Yes, Ultrasonic level transmitters can also be used for Open channel flow measurement.

Ultrasonic measurement provides a non-contacting technology for distance measurement which can be configured to provide accurate continuous measurement of product depth / height. Ultrasonic measurement provides maintenance free height or depth measurement of solids, chemicals and water, from food ingredients to corrosive chemicals, waste water and sewage. As this technique makes no contact with the material, there is no on-going cleaning, wear or maintenance schedule.