DataStreme WES Week Nine: 1-5 November 2004

• Atlantic storm batters Ireland -- A powerful storm that traveled across the North Atlantic late last week was accompanied by strong winds gusting to over 70 mph and heavy rain that produced coastal flooding. An Irish Ferries ship in the Irish Sea was kept at sea with more than 200 people for several hours because of the storm. [USA Today]
• Ethiopian drought could take a large toll -- A UN report warns that the lack of rain in southeastern Ethiopia during the last four years has created a drought that could threaten the lives of 4 million people, especially in the Somali region. [ENN]
• Cholera outbreaks linked to contaminated water sources -- Unsanitary conditions and the contamination of water sources have lead to cholera outbreaks in several African countries. In northern Uganda, at least two deaths have been attributed to the outbreak in a refuge camp. [ENN] In Senegal, two people died from this waterborne disease. [ENN]
• Lack of water could shut down power plant -- An electrical generating plant near Las Vegas, NV could be forced to remain closed after next year because a water use agreement had not been reached with Hopi Indians in northern Arizona that would permit water to be used to carry coal in a 273-mile slurry pipeline. [US Water News Online]
• Aquatic life could be harmed by household fragrances -- According to a National Institutes of Health study conducted by Stamford University researchers, the chemicals in the fragrant soaps and shampoos that enter the wastewater system can cause long-term damage to aquatic life since these chemicals can interfere with the animals ability to eliminate toxins. [EurekAlert!]
• Better identification of freezing drizzle conditions could help airlines -- A researcher at the National Center for Atmospheric Research has developed a system that would better identify freezing drizzle events at Denver International Airport that are costly to airlines because the drizzle is ingested into the idling jet engines causing damage. [UCAR News]
• Power from sewage-- Scientists at Pennsylvania State University have developed a microbial fuel cell that can serve as a clean energy source in addition to treating wastewater. [EurekAlert!]
• Microbes could cleanse contaminated groundwater -- Based upon an analysis of water from wells in central Illinois, geologists at the University of Illinois at Urbana-Champaign have discovered that some types of microbes can reduce the levels of arsenic in contaminated groundwater. [EurekAlert!]
• Egyptian temples to be protected -- A Swedish consulting firm will supervise a project aimed at protecting ancient temples in southern Egypt from the erosion caused by rising groundwater. [US Water News Online]
• Colorado water needs to be studied -- The Colorado Water Conservation Board is planning to undertake a major study to examine how the state can cope with its increased water needs. [US Water News Online]
• Global and US Hazards/Climate Extremes-- A review and analysis of the global impacts of various weather-related events, including drought, floods and storms during the current month. [NCDC]
• Global Water News Watch -- Other water news sources can be obtained through the SAHRA Project at the University of Arizona [SAHRA Project]
• Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Seiche

You probably remember as a child agitating the bath water so that it sloshed back and forth in the tub. (If you never did this as a child, there's still time.) You produced a seiche, a phenomenon first studied in Lake Geneva, Switzerland in the 1700s. A seiche (pronounced "say-sh") is a rhythmic oscillation of water in an enclosed basin (e.g., bathtub, lake, or reservoir) or a partially enclosed coastal inlet (e.g., bay, harbor, or estuary). With this oscillation, the water level rises at one end of a basin while simultaneously dropping at the other end. A seiche episode may last from a few minutes to a few days.

A seiche is a standing wave. Whereas wind-driven waves (pages 181-182 in your DataStreme WES textbook) are progressive in that they propagate through a body of water, standing waves are stationary. With progressive waves, crests and troughs travel along the wave surface but with standing waves, crests alternate vertically with troughs at fixed locations. For both progressive and standing waves, the restoring force is gravity.

With a typical seiche in an enclosed basin, the water level near the center does not change at all although that is where the water exhibits its greatest horizontal movement; this is the location of a node. At either end of an enclosed basin, vertical motion of the water surface is greatest (with minimal horizontal movement of water); these are locations of antinodes. The motion of the water surface during a seiche is somewhat like that of a seesaw: The balance point of the seesaw does not move up or down (analogous to a node) while people seated at either end of the seesaw move up and down (analogous to an antinode).

Go to the University of Delaware's Seiche Calculator at http://www.coastal.udel.edu/faculty/rad/seiche.html. Set the "Modal Number" to 1 and then press "Calculate" for a graphical simulation of a seiche in an enclosed basin.

Partially enclosed basins usually have a node located at the mouth (rather than near the center) and an antinode at the landward end. Go to the Seiche Calculator, set the "Modal Number" to 0.5 and then press "Calculate" for a simulation of a seiche in a basin open to the right. Furthermore, some basins are complex and have multiple nodes and antinodes; these can be simulated on the Seiche Calculator by selecting different values of "Modal Number" greater than one.

A seiche can be induced by wind, regional differences in air pressure, earthquakes, or tidal forces. For example, wind blowing persistently in the same direction down the long axis of a bay causes water to pile up at the downwind end of the bay. When the wind slackens, the water oscillates (as a seiche) back-and-forth from one end of the bay to the other until eventually the water calms to a horizontal surface. A line of thunderstorms moving eastward from Wisconsin in late May 1998 produced a seiche in Lake Michigan that killed several people by drowning at the southern end of the lake. Previous seiches have produced 8 to 10 ft waves on Lake Michigan. A tsunami generated a seiche in the harbor of Hilo, HI following a major earthquake in the Aleutian Islands on 1 April 1946.

The natural period of a seiche depends on the length and depth of the basin and generally ranges from minutes to hours: The period is directly proportional to basin length. For example, the natural period of a seiche in a small pond is considerably shorter than its period in a large coastal inlet. In addition, for the same basin, the natural period is inversely proportional to water depth; that is, the period shortens as water deepens. Using the Seiche Calculator, you may wish to experiment with different values of basin length and depth. Conversely, one can estimate the average depth of a lake by determining the period of the seiche and the length of the lake.

Usually a seiche in a lake or harbor is of little concern because the changes in water level are minor--often only a few centimeters. Under certain circumstances, however, a seiche may grow to great heights with serious consequences including flooding and damage to moored vessels. A seiche grows as a consequence of resonance, that is, when the period of the disturbance (e.g., wind, earthquake) matches the natural oscillation period of a specific basin. Recall again your youthful bathtub experience. By timing your rhythmic disturbance of the water to match the natural period of the tub (about one second), you were able to cause the seiche to build until the water splashed out of the tub and onto the floor. Through resonance, vibrations from the 1994 Northridge, CA earthquake caused swimming pools to overflow throughout Southern California. In bays open to the ocean, if the period of tidal forcing matches the natural period of the bay, resonance can greatly increase the tidal range.

Concept of the Week: Questions

1. Seiches are [(standing) (progressive)] waves.
2. The natural period of a seiche [(depends on) (is independent of)] the size of an enclosed basin.

• 1-6 November 1570... The All Saints Day Floods killed an estimated 400,000 people in Western Europe. (The Weather Doctor)
• 1 November 1861...A hurricane near Cape Hatteras, NC battered a Union fleet of ships attacking Carolina ports, and produced high tides and high winds in New York State and New England. (David Ludlum)
• 2 November 1946...A heavy wet snow began to cover the Southern Rockies. Up to three feet of snow blanketed the mountains of New Mexico, and a three-day snowstorm began at Denver, CO. By the time it ended, this storm had dropped 31 inches, making it the second greatest snowfall ever in city history and causing roofs to collapse. (David Ludlum)
• 2-4 November 1927...The "Great Vermont Flood" occurred as a two-day rain event totaling up to 15 inches at the higher elevations. The deluge put rivers in western New England over their banks and caused the worst flooding in the history of Vermont. Somerset, VT received 8.77 inches of rain to establish a 24-hour record for the state. (3^rd-4^th) The Winooski Valley was devastated. Eighty-four died in the Vermont town of Vernon. Flooding left up to eight to ten feet of water in downtown Montpelier. Across New England the flooding claimed 200 lives, caused $40 million in damage and halted traffic for days. (The Weather Channel) (Intellicast) (David Ludlum)
• 4-5 November 1966...The River Arno surged above flood stage and caused irreparable damage to much of the architectural and art treasure of Florence, Italy. Millions of historical library volumes were either damaged or destroyed. More than 15,000 vehicles were also destroyed. (Accord Weather Calendar)
• 5 November 1977...A slow moving storm produced five to nine inch rains across northern Georgia causing the Toccoa Dam to burst. As the earthen dam collapsed, the waters rushed through the Toccoa Falls Bible College killing three persons in the dorms. Thirty-eight persons perished at a trailer park along the stream. Eighteen bridges were washed out in Madison County. (David Ludlum)
• 5 November 1987...Heavy rains in California's Death Valley National Park washed out many park roads. As much as 1.20 in. of rain fell at Scotty's Castle, compared with the annual rainfall average of 2.28 in. Up to 8000 people attending a recreational encampment were stranded. (Accord Weather Calendar)
• 6 November 1994...Downtown San Francisco, CA was drenched with 6.19 in. of rain in 24 hrs to set an all-time record for the city.
• 6-13 November 1969...Severe ice storm between Quebec City and Manicouagan River power dams in Quebec caused over $1.5 million damage to transmission lines and towers. Over 30 transmission towers under construction were brought down. (The Weather Doctor)
• 8 November 1876...Two days of rain dumped 4.9 in. on Fredericton, New Brunswick. The rail line near Lawrence Station was washed out causing the derailment of the morning St. John-Fredericton run. (The Weather Doctor)
• 8 November 1914...On this date the longest "official" rain-free time span on record for the U.S. of 767 days ended in Bagdad, CA. Some meteorologists question the accuracy of this record kept by railroad employees at that time. (Accord Weather Calendar)
• 9 November 1913...The "Freshwater Fury," a rapidly deepening midlatitude cyclone, caused unpredicted gales on the Great Lakes. Seventeen ships, including eight large ore carriers on Lake Erie sank drowning 270 sailors. Cleveland, OH reported 17.4 in. of snow in 24 hrs, and a storm total of 22.2 in., both all-time records for that location. During the storm, winds at Cleveland averaged 50 mph, with gusts to 79 mph. The storm produced sustained winds of 62 mph at Port Huron, MI, wind gusts to 80 mph at Buffalo, NY and buried Pickens, WV under three feet of snow. (9^th-11^th) (David Ludlum) (The Weather Channel)
• 9 November 1932...An unnamed hurricane struck Cuba, with winds reaching approximately 210 mph at Nuvitas. However, a storm surge was the main killer of 2500 of the 4000 residents of Santa Cruiz del Sur. Essentially no storm records exist, as the observer drowned, with records and instruments washed away. (Accord Weather Calendar)
• 9-11 November 2001...More than the average month's total (3.7 inches) of heavy rains fell on Algiers, Algeria in just a few hours. The resulting massive floods and mudslides devastated northern Algeria and killed more than 700 people causing nearly $300 million worth of damage. (The Weather Doctor)

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URL: WES/news.html
Prepared by AMS WES Central Staff and Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2004, The American Meteorological Society.