Laboratory experiments of rip current systems are performed in a wave basin with a bar and rip channel geometry at the Ocean Engineering Laboratory at the University of Delaware. The experiments include both in situ water level and velocity measurements and optical visualization of the flow field under a variety of normal-incident wave conditions. Digital video is used to record surface drifters moving through a rip current system. A method is presented that tracks these digitally-recorded drifters into long Lagrangian sequences. The laboratory measurements capture both an Eulerian and Lagrangian description of the rip current system. Time-averaged rip current properties are calculated and analyzed using both in situ and video measurements. From the video, Lagrangian velocities are computed with forward differencing of the low-pass filtered drifter tracks. Wave properties are also estimated using the orbital drifter motions and linear (Airy) wave theory. The effects of various wave conditions on the time-averaged rip current systems are investigated to show that wave height is a critical parameter. Measurements of circulation cells are obtained by spatially averaging the drifter track velocity measurements into a polar grid ranging from 0.25 m to 3.25 m from the center of the cell. Circulation cell features, such as the center of circulation and cell width, are calculated to characterize their response to various wave conditions. Spectral analyses are used to characterize the rip current pulsations in the experimental measurements. Three frequencies are found to be energetic in several of the experiments in the low frequency band: the wave group frequency, a lower frequency, and the interaction of the wave group and lower frequencies. Some experiments have significant energy at each of the three peaks, where others have only one or none. The lower frequency motions have also been found in the video measurements and attributed to rip meandering. Possible causes for the low-frequency pulsations, including wave basin seiching, circulation cell instabilities, and wave-current interaction, are discussed. This thesis adds to previous rip current studies by providing a spatially-large and time-varying perspective of rip current systems as a whole.

In this master's thesis, a numerical model of groundwater flow in a contaminated area of Hradec Králové was created. After that, a circulation well was introduced. Two circulation well variants, which differ in the amount of pumped water, were examined. All simulations were performed with the aid of a finite element solver Feflow 5.2. The values of hydraulic head resulting from the mathematical model are in a good agreement with those obtained from the field measurement. The groundwater flow present in the area of interest exhibits south to southwest direction. After introducing the circulation well, I focused on the influence of the amount of pumped water on the groundwater flow. The outcome of this observation was that during the higher volume pumping, the circulation cell is larger and therefore has a higher influence on the groundwater flow. I evaluated that it is more efficient to pump a higher amount of water in the investigated area.