Baseline Monitoring for Dredging Planning and Management - Data Review and Analysis.

Redland City Council (RCC) Marine Infrastructure Asset Management Branch commissioned KBR to design and implement a marine baseline water quality monitoring program. The monitoring program includes telemetry enabled water quality monitoring buoys at three locations in Southern Moreton Bay, Queensland. The focus of this baseline monitoring is to obtain an improved understanding of natural variability of turbidity in shallow near shore settings. The monitoring buoys measure turbidity at 15 minute intervals and the data is logged and streamed in 'real time' to a web site. This monitoring has been underway for four years and data has been recovered and reviewed for all locations. Each of the monitoring locations is near small vessel navigation channels which require regular maintenance dredging. Turbidity and suspended solids concentration are important water quality parameters for planning and managing dredging campaigns as they are linked to the key dredging and sediment disposal impact mechanisms. Publicly available baseline water quality data for Moreton Bay is from 'grab' samples at low frequency from deeper offshore settings and does not capture the processes which influence turbidity in shallow near shore waters. The monitoring program discussed in this paper addresses this gap and is collected at a frequency which is sufficient to capture diurnal and tidal cycles. This paper discusses the design of the monitoring program, some of the challenges to preserving data integrity, and presents some example data sets. It also discusses what data coverage is practically achievable from a simple small scale monitoring program with limited budget. The results of data analysis to date show that natural site specific processes cause episodes of elevated turbidity. Because of the short duration of these turbidity episodes they are not evident in 'grab' sample data or summary statistics and can only be seen by examining continuous time series data. [ABSTRACT FROM AUTHOR]