Estuarine sediment monitoring

Sediment characteristics for an extensive number of sites in Tairua and Whangapoua harbours. The sites have been established to monitor long-term trends in sediment characteristics in these estuaries. Purpose: State of the Environment monitoring

Approximately 120 samples from Tairua Harbour and approximately 140 samples from Whangapoua Harbour. Samples have been sieved and sediment size distributions (for sand-sized fraction) are available for all sites, together with a range of sediment size parameters (mean grain size, sorting, principle mode, skewness, etc.). The analyses exclude the coarse shell content of the samples as the monitoring is focusing on the terrigenous component of the sediment. Percentage mud is also available. All samples have been archived – including representative samples of the sediments as collected, and the washed and dried sub-samples used for analysis. Good site photographs are also available for all sites.

Tairua and Whangapoua Harbours

Tairua Harbour - NZMS 262-3 462764 Whangapoua Harbour NZMS 262-3 493746 Scale 1:250,000

Data collected December 1991 – January 1992.

Collection of sediment samples from survey transects, with sample site distances marked by EDM from transect benchmarks. Sub-tidal samples were collected by SCUBA. Labelled photographs were taken at each site. Transect benchmarks are being surveyed, as resources permit, to establish sample site co-ordinates within 5m and levels within 0.1m. Sediment samples washed and, after removal of coarse shell fraction, sieved. Sediment size parameters were then calculated. Maps of sediment parameters are being produced for each of the estuaries as time and resources permit. Tairua Harbour is presently available. Frequency of collection: One-off data collection. No specific date set for re-sampling.

Not reported Gaps in collection: Not reported Data quality: Site positions accurate to within 5m. Weight-percent sediment size data accurate to 3% for terrigenous fraction. Attribute accuracy: N/A Completeness: Sample sites provide extensive coverage of the main areas of both harbours – but limited data in side arms of both harbours and the upper estuary-riverine reaches of Tairua Harbour.

digital, printed graphs and tables, half-tone showing sample sites, finder diagrams, transect benchmarks, sediment parameter maps available for Tairua Harbour. Digital Format: MS Excel and GIS

Established to monitor the effect of catchment land-uses on estuarine sediment properties. Existing data set also has a variety of other coastal management uses and assists in understanding sediment dynamics of the harbour.

Unrestricted. Hard copy maps available to view at Environment Waikato. Sensitivity/Confidentiality: None

Ongoing analysis as resources permit.

Additional comments: As resources permit, the data will be entered into GIS databases to produce maps with various sediment size parameters for both harbours. This work has been completed for Tairua and sediment parameter maps for this harbour are now available. Related information: Beach profiles Regional Estuaries Monitoring Programme