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Sediment Quality Sampling Design for Darwin Harbour



Sediment Quality Sampling Design for Darwin Harbour


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


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




Darwin Harbour


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.


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




Sediment quality; Tidal hydrodynamics; sediment sampling; design analysis

Publisher name

Northern Territory Government

Place of publication



Report Number 44/2019


43, 74 pages : colour maps ; 30 cm

File type





Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government



Parent handle


Citation address


Page content

-28 0.001953125 0.015625000 0.125000000 5 10 20 30 40 50 60 70 80 90100 120 200 1000 Number of samples M ax im um E rr or Method cLHS Random Regular 2D Spatially balanced nD Spatially balanced Figure 23: Comparison of the maximum Error conditional on sample size and sampling method for the East Arm 1.907349e06 3.051758e05 4.882812e04 7.812500e03 5 10 20 30 40 50 60 70 80 90100 120 200 1000 Number of samples M in im um E rr or Method cLHS Random Regular 2D Spatially balanced nD Spatially balanced Figure 24: Comparison of the minimum Error conditional on sample size and sampling method for the East Arm On the basis of Figures 22, 23 and 24 we could conclude that a sample size of 100 within East Arm is a sound choice, although it is likely that as few as 50 could still potentially yield similar overall patterns. The sample size of 100 also accommodates a buffer against sample loss. Nevertheless, this entire simulation process is contingent on a number of unverifiable assumptions: 1. that the Munksgaard 2012 sediment sampling data are representative of the typical conditions and spatial patterns. 2. all Munksgaard 2012 sediment chemicals are equally useful and informative. 3. the INLA models are able to fully represent the true underlying conditions. 4. the costs and logistics of sampling are equal irrespective of location.

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