Simple download service (Atom) of the dataset: DDT 70- Isocotes of PPRI n°20090015 Durgeon Amont Outside Durgeon Aval

The isocotes of the PPRI are the altimeter values (Z in the NGF 69 marker) of the flood heights calculated for the reference flood. Subject to the rules for constructions and the recommendations to be observed, laid down in the regulation of the PPRI, isocotes make it possible to calculate the altimetry of the highest waters which should be observed for the installation of an authorised construction. This height is calculated as follows: Z = (a * z2 + b * Z1)/(a+b) with Z1 = nearest isocot of highest value, Z2 = closest isocot of the lowest value, a = distance between the Z point and the Z1 isocot measured perpendicular to the isocot route, B = distance between the Z-point and Z2 isocot, measured perpendicular to the isocot route. A schematic generally makes this formula explicit in the appendix to the PPRI presentation note.PPRI的等洪水位线（isocotes）为基准洪水计算所得的洪水高程数值，对应NGF 69（National Geodetic Framework 1969）坐标系下的Z值。遵循PPRI规程中规定的施工规则与应恪守的技术建议，等洪水位线可用于计算经许可的建筑安装时所需监测的最高洪水的高程。该高程的计算公式如下： Z = (a * Z2 + b * Z1)/(a+b) 其中，Z1为数值最高的邻近等洪水位线，Z2为数值最低的邻近等洪水位线，a为测点Z与Z1等洪水位线之间垂直于等洪水位线走向的距离，b为测点Z与Z2等洪水位线之间垂直于等洪水位线走向的距离。 PPRI说明手册的附录中通常配有示意图以直观阐释该公式。