Water level

Definition

The water level W is the vertical distance of a point of the water surface above or below a reference level defined, e.g., by the deepest point of the cross-sectional profile, sea level or gauge zero (GZ).

Figure 1 Water level W and gauge zero GZ

Principle of measurement

The water level sensor is installed above a river or channel and transmits a short radar signal towards the water surface. As illustrated in Figure 2 this signal is reflected at the water surface and recorded by the sensor now working as a receiver. The traveling time of the impulse is directly proportional to the distance between the sensor and the water surface.

Figure 2 Principle of water level sensor