This study site is in the south of the city of Moulins, including the National Nature Reserve of the Val d'Allier which protects 1,450 hectares over approximately 28 km along the lower course of the Allier River. The Allier river is considered as the last wild river of Europe because of its strong fluvial dynamics and remaining free meandering river segments. The studied sector within the nature reserve is still very mobile, with a strong lateral dynamic, where the width of the divagation can be of the order of one kilometer. At this scale, it is unique in Europe.