Which of the following type of leveling is also known as fly leveling? 

Explanation:

Levelling is defined as the branch of surveying essentially used to determine the relative heights of the different points on, above or below the surface of earth.

Objectives of levelling

• To determine the elevation of the given points with respect to the given reference line or datum.
• To establish the points at a provided elevation or at various elevations with respect to a given or assumed datum.

Types of levelling

(i) Cross section levelling

• It involves the process of taking the levels on each side on the main baseline at right angles to that baseline so as to determine the vertical cross-section of the surface of the ground or the underlying layer or even both.

(ii) Profile levelling

• It is the type of direct levelling that is used to determine the elevation of the points at measured intervals along a line so as to obtain a profile of the surface along the line.

(iii) Precise levelling

• It is used for establishing a benchmark with high precisions at widely distant points, it is conducted by some govt. an agency such as the great trigonometrical surveying of India department for establishing the G.S.T benchmark.

(iv) Differential levelling

• It is carried out with the object of determining the difference in the elevation of the between two points irrespective of the horizontal position and with respect to each other. It is commonly known as fly levelling.

(v) Reciprocal levelling

• It is used to determine the difference in the elevation between the two points is determined by two sets of reciprocal observations when the points are separated by large intervening distances like lakes, depression.