Senior tracks water patterns in Peru

Discovering geography leads to thesis subject

Published December 1, 2003; Category: STUDENTS

Geography, geology, anthropology: three fields that interested Dartmouth senior Rebecca Manners as an undergraduate. But when she had to choose a topic for her senior thesis, the choice was easy - all three.

Like an increasing number of college students across the country, Manners, a native of Tampa, Fla., has chosen to combine interests from across multiple disciplines in order to explore a subject she's passionate about. Entering Dartmouth, Manners says, she had a strong interest in anthropology and thought that would be her major. Then a funny thing happened:

"My first year I worked with Professor Frank Magilligan as an intern in the Women in Science Project, and I discovered geography," she said.

Fortuitously, Manners notes, Dartmouth is the sole member of the Ivy League with a geography department. The department, which Magilligan chairs, combined expertise in both physical and cultural geography, giving Manners the opportunity to explore land formation - specifically fluvial geomorphology, or the study of water's effect on landscape - while also satisfying her anthropological interests.

Manners's thesis combines these two fields while drawing on additional expertise from Dartmouth's geology department. With Magilligan's help she has identified a project in the Moquegua Valley of southern Peru, in the middle of the driest desert on earth. While this may seem a peculiar location for someone interested in water, Manners says it actually offers a perfect crucible for the study of the way water changes landscape - and culture.

"Though they may get just a few inches of rain a year, flooding in the Moquegua does occur and is affected by El Ni��o and snowmelt coming down from the Andes," Manners says. "The area available to farmers is very narrow on both sides of the river. When floods come through, they can wash away a significant portion of the arable land and that can cause significant landscape change, perhaps contributing to migration."

Manners has two goals for her thesis. First, she will use Geographic Information System (GIS) software to interpret recent Global Positioning System (GPS) data she helped collect. She will incorporate older data from aerial photographs to get a picture of erosion along the Moquegua over the last century. Then, she will relate this data to climate records for the area over a much longer time span and compare it with historical records of the activities of inhabitants in the area to get a sense of how they have been affected by floods.

"Very few studies actually document this relationship," Manners says. "This work could ideally apply to better understanding the role of the environment in the rise and fall of civilizations."

Last summer Manners, along with Magilligan, traveled to Peru to plot the current path of the river. They walked 26 miles of the river noting the boundary between channel and floodplain.

"Rebecca came to the project with a strong background in GIS and in physical geography," Magilligan said. "Despite never having done field work on this scale or in a foreign country, she quickly developed an expertise in geomorphic mapping. We were working with several colleagues from other universities, and they all assumed she was an advanced graduate student."

Now Manners is busy using aerial photographs of the area to track changes in the path of the river. She will then collate this data with information from ice-core samples from the Quelccaya ice cap high in the Andes, which provides a history of regional environmental conditions. She will also compare these geological and geographical records with historical data on the settlement and abandonment of the Moquegua valley.

"By looking at the loss of arable land due to contemporary floods and the time it takes for the land to be cultivated again, I can compare this to the larger historical record and get a sense of the long term effects of flooding on culture," she says.

Currently Manners spends several hours every day in the College's GIS lab looking at aerial photographs and inputting the data into the GIS system. She sees this project as a gateway to her future career.

"I'm planning on applying to graduate schools in geology," Manners says. "Being able to combine fields of study has been important in my studies and it was something I wouldn't have been able to do anywhere else."

BY JAMES DONNELLY