Angers, France, acts as a significant bottleneck for the Maine River, exacerbating flood conditions due to a combination of geological and urban development factors. The city is built on a hard, impermeable schist bedrock characteristic of the Massif Armoricain, which restricts the river's ability to spread out and absorb water, unlike the sedimentary soils found upstream where the Sarthe and Loir rivers flow. This geological constraint, coupled with urban development, particularly in the Saint-Serge district which has encroached on floodplains, and the presence of structures like the Verdun Bridge, impedes the river's natural flow. The Verdun Bridge, in particular, was found to have raised the water level by approximately 40 cm during the 1995 floods by slowing down the water's passage. Experts note that the river "no longer breathes" due to these constrictions, and while efforts are underway to mitigate the issue, it is a long-term process.