A system for observing a flow characteristic of a fluid is provided. The system comprises at least one radar sensor that is a Multiple-Input Multiple Output phase radar sensor configured to create a virtual array. The system also comprises processing circuitry. The radar sensor(s) are provided at a distance above the fluid. The processing circuitry is configured to receive sensor data from the radar sensor(s). The sensor data includes at least one of a fluid speed or a fluid surface level. The processing circuitry is configured to determine the flow characteristic based upon the sensor data.