59 Interpreting Sedimentary Records of Past Changes in Climate and Ecology

Tuesday, 25 March 2014
8:00 AM - 12:00 PM
Heritage Salon D

PUTTING HURRICANE IRENE SEDIMENTS IN A HISTORICAL CONTEXT - EVIDENCE FROM UPLANDS TO ESTUARY

Paper number: 59-3
Program: Theme Sessions
Time: 8:25 AM – 8:45 AM

Authors

Abstract

Upland flooding and erosion during Hurricane Irene in August of 2011 left behind sedimentological recorders in a variety of depositional areas, including natural mountain lakes, upland reservoirs, and lowland floodplains. Several studies in the sub-field of paleohydrology have successfully related sedimentary event layer spacing to storm frequency, but intensity of individual events is more difficult to ascertain. Irene provided a modern and well documented extreme weather event that allows for detailed juxtaposition of causal mechanisms with resultant sedimentation. Both “natural” geomorphic processes and anthropogenic landscape changes affected surface process response to Irene-associated flooding and erosion. Here we present data from several coring locations that allow us to deconvolve some of the major factors affecting event sedimentation.

A long core from a slackwater embayment in the freshwater tidal portion of the Connecticut River reveals that Irene’s event layer is unique in many ways from historical storms recorded in the site’s sedimentary record. Notably, Irene sediment was finer grained and more enriched in unweathered glacial fines than any other event layer. In upland ponds and reservoirs, a similar signature was observed. However, denudation across upland New England was very heterogeneous, even in areas that received similar rainfall. This study highlights the sensitivity of different landscapes to yield sediment during extreme rainfall. It also provides valuable insights about interpreting floodplain event deposition.