Aquaculture Engineering

Practical - 9
Experiment No 1 - Drawing of contour lines by indirect method

Aim
To draw the contour lines for given elevation (Indirect method)

Apparatus
Dumpy level, Levelling staff, Tape, Arrows etc.

Procedure

• The area to be surveyed is divided into number of squares. The size of the square may vary from 5 to 10 m depending upon the nature of the contour and contour interval.
• Set up the level at a convenient place so that all points and bench mark are visible properly.
• Do the “temporary adjustments” properly and make the line of sight exactly horizontal.
• Take the back sight by focusing the telescope towards the staff held on the bench mark and find the height of instrument.
• Held the leveling staff on the corners of the square and find out its elevation.
• The contour lines may then be drawn by interpolation.