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The Great Flood of 1862 was the largest flood in the recorded history of Oregon, Nevada, and California, occurring from December 1861 to January 1862. It was preceded by weeks of continuous rains (or snows in the very high elevations) that began in Oregon in November 1861 and continued into January 1862. This was followed by a record amount of rain from January 9–12, and contributed to a flood which extended from the Columbia River southward in western Oregon, and through California to San Diego, and extended as far inland as Idaho in the Washington Territory, Nevada and Utah in the Utah Territory, and Arizona in the western New Mexico Territory. The event was climaxed by a warmer, more intense storm with much more rain that was much more serious, due to the earlier large accumulation of snow, now melted by the large turbulent heat fluxes into the snow over the lower elevations of the mountains. Throughout the affected area, all the streams and rivers rose to great heights, flooded the valleys, inundated or swept away towns, mills, dams, flumes, houses, fences, and domestic animals, and ruined fields. An early estimate of property damage was $10 million.〔(【引用サイトリンク】title=The Great Flood in California: Great Destruction of Property Damage $10,000,000 )〕 However, later it was estimated that approximately one-quarter of the taxable real estate in the state of California was destroyed in the flood. Dependent on property taxes, the State of California went bankrupt. The governor, state legislature, and state employees were not paid for a year and a half.〔(William H. Brewer, ''Up and down California in 1860-1864'', New Haven, Yale University Press, 1930, p. 243 ) Retrieved 23 October 2010.〕 Approximately 200,000 cattle drowned, and the state's economy shifted from ranching to farming. In recent years, the flood has held the attention of the United States Geological Survey and emergency planners, who used it as an example when modelling the impact of a similar event happening in modern-day California. The official name for such an event is "The Arkstorm", and it is unofficially called "The other big one".〔(【引用サイトリンク】title=ARkStorm: California’s other "Big One" )〕 == Background == The floods were likely caused by precipitation from atmospheric rivers, or narrow bands of water vapor about a mile above sea level that extend for thousands of kilometers. Prior to the flooding, Oregon had steady but heavier than normal rainfall during November and heavier snow in the mountains. The weather pattern that caused this flood was not from an El Nino, and from the existing Army and private weather records, it has been determined that the polar jet stream was to the north as the Pacific Northwest experienced a mild rainy pattern for the first half of December 1861. The jet stream then slid south and freezing conditions were reported at Oregon stations by December 25. Heavy rainfall began falling in California as the longwave trough moved down over the state, remaining there until the end of January 1862 and causing precipitation everywhere in the state for nearly 40 days. Eventually the trough moved even further south, causing snow to fall in the Central Valley and surrounding mountain ranges. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Great Flood of 1862」の詳細全文を読む スポンサード リンク
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