Map Viewing Service (WMS) of the dataset: PPRL of the Lay Basin — Current Reference Ratings of the Plan for the Prevention of Predictable Natural Risks Coastal — Vendée

The reference rating corresponds to the rating of the water body modelled to the right of an existing project or construction. Therefore, the reference rating does not correspond to a water level but to the altimetry of the water body. The height corresponds to the difference between the reference and the altimeter dimensions of the natural terrain参考等级（reference rating）对应于已建工程或建筑右侧的建模水体的特征值。因此，该参考等级并非对应水位，而是对应水体的测高值（altimetry）。该高程差值等于参考等级与自然地形的测高数值之间的差值。