sediment transport; mountain stream; torrent; bedload transport measurement; geophone sensor; river engineering; fluvial geomorphology
Turowski Jens M., Hilton Robert G., Sparkes Robert (2016), Decadal carbon discharge by a mountain stream is dominated by coarse organic matter, in Geology
, 44(1), 27-30.
Rickenmann D., Turowski J.M., Fritschi B., Wyss C., Laronne J., Barzilai R., Reid I., Kreisler A., Aigner J., Seitz H., Habersack H. (2014), Bedload transport measurements with impact plate geophones: Comparison of sensor calibration in different gravel-bed streams, in Earth Surface Processes and Landforms
, 39, 928-942.
Turowski Jens M., Badoux Alexandre, Leuzinger James, Heggline Ramon (2013), Large floods, alluvial overprint, and bedrock erosion, in Earth Surface Processes and Landforms
, 38, 947-958.
Turowski J. M., Badoux A., Bunte K., Rickli C., Federspiel N., Jochner M. (2013), The mass distribution of coarse particulate organic matter exported from an Alpine headwater stream, in Earth Surface Dynamics
, 1(1), 1-11.
Rickenmann D, Turowski JM, Fritschi B, Klaiber A, Ludwig A (2012), Bedload transport measurements at the Erlenbach stream with geophones and automated basket samplers, in Earth Surface Processes and Landforms
, 37(9), 1000-1011.
Nitsche M, Rickenmann D, Turowski JM, Badoux A, Kirchner JW (2011), Evaluation of bedload transport predictions using flow resistance equations to account for macro-roughness in steep mountain streams, in WATER RESOURCES RESEARCH
, 47, W08513.
Turowski Jens Martin, Rickenmann Dieter (2011), Measuring the Statistics of Bed-Load Transport Using Indirect Sensors, in JOURNAL OF HYDRAULIC ENGINEERING-ASCE
, 137(1), 116-121.
Turowski Jens Martin, Badoux Alexandre, Rickenmann Dieter (2011), Start and end of bedload transport in gravel-bed streams, in GEOPHYSICAL RESEARCH LETTERS
, 38, L04401.
Accurate prediction of bedload transport is important for hazard assessment and in engineering applications. Furthermore, a wide range of scientific disciplines such as geomorphology or sedimentology rely on such predictions for modeling work. Despite more than a hundred years of active research, knowledge of bedload transport processes is still limited, and none of the multitude of published models are able to describe observations in all conditions occuring in nature. This is especially true for alpine torrents, i.e. high-gradient mountain streams. Bedload transport is typically very variable for given streamflow conditions. Continuous and reliable measurements of bedload transport is difficult and challenging, but important to advance our understanding of sediment transport in mountain streams.The main purpose of this proposed research project is to advance the understanding of bedload transport processes through detailed field observations. In addition to direct sediment transport observations using several methods, we intend to improve and further develop an existing indirect acoustic method using geophones for measuring bedload transport in gravel bed streams and torrents. Detailed laboratory investigation and comparison with field observations will allow more accurate and detailed interpretation of the data it records. The sensors function at times and under conditions when direct observations are not possible, for example during high stage floods. We expect that the present research proposal will allow more accurate determination of bedload transport rates from the acoustic data and to extract additional information about the the transported material, such as the median grain size. Together with high resolution field measurements at low discharges and observations of tracer motion during single transport events, this will provide a comprehensive dataset to study transport processes in mountain streams. Specifically, this will be done within two main tasks, and the combination of the obtained results with additional geophone and bedload transport measurements from complementary field sites.In Task A we will exploit the monitoring facilities in the experimental hydrologic catchment of the Erlenbach, canton Schwyz, Switzerland, which is maintained by the Swiss Federal Research Institute WSL. These facilities will be upgraded in autumn 2008. Sediment will be automatically sampled during transport events to provide detailed information on transport rates and grain size distribution over short time scales. Geophone measurements at high temporal resolution will be made concurrently to allow analysis of the effect of changing grain size distribution and flow properties on the geophone signal response and to provide continuous data at high discharges. The measurements will be complemented by observations from a tracer study using a passive radio system to obtain data on initiation of bedload transport and on travel distances. This will improve the site-specific calibration relation for an indirect sediment monitoring system, which is based on the acoustic signals recorded by geophones deployed in the stream.In Task B we will investigate the geophone system in detail in a series of laboratory flume experiments. A particular focus will lie on understanding the origins of fluctuations in the measurements for similar boundary conditions, on characterizing in detail the sensor response to changing conditions of the flow and of the sediment properties, and on exploring the possibility of extracting information on grain size in addition to the total load from the signal. Results will be compared to field data obtained in the Erlenbach for validation and to aid with some aspects of Task A.In an overarching analysis of the results from Tasks A and B in Task C we will improve the site-specific calibration relationships for the geophone system at the Erlenbach. Bedload transport measurements with the geophone system will also be calibrated for the field sites of the Eshtemoa stream in Israel, and the Drau and Pitzbach rivers in Austria. An inter-comparison of the field data with the results from the laboratory study will provide further insight into the functioning of the geophone measuring system in different environments. Particular emphasis will be directed to the extent to which the interpretation of geophone measurements can be generalized to field sites other than the ones studied within this project. The new insights will thereafter be utilized to study bedload transport processes in a set of 12 field sites in mountain streams for which geophone measurements are or will be available. In particular, the data will be analysed to obtain information on the statistics of transport rates.