Variation in sediment properties at the interface between fresh and estuarine water, Whangapoua Harbour

This thesis aims to trial techniques for measuring particle dynamics of flocs, characterise sediments around the fresh-estuarine water interface in Whangapoua Estuary. Purpose: To understand sedimentary processes within estuaries.

temporal changes to suspended sediment properties, sediment characteristics (organic content, particle size distributions and mineralogy), water column characteristics (back-scatter, current, pH, depth, conductivity, temperature, flow, barometric pressure, chloride and turbidity).

Stream mouths around Whangapoua Harbour.

2002-2003

Measuring settling properties of suspended estuarine muds and silts - Surfical cores collected in transects along all of the major streams that enter into the estuary providing a spatially comprehensive, yet time integrated, picture of sedimentation. A detailed experiment to measure temporal changes to suspended sediment properties (including settling properties and particulate composition of in situ flocs) at one location trialled over a tidal cycle. A video analysis technique to measure floc characteristics involves a combination of a high resolution video camera and a variation on the conventional settling trap. Surfical sediments – Sediments from the top 10-20 cm of the bed collected using push-cores along transects at the mouths of at least two contrasting streams (forested and unforested catchments). These ashed for organic content, particle size distributions (settling column and/or Malvern particle size analyser), and mineralogy. Suspended sediments during baseline conditions and flood events – If the video settling box trials prove successful, they will be deployed concurrently at two contrasting streams (including Optical Backscatter sensor, FSI acoustic current meter, water sampler and water traps). Each site will be monitored for one entire tidal cycle, with the instrument being moved between sites during low tide. The main sampling will occur during normal spring weather conditions; with additional sampling should a flood even occur before the end of July 2003. pH, depth, conductivity, temperature, flow, barometric pressure, chloride and turbidity readings will also be taken at surfical sediment sampling sites.

Hard copy thesis. Appendices 1-4 on CD-ROM in pocket. Digital Format: Appendices 1-4 on CD-ROM in pocket.

Master of Science Thesis, University of Waikato

Freely available in University of Waikato Library. Sensitivity/Confidentiality: No confidentiality.

Study completed.