AZI of the catchment area of the lake of Grandlieu — flood areas — in the Loire-Atlantique and Vendée

These data represent the different beds of the water courses mapped according to the hydrogeomorphological approach (010: the minor bed corresponds to the main channel, 020: the average bed is flooded by frequent floods, 030: the major bed is flooded by great floods, 040: the exceptional major bed is flooded by rare floods). The study concerns the watershed of rivers belonging to the catchment area of Lake Grandlieu. It consists of the rivers of the Acheneau, Boulogne, Tenu, Issoire, Logne and Ognon and extends over the two departments of Loire-Atlantique and Vendée. __Origin__ This atlas of flood zones (AZI) was carried out using the hydrogeomorphological method conforming to the guide &Atlas of flood zones by hydrogeomorphological analysis — CCTP reference terms for the realisation of atlases — March 2002 & the Pollution and Risk Prevention Directorate of the Ministry of Ecology and Sustainable Development;. This method s' relies on 2 complementary tools: L' stereoscopic analysis of aerial photographs and field observations. The envelopes of flood zones defined in this way have been reinforced by a search for historical floods. The inundability maps were made on the background of the scan plan 25 of l'IGN to the #x27; scale from 1/25 000 with zooms to 1/10 000 on the areas at stake. L'atlas consists of 24 boards at 1/25 000 covering all the courses of water concerned and 7 boards at 1/10 000 covering the areas at stake. The report and mapping are available on the websites of the services of the State in Loire-Atlantique. __Partner organisations__ DDTM Loire-Atlantique [See this page on geo.data.gouv.fr](https://geo.data.gouv.fr/fr/datasets/e6cc7673fac047e2759490a3659040ad0a756f07)