EL NIÑO FLOODS AND CULTURE CHANGE: PREHISTORIC DISASTERS AND HUMAN RESPONSE IN COASTAL LOCUMBA VALLEY, TACNA, SOUTHERN PERU
MISSION: The Locumba Valley project aims to examine the historical correlation of catastrophic El Niño Southern Oscillation (ENSO) events with large-scale migration and culture change over the past four millennia along the Pacific coast of South America.
BACKGROUND: Researchers and public policy experts have been increasingly concerned with the effects of disasters and climate events on human societies of the Pacific Rim. No single climate phenomenon has had a more significant effect on past, present and future human occupation of the region than the ENSO. This project involves a pilot field survey in the coastal Locumba Valley in the department of Tacna in southern Peru. The plan is to build upon methods and results of a related long-term study in neighboring drainages that elucidated flood history, riparian response to flood events, and their correlation with ancient agrarian practice and settlement pattern. A crucial next question is: To what degree are these climate events and human responses universal phenomena, or unique to particular valleys and cultural settings?
The initial geoarchaeological survey covers the coastal Locumba Valley, a hyper-arid region in the northern fringes of the Atacama Desert, where precipitation totals less than 100 mm per year. These conditions are amenable to pedestrian survey to locate and sample preserved flood deposits from stratigraphic exposures. Using a combination of remote-sensing data analysis, hydraulic modeling, GPS and total station surveying, stratigraphic and particle size analyses, and radiocarbon dating, we will document the sequence, magnitude, frequency and geomorphic impacts of flood events and determine Late Holocene flood histories for the Coastal Rio Locumba and its tributaries. This project will be conducted in tandem with the ongoing systematic archaeological survey of the Proyecto Arqueológico Locumba (PAL), which has documented over 40 site components of Archaic, Formative, Tiwanaku, LIP, Inca and Spanish Colonial affiliation in the coastal Locumba and its Cinto and Salado tributaries. To contextualize flood events within archeological settlement history, we will cross-date flood events detected in river and tributary stratigraphy with shifts in human settlement and agricultural patterns. This interdisciplinary collaboration between geomorphological and archaeological investigations will permit us to build a chronology for major climatic events and understand human response through agrarian adaptation, migration and demographic change.