ABSTRACT
Nearshore hydro- and morphodynamic data were collected during a field experiment under calm conditions, moderate conditions, and storm conditions with dune erosion in the collision regime. The experiment was conducted on the Sand Engine near Kijkduin, the Netherlands, from October 18, 2021, to January 7, 2022. Two artificial unvegetated dunes were constructed just above the high water line to measure storm erosion and dune impacts from higher water levels and waves. During the experiment, three storms occurred that resulted in significant erosion of both dunes. The collected hydrodynamic data include pressure sensor and velocimeter data along two cross-shore transects. The collected morphodynamic data include bathymetry and topography surveys, optical backscatter sensor data in the inner surf zone, and a continuous cross-shore line-scanning lidar data set of the dune face. This comprehensive data set can be used to (1) study relevant nearshore hydrodynamic and morphodynamic processes that occur during calm conditions, moderate conditions, and storm conditions with dune erosion in the collision regime, and (2) validate existing dune erosion models.
ABSTRACT
High quality laboratory measurements of nearshore waves and morphology change at, or near prototype-scale are essential to support new understanding of coastal processes and enable the development and validation of predictive models. The DynaRev experiment was completed at the GWK large wave flume over 8 weeks during 2017 to investigate the response of a sandy beach to water level rise and varying wave conditions with and without a dynamic cobble berm revetment, as well as the resilience of the revetment itself. A large array of instrumentation was used throughout the experiment to capture: (1) wave transformation from intermediate water depths to the runup limit at high spatio-temporal resolution, (2) beach profile change including wave-by-wave changes in the swash zone, (3) detailed hydro and morphodynamic measurements around a developing and a translating sandbar.
ABSTRACT
PURPOSE: One of the singularities of the eyes of snakes is the presence of the spectacle, a transparent and vascularized integument covering the cornea. The spectacle is completely renewed during ecdysis. Combined scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT), and conventional macrophotography were used to image this phenomenon. MATERIAL AND METHODS: A spectral OCT/SLO examination and macrophotography were performed in four healthy adult corn snakes (Pantherophis guttatus) and one healthy adult California king snake (Lampropeltis getulus californiae) the day before the start of ecdysis and then daily during ecdysis. RESULTS: In all animals, ecdysis lasted 5 days. The spectacle was hardly visible at baseline, but became obvious at day one, while the subspectacular space became larger and the superficial cornea presented a hyperechoic band. At day two, eye surface became translucent, and at the same time, vascularization of the spectacle was visible using SLO. At day 3, the vascularization was no longer visible, while the subspectacular space increased and the eye surface remained translucent. At day 4, the eye surface was transparent and the superficial hyperechoic band started to become less bright. At day 5, the old spectacle was shed and all the parameters returned to baseline. CONCLUSION: We hypothesize that the echogenicity modifications of the anterior cornea correspond to major metabolic activity associated with new spectacle formation. This increased metabolic activity may contribute to the neovascularization and play an important role in the accumulation of fluid in the subspectacular space, facilitating the shedding of the old spectacle.
