Abstract
Knowledge of Suspended Sediments Dynamics (SSD) across spatial scales is relevant for several fields of hydrology, such as eco-hydrological processes, the operation of hydrotechnical facilities and research on varved lake sediments as geoarchives. Understanding the connectivity of sediment flux between source areas in a catchment and sink areas in lakes or reservoirs is of primary importance to these fields. Lacustrine sediments may serve as a valuable expansion of instrumental hydrological records for flood frequencies and magnitudes, but depositional processes and detrital layer formation in lakes are not yet fully understood. This study presents a novel buoy system designed to continuously measure suspended sediment concentration and relevant boundary conditions at a high spatial and temporal resolution in surface water bodies. The buoy sensors continuously record turbidity as an indirect measure of suspended sediment concentrations, water temperature and electrical conductivity at up to nine different water depths. Acoustic Doppler current meters and profilers measure current velocities along a vertical profile from the water surface to the lake bottom. Meteorological sensors capture the atmospheric boundary conditions as main drivers of lake dynamics. It is the high spatial resolution of multi-point turbidity measurements, the dual-sensor velocity measurements and the temporally synchronous recording of all sensors along the water column that sets the system apart from existing buoy systems. Buoy data collected during a 4-month field campaign in Lake Mondsee demonstrate the potential and effectiveness of the system in monitoring suspended sediment dynamics. Observations were related to stratification and mixing processes in the lake and increased turbidity close to a catchment outlet during flood events. The rugged buoy design assures continuous operation in terms of stability, energy management and sensor logging throughout the study period. We conclude that the buoy is a suitable tool for continuous monitoring of suspended sediment concentrations and general dynamics in fresh water bodies.
Highlights
Understanding suspended sediment dynamics (SSD) has been an important topic in both applied and process research for several decades
Mean air temperature and relative humidity for the study period were 12.4 °C and 86.4%, respectively. These data are similar to a meteorological gauge operated by the Central Institute for Meteorology and Geodynamics of Austria (ZAMG) in the town of Mondsee at a distance of 3 km from the buoy
We present the design of a novel buoy system to monitor suspended sediment concentrations and related limno-physical and meteorological variables at high spatial and temporal resolution in lakes or reservoirs
Summary
Understanding suspended sediment dynamics (SSD) has been an important topic in both applied and process research for several decades. From different perspectives such as hydrology (e.g., [1]), hydraulic engineering (e.g., [2]) and sedimentology (e.g., [3]), scientists have investigated SSD in catchments and in the reservoirs, lakes and estuaries into which the watersheds drain. Many recent hydrological studies have focused on upland erosion, the resulting reservoir siltation and reduction of reservoir capacity [5,6]. Reservoir siltation can cause a serious reduction in water availability for a given region. Viseras et al [7] showed that the storage capacity of a reservoir in Spain decreased by around 80%
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