Kyle Hardage (Broach)

 

PhD Graduate

Department of Earth and Planetary Sciences

kbroach[at]ucsc[dot]edu

Research interests: paleohydrology, climate change, water resource management

Curriculum Vitae

 

Biography

I grew up outside of Nashville, Tennessee, and from a young age assisted in field work monitoring waters of the State with my mother who was an aquatic biologist. This early experience sparked curiosity in earth sciences, particularly hydrochemistry, leading to bachelor’s degrees in both chemistry and geology from Vanderbilt University in Nashville, TN. Undergraduate research included field work in Antarctica studying coastal sedimentology and provoked interest in graduate school. After taking several months to hike large sections of the Appalachian Trail, I moved to California in 2013 to begin graduate work in isotope geochemistry, climate change, and paleohydrology in tropical coastal lagoons to better understand how droughts impact regional water tables and water resource availability. Though I finished my doctorate in 2020, I am still engaged with the lab to continue learning about ongoing research in hydrology and geochemistry within California watersheds and aquifers. Currently, I work for the US Forest Service analyzing time series datasets to understand impacts of forest management on watershed health, and I am broadly interested in applied research to improve management practices of water resources under threat from climate change. I greatly enjoy travel and interdisciplinary collaboration, backpacking, hiking, baking and cooking, and woodworking.

Research

My research focused on reconstructing the ecology and climate of coastal ecosystems in the tropics. Though anthropogenic warming occurs globally, it is at the regional scale of climate where changes in wind, heat, and moisture affect hydrology, drought, and regional water resource availability. In the tropics, I sought to understand natural variability in the north-south migration of dominant moisture-rich atmospheric patterns, for this variability increases the uncertainty of predicted response of tropical precipitation to future anthropogenic warming. In this context, my dissertation focused on a tropical coastal lagoon in the Yucatan Peninsula and incorporated diverse types of data and statistical methods to interpret the paleoecology and paleoclimate of the region. The project consisted of analyzing the geochemistry of bulk carbonate sediments and microfossils from sediment cores taken from Celestun Lagoon, one of the largest estuaries in the Yucatan Peninsula. The diverse data set included stable and radiogenic isotopes (δ11B, δ13C, δ15N, δ18O, 87Sr/86Sr, 14C, 210Pb), trace elements (Li, Mg, B, Sr, Ba, U), population counts of foraminifera (shelled protists) and organic carbon sequestration,  which were all used to reconstruct lagoon salinity influenced by groundwater springs, seagrass habitat, lagoon geometry, and coastal geomorphic evolution. The work ultimately concluded that in tropical Yucatan lagoon sites, geomorphology greatly controls mixing between seawater and spring water as barrier islands migrate and alter pathways of water mixing in the lagoon. Though perhaps intuitive, this result is important because previous studies around the Caribbean that utilize coastal sites to reconstruct climate make no mention of geomorphic processes that alter the coastal sedimentary record on millennium timescales.