Maddie Holicky ’22 Assesses Land Use Changes

Maddie Holicky ’22 is an Environmental Geology major working with thesis advisor Jim Rougvie. She focuses on assessing land use changes using the legacy sediments in the James River Basin in Virginia.

My thesis project focuses on the land use change since colonial times within the James River Basin in western Virginia. This involves analyzing the sediments, which are more formally known as legacy sediments, from behind the dams that were constructed during the colonial period. Implementation of dams causes an increase of sedimentation which leads to an accumulation of sediments behind the dams. An accumulation of carbon and other chemicals from land uses occurs as well. When these dams are removed, these sediments remobilize, releasing harmful pollutants and excess carbon into the waterways.

Since the dams were removed, the banks behind them are easily accessible which makes collecting samples from vertical banks very easy. After the sediment was collected, it was analyzed for geochemical proxies that determine history of land uses in the area. These proxies include carbon and nitrogen isotopes, trace metals such as manganese, lead, and iron, and amount of total carbon. To understand these proxies, I have been plotting them stratigraphically according to the dates that the dams were in place. The variation in these specific proxies can inform us of shifts in the land plant species, increase of industrialization, and deforestation rates. Overall, this study aims to explain how human’s impact through land use changes can be cataloged within the legacy sediments and how those changes can affect sediment for hundreds of years after industrialization and evolution of agriculture.

By: Maddie Holicky'22
July 20, 2022

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