Real time quantification of relocated sediment using ADCP and OBS measurements
Type:
Presented during:
WODCON XVII: "Dredging in a Sensitive Environment" - 2004, Hamburg, Germany
Authors:
J.H. Aardoom and J.W. Mol
Abstract: Nowadays authorities demand a full control of the environment surroundings during dredge and disposal operations. In the vicinity of these operations, the amount of suspended sediment must be monitored constantly. Based on the monitoring results, one is able to intervene in case certain preset threshold values are surpassed. For this reason the survey results must be available in real time, either on screen or as an alarm signal.
In general, optical devices are used for measurements of suspended sediment concentration (SSC). However, optical devices have the disadvantage that they perform point measurements, and therefore do not provide an synoptic view of the area of interest. Using acoustic devices, suspended sediment can be measured from a distance with a high degree of spatial resolution. Unfortunate, it is not possible to quantify SSC with just acoustic devices. Several methods of a combined use of optical and acoustical techniques have been described in literature. These studies show that these techniques are complementary.
This paper presents a case study in which relocated sediment is quantified in real time using simultaneous measurements with an Acoustic Doppler Current Profiler (ADCP) and an optical backscatter (OBS) sensor. The data are acquired and processed by the operational software package VISEA-PDT, driven by real time sensor output acquired from serial ports. The software displays the processed SSC in a three-dimensional overview at the surveyor's monitor. The software uses ADCP and OBS data as primary input and additional data, including Conductivity, Temperature and Depth (CTD) for more accurate processing.
Keywords: relocation, dredged sediment, ADCP, real time, monitoring