Geomorphological Response to Hydraulic Processes: A Study of Erosion in the Connecticut College Arboretum

Abstract:
The role of hydraulic processes in the differential erosion of two parallel channels forms in loosely consolidated sediment was investigated in the Connecticut College Arboretum; New London, CT. Hydraulic flow preferentially through one of two parallel channels results in the development of a meandering channel with pool-riffle bed forms and sculpted channel wall characteristics. The other channel lacks significant hydraulic input resulting in an almost featureless channel bed with loosely consolidated or undercut channel walls. Groundwater levels around channels were monitored in wells. Substrate characteristics were described using sediment composition analyses on samples from the well boreholes, and resistance to deformation readings on channel walls. A relative input of overland flow into the channels was found using stream gages. Erosion of the channel walls was tracked seasonally using topographic measurement techniques. Sediment compositions are similar, while the channel with sculpted wall forms has higher overall resistance to deformation. Groundwater levels were similar in each channel substrate. Overland flow was significantly higher into the channel with pool-riffle bed forms and sculpted walls. The amount of hydraulic flow therefore was found to be the most important factor for the development of channel characteristics.