APPLICATION OF ADCPS FOR LONG-TERM SEDIMENT TRANSPORT MONITORING IN ARCTIC ENVIRONMENTS - EXAMPLES FROM THE LAPTEV SEA

摘要

For offshore constructions the knowledge on sediment transport dynamics is essential and the quantification of suspended particulate matter (SPM) is of major importance. The Laptev Sea shelf is one of the largest Siberian shelf seas and ice-covered for about nine months a year. In order to use indirect measuring devices for the quantification of SPM concentration on the Laptev Sea shelf, optical (turbidity meter) and acoustic (ADCP; Acoustic Doppler Current Profiler) backscatter sensors were compared to assess their potential for the investigation of SPM dynamics in an arctic environment. To estimate SPM concentrations from optical backscatter signals, these were converted using the linear relation between the backscatter signals and SPM concentrations derived from water samples. Applying the theoretical interaction of sound in the water with SPM the acoustic backscatter signals were transformed adapting a previously established approach. SPM concentrations estimated from the backscattered signals of both sensors showed a close similarity to SPM concentrations obtained from filtered water samples. While the ADCP offers distinct advantages over the turbidity meter in that it allows measurement of the complete concentration profile, bottom location, and currents, co-deployment of both sensors are recommended for improved SPM measurements.