Special Talk at the Study School

Series Name School of Business's Civil Safety and Security Unit
Speaker Dr Maurits W. Ertsen
Type Lectures & Talks
When 25 Sep 2017, 05:45PM - 06:45PM
Venue Charles Wilson Building, 4th Floor
Open To Public
For Bookings Contact No booking is required. Contact details are: School of Business, 120 Fielding Johnson Building, Civil Safety and Security Unit University of Leicester University Road Leicester LE1 7RH


On the 25th of September, Dr Maurits W. Ertsen will present a talk on ‘Risk-taking versus sure-thing-taking: Changes in Hohokam irrigation over time'. Dr Ertsen is associate professor within the Water Resources Management group of Delft University of Technology, the Netherlands. The talk will be held on the 4th floor of the Charles Wilson Building as a part of the Study School for the MSc in Risk, Crisis and Disaster Management.

Abstract of the Talk:

The Hohokam civilization occupied areas along the middle Gila and Lower Salt rivers in the southwest of the (modern) USA roughly between 0 AD and the middle of the 15th century AD. The Hohokam are renowned for two things: their extensive irrigation canals and the apparent disappearance of Hohokam society after 1450. As such, the Hohokam is a popular symbol for the risks that societies run when they rely on a single source of food production and when they overstress that system. The Hohokam period is generally divided into four periods: the Pioneer (A.D. 450-750), Colonial (A.D. 750-950), Sedentary (A.D. 950-1150) and Classic (1150-1450) period. In the Classic period, Hohokam settlement retreated into more discrete clusters. After the Classic period, Hohokam society is supposed to have collapsed. Hohokam society faced immense fluctuations in annual water resource availability, fluctuations which would have interrupted the way institutions were established and maintained by Hohokam society. The settlement shift between Sedentary to Classic times occurred during a period of extremely low annual precipitation. Hohokam society’s dispersal after 1375 AD started under extremely low runoff conditions even though annual precipitation had not been extremely low. Our latest evidence suggests that the same period saw many more winter floods, suggesting the period was characterized by general low flows with every 5 to 10 years severe floods. This would have put stress on cooperative efforts – why invest time in repairing a system after a flood when it did not pay off the last time because of years of consecutive drought? There is also evidence that population migrated out of the cooperative structure during relatively wet periods only to come back later due to recurring dry conditions. This could have added further strain on the personal relationships and exacted another cost of personal nature on the coalition structure, weakening it over time. As such, the Hohokam might not be an example of a society that overstressed its resources, but as an example how difficult it is for a society to deal with risks at all, as meanings of risk change as much as the environment changes itself.

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