FLOODING AND PALEOCLIMATOLOGY OF CENTRAL NEW HAMPSHIRE WETLANDS

Every watershed has its own local potential for flooding, but the scale of regional events affects multiple watersheds. By examining paleoflood records of regional events, we can determine the frequency of these floods and improve resilience to them at the local scale.

Selecting the right management style for a particular wetland is important for maintaining a functioning and sustainable environment. Increased development or unsustainable management approaches can lead to changes in local hydrology and increased erosion of the shore, enhancing sediment build up on the lake/wetland beds and causing eutrophication at an increasing rate.

Multiple sediment cores have been extracted from two flood-sensitive wetlands, Quincy Bog in Rumney, New Hampshire and McLane Bog located on Newfound Lake. I have analyzed these cores in the laboratory at Plymouth State University to determine evidence of flood deposits. This has been done by calculating bulk density and water content, organic matter (by loss on ignition), magnetic susceptibility to determine the extent of weathering/erosion of sediments, and particle size distribution, which is indicative of energy transport and water flow rates. Using Carbon-14 and Lead-210 isotopes, layers within each core have been dated and correlated to determine whether flooding events are local or regional, overlapping at both sites. Timing of apparent floods in these cores correlate very well with historic warm periods including the Medieval Warm Period and the Holocene Climate Optimum.