Date of Award

5-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Earth and Environmental Studies

Thesis Sponsor/Dissertation Chair/Project Chair

Joshua C. Galster

Committee Member

Duke U. Ophori

Committee Member

Clement A. Alo

Abstract

The Hudson River watershed has undergone significant urbanization in some areas and reforestation in others during the past century. The watershed has also recently experienced extreme flood events, including from Hurricane Irene, which caused 49 deaths and an estimated $15.8 billion in damage nationally. However, it is unclear how much changes in land use and/or climate have caused shifts in river discharge and the contributions of runoff and baseflow to the river. Determining the existence and magnitude of these shifts are important for managing water resources. This study analyzes changes in daily flows and maximum annual discharge events at multiple recurrence intervals in the context of urbanization and climate change at 13 US Geological Survey river gages in the Hudson River watershed. Smaller, more frequent floods (i.e., the 2, 5, and 10-year floods) are increasing in magnitude at 9 of 13 sites and the larger, while infrequent floods (i.e., 50 and 100-year floods) are decreasing in magnitude at 10 of 13 sites. Increases in population density are correlated with increases in 2-year flood magnitudes at all 5 sites in the Hydroclimatic Data Network of gages with limited human influence. Baseflow is increasing at many sites, often in conjunction with increasing population density, and there are significant seasonal variations in these changes. This study documents the changes in discharge over time and suggests that hydrologists and water managers should consider factors that are significantly correlated with discharge changes (such as local land use) and should not assume that flood magnitude distributions are stationary.

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