A DECISION-MAKING FRAMEWORK FOR SEDIMENTATION ANALYSES IN DAMMED RIVER CORRIDOR IMPOUNDMENTS

Sediment core retrieval and analysis in freshwater lakes shallower than 20 m is a fundamental tool for a wide variety of studies in lacustrine and fluvial sciences focused on investigations of historical landscape and river corridor changes, including damming. Yet, many cores are collected and analyzed without complete understanding of the local stratigraphic setting that lends to their architecture. Core interpretations themselves are used as context for models of spatially variable geomorphic change. Knowledge, tools, and techniques to understand the stratigraphic context associated with coring locations have improved and become more widely accessible in recent years. Delineation of the limits of a sediment deposit and specification of the number of measurements necessary to quantify sedimentation rates accurately are examples of problems confronting lake sedimentation analyses. The problems are particularly difficult in post-glacial settings where sedimentation rates are low and pond morphometry is complicated by features resulting from a combination of glacial and anthropogenic processes. We propose that ground-penetrating radar (GPR) allows for portable, low cost-of-mobilization shallow subsurface geophysical investigations that can provide measurements to guide selection of informative coring locations. GPR transects are easy to integrate with core results, and are useful for non-destructive, reproducible sub-aqueous geological data collection. Moreover, the method we propose for subsurface profiling of shallow, freshwater lakes in river corridors of the Northeast is far more portable and can resolve layering within and below gas- and organic-rich overburden far better than traditionally used shallow seismic reflection (SSR) profiling. We provide examples of how GPR can be a valuable decision-making tool for core extraction field campaigns important to watershed, river, and lake assessments to guide modern watershed and river management strategies.