The monsoon history of mainland SE Asia is incredibly complex. ENSO, PDO, IPO, movement of the ITCZ all modulate the timing and amount of monsoon rains. Additionally the hydroclimate of the region is subject to frequent and intense tropical storms that can result in flooding and massive loss of life. Superimposed on this complex climate setting is a rich cultural history that has been impacted by monsoon breaks and droughts.
Several lines of research are currently being pursued. Many of these projects are in collaboration with Dr. Brendan Buckley-Lamont-Doherty Earth Observatory and colleagues at Vietnam National University.
Ao Tiên, Ba Be National Park, Northern Vietnam
Ao Tiên is a small collapse basin in the karst region of Ba Be National Park. It is the only documented carbonate lake thus far in Vietnam. I cored the lake in 2014 during a Fulbright sabbatical, retrieving the entire 650-year record. The high sedimentation rate permitted the reconstruction of effective moisture at biennial resolution, which resulted in identification of short-lived droughts identified in tree rings and ENSO related features. Data from the lake indicate a wet Little Ice Age likely as a result of persistent La Niña-like conditions. Although the record is short—it provides promise that other, now-filled, collapse basins exist in Vietnam and have similar excellent records.
- Stevens, LR, Buckley, BM, Kim, S, Hill, P, Doiron, K. (2018). Increased effective moisture in northern Vietnam during the Little Ice Age. Palaeogeography, Palaeoclimatology, Palaeoecology 511, 449-461. doi: 10.1016/j.palaeo.2018.09.011
Central Highlands Maar Lakes
The Central Highlands of Vietnam are home to multiple Plio-Pleistocene volcanic craters that host both perennial and ephemeral lakes. We are currently working on one lake, Ia M'He, which is mostly filled and quite shallow.
The lack of carbonates requires a new set of tools, namely compound-specific isotopes of leaf waxes and organic biomarkers. The preliminary record suggests that climate was exceptionally dry during the Last Glacial Maximum. This work is ongoing in collaboration with Indiana University and Hanoi University of Science.
- In progress - Kelsey Doiron: Deuterium isotopes and FAME-inferred climate change from Ia M'He, central Vietnam
- 2015 - Jeannie Amecuza: biogenic silica concentrations from Bien Ho, Vietnam
- 2014 - Traci La Rocco: anthropogenic effects of settlement on Ia M'He Lake, Vietnam
Central Highlands Flood Records
This project was funded by VNU-Hanoi University of Science. It culminated in the Masters theses of Ms. Tran Thi Thu Tran and Ms. Nguyen Oanh. The Central Highlands experiences catastrophic flooding every few years, largely as a result of catastrophic rainfall associated with tropical storms. Understanding the timing of past flooding events can also help us understand the frequency with which typhoons strike the Central Highlands—a region that exports significant amounts of coffee.
Coring the seasonally dry, Oxbow South in Kon Tum Province, Vietnam. Students from Hanoi University of Science and Dr. Thuyen of VNU-Ho Chi Minh City.
- 2016 - Trang Thu Tran (co-advised with Hanoi University of Science) Flood frequency along the Dak Bla River system, Central Highlands, Vietnam
- 2015 - Oanh Nguyen (co-advised with Hanoi University of Science) Drought events of the last 500 years in the Central Highlands of Vietnam based on treering analysis of Fokienia hodginsii.
- 2014 - Rane Anderson: Magnetic susceptibility of the sediment from an oxbow lake, Vietnam
Coastal Typhoon Project
This is an exploratory project to determine if we can reconstruct typhoon strikes along the coast of Vietnam. There are many dune-dammed lakes that serve as freshwater sources for villages and which may record landfall of major typhoons. I have cored two: Bau Cua and Bau Tro. Bau Cua has the most promising record.
- 2014 - Jenifer Leidelmeijer: reconstruction of paleotyphoon strikes in Bau Tro, Vietnam
- 2012 - Jessica Uglesich: storm strikes recorded in Bau Cua, Vietnam