This index enables you to identify the georeferenced TIFF images of sounding sheets held by LINZ throughout the SW Pacific region. Some of these sounding sheets date back to the 1950s. The polygons comprising the index show the extent of each original hard copy sheet - not just the soundings shown on the sheet. The attributes attached to each polygon will enable you to view, amongst other attributes, the date and scale of the bathymetric data shown on the sounding sheet. Please refer to the LINZ Bathymetric Index Data Dictionary for further information about the attributes of this dataset. The georeferenced TIFF images are not downloadable from the LINZ Data Service Requests for sounding sheets should be sent to email@example.com with “Hydro Bathy Data” in the subject line. Requests must, as a minimum, specify the id, chart_no and serial_no as shown in the attributes attached to each polygon representing the sounding sheets of interest. The provision of this bathymetric data may be subject to some delay as LINZ confirms with the data owner that they are happy for their data to be released. The owner may attach conditions to the release of their data.
National hydrographic offices are responsible for undertaking or commissioning hydrographic surveys to facilitate the production of nautical charts to enable nations to meet their obligations under the International Convention for the Safety of Life at Sea. Traditionally the bathymetric data collected during hydrographic surveys was rendered only as sounding sheets in hard copy form, often as A1 (or larger) sheets. More recently the bathymetric datasets have often been rendered as both sounding sheets and as digital data files, with the provision of sounding sheets diminishing over time. The sounding sheets have been scanned and georeferenced to make them available as TIFF images. This index has been derived from the extents of the georeferenced images and information held in LINZ’s hydrographic information database. LINZ’s bathymetric data is usually based on minimum seabed depth (shoal-biased) values. This means if two soundings are close together we choose the lesser (shallower) one as safety is our primary concern.