There are several highly sophisticated technologies available for measuring streamflow. However, no amount of electronic wizardry will guarantee that you come home with a good discharge measurement. There are many things that can wrong such as with the electrical power or electronic communication between the system components. In the event as an electronic failure you are screwed because these devices are so expensive that no one can afford to carry a spare.
Water monitoring is a place-based activity. The work is wherever the water is, which is all over the planet. A stream hydrographer can cover a very large geographic area so regional offices typically only concentrate a small number of hydrographers at any one location and there are many locations. Water monitoring agencies have limited resources available to develop specialized training material or to send hydrographers on specialized courses so the most prevalent mode of career development is on-the-job training.