206 



Increased attention to neo-tectonic contributions to tide-gage results 

 might prove useful. Basic research is required- -not just some "weighted 

 averaging," as implied in Section 2.4.1. 



New tide gages are required, particularly in the southern hemisphere. 

 However, simultaneous attempts to identify and separate land motions from 

 sea level motions are needed. 



We need to use any historical records available to identify the full 

 spectrum of sea level change, so that we can interpret better future sea 

 level measurements. The redness of the spectrum (e.g., Sturges, 1987) 

 argues for adequate long-term measurements. 



Modeling must be accomplished where possible. We need improved 

 statistical models to isolate and predict "noise," and dynamic modeling for 

 ice sheet melting/steric expansion to help improve predictions of sea level 

 rise. 



SECT. 3. COMPACTION EFFECTS 



With reference to measuring compaction (Sect. 3.2), tectonic land 

 level changes and compaction can occur at the same location, so 

 interpretation of compaction data must be done carefully and not be taken 

 to represent the sum of all land level changes . 



The discussion of Mississippi River Delta subsidence (Sect. 3.5) is 

 not well balanced. 



Bangkok is another excellent example of land subsidence problems. 

 Bangkok is approximately 1 m above sea level; parts are sinking at a rate 

 of 10 cm/yr. 



It is not evident that installation of compaction gages is the best 

 use of money. Compaction recorders measure only one element of land level 

 change . 



Use VLBI and DGPS for surveying. 



SECT. 4. TIDAL RANGE EFFECTS 



This section addresses more than tidal range effects . Change the 

 title? 



The utility of frictionless estimates is not clear. It is better to 

 use frictional models (even if linearized friction) . 



