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Kaipara Harbour Sedimentation Report

Land use changes and modification of coastlines following European settlement from the mid 1800s have substantially increased soil erosion and sediment accumulation rates in New Zealand estuaries. 

In response to growing concern about sedimentation rates in the Kaipara Harbour and following an earlier recommendation in a review of sediment data, Northland Regional Council partnered with Auckland Council and NIWA to investigate historical sediment accumulation in the Kaipara Harbour.   The project involved the collection and analysis of sediment cores, to reconstruct the sedimentation history of the harbour over the last century.

Due to the size of the document it has been broken into the following sections

Sections 1-3

1 Executive summary

2 Background
2.1 Study objectives
2.2 Estuary sedimentation
2.3 Study area

3 Methods
3.1 Sediment-core sampling
3.2 Sediment bulk density
3.3 X-radiographs
3.4 Particle size
3.5 Radioisotope dating
3.6 Recent changes in the spatial extent of vegetated intertidal habitats

Section 4

4 Results
4.1 Sediment core profiles
4.2 Recent changes in vegetated intertidal habitats

Sections 5-8

5 Synthesis
5.1 Recent sedimentation in the Kaipara Harbour
5.2 Recent changes in intertidal vegetated habitats

6 Acknowledgements

7 References

8 Appendices
8.1 Location of sampled core sites
8.2 Appendix: Dating of estuarine sediments