Fixed system

  The idea of the fixed system is to have continuous measurements. The fixed system consists on a fixed network camera and a PC. The camera has to be installed at a place where it can view a section of the river and a side of it, or a non-moving object that is in contact with the water surface. It does not need to be placed above the open channel; it can be placed on the side, making the installation simpler and cheaper.

  The captured images are then processed with a computer to obtain the streamflow. The streamflow is calculated from the estimated water level, surface velocity and from prior knowledge on the channel geometry. The water level is determined by the separation line of image segments with and without optical flow. Via calibration of the camera position this separation line is mapped to a water level. The surface velocity is calculated using a modified method of the standard Particle Image Velocimetry method. Among the key characteristics of the method is the fact that no tracer particles are needed.