WEEKLY WATER NEWS

DataStreme WES Week Nine: 26-30 March 2007

Water in the News:

(Thurs.) Satellites used to detect changes in glacial ice -- Scientists have been using data collected by the NASA/German Aerospace Center's Gravity Recovery and Climate Experiment (Grace) that measures variations in gravity to map changes in the mass of ice sheets and glaciers. Several scientists at the University of Colorado, Boulder have determined that the Greenland ice sheet has lost 40,000 to 66,000 gallons of water per year in this decade, which could result in an increase in global sea level by almost 0.02 inches per year. [NASA Earth Observatory]
(Thurs.) Climate history of tropical Africa reconstructed -- Scientists from the Royal Netherlands Institute for Sea Research and the University of Bremen have been studying the microfossils of soil bacteria in a marine sediment core taken from the outflow of the Congo River that has allowed them to reconstruct a temperature record for tropical Africa over the past 25,000 years. [Netherlands Organisation for Scientific Research]
(Thurs.) Ancient Brazilian shoreline seen from space -- A photograph taken by an astronaut on board the International Space Station shows the ancient shoreline (or strandplain) along the Brazilian coast. [NASA Earth Observatory]
(Thurs.) New homeport for NOAA ships -- Two NOAA research ships recently arrived at their new homeport on Ford Island in Oahu's Pearl Harbor. These ships, along with a third to be based there, will collect data for fisheries, coral reef and ocean research. [NOAA News]
(Thurs.) A rural water adequacy bill proposed -- State senators in the Arizona Senate recently approved a bill that would permit county and city governments in rural areas of the Grand Canyon State to restrict new home developments that lack the assurance of long-term water supplies of 100 years. [US Water News Online]
(Thurs.) Delta preservation plan developed -- Researchers at Louisiana State University along with coastal scientists from around the world have published a document entitled "Restoration of the Mississippi Delta: Lessons From Hurricanes Katrina and Rita" that focuses attention on the importance of the Mississippi Deltaic Plain and the need for its preservation following the disastrous 2005 hurricane season. [EurekAlert!]
(Tues.) Haze remains a problem in China -- Two images obtained from the MODIS sensor onboard NASA's Aqua satellite of the Beijing region of China using slightly different wavelengths show the large area of thick haze that had recently collected over this major metropolitan area. The increases in the haze, attributed to the rapid industrialization of China, have reduced visibility and have caused a decrease in rainfall especially over the hilly terrain. [NASA Earth Observatory]
(Tues.) NOAA hosts Science Fair -- Staff at the NOAA Science Center in Silver Spring, MD recently hosted a science fair for area students in grades four through six as a means of encouraging student interest in science careers. NOAA employees will also mentor students for three months. [NOAA News]
(Tues.) Old Nile records reveals a sun-climate link -- Scientists at the Jet Propulsion Laboratory and at California Institute of Technology who analyzed the Egyptian records of annual Nile River levels between 622 and 1470 AD near Cairo and the records of the number of aurorae sighted at the same time conclude that a convincing link between long-term solar and climate variability. [NASA Earth Observatory]
(Tues.) Coordination is needed for a national water quality monitoring network -- Based upon the 2004 final report of the U.S. Commission on Ocean Policy's and the U.S. Ocean Action Plan, NOAA recently released a report entitled "Linking Elements of the Integrated Ocean Observing System with the Planned National Water Quality Monitoring Network" that identifies the need for national water quality monitoring network. [NOAA News]
(Tues.) Prehistoric hurricane activity is uncovered -- A scientist at Louisiana State University who is an expert in paleotempestology has been analyzing sediment cores obtained from the Gulf Coast and reports that major catastrophic hurricanes (Category 4 or 5 on the Saffir-Simpson Intensity Scale) have hit each drill site approximately 10 to 12 times during the past 3800 years, meaning that the chances of a given Gulf location being struck by a major hurricane in a given year is approximately 0.3 percent. [EurekAlert!]
(Tues.) Mercury entering the ocean through groundwater flow -- Researchers at Woods Hole Oceanographic Institution have determined that a substantial amount of dissolved mercury has been entering the ocean through submarine groundwater discharge, at rates that appear to be greater than those from atmospheric and river sources. [Woods Hole Oceanographic Institution]
Becoming AWARE -- During this coming week of 25-31 March 2007, Michigan and Ohio will conduct their Severe Weather Awareness Week. These weeks are usually scheduled before the onset of the severe weather season in that particular state. If you live in either of these states, you should take time to become familiar with the various public affairs announcements issued by your local National Weather Service Office. In upcoming weeks, other states will observe Severe Weather Awareness weeks.
The Governor of Alaska, along with NOAA, has proclaimed this coming week (25-31 March 2007) as Tsunami Awareness Week in Alaska. The start of this week coincides with the 43^rd anniversary of the series of devastating tsunamis that struck southeastern Alaska following several earthquakes. [Governor's Office]
Earthquakes in western Pacific do not generate significant tsunamis --
- A magnitude 6.9 earthquake on Sunday in the Sea of Japan off the Japanese islands created a tsunami that propagated across the western North Pacific Ocean. Since the height of the tsunami was only six inches, the tsunami warning that had been issued was canceled. [CNN]
- Two powerful earthquakes, with magnitudes 7.2 and 6.2 were detected near the Pacific island nation of Vanuatu off the Australian continent on Sunday. A tsunami warning was issued, but no significant tsunami was reported. [CNN]
Space agency is involved in International Polar Year -- NASA scientists, including those at the Jet Propulsion Laboratory (JPL) and other NASA centers have joined colleagues from the US and more than 60 other countries in studying Earth's polar caps during the current International Polar Year (IPY) that commenced on 1 March and will conclude on 1 March 2009. JPL researchers are also studying the polar regions of the moon and Mars. [NASA Earth Observatory]
Avalanche danger high in Alaska's capital -- Recent rain along with record seasonal snowfall in Juneau, the capital of Alaska, has increased the threat of avalanches in the mountains surrounding the city. An urban avalanche forecasting office will be operating through April. [USA Today]
Airlines question FAA deicing requirements -- Recent long delays that occurred at large airports during winter storms of the last month may have been in part due to disagreements that developed between airlines and the Federal Aviation Administration (FAA) as to the length of time before an aircraft needs to be treated again with deicing agents before takeoff. [USA Today]
Recent levee report disputed by Corps of Engineers -- The US Army Corps of Engineers disputed a recently released report commissioned by the State of Louisiana that claimed the Corps was solely responsible for the decades of mistakes on the levee system in the New Orleans metropolitan area that resulted in floods following Hurricane Katrina. [USA Today]
Palestinian water projects affected by continued Middle East conflict -- Water projects funded by USAID that included the building of water and wastewater treatment facilities in Palestine have been terminated or under-funded because of the continued strife in the Middle East, including the rise to power of Hamas. [US Water News Online]
"Snowball Earth" theory dismissed -- A team from the United Kingdom and Switzerland have recently provided evidence of the existence of hot-cold cycles in the Cryogenian period (850-544 million years ago) that would refute the previously held "snowball Earth" theory that an ice age at that time cause Earth's ocean to freeze over. [EurekAlert!]
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 water 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

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

Historical Events:

26 March 1913...The Ohio River Basin flood reached a peak. Ten-inch rains over a wide area of the Ohio River Basin inundated cities in Ohio, drowning 467 persons, and causing $47 million in damage. The Miami River at Dayton reached a level 8 feet higher than ever before. The flood, caused by warm weather and heavy rains, was the second mostly deadly on record for the nation. (David Ludlum)
26 March 1997...Mudslide wiped out 164 feet of Canadian National rails in Fraser Canyon, British Columbia causing an eastbound freight train to plunge from the tracks. Two crewmen died and fears of chemical spill abound. (The Weather Doctor)
27-28 March 1964...The most powerful earthquake in US history, the Good Friday Earthquake, rocked south central Alaska, killing 125 people and causing $311 million in property damage, especially to the city of Anchorage. The earthquake in Prince William Sound, which had a magnitude of 9.2 on the Richter scale, caused some landmasses to be thrust upward locally as much as 80 feet, while elsewhere land sank as much as 8 feet. This earthquake and submarine landslides also created a tsunami that produced extensive coastal damage. A landslide at Valdez Inlet in Alaska generated a tsunami that reached a height of 220 feet in the inlet. A major surge wave that was approximately 100 ft above low tide caused major damage to Whittier (where 13 died) and other coastal communities in Alaska. The first wave took more than 5 hours to reach the Hawaiian Islands where a 10-foot wave was detected, while a wave that was 14.8 feet above high tide level traveled along portions of the West Coast, reaching northern California 4 hours after the earthquake. Nearly 10,000 people jammed beaches at San Francisco to view the possible tsunami, but no high-amplitude waves hit those beaches. Tsunami damage reached Crescent City in northern California. Tens of thousands of aftershocks indicated that the region of faulting extended about 600 miles. The Alaska Tsunami Warning Center was established in the wake of this disaster, with a mission to warn Alaskan communities of the threat from tsunamis. [See the 1964 Prince William Sound Tsunami page from the University of Washington.] (Accord's Weather Guide Calendar) ( US Coast Guard Historians Office)
27 March 1980...Waves to 20 ft and winds to 58 mph in the North Sea southwest of Stavanger, Norway led to the collapse of an oil rig accommodation platform. The deaths of 123 of the 212 people on the platform represents the world's worst drilling catastrophe. (Accord's Weather Guide Calendar)
28 March 1902...McMinnville, TN (elevation 900 ft) received 11.00 in. of precipitation, setting a 24-hour precipitation record for the Volunteer State. (National Climate Data Center).
28 March 1980...Although springtime was starting in the Rocky Mountains, the snow just kept on coming! One foot or more of snow fell over portions of eastern Colorado, southwest Nebraska, northwest Kansas and southeastern Wyoming. Winds reached 40 mph and Valentine, NE received 13 in. of snow. North Platte, NE checked in with 15 in. (Intellicast)
28 March 1998...Three Boy Scout troop members died when their sport utility vehicle was swept away as they tried to cross a running wash just north of Sunflower, AZ. (Accord's Weather Guide Calendar)
29 March 1886...Atlanta, GA was drenched with a record 7.36 in. of rain in 24 hours. (The Weather Channel)
29 March 1920...Clear Spring, MD received 31 inches of snow in 24 hours to establish a state record. (Sandra and TI Richard Sanders - 1987)
29 March 1980...Heavy rains produced mudslides in Natchez, MS. The slides covered two buildings on Silver Street, killing three people and injuring four. (Intellicast)
29 March 1989...Thunderstorms produced torrential rains in northeastern Texas and southwestern Arkansas. Longview, TX reported 14.16 in. of rain. More than 11 in. of rain at Henderson, TX caused a dam to give way, and people stranded in trees had to be rescued by boat. Total damage in northeastern Texas was estimated at $10 to $16 million. (The National Weather Summary) (Storm Data)
29-31 March 1848...An ice dam at the neck of Lake Erie and the entrance to the Niagara River between Fort Erie, ON and Buffalo, NY caused by wind, waves and lake currents stopped flow of water over Niagara Falls for 30 hours, commencing during the late hours of the 29^th. (Accord's Weather Guide Calendar) (The Weather Doctor)
31 March 2000...The water temperature of Lake Erie at Buffalo, NY was 39 degrees Fahrenheit on the last day of March, tying the maximum temperature for the date with that of 1998. Ice was present in 61 of 74 years on the 31^st, but this was third year in a row with open water. (Accord's Weather Guide Calendar)
1 April 1946...The Scotch Cap Lighthouse on Unimak Island in Alaska's Aleutian Islands was shaken by two earthquakes in a 27 minute span, then obliterated by a tsunami wave. The entire five-man crew was killed and the lighthouse antenna (105 ft above sea level) was washed away. Some debris was found 115 ft above sea level. The tsunami that propagated across the Pacific Ocean was responsible for more than 165 fatalities and over $26 million in damage. Many of the casualties were on the Hawaiian Islands, especially in Hilo on the Big Island. This tsunami was responsible for the development of the current Pacific Tsunami Warning System. (University of Washington) (Accord's Weather Guide Calendar) (US Coast Guard Historian's Office)