of Arkansas and Diana, Elkhart, Marshall, Louisiana Magnitude: 4.7 Nacogdoches and Troup
April 23-28, 1964 Texas-Louisiana border The shock was also felt at region near Hemphill, Bronson, Geneva, Milam and Texas Magnitude: 4.4 Pineland
April 9, 1993 Atascosa County Campellton home knocked off Magnitude: 4.3 foundation. Natural-gas processing plant shut down April 14, 1995 Brewster County Broken water and gas mains, Magnitude: 5.7 cracked walls, and small fires erupted following aftershocks November 5, 2011 Oklahoma City and Tulsa Tremors were felt into North Magnitude: 5.6 Texas
Sources: Principally, the U.S. Geological Survey and the Institute for Geophysics at the University of Texas at Austin. Also, previous Texas Almanacs.
Slight earthquakes do occur with frequency in Texas. Higher magnitude earthquakes that could cause damage, have occurred about every 10 years for that reason, reoccurrence of this hazard possible but not likely.
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Appendix 1: Weather-Related Hazard Summaries
The following six sub-sections include tables and maps generated from the National Center of Environmental Information (NCEI) data used in this assessment. These provide summary information for historic and forecast impacts of the twelve weather-related hazards for each of the DPS Regions. This appendix was prepared for those who want to focus in on individual DPS regions and to compare them one to another or to the state information provided in the report. This material is presented with limited narrative. Readers are invited to review Section 3 of the report to see full treatment of the various weather-related hazards and related topics.
Each subsection includes one table describing historical weather-related impacts and then one table and one map describing forecasted weather-related impacts. The tables and maps include:
Table 1: Weather Related Hazard Impacts: 1996 – 2016 * A three part table reporting base period (1996- 2016) information, including: 1. Total impacts over the 21 years in each of the 12 hazards 2. The average annual impacts of each hazard/impact combination; and 3. The percent of the total regional impacts for each impact type.
Table 2: Weather Related Hazard Impact Forecast: 2019 – 2023 * A three part table reporting forecast period (2019-23) information, including: 1. Total forecast impacts over the 5 years in each of the 12 hazards 2. The average annual forecast impact for each hazard/impact combination; and 3. The percent of the total of forecast regional impacts for each impact type.
Map 1: Weather-Related Dollar Loss Forecast: 2019 - 2023 These are region specific maps showing the total property and crop dollar loss forecasts by county. They include inset tables reporting the highest-loss counties and their forecast dollar losses – these are also labeled on the map. In regional maps, colors indicate losses relative to other counties within that Region. Each color represents approximately 20 % of the counties in the region.
The state weather-related hazard summaries in Section 3.0 of this report provide the overall statewide perspective that these regional summaries fit in to.
* Hazards are listed in tables 1 and 2 in order of the total damage they either did or are forecast to do – this order changes slightly between periods.
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A1.1: REGION 1 WEATHER-RELATED HAZARD SUMMARY Region 1 had 15% of the statewide property losses over the base period and 5 % of the statewide crop losses. It had more Hailstorm, Tornado, Winter Weather Lightning and Heat Losses than any other region. Table A1.1.1: Region 1 Weather Related Hazard Impacts: 1996 - 2016 21-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) HURRICANE TS/D 9,075,320 2 9,075,320 DROUGHT 15,128,672 820,386,729 835,515,401 HAIL 3,999,702,350 112,325 1 11 3,999,814,675 S. COASTAL FLOOD RIVERINE FLOODING 1,313,833,015 30,163,878 80 50 1,343,996,893 TORNADO 1,471,920,689 277,786 31 1,003 1,472,198,475 S. T-STORM-WIND 146,001,024 132,485 18 126 146,133,509 WILDFIRE 72,215,570 5,215,662 6 30 77,431,232 WINTER WEATHER 349,893,852 36 966 349,893,852 LIGHTNING 36,372,256 11 49 36,372,256 COLD 1,938,183 14 1,938,183 HEAT 212,984 144 935 212,984 Total 7,416,293,915 856,288,865 341 3,172 8,272,582,780 Average Annual Impacts (21-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual HURRICANE TS/D 432,158 0 432,158 DROUGHT 720,413 39,066,035 39,786,448 HAIL 190,462,017 5,349 0 2 190,467,365 S. COASTAL FLOOD RIVERINE FLOODING 62,563,477 1,436,375 16 10 63,999,852 TORNADO 70,091,461 13,228 6 201 70,104,689 S. T-STORM-WIND 6,952,430 6,309 4 25 6,958,739 WILDFIRE 3,438,837 248,365 1 6 3,687,202 WINTER WEATHER 16,661,612 7 193 16,661,612 LIGHTNING 1,732,012 2 10 1,732,012 COLD 92,294 3 92,294 HEAT 10,142 29 187 10,142 Total 353,156,853 40,775,660 68 634 393,932,513 Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses HURRICANE TS/D 0.1% 0.1% 0.1% DROUGHT 0.2% 95.8% 10.1% HAIL 53.9% 0.0% 0.3% 0.3% 48.4% S. COASTAL FLOOD RIVERINE FLOODING 17.7% 3.5% 23.5% 1.6% 16.2% TORNADO 19.8% 0.0% 9.1% 31.6% 17.8% S. T-STORM-WIND 2.0% 0.0% 5.3% 4.0% 1.8% WILDFIRE 1.0% 0.6% 1.8% 0.9% 0.9% WINTER WEATHER 4.7% 10.6% 30.5% 4.2% LIGHTNING 0.5% 3.2% 1.5% 0.4% COLD 0.0% 4.1% 0.0% HEAT 0.0% 42.2% 29.5% 0.0% Total 100% 100% 100% 100% 100% 194 CHAMPS ’17: A Hazard Assessment for Texas
Forecasted property losses for Region 1, are expected to average $386 million a year over the forecast period. This is $33 million higher than base period average. Table A1.1.2: Region 1 Weather Related Impact Forecast: 2019 - 2023
5-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) S. COASTAL FLOOD HURRICANE TS/D 2,759,243 1 2,759,243 DROUGHT 4,054,762 206,973,666 211,028,428 HAIL 1,056,441,753 26,744 0 3 1,056,468,497 RIVERINE FLOODING 343,763,513 7,609,982 21 13 351,373,495 TORNADO 374,502,330 66,140 8 257 374,568,470 WILDFIRE 33,864,213 2,377,085 3 14 36,241,298 S. T-STORM-WIND 36,829,691 31,544 5 32 36,861,235 WINTER WEATHER 69,909,469 8 211 69,909,469 LIGHTNING 9,474,662 3 12 9,474,662 COLD 421,718 3 421,718 HEAT 61,684 43 278 61,684 Total 1,932,083,036 217,085,161 94 821 2,149,168,197
Average Annual Forecasted Impacts (5-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual S. COASTAL FLOOD HURRICANE TS/D 551,849 0 551,849 DROUGHT 810,952 41,394,733 42,205,686 HAIL 211,288,351 5,349 0 1 211,293,699 RIVERINE FLOODING 68,752,703 1,521,996 4 3 70,274,699 TORNADO 74,900,466 13,228 2 51 74,913,694 WILDFIRE 6,772,843 475,417 1 3 7,248,260 S. T-STORM-WIND 7,365,938 6,309 1 6 7,372,247 WINTER WEATHER 13,981,894 2 42 13,981,894 LIGHTNING 1,894,932 1 2 1,894,932 COLD 84,344 1 84,344 HEAT 12,337 9 56 12,337 Total 386,416,607 43,417,032 19 164 429,833,639
Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses S. COASTAL FLOOD HURRICANE TS/D 0.1% 0.1% 0.1% DROUGHT 0.2% 95.3% 9.8% HAIL 54.7% 0.0% 0.3% 0.3% 49.2% RIVERINE FLOODING 17.8% 3.5% 22.7% 1.6% 16.3% TORNADO 19.4% 0.0% 8.5% 31.3% 17.4% WILDFIRE 1.8% 1.1% 3.1% 1.7% 1.7% S. T-STORM-WIND 1.9% 0.0% 5.0% 3.9% 1.7% WINTER WEATHER 3.6% 8.4% 25.7% 3.3% LIGHTNING 0.5% 3.0% 1.5% 0.4% COLD 0.0% 3.4% 0.0% HEAT 0.0% 45.7% 33.9% 0.0% Total 100% 100% 100% 100% 100%
195 CHAMPS ’17: A Hazard Assessment for Texas
The map below shows the forecast losses for counties in Region 1. The inset table reports the total dollar loss forecast for the highest-loss counties and those county’s percentages of the overall regional forecast. From this table you can see that Dallas, Tarrent, Navarro, Colin and Denton counties make of 71% of the Region 1’s forecast losses.
Map A1.1.1: Region 1 Weather-Related Dollar Loss Forecast: 2019 - 2023
196 CHAMPS ’17: A Hazard Assessment for Texas
A1.2: REGION 2 WEATHER-RELATED HAZARD SUMMARY Region 2 had 57% of the statewide property losses over the base period and 4% of the statewide crop losses. It had more Hurricane TS/D and Severe Coastal Flooding losses than any other region. Table A1.2.1: Region 2 Weather Related Hazard Impacts: 1996 - 2016 21-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) HURRICANE TS/D 16,308,035,256 55 2,427 16,308,035,256 DROUGHT 32,336,396 500,014,063 532,350,459 HAIL 84,362,539 10,421,568 94,784,107 S. COASTAL FLOOD 10,354,386,036 13 10,354,386,036 RIVERINE FLOODING 391,497,037 2,884,436 52 6 394,381,473 TORNADO 169,160,963 5,417,106 6 208 174,578,069 S. T-STORM-WIND 185,217,207 73,084,644 14 85 258,301,851 WILDFIRE 12,412,872 3,515,060 15,927,932 WINTER WEATHER 28,759,606 6 20 28,759,606 LIGHTNING 15,904,409 1,028 28 133 15,905,437 COLD 1,558,784 2 1,558,784 HEAT 150 2 Total 27,583,631,105 595,337,905 326 2,881 28,178,969,010 Average Annual Impacts (21-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual HURRICANE TS/D 776,573,107 11 485 776,573,107 DROUGHT 1,539,828 23,810,193 25,350,022 HAIL 4,017,264 496,265 4,513,529 S. COASTAL FLOOD 493,066,002 3 493,066,002 RIVERINE FLOODING 18,642,716 137,354 10 1 18,780,070 TORNADO 8,055,284 257,957 1 42 8,313,241 S. T-STORM-WIND 8,819,867 3,480,221 3 17 12,300,088 WILDFIRE 591,089 167,384 758,473 WINTER WEATHER 1,369,505 1 4 1,369,505 LIGHTNING 757,353 49 6 27 757,402 COLD 74,228 0 74,228 HEAT 30 0 Total 1,313,506,243 28,349,424 65 576 1,341,855,667 Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses HURRICANE TS/D 59.1% 16.9% 84.2% 57.9% DROUGHT 0.1% 84.0% 1.9% HAIL 0.3% 1.8% 0.3% S. COASTAL FLOOD 37.5% 4.0% 36.7% RIVERINE FLOODING 1.4% 0.5% 16.0% 0.2% 1.4% TORNADO 0.6% 0.9% 1.8% 7.2% 0.6% S. T-STORM-WIND 0.7% 12.3% 4.3% 3.0% 0.9% WILDFIRE 0.0% 0.6% 0.1% WINTER WEATHER 0.1% 1.8% 0.7% 0.1% LIGHTNING 0.1% 0.0% 8.6% 4.6% 0.1% COLD 0.0% 0.6% 0.0% HEAT 46.0% 0.1% Total 100% 100% 100% 100% 100% 197 CHAMPS ’17: A Hazard Assessment for Texas
Forecasted property losses for Region 2, are expected to average $2.2 billion a year over the forecast period. This is $900 million higher than base period average Table A1.2.2: Region 2 Weather Related Impact Forecast: 2019 - 2023
5-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) S. COASTAL FLOOD 5,606,970,326 7 5,606,970,326 HURRICANE TS/D 5,141,052,377 18 776 5,141,052,377 DROUGHT 8,678,269 126,147,511 134,825,780 HAIL 22,158,016 2,481,326 24,639,342 RIVERINE FLOODING 102,585,521 727,708 14 2 103,313,229 TORNADO 42,755,123 1,289,787 1 54 44,044,910 WILDFIRE 5,796,468 1,602,020 7,398,488 S. T-STORM-WIND 46,217,735 17,401,106 4 21 63,618,841 WINTER WEATHER 5,884,263 1 4 5,884,263 LIGHTNING 4,131,918 245 7 33 4,132,163 COLD 331,082 0 331,082 HEAT 46 1 Total 10,986,561,099 149,649,703 99 891 11,136,210,802
Average Annual Forecasted Impacts (5-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual S. COASTAL FLOOD 1,121,394,065 1 1,121,394,065 HURRICANE TS/D 1,028,210,475 4 155 1,028,210,475 DROUGHT 1,735,654 25,229,502 26,965,156 HAIL 4,431,603 496,265 4,927,868 RIVERINE FLOODING 20,517,104 145,542 3 0 20,662,646 TORNADO 8,551,025 257,957 0 11 8,808,982 WILDFIRE 1,159,294 320,404 1,479,698 S. T-STORM-WIND 9,243,547 3,480,221 1 4 12,723,768 WINTER WEATHER 1,176,853 0 1 1,176,853 LIGHTNING 826,384 49 1 7 826,433 COLD 66,216 0 66,216 HEAT 9 0 Total 2,197,312,220 29,929,941 20 178 2,227,242,160
Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses S. COASTAL FLOOD 51.0% 7.1% 50.3% HURRICANE TS/D 46.8% 17.8% 87.1% 46.2% DROUGHT 0.1% 84.3% 1.2% HAIL 0.2% 1.7% 0.2% RIVERINE FLOODING 0.9% 0.5% 14.3% 0.2% 0.9% TORNADO 0.4% 0.9% 1.5% 6.1% 0.4% WILDFIRE 0.1% 1.1% 0.1% S. T-STORM-WIND 0.4% 11.6% 3.6% 2.4% 0.6% WINTER WEATHER 0.1% 1.3% 0.5% 0.1% LIGHTNING 0.0% 0.0% 7.4% 3.7% 0.0% COLD 0.0% 0.4% 0.0% HEAT 46.6% 0.1% Total 100% 100% 100% 100% 100% 198 CHAMPS ’17: A Hazard Assessment for Texas
The map below shows the forecast losses for counties in Region 2. The inset table reports the total dollar loss forecast for the highest-loss counties and those county’s percentages of the overall regional forecast. Total dollar losses in Harris and Galveston are forecast to be $7.8 billion. That is 69% of Region 2’s forecast losses and 38% of the total forecast losses statewide. The continued increase in losses forecast for these counties is due to the continued expected population and building growth combined with expected growth in damage related to Hurricane TS/D and Severe Coastal Flooding.
Map A1.2.1: Region 2 Weather-Related Dollar Loss Forecast: 2019 - 2023
199 CHAMPS ’17: A Hazard Assessment for Texas
A1.3: REGION 3 WEATHER-RELATED HAZARD SUMMARY
Region 3 had 5% of the statewide property losses over the base period and 5% of the statewide crop losses. Table A1.3.1: Region 3 Weather Related Hazard Impacts: 1996 - 2016 21-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) HURRICANE TS/D 1,184,538,362 2,378,470 4 1,186,916,832 DROUGHT 91,790,648 268,002,805 359,793,453 HAIL 308,135,247 1,524,207 1 13 309,659,454 S. COASTAL FLOOD 9,957,716 9,957,716 RIVERINE FLOODING 341,117,981 473,995,768 27 357 815,113,749 TORNADO 228,385,440 138,818 8 47 228,524,258 S. T-STORM-WIND 107,525,279 1,465,743 14 108,991,022 WILDFIRE 15,622,528 60,945 8 15,683,473 WINTER WEATHER 10,413,863 11,893,161 4 3 22,307,024 LIGHTNING 2,386,867 2 7 2,386,867 COLD 1,831,740 1,831,740 HEAT 14 2 Total 2,299,873,931 761,291,657 56 455 3,061,165,588 Average Annual Impacts (21-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual HURRICANE TS/D 56,406,589 113,260 1 56,519,849 DROUGHT 4,370,983 12,762,038 17,133,022 HAIL 14,673,107 72,581 0 3 14,745,688 S. COASTAL FLOOD 474,177 474,177 RIVERINE FLOODING 16,243,713 22,571,227 5 71 38,814,940 TORNADO 10,875,497 6,610 2 9 10,882,108 S. T-STORM-WIND 5,120,251 69,797 3 5,190,049 WILDFIRE 743,930 2,902 2 746,832 WINTER WEATHER 495,898 566,341 1 1 1,062,239 LIGHTNING 113,660 0 1 113,660 COLD 87,226 87,226 HEAT 3 0 Total 109,517,806 36,251,984 11 91 145,769,790 Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses HURRICANE TS/D 51.5% 0.3% 0.9% 38.8% DROUGHT 4.0% 35.2% 11.8% HAIL 13.4% 0.2% 1.8% 2.9% 10.1% S. COASTAL FLOOD 0.4% 0.3% RIVERINE FLOODING 14.8% 62.3% 48.2% 78.5% 26.6% TORNADO 9.9% 0.0% 14.3% 10.3% 7.5% S. T-STORM-WIND 4.7% 0.2% 3.1% 3.6% WILDFIRE 0.7% 0.0% 1.8% 0.5% WINTER WEATHER 0.5% 1.6% 7.1% 0.7% 0.7% LIGHTNING 0.1% 3.6% 1.5% 0.1% COLD 0.2% 0.1% HEAT 25.0% 0.4% Total 100% 100% 100% 100% 100%
200 CHAMPS ’17: A Hazard Assessment for Texas
Forecasted property losses for Region 3, are expected to average $130 million a year over the forecast period. This is $ 21 million higher than base period average Table A1.3.2: Region 3 Weather Related Impact Forecast: 2019 - 2023
5-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) S. COASTAL FLOOD 5,173,604 5,173,604 HURRICANE TS/D 359,623,196 692,919 1 360,316,115 DROUGHT 23,204,315 67,613,872 90,818,187 HAIL 78,061,898 362,906 0 3 78,424,805 RIVERINE FLOODING 89,824,911 119,583,409 7 92 209,408,320 TORNADO 58,887,286 33,052 2 12 58,920,338 WILDFIRE 7,560,048 27,776 4 7,587,824 S. T-STORM-WIND 27,143,618 348,986 4 27,492,605 WINTER WEATHER 2,103,476 2,412,389 1 1 4,515,865 LIGHTNING 607,714 1 2 607,714 COLD 388,206 388,206 HEAT 4 1 Total 652,190,066 191,463,516 15 118 843,653,582
Average Annual Forecasted Impacts (5-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual S. COASTAL FLOOD 1,034,721 1,034,721 HURRICANE TS/D 71,924,639 138,584 0 72,063,223 DROUGHT 4,640,863 13,522,774 18,163,637 HAIL 15,612,380 72,581 0 1 15,684,961 RIVERINE FLOODING 17,964,982 23,916,682 1 18 41,881,664 TORNADO 11,777,457 6,610 0 2 11,784,068 WILDFIRE 1,512,010 5,555 1 1,517,565 S. T-STORM-WIND 5,428,724 69,797 1 5,498,521 WINTER WEATHER 420,695 482,478 0 0 903,173 LIGHTNING 121,543 0 0 121,543 COLD 77,641 77,641 HEAT 1 0 Total 130,438,013 38,292,703 3 24 168,730,716
Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses S. COASTAL FLOOD 0.8% 0.6% HURRICANE TS/D 55.1% 0.4% 1.0% 42.7% DROUGHT 3.6% 35.3% 10.8% HAIL 12.0% 0.2% 1.7% 2.7% 9.3% RIVERINE FLOODING 13.8% 62.5% 46.9% 77.6% 24.8% TORNADO 9.0% 0.0% 14.4% 10.0% 7.0% WILDFIRE 1.2% 0.0% 3.2% 0.9% S. T-STORM-WIND 4.2% 0.2% 3.0% 3.3% WINTER WEATHER 0.3% 1.3% 5.8% 0.5% 0.5% LIGHTNING 0.1% 3.4% 1.5% 0.1% COLD 0.2% 0.0% HEAT 27.8% 0.5% Total 100% 100% 100% 100% 100% 201 CHAMPS ’17: A Hazard Assessment for Texas
The map below shows the forecast losses for counties in Region 3. The inset table reports the total dollar loss forecast for the highest-loss counties and those county’s percentages of the overall regional forecast. From this table you can see that Cameron, Hidalgo and Val Verde make-up 73% of the Region 3’s forecast losses.
Map A1.3.1: Region 3 Weather-Related Dollar Loss Forecast: 2019 - 2023
202 CHAMPS ’17: A Hazard Assessment for Texas
A1.4: REGION 4 WEATHER-RELATED HAZARD SUMMARY Region 4 had 3% of the statewide property losses over the base period and 6% of the statewide crop losses. It had more Extreme Cold losses than any other region. Table A1.4.1: Region 4 Weather Related Hazard Impacts: 1996 - 2016 21-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) HURRICANE TS/D DROUGHT 41,440,402 796,987,279 2 838,427,681 HAIL 931,110,308 67,569,148 63 998,679,456 S. COASTAL FLOOD RIVERINE FLOODING 323,319,967 6,895,726 9 9 330,215,693 TORNADO 17,273,139 1,497,574 1 16 18,770,713 S. T-STORM-WIND 73,352,276 2,616,133 4 30 75,968,409 WILDFIRE 9,711,456 1,568,155 1 15 11,279,611 WINTER WEATHER 1,694,614 449,707 14 20 2,144,321 LIGHTNING 908,412 1 3 908,412 COLD 5,377,835 5,377,835 HEAT 1 Total 1,404,188,409 877,583,722 31 158 2,281,772,131 Average Annual Impacts (21-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual HURRICANE TS/D DROUGHT 1,973,352 37,951,775 0 39,925,128 HAIL 44,338,586 3,217,578 13 47,556,165 S. COASTAL FLOOD RIVERINE FLOODING 15,396,189 328,368 2 2 15,724,557 TORNADO 822,530 71,313 0 3 893,843 S. T-STORM-WIND 3,492,966 124,578 1 6 3,617,543 WILDFIRE 462,450 74,674 0 3 537,124 WINTER WEATHER 80,696 21,415 3 4 102,111 LIGHTNING 43,258 0 1 43,258 COLD 256,087 256,087 HEAT 0 Total 66,866,115 41,789,701 6 32 108,655,816 Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses HURRICANE TS/D DROUGHT 3.0% 90.8% 1.3% 36.7% HAIL 66.3% 7.7% 39.9% 43.8% S. COASTAL FLOOD RIVERINE FLOODING 23.0% 0.8% 29.0% 5.7% 14.5% TORNADO 1.2% 0.2% 3.2% 10.1% 0.8% S. T-STORM-WIND 5.2% 0.3% 12.9% 19.0% 3.3% WILDFIRE 0.7% 0.2% 3.2% 9.5% 0.5% WINTER WEATHER 0.1% 0.1% 45.2% 12.7% 0.1% LIGHTNING 0.1% 3.2% 1.9% 0.0% COLD 0.4% 0.2% HEAT 3.2% Total 100% 100% 100% 100% 100%
203 CHAMPS ’17: A Hazard Assessment for Texas
Forecasted property losses for Region 4, are expected to average $75 million a year over the forecast period. This is $8 million higher than in the base period average Table A1.4.2: Region 4 Weather Related Impact Forecast: 2019 - 2023
5-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) S. COASTAL FLOOD HURRICANE TS/D DROUGHT 11,777,673 201,070,268 1 212,847,941 HAIL 244,895,217 16,087,892 16 260,983,110 RIVERINE FLOODING 87,209,363 1,739,708 2 2 88,949,071 TORNADO 4,375,771 356,565 0 4 4,732,336 WILDFIRE 4,602,613 714,701 1 7 5,317,313 S. T-STORM-WIND 18,708,643 622,889 1 7 19,331,532 WINTER WEATHER 343,071 91,218 3 4 434,289 LIGHTNING 237,601 0 1 237,601 COLD 1,231,676 1,231,676 HEAT 0 Total 373,381,628 220,683,241 8 42 594,064,869
Average Annual Forecasted Impacts (5-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual S. COASTAL FLOOD HURRICANE TS/D DROUGHT 2,355,535 40,214,054 0 42,569,588 HAIL 48,979,043 3,217,578 3 52,196,622 RIVERINE FLOODING 17,441,873 347,942 0 0 17,789,814 TORNADO 875,154 71,313 0 1 946,467 WILDFIRE 920,523 142,940 0 1 1,063,463 S. T-STORM-WIND 3,741,729 124,578 0 1 3,866,306 WINTER WEATHER 68,614 18,244 1 1 86,858 LIGHTNING 47,520 0 0 47,520 COLD 246,335 246,335 HEAT 0 Total 74,676,326 44,136,648 2 8 118,812,974
Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses S. COASTAL FLOOD HURRICANE TS/D DROUGHT 3.2% 91.1% 1.3% 35.8% HAIL 65.6% 7.3% 37.3% 43.9% RIVERINE FLOODING 23.4% 0.8% 31.9% 5.8% 15.0% TORNADO 1.2% 0.2% 3.2% 9.7% 0.8% WILDFIRE 1.2% 0.3% 7.0% 17.0% 0.9% S. T-STORM-WIND 5.0% 0.3% 13.3% 17.1% 3.3% WINTER WEATHER 0.1% 0.0% 38.0% 10.0% 0.1% LIGHTNING 0.1% 3.1% 1.8% 0.0% COLD 0.3% 0.2% HEAT 3.6% Total 100% 100% 100% 100% 100% 204 CHAMPS ’17: A Hazard Assessment for Texas
The map below shows the forecast losses for counties in Region 4. . The inset table reports the total dollar loss forecast for the highest-loss counties and those county’s percentages of the overall regional forecast. From this table you can see that El Paso, Andrews and Midland make-up 61% of the Region 4’s forecast losses.
Map A1.4.1: Region 4 Weather-Related Dollar Loss Forecast: 2019 - 2023
205 CHAMPS ’17: A Hazard Assessment for Texas
A1.5: REGION 5 WEATHER-RELATED HAZARD SUMMARY Region 5 had 9% of the statewide property losses over the base period and 78% of the statewide crop losses. It had more Drought, Wildfire and Severe Thunderstorm wind damage than any other region. Table A1.5.1: Region 5 Weather Related Hazard Impacts: 1996 - 2016 21-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) HURRICANE TS/D DROUGHT 1,089,517,981 11,146,482,645 5 30 12,236,000,626 HAIL 2,108,185,898 571,442,441 3 33 2,679,628,339 S. COASTAL FLOOD RIVERINE FLOODING 249,271,812 444,494,372 17 12 693,766,184 TORNADO 50,189,690 88,811,174 5 74 139,000,864 S. T-STORM-WIND 650,527,235 48,660,374 11 95 699,187,609 WILDFIRE 273,911,995 185,920,455 20 108 459,832,450 WINTER WEATHER 98,824,679 5,118,347 64 442 103,943,026 LIGHTNING 6,215,910 103 5 11 6,216,013 COLD 4,688,293 596,884 2 6 5,285,177 HEAT 55,620 556,200 9 2 611,820 Total 4,531,389,113 12,492,082,995 141 813 17,023,472,108 Average Annual Impacts (21-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual HURRICANE TS/D DROUGHT 51,881,809 530,784,888 1 6 582,666,696 HAIL 100,389,805 27,211,545 1 7 127,601,349 S. COASTAL FLOOD RIVERINE FLOODING 11,870,086 21,166,399 3 2 33,036,485 TORNADO 2,389,985 4,229,104 1 15 6,619,089 S. T-STORM-WIND 30,977,487 2,317,161 2 19 33,294,648 WILDFIRE 13,043,428 8,853,355 4 22 21,896,783 WINTER WEATHER 4,705,937 243,731 13 88 4,949,668 LIGHTNING 295,996 5 1 2 296,001 COLD 223,252 28,423 0 1 251,675 HEAT 2,649 26,486 2 0 29,134 Total 215,780,434 594,861,095 28 163 810,641,529 Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses HURRICANE TS/D DROUGHT 24.0% 89.2% 3.5% 3.7% 71.9% HAIL 46.5% 4.6% 2.1% 4.1% 15.7% S. COASTAL FLOOD RIVERINE FLOODING 5.5% 3.6% 12.1% 1.5% 4.1% TORNADO 1.1% 0.7% 3.5% 9.1% 0.8% S. T-STORM-WIND 14.4% 0.4% 7.8% 11.7% 4.1% WILDFIRE 6.0% 1.5% 14.2% 13.3% 2.7% WINTER WEATHER 2.2% 0.0% 45.4% 54.4% 0.6% LIGHTNING 0.1% 0.0% 3.5% 1.4% 0.0% COLD 0.1% 0.0% 1.4% 0.7% 0.0% HEAT 0.0% 0.0% 6.4% 0.2% 0.0% Total 100% 100% 100% 100% 100% 206 CHAMPS ’17: A Hazard Assessment for Texas
Forecasted property losses for Region 5, are expected to average $239 million a year over the forecast period. This is $22 million higher than in the base period average Table A1.5.2: Region 5 Weather Related Impact Forecast: 2019 - 2023
5-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) S. COASTAL FLOOD HURRICANE TS/D DROUGHT 290,341,921 2,812,122,987 1 8 3,102,464,908 HAIL 518,817,233 136,057,724 1 8 654,874,957 RIVERINE FLOODING 64,108,044 112,140,563 4 3 176,248,607 TORNADO 11,953,924 21,145,518 1 18 33,099,442 WILDFIRE 124,027,752 84,734,928 9 50 208,762,680 S. T-STORM-WIND 162,451,173 11,585,803 3 23 174,036,977 WINTER WEATHER 20,256,552 1,038,197 13 92 21,294,749 LIGHTNING 1,519,222 25 1 3 1,519,247 COLD 987,576 126,499 0 1 1,114,075 HEAT 16,548 155,212 3 1 171,761 Total 1,194,479,946 3,179,107,457 37 206 4,373,587,403
Average Annual Forecasted Impacts (5-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual S. COASTAL FLOOD HURRICANE TS/D DROUGHT 58,068,384 562,424,597 0 2 620,492,982 HAIL 103,763,447 27,211,545 0 2 130,974,991 RIVERINE FLOODING 12,821,609 22,428,113 1 1 35,249,721 TORNADO 2,390,785 4,229,104 0 4 6,619,888 WILDFIRE 24,805,550 16,946,986 2 10 41,752,536 S. T-STORM-WIND 32,490,235 2,317,161 1 5 34,807,395 WINTER WEATHER 4,051,310 207,639 3 18 4,258,950 LIGHTNING 303,844 5 0 1 303,849 COLD 197,515 25,300 0 0 222,815 HEAT 3,310 31,042 1 0 34,352 Total 238,895,989 635,821,491 7 41 874,717,481
Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses S. COASTAL FLOOD HURRICANE TS/D DROUGHT 24.3% 88.5% 3.3% 3.8% 70.9% HAIL 43.4% 4.3% 1.9% 3.9% 15.0% RIVERINE FLOODING 5.4% 3.5% 11.8% 1.5% 4.0% TORNADO 1.0% 0.7% 3.2% 8.6% 0.8% WILDFIRE 10.4% 2.7% 25.3% 24.2% 4.8% S. T-STORM-WIND 13.6% 0.4% 7.3% 11.1% 4.0% WINTER WEATHER 1.7% 0.0% 35.8% 44.7% 0.5% LIGHTNING 0.1% 0.0% 3.4% 1.3% 0.0% COLD 0.1% 0.0% 1.2% 0.7% 0.0% HEAT 0.0% 0.0% 6.9% 0.3% 0.0% Total 100% 100% 100% 100% 100%
207 CHAMPS ’17: A Hazard Assessment for Texas
The map below shows the forecast losses for counties in Region 5. . The inset table reports the total dollar loss forecast for the highest-loss counties and those county’s percentages of the overall regional forecast. From this table you can see that Lubbock, Montague and Parmer make-up 49% of the Region 5’s forecast losses.
Map A1.5.1: Region 5 Weather-Related Dollar Loss Forecast: 2019 - 2023
208 CHAMPS ’17: A Hazard Assessment for Texas
A1.6: REGION 6 WEATHER-RELATED HAZARD SUMMARY Region 6 had 10% of the statewide property losses over the base period and 2% of the statewide crop losses. It had more Riverine Flooding losses than any other region. Table A1.6.1: Region 6 Weather Related Hazard Impacts: 1996 - 2016 21-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) HURRICANE TS/D 5,302,718 3,904,892 1 2 9,207,610 DROUGHT 130,396,702 286,270,584 416,667,286 HAIL 2,285,536,463 48,807,081 20 2,334,343,544 S. COASTAL FLOOD 1,313,713 1,313,713 RIVERINE FLOODING 1,584,251,693 22,888,461 169 6,550 1,607,140,154 TORNADO 252,805,237 941,914 33 143 253,747,151 S. T-STORM-WIND 180,726,508 2,970,368 1 83 183,696,876 WILDFIRE 301,163,598 75,181 4 9 301,238,779 WINTER WEATHER 7,399,423 153,064 14 35 7,552,487 LIGHTNING 6,140,647 10 49 6,140,647 COLD 1 HEAT 28 Total 4,755,036,702 366,011,545 261 6,891 5,121,048,247 Average Annual Impacts (21-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual HURRICANE TS/D 252,510 185,947 0 0 438,458 DROUGHT 6,209,367 13,631,933 19,841,299 HAIL 108,835,070 2,324,147 4 111,159,216 S. COASTAL FLOOD 62,558 62,558 RIVERINE FLOODING 75,440,557 1,089,927 34 1,310 76,530,484 TORNADO 12,038,345 44,853 7 29 12,083,198 S. T-STORM-WIND 8,606,024 141,446 0 17 8,747,470 WILDFIRE 14,341,124 3,580 1 2 14,344,704 WINTER WEATHER 352,353 7,289 3 7 359,642 LIGHTNING 292,412 2 10 292,412 COLD 0 HEAT 6 Total 226,430,319 17,429,121 52 1,378 243,859,440 Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses HURRICANE TS/D 0.1% 1.1% 0.4% 0.0% 0.2% DROUGHT 2.7% 78.2% 8.1% HAIL 48.1% 13.3% 0.3% 45.6% S. COASTAL FLOOD 0.0% 0.0% RIVERINE FLOODING 33.3% 6.3% 64.8% 95.1% 31.4% TORNADO 5.3% 0.3% 12.6% 2.1% 5.0% S. T-STORM-WIND 3.8% 0.8% 0.4% 1.2% 3.6% WILDFIRE 6.3% 0.0% 1.5% 0.1% 5.9% WINTER WEATHER 0.2% 0.0% 5.4% 0.5% 0.1% LIGHTNING 0.1% 3.8% 0.7% 0.1% COLD 0.4% HEAT 10.7% Total 100% 100% 100% 100% 100% 209 CHAMPS ’17: A Hazard Assessment for Texas
Forecasted property losses for Region 6, are expected to average $272 million a year over the forecast period. This is $46 million higher than in the base period average Table A1.6.2: Region 6 Weather Related Impact Forecast: 2019 - 2023
5-Year Totals Property Losses Crop Losses Total Losses (2016 dollars) (2016 dollars) Deaths Injuries (2016 dollars) S. COASTAL FLOOD 654,904 654,904 HURRICANE TS/D 1,620,788 1,137,612 0 1 2,758,399 DROUGHT 33,907,471 72,222,612 106,130,083 HAIL 600,627,607 11,620,734 5 612,248,340 RIVERINE FLOODING 451,918,890 5,774,482 47 1,806 457,693,372 TORNADO 68,217,871 224,265 9 37 68,442,136 WILDFIRE 152,497,368 34,264 2 4 152,531,632 S. T-STORM-WIND 47,145,796 707,230 0 21 47,853,026 WINTER WEATHER 1,584,328 31,047 3 7 1,615,376 LIGHTNING 1,589,215 3 13 1,589,215 COLD 0 HEAT 9 Total 1,359,764,238 91,752,247 73 1,894 1,451,516,485
Average Annual Forecasted Impacts (5-years) Property Losses Crop Losses (2016 dollars) (2016 dollars) Deaths Injuries Total Annual S. COASTAL FLOOD 130,981 130,981 HURRICANE TS/D 324,158 227,522 0 0 551,680 DROUGHT 6,781,494 14,444,522 21,226,017 HAIL 120,125,521 2,324,147 1 122,449,668 RIVERINE FLOODING 90,383,778 1,154,896 9 361 91,538,674 TORNADO 13,643,574 44,853 2 7 13,688,427 WILDFIRE 30,499,474 6,853 0 1 30,506,326 S. T-STORM-WIND 9,429,159 141,446 0 4 9,570,605 WINTER WEATHER 316,866 6,209 1 1 323,075 LIGHTNING 317,843 1 3 317,843 COLD 0 HEAT 2 Total 271,952,848 18,350,449 15 379 290,303,297
Percentages % of Prop. % of Crop % of % of Losses Losses Deaths Injuries % of Total Losses S. COASTAL FLOOD 0.0% 0.0% HURRICANE TS/D 0.1% 1.2% 0.4% 0.0% 0.2% DROUGHT 2.5% 78.7% 7.3% HAIL 44.2% 12.7% 0.3% 42.2% RIVERINE FLOODING 33.2% 6.3% 64.3% 95.3% 31.5% TORNADO 5.0% 0.2% 12.3% 2.0% 4.7% WILDFIRE 11.2% 0.0% 2.8% 0.2% 10.5% S. T-STORM-WIND 3.5% 0.8% 0.3% 1.1% 3.3% WINTER WEATHER 0.1% 0.0% 4.1% 0.4% 0.1% LIGHTNING 0.1% 3.5% 0.7% 0.1% COLD 0.3% HEAT 12.0% Total 100% 100% 100% 100% 100%
210 CHAMPS ’17: A Hazard Assessment for Texas
The map below shows the forecast losses for counties in Region 6. The inset table reports the total dollar loss forecast for the highest-loss counties and those county’s percentages of the overall regional forecast. From this table you can see that Bexar, Travis and Bastrop make-up 51% of the Region 6’s forecast losses.
Map A1.6.1: Region 6 Weather-Related Dollar Loss Forecast: 2019 - 2023
211 CHAMPS ’17: A Hazard Assessment for Texas
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212 CHAMPS ’17: A Hazard Assessment for Texas
Appendix 2: Weather-Related Hazard Data and Processing
The material below describes the weather-related hazard data used in the report: where it came from, how it was prepared and the methodology used to forecast future impacts. Also below is a presentation of the weather pattern-related hazard change rates used in the forecast and an explanation of those rates, provided by Dr. John Nielsen Gammon, the Texas State Climatologist (and a member of the State Hazard Mitigation Team.
A2.1: WEATHER-RELATED HAZARD DATA This Assessment relies heavily of the content of the NOAA NCEI Storm Events Database. Below, background information on the NCEI data is discussed. This is followed by a presentation of how that data was processed to determine the base period amounts used in this report. Following this section is the presentation in section A7.3 of the whether-related hazard impact forecast model. About the NCEI data The NCEI Storm Events Database is a rich centralized repository of weather-related hazard events nationwide. Among other things, it is the source used by NOAA to populate its monthly storm data publication. The following are Quotes from the NOAAS NCEI website (bolding added): From https://www.ncdc.noaa.gov/about: “NCEI is responsible for hosting and providing access to one of the most significant archives on Earth, with comprehensive oceanic, atmospheric, and geophysical data. From the depths of the ocean to the surface of the sun and from million-year-old ice core records to near real-time satellite images, NCEI is the Nation’s leading authority for environmental information.” From https://www.ncdc.noaa.gov/stormevents/ “NCEI helps describe the climate of the United States and it acts as the "Nation's Scorekeeper" regarding the trends and anomalies of weather and climate. NCEI's climate data have been used in a variety of applications including agriculture, air quality, construction, education, energy, engineering, forestry, health, insurance, landscape design, livestock management, manufacturing, national security, recreation and tourism, retailing, transportation, and water resources management.” “The Storm Events Database contains the records used to create the official NOAA Storm Data publication…
213 CHAMPS ’17: A Hazard Assessment for Texas
The NCEI storm events database is comprehensive in that it covers all of the weather-related hazards that effect Texas. The comprehensiveness of this data allows study the impacts of individual hazards year after year, but also to compare the impacts of different hazard, one to another, which provides a framework for understanding relative risks. There are 85,571 records in the Storm Events Database that describe weather- related hazards that occurred in Texas over the period of January 1, 1996 through December 31, 2016. Of these, 23,278 include associated impacts (property losses, crop losses, deaths or injuries). The sources for this data are for the most part local (locally sourced information is frequently the best). Here is a list of the identified sources for the 23,278 records used in the analysis. NCEI Data sorces 911 Call Center COOP Observer LAW ENFORCEMENT Park/Forest Service AIRPLANE PILOT COOP STATION Local Official POST OFFICE AMATEUR RADIO County Official Mariner Public ARPT EQUIP(AWOS,ASOS) Department of Highways Mesonet RAWS ASOS DEPT OF HIGHWAYS METEOROLOGIST(NON NWS) River/Stream Gage AWOS Drought Monitor NEWSPAPER SHAVE Project AWOS,ASOS,MESONET,ETC EMERGENCY MANAGER NWS Employee Social Media Broadcast Media Fire Department/Rescue NWS EMPLOYEE(OFF DUTY) State Official C-MAN Station FIRE DEPT/RESCUE SQUAD NWS STORM SURVEY STORM CHASER Coast Guard GENERAL PUBLIC OFFICIAL NWS OBS. TRAINED SPOTTER COASTAL OBSERVING STATION GOVT OFFICIAL Official NWS Observations UNKNOWN CoCoRaHS INSURANCE COMPANY OTHER FEDERAL AGENCY UTILITY COMPANY The event descriptions in the Storm Events Database (some of which are included in the body of this assessment) are chilling accounts of hazard causes and effects. An extract of the NCEI FAQ that describes the accuracy of the Storm Event Database is provided below (bolding added). It explains that the NWS does not guarantee the accuracy of all of the data, however they also say the effort was made to use the “best available information”. From https://www.ncdc.noaa.gov/stormevents/faq.jsp Storm Data is an official publication of the National Oceanic and Atmospheric Administration (NOAA) which documents the occurrence of storms and other significant weather phenomena having sufficient intensity to cause loss of life, injuries, significant property damage, and/or disruption to commerce. In addition, it is a partial record of other significant meteorological events, such as record maximum or minimum temperatures or precipitation that occurs in connection with another event. Some information appearing in Storm Data may be provided by or gathered from sources outside the National Weather Service (NWS),
214 CHAMPS ’17: A Hazard Assessment for Texas
such as the media, law enforcement and/or other government agencies, private companies, individuals, etc. An effort is made to use the best available information but because of time and resource constraints, information from these sources may be unverified by the NWS. Therefore, when using information from Storm Data, customers should be cautious as the NWS does not guarantee the accuracy or validity of the information. The NCEI data was used in this analysis because it provides a comprehensive picture across all hazards across all of Texas. This information provides a level of information appropriate to understanding hazard risk. It is not intended to be sufficient for engineering or for litigation or for other highly specific determinations. To prioritize mitigation strategies it was deemed sufficient to understand the general and comparative magnitudes of the various hazard impacts. This is the best data available to do that on a statewide level in Texas NCEI Data Processing: The NCEI data was downloaded for Texas included 85,571 different records. One of the first things done with this was to pare down that list to the number of records that represented actual dollar losses: 23,278. These records arrived with Federal Information Processing Standard (FIPS) codes that related county names with county IDs – used to link that data to maps. Processing was performed to link appropriate sets of FIPS county codes to the DPS regions used in the analysis. In this process it was determined that several counties had incorrect FIPS codes in the original data. These were fixed. Next, the hazard type categories used in the NCEI were grouped into categories used in this report according to the following table.
Champs '17 Categories NCEI Categories Flood Flood Heavy Rain Flash Flood Seiche Coastal Flood Storm Surge/Tsunami Storm Surge/Tide Hurricane (TS/D) Hurricane (Typhoon) Tropical Storm Hurricane Tropical Depression Wildfire Wildfire Tornado Tornado Waterspout Drought Drought Dust Storm Extreme Heat Excessive Heat Heat Extreme Cold Extreme Cold/Wind Chill Cold/Wind Chill Hailstorm Hail Severe Winter Weather Sleet Frost/Freeze Ice Storm Winter Weather Winter Storm Heavy Snow Blizzard Severe Winds High Wind Strong Wind Thunderstorm Wind THUNDERSTORM WINDS Lightning Lightning 215 CHAMPS ’17: A Hazard Assessment for Texas
Then, property and crop loss values in the database were corrected for inflation to produce dollar estimates in 2016 dollars. This was done according to the following example (example for 1996 data):
The results of these processes were then added by CHAMPS ’17 Hazard Categories to determine various levels of summaries: County, Region and State and divided by the relevant data collection periods in years to determine average annual impacts for those levels of geography. Next, maps and tables were produced that went into the report.
216 CHAMPS ’17: A Hazard Assessment for Texas
A2.2: WEATHER-RELATED HAZARD FORECAST METHODOLOGY
To forecast future hazard impacts, average annual county property loss, deaths and injuries for each of the twelve hazards were multiplied:
1. Times the previous annual population growth rates of those counties (to account for population and building development/exposure growth); and
2. Times annualized weather change multipliers that represent expected changes to the destructive capacity of each of the different hazards (to account for weather pattern changes).
The annualized rates of population change experienced by each county over the period of 2010 to 2016 are used to accommodate expected population and land use changes annually, moving forward. The reason these are used is to represent population and land development changes. As population increases so does development and expected non-crop related hazard impacts.
Crop Impacts are not multiplied times the population growth factors because population growth does not imply farmland growth. Annualized Crop Dollar Losses by county are multiplied only times number 2 above (the annualized weather change multipliers).
The forecast was summed from annual projections to cover the 5-year period of January 1, 2019 through December 31, 2023. Forecast dollar losses per county are reported on the Statewide Dollar Loss Forecast maps for each hazard and for all Hazards together in section 3.0. All forecast impacts per county are also summed by region to produce the regional impact forecasts tables used in the report and in Appendix 1.
The figures on the following pages present the model used to forecast future risk. The first figure shows the calculations used in the actual forecast. The second figure shows the methodology used to prepare the Risk Change Factors The annualized Weather-Related Change rates are discussed in section A2.3 below.
217 CHAMPS ’17: A Hazard Assessment for Texas
PL, CL, D, & I *
Co. name, FIPS, Reg. # Co.FIPS, name,
All Hazards and each hazard: 13 each hazard: and Hazards All
All hazards for each region St. hazards & All
Each hazard: region totals region Eachhazard:
(12 * 4 * 254 = 12,129 fields) = 12,129 * 254 * 4 (12
4 fields for each hazard in each co. for in fields 4 each hazard
5-Year Forecast total impacts total Forecast 5-Year
Basicinfo: County fields 3
1 Staterow 1
254 county records records county 254
Statewide maps Statewide
Table Sums:Table
Columns / Fields Columns
Rows/ Records
Co. W-H Forecast: 2019-23: 5-yearsCo. 2019-23: Forecast: W-H
Maps
(Output)
(Output)
Sum
=
X
=
X
=
X
=
X
=
X
=
Risk Change Risk Factors
Risk Change Risk Factors
Risk Change Risk Factors
Risk Change Risk Factors
Risk Change Risk Factors
Risk Change Risk Factors
Co.Impact '18 forecast
Co.Impact '19 forecast
Co.Impact '20 forecast
Co.Impact '21 forecast
Co.Impact '22 forecast
Co.Impact '23 forecast
X
(12 * 4 * 254 = 12,129) * 254 * 4 (12
PL, CL, D, & I *
Co. name, FIPS, Reg. # Co.FIPS, name,
4 fields for fields 4 each hazard.
Forecasted '17 Co. '17 Forecasted Impacts
Basicinfo: County fields 3
1 Staterow 1
254 county records records county 254
Columns / Fields Columns
Rows/ Records
Co. Weather-Hazard Forecast: '17 Co.Forecast: Weather-Hazard
=
CL - Crop Losses
Multiplied times: Multiplied
(12)
I - Injuries
D - Deaths and - Deaths D
PL - Property Losses,
Multiplied times: Multiplied
(12 * 254 = 3048) * 254 (12
Co. name, FIPS, Reg. # Co.FIPS, name,
Ann.Change Hazard Rates
Ann. P&H Change Rates
Basicinfo: County fields 3
1 Staterow 1
254 county records records county 254
Columns / Fields Columns
Rows/ Records
Risk Change Risk Factors
X
I I = Injuries (direct & indirect)
D = Deaths (direct & indirect)
-
-
+
=
+
=
=
+
+
=
+
+
1.12173
0.91912
1.00000
0.89035
1.05523
1.00000
1.00000
1.04281
1.11298
1.00000
1.04281
1.15717
=
X
CL CL = Crop Losses
PL PL = Property Losses
Drought
Flooding
Ext.Cold
Lightning
Ext.Heat
Tornados
Wildfire**
Hailstorms
Hurricane TS/D Hurricane
Winter Weather Winter
* Key
(12 * 4 * 254 = 12,129 fields) = 12,129 * 254 * 4 (12
PL, CL, D, & I *
AverageAnn Impacts for 2016
(Extrap. from annual rates)
--(**) years or 6 10.5years
(12 * 4 * 254 = 12,129 fields) = 12,129 * 254 * 4 (12
PL, CL, D, & I *
(12 * 4 * 254 = 12,129 fields) = 12,129 * 254 * 4 (12
PL, CL, D, & I *
Co. name, FIPS, Reg. # Co.FIPS, name,
Sev.T-storm Winds
KEY KEY FORMULA
Severe CoastalSevere Flood**
Weather Change Weather Average Update
AverageImpacts Annual (2006/11) Hist.
Tot. hist. losses by hazard (21yrs/12yrs**) Tot.hazard losses by hist.
Basicinfo: County fields 3
1 State-total 1 (sum) record
254 county records records county 254
Columns / Fields Columns
Rows/ Records CountyHistory Hazard Weather-Related Table A2.2.1: Texas Weather-Related Hazard Risk Forecast Model Risk Forecast Hazard Weather-Related Texas A2.2.1: Table
218 CHAMPS ’17: A Hazard Assessment for Texas
: 12 per Co. per :12
=
X
Co. name, FIPS, Reg. # Co.FIPS, name,
Ann.P&H Change (3048) Rates
Ann.Change Hazard (12) Rates
Ann.pop. change (254) rates
Product of: Product
ChangeMultipliers
Basicinfo: County fields 3
1 Staterow 1
254 county records records county 254
KEY KEY FORMULA
Columns / Fields Columns
Rows/ Records
Risk Change Risk Factors
-
-
+
=
+
=
=
+
+
=
+
+
1.011
0.992
1.000
0.989
1.009
1.000
1.000
1.004
1.018
1.000
1.004
1.014
Wildfire
Drought
Flooding
Ext.Cold
Lightning
Ext.Heat
Tornados
Hailstorms
Hurricane TS/D Hurricane
Winter Weather Winter
1 - Hazard change multipliers change - 1 Hazard
Sev.T-storm Winds
Severe CoastalSevere Flood
Ann. Change Hazard (12) Rates
Columns / Fields Columns
Rows/ Records
Hazard Context: Weather Change Context: Weather Hazard
2010, 2016 and 2024 and 2016 2010,
(used to avoid compounding error) to avoidcompounding (used
=10^(LOG10(2016pop/2010pop)/6)
population change calculatedas: change population
Annualized rateof county Annualized
Ann. Co. pop. change (254) rates
2010-16 calculated change rate calculated change 2010-16
2016 - Pop Est. (TX St,. Data St,. - Center) Est. Pop 2016 (TX
2010 - Pop (2010 US Census) - (2010 Pop 2010
Co. name, FIPS, area (sq. ml), Reg. # ml), area (sq. Co.FIPS, name,
Regional populations for populations Regional
Forecasted Populations for 2024 ForecastedJan.Populations 1,
Population Info fields) Population (4
Basicinfo: County fields 4
1 State row (part sum, part calculation) part sum, Staterow 1 (part
254 county records records county 254
Regionalsummary showing: tables
Columns / Fields Columns
Rows/ Records
CountyContext: PopulationChange Table A2.2.2: Weather Hazard Risk Change Factors Risk Change Hazard Weather A2.2.2: Table (Output)
219 CHAMPS ’17: A Hazard Assessment for Texas
A2.3: WEATHER PATTERN RELATED HAZARD CHANGE RATES
The annualized Weather-Related Change rates used to project expected weather pattern damage changes were provided to this study by Dr. John Nielsen-Gammon, the Texas State Climatologist. The following is his bio:
About Dr. Nielsen-Gammon
John Nielsen-Gammon is the Texas State Climatologist and a Regents Professor of Atmospheric Sciences at Texas A&M University. He oversees the Office of the State Climatologist (OSC) at Texas A&M. OSC activities include climate data analysis and research, state government service, outreach presentations, press interviews, and federal-state climate information coordination. The OSC receives base funding from Texas A&M University and special project funding from state agencies and other sources. Recent sponsored research includes a feasibility study on a weather network for the Texas Water Development Board and a review of extreme precipitation risk analysis for the Texas Commission on Environmental Quality.
Dr. Nielsen-Gammon is a member of the Texas Drought Preparedness Council and the State Hazard Mitigation Team. He hosts a weekly Webex webinar with joint federal-state participation in which we collect and distribute drought information and refine recommendations for the proper depiction of drought severity in Texas. The OSC also produces and posts detailed drought monitoring maps for the state of Texas and coordinates with federal agencies on the provision of climate services to the state of Texas.
The weather pattern related hazard change factors used are in the table below. Dr. Nielsen –Gammon’s explanation of these factors is included on the pages that follow. Hazard Type Change Rate Impact Vector Hurricane TS/D 1.014 + Drought 1.004 + Hailstorms 1.000 = Severe Coastal Flood 1.018 + Flooding 1.004 + Tornados 1.000 = Sev. T-storm Winds 1.000 = Wildfire 1.009 + Winter Weather 0.989 - Lightning 1.000 = Ext. Cold 0.992 - Ext. Heat 1.011 + 220 CHAMPS ’17: A Hazard Assessment for Texas
Climate change impact on extreme weather hazards in Texas
John Nielsen-Gammon, Sept. 12, 2017
Estimation of a changing climate's impact on damage produced by extreme weather requires information regarding (1) the expected trend in the frequency or magnitude of extreme weather and (2) the relationship between changes in extreme weather and changes in damage.
Most projections of extreme weather are based on a comparison of extreme weather during two widely-separated time periods. These projections are converted into an annual multiplier by assuming that the annual multiplier is constant during the interval. In order to obtain an annual multiplier, the relationship between changes in extreme weather and changes in damages is estimated.
The expected trend in the frequency or magnitude of extreme weather is estimated using projections using the RCP 8.5 pathway (van Vuuren et al. 2011) whenever possible. This pathway assumes a continuing increase in greenhouse gases throughout the 21st century. This is convenient for numerically estimating the near-term trend because this projection most closely approximates a constant annual multiplier. Other pathways project a leveling off of the rate of climate change, making it more difficult to infer short-term changes from any published long-term changes. All projection pathways are similar during the first third of the 21st century, so all projected short-term changes are insensitive to the projected pathway.
The relationship between changes in extreme weather and changes in damages is estimated using Hsiang et al. (2017), who used a proprietary insurance industry risk model to estimate wind and storm surge damages associated with landfalling hurricanes. We interpret Fig. S10 of Hsiang et al. (2017) to imply approximately a factor of 5 increase in hurricane damages between the historical period and the late 21st century under the RCP 8.5 scenario, which corresponds to a global temperature change of about 4.5 °C (Collins et al. 2013). We assume that damage is proportional to changes in the power dissipation index of hurricanes, and use the projected 40% increase of power dissipation index estimate by Knutson et al. (2013) for the RCP 4.5 scenario, which involves a 2 °C change over the same interval (Collins et al. 2013). With
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less than half of the RCP 8.5 temperature change, the fractional damage should be the less than the square root of the RCP 8.5 fractional damage, or about a factor of two. Since a 40% increase in the relevant measure of damaging hurricane strength leads to a 100% increase in damages, the damage multiplier is 2.5.
Specific values for the annual multiplier for climate change impact on damages from particular classes of extreme events are described separately below.
For hurricanes, tropical storms, and tropical depressions, we directly use the Hsiang et al. (2017) factor of 5 increase in projected damages from the 20th century to the last two decades of the 21st century in Texas to infer a corresponding annual damage change factor of 1.014, or an increase of 1.4% per year in expected damages from hurricanes. Severe coastal floods are affected both by changes in hurricane intensity and changes in sea level. We assume that sea level rise will contribute slightly more than 1/3 of the overall storm surge damage increase, with hurricane intensity responsible for the remainder. This leads to an annual damage change factor of 1.018, or an increase of 1.8% per year in expected damages from severe coastal flooding.
For drought, we use the projected 4 °C change between the recent past and the end of the 21st century under RCP 8.5 (Collins et al. 2013) and apply the Clausius-Clapeyron relation under the assumption of constant relative humidity to infer an approximately 30% change in summertime evaporation potential by the end of the 21st century. Projected changes in rainfall for Texas are small and inconsistent among models (Collins et al. 2013), so we expect changes in drought intensity and severity to be dominated by changes in evaporation. The resulting inferred drought change is somewhat smaller than what has been inferred for the central Plains (Cook et al. 2015). With the damage multiplier, this corresponds to an annual damage change factor of 1.004, or an increase of 0.4% per year in expected damages from drought.
For extreme rainfall, the observed trends in the southern United States (Janssen et al. 2015) are consistent with the Clausius-Clapeyron relation. We assume that extreme rainfall translates directly into extreme flooding, although the observed lack of a clear trend in flooding (IPCC 2012) implies a role for reduced soil moisture in at least partially mitigating against extreme rainfall. With the
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damage multiplier, the annual damage factor is the same as for drought, 1.004, or an increase of 0.4% per year in expected damages from flooding.
For wildfire, we consider only the potential changes in very dry periods, as inferred from values of the Keetch-Byram drought index (KBDI) exceeding 750. Weatherly and Rosenbaum (2017) project a factor of three increase in such days within the southern Great Plains. We assume this translates directly to a factor of three increase in acreage burned by wildfires over the next century under the RCP 8.5 scenario. With the damage multiplier, the annual damage factor is 1.009, or an increase of 0.9% per year in expected damages from wildfire.
For heat, we assume that heat mortality is related to changes in wet bulb globe temperature, a measure used by the U.S. military for regulating strenuous outdoor activity. Projections of changes in wet bulb globe temperature are smaller than projections of changes in temperature itself, due to corresponding decreases in relative humidity. Historical trends in summertime wet bulb globe temperature in Texas are 1.0 to 2.0 °C (Knutson and Ploshay 2016) and the projected trend change relative to 1950-1999 by the end of the 21st century is 2.5 °C (Weatherly and Rosenbaum 2017), implying a 2.0°C future increase. We assume that historical summertime temperature variations relate to heat mortality in the same way as future wet bulb globe temperature changes, and use Gasparrini et al. (2015) to estimate a factor of three increase in excess mortality in major cities in Texas for every 2 °C increase in temperature. Thus the annual damage factor is 1.011, or an increase of 1.1% per year in expected mortality from heat. We do not include a damage multiplier since the damages (mortality) are estimated directly.
For extreme cold, we use Gasparrini et al. (2015) to infer a factor of three decrease in excess mortality below 0 °F for every 2 °C increase in temperature. The annual damage factor is 0.989, or a decrease of 1.1% per year in expected mortality from cold.
In the absence of specific projections on changes in winter storms, we assume that the frequency of hazardous winter weather changes in proportion with the number of days below 0 °C. For the central Great Plains, the projected number of days with maximum temperatures below 0 °C is projected to decrease by 60%, and the projected number of days with minimum temperatures below 0 °C
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is projected to decrease by 40% (Schoof and Robeson 2016). Using a nominal 50% decrease over the 90-year projection interval and applying the damage multiplier, we obtain an annual damage factor of 0.992, or a decrease of 0.8% per year in expected damages from winter storms.
Projections of changes in hail, tornadoes, severe thunderstorm winds, and lightning are still very tentative and indirect, and even the sign of the changes are not known (IPCC 2012). We therefore assume an annual damage factor of 1.0, representing no change in expected frequency of hail, tornadoes, severe thunderstorm winds, or lightning.
Citations:
Collins, M., R. Knutti, J. Arblaster, J.-L. Dufresne, T. Fichefet, P. Friedlingstein, X. Gao, W.J. Gutowski, T. Johns, G. Krinner, M. Shongwe, C. Tebaldi, A.J. Weaver and M. Wehner, 2013: Long-term Climate Change: Projections, Commitments and Irreversibility. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Cook, B. I., T.R. Ault, and J.E. Smerdon, 2015: Unprecedented 21st century drought risk in the American Southwest and Central Plains. Science Advances, doi:10.1126/sciadv.1400082.
Gasparrini, A., Y. Guo, M. Hashizume, E. Lavigne, A. Zanobetti, J. Schwartz, A. Tobias, S. Tong, J. Rocklov, B. Forsberg, M. Leone, M. De Sario, M.L. Bell, Y.- L.L. Guo, C. Wu, H. Kan, S.-M. Yi, M.d.S.Z. Stagliorio C., P.H. Nascimento S., Y. Honda, H. Kim, and B. Armstrong, 2015: Mortality risk attributable to high and low ambient temperature: a multicountry observational study. Lancet, doi:10.1016/S0140-6736(14)62114-0.
Hsiang, S., R. Kopp, A. Jina, J. Rising, M. Delgado, S. Mohan, D.J. Rasmussen, R. Muir-Wood, P. Wilson, M. Oppenheimer, K. Larsen and T. Houser, 2017: Estimating economic damage from climate change in the United States. Science, 356, 1362-1369.
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IPCC, 2012: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, UK, and New York, NY, USA, 582 pp.
Janssen, E., D.J. Wuebbles, K.E. Kunkel, S.C. Olsen, and A. Goodman, 2014: Observational- and model-based trends and projections of extreme precipitation over the contiguous United States. Earth's Future, 2, 99-113, doi:10.1002/2013ef000185.
Knutson, T.R., and J.J. Ploshay, 2016: Detection of anthropogenic influence on a summertime heat stress index. Climatic Change, doi:10.1007/s10584-016- 1708-z.
Knutson, T.R., J.J. Sirutis, G.A. Vecchi, S. Garner, M. Zhao, H.-S. Kim, M. Bender, R.E. Tuleya, I.M. Held, and G. Villarini, 2013: Dynamical downscaling projections of twenty-first-century Atlantic hurricane activity: CMIP3 and CMIP5 model-based scenarios. J. Climate, 26, 6591:6617, doi:10.1175/JCLI-D-12- 00539.1. van Vuuren, D.P., J. Edmonds, M. Kainuma, K. Riahi, A. Thomson, K. Hibbard, G.C. Hurtt, T. Kram, V. Krey, J.-F. Lamarque, T. Masui, M. Meinshausen, N. Nakicenovic, S.J. Smith, and S.K. Rose, 2011: The representative concentration pathways: an overview. Climatic Change, 109, 5-31, doi:10.1007/s10584-011- 0148-z
Weatherly, J.W., and M.A. Rosenbaum, 2017: Future projections of heat and fire-risk indices for the contiguous United States. J. Appl. Meteorol. Climatol., 56, 863-876, doi:10.1175/JAMC-D-16-0068.1.
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