Yi-Fu Tuan Lecture Archive

February 1 - The Hydrologic and Eco-Geomorphic Impacts of Dams
Francis J. Magilligan
Dartmouth College

Dams have major impacts on river hydrology, primarily through changes in the timing, magnitude, and frequency of low and high flows, ultimately producing a hydrologic regime differing significantly from the pre-impoundment natural flow regime. This talk presents the analysis of pre- and post-dam hydrologic changes from dams that cover the spectrum of hydrologic and climatic regimes across the United States. By using the established hydraulic relationships among flood frequency, flood magnitude, and river channel capacity, this research develops a scale-independent assessment of the hydrogeomorphic impacts of 21 dams across the United States that have broad ranges in function and contributing drainage area. On the basis of generalized extreme value (GEV) analysis of pre- and post-dam hydrologic records, this analysis indicates that the 2 yr discharge has decreased 60% following impoundment, exceeding the magnitude of climatically triggered discharge reductions occurring during the Holocene. Reductions in the frequency of the pre-dam 2 yr discharge have been equally profound. The pre-dam 2 yr flood has occurred on average twice per site, whereas statistical analysis indicates that it should have occurred 20 times. Furthermore, floods greater than bankfull have been essentially eliminated by dams, completely disconnecting the riparian zone from riverine influence. The analyses herein suggest that a critical threshold of disconnectivity exists and corresponds approximately to the pre-dam 5 yr flood. This similar recurrence probability exists independent of region, dam type, or catchment size. Moreover, the most significant changes across these sites occurred in minimum and maximum flows over different durations. For low flows, the 1-day through 90-day minimum flows increased significantly following impoundment. The 1-day through 7-day maximum flows decreased significantly across the sites. At monthly scales, mean flows in April and May tend to decline while mean flows in August and September increase. Other significant adjustments included changes in annual hydrograph conditions, primarily in the number of hydrograph reversals that has generally increased for almost all sites following impoundment. The number of high pulses has increased following impoundment but the average length declines. The mean rate of hydrograph rise and fall has declined significantly. These results indicate that the major pulse of dam construction during the previous century has modified hydrologic regimes on a nationwide scale, for large and small rivers.

February 22 - Space, time, and closed captioning: Geographies of technology, text, and labor
Greg Downey
University of Wisconsin-Madison

In this talk, based on his new book Closed captioning: Subtitling, stenography, and the digital convergence of text with television, Downey reveals the hidden information workers who mediate live audiovisual action and the production of written records. His work examines the relations between communication technology and human geography and explores the place of labor in a technologically complex and spatially fragmented world.

February 29 - Geographies of Risk and Difference: Environmental Justice, Science, and Superfund in and beyond Indian Country
Ryan Holifield
University of Wisconsin-Milwaukee

How does geography make a difference in the science-policy hybrid of human health risk assessment? In this paper I explore this question by tracing the negotiation of health risk parameters at the St. Regis Paper Company site, an unusual but significant Superfund hazardous waste site in the small city of Cass Lake, Minnesota. St. Regis is one of a very small number of sites in the US EPA’s Superfund remedial program that are located completely within the territorial boundaries of an American Indian reservation. In initial investigations of the site during the 1970s and 1980s, the territory of the Leech Lake Reservation was almost entirely ignored by state and federal agencies. But by the mid-2000s, after subsequent rounds of investigation revealed serious flaws in the site’s original cleanup, the geography of the reservation has come to play a central role in the ongoing remediation of St. Regis: both as a distinctive legal and political space of territorial jurisdiction and sovereignty, and as a unique cultural space distinguished by the practice of treaty-protected traditional tribal lifeways. A primary aim of this paper is to link the localized negotiations that made the Leech Lake Reservation “visible” as a space of risk and difference both to policy shifts in Washington and to technical developments in distant reservations.

March 7 - Fighting Yesterday while Facing Tomorrow: New Orleans and Hurricanes
Craig E. Colten
Louisiana State University

Resilience has entered the social science vocabulary from ecology. When applied to human communities, a distinction drawn is that human societies can learn from extreme events and make adjustments in the face of future events. This demands the preservation of the lessons between extreme events. How can environmental history and historical geography contribute to this enterprise? This talk uses New Orleans as a concrete case study for thinking about resilience in the face of technological and environmental systems whose rigidities make them vulnerable to extreme events like Hurricane Katrina.

March 28 - Si se Puede! Spaces of immigrant mobilizing for social justice
Helga Leitner
University of Minnesota

"Our freedom is because of those who came before us. They made an effort to secure these freedoms and we have a duty to do the same for ourselves and our children. I consider it my responsibility to fight injustice to immigrants today in the same way Dr. King fought for justice in the 1960's." (Surjit, IWFR Rider on the Washington State Bus) During the past decade immigrants, in alliance with labor unions, religious institutions and community organizations, have become pivotal in mobilizing for workers' and immigrant rights in US cities. Through numerous events and civic actions they are challenging various forms of oppression, domination and exclusion, seeking to supplant and rework currently hegemonic neoliberal/neoconservative discourses and practices, articulating alternative social, political and geographic imaginaries. These imaginaries emphasize equality and social justice, in terms of defending workers' rights and extending citizenship rights to all immigrants; recognition of and respect for racial and cultural diversity; and upholding civil rights and liberties for all. This paper examines one particular event, the Immigrant Workers Freedom Ride*, to interrogate the importance of space-time and emotions in this mobilization, as well as the challenges faced in negotiating across differences and construct a common political identity. * While limited in duration, the IWFR has come to assume more enduring importance as an important foundational event for the emergence of what is now known as the New Immigrant Rights Movement.

April 25 - Resilient but Vulnerable? The Challenge of Enhancing Adaptive Capacity in Rural Mexico
Hallie Eakin
University of California, Santa Barbara

What resources are needed to adapt to changing climatic conditions? Which populations will be able to adapt and which will have the most difficulties in meeting the challenge of unprecedented environmental and socioeconomic change? Many communities who rely directly on the natural environment for their survival have developed strategies to address the high risks and uncertainties associated with their existence in order to smooth consumption and avoid dangerous thresholds of change. Yet in the context of increasingly globalized economies, these same strategies are also associated with chronic poverty, a condition in which households seek livelihood stability at the expense of wealth. In essence, poor households often face a trade off between addressing multiple and simultaneous sources of chronic uncertainty and engaging in activities that may be more remunerative but also expose them to new shocks and stress. In this talk, I will present examples from case study research on farmers' responses to institutional, economic and environmental change in rural Mexico. These case studies illustrate how the efforts of relatively poor rural communities to minimize economic uncertainty may limit their flexibility to address climatic risk, and, conversely, how engaging in market opportunities can expose farm households to new livelihood volatility and undermine their resilience. Enhancing capacities to adapt to multiple stressors thus may require far more attention to the role of risk and the structural constraints on decision-making at the local level.

May 2 - Creative Geographies: Artists on the Ground
Emily Scott
University of California, Los Angeles

Emily Scott is an artist and educator whose work, within and outside of academia, explores intersections between art, geography, and the environment. In 2004, after many years as a park ranger naturalist, she founded the Los Angeles Urban Rangers, a collective that offers site-specific programming in and about Los Angeles and its everyday urban landscapes/ecologies. She is currently a doctoral candidate in art history at UCLA, writing a dissertation on landscape-based art from the 1960s-1970s and the wasteland spaces where it took place. During the 2007-2008 academic year, she is a Predoctoral Fellow at the Smithsonian American Art Museum as well as a Switzer Environmental Fellow and Carter Manny Awardee

May 9 - Giving Maps a Second Life with Digital Technologies
David Rumsey

David Rumsey will show how his increasing use of digital technologies and the Internet over the past decade has transformed his work as a historical map scholar and collector. Using imaging software, GIS, and popular applications like Google Earth and Second Life, Rumsey has given new life to old maps, both in their dissemination and our ability to analyze and understand them, thereby unlocking the information held in maps for use in a wide range of disciplines. He will discuss and demonstrate how he offers these software tools and a growing number of digitized maps themselves on his free public online map library. * The Trewartha Lecture will be followed by our 2008 Geography Department Student Award Presentation. All are invited to stay and support the achievements of our undergrads and grads! *