Hurricane Katrina was the eleventh named storm and fifth hurricane of the 2005 Atlantic hurricane season. It was the costliest natural disaster, as well as one of the five deadliest hurricanes, in the history of the United States. The storm is currently ranked as the third most intense United States landfalling tropical cyclone, behind only the 1935 Labor Day hurricane and Hurricane Camille in 1969. Overall, at least 1,245 people died in the hurricane and subsequent floods, making it the deadliest United States hurricane since the 1928 Okeechobee hurricane. Total property damage was estimated at $108 billion (2005 USD), roughly four times the damage wrought by Hurricane Andrew in 1992.
Katrina originated over the Bahamas on August 23 from the interaction between a tropical wave and the remnants of Tropical Depression Ten. Early the following day, the new depression intensified into Tropical Storm Katrina. The cyclone headed generally westward toward Florida and strengthened into a hurricane only two hours before making landfall Hallandale Beach and Aventura on August 25. After very briefly weakening to a tropical storm, Katrina emerged into the Gulf of Mexico on August 26 and began to rapidly deepen. The storm strengthened to a Category 5 hurricane over the warm waters of the Gulf of Mexico, but weakened before making its second landfall as a Category 3 hurricane on August 29 in southeast Louisiana.
Katrina caused severe destruction along the Gulf coast from central Florida to Texas, much of it due to the storm surge and levee failure. Severe property damage occurred in coastal areas, such as Mississippi beachfront towns; over 90 percent of these were flooded. Boats and casino barges rammed buildings, pushing cars and houses inland; water reached from the beach.
Over fifty breaches in New Orleans's hurricane surge protection are the cause of the majority of the death and destruction during Katrina on August 29, 2005. Eventually 80% of the city and large tracts of neighboring parishes became flooded, and the floodwaters lingered for weeks.〔http://www.datacenterresearch.org/data-resources/katrina/facts-for-impact/〕 At least 1,400 died directly due to levee failure. All of the major studies concluded that the U.S. Army Corps of Engineers (USACE), the designers and builders of the levee system as mandated by the Flood Control Act of 1965 is responsible. This is mainly due to a decision to use shorter steel sheet pilings in an effort to save money. In January 2008, Judge Stanwood Duval, U.S. District Court, ruled that despite the corps role in the flooding, the agency could not be held financially liable because of sovereign immunity in the Flood Control Act of 1928. Exactly ten years after Katrina, J. David Rogers, lead author of a new report in the official journal of the World Water Council concluded that the flooding during Katrina “could have been prevented had the corps retained an external review board to double-check its flood-wall designs.”〔http://news.mst.edu/2015/08/flood-damage-after-katrina-could-have-been-prevented-st-expert-says/〕
There was also an investigation of the responses from federal, state and local governments, resulting in the resignation of Federal Emergency Management Agency (FEMA) director Michael D. Brown, and of New Orleans Police Department (NOPD) Superintendent Eddie Compass. Many other government officials were criticized for their responses, especially New Orleans Mayor Ray Nagin, Louisiana Governor Kathleen Blanco, and President George W. Bush. Several agencies including the United States Coast Guard (USCG), National Hurricane Center (NHC), and National Weather Service (NWS) were commended for their actions. They provided accurate hurricane weather tracking forecasts with sufficient lead time.〔
(詳細はtropical wave and the remains of Tropical Depression Ten. It strengthened into Tropical Storm Katrina on the morning of August 24. The tropical storm moved towards Florida, and became a hurricane only two hours before making landfall between Hallandale Beach and Aventura on the morning of August 25. The storm weakened over land, but it regained hurricane status about one hour after entering the Gulf of Mexico, and it continued strengthening over open waters. On August 27, the storm reached Category 3 intensity on the Saffir-Simpson hurricane wind scale, becoming the third major hurricane of the season. An eyewall replacement cycle disrupted the intensification, but caused the storm to nearly double in size.〔 The storm rapidly intensified after entering the Gulf, growing from a Category 3 hurricane to a Category 5 hurricane in just nine hours. This rapid growth was due to the storm's movement over the "unusually warm" waters of the Loop Current.
Katrina attained Category 5 status on the morning of August 28 and reached its peak strength at 1800 UTC that day, with maximum sustained winds of and a minimum central pressure of . The pressure measurement made Katrina the fourth most intense Atlantic hurricane on record at the time, only to be surpassed by Hurricanes Rita and Wilma later in the season; it was also the strongest hurricane ever recorded in the Gulf of Mexico at the time. However, this record was later broken by Hurricane Rita.〔 The hurricane subsequently weakened, and Katrina made its second landfall at 1110 UTC on August 29 as a Category 3 hurricane with sustained winds of near Buras-Triumph, Louisiana. At landfall, hurricane-force winds extended outward from the center and the storm's central pressure was . After moving over southeastern Louisiana and Breton Sound, it made its third landfall near the Louisiana–Mississippi border with sustained winds, still at Category 3 intensity. Katrina maintained strength well into Mississippi, finally losing hurricane strength more than inland near Meridian, Mississippi. It was downgraded to a tropical depression near Clarksville, Tennessee, but its remnants were last distinguishable in the eastern Great Lakes region on August 31, when it was absorbed by a frontal boundary. The resulting extratropical storm moved rapidly to the northeast and affected eastern Canada.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』