The Dust Bowl and Texas Playas

Changing land use in semi-arid regions has led to environmental disasters. In North America, the dust bowl of the 1930 destroyed farmland, led to mass migration out of the great plains, and led to new farming practices. Much of the great plains remains vulnerable to desertification. Sand dunes cover most of Nebraska, held in place by thin layer of vegetation. The Texas panhandle has many seasonal lakes, playas, that can be easily eroded by wind.

In Asia, changes in agricultural practices in Mongolia has led to severe dust storms. China is now implementing new programs to slow and stop the erosion.

Degraded land, stripped of its vegetation, trodden by the hooves of cattle or goats, turned by the plow, turns to dust and blows away, creating local and global problems. Today, vast regions of Mongolia are blowing away, creating dust storms that blanket Beijing and that cross the Pacific to drop dust on North America. In the 1930s devastating dust storms denuded the land in the North American great plains, creating the dust bowl, and causing the displacement of tens of thousand of farmers.

The Dust Bowl

On the cause of the 1930's Dust Bowl, a Science article by Schubert et al (2004).
During the 1930s, the United States experienced one of the most devastating droughts of the past century. The drought affected almost two-thirds of the country and parts of Mexico and Canada and was infamous for the numerous dust storms that occurred in the southern Great Plains. In this study, we present model results that indicate that the drought was caused by anomalous tropical sea surface temperatures during that decade and that interactions between the atmosphere and the land surface increased its severity. We also contrast the 1930s drought with other North American droughts of the 20th century.

Also read Long-Term Aridity Changes in the Western United States by Cook.
The western United States is experiencing a severe multiyear drought that is unprecedented in some hydroclimatic records. Using gridded drought reconstructions that cover most of the western United States over the past 1200 years, we show that this drought pales in comparison to an earlier period of elevated aridity and epic drought in AD 900 to 1300, an interval broadly consistent with the Medieval Warm Period. If elevated aridity in the western United States is a natural response to climate warming, then any trend toward warmer temperatures in the future could lead to a serious long-term increase in aridity over western North America.

The great plains on North America include large areas of wind-deposited sand and stabilized sand dunes. Destruction of vegetation on these deposits allows wind to begin to move the sand.

The plowing of the plains beginning in the early 20th century destroyed the original short-grass prairie, which was replaced by wheat fields, when drought began in the early 1930s, the wheat failed to grow, leaving bare fields at the mercy of the strong winds sweeping across the plains. Vast dust storms followed, destroying farms and driving 50,000 people a month from the land at the height of the Dust Bowl. Their story was told eloquently by John Steinbeck in Grapes of Wrath published in 1939.

Grapes of Wrath book cover. From Syracuse Library Special Collections Research Center Exhibition on Steinbeck's Grapes of Wrath: Bitter Fruit of the Great Depression.

25 million hectares of land were eroded by the wind by 1936. Some topsoil was deposited as far as Washington DC and 2000 kilometers out over the north Atlantic (Thomas).

Drought returned to the great plains from 1950-1956 causing further damage, dust storms, and soil erosion. To reduce future damage, the US Department of Agriculture began the Soil Bank Program that paid farmers to remove marginal drylands from cultivation. Soon afterwards, farmers began large-scale irrigation of their crops using water from the Ogallala aquifer (see Groundwater image of irrigated crops in Finny County, southwestern Kansas. As a result, drought that returned to the plains in the 1970s did not cause widespread dust storms and erosion.

Grassland management needs to involve grazing. Fall scene of season-long grazing at the end of one of the driest years on record in the Sandhills of Nebraska. Plants will be in an extreme weakened condition to begin plant growth next spring. From Water: Sandhills' Greatest Resource.

Pasture scene from the Sandhills of Nebraska taken in the late summer of one of the driest years on record. The grassland is part of a large herd, short duration system. From Water: Sandhills' Greatest Resource.

Texas Playas

Parts of the great plains are poorly drained because rain is sparse. In the these areas, water drains into seasonal lakes called playas. More than 60,000 playas are found in 155 counties across Colorado, Kansas, Nebraska, New Mexico, Oklahoma and Texas. The playas are used by millions of wildfowl (cranes, waterfowl, and shorebirds) as the migrate north and south through the plains. The playas are also recharge the Ogallala aquifer.

A playa in the Texas panhandle. From USGS Biology Activities in Texas. See also Texas Parks and Wildlife Panhandle Playa Lakes.

Dangerous Dust Storms

Dangerous Dust Storms on the Rise - China, an article from the June 2004 issue of Geotimes.

Terra satellite captured this image of a dust storm over the Taklimakan Desert, in western China on April 7, 2004.
From Dangerous Dust Storms on The Rise.

Soil Degradation

Wounding Earth's Fragile Skin, an Science article by Kaiser (2004) in Soils–Final Frontier, a 11 June 2004 special issue of Science (a 256 KB pdf file).

Soil degradation in all its nefarious forms is not a prelude to mass starvation, as analysts once feared. Nevertheless, it is eroding crop yields and contributing to malnourishment in many corners of the globe.

Sore spot. Erosion from timber cutting, overgrazing, and other human activities has left up to one-third of Haiti's land irreversibly damaged. From Wounding Earth's Fragile Skin.

The same issue also has an Interactive Map with the hot spots of land degradation/desertification/soil erosion.

References:

Thomas, Squires, and Glenn The North American Dust Bowl and Desertification: Economic and Environmental Interactions. In: World Atlas of Desertification.

Revised on: 8 December, 2008