18 Questions
What is the reference point with respect to which the levels of other points or planes are calculated?
Datum or datum surface
What is the average height of the sea for all stages of the tides?
Mean Sea Level (MSL)
What is the level of a point taken as height above the datum surface?
Reduced Level (RL)
What is a relatively permanent reference point, the elevation of which is known with respect to Mean Sea Level (MSL)?
Benchmarks
What is the highest precision benchmark established by a national agency in India?
GTS Benchmark
Where is the elevation of all GTS benchmarks established with respect to Mean Sea Level (MSL) in India?
Karachi
What is the purpose of establishing benchmarks in levelling?
To determine the difference in elevations of neighbouring points
What is the characteristic of a temporary benchmark?
It is established at the end of the day's work
What is the function of the level tube in a levelling instrument?
To make the line of sight horizontal
What is the purpose of the metal shoe at the bottom of a levelling staff?
To resist wear and tear
What is the GTS benchmark used for?
To establish a permanent benchmark with reference to mean sea level
What does the foot of the metal shoe of a levelling staff represent?
The zero reading
What is the primary purpose of check lines?
To measure the accuracy of main station locations
What type of measurements are taken to locate ground features?
Offset measurements
What is the characteristic of a base line?
It is the longest line
What is the purpose of selecting secondary stations on main lines?
To locate interior details
What are the two methods used for setting perpendicular offsets?
Swinging and using cross staffs
What is the consideration for selecting station points?
It should be visible from at least two or more stations
Test your knowledge of geography concepts, including datum and datum surface, vertical lines, and mean sea level. Learn how to calculate and establish MSL at a particular place. Get ready to navigate the world of geography!
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