Upriver Propagation of Tidal Waves and Mouth Bar Influence at a Microtidal Estuary: Observations and Modeling

The estuary of the Misa River, located in Senigallia (central Italy), is a micro-tidal environment typical of the Adriatic basin. The present work focuses on the numerical modeling of the tidal action along the final stretch of the river, also in relation to the role of local river bedforms, and builds on field data obtained from: two hydrometers recording the river stage, an acoustic sensor H-ADCP collecting river stage and discharge during flood conditions, a tide gauge measuring the water-surface level in the sea, a suite of instrumentation deployed during a field campaign in 2014. The river topography and bathymetry are modeled using a digital terrain model, surveys of the estuarine area, surveys of specific cross-sections in the river. After the model calibration, which provides the optimal choice of the riverbed roughness, the work analyzes the role of the tide forcing, which propagates upstream for almost 2 km. The effects on the hydrodynamics induced by bedforms located at the estuary are also investigated. Specifically, a partially emerged bar, generated in the recent years upstream of the river mouth, intermittently shows up and moves within the estuary. Such bedform significantly affects the local dynamics and produces relevant changes in the final reach of the river, reaching distances of more than 1 km from the mouth.