An ARkStorm (for Atmospheric River 1,000) is a "megastorm" proposed scenario based on repeated historical occurrences of atmospheric rivers and other major rain events first developed and published by the Multi-Hazards Demonstration Project (MHDP) of the United States Geological Survey (USGS) in 2010 [1] and updated as ARkStorm 2.0 in 2022. [2]
The ARkStorm 1.0 scenario describes an extreme storm that devastates much of California, causing up to $725 billion in losses (mostly due to flooding), and affecting a quarter of California's homes. The scenario projects impacts of a storm that would be significantly less intense (25 days of rain) than the California storms that occurred between December 1861 and January 1862 (43 days). That event dumped nearly 10 feet (3.0 m) of rain in parts of California. [3] [4]
USGS sediment research in the San Francisco Bay Area, Santa Barbara Basin, Sacramento Valley, and the Klamath Mountain region found that "megastorms" have occurred in the years: 212, 440, 603, 1029, c. 1300, 1418, 1605, 1750, 1810, and, most recently, 1861–1862. Based on the intervals of these known occurrences, ranging from 51 to 426 years, for a historic recurrence of, on average, every 100–200 years. [3]
Geologic evidence indicates that several of the previous events were more intense than the one in 1861–1862, particularly those in 440, 1418, 1605, and 1750, each of which deposited a layer of silt in the Santa Barbara Basin more than one inch (2.5 cm) thick. The largest event was the one in 1605, which left a layer of silt two inches (5 cm) thick, indicating that this flood was at least 50% more powerful than any of the others recorded.
The conditions built into the scenario are "two super-strong atmospheric rivers, just four days apart, one in Northern California and one in Southern California, and one of them stalled for an extra day". [5]
The ARkStorm 1.0 scenario would have the following effects:
This update, [7] with parts of the research on impacts still ongoing,[ when? ] has examined how climate change is expected to increase the risk of severe flooding from a hypothetical ARkStorm, with runoff 200% to 400% above historical values for the Sierra Nevada in part due to a decrease in the portion of precipitation that falls as snow, as well as an increase in the amount of water that storms can carry. The likelihood of the event outlined in the ARkStorm scenario is now once every 25–50 years, with projected economic losses of over $1 trillion (or more than five times that of Hurricane Katrina). [8]
| Odds of Occurring | ||||||
|---|---|---|---|---|---|---|
| Scenario | Annual Risk | 1920 Risk | 2071–2080 Risk (worst case with RCP 8.5) | Days | Precipitation | Damage (if it happened today) |
| Great Flood of 1862 | 1.2–1.6% | 0.5–0.7% | 3.4%–4.8% | 43+ | 10 feet (3.0 metres) | |
| ARkStorm | 2–4% | 25+ | US$1 trillion+ (2010 estimate in 2022 dollars) | |||
Current flood maps in the U.S. rarely take recent projections from projects like ARkStorm into account, especially FEMA's maps, which many decision-makers have relied on. [9] Land owners, flood insurers, governments and media outlets often use maps like FEMA's that still fail to represent many significant risks due to: 1) using only historical data (instead of incorporating climate change models), 2) the omission of heavy rainfall events, and 3) lack of modeling of flooding in urban areas. More robust and up-to-date models, like the First Street Foundation's riskfactor.com, [10] should better represent true flood risk though it is unclear if that model, for example, incorporates any ARkStorm science.
Government agencies may decide how much risk to accept, and how much risk to mitigate. The Netherlands' approach to flood control, for example, plans for 1 in 10,000 year events in heavily-populated areas [11] and 1 in 4,000 year events in less well-populated areas.
A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant concern in agriculture, civil engineering and public health. Human changes to the environment often increase the intensity and frequency of flooding. Examples for human changes are land use changes such as deforestation and removal of wetlands, changes in waterway course or flood controls such as with levees. Global environmental issues also influence causes of floods, namely climate change which causes an intensification of the water cycle and sea level rise. For example, climate change makes extreme weather events more frequent and stronger. This leads to more intense floods and increased flood risk.
A natural disaster is the very harmful impact on a society or community after a natural hazard event. Examples of natural hazard events are avalanches, blizzards, droughts, dust storms, earthquakes, floods, hails, heat waves, impact events, landslides, sinkholes, tornadoes, tropical cyclones, tsunamis, volcanic activity and wildfires. A natural disaster can cause loss of life or damage property. It typically causes economic damage. How bad the damage is depends on how well people are prepared for disasters and how strong the buildings, roads, and other structures are. Scholars have been saying that the term natural disaster is unsuitable and should be abandoned. Instead, the simpler term disaster could be used. At the same time the type of hazard would be specificed. A disaster happens when a natural or human-made hazard impacts a vulnerable community. It results from the combination of the hazard and the exposure of a vulnerable society.
The Federal Emergency Management Agency (FEMA) is an agency of the United States Department of Homeland Security (DHS), initially created under President Jimmy Carter by Presidential Reorganization Plan No. 3 of 1978 and implemented by two Executive Orders on April 1, 1979. The agency's primary purpose is to coordinate the response to a disaster that has occurred in the United States and that overwhelms the resources of local and state authorities. The governor of the state in which the disaster occurs must declare a state of emergency and formally request from the President that FEMA and the federal government respond to the disaster. The only exception to the state's gubernatorial declaration requirement occurs when an emergency or disaster takes place on federal property or to a federal asset—for example, the 1995 bombing of the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, or the Space Shuttle Columbia in the 2003 return-flight disaster.
Pineapple Express is a specific recurring atmospheric river both in the waters immediately northeast of the Hawaiian Islands and extending northeast to any location along the Pacific coast of North America. It is a non-technical term and a meteorological phenomenon. It is characterized by a strong and persistent large-scale flow of warm moist air, and the associated heavy precipitation. A Pineapple Express is an example of an atmospheric river, which is a more general term for such relatively narrow corridors of enhanced water vapor transport at mid-latitudes around the world.
The National Flood Insurance Program (NFIP) is a program created by the Congress of the United States in 1968 through the National Flood Insurance Act of 1968. The NFIP has two purposes: to share the risk of flood losses through flood insurance and to reduce flood damages by restricting floodplain development. The program enables property owners in participating communities to purchase insurance protection, administered by the government, against losses from flooding, and requires flood insurance for all loans or lines of credit that are secured by existing buildings, manufactured homes, or buildings under construction, that are located in the Special Flood Hazard Area in a community that participates in the NFIP. U.S. Congress limits the availability of National Flood Insurance to communities that adopt adequate land use and control measures with effective enforcement provisions to reduce flood damages by restricting development in areas exposed to flooding.
Typhoon Vera, also known as the Isewan Typhoon, was an exceptionally intense tropical cyclone that struck Japan in September 1959, becoming the strongest and deadliest typhoon on record to make landfall on the country as a Category 5 equivalent storm. The storm's intensity resulted in catastrophic damage of unparalleled severity and extent, and was a major setback to the Japanese economy, which was still recovering from World War II. In the aftermath of Vera, Japan's disaster management and relief systems were significantly reformed, and the typhoon's effects would set a benchmark for future storms striking the country.
Disaster risk reduction aims to make disasters less likely to happen. The approach, also called DRR or disaster risk management, also aims to make disasters less damaging when they do occur. DRR aims to make communities stronger and better prepared to handle disasters. In technical terms, it aims to make them more resilient or less vulnerable. When DRR is successful, it makes communities less the vulnerable because it mitigates the effects of disasters. This means DRR can make risky events fewer and less severe. Climate change can increase climate hazards. So development efforts often consider DRR and climate change adaptation together.
The Great Flood of 1862 was the largest flood in the recorded history of California, Oregon, and Nevada, inundating the western United States and portions of British Columbia and Mexico. It was preceded by weeks of continuous rains and snows 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 that extended from the Columbia River southward in western Oregon, and through California to San Diego, as well as extending as far inland as the Washington Territory, the Utah Territory, and the western New Mexico Territory.
An atmospheric river (AR) is a narrow corridor or filament of concentrated moisture in the atmosphere. Other names for this phenomenon are tropical plume, tropical connection, moisture plume, water vapor surge, and cloud band.
The California flood of 1605 was a massive flood that submerged large portions of present-day California. The megaflood was a result of sustained major rain storms across the region, enhanced by an unusually powerful atmospheric river. The flooding affected the indigenous peoples of California, in pre-industrial advancement populations.
Coastal hazards are physical phenomena that expose a coastal area to the risk of property damage, loss of life, and environmental degradation. Rapid-onset hazards last a few minutes to several days and encompass significant cyclones accompanied by high-speed winds, waves, and surges or tsunamis created by submarine (undersea) earthquakes and landslides. Slow-onset hazards, such as erosion and gradual inundation, develop incrementally over extended periods.
Public Law 113-2, containing Division A: Disaster Relief Appropriations Act, 2013 and Division B: Sandy Recovery Improvement Act of 2013 is a U.S. appropriations bill authorizing $60 billion for disaster relief agencies. The Budget Control Act of 2011 (BCA), had authorized only disaster spending and emergency spending to exceed established spending caps. While emergency spending is not subject to the caps in the BCA, spending for disaster relief is calculated by taking the average of the previous ten years disaster relief spending, excluding the highest and lowest spending years.
The Homeowner Flood Insurance Affordability Act of 2013 is a bill that would reduce some of the reforms made to the federal flood insurance program that were passed two years prior. The bill would reduce federal flood insurance premium rates for some properties that are sold, were uninsured as of July 2012, or where coverage lapsed as a result of the policyholder no longer being required to maintain coverage.
Megastorm may refer to:
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Fourth National Climate Assessment (NCA4) 2017/2018 is a 1,500 page two-part congressionally mandated report by the U.S. Global Change Research Program (USGCRP)—the first of its kind by the Trump administration, who released the report on November 23, 2018. The climate assessment process, with a report to be submitted to Congress every four years, is mandated by law through the Global Change Research Act of 1990. The report, which took two years to complete, is the fourth in a series of National Climate Assessments (NCA) which included NCA1 (2000), NCA2 (2009), and NCA3 (2014).
The effects of climate change on extreme weather events is requiring the insurance industry in the United States to recalculate risk assessments for various insurance policies. From 1980 to 2005, private and federal government insurers in the United States paid $320 billion in constant 2005 dollars in claims due to weather-related losses while the total amount paid in claims annually generally increased, and 88% of all property insurance losses in the United States from 1980 to 2005 were weather-related. Annual insured natural catastrophe losses in the United States grew 10-fold in inflation-adjusted terms from $49 billion in total from 1959 to 1988 to $98 billion in total from 1989 to 1998, while the ratio of premium revenue to natural catastrophe losses fell six-fold from 1971 to 1999 and natural catastrophe losses were the primary factor in 10% of the approximately 700 U.S. insurance company insolvencies from 1969 to 1999 and possibly a contributing factor in 53%. From 2005 to 2021, annual insured natural catastrophe losses continued to rise in inflation-adjusted terms with average annual losses increasing by 700% in constant 2021 dollars from 1985 to 2021.
The 1997 California New Years Floods resulted from a series of winter storms, from December 26 to January 3 of 1997, fed with tropical moisture by an atmospheric river. It impacted Northern California, resulting in some of the most devastating flooding since the Great Flood of 1862. Similarly to the 1862 event, the flooding was a combined effect of heavy rainfall and excessive snowmelt of the relatively large early-season Sierra Nevada snowpack. The resulting flooding in the Central Valley and other low-lying areas forced over 120,000 people from their homes and caused over $2 billion in property damage alone. 48 out of California's 58 counties were declared disaster areas with many streamflow gauge stations in these areas recording return intervals of over 100 years. It would take months for the worst-hit areas to recover fully.