How do dams and dikes improve navigation on the upper Danube River?

On the upper Danube River, dams and protecting dikes have been constructed near Passau, Linz, and Ardagger to improve navigation.1

These structures help regulate the river's flow and manage its challenging physical characteristics, such as its rapid current and significant inclination, which can otherwise hinder transport. By impounding water, dams create more stable, navigable conditions, often incorporating locks that allow vessels to pass through different water levels safely and efficiently. Additionally, these engineering works help mitigate the impact of natural obstacles like reefs and shoals that are common in the upper course of the river.1234