Doctoral Dissertation Research: Human long term adaptation to prehistoric ENSO-driven flooding

University Of Arkansas, Fayetteville AR

Investigators

Abstract

This doctoral dissertation research examines the impact of flooding generated by El Niño Southern Oscillation (ENSO) to understand the vulnerability of agricultural communities to extreme environmental variability. ENSO causes shifts in precipitation in arid coastal areas which can cause flash flooding and severe damage. This study emphasizes how changing floodplain morphology can make it more difficult for people to reduce their exposure to these floods. Flood events can alter the landscape to the extent that peoples’ capabilities to adapt to future events are limited. Consequently, knowledge about how to adapt to these events must be updated to deal with future potential hazards. Communities must continuously experience, observe, and communicate as they adjust over centuries and millennia to evolving floodplain conditions. Archaeology is well-suited to examine these processes of adapting to the evolution of river hazards. Attention to ancient settlement patterns and their respective floodplain environments reveals how societies mitigated potential flooding by finding elevated areas and generating flood-adapted infrastructure. Interpretations of this data inform modern mitigation efforts as flooding is an ongoing, dynamic risk experienced increasingly by populations worldwide. The interdisciplinary project consists of two parts: integrated hydrologic modeling to predict river behavior and a geological study of sediment sampled from past floods. The model uses historic stream flows, geospatial data, paleoclimatic reconstructions, and ethnohistoric accounts to determine ENSO flood hotspots. Additionally, paleochannels and remnant riverbeds are significant conduits of and contributors to overland flooding. Given their longevity in floodplain geomorphology, they serve as critical indicators for where past and future flooding might occur. Researchers study 650 previously surveyed archaeological sites in a single river valley to determine their exposure to increasing ENSO flood magnitudes in the floodplain and alluvial fan. The team utilizes geophysical and geochemical methods to evaluate soil characteristics in paleochannels to ascertain the impacts of flooding on the long-term stability and primary productivity of bankside landscapes. Leveraging multiple approaches to investigating flooding, this project contributes to archaeological methods and theories regarding flood risk, water resource management, and land use to explore past human-environment interactions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.