Geog 212: Tutorial on Floodplain Hazards

Background

Newspaper headlines during the summer of 2002 publicized the plight of prairie farmers whose fields of wheat and canola withered in the sun, and whose cattle were threatened with starvation as a result of failure of the hay crop. The drought that caused these agricultural failures is a recurrent problem in the North American Great Plains.
The earliest explorers of these prairie landscapes would not have been surprised to learn of these agricultural failures. John Palliser, who journeyed through western Canada from 1857-1860, pronounced the prairies to be near-desert. Henry Hind, visiting southern Saskatchewan in 1858, wrote: "A proper appreciation and use of facts will convince the most sanguine that the larger portion of this area is, in its present state, unfit for permanent habitation of man, on account of climate, soil, and a lack of fuel. Nevertheless, the prairies were intensively settled by homesteaders in the wet years of the last decades of the nineteenth century, only to suffer episodes of depopulation since then, particularly in the 1910's and 1930's, as a result of drought.
Prior to advances in dryland farming techniques in the mid-20th century, "fifteen inches [about 380 mm] of rainfall was the make-or-break rule of thumb". Much less than that, and the topsoil turned to dust, and the hopper squadrons darkened the sky around the edge of the sun".

TASKS
In this workshop you are asked to examine a long-term precipitation record from one weather station on the northern Great Plains, and compare it to records from other regions, and to think about the socio-economic implications of these records.

You should consider the following climatological questions:

What is the regional precipitation pattern on the northern Great Plains?

How prone, therefore, are areas of the prairies to severe drought? (which we can define as less than 380 mm annual rainfall)

Where do the stations fit into this regional pattern?

Is there a discernable long-term temporal pattern of 'wets' and 'drys' at your station, or is the pattern more-or-less random?

Has 'global warming' in the late 20th century had an influence on drought recurrence or intensity at this station?

Is El Nino "good news"? What do Garnett (2002) and Basiji and Gough (2002) suggest? Do you agree from an examination of a single station record?

Do the prairies suffer concurrent drought? Does, for instance, the 'wet-dry' pattern in northern Alberta follow the same rhythm as that in Montana or the Dakotas?

Secondly, consider the following socio-economic questions:
If prairie droughts can be predicted, what precautions, if any, could be taken?

Should we subsidize agriculture in drought-prone areas? (e.g. should Alberta have awarded a compensation package of $340 million to drought-stricken farmers in 2002?)

What other mitigation strategies could be adopted?

Handouts
Average annual precipitation maps of northern Great Plains

Precipitation records from the following weather stations:
Glendive, Montana
Edmonton, Alberta
Medicine Hat, Alberta
Pierre, South Dakota
Winnipeg, Manitoba

Palmer Drought severity indices:
Eastern Montana (Glendive area);
South Dakota (Pierre area)

El Nino/La Nina impact maps

Southern Oscillation Index (1875-2000)


	Geog. 312: Natural Hazards

	Drought exercise
			(return to assignments)

	Background Newspaper headlines during the summer of 2002 publicized the plight of prairie farmers whose fields of wheat and canola withered in the sun, and whose cattle were threatened with starvation as a result of failure of the hay crop. The drought that caused these agricultural failures is a recurrent problem in the North American Great Plains. The earliest explorers of these prairie landscapes would not have been surprised to learn of these agricultural failures. John Palliser, who journeyed through western Canada from 1857-1860, pronounced the prairies to be near-desert. Henry Hind, visiting southern Saskatchewan in 1858, wrote: "A proper appreciation and use of facts will convince the most sanguine that the larger portion of this area is, in its present state, unfit for permanent habitation of man, on account of climate, soil, and a lack of fuel. Nevertheless, the prairies were intensively settled by homesteaders in the wet years of the last decades of the nineteenth century, only to suffer episodes of depopulation since then, particularly in the 1910's and 1930's, as a result of drought. Prior to advances in dryland farming techniques in the mid-20th century, "fifteen inches [about 380 mm] of rainfall was the make-or-break rule of thumb". Much less than that, and the topsoil turned to dust, and the hopper squadrons darkened the sky around the edge of the sun". TASKS In this workshop you are asked to examine a long-term precipitation record from one weather station on the northern Great Plains, and compare it to records from other regions, and to think about the socio-economic implications of these records. You should consider the following climatological questions: What is the regional precipitation pattern on the northern Great Plains? How prone, therefore, are areas of the prairies to severe drought? (which we can define as less than 380 mm annual rainfall) Where do the stations fit into this regional pattern? Is there a discernable long-term temporal pattern of 'wets' and 'drys' at your station, or is the pattern more-or-less random? Has 'global warming' in the late 20th century had an influence on drought recurrence or intensity at this station? Is El Nino "good news"? What do Garnett (2002) and Basiji and Gough (2002) suggest? Do you agree from an examination of a single station record? Do the prairies suffer concurrent drought? Does, for instance, the 'wet-dry' pattern in northern Alberta follow the same rhythm as that in Montana or the Dakotas? Secondly, consider the following socio-economic questions: If prairie droughts can be predicted, what precautions, if any, could be taken? Should we subsidize agriculture in drought-prone areas? (e.g. should Alberta have awarded a compensation package of $340 million to drought-stricken farmers in 2002?) What other mitigation strategies could be adopted? Handouts Average annual precipitation maps of northern Great Plains Precipitation records from the following weather stations: Glendive, Montana Edmonton, Alberta Medicine Hat, Alberta Pierre, South Dakota Winnipeg, Manitoba Palmer Drought severity indices: Eastern Montana (Glendive area); South Dakota (Pierre area) El Nino/La Nina impact maps Southern Oscillation Index (1875-2000)