Oman National Geoid Model (ONGM):
A height modernization effort by developing a gravity network that will enable all organizations within the Sultanate of Oman to determine accurate orthometric heights is still ongoing and the current status is that, the implementing company has completed the Airborne Gravity Survey for the entire Sultanate as well as the Ground Gravity Survey covering a total of 31,339 square kilometers and Precise Leveling Survey in some parts of the Sultanate. The collected Data is now being processed for the calculation of the Sultanate Geoid Model and the Establishment of the Oman National Gravity Database.

Precise Leveling Work

Study of existing leveling was done and establish new leveling routes were created to tie in loop and hanging lines. This implies verification, replacement and creation of new benchmarks along specific routes.

It is the highest order of leveling works
Used for transferring height to benchmarks
Approx. 300 benchmarks are used
These benchmarks are then used for GPS observation to implement GPS - Geoid Fitting process

Ground Gravity Survey Work

To acquire accurate GPS-positioned ground gravity measurements at 2 km spacing over the cities and populated areas of Oman for a total of approximately 6000 gravity data points.

Airborne Gravity Survey

To cover the entire country with airborne gravity surveys at 5 km and 10 km spacing including marine area of up to 20 km from the coastline of The Sultanate of Oman.
A total of approximately 66,000 line-km including perpendicular control line with spacing of 25 km to 50 km as required.

This project is completed and a fitted Geoid Model is available for Oman now as shown above. A final Acceptance Test (FAT) is carried out by selecting GPS on Benchmarks in the North, Central and Southern part of Oman and it is observed that the fitted geoid satisfies the needs of the users who will be using GNNS levelling for accurate orthometric height determination at the centimeter level.