Field instrumentation for high-resolution parallel monitoring of bedrock erosion and bedload transport

摘要

River incision is fundamental in shaping the Earth's surface. In mountainous regions with steep river beds, fluvial bedrock erosion by bedload transport is an important mechanism forming channels. However, there are only a few complete field datasets that can be used to improve process understanding and evaluate erosion models, especially at the process scale. To provide a simultaneous dataset of hydraulics, bedload transport and bedrock erosion at high temporal and spatial resolution, a new measuring device has been installed in the Erlenbach, a gauged stream in the Swiss Pre-Alps. In this stream, bedload transport rates can be calculated from surveying deposits and from geophone plate sensors and bedload transport samples can be taken directly by an automated moving basket system. To measure bedrock erosion rates simultaneously, two natural stone slabs were mounted flush with the channel bed in a steel frame hosting various measurement devices. Force sensors below the slabs record normal stress and shear stress. At-a-point erosion rates on the slab surfaces are continuously measured at sub-millimetre precision at three locations on each slab. In addition, the slab topography is monitored following erosive flood events. In this article (i) the erosion scale' device is described, (ii) data resolution and data quality is assessed by means of tests and event data, and (iii) the first transport event is discussed. The erosion scales are confirmed to provide data at high spatio-temporal resolution for process analysis. The preliminary data show evidence for the tools effect in bedrock erosion. The bedrock slabs can be exchanged to obtain measurements for catchments with different lithologies for comparison. Copyright (c) 2014 John Wiley & Sons, Ltd.