PPRI of Lay Aval — Reference Ratings of the Plan for the Prevention of Predictable Natural Risks Flood — Vendée

The reference rating corresponds to the rating of the water body modelled to the right of an existing project or construction plus a safety factor, called “hydraulic revanche” and a value of 20 cm.
Thus “out of water” of a construction will result in a first floor rating greater than or equal to that reference rating as indicated on the regulatory zoning mapping.
It is displayed in NGF-IGN 69 meter, i.e. in meter in the official leveling network in metropolitan France, which is attached to the Marseilles tidegrapher.
These odds are reported perpendicular to the river axis at regular intervals on the regulatory zoning map. At a given location, the reference rating is the value immediately upstream or at the right of the place in question. Between two reference ratings, the applicable rating will be calculated by linear interpolation between the two known ratings shown on the plane.

参考水位（reference rating）指现有项目或构筑物右侧模拟水体的水位值与安全系数之和；该安全系数被命名为“水力复算值（hydraulic revanche）”，取值为20厘米。因此，若构筑物满足“高出水面”的设计要求，则其首层地面标高应大于或等于管制区划图中载明的参考水位。该高程采用NGF-IGN 69米制坐标系，即法国本土官方水准网的米制单位，该水准网依托马赛验潮站（Marseilles tidegrapher）建立。上述参考水位以垂直于河道轴线的方向，在管制区划图上按固定间隔标注。在任意给定位置，参考水位为对应地点上游紧邻处或其右侧的参考水位值。若处于两个已知参考水位之间，则适用水位值将通过该平面图上标注的两个已知水位值进行线性插值（linear interpolation）计算得到。