Sediment deposition data (NESP TWQ 2.1.9, AIMS)

This dataset consists of 1 excel data files (.xlsx format) that contains the results from the in situ deployment of instruments in Cleveland Bay to measure sediment deposition from a trailer suction hopper dredge working in Platypus channel. The aim of the study was to measure sediment deposition rates caused by a working Trailer Suction Hopper dredge in Platypus channel in Cleveland Bay.

Methods:
Two deposition sensors were deployed on the seabed 100 m (-19.226083° 146.843500°) away from the edge of the Platypus channel in Cleveland Bay near marker beacon P11 at a depth of 5–8 m. Single deposition sensors were also placed on a transect line running at right angles from the shipping channel at distance of 200 m (19.225639° 146.842889°), 400 m (-19.224528° 146.841111), and 800 m (-19.222806° 146.837889°). The deposition sensors were calibrated according to methods described in Ridd et al. (2001), Thomas et al. (2003), Whinney et al. (2017).

The deposition sensor uses infrared optical backscatters techniques to estimate the mass of sediment per unit area that deposits on the sensor surface every 10– 20 minutes. After 1 h the surface is wiped clean and the process repeated.

Additional instruments were deployed alongside the sensors including a nephelometer measuring turbidity by means of optical backscatter, a pressure sensor for estimating wave activity, and a tilt current meter for estimating current speed. For instrument descriptions and calibration details see Macdonald et al. (2013), Marchant et al. (2014), Whinney et al. (2017).

Limitation of the data:
All data went through a quality assurance process involving an algorithm to remove occasional data spikes. This algorithm compares each reading to the average of the readings directly before and after it, and if the reading is greater than twice the average it is replaced by the average. Fouling of sensors was examined by looking for drift in values over the deployment period and from observations of the condition of the sensors at the time of retrieval. Data that have been affected by fouling were removed.

Format:
This data is in a single Excel file

Data Dictionary:

Site 1A - 100m from Channel
Site 1B - 100m from Channel
Site 2 – 200 m from Channel
Site 3 – 400 m from Channel
Site 4 – 800 m from Channel

Columns B – F : hourly sensor readings of sediment deposition as mg/cm2/day

per 10 minute intervals:
Column I: 2 – NTU (Nephelometric turbidity unit) at Site 2 – 200 m from Channel
Column J: m (metres, water depth) at Site 4 - 800 m from the Channel
Column K: m/s (metres per second) current sensor readings at Site 4 - 800 m from the Channel

Graphs of the data can be found in the Report in figures 16 B, 16 C, and 16 D: Ross Jones, Rebecca Fisher, David Francis, Wojciech Klonowski, Heidi Luter, Andrew Negri, Mari-Carmen Pineda, Gerard Ricardo, Matt Slivkoff James Whinney. Risk Assessing Dredging activities. Report to the National Environmental Science Program. Reef and Rainforest Research Centre Limited, Cairns (74 pp).

References:
Macdonald R, Ridd P, Whinney J, Larcombe P, Neil D (2013) Towards environmental management of water turbidity within open coastal waters of the Great Barrier Reef. Mar Pollut Bull 74:82-94

Marchant R, Stevens T, Choukroun S, Coombes G, Santarossa M, Whinney J, Ridd P (2014) A Buoyant Tethered Sphere for Marine Current Estimation. IEEE Journal of Oceanic Engineering 39:2-9

Ridd P, Day G, Thomas S, Harradence J, Fox D, Bunt J, Renagi O, Jago C (2001) Measurement of Sediment Deposition Rates using an Optical Backscatter Sensor. Estuar Coast Shelf Sci 52:155-163

Thomas S, Ridd PV, Day G (2003) Turbidity regimes over fringing coral reefs near a mining site at Lihir Island, Papua New Guinea. Mar Pollut Bull 46:1006-1014

Whinney J, Jones R, Duckworth A, Ridd P (2017) Continuous in situ monitoring of sediment deposition in shallow benthic environments. Coral Reefs 36:521–533

Ross Jones, Rebecca Fisher, David Francis, Wojciech Klonowski, Heidi Luter, Andrew Negri, Mari-Carmen Pineda, Gerard Ricardo, Matt Slivkoff James Whinney. Risk Assessing Dredging activities. Report to the National Environmental Science Program. Reef and Rainforest Research Centre Limited, Cairns (74 pp).

Data Location:

This dataset is filed in the eAtlas enduring data repository at: data\nesp2\2.1.9-dredging-marine-response