Flood expansion field E-2

The problem

The Lône has reached its 1-in-50 flow four times at Vire-sur-Lône since 2016. Gauge V-07 has recorded the river since 1968, and the large peaks in its record are coming closer together. 1,104 homes sit in the low town, where the river arrives first.

What we built

With the Lône-Vire Water Agency, under agreement LV-2022-114, we turned a former meadow upstream of the town into flood expansion field E-2. A low spillway lets the river in once it passes a set level, and earth bunds hold 418,600 m³ of water until the peak has passed. The field is still grazed for most of the year. It was commissioned in 2022.

During the February 2025 flood, peak flow at gauge V-07 was 301 m³/s, against 412 m³/s for the same event without the field: 27 % less water at the town at the worst moment. Kerrow & Lisle Hydrology verified the figure in its annual review.

Gauge V-07 reports every ten minutes. Our field team cleans and re-levels it on a fixed round, and the readings go to the agency and to the public register at the same time.