GPS isn’t good technique for geodetic monitoring of structures, like dams or bridges due GPS low accuracy, shadow zones or dead areas in the satellite observation of structures.

I don't prefer to use such technology for this aim unless we improve the GPS accuracy.

Please check the attached files.

Thank you very much, Prof. Raed Ahmad!

Dear Prof. Raed Ahmad,

Do you have any experiences in using GPS for monitoring?

Is there any correction methods that you applied to improve the GPS accuracy?

Thank you in advances.

For monitoring dams with GPS, a most important effect to modelise correctly for a high accuracy is the tropospheric effects,  as the stations are very generally  near and the altitude difference important.

Dear Dr. Salem Kahlouche,

How do you correct the GPS results due to tropospheric effects when you monitor dams?

Thanks!

Dear Kien Nguyen, We don't use standard tropospheric models only, but we introduce the meteological measurements (Temperature, Pression, Humidity) in the processing, and the results will be better, mainly when the altitude difference between stations are important.

Dear Salem Kahlouche,

Which model do you use? I found that there are some models to correct tropospheric delays, such as Saastamoinen model. 

What are the advantages of your model compare with others?

Thanks!

The main models are constructed from the Hopfield Theory and experimentation done before 1969. The majority of the models respects the spécifications of the Hopfield conclusions

Dear Dr, Salem Kahlouche,

The height difference between the reference and monitoring stations cause the tropospheric delays in the results of GPS monitoring. 

When we apply Hopfield model to correct, the results seem to be remaining the scatters.

What should we do to reduce those scatters?

Do you apply error correction to reduce Ionospheric delays?

Thanks!