Velocity sounding – What is WARR?

September 28 2022

WARR stand for Wide Angle Reflection and Refraction, a technique to measure the GPR velocity in the ground or in other materials.

Velocity sounding is a useful way to estimate the velocity of the signal in the subsurface. The two most common methods for velocity sounding are Common Mid-Point (CMP) and Wide Angle Reflection and Refraction (WARR). Note that both these methods require separate transmitter and receiver antennas.

WARR can be carried out in an area with a horizontal layer reflector. The receiver antenna is placed in a mid-point, while the transmitter antenna is moved from one side to the other, continuously, or stepwise.

In contrast to CMP measurements and since the point of reflection will vary, WARR is assuming sub-surface layers to be horizontal. Deviation from this assumption will cause an error in the velocity estimation. WARR measurements are however, easier to perform than CMP measurements.

In the resulting radargram, the slope of the reflected wave is used to calculate the mean velocity of the area you have investigated:

Velocity sounding – What is WARR?

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