Territory Stories

Sediment Quality Sampling Design for Darwin Harbour

Details:

Title

Sediment Quality Sampling Design for Darwin Harbour

Creator

Brinkman, Richard; Logan, Murray; Northern Territory. Department of Environment and Natural Resources; Australian Institute of Marine Science

Collection

E-Publications; E-Books; PublicationNT; Report Number 44/2019

Date

2020-01-06

Location

Darwin Harbour

Description

In the context of increasing development and associated pressures, this project aims to inform the development of a first systematic, long-term, sediment monitoring program for Darwin Harbour which takes into consideration the physicochemical nature of Darwin Harbour sediment and the oceanographic processes which will influence the movement of contaminated sediment in the Harbour. The rationale for the program is that seabed and estuarine sediments are both an extensive habitat and the ultimate repository for many contaminants that enter waterways. In addition, monitoring of contaminants in sediment may facilitate the identification of increasing contaminant loads in the Harbour which may not be detected by water monitoring programs due to the high flushing rate within Darwin Harbour and infrequent water sample collection.

Notes

Made available by via Publications (Legal Deposit) Act 2004 (NT).

Table of contents

1. Executive summary -- 2. Introduction -- 3. Methods -- 3.1 Overview of methodology -- 3.2 Tidal Hydrodynamics -- 3.3 Wave Dynamics -- 3.4 Sediment Modelling -- 3.5 Sediment sampling design analysis -- 4. Results -- 4.1 Tidal and wave driven hydrodynamic processes -- 4.2 Sediment transport modelling -- 4.3 Sediment characteristics from previous sampling programs -- 4.4 Sediment sampling design analysis -- 4.4.1 Existing chemical sediment data, Outer Harbour sediment monitoring data, and designated sampling sites -- 4.4.2 Hydrodynamic modelling layers -- 4.4.3 Exclusion zone masks -- 4.5 Spatial Model fitting -- 4.5.1 Background on statistical techniques for designing sediment sampling program -- 4.5.2 Results from statistically derived sampling design - East Arm -- 4.5.3 Results from statistically derived sampling design - Outer Harbour -- 4.5.4 Representation of sampling sites mapped with hydrodynamic and sediment modelling parameters -- 4.6 Harbour Sediment Zonation, and conceptual representation: -- 5 Conclusions -- 6 References -- 7 Appendix 1

Language

English

Subject

Sediment quality; Tidal hydrodynamics; sediment sampling; design analysis

Publisher name

Northern Territory Government

Place of publication

Palmerston

Series

Report Number 44/2019

Format

43, 74 pages : colour maps ; 30 cm

File type

application/pdf

ISBN

9781743502303

Use

Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government

License

https://creativecommons.org/licenses/by/4.0/

Parent handle

https://hdl.handle.net/10070/755961

Citation address

https://hdl.handle.net/10070/765802

Page content

3 Figure 17 Two dimensional spatially balanced sampling configuration for the East Arm (100 samples) .............................................................................................................................................................. 30 Figure 18 Comparison of the mean Error conditional on sample size and sampling method for the Outer Harbour ....................................................................................................................................... 31 Figure 19 Two dimensional spatially balanced sampling configuration for the Outer Harbour (100 samples) ................................................................................................................................................ 32 Figure 20 50th percentile of tidally generated seabed shear stress (N/m2). Contour shows 0.1 N/m2 (approx. threshold for erosion of fine sediment). Coloured circles indicate locations of statistically derived sampling sites. ......................................................................................................................... 33 Figure 21 Composite dataset of maximum Wave induced Orbital Velocity (m/s) generated from sustained winds of 10m/s (36km/hr) from dominant wind directions. Contour shows 0.1, 0.2, 0.3 m/s. Coloured circles indicate locations of statistically derived sampling sites. ................................. 34 Figure 22 Zonation of the Inner Harbour into areas of nett Deposition and nett Erosion. Derived from cohesive fine sediment transport model, and only applicable to the Inner Harbour where fine sediment is the dominant sediment class. Coloured circles indicate locations of statistically derived sampling sites. ....................................................................................................................................... 35 Figure 23 Conceptual diagram of fine sediment transport pathways within Darwin Harbour. .......... 38 Figure 24 Conceptual diagram of sediment zonation within Darwin Harbour. ................................... 39 Figure 25 Sand transport pathways in Darwin Harbour. From Tonyes (2018) - Sand dynamics in Darwin Harbour: a tool for coastal management. A thesis submitted for the degree of Doctor of Philosophy, CDU (currently unpublished) ............................................................................................. 40


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