AUSTIN, Texas—Dr. Paul F. Hudson, assistant professor of geography in the College of Liberal Arts at The University of Texas at Austin, has been awarded a grant from the National Science Foundation to examine the deposits from the devastating summer floods on the Guadalupe River.
Hudson’s research specialty is fluvial geomorphology, which focuses on how water interacts with the earth’s surface to create landforms, such as floodplains. In particular, his research will provide insight on the role of large floods on the development of the Guadalupe River floodplain.
“Most floods in the Gulf Coast region are driven by hurricanes or winter storms,” Hudson said. “This flood was an anomaly because it was driven by a rather innocent, slow-moving low pressure system that settled over Texas, pumping up moisture from the Gulf of Mexico.”
Hudson noted that Central Texas is particularly vulnerable to large rainfall events due to the topography and thin soils. These are extremely high-energy flood events that are able to transport large amounts of sediment, which is what makes the otherwise clear waters of the Guadalupe River appear brown, and ultimately deposit large amounts of sediment to the floodplain. The sediments are deposited in layers, with each layer typically representing a single flood event. The layers of sediment serve as a recorder for floods, which can then be linked to climate.
“Because the recent flood was generated by a different type of climatic event it is important to study the flood deposits in detail so that we can ascertain how representative this event may be of the older floodplain deposits,” Hudson said.
Hudson and his students will measure the thickness of the deposits along survey transects; sample the sediments, which consist mainly of sand and mud; and then analyze the sediment samples of the sediment at the geomorphology laboratory within the Department of Geography at the university.
Hudson has also been studying the Mississippi River and how it has been affected over the last century due to engineering modifications. In addition to his Mississippi work, he has field sites in eastern Mexico and has recently started to work on the Amazon River in Brazil. His latest study on the Guadalupe River will provide his students the opportunity to gain experience investigating an important theoretical topic within a local context.
“A floodplain is a recorder of the environment,” Hudson said. “It provides critical information about how the landscape responded to past climate change, and also to historical human impacts, such as deforestation leading to accelerated rates of soil erosion.”
By analyzing the deposits of older floods, Hudson’s research will provide insight into long-term changes in the environment, such as how the floodplain topography has changed throughout the last several thousand years, but also how the floodplain topography influences recent patterns of sedimentation. In the case of the Amazon study, Hudson is having the floodplain sediments dated by radiocarbon analysis to better understand the evolution of the floodplain surface.
With the use of state-of-the-art technology in the field, such as global positioning systems and computer-assisted surveying equipment, Hudson is able to detect even the slightest change in floodplain elevation. Satellite imagery of the study sites are analyzed, in collaboration with the university’s Center for Space Research. Geographic information systems, a sophisticated database and mapping system, is then used to combine and analyze the information from the satellite imagery with the geospatial data collected in the field.
For more information contact: Dr. Paul Hudson, Department of Geography, 512-471-5116.
