# StreamflowVL: A Virtual Fieldwork Laboratory that
## 3 Water Discharge Measurement in the Traditional Classroom  
At the University of Basilicata in southern Italy, Applied and Fluvial Hydraulics courses are included in the Civil and Environmental Engineering curricula. Both courses are held in the first year of the Master's degree and typically attract 15-35 students. They are structured to guide learners from the knowledge of basic principles of fluid mechanics to their applications in real-world problems. During the course, different topics are discussed: the dynamics and kinematics of steady and unsteady free surface flows; filtration phenomena in groundwater; laboratory and field experiments on flow fields in open channels; potential and turbulent flows; bed and suspended transport; pollutant diffusion and dispersion; and fluid-structure interaction. The expected learning outcomes are represented by the ability to solve and analyse simple and complex hydraulic problems using analytical, numerical, and graphical models, as well as the technical ability to plan and perform laboratory and in situ experiments. In fact, some problems can be solved in the classroom by applying standard textbook techniques, whereas many of the problems do not lend themselves to such an analysis. Frequently, they require numerical and physical modelling to provide experimental data for design or validation. In addition, model testing requires some experience of experimental techniques, flow measurement equipment, data logging and elaboration. Therefore, the experimental activities are designed to develop these specific skills that cannot be obtained during formal lessons. Applied and Fluvial Hydraulics courses, according to the ECTS, include 54 contact hours, roughly divided into 25-30 h of theoretical lessons, 10-12 h of tutorials, and 14-17 h of experimental work. Assessment is a combination of end-of-semester examinations and practical coursework. The total experimental component is about 45% of the overall assessment, of which the field activities, here discussed, comprise 25% of the subject assessment. In particular, such activities are mainly focused on the measurement and analysis of water discharges in open-channel cross-sections. Such data are an important input for the analytical and numerical resolution of equation systems, in order to analyse complex phenomena such as the fluid-structure interaction [57], the diffusion and dispersion of pollutants in rivers and estuaries [58], the propagation of flood wave along open channels [59], the morphological evolution of rivers [60; 61], as well as the sediment transport in rivers and lakes [62]. The evaluation of water discharge is introduced in the classroom, where the standard measurement methods are explained, as well as the use of simple and advanced equipment [63; 64; 65]. Subsequently, students carry out a sequence of procedures in situ ranging from the selection and demarcation of the cross-section to the acquisition of flow velocities (Figure 1). In the first step, the students select the measurement site, according to specific requirements, and after traversing some reaches of the river. Then, they detect the width, with graduated tape or marked wire, and divide the area into several verticals, where the flow depths are measured with a sounding rod or line. Simultaneously, observation of the velocity are made with classical current meters or sophisticated acoustic sensors at a given number of points on each vertical between the water surface and the channel bed. Once the velocities have been acquired, the students evaluate the water discharge using both analytical and graphical methods in the classroom. During field activities, the students need to know not only how to correctly use the equipment and follow the different measuring steps, but also how to move within the river, which requires a large number of field surveys not always possible due to the variable weather conditions in the autumn and winter months.