DataStreme WES Week Eleven: 15-19 November 2004

• Molecular structure of liquid water studied -- Scientists at the University of California, Berkeley and the Lawrence Berkeley National Laboratory have used ultra-bright X-ray beams to study the hydrogen bond distortions in both liquid and solid water, in an effort to unravel the mysterious nature of water. [Lawrence Berkley National Laboratory]
• Where the rubber meets the wet road -- Physicists at the International Center for Theoretical Physics have been modeling the interface between vehicle tires and wet road surfaces in an attempt to explain more accurately why traction is reduced on wet roads. [Scientific American]
• Water quality at British beaches meets standards -- A report by the British Environmental Agency indicates that despite increased pollution from heavy summer rain, more than 98 percent of British beaches and bathing spots met European water quality standards. [ENN]
• Idaho utility wants customers to pay for cloud seeding -- The Idaho Power Company has requested state regulators to permit the company to charge its customers for three years of cloud seeding to alleviate the drought conditions across the state. [US Water News Online]
• River in nation's capital is polluted -- The Chesapeake Bay Foundation has given a failing grade to the Anacostia River that flows through the southeastern sections of the District of Columbia because of the polluted overflow of the District's sewerage system during heavy rain events. [US Water News Online]
• Details of US-Mexican water treaty studied -- A report issued earlier this year provides details of the complicated issues involved in the water wars along the Rio Grande River between Texas and the federal governments of the US and Mexico. [US Water News Online]
• California's flood protection questioned -- The two top flood control officials in California recently warned that the state's aging levees are in danger of failing, resulting in potential disaster for millions of residents, their residences and businesses. [USA Today]
• Recent precipitation aids drought situation in Arizona -- Above average precipitation during September and October across northern Arizona has allowed re-designation of the region's drought conditions from "extreme" to "severe". While some short term benefits are possible, experts caution that continued wet weather is needed for long-term relief. [USA Today]
• Computer models assist in power restoration-- Computer models developed at the Los Alamos National Laboratory are aiding various organizations to include the Department of Energy's Office of Energy Assurance and the Federal Emergency Management Agency (FEMA) to plan for electric power restoration in areas hit by hurricanes that have made landfall. [Los Alamos National Laboratory]
• Another legacy of Florida's hurricanes -- Agricultural officials in Florida report that this season's hurricanes that hit Florida have resulted in one of the largest outbreaks of citrus canker to hit the Sunshine State. The hurricane-force winds blew the contagious bacteria onto at least 11,000 citrus trees in one southwest Florida county, and affected trees in five other counties. [ENN]
• Focusing on the Columbia River Estuary -- A group of scientists and environmental science professionals will convene next week in Portland, OR to discuss the environmental and biological aspects of the Columbia River and its estuary. [Pacific Northwest National Laboratory]
• Monitoring European land use from space -- Data obtained from satellites are being collected to form an extensive survey of Europe's landscape as part of the Global Monitoring for Environment and Security initiative, which includes a partnership between the European Environment Agency and the European Space Agency. One of the aspects of this remote sensing effort would be improved information of flood risks for policy makers. [ESA]
• 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: Desertification

Desertification is one of the world's most pressing environmental issues, threatening the existence of more than a billion people who depend on the land for survival. In 1992, the United Nation's Conference on Environment and Development defined desertification as "land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climate variations and human activities." Through desertification, arable land is transformed into desert-like land, greatly reducing or eliminating the land's capacity to produce food. Desertification's impact on people dependent on subsistence farming and herding is food insecurity. Often, their only option to avoid famine is to migrate to urban areas.

According to U.N. estimates, desertification affects about 130 million hectares (320 million acres) of land worldwide, equivalent to the combined areas of France, Italy, and Spain. Portions of some 110 nations are impacted, including parts of the North American Great Plains, the Pampas of South America, the steppes of Asia, the Australia's "outback," and the edges of the Mediterranean. But by far the most widespread and severe impact is in Africa, where two-thirds of the continent's land area is desert or dry land. Almost three-quarters of Africa's dry-land agricultural area is degraded to some extent. Desertification is a very serious problem in Sub-Saharan Africa with its considerable year-to-year variability in seasonal rainfall and frequency of long-term drought (described on pages 83-84 of the DataStreme WES Textbook).

The systems approach is valuable in understanding desertification in that the process involves interactions of climate, Earth's land surface, the water cycle, and human activity. Desertification of dry lands accelerates during prolonged drought. Climate change can alter the frequency, duration, and intensity of drought and thereby contribute to soil desiccation. Although climate change may play an important role in desertification, a key factor is human mismanagement of the soil resource. Poverty and subsistence agriculture drives people to over-cultivate the land, quickly exhausting the soil's fertility. Overgrazing by livestock and deforestation exacerbate an already bad situation by removing the protective vegetative cover and exposing the topsoil to erosion by wind and running water. Winds can transport fine topsoil thousands of kilometers and sandstorms strip the leaves from plants and bury crops under dunes.

Land mismanagement also impacts the local climate and water budget, speeding up desertification. Without a vegetative cover, soil surface temperature rises, accelerating evaporation of water, depletion of soil moisture, and build up of salts in the soil. Less soil moisture means that more of the available heat is used for raising the air temperature through conduction and convection (i.e., sensible heating). In this way heat stress combines with moisture stress to cut into crop yields.

Concept of the Week: Questions

1. Through desertification, crop productivity [(declines) (increases)].
2. Human mismanagement of the soil resource [(is) (is not)] a key factor in desertification.

• 15 November 1900...A record lake-effect snowstorm at Watertown, NY produced 45 in. in 24 hrs. The storm total was 49 in. (14^th-15^th) (David Ludlum) (The Weather Channel)
• 18 November 1421...Wind-driven waves from an intense storm breached Dutch dikes, sweeping away 72 villages. At least 10,000 people died in "St. Elizabeth's flood." (Accord Weather Calendar)
• 18 November 1873...A severe storm raged from Georgia to Nova Scotia causing great losses to fishing fleets along the coast. In Maine, the barometric pressure dropped to 28.49 in. at Portland. (David Ludlum)
• 18-19 November 1921...A storm that produced 54 in. of snow, sleet and glaze in Oregon blocked the Columbia River Highway at The Dalles. Apart from traffic on the river itself, all transportation between Walla Walla, WA and Portland, OR came to a halt. Nine trains were stopped as railroads were blocked for days in both Washington and Oregon. (Intellicast) (David Ludlum)
• 19 November 1978...A waterspout came onshore to become a tornado near Muhio Wharf in Hilo Harbor on Hawaii's Big Island. Some industrial buildings lost their roofs. The proximity of the waterspout-tornado caused an airliner to change its landing approach to Hilo's airport. (Accord Weather Calendar)
• 19 November 1996...A 24-hour maximum precipitation record for the state of Oregon was established when 11.65 in. of rain fell at Port Orford. (NCDC)
• 21 November 1967...Excessive rains in southern California caused the most severe flooding and the most damaging mudslides in 33 years. Downtown Los Angeles received 7.96 in. of rain, and 14 in. fell in the mountains. (David Ludlum)
• 21 November 1987...Truk Island (Federated States of Micronesia at 7.4 degrees N, 151.7 degrees E) was struck by the rapidly intensifying Tropical Storm Nina, as winds gusted to 95 mph. Five died and most buildings were destroyed. A storm of such intensity so close to the equator is somewhat unusual. (Accord Weather Calendar)

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Prepared by AMS DataStreme WES Central Staff and Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
ã Copyright, 2004, The American Meteorological Society.