Direct Push-Sensing in Wetlands

Abstract:

Trenching techniques for the characterization of floodplain and wetland environments are challenging due to the impact of groundwater inflow and highly unstable trench edges. Alternatively, classical driving core techniques often correspond with the contraction of organic layers and bias in height accuracies. We will present direct push-sensing techniques for minimal‐invasive investigation of zones affected by a high groundwater table, especially when high‐resolution parameterization of buried (geo)archaeological structures is required. We applied electrical conductivity logging and measurement of colorimetric proxies in unconsolidated sediments. The tools provide multi‐proxy information about layer structure, texture, and organic parameters. The high sensing speed allows recording a large data set with high vertical and lateral resolution. In this study we exemplary provide results of a buried canal structure within a valley in SW Germany. The canal is part of Charlemagne’s summit canal (Fossa Carolina), an Early Medieval hydro‐engineering project bridging the Central European Watershed.

We compare direct push-sensing data with driving core samples and discuss prediction options of parameter transfer. In this context, we use in situ‐obtained colorimetric data and electrical conductivity as proxies for (geo)archaeological site characterization. We model organic fills of the canal by direct push-logs and robust sediment data. Given the cost and time effectiveness of such tools, (geo)archaeological site information of high‐depth accuracy was grown rapidly, compared to less densely performed drillings that require an additional high effort in laboratory analyses.