Exploring Groundwater Systems near Kaiwi Coast, Oahu, Hawaii: Haozhe (Jason) Zhang
Article and photos courtesy of American Geophysical Union – Near Surface Geophysics July 2019 Newsletter
Haozhe (Jason) Zhang is a first-year master’s student in the Department of Geology at the University of Kansas (KU). He obtained his B.S. in petroleum engineering from KU and is currently working with Dr. Chi Zhang on hydrogeophysics. This summer, Jason had a great opportunity to attend a hydrogeophysics field school organized by Dr. Niels Grobbe, assistant research professor at the University of Hawai‘i at Mānoa (UHM). The 3-week field course offered a great opportunity for students to be trained with multiple geophysical methods: self-potential, nodal-based true 3-D Electrical Resistivity Tomography (ERT), and ambient noise–based seismic. Dr. Niels Grobbe, along with Dr. Stéphanie Barde-Cabusson (a postdoc at UHM) and Dr. Aurélien Mordret (a postdoc at MIT), instructed each of the methods with workflow of a geophysical survey including data acquisition, applying geophysical tools in the field, data processing, and integrating the processed data from all methods to hydrological modeling. Students were able to explain the fundamentals, to perform field data design and instrument deployments and data processing for each of the methods at the end of the course.
During the first week of the summer school, Jason not only had theory lectures and some fieldwork on some of the geophysical methods but also was focused on learning the geology of volcanic environments and Hawaiian anthropology. A woman from Maunalua.net depicted the Hawaiian local history with pictures shown to students and made me feel that I was present at the scene. Dr. Peter J. Mouginis-Mark from the University of Hawai‘i at Mānoa guided a geological walk on the lighthouse trail next to the study site and then went on a hydrological excursion at UHM Lyon Arboretum. It was important to understand the changes and developments of groundwater that are strongly associated with human activities on the islands.
The second and third week of the course consisted mainly of fieldwork, theory, data processing, and hydrological modeling (from Dr. Aly El-Kadi). On the field days, we deployed different instruments for different geophysical methods. To acquire good quality data, both the precise measurement and accurate location of instrument deployment were required at the field site. As good quality data were retrieved from three different methods, we conducted processing and analysis of the field data. Some of the data processing was done using several commercially available software programs; for the ambient seismic method, a self-coded program by Dr. Aurélien Mordret was also used for part of the signal processing. By combining the processed and analyzed data with local geology information and field condition observations, we were able to make our initial interpretation of the groundwater system at the Kaiwi coast.
Both the fieldwork and the data processing days were full of challenges and adventures. Through the condensed 3-week summer field school at the University of Hawai‘i at Mānoa, I was exposed to and gained experience in three different geophysical methods (in both field data acquisition and data processing and interpretation). What’s more, I enjoyed my time exploring the island and built my network with some current geophysical researchers and some future geophysicists.