texture of the bottom sediments, among other variables. Therefore, it is 

 appropriate to require project-specific water-level gauges to be accurate to 

 ± 0.1 to ± 0.2 ft, depending on environmental conditions at the site and 

 distance to the nearest backbone gauge. Such accuracy may be 

 economically achievable with DGPS technology, but this technology must 

 be tested. 



In addition to documented and verifiable surveying procedures, 

 calibration records on the water-level instruments or sensors should be 

 kept. It is recommended that, for Texas inland coastal waters, self- 

 contained pressure gauges with radio transmission capability be 

 investigated for fulfilling requirements of project-specific operational 

 water-level gauges. 



Data stored in or transmitted from the project gauges should be 

 compatible with TCOON standards, for example, as an average taken over 

 a 6-min interval. The data should be incorporated in the TCOON 

 database, together with the associated local reference elevation of the 

 platform and other essential information that will allow re-establishment 

 of the "project station" and access by interested parties. If measurements 

 made to meet project-level requirements have greater tolerances or 

 reliability than backbone gauges, the accuracy range of the values in the 

 database should be provided as part of the information given with the raw 

 or processed data. 



Outside (Gulf-side) Gauges and Wave 

 Measurement 



The capabilities of dredging and navigating in a channel or waterway 

 depend on sea state (surface wave height, period, and direction), as well as 

 on absolute water depth. Measurement of sea state is particularly pertinent 

 in entrance channels and in the offshore of deep-draft channels. Individual 

 surface waves (typical periods of 5 to 10 sec) as well as longer period 

 swell (typical period of 30 to 60 sec) can disrupt or halt dredging 

 operations and make navigation unsafe. Real-time voice reporting and 

 documentation of sea state could be incorporated into dredging operations 

 to make them more efficient, as well as make navigation safer. 



50 Chapter 6 Conclusions and Recommendations 



