What do all the rivers in southern europe have in commen

All the rivers in Southern Europe are connected by the following common factors such as providing water for irrigation, hydroelectricity production and serving as drainage basins. The rivers are mostly used for lazy tourist cruises instead of as active trade routes.

Explanation:

The rivers of Southern Europe have shallow water which makes it safer for tourists to take boat rides. Lack of trade routes leaves the water of the rivers free and thus easily available for hydroelectricity production. Less traffic on the rivers also makes the water consumable and safe for irrigation purposes. The rivers also create a fertile drainage basin as the low lying lands are quite easily accessed by the running rivers.