Development of a New Geodetic Datum and Map Grid for the Kingdom Of Tonga

Abstract

Development of a New Geodetic Datum and Map Grid for the Kingdom Of Tonga

Francis Latu
Principal Surveyor - Geodetic
Ministry of Lands, Survey and Natural Resources, Tonga
francis@lands.gov.to

Tevita Malolo
Secretary & Surveyor General
Ministry of Lands, Survey and Natural Resources, Tonga
malolo@lands.gov.to

Malcolm Archbold
General Manager - Geospatial
BECA International Consultations Ltd, New Zealand
marchbold@beca.co.nz

Graeme Smith
Licensed Cadastral Surveyor
BECA International Consultations Ltd, New Zealand
gsmith@beca.co.nz

Abstract :
There has been clear evidence in recent years that the Kingdom of Tonga’s current Geodetic Datum and Map Grid is inadequate for some current and emerging applications.

The current geodetic control network has served the cadastral system of Tonga well but it cannot now meet the requirements of new survey technologies such as Global Positioning System (GPS) or unified high accuracy Geographical Information System (GIS) applications over large areas and higher accuracy requirements, which will require the need to account for earth movements.

Under the Cyclone and Emergency Recovery and Management Project (CERMP), a new official geodetic datum for Tonga has been developed to meet the requirements of spatial referencing for all of the country’s land information needs including, but not exclusive to, mapping and cadastral systems. This Datum will be known as Tonga Geodetic Datum 2005 (TGD2005) and based on the International Reference System (ITRS2000) and that the ellipsoid associated with this datum, be the Geodetic Reference System 1980 (GRS80) ellipsoid. The new datum will be defined at 1st January 2005 through a set of 1st Order GPS sites distributed throughout the nation.

A revised Tonga Grid has been defined and the name is Tonga Map Grid (TMG).

The description of the TGD2005 and TMG, its design and implementation will be presented.