Name ______________________


SO432, Hydrography

Exam 2

Fall 2000




5 @  4 points



Short Answer

5 @ 10 points




1 @ 30 points 









For the definitions and short answers, insure that you use proper terminology and show that you understand the concepts and principles involved.


Insure that you devote sufficient time on the essay. You should do a good job of synthesizing what we have covered.




Definitions. Define 5 of the following 6 terms:






        NAVD 88:




Short Answer. Answer all 5 of the short answer questions.


1. There are many similarities between the digital map products from USGS and NIMA. Discuss the biggest difference, and how it affects the user who wants to display the data on screen with a conformal, equal area map projection.



2. The tidal record above covers four days at Annapolis.  Use the diagram to explain the following:

        What value of sea level is used on charts, and how is it defined?

        What readings from this record would contribute to that determination? Clearly label those values.

        How long would the readings be taken to determine this value of sea level, and why is this period important?

        Would sea level on the chart correspond to sea level on the land?


3. Discuss the tradeoffs in scanning a map to produce a DRG. What is the optimal solution?


4. Why is radar altimetry attractive for mapping the deep oceans, despite its limitations?



5. Imagery.

a)      Why is imagery used in mapping or charting?

b)      Discuss how you would use four of the imagery interpretation keys in looking at a scene along the coast?


Essay. Discuss how surveying for hydrographic charts is done. Insure you cover:

        The US agencies responsible for the work.

        How the survey effort is prioritized.

        The survey tools and operations, including design of the survey.

        How this process has changed over the past century.

        What we must still worry about obsolete methods.