# Strategies and methods that Datums and Coordinate Systems use to account for movement of the earth's surface

Are there `datums` and `coordinate systems` that address the issue of shifting coordinates through time? If so, what are some of the strategies and methods that the `datums` and `coordinate systems` use to address the issue?

To provide some context:

Several Earth processes, plate tectonics and isostatic rebound, affect where a `(x, y, z)` location is (or perhaps better, is calculated to be) in a time step `t1` in comparison to a different time step `t2`. In some areas of the world, such as California, USA, this movement can be in the magnitude of centimeters per year. For some GIS analysis the shift in `(x, y, z)` locations could have a serious effect on the results, for example examining sediment flux that rely on comparing raster cells and/or coordinates across different time steps often spanning several years or decades.

• How are you defining your x,y,z ? Many coordinate systems are fixed with respect to what they apply to (see ga.gov.au/scientific-topics/positioning-navigation/geodesy/… for an Australian example, which is moving 7cm/year). – BradHards Oct 23 '15 at 6:22
• @BradHards Thank you for the link. This is the type of information I am looking for :-) This is more of an in general question and examples are welcome, I have edited the question to reflect that. It is difficult for me to answer your question. But in the example given of tracking sediment flux, I think the (x, y, z) can be defined in two ways (perhaps more) one which (x, y, z) tracks a location on the surface of a moving plate, the other (x, y, z) is a fixed location that depending on the time step could be a different location on the moving plate. – GeoSharp Oct 23 '15 at 6:52
• There are a couple of answers here which discuss NAD83(CSRS), Proj.4 and Natural Resources Canada's TRX tool, which transforms coordinates w/r/t tectonic and isostatic movement. – Rob Skelly Oct 26 '15 at 17:06
• You'll likely also want to look at the NGS's HTDP software and connected papers. – mkennedy Oct 27 '15 at 21:28