1. What is KSA-VRF14?
Kingdom Saudi Arabia Vertical Reference Frame (KSA-VRF14) is the latest realization of the National Vertical Reference System (NVRS). The height system that is used in the KSA-VRF14 is the Helmert-Orthometric Above Mean Sea Level at the JEDDAH Tide Gauge (TG). KSA-VRF14 has been established on the base of:
- in situ observations from TG's, terrestrial national gravity and leveling networks
- satellite altimetry and GOCE data.
2. What is the primary datum benchmark of KSA-VRF14?
The primary datum benchmark (BM) of KSA-VRF14 is a Jeddah TGBM-B benchmark located in Jeddah port (approximate coordinates: Latitude 21.49981⁰, Longitude 39.16161⁰). Jeddah TGBM-B’s Helmert-Orthometric fixed height above Mean Sea Level (for epoch 2014.75) is 1.7446 m, and this value defines the height system in KSA-VRF14.
3. Who is responsible for maintaining the KSA-VRF14?
General Authority for Survey and Geospatial Information (GASGI, former GCS).
4. What are the other realizations of the National Vertical Reference System (NVRS) available in KSA?
There are three previous realizations of NVRS:
- JED69 based on the local mean sea level at the Jeddah TG on the west coast of Saudi Arabia and estimated by the Ministry of Petroleum.
- SVD71 based on the local mean sea level at the Jeddah TG on the west coast of Saudi Arabia and re-adjusted by ARAMCO company.
- SVD78 based on the local mean sea level at the Ras Tanura Tidal BM on the east coast of Saudi Arabia (i.e. in the Arabian Gulf), re-adjusted by ARAMCO company and shifted by +0.79 m from SVD71 and JED69.
5. Is it possible to transform orthometric heights from JED69 or SVD78 to KSA-VRF14?
YES!
A specially designed online tool is ready for use by you. Please, follow this link: Online Height Transformation Tool and you will be able to transform a single point (by manual input) as well as multiple points from the input file.
6. What will I need to transform my data from JED69 or SVD78 to KSA-VRF14 with Online Height Transformation Tool?
If you have only one point then you will need the following input data:
- Latitude & Longitude of your point in decimal degrees or degrees, minutes and seconds.
- Orthometric height in JED69 or SVD78.
If you will have more than one point, you can enter the above mentioned values, separated by a few spaces, into the ASCII text file (*.txt or *.dat extension) in the following order:
Latitude
| Space delimiter | Longitude | Space delimiter | Orthometric height |
| Latitude | Space delimiter | Longitude | Space delimiter | Orthometric height |
| ..... | ..... | ..... | ..... | ..... |
| Latitude | Space delimiter | Longitude | Space delimiter | Orthometric height |
7. What accuracy will I get after transformation from JED69 or SVD78 to KSA-VRF14?
Height transformation itself will be done with the accuracy of 2 - 3 cm. However, you should always keep in mind that the accuracy of the transformation result in KSA-VRF14 will always depend on the accuracy of input data in JED69 or SVD78 as well.
8. How can I use KSA-VRF14?
By using orthometric heights of KSA National Vertical Network (NVN) benchmarks as reference you will be using the KSA-VRF14 by default.
9. What is NVN?
KSA National Vertical Network (NVN) is physical realization of KSA-VRF14. It’s a network of geodetic benchmarks on the Earth’s surface with observed values of orthometric height in KSA-VRF14. NVN has been observed using precise leveling of the Second Order / Class I according to National Geodetic Survey (NGS) Standards. NVN also includes:
• National Tide Gauge Network - 12 metrological TG stations, established in 2012 and linked to KSA-NVN BMs.
• National Gravity Network - is the network of benchmarks where the absolute gravity value has been determined by absolute or relative gravimetric observations.
10. How can I get data from NVN?
If you want to get data from NVN, please, follow steps described below:
- Download National Vertical Network (NVN) map in KMZ format.
Select required benchmarks.
Request the data you need by using the email address: info@gcs.gov.sa using the information described above.
11. How can I report missing or disturbed NVN benchmarks?If you have found any missing, destroyed or disturbed benchmark, please inform us by email
info@gcs.gov.sa. We will be grateful for your feedback.