A survey of the water flow, bottom morphology and depth of the canals of Padova, Italy, and a comparison with historical data

This work aims at assessing the flow rate, bottom depth, and depth of the canals concentrating on the historical urban area of Padova. In addition, it takes place in the framework of a a project which aims to take care of the city channels, ‘Padova e i suoi canali’, co-financed by the Municipality of Padua and the CARIPARO Foundation and started in June 2021, with a partnership between the Municipality of Padua (leader), the Piovego social cooperative, the Amissi del Piovego NGO and the University of Padua - Department of Industrial Engineering (through LASA - Laboratorio di Analisi dei Sistemi Ambientali ). Padovans are increasingly separated from their river by flooding in cities and neighboring territories, which is seen as a threat to safety, economic activity, and their homes. Fundamentally , recognizing the shape of canals and their interrelationship processes, a knowledge of how canals hydraulic and ecological functioning change in present versus past environments, and especially in relation to the effects of human activity, is needed. Although these changes can be caused by climate change and human activity controls during the years of the functioning of the channels, their knowledge can help developing appropriate novel management schemes for urban canals. To accomplish these goals, canal depth and flow rate, the most essential aspects which need to be considered for successful management schemes, have been measured utilizing an Acoustic Doppler Profiler (ADCP) instrument to record data of water speedand bottom depth. By utilizing this instrument, we were able to measure river discharge, 3-Dimensional water currents, depths, and bathymetry from a moving or stationary vessel. The data has been exported to MATLAB software so that the depth variation along the canals can be visualized. The Velocity Mapping Toolbox (VMT), a MATLAB-based software, was used to further process and visualize the collected data along transects in Canals. We were able to process, visualize, and analyze ADCP datasets by using this software; we also used it to export ADCP data into QGIS compatible formats. With the intention of acquiring comprehensive information about the bottom depth and depth of the canals, two different types of trips have been conducted with the ADCP instrument. One of the trips traveled along the edges of the canals and another was a zigzag trip to acquire a complete picture of the bottom shape. In these cases, the water speed was not precisely measured due to the perturbation caused by the movement of the boat. Consequently, for the purpose of determining the water speed as well as making a comparison between the bottom depth of the current situation and a historical study, forty seven sections, starting at the Ponte del Sostegno and going to the Arches Gate have been allocated for the recording of data. In conclusion, the bottom characterization (maximum depth varies from 1.27m to 2.35m in the main canal in Tronco Maestro, and 1.56m to 1.67m in the secondary San Michele canal; Mean depth varies from 0.22m to 1.11m in the main canal in Tronco Maestro, and 0.55m to 0.72m in the secondary canal) show a shallow canal in Tronco Maestro, providing the primary information to implement future management approaches to improve water quality in the canals while safe guarding biodiversity and taking care of flood risk, which is the only current management priority.