Author(s): Giulia Valerio; Stella Volpini; Marco Pilotti

Linked Author(s): Giulia Valerio, Stella Volpini, Marco Pilotti

Keywords: Lake; Internal-waves; Webcam; Currents; Wind

Abstract: Satellite remote sensing has been often used in limnology, providing spatially distributed data that are complementary to the time series of measurements in single lake locations. Maps of surface temperature, chlorophyll, turbidity, bottom cover types and benthic communities are valuable information for the validation of the results of three-dimensional (3D) lake model. Though, these applications are limited by the low temporal resolution of the satellite images, especially in case of phenomena with rapid temporal variations. Since December 2016, a real-time remote monitoring was operated through a webcam positioned 1000 m above the northern surface of Lake Iseo, on a mountain facing the main tributary's mouth. The webcam, which sampled an image twice an hour during the daylight hours, was intended to supplement the temporally sparse images acquired by the satellites. Lake Iseo is characterized by a strong internal wave dynamics in response to wind. In the northern basin, it may happen that the tributary currents determine the formation of areas with different levels of turbidity with respect to the southern waters, providing, over a sufficiently short period of time, a natural tracer for wind-driven currents. The movements of the fronts were captured by the webcam; they were analysed and interpreted on the basis of the overall distribution of solid matter in the lake provided at 10 m spatial resolution by Sentinel-2 and by the wind and water temperature measurements available at the floating station located in the northern basin. The images releveled important spatial patterns of the wind-driven currents in Lake Iseo. These patterns were thus compared with the results of a 3D numerical simulation of the wind-driven currents in the lake. At this purpose we modelled single events, making use of the hydrostatic version of the Hydrodynamic-Aquatic Ecosystem Model (AEM3D), which was already successfully tested in simulating of the internal wave activity in the upper 50 m of lake Iseo. The comparison allowed to widen the evaluation of the performance of the model, based so far on the temperature, oxygen and velocity data measured at single stations only.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022493

Year: 2022